In contrast, normal urban air has particle counts in the range of 5,, particles per cu. Since a human typically sheds about 15, - 20, particles.
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The finger style clean room is really a series of rooms with the bays being the higher class of clean room that contain the production equipment faces, wafers in process and production personnel. Surrounding the bays are the chase areas that are generally considered less "clean" than the bays. Located in the service chases are the process chemical pipes, electrical power lines and storage areas for various clean room materials. This arrangement allows technicians to service the equipment from the back without entering the production bay.
In addition to dirt and particle controls, temperature, humidity and vibration must be precisely controlled in a clean room environment. Clean room facilities worldwide will soon exceed million square feet, nearly double the 54 million square feet that existed as recently as the end of The recent application of clean room technology has found its way into manufacturing in other fields such as aerospace, biotechnology, pharmaceuticals, medicine and food processing. The shell of the furnace is cooled by water.
Electrical and Microelectronic Engineering
Finished, uncut crystals - known as ingots - can range up to ten feet in length. Once grown, water-lubricated diamond saws cut off the ends of the crystal ingots which are then ground to a uniform diameter and sliced into wafers. The wafers are then washed with flammable solvents and corrosives, polished, cleaned and given a thin surface of silicon dioxide.
The finished wafers usually range from 6 to 12 inches in diameter and resemble music or software compact discs. While the wafer is being created, the masks used to make the circuits on it are produced in a parallel operation. A mask is a thin, chrome coated glass slide that contains the circuit pattern and is used to shield portions of the wafer during photolithography, acting like a photographic negative, or a stencil.
Because each mask contains only the pattern for a single layer of the circuit element, many masks and layers of patterns are needed to make a single integrated circuit. The wafer and the mask finally come together during chip fabrication. This process can be compared to that of developing a photograph. As in photography, a negative is used to project an image onto material coated with a special chemical solution.
This solution allows the material to "hold" onto the image. The image is then developed, and the material that appears is washed in several solutions to preserve the picture. In chip fabrication, the "negative" is a mask and the "image" projected is the circuit on the mask, the "material" coated with a "special chemical solution" is a wafer coated with photoresist -- a light sensitive-chemical.
To "develop" an image, the wafer is positioned behind the mask and exposed. The unexposed photoresist is then removed in a chemical wash. The photoresist that remains is hardened in an oven, and the oxide that originally coated the wafer is removed and the underlying surface etched by gases to form the basic path of the circuit. Finally, various impurities known as dopants are infused into the circuit to give it the necessary polarity, resistivety and other desired characteristics.
These steps are repeated up to dozens of times as each layer of circuitry is built one upon the other like floors in a high rise building. When layering is finished, the circuit is completed with a coating of metal, usually aluminum. It generally takes from 8 to 20 weeks for an integrated circuit to be completed. Once the wafer fabrication is completed, the wafer is cleaned and ready for testing. Each of the chips on the wafer from a few to 1, on a single wafer depending on the chip and the wafer size is tested by a computer.
Handbook of Quality Integrated Circuit Manufacturing by Robert Zorich | Waterstones
Chips failing the test may be repaired using a laser repair system, depending on chip design. Defective chips are marked, and the wafer is then sawed with a diamond saw into individual chips. The good chips are sorted out and bonded into packages, or chip carriers. Circuitry on the chip is connected to the leads on the carrier by a computerized machine using gold wires thinner than a human hair.
Integrated circuit quality and reliability
The package is then encapsulated in an epoxy material for protection and tested again. Chips passing the final quality control are packaged for shipment. The first key consideration is increased property damage valuations on manufacturing risks. For property damage, it was mentioned earlier that product demand has increased the price of semiconductors over the past several years.
This has resulted in higher valuations, not only on the raw materials and work-in-progress goods, but also on the finished goods inventories. This has become a critical underwriting consideration because high values can be exposed to damage at numerous points in the production process. As an example, it is currently not uncommon for large chip manufacturers to have millions of dollars exposed in their clean room operations.
In addition, manufacturers have expanded facilities or built new ones, resulting in higher valuations on real and personal property, particularly the machinery and equipment where use of specialized robotics in the production process has increased. The underwriter must closely evaluate the potential causes of loss that can cripple the manufacturer. The perils of fire, smoke, water damage and contamination are the key direct damage issues to consider. The semiconductor manufacturing industry utilizes several types of specialized equipment; all of which are highly sensitive and can cost millions of dollars.
Some examples of this equipment include:. Additional materials that are present and potentially highly destructive are the various chemicals used in the manufacturing process, including:. These types of materials can offer a significant potential fire exposure and additional loss potential from water and smoke damage common to semiconductor manufacturers. These ignition sources and toxic materials combined with a concentration of sensitive and high-valued stock and equipment requiring a clean room environment lend this class to substantial property loss potential.
A malfunction, breakdown or failure of the proper use of materials and equipment in these various manufacturing processes can cause a significant business loss. The management and maintenance of equipment, wiring, chemicals and fire suppression systems are of paramount importance for the semiconductor manufacturer. The second key consideration involves the impact of time element losses on semiconductor manufacturing risks. Given the growing demand for chips, a manufacturer that suffers a loss, however small, faces the possibility of loss of sales and market share if it cannot resume operations very quickly since consumers will turn to an alternate source for the chips.
If a manufacturer has specialized processes or has a single production line, this concern is further increased. Another issue involves upstream and downstream contingent business interruption exposure. As chip manufacturers have become more concentrated in particular geographic locations such as Taiwan and California, the effect of an occurrence event in these areas can not only affect the risks located there but also affect other industries that are consumers of chips.
Chip manufacturers can be affected by losses occurring at various component manufacturers. Another consideration must be the waiting time required to obtain replacement machinery or parts for critical equipment. Customer supply and contractual demands can often result in significant extra expense and business income loss potential. Due to the rapid growth, continuing innovation and international dispersion of production plants, non-standard or "manuscript" property insurance contracts generally are used to insure semiconductor manufacturing plants.
These contracts are negotiated and specifically crafted to meet the needs of each individual insured. In this environment, the needs of each individual customer, the skill of the underwriter and the willingness of the insurer to undertake desired limits all determine the valuation approach. Most likely, due to the high values involved and the evolving nature of the technology, building and equipment values must be agreed upon.
In addition, both finished product and stock in process may be valued at selling price, a unique approach employed for semiconductor manufacturers. Highly valued properties and rapidly developing technology require that property values be established as accurately as possible, utilizing engineering and inspection services. Failure to establish proper valuation creates a greater potential for constructive total loss. All of these exposures make the use of providing blanket limits more difficult in this type of manufacturing process.
Special consideration and underwriting attention should be exercised when asked to consider blanket limits. If coverage applies this way, virtually all property can be included for coverage, depending on how insured locations are defined and on ownership requirements of the property. If "POED" describes the covered property, there must be an accurate and complete description of the existing property. Annual updates of this property should be obtained, so that insurance to value limits are established and maintained.
If stock in process is valued at selling price, this will have a direct impact on the business income exposure. The business income that this stock in process will generate, if completed and sold, is included in the selling price.
It is also important that the terms and conditions of the manuscript policy be clearly understood. Due to the unique nature of these contracts, previous understanding of terms will not apply. Today, even a relatively small physical damage claim may result in very large business interruption loss. If one or more of the following characteristics are uncovered during the risk analysis of a given potential client, it could render a wafer fabrication facility an undesirable insurance exposure Employment of semiconductor processors is projected to decline 27 percent from to Although there is a strong demand for semiconductors in many products, automation at fabricating plants is expected to grow, meaning that plants will need fewer workers.
Because during the manufacturing process semiconductors are highly sensitive to impurities, it is more effective to use robots to do many of the simple tasks that processors once did. In addition, the increasing complexity of chips, combined with their reduced size, makes it difficult for people to work on them. The semiconductor manufacturing industry, where most processors work, is also expected to decline, leading to more job losses. Operating a plant in the United States is more expensive than operating one in another country where manufacturing costs are often lower.
This leads to companies sending the manufacturing of chips abroad, even though designing the chips will continue to take place in the United States. Competition for semiconductor processor jobs is expected to be tough because of the projected decline in employment. Employment opportunities are not available in all states because semiconductor plants are expensive to construct, due to the high-tech manufacturing process that semiconductors must undergo. Employment opportunities for semiconductor processors are therefore concentrated in states where there are existing semiconductor plants.
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Semiconductor Processor. Is This the Right Career for You? Work Environment. Work Schedules Most employees work full time. In particular, after roughly a decade in which further generations of DRAMs in essence scaled down the basic DRAM design of the mids to smaller dimensions, a period of vigorous innovation began in the late s during which three-dimensional memory cells were developed. In the case of DRAMs, the increase in chip size was about 30 percent less than that predicted on the basis of lithography improvement alone. With the historical pattern of design innovation in DRAMs we have just seen, K equals approximately 0.
That this is the historical rate of decline in DRAM price quality-adjusted over the period is not completely surprising, since we have in effect used the DRAM to calibrate our estimated impact of design ingenuity, parameter K. What is more reassuring is that the methodology used for calculating quality-adjusted prices over this period makes no use of the technical parameters and predictions embedded in Equation 2 yet gives us completely consistent and congruent descriptions of trends in costs and prices.
It does not use any information on price per bit or any other direct calculation of price per electronic element or function. Interestingly, though not a perfect correlation, the Fisher ideal price index and a simple calculation of average price per aggregate bit shipped for all generations of chips produced at any moment are a close match over time. See Flamm, Mismanaged Trade , pp. One possible explanation is that Equation 2 captures some notion of long-run average cost, and that a lot of other factors—fluctuations in demand, entry by new competitors, exit by others, the impacts of trade and industrial policy—have shorter-term impacts on market price quite separate from long-term cost fundamentals.
This is certainly true, but an additional explanation is that processing cost per silicon area was not really constant over this early, data-deficient period—that it was instead declining in a way not captured in the above calculations. Thus, it can be argued that the early s were a period in which Japanese equipment manufacturers and IC producers were significantly improving semiconductor manufacturing technology, building in part on the technical successes of the VLSI Projects.
Indeed, U. See Flamm, Mismanaged Trade , chapter 2; J. Even in the early years, there had been a growing emphasis on projects designed to improve the equipment and materials used by U. Spencer and P. Grindley, D. Mowery, and B. Browning and J. It is far from clear that this acceleration of technological improvement in the semiconductor industry was solely the result of decisions taken within the membership of the U. Korean producers had become major players on the world semiconductor scene, and Taiwanese manufacturers were rapidly becoming a significant force.
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Accelerating competitive pressures were certainly being felt by U. Other institutional changes coincided with this industry-wide shift toward a two-year technology node pace. In a decision was made by SEMATECH to partner with foreign companies in a project aimed at accelerating the development of technology designed for use with mm in. In fiscal U. The existence of the National Cooperative Research Act of , which granted partial antitrust exemption to registered U. Shetler and Brown, op.
ATIP Let us now consider the economic impact of the move from a three-year cycle to a two-year cycle in the introduction of a new technology node. With the historical dose of ingenuity a la DRAM continuing i. These are impressively large numbers. Incredibly, even with the most generous assumptions about technological acceleration and further ingenuity in design and manufacturing, they fall short of the actual historical record for quality-adjusted DRAM and microprocessor prices in the late s, which fell at rates exceeding 60 percent per year! See Table 2. This acceleration in the decline of semiconductor prices has been noted by economists and credited with playing a significant role in the macroeconomic productivity growth acceleration of the late s, as well as an important role in more rapidly declining prices for the underlying computer and communications capabilities which fueled the technology contribution to resurgent productivity.
Figure 2 shows one set of measurements of quality-adjusted price change in DRAMs and microprocessors over this period. But this analysis suggests that while some of the more rapid technological advance and more rapidly declining prices in semiconductors are attributable to identifiable long-term changes in the pace of technical innovation in semiconductors, a substantial portion of the more rapid decline in semiconductor prices in the late s must be due to more transitory changes.
Likely candidates include cyclical fluctuations in product demand, intensified competition which may well end in some consolidation within this global industry as the least successful exit the industry , a shift of manufacturing processes for some products closer to the leading edge in technology, and a shortening of product lives accompanying more frequent introductions of new versions of certain products.
Leading-edge semiconductors may well drop in price at much faster rates than in the past as the result of faster introduction of new technology nodes over the long term, but the increase will be from 30 percent annually to a number in the 40 percent-plus range, not in a range exceeding 60 percent annual declines.
One would also expect productivity improvement flowing directly and indirectly from the sharp price declines for information technology of the late s to fall to more moderate—but sustainable—levels in future years. This certainly seems to have been the case in DRAMs, the pacing product for new semiconductor manufacturing technology, where a three-year next generation product introduction schedule became an accepted characteristic of the market. Then, in the s, as the U. Rather than simply accepting a historical norm, a decision was made to alter the norm by trying to explicitly coordinate the now-complex array of decentralized pieces of technology that had to be simultaneously improved in order to bring a new generation of manufacturing systems online.
Silicon Semiconductor Manufacturing
It may be impossible to determine the extent to which the coordination process played a role, or the extent to which the simple act of a major group of IC producers announcing new and very specific technology targets created a credible reason for the various suppliers of technology to believe that the technology cycle really was about to accelerate, and therefore caused it to accelerate.
The executive agents for this organizing framework were originally national in character. The U. But reality—that U. Today, the roadmap process is thoroughly global in character. Economists are largely accustomed to thinking of the speed of technological change as something that is exogenous, dropping in gracefully from outside their models.
Ultimately, one moral of this story is that the pace of technological change in the semiconductor industry may have an endogenous component as important as its exogenous scientific foundations. Particularly where many complex items of technology secured from a broad variety of sources must be coordinated in a fairly precise manner in order to create economically viable new technological alternatives, vague and diffuse factors like expectations and even political coalitions may play an important role. This paper has constructed a simple framework for explaining how technological trends in the semiconductor industry are ultimately reflected in the dy-.
The framework does a reasonable job of tracking real-world, quality-adjusted price trends for leading-edge products over the period. Moreover, the same framework suggests that an acceleration in the introduction of new technology nodes in the late s had a significant and predictable impact in further increasing the rate of decline in leading edge chip prices that took place at that time. These calculations, however, indicate that the actual fall in these prices over this period substantially exceeded the decline attributable to sustainable, long-term cost trends, suggesting that the extraordinary price declines of the late s—in excess of 60 percent for memory chips and microprocessors—were transitory in nature.
Even with optimistic assumptions about further innovation, I conclude that price declines must moderate significantly from these stratospheric rates over the long haul. To the extent that macroeconomic productivity growth and robust sales of information technology over this period were based on these component cost foundations, they too must fall back to more moderate rates in the future. Here we must also end on a note of caution. What the roadmap gives, the roadmap can also take away.
Recent roadmaps, while continuing to call for two-year technology nodes in the near term, have perhaps wistfully or nostalgically also called for a return to an older, slower pace of technological change toward the end of this decade.
Recent roadmaps have also suggested slowing down the pace of new-product introductions in DRAMs in the future, calling for a quadrupling of memory bits on a chip every four years instead of the historical three-year interval. While these choices may be dictated by technical issues, the roadmaps provide a framework in which economic implications can be discussed when technical choices are set cooperatively. The current roadmap process seems to be open and transparent. But because the roadmap framework for guiding technological change in this thoroughly global industry is international, the role of national governments in drawing the fine line between acceptable cooperation and unacceptable collusion may at some point need to be revisited.