The use of proper statistical techniques has played an important role in maintaining the competitive posture of the U.S. semiconductor manufacturing industry. This is a highly competitive industry where the costs of new manufacturing facilities can reach one billion dollars and each fraction of yield or throughput gained can mean millions in revenue.
An active partnership of statisticians, engineers, and managers is needed to minimize manufacturing costs, while maximizing process yields and throughput. At the Semiconductor Manufacturing Technology Consortium known as SEMATECH, this partnership has successfully focused on optimizing semiconductor tools and processes, and on making management decisions that are data driven and as accurate as possible. This article, based on the invited President's address delivered by W. J. Spencer at the 1994 annual ASA meeting held in Toronto, describes how statistics is used within SEMATECH.
First we will look at the overall semiconductor industry and the role SEMATECH plays.
2. SEMICONDUCTOR MANUFACTURING INDUSTRY
The electronics products and services industry is the largest employer in the United States, with over 2.2 million employees and a $257 billion share of the annual gross national product. This industry depends heavily on semiconductor manufacturing, which employs nearly a quarter of a million people and accounts for a $37 billion share of the U.S. economy. Clearly, semiconductor manufacturing is an important segment of our total economy.
Worldwide semiconductor manufacturing is an $85 billion industry. The United States is the major shareholder, with about 44% of the market. It is, however, a rapidly expanding and changing market, as trends over the last decade or more illustrate.
The compound annual growth rate (CAGR) for worldwide semiconductor sales over the last two decades is shown in the box in Figure 1. Actual sales points are shown through 1992, and sales projections based on 10% and 14% CAGR are indicated from 1993 to the end of the current decade. Despite the recent slow down, the annual rate of growth over the next decade is still expected to be in the neighborhood of 14%.
Although the United States currently has a 44% share of this vital and rapidly growing world market, the industry forecast back in 1988 was not nearly so optimistic. This forecast is shown in Figure 2.
Reaction to the steady loss of worldwide market share to Japanese manufacturers during the early 1980s led to the founding of SEMATECH.
Figure 3 describes how the U.S. government and industry collaborated to found (and fund) the consortium known as SEMATECH. Current funding is 180 million dollars per year, half from the government and half from the U.S. semiconductor manufacturers who are members. These member companies currently are: AMD, AT&T, DEC, HP, IBM, Intel, Motorola, NSC, Rockwell, and TI.
SEMATECH's mission was simply to "solve the technical challenges required to keep the U.S. number one in the global semiconductor industry." This translates to improving the processes and materials and equipment used to manufacture semiconductor chips.
Shortly after SEMATECH began operation, the declining U.S. market share of semiconductor sales leveled off and then reversed direction [ILLUSTRATION FOR FIGURE 4 OMITTED]. While many factors contributed to this U.S. improvement, it is generally accepted that SEMATECH played an important part.
Solving the technical problems associated with semiconductor chip manufacture is frequently a difficult challenge, however, due to the enormous degree of complexity involved.
4. THE COMPLEXITY OF SEMICONDUCTOR CHIP MANUFACTURING
Three decades ago, a chip contained only one transistor and the manufacturing process was relatively simple. It was also easy to test the chip for functionality and make up for processing …