Semiconductors are solid materials that have an electrical conductivity that varies over a wide range between that of conductors and that of insulators. This is clearly stated by the name itself used to describe such material, which is composed of two words-semi and conductor. Semi means partially while conductor refers to something that can conduct electricity. External means can also be utilized to change the electrical charge carrier density of semiconductors.
The electrical conductivity of these materials is a result of the charges of both signs. Semiconductor, 1552) The following paper aims to provide better understanding of semiconductors. A specific objective of the following paper is to be able to show the global challenges encountered in the semiconductor industry. Semiconductors have many uses in technology as these materials become essential in this day and age in almost all modern electrical devices. Combining different types of semiconductors creates devices that have special electrical properties – properties that permit the control of electrical signals.
Some devices used today that employ the use of semiconductors are computers, radios, cellular phones and digital audio players. Semiconductors are also used in the creation of various devices used in the medical field. There are two main classifications of semiconductors: intrinsic and extrinsic. The type that is chemically very pure and is a poor conductor falls under the intrinsic semiconductor material classification. These intrinsic semiconductors possess equal numbers of negative carriers and positive carriers.
While the extrinsic semiconductor is an upgraded version of intrinsic semiconductors as it has added varied quantities of impurities, a process known as doping. This process improves semiconductor conductivity by changing its electrical properties. The addition of impurities controls the conductivity. The electrical conductivity of a semiconductor is modified by many orders of magnitude through doping with foreign atoms.
For example, electron conduction is improved when a phosphorus atom – housing five valence electrons – becomes an electron donor to the conduction band when utilized as a replacement of a silicon host atom housing four valence electrons. (Queisser & Haller, 945) The fact that conductivity can be altered with the addition of impurities makes semiconductors highly important in the field of engineering. The fact that semiconductors can be conductors as well as insulators also lend to their importance in engineering.
Some of the earlier challenges to the experimentation of semiconductors had the mechanisms of doping at their roots. Experiments were hindered because of the electronic property’s high sensitivity to diminutive concentrations of impurities. Through persistent effort, these problems were resolved and impurity doping was perfected. Doping is now part of reproducible technology utilized to control the precision of electrical conductivity, composition, and minority-carrier lifetimes over extensive ranges. (Queisser & Haller, 945)
Observed defects and problematic issues of semiconductors will maintain scientific and technical interest. These defects may have a variation of electrical, optical, and structural properties. The main challenges in the science and technology of semiconductors lie in new forms of semiconductors, new hetero-interfaces, and new device structures from which semiconductor defects arise. Semiconductor properties need to be understood and scrutinized in order to effectively get rid of defects or, as with doping, in order to be able to effectively use the implied benefits of these defects.
Technology-wise, semiconductors continue to pose a challenge to the global community in that the decreasing dimensions of the structures of semiconductors will necessitate characterization tools of ever increasing sensitivity and selectivity. (Queisser & Haller, 949) Many other individuals involved with the development and study of semiconductors have also noted the challenges that the physical aspects of the technology pose. One example can be seen in the silicon chip, which is an electronic devised composed of tiny crystals of a silicon semiconductor developed to conduct a variety of electronic functions in a given integrated circuit.
The actual physical barriers in this form of semiconductor technology lie in the availability of the materials as well as in the control of the lithography utilized in creating the patterns on the chips. (Normille, 787) These types of problems threaten the predictions of Moore’s Law. This is a law that states that transistor performance and density multiply by a factor of two every three years. This was not so much a law as a prediction on the part of Gordon Moore, Intel co-founder, that the number of transistors on manufactured chips would double every 18 months implying a price decrease and a performance increase.
This prediction is referred to as a law because of the fact that so far its terms have not been violated. However, institutions such as the International Technology Roadman for Semiconductors also predict potential challenges to the semiconductor industry that threaten its progress. (Normille, 787) Advances in the industry that are required to decrease half the space between memory chip cells –also the DRAM half pitch – are termed as technology nodes and are continuously explored and projected by the industry in order to assess the heightening challenge in semiconductors.
The need to place more transistors in the same space has to be solved through a decrease in the DRAM half pitch, the increasing demands of which the manufacturers of semiconductors are questionable in the probability of being achieved in the timeline indicated. There are problems with how grain sizes can be reduced to the nanometer specifications needed in such a short time frame. Issues of the applicability and the appropriateness of lithography methods to be applied are also posing challenges to the industry. (Normille, 787) How then are manufacturers continuing with semiconductor technology despite the challenges these issues pose?
Manufacturers have achieved the increase of transistors in chips of the same space by scaling every feature of an integrated circuit in approximately equal proportions. However, it is undeniable that continuation of this practice will lead to an ultimate brick wall. One feature of semiconductor chips, the gate oxide, will, with the scaling methodology, become so thin that it will disappear completely as a result. (Normille, 787) The gate oxide is a material layer that stands between the semiconductor chip’s gate electrode, which is responsible for the control of electron flow, and the channel through which the current flows.
Essentially, it is a wall that insures that the electrons continue to move down their assigned path. With a continued decrease in the gate oxide’s thickness, the electron flow is more likely to leak away from the proper path and move down a new and incorrect path causing numerous malfunctions and problems in the chip. As Normille (787) stated, continued scaling will lead to effective disappearance of the gate oxide. Upon the occurrence of this event, scaling will have effectively come to its definite end as an applicable practice in semiconductor production.
It should be noted that the scaling of the gate control is not the only issue involved with the scaling method. The transistor is also at risk with continued dependence on scaling. The scaling of the transistor involves the concentration increase of donor atoms as well as of acceptor atoms. This allows the source to maintain a constant total charge and also allows the draining of regions. However, the concentrations required for the present technologies have reached the solid solubility limit of the dopant atoms. Newer types of dopant atoms have been assessed for replacement of present atoms being used.
However, none have been found that can produce mobile charges of higher concentrations. This means that transistor scaling is also facing the possibility of arriving at a dead end. Without further development of new methods, transistor scaling in the future will produce a total charge loss, resistance increase, and overall performance decrease. This shows that the challenge faced by semiconductor technology is in the development and conceptualization of new and more effective methods to manufacture these materials.
Present methods can not be maintained and are not stable in the results they will yield. There is a need to be able to better understand how to enhance the manipulation of the properties of semiconductors as well as of the different materials and characteristics involved in the manufacturing of semiconductor chips such as transistors, gate oxide and the like. The creation, for example, of a three-terminal transistor paired with a three atom thick gate oxide provided results that were comparable to the increased efficiency that is produced by scaling methods.
The sampling of different materials to be used for gate oxides such as zirconium and hafnium is also being conducted. The possibilities of different gating mechanisms are also being explored. (Normille, 787) These steps and their results, however, lead only to a temporary solution to the greater challenge of replacing the scaling methods of the industry. Although a replacement of the conventional silicon oxide with a more efficient material may extend the usability of scaling, it will not eliminate the inevitable result. The problem is not only in the materials being used or in the type of products being developed.
The challenge is in the creation of a new method The challenge is in the obvious end result facing all involved in semiconductor technology – that scaling will become obsolete. An additional challenge to semiconductor technology is the issue of time. Although the need for more efficient processes in the semiconductor industry is clear, there is also a set deadline for the development of these new processes. If the conceptualization of more efficient methods cannot be completed on time, semiconductor manufacturing will hit a production block.
There will be a stand still in the improvement of semiconductors. A stand still in the fast-paced progress of semiconductors could well stretch on for an undetermined length of time. This could prove to be detrimental to a great number of sectors of society such as engineering and medicine whose functions and utilized devices rely highly on the continuing improvement of semiconductors. There is hope, however, that an increased comprehension of charge and heat transport in the field of engineering could lead to more efficient semiconductor nanostructures.
Nanotechnology seems to be the next step in the evolution of the semiconductor. There has been no clear solution, however, to the issues plaguing semiconductor development. It is clear, at this point, that as far as science, technology, and engineering are concerned, the greatest challenge of semiconductors lies in the maintenance of Moore’s Law as well as in the continuation of the progress achieved in the previous years. The other challenges that might be identified outside of the scaling methodology will most likely be derivations of the bigger challenge posed by Moore’s law.
This is not to say, however, that challenges derived from Moore’s law are the only challenges faced by the semiconductor industry. On the contrary, at the present time one of the biggest challenges facing the semiconductor industry, also known today as the computer chip industry, are the health risks and concerns involved with the actual manufacture of semiconductor chips. Numerous health-related cases can be found documented in the legal system as actions of workers against companies manufacturing computer chips.
This section will delve into this topic and try to understand the merits of these claims as well as the implications health risks will have on the semiconductor industry. The manufacture of semiconductor chips has always included a long list of heavy metals and other toxic solvents. Some of these include hydrochloric acid, arsenic, cadmium, lead, methyl chloroform, toluene, benzene, acetone, trichloroethylene, and arsine. (Chepesiuk, A454) Debates rage between those studying the effects of the substances used in chip manufacture and those involved with the manufacture process itself such as the Semiconductor Industry Association.
Researchers state that the clean rooms, where semiconductors are located, may be cause for concern. Semiconductors require a dust-free environment. However, these clean rooms, safe for the semiconductor chips, may be potentially harmful to the workers having to come in to direct contact with them on a daily basis. (Tenenbaum, 282) They may pose a challenge to the semiconductor industry in that these issues of health may result in a negative image for the industry which will affect the market for the chips which in turn will affect the funding behind the drive for development of the semiconductor.
Clean rooms were designed to keep the dust particle count in the air of the room as low as possible. However, according to researchers, this meant that almost all of the air in the clean room is recycled air. Vapors and fumes from the different solvents found in the clean room are thus circulated again and again in the room without mechanisms of filtration out of the room. This meant a decrease in the safety of these rooms for the workers entering them to work on the semiconductors. The clean room thus becomes a lethal chemical laboratory of toxic fumes to which the employees are exposed. (Tenenbaum, 282)
The health risk posed by semiconductor manufacturing lies in the fact that the chemicals used range in the hundreds in number and the effects these have individually as well as together on the human system is highly unknown. The main routes these chemicals may take in attacking the health of an individual are through inhalation and through dermal exposures. Another problem in the health debate is the fact that the daily exposure to these chemicals results in an incremental effect on the body. This means that the changes it causes in the health of the worker is barely detectable as it only slowly adds up every day.
However, that is not to say that there is in fact a resulting decrease in health of the workers. It may well be the case that the semiconductor industry is free and guiltless of the blames assigned to it by its numerous critis. Defenders of the semiconductor industry state that the manufacturing process is made to best insure the safety of the workers. All chemicals and gases that are considered harmful and hazardous to human health are put in isolation in order to best insure that workers are not exposed to them and also to insure that contact with these substances are done in a controlled environment.
The clean room, according to the Semiconductor Industry Association, is made safe from chemical vapors and fumes through the processes of dilution and exhaust mechanisms. The association even claims that the amount of fresh air present in semiconductor clean rooms is even greater than the amount of fresh air present in other indoor manufacturing locales. (Tenenbaum, 282) Although health risks and occupational hazards have been studied and continuously shown to be average, sometimes less than average, by the semiconductor industry, there are still many who argue its lethal nature.
There have been studies showing increased miscarriages in female clean room workers. The industry actively stopped the growing concern regarding these findings by discontinuing the use of the supposed chemicals behind the miscarriages. Cancer has also been a health problem linked by researchers to the computer chip industry. These findings were countered by the semiconductor industry as being baseless as they did not find relationships between cancer and the industry’s materials. Tenenbaum, 282) This is however, questionable as most of the chemicals used in the manufacture of semiconductors are, in fact, known as probable human carcinogens. (Chepesiuk, A454)
The attacks against the semiconductor industry are persistent and, in a way, seem to be valid with their arguments. Despite the claims of the Semiconductor Industry Associaton, statistics from the U. S. Department of Labor’s Bureau of Labor Statistics show that workers from the semiconductor industry have lost twice as many workdays as a result of occupational illness as opposed to workers from other manufacturing industries.
All the efforts exerted by the semiconductor industry to clear its name from the occupational risks it is linked to seem to be in vain as opponents continue to throw more and more criticism their way. Although many studies have been conducted by the semiconductor industry in order to better understand the relationship between the supposed health concerns that result from the manufacturing process and the environment of the manufacturing itself, the validity of these studies remain questionable to the critics of the industry.
Without a standardization of the manufacturing process and without standardized safety regulations and procedures in the semiconductor manufacturing industry, the critics will not be silenced. (Tenenbaum, 283) The industry will continue to face an onslaught of harangues from all sides, a series of lawsuits from workers claiming occupational illness, and integrity loss with customers hearing of these issues. It may well be that the health issues of working with semiconductors is one of the top challenges against the semiconductor industry.
The financial aspect of the improvement and progress of the development of semiconductors stands to lose the most from the health issues circulating around semiconductor manufacture. Also, the industry must take into consideration the fact that there may be a solid empirical foundation behind the critics’ arguments. At which case, there is also the concern of the risks the workers are being subjected to just to be able to further the science and technology of semiconductors.
Over-all, semiconductors are experiencing numerous challenges to their progress. The challenges do not only include those on the side of science and its application but also branch out to a health aspect for the workers which also strike at the economic aspect of semiconductor industry. Despite the challenges to semiconductors, however, progress remains constant and there is hope of reaching the resolution of the problems already foreseen today.
What is most important in the semiconductor industry is the fact that even today; there are already insights into the problems that will be met in the future. Thus plans are already made and steps are already taken today in order to be able to cope with the challenges that will be faced in the future. Semiconductors face numerous challenges which are gigantic in scope. However, the means are within reach as along as those involved in the industry do not waver with their stalwart belief in their capabilities to better improve semiconductors.