Recommendations to Management Essay

Problem: Increase marketing of Chiropractic Services. My aim is to bring strategies that will increase the profitability of your practice, while at the same time improving patient satisfaction and results. In the process of achieving these aims, I also seek to improve the public’s image of chiropractic care. First Recommendation: To increase profits and public awareness. Rational: Increasing profit is the main goal in any business. To help you increase profits I wish to provide advice in the following areas, as suitable: †¢ debt reduction †¢ retirement planning †¢ overhead reduction †¢ investment strategies †¢ bankruptcy guidance †¢ collection assistance I feel that by using sound business advice in these areas you will improve your profits marginally. Together we will evaluate what products or services are making you money. We will decide whether other products or services should be promoted in addition or in place of current services. To cite a classic business planning question, â€Å"Are you making 80 percent of your profits from 20 percent of your offerings?† Are you wasting time on products and services that don’t return the favor by providing you with profits? Again, together we will find these answers. Why is this recommendation important now? I feel will that with the current economic situation, now is the time to work at increases your profits to its fullest. Now is not the time to let your business take a down fall. Priority ranking of the recommendation: The priority for profits is an important need in business. Proposal: I propose that within the next few years your Chiropractic office will increase profits by increasing services and lowering costs. This will be  achieved by first looking at business expenses. One seriously important area to examine is staffing. This is typically one of a company’s biggest expenses. You need to ask yourself â€Å"Did you make necessary cuts during the recession or are you still overstaffed? Are you getting your dollars’ worth from every employee?† Make necessary adjustments now. Next, we need to examine your other expenses as well. These expenses include expense accounts to seminars, up to magazine subscriptions. We will go over your entire profit and loss statements for this year. Remember to track everything. Scrutinize your cash flow, profits and trends every week. What’s more, figure out what your company’s important numbers are. Second Recommendation: Increase marketing and public awareness. Rational: I do not recommend door-to-door surveys or other unsuccessful marketing gimmicks. Nor do I support high patient fees or unwarranted patient visits. Instead, I want to custom-tailor solutions to your distinctive needs and goals. Some marketing tools that I recommend you use are questionnaires, patient fact sheets and health concerns hand outs. These items can be posted in your office, made into brochures, newsletters, newspaper articles, and reading material in specific areas of your office like reception area. Why is this recommendation important now? In order to make money and have a profit you must advertise. This advertising will increase the public awareness of your business and the services you offer. Priority ranking of the recommendation: I feel that this is one of the most important recommendations. Good marketing is the key to great business and success. Proposal: I propose that you step up your marketing by using public relations, Web marketing, email newsletters, and other targeted or large outreach. This will be a great way to market your business since you are a small company. How do these recommendations align with the mission statement and vision? Mission Statement: Rantoul Chiropractic Clinic is committed to finding the cause of your symptoms and treating it in the most effective manner possible. We are also committed to explaining your condition to you in a manner in which you will know and understand what the problem is and what it  will take to correct it and to keep it from reoccurring. Vision Statement: Our Vision is to embrace our community and strive together for optimal health through the journey of life. Promoting Excellence and Assuring Quality in Chiropractic Education. We understand the chiropractic profession and appreciate the services, workflow, and barriers that frustrate you and slow you down. References RJF Consulting. http://www.chiroevidence.com/RJFConsulting/mission-values.html

Human body Essay

A trip to the cinemas or even to the local bookstore will reveal the present generation’s fascination with the folkloric undead. This fascination, however, is not a new one as most of the present â€Å"lovable† undead characters are actually just old characters that have been given a make-over. From the charismatic vampires of Anne Rice in her Vampire Chronicles series to the morbid and gruesome zombies in the films, the folkloric undead have taken on a new shape from the early 19th century. Perhaps, the change can be attributed to a more imaginative set of authors and writers but then again much of this change can also be attributed to the developments in science and medicine which have allowed for a deeper understanding of the human body and the undead who feast on them. The vampires that Anne Rice creates are more seemingly human than they are vampire. This personification allows the reader to identify with the characters. As Anne Rice carefully describes every sinew and vein that runs down the potential victim’s neck, the reader feels as if he or she were the one taking that fatal bite. Dracula and Frankenstein have also been given more human sides as we see in the movies. The tale of love and revenge has no application to things which are not human. This is something that these writers and directors have realized. In order to capture the attention of the audience, one must be able to personify these characters and give them feelings and even appearances that can be mistaken for human beings. While arguably Frankenstein may be far from being human in the sense of the word, his feelings of revenge and even loyalty at times is too human to be mistaken for anything else. By employing the literary device such as personification and developing an understanding of the human body, today’s writers have evolved the genre from the simplistic undead of the earlier century.

Marysville General Hospital

As the CFO of Marysville General Hospital, I realize we have a serious accounts receivable problem here. It has gotten out of control, and we are going to get it back in control. All it takes is a little effort from everyone to get us back on here. With the process improvement plan I am proposing, I will need the assistance and cooperation of the medical staff, the clinical departments, the business office, health information management, and all other departments.To propose my plan of improving the current situation of the hospital, I will need to get a current report on all past, current and future collection data from the finance department to determine how much we are actually losing at this point. I need to collect the admissions and registration information from the business office. I also need electronic medical records information from health information management. I need a current report on charge captures from the nursing staff.I need a current report on the status of claim s processing, payment posting, and secondary billing/patient follow-up. For this plan to be a success we will need complete cooperation from everyone. We need to get some experienced personnel or train our current personnel to do the admissions more accurately. The nursing staff should not have to check vitals and register patients also. Patient registration should be done before the patient even sees the nurse unless it’s a life or death situation.Clear instructions will be given to these staff members to ensure that we have all the current contact and billing information and legible copies of all documents and claims are processed appropriately. With verification of all information, we should see a more smooth billing process and the correct plan codes being applied to the various accounts. The implementation of the electronic medical records has been very helpful to all departments because all patient information is in the system and accessible if needed.However, we have t o ensure that our physicians are charting their patient’s information in a timely manner and giving detailed information about diagnosis and plan of care. If the physicians are not completing their charts on time, we will have to put them on some type of suspension until they are up to date on their charts. We cannot let them continuously see patients and not complete their charts because they would have too many to try to catch with. Therefore, we should have time period deadline for all patients’ charts. If the physicians are not being  compliant, they will go into suspension.We understand they have a busy schedule, but if we have to constantly remind them that there are charts that need to be completed, we will do that. We will designate a couple of staff members to stay on top of the physicians if we deem it necessary. To help with charge captures, we will invest in the â€Å"Clean Claims Module† from MedXL to ensure that all the claims requirements for th e various insurance companies are current and up-to-date. It will also ensure that we are notified of any changes that may occur.I would much prefer if we invest in this program to ensure clean claims processing to ensure we receive payments for services provided in a timely manner. Every little bit helps. As far as self—pay patients, we should look into some type of discount plan that may assist these patients with the cost of their services. If we can offer some kind of discount or financial assistance to our patients, it may prevent us from having to send so many of their accounts to the collection agencies where we are losing monies because of the fee the collection agencies charge to collect on our behalf.We can also remind patients about their bills when they come in. There should be a notification that pops up when we go into a patients account that lets us know they have an outstanding balance. With the cooperation of all departments and staff members, we can bring Ma rysville General Hospital back to previous accounts receivables standings. Teamwork is required and not optional. Let’s keep our community happy.

My research paper needs to be on how the government addressed past

My needs to be on how the government addressed past economic downturns and recoveries, what caused them and wha - Research Paper Example The government has been responsible to respond to the poor health of the economy, struggling to find a way in which to regain ground so that the millions of those suffering economically could recover. The many avenues towards economic health that the government has taken have been wide and varied, depending on the policies and the platform of those who were in office. The first true crises of the 20th century occurred in 1929 as the collapse of an ill-conceived stock market plan led to the collapse of industry within the United States. The 1930’s was a time filled with the doom of her citizens, the hard economic times creating a void that left many without jobs, without hope, and without enough to sustain their families. The 1940’s saw an economic challenge of a different kind as World War II took a great deal of resources that meant that citizens had to make significant sacrifices. However, the war led into the 1950’s, a time in which the innovations from the te chnologies that were created from the wartime efforts provided for a surge in commerce, the beginning of a global economy providing for high levels of income for Americans. The 1970’s saw the United States in a state of a recession with many losing their jobs and a notable shift in the way in which employment was viewed became a part of the sociological landscape. Black Thursday On the day that would come to be called Black Thursday, October 24, 1929, the stock market fell 34 points, which represented a 9% drop for the day. The extremity of the day was caused by a selling panic, driving the prices down and losing billions for investors. The simple answer about how it was caused was because of the speculator boom, but the causes were far more complex than the traditional answer to this question. The market was in a highly sensitive state by that fateful day, some of which was due to the real estate decline starting in 1925, some due to simply because the fear of a crash caused a run that caused a crash. The market had come to a high plateau and the fear of the end had caused the inevitable end. The rising stock prices were less due to value than to speculation manipulations. As an example, RCA was worth $1.32 in 1925, $6.15 in 1927, and $15.98 in 1928 before the stock split (Bierman, 1998, p. 9). The 1920’s represented a rise in technological advancements that affected the nature of American life. The automobile industry evolved during this period and the innovations of the Ford company in assembly line management and the level of wage paid to the workers created a working atmosphere in which the middle class was being born. Money was flowing and people were experiencing a new level of comfort that had never before been experienced. However, when the crash took all of that away, the resulting depression plummeted that emerging middle class into a poverty that was unprecedented on American soil. Farmers experienced losses that could never have been predicted, food prices at all time lows. Market Prices as they Plummet (Crewe & Ingram, 2005, p. 20) Homelessness was rife and ’Hooverville’s popped up all over consisting of huts in urban landscapes without electricity, water, or sanitation, named after President Hoover as ultimately,

Amadeus Essay Example | Topics and Well Written Essays - 500 words

Amadeus - Essay Example e classical composer Mozart, director Milos Forman took the 1979 libretto of the musical play by Schaffer and turned it into a modern classic of high admiration among high brow film aficionados. The music of the film, being based on the original works of Mozart leaves the viewers glued to their seats at the film unfolds in relation to the chosen musical pieces. It was this music that gripped my interest when I first sat down to watch the film for our class. I cannot fault the film for its musical brilliance and its painstaking attention to the small details that went into the production of this movie. However, there were a few things about the production itself that struck me as odd. Simply because I found it hard to swallow a crossover of influences between the historical world of Mozart and the modern era of the 1980s. To begin with, I never expected to hear modern English slang being spoken in a film such as Amadeus. I had thought that the original play creator and then the Hollywood film maker would have done their best to stay true to the language of the era being portrayed. A necessary point, in my opinion, that adds to the authentic feel of the movie experience. The gyrating laughter of Tom Hulce also got on my nerves later on. I understand from the narration that the reason the laughter sounded that way was because it was meant to offend Salieri who felt that God mocked his talents by bestowing an immense talent in the spoiled brat name Mozart. This is also another point that left me wishing that the film makers had taken greater care in their portrayal of Mozart in the film. The heavily fictionalized account of the life and times of Mozart has become the basis by which most of todays students first get to know about the prolific composer. However, because the film does not present an accurate account of his life and the people of notable influence upon him, Mozart is instead seen as a madman who was always in need of money and uncaring for both his

Sale Of Goods Coursework Example | Topics and Well Written Essays - 4500 words

Sale Of Goods - Coursework Example He also found that the books in another container were about gardening instead of politics. The books in the third container conformed to the terms of the contract of sale. There are some statutes that favor David in respect of the books that were about gardening. S 13(1) of Sale of Goods Act 1979 states that, â€Å"Where there is a contract for the sale of goods by description, there is an implied condition that the goods will correspond with the description.†1 According to the given facts, David made a contract for goods that fit a particular description i.e. the books entitled How to win votes. There was an implied condition that the books must have been the same. Books about gardening were unrelated to the terms of the contract. ... He also has a right to reject the books because there has been a breach of condition. The contract between David and Obama is a non-severable contract. This means that S 11(4) is applicable which states that, â€Å"Where a contract of sale is not severable and the buyer has accepted the goods or part of them, the breach of a condition to be fulfilled by the seller can only be treated as a breach of warranty, and not as a ground for rejecting the goods and treating the contract as repudiated, unless there is an express or implied term of the contract to that effect.†3 One of the containers had the books that were in perfect condition and were in conformity with the contract. David cannot reject those books. However, when he rejects a part of books, he would have to treat the breach of condition as a breach of warranty and would not be able to treat the contract as repudiated. He would be entitled to claim damages from Obama for the loss that he has sustained due to the delivery of wrong books. Obama’s view that David can easily on-sell the books based on gardening is of no consequence because the delivery of those books was not a part of the contract. Their contract was made through emails. This means that a written record of their conversations can be obtained easily. David discovered that the entire contents of one container were badly damaged. Obama is denying any responsibility for that and the Jardine Carriers, with whom Obama had contracted for the carriage of the books, say that it has â€Å"nothing to do with them† because there was no contract between JC and David. The contract between Obama and David was made on CIF terms. CIF (Cost, Insurance and Freight) means that the seller delivers when the goods

Short paper Essay Example | Topics and Well Written Essays - 500 words

Short paper - Essay Example It can be said beyond doubt that academic education plays an important role in sharpening and broadening the minds of the students, however practical application of the theoretical studies do much more. Providing vocational education in the high schools also diversify the curriculum, providing students with greater learning and experience. If a person wishes to pursue a career in a technical field, he needs to have a solid foundation and practice to ensure a successful career. This foundation can be made if high schools offer optional vocational education to its students. Vocational education also prepares the students for their practical life by granting them exposure to the practical work. If the students get vocational education during their high school, they can also polish their skills by working part time in the related field; so that by the time, their high school is finished, they would be ready to follow their respective careers. Providing vocational education in high school also allows the students to recognize their interests so that, in future they can opt for a career that suits their liking. The market for skilled technical labor is constantly on the rise. Technical workers are hugely in demand and thus get high compensations for their work. For the country to fulfill its technical needs, it requires a greater supply of such labor. Not everyone plans on attending further education in university or college.

Business Impact Analysis Essay Example | Topics and Well Written Essays - 1000 words

Business Impact Analysis - Essay Example ing the postal system is the Office of Inspector General (OIG) whose chief officer reports directly to the Postal Office’s Governors and not subject to any supervisory jurisdiction to any other Postal Service in the country (USPS OIG: David Williams, 2010). Due to the delicate nature of the tasks, responsibilities, and accountabilities accorded all personnel working for USPS OIG, a business impact analysis is most useful in assisting management in determining which functions are critical to the continued operation of the organization. According the its official website, the mission of the office is to assist in the maintenance of confidence through safeguarding the organization’s bottom line concurrent with undertaking both audits and investigations. It was specifically stated that â€Å"audits of postal programs and operations help to determine whether the programs and operations are efficient and cost-effective. Investigations help prevent and detect fraud, waste, and misconduct and have a deterrent effect on postal crimes† (USPS OIG: Mission, 2010, par.1). In this regard, the OIG is tasked with focusing on the following strategic goals which are considered relevant as giving direction to the organization: generation of revenue, improving and increasing the organization’s efficiency in performance, focusing on improvement of service, emphasis on a culture which focuses on the customers, increasing awareness on sustainability efforts, and regular monitoring and apprising on regulatory studies and obligations to report (OIG: Semi-Annual Report to Congress, 2008, 7). Business impact assessment is one of the steps incorporated in business continuity planning. Since OIG undertakes audits and investigations, the initial step to identify critical areas that would ensure the accomplishment of identified objectives entails reviewing the STEEP (social, technological, economic, ecological, and political) factors that impact its operations (Van der Heijden, et.al.,

Ensuring Employees Pay for Extra Cost of Healthcare Essay

Ensuring Employees Pay for Extra Cost of Healthcare - Essay Example Employers should devise an economic program that would ensure employees compensate the extra cost over premiums spent on lifestyle-related diseases. The following is a proposed framework that employers would use to ensure employees pay for extra costs above the coverage premium spent on lifestyle-related conditions. First, employers should schedule all chronic conditions that are lifestyle-related and contribute to the increase in the cost of the premium. A possible list should include conditions such as diabetes, some forms of cancers, heart disease, and obesity-related illnesses. In order to ensure a robust program, accredited health care professionals should approve the scheduled list of complications and ascertain they are lifestyle-related. The second process in the framework should involve calculations of direct and indirect costs incurred from health-related illnesses. The direct cost calculation is simple and can be estimated based on extra expenditure the company has on inpatient and outpatient services. They include extra expenditure on services including surgeries, radiological processes, laboratory tests, and drug therapies. Indirect costs include an estimation of resources forgone by the firm or company because of a lifestyle-related health condition that affects an employee. The value of lost work because of absenteeism should be calculated based on accumulated wages throughout the period. Other forms of indirect cost include the value of increased insurance incurred by the company because of lifestyle-related conditions.  Ã‚  

Pros and cons to open a small business Essay Example | Topics and Well Written Essays - 1000 words

Pros and cons to open a small business - Essay Example This discussion illuminates the many advantages and disadvantages of opening a small business then briefly discusses the merits involved in the purchase of an existing business as opposed to starting one from the ground up. For a person that embodies the true entrepreneurial spirit, the chief goal and appeal of opening a small business is to create something novel, not simply in managing someone else’s conception. Because of this, beginning a business of one’s own construct is an appealing notion (Helfand, 2007). Operating one’s own business can be advantageous in many ways. First, and probably foremost is that a person can be their own boss. They are therefore able to make their own decisions and set their own hours. Nobody admonishes the owner for being late or taking an extra day’s vacation. No one tells the boss where to be and when to be there. The owner of a small business answers to no one besides the customer and even this is a choice. Unreasonable clients can be fired. The owner is not involved in petty organizational politics. No one is trying to undermine your authority or accomplishments so as to ‘climb the corporate ladder’ quicker. The owner of a s mall business is and always will be at the top. There is no ceiling on earnings potential to the owner of a small business. It is the best way to realize the ‘American dream.’ The more the business succeeds, the more profit is made and the owner decides how to distribute the earnings. Gone are the days of working for a pre-determined salary knowing that efforts made were probably making money for invisible investors who didn’t have a clue about the business nor appreciated the tremendous sacrifices that allowed it to profit. The owner of a small business has the ability to develop particular skills and knowledge needed for the growth of that business instead of having to focus on only the constrained

Pollution and Encoachment of Coastal habitats in California Essay

Pollution and Encoachment of Coastal habitats in California - Essay Example Policies have been implemented that allow for greater leniency in the granting of permissions for off-shore oil drilling, and with a reduction of personnel in organizations such as the Environmental Protection Agency, the strict guidelines that have survived are not being sufficiently enforced. The increasing number of people inhabiting areas near water sources such as rivers, lakes, streams and wetlands has caused greater pollution due to more runoff, which ultimately contributes to the pollution of harbors and bays. Polluted runoff and the occasional oil spill threaten coastal resources and often cause beach closures, resulting in risks to public health and significant impacts to local economies. With the advent of the deterioration of California’s coastal environment, some specific programs and organizations were created, such as the Critical Coastal Areas program, which delineates specific land areas of the California coast â€Å"where state, federal and local government agencies and other stakeholders have agreed to improve degraded water quality or protect exceptional coastal water quality from the threat of pollution† (CCA Draft Strategic Plan 1), and the California Coastal Commission, established in order to â€Å"protect, conserve, restore, and enhance environmental and human-based resources of the California coast and ocean for environmentally sustainable and prudent use by current and future generations† (California Coastal Commission), to name just a couple. However, the proliferation of such agencies and programs has been insufficient to curb the negative effects of pollution and encroachment by humans on natural coastal habitats. According to an assessment of California’s coastal waters done in the year 2000, 98% of the state’s estuaries and bays were unable to fully support aquatic life, more than 90% carried warnings about eating fish and shellfish, and 86% could not support

Care of a Patient in Acute Pain from a Total Knee Replacement Jahaira Melendez Essay Example for Free

Care of a Patient in Acute Pain from a Total Knee Replacement Jahaira Melendez Essay Nursing care after a total knee replacement is very essential in promoting a speedy and safe recovery for a patient. In an attempt to replicate the knee’s natural ability to roll and glide as it bends by cutting away damaged bone and cartilage and replacing it with an artificial joint, acute pain following the procedure can be unbearable. In assisting the patient in controlling the pain would only guarantee the best recovery possible. With pain control, the patient will be able to perform follow up care and exercises to the best of their ability and over 90% of patients who undergo a total knee replacement have good results with recovery and ability to resume performing normal daily activities and minimizing the risks of complications to the surgical site. Keywords: Pain management, encouragement, total knee replacement, arthritis, prosthetic Care of a Patient in Acute Pain from a Total Knee Replacement A common medical condition seen in many aspects of the medical field is arthritis. Arthritis is the inflammation of a joint and the most common type of arthritis is osteoarthritis, also known as wear and tear. Pain from any medical condition or procedure can be very stressful to a patient and inhibit any recovery. Arthritis can be diagnosed by performing an x-ray to determine the extent of joint damage. Someone with arthritis of the knee usually has difficulty walking, climbing stairs and getting in and out of chairs. An orthopedic physician can recommend interventions. The most common joint replacement surgical intervention to help control and alleviate chronic pain for a patient is a Total Knee Replacement, also known as arthroplasty. A total knee replacement is performed to relieve moderate or severe pain and restore function in severely diseased knee joints. This procedure is not performed until pain is no longer controlled with non-operative treatment such as weight loss, activity modification, anti-inflammatory medications, joint supplements and cortisone injections. It is also not performed frequently on younger patients due to the implant wearing out quickly. An orthopedic physician would determine the type of prosthetic needed in order to achieve the most success. There are also modified implants to provide the best possible functioning with long lasting results such as partial knee, rotating knee, gender specific knee and custom knee. To perform the procedure, an orthopedic surgeon would administer general anesthesia, which means one is unconscious during operation, or spinal or epidural anesthesia in which a person is awake but cannot feel any pain from the waist down. During the procedure, the knee is in a bent position to fully expose the joint surfaces. An incision of 6 to 10 inches (15-25cm) is made on the front of the knee. The kneecap is moved aside and damaged surfaces are cut away. The femur is cut to match the corresponding surface of the metal femoral component that is placed on the end of the femur and the tibia is prepared with a flat cut on top to fit the metal and plastic tibial component that is inserted into the bone so the femoral component will slide as the knee is bent. If needed, the patella is cut flat and fitted with a plastic patella component and plastic spacers are inserted between the metal components for smooth gliding. Prior to completion, the knee is tested during surgery to ensure correct sizing and then closed with stitches or staples. The procedure would take 1 to 2 hours and recovery would be another 1 to 2 hours and then require a hospital stay of a couple of days. During the hospital stay, encouragement to move the foot and ankle to increase blood flow and prevent swelling or clots and blood thinners, support hoses or compression boots are very important. A nurse should also encourage the patient to cough regularly and take deep breaths to promote the movement of mucus that settles in the lungs during the procedure while being under anesthesia. Caring for a patient in acute pain after a procedure and managing pain levels is a very important part of recovery. Without pain control a patient will not be able to achieve recovery levels as quickly as possible without causing other injuries. Acute pain is related to tissue injury secondary to the surgical intervention. Upon discharge, teaching on follow up care is very important. A patient needs to know what to do and what to watch for as part of their recovery. Vital discharge instructions that a patient must be taught are: * When allowed to shower, usually 3 to 4 days after surgery, carefully wash incision with soap and water, rinse well and gently pat dry. Do no rub or apply creams. * Sit when showering to avoid falls. Avoid soaking to prevent infections. Try using non-slip mats, grab bars and elevated toilet seat or shower chair to prevent falls. Take pain medications as directed, do not double up doses if any doses are missed and do not drive when taking narcotics, usually about 6 weeks before it is ok to drive. * If taking a blood thinner, always verify with physician if it is ok to take Ibuprofen or any anti-inflammatory medications * Always sit in chairs with arms to make it easier to stand or sit but only 30 to 45 minutes at a time. * Sleep with pillow under ankle and keep knee straight but change leg position at night and nap if tired but don’t stay in bed all day. Wear support stockings for about 4 to 6 weeks and do not pivot, twist or kneel. * Walk up and down stairs with support, one step at a time using good knee to step up and bad knee to step down. As a fall prevention, always remove loose wires, throw rugs and have good lighting and keep items within reach. * Before and after any activity, ice the area for 30 minutes. Most importantly, teaching about potential risks such as nerve damage, stroke, and heart attack, blood clots in leg vein or lungs or infection should really be emphasized when discussing discharge instructions. Signs of infection would include increased redness, tenderness, swelling and pain of surgical site, stiffness, and fever with temperatures above 100 degrees Fahrenheit, shaking chills and drainage from site. If any of these symptoms occur, a call to the physician should be made immediately. Recovery will take several weeks during which time crutches or a walker will be needed and arrangements for transportation and everyday tasks will have to be made. Physical activity should be resumed slowly with normal household activities, a graduated walking program and knee strengthening exercises until staples or stitches are removed 2 to 3 weeks after surgery. Low impact exercising such as swimming or riding a stationary bicycle is tolerable but high impact activities such as running are not recommended due to an increased risk of joint failure because the knee joint components can loosen. During recovery from the surgical intervention, a nurses care to help control acute pain for the patient is one of the most important factors in helping a patient fully recover without further complications. Walking and knee movement begins soon after surgery so less pain would benefit the patient to move sooner and get strength back quickly. Pain control can be done with the use of analgesic and non-analgesic relief measures and reporting uncontrolled symptoms immediately. A nurse can assist with pain management interventions such as: * Performing comprehensive assessment of pain to include location, characteristics, onset, duration, frequency, quality, intensity or severity and precipitating factors. Always consider cultural differences and in non-verbal patient use the analog pain scale to evaluate pain control measures required * Reducing or eliminating increasing pain factors like fear or lack of knowledge * Teaching non pharmacological techniques like relaxation, massage, guided imagery and distraction * Checking vitals every 4 hours and neurovascular checks every hour during the first 12 to 24 hours then every 2 to 4 hours and always report any abnormal findings * Providing prescribed analgesics before activity to increase participation and assessing levels of comfort frequently * Initiating physical therapy, exercises and range of motion while teaching and reinforcing the use of techniques to prevent weight bearing on affected extremity and recommending home health or a rehabilitation facility * Monitoring incision bleeding, emptying and recording drainage every 4 hours and changing dressing every 24 to 48 hours * Encouraging increased fluid intake and high fiber diet, stool softener and a well-balanced diet with increased protein * Encouraging use of compression stockings to decrease swelling. Nursing care of a patient is very crucial in order to help the patient avoid potential complications with the prosthetic. An infected knee would require surgery to remove artificial parts and antibiotics to kill the bacteria then after clearing the infection another surgery would be required to install a new prosthetic. A nurse’s role in recovery is very important in many aspects of the patient’s care and the nurse can encourage and support the patient in building the confidence that they are able to perform the necessary steps to gain the ability to restore normal functions. Most importantly, helping the patient keep pain levels under control by whatever measures are comfortable to the patient should be first in mind. Pain can be the main factor that would prevent a patient from doing any follow care or treatment they are required to do in order to keep the prosthetic functioning adequately. The patient should be able to rely on the nurse to keep them in a comfortable state with the assistance of keeping in communication with the physician and without this patient-nurse relationship the patient would not be able to recover properly and achieve goals set as part of their recovery treatment plan.

Loss of Brain Nerve Cells in Alzheimers Disease

Loss of Brain Nerve Cells in Alzheimers Disease Fig-6: Showing neuronal death due to inflammation and oxidative stress. Adenosine Deaminase (ADA), and Neuropsychiatric Disorders:- Adenosine is a neuromodulator of brain function that is uniquely positioned to integrate excitatory and inhibitory neurotransmission and neuroprotective actions in pathological conditions. The understanding of adenosine production and release in the brain is therefore of fundamental importance and has been extensively studied (ADA-8). Adenosine metabolism in the brain is very important, and its dysregulation has been implicated in pathophysiology of several neuropsychiatric disorders, since it modulates the release of several neurotransmitters such as glutamate, dopamine, serotonin and acetylcholine, decreases neuronal activity by pos-synaptic hyperpolarization and inhibits dopaminergic activity. Adenosine deaminase participates in purine metabolism by converting adenosine into inosine (ADA-7). (The production and metabolism of adenosine is given in the Fig.7) Adenosine deaminase (ADA, adenosine aminohydrolase, EC 3.5.4.4), an enzyme involved in the metabolism of purine nucleosides, catalyses the irreversible hydrolytic deamination of adenosine (Ado) and 2 ´-deoxyadenosine (2 ´-dAdo) to inosine and 2 ´- deoxyinosine, respectively. The enzyme is widely distributed in vertebrate tissues and plays a critical role in a number of physiological systems. In nature, several isoforms of ADA are known that differ by molecular mass, kinetic properties and tissue distribution (ADA-2). It plays a role in the development and functioning of T lymphomonocytes. Levels of this enzyme increase during the mitogenic and antigenic response of lymphocytes, whereas ADA inhibitors limited the blastogenesis of lymphocytes; thus, ADA levels are higher in T cells than in B lymphocytes. ADA was previously recognized as a cytosolic enzyme; however, it is currently known to be present at the surfaces of cells, in particular T lymphocytes, to interact with some membrane proteins, including CD-26/DPP IV, and is considered an ecto-enzyme. This co-localization of DPP IV/CD-26 and ADA at T cells is important for the activation of T cells because the interaction of ADA and CD-26 at the T cells results in co-stimulatory signs responsible for the activation of the T cell receptor (ada ). Long considered to be an immune-privileged site because of the presence of the blood-brain-barrier (BBB) and the lack of a lymphatic system, it is now well-established that the brain is fully capable of mounting inflammatory responses in response to invading pathogens, trauma, or ischemic events (G-17). Fig. 7 Pathways of adenosine production, metabolism and transport, with indications of the sites of action of various enzyme inhibitors. Abbreviations are as follows: ADA, adenosine deaminase; AK, adenosine kinase; AOPCP, a,b-methylene ADP; DCF, deoxycoformycin; EHNA, erythro-9-(2-hydroxy-3-nonyl)adenosine; es, equilibrativesensitive nucleoside transporters; ei, equilibrative- insensitive nucleoside transporters; 5-IT, 5-iodotubercidin; NBMPR, nitrobenzylthioinosine; PDE, cAMP phosphodiesterase; SAH, S-adenosyl homocysteine. Activation of oligodendrocytes results in secretion of inflammatory molecules, such as nitric oxide (NO), cytokines, and prostaglandins and most  notably in upregulation of several chondroitin sulfate proteoglycans, including NG2, which contributes to the growth-inhibitory environment that prevents regeneration of axons in the injured CNS. In summary, in acute situations and when short lived, neuro-inflammatory mechanisms generally limit injury and promote healing; however, when neuro-inflammation becomes chronic it can damage viable host tissue, resulting in compromised neuronal survival and cognitive impairment. For these reasons, inflammation in the CNS has been appropriately described as a two-edged sword (G-17). Again Hcy activates cytokines and pro-inflammatory molecules, such as IL-1beta, IL-6, IL-12, IL-18, IL- 1 receptor antagonist, C-reactive protein, adhesion molecules (P-selectin, E-selectin, ICAM-1), and metalloproteinases (MMP-9). In addition, Hcy up-regulates reactive oxygen species, leading to activation of NF-kappa B, the pro-inflammatory nuclear regulatory molecule (G-3). On the other hand, neuropsychiatric disorders have been shown to be accompanied with some immune-inflammatory alterations. In this regard in order to make a contribution to the understanding of the ongoing immune disturbance in neuropsychiatric disorders, serum ADA activity was determined in neuropsychiatric patients and compared with healthy controls. Intracellular and extracellular levels of adenosine are tightly controlled by specific nucleoside transporters and several important enzymes, which include adenosine deaminase (ADA) and 5’-nucleotidase (5’-NT) (ADA-4). ADA activity is known to be increased in inflammatory diseases characterized by T-cell activation and proliferation. Therefore, ADA is considered a marker of T-cell activation. In addition, overproduction of reactive oxygen species (ROS) including hydrogen peroxide (H2O2), superoxide anion (Oà ¢- _ 2); nitric oxide (NOà ¢- ) and singlet oxygen (1O2) creates a condition known as oxidative stress, resulting in the amplification of the inflammatory response (ADA-6). Studies related to ADA levels in neuropsychiatric patients are virtually non-existent. ADA and schizophrenia Adenosine may play a role in the pathophysiology of schizophrenia, since it modulates the release of several neurotransmitters such as glutamate, dopamine, serotonin etc. Dutra GD et al (2009) showed that decreased ADA activity in schizophrenic patients than in control subjects (ADA-7). Brunstein MG et al (2007) reported that the schizophrenic patients treated either with typical antipsychotics or clozapine showed increased serum ADA activity compared to controls (ada-b sub 14). ADA and Depression Elgun et al (1999b) reported that decrease ADA activity in patients with depression compared with controls, might reflect the impaired immune system in depression (A sub). Mackiewicz et al (2006) showed that ADA levels did not change with age in rats (A sub). Herken H et al (2007) showed that ADA levels of the patients were significantly higher than the controls (abstract ref). An increasing body of evidence implicates both brain inflammation and oxidative stress in the pathogenesis of Alzheimers disease (A-9). Inflammation is a cause, contributor, or secondary phenomenon in the disorder inflammatory pathways are altered in the periphery in AD, together with evidence that increased peripheral inflammation leads to more neurodegeneration and accelerated disease progression in animal models. Antioxidants defense:- Humans have evolved a highly complicated antioxidant defense system to combat the damaging effects of free radicals. Under physiological conditions, overproduction of ROS and RNS and their neutralization is prevented by the activity of endogenous anti-oxidative defense system (AOS). Antioxidants are a broad group of compounds which constitute the first line of defense against free radical damage thus are essential for maintaining optimum health and well-being. They are protective agents, capable of stabilizing or deactivating free radicals before they attack cells. Being beneficial compounds, they control free radical formation naturally and help organisms to deal with oxidative stress caused by free radicals (antiox 4) (Fig. 8). Antioxidant system encloses enzymes like superoxide dismutase; catalase, glutathione peroxidase, and other antioxidant-regenerating enzymes such as gluthatione reductase; dehydroascorbate reductase and glucose-6 phosphate dehydrogenase, that maintains reduced NADPH; hydrophilic scavengers like urate, ascorbate, gluthatione, flavonoids; lipophilic scavengers, like tocopherols, carotenoids and ubiquinone. The great majority of antioxidants are supplied with the diet and includes polyphenols, lipoic and ascorbic acid, carotenoids, lycopene, quercetine, genstein, ellagic acid, ubiquinone and indole-3 carbinole. In fact, in the biological systems, the normal processes of oxidation produces highly reactive free radicals and each of this administered compounds is involved in the physiological redox balance preventing damage to the tissues (antioxi 3). Enzymatic Antioxidants An important part of the intracellular antioxidant defense systems are antioxidant enzymes such as superoxide dismutase, catalase and peroxidases. Superoxide dismutase (SOD) SOD is found abundantly in many organisms, from microorganisms to plant and animals, since superoxide radicals (O2−†¢) are toxic to living cells, oxidizing and degrading biologically important molecules, such as lipids and proteins. The role of SOD is to protect aerobic cells against O2−†¢ action. It catalyzes O2−†¢ dismutation reaction into H2O2 and O2−†¢. There are three known types of SOD: two copper-zinc containing SOD (CuZn-SOD), one in cytosol and one bound to the vascular endothelium ( also called â€Å"extracellular SOD† (ECSOD)) and a manganese containing SOD (MnSOD), which is localized in the mitochondrial matrix (antio-4). This enzyme specifically catalyzes the dismutation of O2−†¢ anion into H2O2 and O2−†¢ in a pH-independent medium (5–9.5). Manganese SOD is the mitochondrial form of this dismutase. Its active site contains manganese and reduces the O2−†¢ generated during the ETC. T he amount of MnSOD inside the cell varies according to the number of mitochondria found in each cell type. This enzyme has antitumor activity. Extracellular SOD also contains copper and zinc in its structure and is the main extracellular SOD. It is synthesized inside the cells and secreted into the extracellular matrix (G-66, G-71, SOD-1). Fig. 8- Mechanism of action of antioxidants Catalase (CAT) Catalase is an enzyme that reacts very effectively with H2O2 to form water and molecular oxygen and with H donors (methanol, ethanol, formic acid, or phenols) with peroxidase activity. Catalase protects cells against H2O2 generated inside them. Although CAT is not essential to some cell types under normal conditions, it has an important role in the acquisition of tolerance to ONS in cellular adaptive response (G-10). Glutathione peroxidase (GPx) and Glutathione Reductase GPx is an enzyme that contains a single selenocysteine (Sec) residue in each of four identical subunits, which are essential to the enzyme’s activity. Humans have four different GPx types: (1) a classic cytosolic form; (2) a membrane-associated GPx phospholipids, (3) another cytoplasmic enzyme, gastrointestinal GPx; and (4) an extracellular type. All GPx enzymes are known to add two electrons to reduce peroxides by selenols forming (Se-OH). GPx antioxidant properties allow them to eliminate peroxides as potential substrates for Fenton’s reaction. Glutathione peroxidase works together with glutathione tripeptide (GSH), which is present in cells in high (micromolar) concentrations. The substrate for the GPx catalytic reaction is H2O2 or organic peroxide ROOH. Glutathione peroxidase catalyzes hydroperoxide reduction using GSH, thus protecting mammalian cells against oxidative damage. Glutathione metabolism is one of the most important antioxidant defense mechanisms (G-10). Together with classic H2O2-removing enzymes (CAT and GSH-Px), the enzyme thioredoxin reductase (TrxR) is a seleno-flavoprotein which forms the thioredoxin system together with the protein thioredoxin (Trx) and NADPH. This is an effective system to reduce proteins in disulfide form and it also participates actively in the removal of H2O2 and other peroxides (G-57). 4) Thioredoxin reductase (TrxR) TrxR catalyzes the reduction of Trx especially, but in humans it can also reduce other substrates, such as vitamin C. This reductase also catalyzes the reduction of disulfide proteins and it is involved in countless vital processes, such as DNA synthesis and the regulation of apoptosis. Additionally, this system also donates electrons during DNA synthesis, and NADPH and human TrxR by themselves or with Trx are efficient electron donors to this human plasma peroxidase, which allows this enzyme to reduce hydroperoxides even when there are low levels of GSH available (G-52). There are three identified TrxR isoenzymes: cytosolic (TrxR-1), mitochondrial (TrxR-2), and a third isoenzyme which has been isolated from the mitochondrion of rat testes (TrxR-3). TrxR-1 has wide substrate specificity, since it is responsible for reducing not only Trx but also hydroperozides, lipoic acid, ubiquinone, and dehydroascorbate. Thus, the Trx system is regarded as having a crucial role maintaining a cell’s redox state. It may also have a role in the system which regulates the expression of redox-sensitive genes through the activation of transcription factors (G-58). Non-enzymatic Antioxidants Vitamin E (ÃŽ ±-tocopherol) The lipid-soluble antioxidant vitamin E is localized in the cell membrane and has been targeted for its relation to atherosclerosis and vascular function. Decreased concentration vitamin E (ÃŽ ±-tocopherol) scavenges the chain-carrying peroxyl radicals rapidly and interrupts the chain propagation. During this reaction, vitamin E becomes a free radical called tocopheryl, which is less reactive than the lipid radical and migrates to the surface of the membrane to be transformed again into tocopherol through the action of ascorbic acid (G-72) (Fig-9). However, in elevated concentrations the tocopheryl radical may act as pro-oxidant. On the other hand, ÃŽ ²-carotene is a hydrophilic precursor of vitamin A and large concentrations accumulate in the membranes of certain tissues. Its antioxidant activity is related to the removal of O2−†¢ and free radicals formed during lipid peroxidation. This activity is due to its conjugated double-bonded structure that can dislocate unpaired electrons, which enables ÃŽ ²-carotene to physically quench singlet oxygen without degradation (G-65). Vitamin C (ascorbic acid) Vitamin C is a hydrosoluble antioxidant, which facilitates its diffusion into intra- and extracellular matrices. Its antioxidant potential is related to direct removal of O2−†¢ and HO†¢. Furthermore, it contributes to regenerating oxidized vitamin E; however, vitamin C also has pro-oxidant activity. It may be the one compound, in addition to HO†¢, that can convert Fe3+ into Fe2+, which then reacts with H2O2 to form OH. Vitamin C is a water-soluble vitamin that participates in a large number of cell functions (antio 5). All

Model for Predicting Fatigue Life of Nanomaterials

Model for Predicting Fatigue Life of Nanomaterials Introduction In the past, the primary function of micro-systems packaging was to provide input/output (I/O) connections to and from integrated circuits (ICs) and to provide interconnection between the components on the system board level while physically supporting the electronic device and protecting the assembly from the environment. In order to increase the functionality and the miniaturization of the current electronic devices, these IC devices have not only incorporated more transistors but have also included more active and passive components on an individual chip. This has resulted in the emerging trend of a new convergent system[1] Currently, there are three main approaches to achieving these convergent systems, namely the system-on-chip (SOC), system-in-package (SIP) and system on package (SOP). SOC seeks to integrate numerous system functions on one silicon chip. However, this approach has numerous fundamental and economical limitations which include high fabrication costs and integration limits on wireless communications, which due to inherent losses of silicon and size restriction. SIP is a 3-D packaging approach, where vertical stacking of multi-chip modules is employed. Since all of the ICs in the stack are still limited to CMOS IC processing, the fundamental integration limitation of the SOC still remains. SOP on the other hand, seeks to achieve a highly integrated microminiaturized system on the package using silicon for transistor integration and package for RF, digital and optical integration[1] IC packaging is one of the key enabling technologies for microprocessor performance. As performance increases, technical challenges increase in the areas of power delivery, heat removal, I/O density and thermo-mechanical reliability. These are the most difficult challenges for improving performance and increasing integration, along with decreasing manufacturing cost. Chip-to-package interconnections in microsystems packages serve as electrical interconnections but often fail by mechanisms such as fatigue and creep. Furthermore, driven by the need for increase the system functionality and decrease the feature size, the International Technology Roadmap for Semi-conductors (ITRS) has predicted that integrated chip (IC) packages will have interconnections with I/O pitch of 90 nm by the year 2018 [2]. Lead-based solder materials have been used for interconnections in flip chip technology and the surface mount technology for many decades. The traditional lead-based and lead-free solder bumps will not satisfy the thermal mechanical requirement of these fine pitches interconnects. These electronic packages, even under normal operating conditions, can reach a temperature as high as 150C. Due to differences in the coefficient of thermal expansion of the materials in an IC package, the packages will experience significant thermal strains due to the mismatch, which in turn will cause lead and lead-free solder interconnections to fail prematurely. Aggarwal et al [3] had modeled the stress experienced by chip to package interconnect. In his work, he developed interconnects with a height of 15 to 50 micrometre on different substrate using classic beam theory. Figure 1 shows the schematic of his model and a summary of some of his results. Although compliant intrerconect could reduces the stress experienced by the interconnect, it is still in sufficient. Chng et al. [4] performed a parametric study on the fatigue life of a solder column for a pitch of 100micrometre using a macro-micro approach. In her work, she developed models of a solder column/bump with a pad size of 50micrometre and heights of 50 micrometre to 200 micrometre. Table I shows a summary of some of her results. Table 1.1: Fatigue life estimation of solder column chip thickness (micrometre) 250 640 640 640 board CTE (ppm/K) 18 18 10 5 solder column height (micrometre) Fatigue life estimation/cycle) 50 81 N.A 171 3237 100 150 27 276 3124 150 134 31 518 4405 200 74 38 273 5772 It can be seen from Table 1.1 that the fatigue lives of all solder columns are extremely short. Apart from the 5ppm/K board where there is excellent CTE matching, the largest fatigue life of the solder column is only about 518 cycles. As expected, the fatigue life increases significantly when the board CTE decreases from 18ppm/K to 10ppm/K and as the height increases from 50micrometre to 200micrometre.This is mainly due to the large strain induced by the thermal mismatch as shown in Figure 1.2. The maximum inelastic principal strain was about 0.16 which exceeds the maximum strain that the material can support. Although the fatigue life of the chip to package interconnection can be increases by increasing the interconnects height, it will not be able to meet the high frequency electrical requirements of the future IC where they need to be operating at a high frequencies of 10-20 GHz and a signal bandwidth of 20 Gbps, By definition, nanocrystalline materials are materials that have grain size less than 100nm and these materials are not new since nanocrystalline materials have been observed in several naturally-occurring specimens including seashells, bone, and tooth enamel [5, 6]. However, the nanocrystalline materials have been attracting a lot of research interest due to its superior mechanical and electrical properties as compared to the coarse-grained counterpart. For example, the nano-crystalline copper has about 6 times the strength of bulk copper [7]. Furthermore, the improvement in the mechanical properties due to the reduction in grain size has been well-documented. Increase in strength due to the reduction in grain-size is predicted by the Hall-Petch relationship which has also been confirmed numerically by Swygenhoven et al [8] and was first demonstrated experimentally by Weertman [9]. The implantation of nanocrystalline copper as interconnect materials seems to be feasible from the processing viewpoint too. Copper has been used as interconnects materials since 1989 whereas nano-copper has also been widely processed using electroplating and other severe plastic deformation techniques in the past few years. For instance, Lu et al. [10] have reported electroplating of nano-copper with grain size less than 100 nm and electrical conductivity comparable to microcrystalline copper. Furthermore, Aggarwal et al [11] have demonstrated the feasibility of using electrolytic plating processes to deposit nanocrystalline nickel as a back-end wafer compatible process. However, there are certain challenges regarding implantation of nanocrystalline copper as interconnects materials. As discussed above, nanocrystalline copper have a high potential of being used as the next generation interconnect for electronic packaging. However, it is vital to understand their material properties, deformation mechanisms and microstructures stability. Although the increase in strength due to the Hall-Petch relationship which has also been confirmed numerically and experimentally by Weertman [9], the improvement in the fatigue properties is not well documented and no model has been established to predict/characterize these nano materials in interconnection application; conflicting results regarding the fatigue properties have also been reported. Kumar et al [12] reported that for nano-crystalline and ultra-fine crystalline Ni, although there is an increase in tensile stress range and the endurance limit, the crack growth rate also increases. However, Bansal et al. [7] reported that with decreasing grain size, the tensile stress range increases but the crack growth rate decreases substantially at the same cyclic stress intensity range. Thus, nanostructured materials can potentially provide a solution for the reliability of low pitch interconnections. However, the fatigue resistance of nanostructured interconnections needs to be further investigated. Since grain boundaries in polycrystalline material increases the total energy of the system as compare to perfect single crystal, it will resulted in a driving force to reduce the overall grain boundary area by increasing the average grain size. In the case of nanocrystalline materials which have a high volume fraction of grain boundaries, there is a huge driving force for grain to growth and this presented a presents a significant obstacle to the processing and use of nanocrystalline copper for interconnect applications. Millet et al [13] have shown, though a series of systematic molecular dynamics simulations, grain growth in bulk nanocrystalline copper during annealing at constant temperature of 800K can be impeded with dopants segregated in the grain boundaries regions. However, it has been observed that stress can trigger grain growth in nanocrystalline materials [14] and there is no literature available on impeding stress assisted grain growth. There is an impending need to investigate the impediment to grain growth caused by the dopant during fatigue/stress assisted grain growth Dissertation Objectives The goal of present project is to develop a model for the fatigue resistance of nano-materials that have been shown to have superior fatigue resistance. Accordingly, the following research objectives are proposed. Develops a model for predicting fatigue life of nanostructured chip-to-package copper interconnections Develops a fundamental understanding on the fatigue behavior of nanocrystalline copper for interconnect application Addresses the issue on the stability of nanocrystalline materials undergoing cyclic loading Overview of the Thesis The thesis is organized so that past research on nanocrystalline materials forms the basis of the understanding and new knowledge discovered in this research. Chapter 2 reviews much of the pertinent literature regarding nanocrystalline materials, including synthesis, deformation mechanisms, and grain growth. Chapter 3 describes a detailed overview of the technical aspects of the molecular dynamics simulation method including inter-atomic potentials, time integration algorithms, the NVT NPT, and NEPT ensembles, as well as periodic boundary conditions and neighbor lists. Include in this chapter is the algorithms for creating nanocrystalline materials used in this dissertations.. Chapter 4 describes the simulation procedure designed to investigate and develop the long crack growth analysis. The results of the long crack growth analysis will be presented at the end of Chapter 4. Chapter 5 presents the result and discussion on mechanical behavior of single and nanocrystalline copper subjected to monotonic and cyclic loading whereas Chapter 6 presents the result and discussion on the impediment to grain growth caused by the dopant during fatigue/stress assisted grain growth. Finally, conclusions and recommendations for future work are presented in Chapter 5. Chapter 2 This chapter offers an expanded summary of the literature published with regards to the fabrication methods, characterization, and properties of nanocrystalline materials in addition to a description of existing interconnect technology. 2.1 Off-Chip Interconnect Technologies Chip-to-package interconnections in microsystems packages serve as electrical interconnections but they will often failed by mechanisms such as fatigue and creep. Furthermore, driven by the need for increase the system functionality and decrease the feature size, the International Technology Roadmap for Semi-conductors (ITRS) has predicted that interconnections of integrated chip (IC) packages will have a I/O pitch of 90 nm by the year 2018 [2]. The International Technology Roadmap for Semiconductors (ITRS) roadmap is a roadmap that semiconductor industry closely follows closely and its projects the need for several technology generations. The package must be capable of meeting these projections in order for it to be successful. This section reviews some of the current interconnect technology. Wire bonding [15] as shown in Figure 2.1, is generally considered as one of the most simple, cost-effective and flexible interconnect technology. The devices on the silicon die are (gold or aluminum) wire bonded to electrically connect from the chip to the wire bond pads on the periphery. However, the disadvantages of wire bonding are the slow rate, large pitch and long interconnect length and hence this will not be suitable for high I/O application. Instead of wires in the wire bonding, tape automated bonding (TAB) is an interconnect technology using a prefabricated perforated polyimide film, with copper leads between chip and substrate. The advantage of this technology is the high throughput and the high lead count. However, it is limited by the high initial costs for tooling. An alternative to peripheral interconnect technology is the area-array solution, as shown in Figure 2.3, that access the unused area by using the area under the chip. In area-array packaging, the chip has an array of solder bumps that are joined to a substrate. Under-fill is then fills the gap between the chip and substrate to enhance mechanical adhesion. This technology gives the highest packaging density methods and best electrical characteristics of all the avaiable interconnection technology. However, not only is its initial cost is high, it requires a very demanding technology to establish and operate. With the need for higher I/O density, compliant interconnects have been developed to satisfy the mechanical requirements of high performance micron sized interconnects. The basic idea is to reduce shear stress experienced by the interconnects through increasing their height or decreasing of its shear modulus (i.e. increases in their compliant) and hence the name compliant interconnects. Some of recent research in compliant interconnects include Tesseras Wide Area Vertical Expansion, Form Factors Wire on Wafer and Georgia Institute of Technologys Helix interconnects [17-19] as shown in Figure 2.4. Although compliant interconnects can solve the problem of mechanical reliability issue, they are done at the expense of the electrical performance. Since there is a need to reduce the packages parasitic through a decrease line delays, there is a need to minimize the electrical connection length in order to increase the system working frequency. Hence, compliant interconnect may not meet the high electrical frequency requirements of future devices. Figure 2.4: (a) Wide Area Vertical Expansion, (b) Wire on Wafer and (c) G-Helix [17-19] Lead and lead-free solders typically fail mechanical when scaled down to less than to a pitch of 100 mm. Compliant interconnections, on the other hand, do not meet the high frequency electrical requirements. The Microsystems Packaging Research Center at Georgia institute of Technology had demonstrated the feasibility of using re-workable nanostructure interconnections. Aggarwal et al [20] had show that nanostructured nickel interconnections, through a Flip Chip test vehicle, was able to improve the mechanical reliability while maintaining the shortest electrical connection length. However, the main disadvantages of this method was the significant signal loss at high frequency signal of nanocrystalline nickel [21]. As discussed above, nanostructure interconnects technology is the most promising interconnect technology to best meet the stringent mechanical and electrical requirement of next generation devices. However, there is a need of an alternate materials and a sensible choice of materials in this case would be nanocrystalline copper for its high strength material with superior electrical conductivity. Hence, it would be beneficial to use nanocrystalline-copper as material for the nanostructure interconnects. Due to the tendency for the grain to grow, there is a need to stabilize the grain growth in nanocrystalline copper before using it could be considered as a potential candidate for nanostructure interconnect. 2.2 Nanocrystalline material Nanocrystalline materials are polycrystalline materials with an average grain size of less than 100 nm [22]. Over the past decade , new nanocrystalline or nanostructured materials with key microstructural length scales on the order of a few tens of nanometers has been gaining a lot of interest in the material science research society. This is mainly due to its unique and superior properties, as compared to their microcrystalline counterparts which includes increased strength [22] and wear resistance [23]. These unique properties are due to the large volume fraction of atoms at or near the grain boundaries. As a result, these materials have unique properties that are representative of both the grain boundary surface characteristics and the bulk. Recent advances in synthesis and processing methodology for producing nanocrystalline materials such as inert gas condensation [24], mechanical milling [25, 26], electro-deposition [27], and severe plastic deformation [28] have made it possible to produce sufficient nanocrystalline materials for small scale application. 2.2.1 Synthesis Inert gas condensation, the first method used to synthesis bulk nanocrystalline [29], consists of evaporating a metal inside a high-vacuum chamber and then backfilling the chamber with inert gas [30]. These evaporated metal atoms would then collide with the gas atoms, causing them to lose kinetic energy and condenses into powder of small nano-crystals. These powders are then compacted under high pressure and vacuum into nearly fully dense nanocrystalline solids. The grain size distribution obtained from this method is usually very narrow. However, the major draws back of this method are its high porosity levels and imperfection bonding. Grain coarsening also occurs due to the high temperature during the compaction stage [31]. Mechanical milling consists of heavy cyclic deformation in powders until the final composition of the powders corresponds to a certain percentages of the respective initial constituents [25, 26]. A wide grain size distribution is obtained by this method. This technique is a popular method to prepare nanocrystalline materials because of its applicability to any material and simplicity. However, their main drawback includes contamination and grain coarsening during the consolidation stage. Electro-deposition consists of using electrical current to reduce cations of a desired material from a electrolyte solution and coating a conductive object on the substrate. Electro-deposition has many advantages over processing techniques and this includes its applicability to a wide variety of materials, low initial capital investment requirements and porosity-free finished products without a need for consolidation processing [27]. Furthermore, Shen et al. [32] and Lu et al.[33] had recently show that the right electro-deposition condition can produce a highly twinned structure which leads to enhanced ductility. The main drawback of this method is it is the difficulty to achieve high purity. Severe plastic deformation, such as high-pressure torsion, equal channel angular extrusion (ECAE), continuous confined shear straining and accumulative roll-bonding, uses extreme plastic straining to produce nanocrystalline materials by mechanisms such as grain fragmentation, dynamic recovery, and geometric re-crystallization [34]. It is the only technology that transformed conventional macro-grained metals directly into nanocrystalline materials without the need of potentially hazardous nano-sized powders. This is achieved by introducing very high shear deformations into the material under superimposed hydrostatic pressure. Two of the most commonly used methods are high-pressure torsion and ECAE [35]. In the study of the effect of ECAE on the microstructure of nanocrystalline copper, Dalla Torre et al [36] observed that the grains become more equi-axial and randomly orientation as the number of passes increases, as shown in Figure 2.5 Figure 2.5: Microstructure of ECAE copper subjected to (a) 1 passes (b) 2 passes (c) 4 passes (d) 8 passes (e) 12 passes and (f) 16 passes [36] 2.2.2 Mechanical Behavior of nanocrystalline materials Due to the small grain size and high volume fraction of grain boundaries, nanocrystalline materials exhibit significantly different properties and behavior as compared to their microcrystalline counterpart. The structure and mechanical behavior of nanocrystalline materials has been the subject of a lot of researchers interests both experimentally [37-43] and theoretically [44-50]. This section reviews the principal mechanical properties and behavior of nanocrystalline materials. 2.2.2.1 Strength and ductility Recent studies of nanocrystalline metals have shown that there is a five to ten fold increases in the strength and hardness as compared to their microcrystalline state [7, 36, 37, 51, 52]. This increase in the strength is due to the presence of grain boundaries impeding the nucleation and movement of dislocations. Since decreasing grain boundary size increases the number of barrier and the amount of applied stress necessary to move a dislocation across a grain boundary, this resulted in a much higher yield strength. The inverse relationship between grain size and strength is characterized by the Hall-Petch relationship [53, 54] as shown in equation (2.1). Eq (2.1) In equation (2.1), s is the mechanical strength, k is a material constant and d is the average grain size. Hence, nanocrystalline materials are expected to exhibit higher strength as compared to their microcrystalline counterpart. Figure 2.6 and Figure 2.7 show the summary of hardness and yield strength from tensile test that are reported in the literature. Indeed, hardness and yield strength of copper with a grain size of 10nm (3GPa) can be one order higher than their microcrystalline counterpart. To the larger specimens. Derivation from Hall-Petch relationship begins as the grain size approaches 30nm where the stresses needed to activate the dislocation multiplication via Frank-Read sources within the grains are too high and the plastic deformation is instead accommodated by grain boundaries sliding and migration.[12]. Furthermore, as the grain size reduces, the volume fraction of the grain boundaries and the triple points increases. Material properties will be more representative of the grain boundary activity [64] and this will resulting the strength to be inversely proportional to grain size instead of square roots of the grain size as predicted by Hall Petch relation [65]. Further reduction in the grain size will result in grain boundaries processes controlling the plastic deformation and reverse Hall-Petch effect, where the materials soften, will take place. Although sample defects had been account for the earlier experimental observation of reverse Hall-Petch effect[24], Swygenhoven et al [66] and Schiotz et al [47], using molecular simulation, was able to showed that nanocrystalline copper had the highest strength (about 2.3GPa ) at a grain size of 8nm and 10-15nm respectively. Conrad et al [67] pointed out that below this critical grain size, the mechanisms shifted to grain boundary-mediated from dislocation-mediated plasticity and this causes the material to become dependent on strain rate, temperature, Taylor orientation factor and presence of the type of dislocation. The yield stress of nanocrystalline copper was highly sensitive to strain rate even though it is a fcc materials. The strain rate sensitivity, m, in equation 2.2 a engineering parameter which measured the dependency of the strain rate and Figure 2.8 shows a summary of m as a function of grain size for copper specimen in the literature [51, 68-70]. Due to high localized dislocation activities at the grain boundaries which results in enhanced strain rate sensitivities in nanocrystalline materials, m increases drastically when the grain size is below 0.1 mm as shown in Figure 2.8. (2.2) Room temperature strain rate sensitivity was found to dependent on dislocation activities and grain boundaries diffusion [52, 71, 72]. Due to the negligible lattice diffusion at room temperature, the rate limiting process for microcrystalline copper was the gliding dislocation to cutting through forest dislocation, resulting in low strain rate sensitivities. However, due to the increasing presence of obstacles such as grain boundaries for nanocrystalline materials, the rate limiting process for smaller grain size was the interaction of dislocation and the grain boundaries, which is strain rate and temperature dependence. By considering the length scale of the dislocation and grain boundaries interaction, Cheng et al [52] proposed the following model for strain rate sensitivities . (2.3) z is the distance swept by the dislocation during activation, r is the dislocation density and a, a and b are the proportional factors. With this model, they will be able to predict higher strain rate sensitivities for nanocrystalline material produced by severe plastic deformation as compared to other technique. Since the twin boundaries in nanocrystalline or ultra fine grain copper served as a barriers for dislocation motion and nucleation which led to highly localized dislocations near the twin boundaries, the strain rate sensitivity of copper with high density of coherent twin boundaries was found to be higher than those without any twin boundaries [33]. Lastly, the increase enhanced strain rate sensitivity in nanocrystalline copper had been credited for it increases in strength and ductility. For example, Valiev et al [60] credited the enhanced strain rate sensitivity of 0.16 for the high ductility. In addition to a strong dependency on the strain rate, strength in nanocrystalline materials was also highly dependent on the temperature. Wang et al [73] observed that the yield strength for ultra fine grain copper with a grain size of 300nm increases from approximately 370MPa to 500MPa when the temperature reduces from room temperature to 77k. The authors attributed this increase in yield strength due to the absence of additional thermal deformation processes at 77k. This is consistent with Huang et al [74] observation where the temperature dependence of nanocrystalline copper with an increase in hardness of nanocrystalline copper with lowering the temperature is noted Ductility is another important characteristic of nanocrystalline materials. In microcrystalline materials, a reduction in grain size will increase the ductility due to the presence of grain boundaries acting as effective barriers to the propagation of micro-cracks[75]. However, nanocrystalline copper showed a lower strain to failure than that of their microcrystalline counterparts and this lacks in ductility was attributed to the presence of processing defects [76]. Recent advanced in processing of nanocrystalline materials offer materials with fairly good ductility in additional to ultra-high strength. Lu et al [10] reported that nanocrystalline copper with minimal flaw produced via electro-deposition had an elongation to fracture of 30%. Furthermore, Youssef et al [77] observed a 15.5% elongation to failure for defect free nanocrystalline copper produced via mechanical milling. Hence, it was possible for nanocrystalline copper to be both strong and ductile if the processing artifacts are minimized. The failure are usually consists of dimples several time larger than their grain size was normally found on the failure morphology of nanocrystalline materials and Kumar et al [78] presented the following model for initiation and hence the eventual failure of nanocrystalline materials. Furthermore, the presence of shear region was found to be due to shear localization since the ratio of strain hardening rate to prevailing stress was usually small [79, 80]. Figure 2.9: Schematic illustration of fracture in nanocrystalline material postulated by Kumar et al [78] 2.2.2.2 Creeps Nanocrystalline materials are expected to creep during room temperature. This is because Due to the higher fraction of grain boundaries and triple junctions, self diffusivity of nanocrystalline material had been shown to increase by an order of three as compared to microcrystalline copper [81]. Since creep behavior was dependent on grain size and diffusivity, with creep rate increases with an increase in diffusivity or a decrease in grain size, the creep temperature for nanocrystalline copper was known to be a small fraction of melting temperature (about 0.22 of its melting points). Furthermore, since creep had always been cited as one of the reason for grain size softening in nanocrystalline materials, creeps were other important mechanical properties of nanocrystalline materials that had been gaining a lot of researchers attention. Due to the high volume fraction of grain boundaries and enhanced diffusivity rate Model for Predicting Fatigue Life of Nanomaterials Model for Predicting Fatigue Life of Nanomaterials Introduction In the past, the primary function of micro-systems packaging was to provide input/output (I/O) connections to and from integrated circuits (ICs) and to provide interconnection between the components on the system board level while physically supporting the electronic device and protecting the assembly from the environment. In order to increase the functionality and the miniaturization of the current electronic devices, these IC devices have not only incorporated more transistors but have also included more active and passive components on an individual chip. This has resulted in the emerging trend of a new convergent system[1] Currently, there are three main approaches to achieving these convergent systems, namely the system-on-chip (SOC), system-in-package (SIP) and system on package (SOP). SOC seeks to integrate numerous system functions on one silicon chip. However, this approach has numerous fundamental and economical limitations which include high fabrication costs and integration limits on wireless communications, which due to inherent losses of silicon and size restriction. SIP is a 3-D packaging approach, where vertical stacking of multi-chip modules is employed. Since all of the ICs in the stack are still limited to CMOS IC processing, the fundamental integration limitation of the SOC still remains. SOP on the other hand, seeks to achieve a highly integrated microminiaturized system on the package using silicon for transistor integration and package for RF, digital and optical integration[1] IC packaging is one of the key enabling technologies for microprocessor performance. As performance increases, technical challenges increase in the areas of power delivery, heat removal, I/O density and thermo-mechanical reliability. These are the most difficult challenges for improving performance and increasing integration, along with decreasing manufacturing cost. Chip-to-package interconnections in microsystems packages serve as electrical interconnections but often fail by mechanisms such as fatigue and creep. Furthermore, driven by the need for increase the system functionality and decrease the feature size, the International Technology Roadmap for Semi-conductors (ITRS) has predicted that integrated chip (IC) packages will have interconnections with I/O pitch of 90 nm by the year 2018 [2]. Lead-based solder materials have been used for interconnections in flip chip technology and the surface mount technology for many decades. The traditional lead-based and lead-free solder bumps will not satisfy the thermal mechanical requirement of these fine pitches interconnects. These electronic packages, even under normal operating conditions, can reach a temperature as high as 150C. Due to differences in the coefficient of thermal expansion of the materials in an IC package, the packages will experience significant thermal strains due to the mismatch, which in turn will cause lead and lead-free solder interconnections to fail prematurely. Aggarwal et al [3] had modeled the stress experienced by chip to package interconnect. In his work, he developed interconnects with a height of 15 to 50 micrometre on different substrate using classic beam theory. Figure 1 shows the schematic of his model and a summary of some of his results. Although compliant intrerconect could reduces the stress experienced by the interconnect, it is still in sufficient. Chng et al. [4] performed a parametric study on the fatigue life of a solder column for a pitch of 100micrometre using a macro-micro approach. In her work, she developed models of a solder column/bump with a pad size of 50micrometre and heights of 50 micrometre to 200 micrometre. Table I shows a summary of some of her results. Table 1.1: Fatigue life estimation of solder column chip thickness (micrometre) 250 640 640 640 board CTE (ppm/K) 18 18 10 5 solder column height (micrometre) Fatigue life estimation/cycle) 50 81 N.A 171 3237 100 150 27 276 3124 150 134 31 518 4405 200 74 38 273 5772 It can be seen from Table 1.1 that the fatigue lives of all solder columns are extremely short. Apart from the 5ppm/K board where there is excellent CTE matching, the largest fatigue life of the solder column is only about 518 cycles. As expected, the fatigue life increases significantly when the board CTE decreases from 18ppm/K to 10ppm/K and as the height increases from 50micrometre to 200micrometre.This is mainly due to the large strain induced by the thermal mismatch as shown in Figure 1.2. The maximum inelastic principal strain was about 0.16 which exceeds the maximum strain that the material can support. Although the fatigue life of the chip to package interconnection can be increases by increasing the interconnects height, it will not be able to meet the high frequency electrical requirements of the future IC where they need to be operating at a high frequencies of 10-20 GHz and a signal bandwidth of 20 Gbps, By definition, nanocrystalline materials are materials that have grain size less than 100nm and these materials are not new since nanocrystalline materials have been observed in several naturally-occurring specimens including seashells, bone, and tooth enamel [5, 6]. However, the nanocrystalline materials have been attracting a lot of research interest due to its superior mechanical and electrical properties as compared to the coarse-grained counterpart. For example, the nano-crystalline copper has about 6 times the strength of bulk copper [7]. Furthermore, the improvement in the mechanical properties due to the reduction in grain size has been well-documented. Increase in strength due to the reduction in grain-size is predicted by the Hall-Petch relationship which has also been confirmed numerically by Swygenhoven et al [8] and was first demonstrated experimentally by Weertman [9]. The implantation of nanocrystalline copper as interconnect materials seems to be feasible from the processing viewpoint too. Copper has been used as interconnects materials since 1989 whereas nano-copper has also been widely processed using electroplating and other severe plastic deformation techniques in the past few years. For instance, Lu et al. [10] have reported electroplating of nano-copper with grain size less than 100 nm and electrical conductivity comparable to microcrystalline copper. Furthermore, Aggarwal et al [11] have demonstrated the feasibility of using electrolytic plating processes to deposit nanocrystalline nickel as a back-end wafer compatible process. However, there are certain challenges regarding implantation of nanocrystalline copper as interconnects materials. As discussed above, nanocrystalline copper have a high potential of being used as the next generation interconnect for electronic packaging. However, it is vital to understand their material properties, deformation mechanisms and microstructures stability. Although the increase in strength due to the Hall-Petch relationship which has also been confirmed numerically and experimentally by Weertman [9], the improvement in the fatigue properties is not well documented and no model has been established to predict/characterize these nano materials in interconnection application; conflicting results regarding the fatigue properties have also been reported. Kumar et al [12] reported that for nano-crystalline and ultra-fine crystalline Ni, although there is an increase in tensile stress range and the endurance limit, the crack growth rate also increases. However, Bansal et al. [7] reported that with decreasing grain size, the tensile stress range increases but the crack growth rate decreases substantially at the same cyclic stress intensity range. Thus, nanostructured materials can potentially provide a solution for the reliability of low pitch interconnections. However, the fatigue resistance of nanostructured interconnections needs to be further investigated. Since grain boundaries in polycrystalline material increases the total energy of the system as compare to perfect single crystal, it will resulted in a driving force to reduce the overall grain boundary area by increasing the average grain size. In the case of nanocrystalline materials which have a high volume fraction of grain boundaries, there is a huge driving force for grain to growth and this presented a presents a significant obstacle to the processing and use of nanocrystalline copper for interconnect applications. Millet et al [13] have shown, though a series of systematic molecular dynamics simulations, grain growth in bulk nanocrystalline copper during annealing at constant temperature of 800K can be impeded with dopants segregated in the grain boundaries regions. However, it has been observed that stress can trigger grain growth in nanocrystalline materials [14] and there is no literature available on impeding stress assisted grain growth. There is an impending need to investigate the impediment to grain growth caused by the dopant during fatigue/stress assisted grain growth Dissertation Objectives The goal of present project is to develop a model for the fatigue resistance of nano-materials that have been shown to have superior fatigue resistance. Accordingly, the following research objectives are proposed. Develops a model for predicting fatigue life of nanostructured chip-to-package copper interconnections Develops a fundamental understanding on the fatigue behavior of nanocrystalline copper for interconnect application Addresses the issue on the stability of nanocrystalline materials undergoing cyclic loading Overview of the Thesis The thesis is organized so that past research on nanocrystalline materials forms the basis of the understanding and new knowledge discovered in this research. Chapter 2 reviews much of the pertinent literature regarding nanocrystalline materials, including synthesis, deformation mechanisms, and grain growth. Chapter 3 describes a detailed overview of the technical aspects of the molecular dynamics simulation method including inter-atomic potentials, time integration algorithms, the NVT NPT, and NEPT ensembles, as well as periodic boundary conditions and neighbor lists. Include in this chapter is the algorithms for creating nanocrystalline materials used in this dissertations.. Chapter 4 describes the simulation procedure designed to investigate and develop the long crack growth analysis. The results of the long crack growth analysis will be presented at the end of Chapter 4. Chapter 5 presents the result and discussion on mechanical behavior of single and nanocrystalline copper subjected to monotonic and cyclic loading whereas Chapter 6 presents the result and discussion on the impediment to grain growth caused by the dopant during fatigue/stress assisted grain growth. Finally, conclusions and recommendations for future work are presented in Chapter 5. Chapter 2 This chapter offers an expanded summary of the literature published with regards to the fabrication methods, characterization, and properties of nanocrystalline materials in addition to a description of existing interconnect technology. 2.1 Off-Chip Interconnect Technologies Chip-to-package interconnections in microsystems packages serve as electrical interconnections but they will often failed by mechanisms such as fatigue and creep. Furthermore, driven by the need for increase the system functionality and decrease the feature size, the International Technology Roadmap for Semi-conductors (ITRS) has predicted that interconnections of integrated chip (IC) packages will have a I/O pitch of 90 nm by the year 2018 [2]. The International Technology Roadmap for Semiconductors (ITRS) roadmap is a roadmap that semiconductor industry closely follows closely and its projects the need for several technology generations. The package must be capable of meeting these projections in order for it to be successful. This section reviews some of the current interconnect technology. Wire bonding [15] as shown in Figure 2.1, is generally considered as one of the most simple, cost-effective and flexible interconnect technology. The devices on the silicon die are (gold or aluminum) wire bonded to electrically connect from the chip to the wire bond pads on the periphery. However, the disadvantages of wire bonding are the slow rate, large pitch and long interconnect length and hence this will not be suitable for high I/O application. Instead of wires in the wire bonding, tape automated bonding (TAB) is an interconnect technology using a prefabricated perforated polyimide film, with copper leads between chip and substrate. The advantage of this technology is the high throughput and the high lead count. However, it is limited by the high initial costs for tooling. An alternative to peripheral interconnect technology is the area-array solution, as shown in Figure 2.3, that access the unused area by using the area under the chip. In area-array packaging, the chip has an array of solder bumps that are joined to a substrate. Under-fill is then fills the gap between the chip and substrate to enhance mechanical adhesion. This technology gives the highest packaging density methods and best electrical characteristics of all the avaiable interconnection technology. However, not only is its initial cost is high, it requires a very demanding technology to establish and operate. With the need for higher I/O density, compliant interconnects have been developed to satisfy the mechanical requirements of high performance micron sized interconnects. The basic idea is to reduce shear stress experienced by the interconnects through increasing their height or decreasing of its shear modulus (i.e. increases in their compliant) and hence the name compliant interconnects. Some of recent research in compliant interconnects include Tesseras Wide Area Vertical Expansion, Form Factors Wire on Wafer and Georgia Institute of Technologys Helix interconnects [17-19] as shown in Figure 2.4. Although compliant interconnects can solve the problem of mechanical reliability issue, they are done at the expense of the electrical performance. Since there is a need to reduce the packages parasitic through a decrease line delays, there is a need to minimize the electrical connection length in order to increase the system working frequency. Hence, compliant interconnect may not meet the high electrical frequency requirements of future devices. Figure 2.4: (a) Wide Area Vertical Expansion, (b) Wire on Wafer and (c) G-Helix [17-19] Lead and lead-free solders typically fail mechanical when scaled down to less than to a pitch of 100 mm. Compliant interconnections, on the other hand, do not meet the high frequency electrical requirements. The Microsystems Packaging Research Center at Georgia institute of Technology had demonstrated the feasibility of using re-workable nanostructure interconnections. Aggarwal et al [20] had show that nanostructured nickel interconnections, through a Flip Chip test vehicle, was able to improve the mechanical reliability while maintaining the shortest electrical connection length. However, the main disadvantages of this method was the significant signal loss at high frequency signal of nanocrystalline nickel [21]. As discussed above, nanostructure interconnects technology is the most promising interconnect technology to best meet the stringent mechanical and electrical requirement of next generation devices. However, there is a need of an alternate materials and a sensible choice of materials in this case would be nanocrystalline copper for its high strength material with superior electrical conductivity. Hence, it would be beneficial to use nanocrystalline-copper as material for the nanostructure interconnects. Due to the tendency for the grain to grow, there is a need to stabilize the grain growth in nanocrystalline copper before using it could be considered as a potential candidate for nanostructure interconnect. 2.2 Nanocrystalline material Nanocrystalline materials are polycrystalline materials with an average grain size of less than 100 nm [22]. Over the past decade , new nanocrystalline or nanostructured materials with key microstructural length scales on the order of a few tens of nanometers has been gaining a lot of interest in the material science research society. This is mainly due to its unique and superior properties, as compared to their microcrystalline counterparts which includes increased strength [22] and wear resistance [23]. These unique properties are due to the large volume fraction of atoms at or near the grain boundaries. As a result, these materials have unique properties that are representative of both the grain boundary surface characteristics and the bulk. Recent advances in synthesis and processing methodology for producing nanocrystalline materials such as inert gas condensation [24], mechanical milling [25, 26], electro-deposition [27], and severe plastic deformation [28] have made it possible to produce sufficient nanocrystalline materials for small scale application. 2.2.1 Synthesis Inert gas condensation, the first method used to synthesis bulk nanocrystalline [29], consists of evaporating a metal inside a high-vacuum chamber and then backfilling the chamber with inert gas [30]. These evaporated metal atoms would then collide with the gas atoms, causing them to lose kinetic energy and condenses into powder of small nano-crystals. These powders are then compacted under high pressure and vacuum into nearly fully dense nanocrystalline solids. The grain size distribution obtained from this method is usually very narrow. However, the major draws back of this method are its high porosity levels and imperfection bonding. Grain coarsening also occurs due to the high temperature during the compaction stage [31]. Mechanical milling consists of heavy cyclic deformation in powders until the final composition of the powders corresponds to a certain percentages of the respective initial constituents [25, 26]. A wide grain size distribution is obtained by this method. This technique is a popular method to prepare nanocrystalline materials because of its applicability to any material and simplicity. However, their main drawback includes contamination and grain coarsening during the consolidation stage. Electro-deposition consists of using electrical current to reduce cations of a desired material from a electrolyte solution and coating a conductive object on the substrate. Electro-deposition has many advantages over processing techniques and this includes its applicability to a wide variety of materials, low initial capital investment requirements and porosity-free finished products without a need for consolidation processing [27]. Furthermore, Shen et al. [32] and Lu et al.[33] had recently show that the right electro-deposition condition can produce a highly twinned structure which leads to enhanced ductility. The main drawback of this method is it is the difficulty to achieve high purity. Severe plastic deformation, such as high-pressure torsion, equal channel angular extrusion (ECAE), continuous confined shear straining and accumulative roll-bonding, uses extreme plastic straining to produce nanocrystalline materials by mechanisms such as grain fragmentation, dynamic recovery, and geometric re-crystallization [34]. It is the only technology that transformed conventional macro-grained metals directly into nanocrystalline materials without the need of potentially hazardous nano-sized powders. This is achieved by introducing very high shear deformations into the material under superimposed hydrostatic pressure. Two of the most commonly used methods are high-pressure torsion and ECAE [35]. In the study of the effect of ECAE on the microstructure of nanocrystalline copper, Dalla Torre et al [36] observed that the grains become more equi-axial and randomly orientation as the number of passes increases, as shown in Figure 2.5 Figure 2.5: Microstructure of ECAE copper subjected to (a) 1 passes (b) 2 passes (c) 4 passes (d) 8 passes (e) 12 passes and (f) 16 passes [36] 2.2.2 Mechanical Behavior of nanocrystalline materials Due to the small grain size and high volume fraction of grain boundaries, nanocrystalline materials exhibit significantly different properties and behavior as compared to their microcrystalline counterpart. The structure and mechanical behavior of nanocrystalline materials has been the subject of a lot of researchers interests both experimentally [37-43] and theoretically [44-50]. This section reviews the principal mechanical properties and behavior of nanocrystalline materials. 2.2.2.1 Strength and ductility Recent studies of nanocrystalline metals have shown that there is a five to ten fold increases in the strength and hardness as compared to their microcrystalline state [7, 36, 37, 51, 52]. This increase in the strength is due to the presence of grain boundaries impeding the nucleation and movement of dislocations. Since decreasing grain boundary size increases the number of barrier and the amount of applied stress necessary to move a dislocation across a grain boundary, this resulted in a much higher yield strength. The inverse relationship between grain size and strength is characterized by the Hall-Petch relationship [53, 54] as shown in equation (2.1). Eq (2.1) In equation (2.1), s is the mechanical strength, k is a material constant and d is the average grain size. Hence, nanocrystalline materials are expected to exhibit higher strength as compared to their microcrystalline counterpart. Figure 2.6 and Figure 2.7 show the summary of hardness and yield strength from tensile test that are reported in the literature. Indeed, hardness and yield strength of copper with a grain size of 10nm (3GPa) can be one order higher than their microcrystalline counterpart. To the larger specimens. Derivation from Hall-Petch relationship begins as the grain size approaches 30nm where the stresses needed to activate the dislocation multiplication via Frank-Read sources within the grains are too high and the plastic deformation is instead accommodated by grain boundaries sliding and migration.[12]. Furthermore, as the grain size reduces, the volume fraction of the grain boundaries and the triple points increases. Material properties will be more representative of the grain boundary activity [64] and this will resulting the strength to be inversely proportional to grain size instead of square roots of the grain size as predicted by Hall Petch relation [65]. Further reduction in the grain size will result in grain boundaries processes controlling the plastic deformation and reverse Hall-Petch effect, where the materials soften, will take place. Although sample defects had been account for the earlier experimental observation of reverse Hall-Petch effect[24], Swygenhoven et al [66] and Schiotz et al [47], using molecular simulation, was able to showed that nanocrystalline copper had the highest strength (about 2.3GPa ) at a grain size of 8nm and 10-15nm respectively. Conrad et al [67] pointed out that below this critical grain size, the mechanisms shifted to grain boundary-mediated from dislocation-mediated plasticity and this causes the material to become dependent on strain rate, temperature, Taylor orientation factor and presence of the type of dislocation. The yield stress of nanocrystalline copper was highly sensitive to strain rate even though it is a fcc materials. The strain rate sensitivity, m, in equation 2.2 a engineering parameter which measured the dependency of the strain rate and Figure 2.8 shows a summary of m as a function of grain size for copper specimen in the literature [51, 68-70]. Due to high localized dislocation activities at the grain boundaries which results in enhanced strain rate sensitivities in nanocrystalline materials, m increases drastically when the grain size is below 0.1 mm as shown in Figure 2.8. (2.2) Room temperature strain rate sensitivity was found to dependent on dislocation activities and grain boundaries diffusion [52, 71, 72]. Due to the negligible lattice diffusion at room temperature, the rate limiting process for microcrystalline copper was the gliding dislocation to cutting through forest dislocation, resulting in low strain rate sensitivities. However, due to the increasing presence of obstacles such as grain boundaries for nanocrystalline materials, the rate limiting process for smaller grain size was the interaction of dislocation and the grain boundaries, which is strain rate and temperature dependence. By considering the length scale of the dislocation and grain boundaries interaction, Cheng et al [52] proposed the following model for strain rate sensitivities . (2.3) z is the distance swept by the dislocation during activation, r is the dislocation density and a, a and b are the proportional factors. With this model, they will be able to predict higher strain rate sensitivities for nanocrystalline material produced by severe plastic deformation as compared to other technique. Since the twin boundaries in nanocrystalline or ultra fine grain copper served as a barriers for dislocation motion and nucleation which led to highly localized dislocations near the twin boundaries, the strain rate sensitivity of copper with high density of coherent twin boundaries was found to be higher than those without any twin boundaries [33]. Lastly, the increase enhanced strain rate sensitivity in nanocrystalline copper had been credited for it increases in strength and ductility. For example, Valiev et al [60] credited the enhanced strain rate sensitivity of 0.16 for the high ductility. In addition to a strong dependency on the strain rate, strength in nanocrystalline materials was also highly dependent on the temperature. Wang et al [73] observed that the yield strength for ultra fine grain copper with a grain size of 300nm increases from approximately 370MPa to 500MPa when the temperature reduces from room temperature to 77k. The authors attributed this increase in yield strength due to the absence of additional thermal deformation processes at 77k. This is consistent with Huang et al [74] observation where the temperature dependence of nanocrystalline copper with an increase in hardness of nanocrystalline copper with lowering the temperature is noted Ductility is another important characteristic of nanocrystalline materials. In microcrystalline materials, a reduction in grain size will increase the ductility due to the presence of grain boundaries acting as effective barriers to the propagation of micro-cracks[75]. However, nanocrystalline copper showed a lower strain to failure than that of their microcrystalline counterparts and this lacks in ductility was attributed to the presence of processing defects [76]. Recent advanced in processing of nanocrystalline materials offer materials with fairly good ductility in additional to ultra-high strength. Lu et al [10] reported that nanocrystalline copper with minimal flaw produced via electro-deposition had an elongation to fracture of 30%. Furthermore, Youssef et al [77] observed a 15.5% elongation to failure for defect free nanocrystalline copper produced via mechanical milling. Hence, it was possible for nanocrystalline copper to be both strong and ductile if the processing artifacts are minimized. The failure are usually consists of dimples several time larger than their grain size was normally found on the failure morphology of nanocrystalline materials and Kumar et al [78] presented the following model for initiation and hence the eventual failure of nanocrystalline materials. Furthermore, the presence of shear region was found to be due to shear localization since the ratio of strain hardening rate to prevailing stress was usually small [79, 80]. Figure 2.9: Schematic illustration of fracture in nanocrystalline material postulated by Kumar et al [78] 2.2.2.2 Creeps Nanocrystalline materials are expected to creep during room temperature. This is because Due to the higher fraction of grain boundaries and triple junctions, self diffusivity of nanocrystalline material had been shown to increase by an order of three as compared to microcrystalline copper [81]. Since creep behavior was dependent on grain size and diffusivity, with creep rate increases with an increase in diffusivity or a decrease in grain size, the creep temperature for nanocrystalline copper was known to be a small fraction of melting temperature (about 0.22 of its melting points). Furthermore, since creep had always been cited as one of the reason for grain size softening in nanocrystalline materials, creeps were other important mechanical properties of nanocrystalline materials that had been gaining a lot of researchers attention. Due to the high volume fraction of grain boundaries and enhanced diffusivity rate