Seletes 300-mm mission
08/01/1997
Selete`s 300-mm mission
Haruo Tsuchikawa, Selete, Yokohama City, Japan
This article* explains the charter of Semiconductor Leading Edge Technologies Inc. (Selete) and describes its current primary task: the evaluation of manufacturing equipment and materials for 300-mm wafers. The evaluation includes overall concepts, specific systems, current status, and future plans. In coordination with the J300 program for standards development, Selete will evaluate about 50 complete systems per year at its facility.
Selete was established as a joint venture of 10 device manufacturers (Fujitsu, Hitachi, Matsushita, Mitsubishi, NEC, Oki, Sanyo, Sharp, Sony, and Toshiba) in February, 1996. Selete has ?5 billion in capital resources, from equal investments by the founding companies. The planned business budget for five years is approximately ?35 billion. The Semiconductor Industry Research Institute Japan (SIRIJ) first developed and proposed the basic concept for Selete. It was subsequently established as a research institute at which the above device manufacturers would cooperate to improve key technologies for the semiconductor industry in Japan.
The main tasks assigned to Selete are
the evaluation of next-generation semiconductor equipment and materials, and
research into key leading-edge technologies for future semiconductor engineering.
Selete aims to reduce research and development costs, which have been increasing dramatically, thus minimizing risks and accelerating the development of technologies.
For the evaluation of equipment and materials (task 1), Selete has started a program that focuses on 300-mm wafers. The present state of the program is detailed below. Research into leading-edge technologies (task 2) has, so far, focused only on TCAD. For 1997 and subsequent years, Selete plans to begin research on subjects related to key technologies such as lithography. Selete is already in full cleanroom operation in space leased from Hitachi`s Production Engineering Research Laboratory (Totsuka, Yokohama City), construction having been completed in November 1996. The cleanroom is a Class 1 down-flow type, having an area of about 2200 m2.
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Figure 1. Selete`s relationship to device manufacturers and equipment/materials suppliers.
The 300-mm program
Traditionally, each device manufacturer gave strategic importance to the development of its own original processes, and related equipment and materials. Each manufacturer`s process development was considered as strategic in differentiating its device from those of other manufacturers. In most cases, device manufacturers developed equipment and materials in direct cooperation with individual suppliers or through their own manufacturing departments.
The increasing sophistication of equipment and materials technologies has, however, increased the cost of development without differentiating final devices. The rise in costs across the entire semiconductor industry can be attributed to delays in the standardization of equipment and materials. Investment in the equipment for a single production line far exceeds ?100 billion. It is thus extremely difficult for a single device manufacturer to take the lead in converting to large-diameter wafers in an age that requires huge investments in research and facilities. To cope with this situation, and with the recent trend toward 300-mm wafers, Selete has started the 300-mm program to accelerate the development of related equipment and materials (Fig. 1).
Selete`s first major role is to summarize, unify, and present the requirements to the equipment and material suppliers. Such requirements were conventionally submitted separately, from each one of the many individual process development departments of device manufacturers.
The second important role is to evaluate the equipment and materials developed by the suppliers. After evaluating the product based on the pre-established requirements, the results are fed back to the supplier to accelerate development. As a matter of course, each device manufacturer finally determines the employment of equipment and materials for production only after its own additional evaluation. Selection for production is based on an individual manufacturer`s product policies, device structures, and plant concepts. Selete simply focuses on accelerating development in the "pre-competitive" phase of each device manufacturer.
Evaluation activities are funded by the device manufacturers, who entrust research and development to Selete. The results of evaluation and related intellectual property rights are given to the device manufacturers. Selete controls and operates the cleanroom used for evaluation as well as the evaluation environment (including all analysis equipment required for evaluation), and bears the cost of all materials necessary for evaluation (including wafers). Engineers and operators sent from the stockholder companies perform evaluations, analyze data, and give improvement instructions to the equipment and material suppliers.
In principle, all equipment and materials to be evaluated are delivered by the suppliers without charge. They subsequently receive the results of equipment evaluation and improve the equipment as required. Selete presents the acceptance and target specifications for each process to the supplier.
The acceptance specification is used to check that the received equipment or material is worth evaluating. The acceptance criteria is reasonable, so that many suppliers can be approved for evaluation. Specifically, the acceptance specification includes the minimum basic performance that can be evaluated by the supplier (prior to shipment) as well as the cassette-to-cassette handling, safety specifications, communication specifications, and any restrictions imposed on the building.
The target specification basically requires that process equipment performances obtained for the 0.25-?m generation be maintained for the manufacturing of 300-mm wafers. This current target will, however, vary with the development phases for the relevant equipment, increases in performance required by the device manufacturers, and improvements in the evaluation capability of Selete. The expected period required for evaluation is about six months to one year. The schedule for evaluation and the items to be evaluated will be determined separately for each case.
For a typical evaluation, a patterned sample wafer is introduced to a line incorporating the equipment to be evaluated. In addition to structural evaluation for coverage, the etching shape and the electrical characteristics will also be evaluated at the process module level. Electrical test includes the measurement of the basic transistor characteristics, a damage check, and a reliability test. A system enabling 0.25-?m patterning was planned for establishment in 1997.
Why 300-mm wafers now?
Selete started the 300-mm program considering the following: DRAMs have advanced one generation every three years, corresponding to a fourfold increase in density every three years. In each successive generation, the pattern minimum dimension is reduced to 0.6-0.7? that in the previous generation, while the wafer area increased by 1.3?. The bit cost thereby decreased by 25-30% every year.
Easy reduction in the minimum dimension of device structures has reached a physical limit since achieving 0.5 ?m. As a huge investment in research and development is required for a breakthrough, the development of ever-finer structures seems to have slowed [1]. On the other hand, SEMATECH estimates that a cost reduction of about 20% is possible per unit area of a wafer [2]. To overcome the increased investment levels needed and the difficulty in developing smaller device structures, a shift to the larger-diameter 300-mm wafers is urgently required to improve profitability. Without this shift, the growth of the entire electronics industry will also slow down.
An additional benefit of shifting to large-diameter wafers is that more chips can occupy the periphery of a wafer. The extent of the increase is dependent upon the individual chip size. Another advantage is that chip production can be increased without increasing the number of operators and engineers in the wafer fabrication section of a plant.
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Figure 2. Selete`s roadmap.
Status and prospects
A 300-mm-wafer roadmap (Fig. 2) was prepared by Japan Working Group of Silicon Wafer Summit (currently called Japan 300-mm Semiconductor Technology Conference [J300], which consists of EIAJ, JEIDA, SEAJ, JSMN, and SIRIJ) in November, 1994 [3]. This roadmap shows that the mass-production of 300-mm wafers will start in late 1999 or early 2000. Since the roadmap was created before Selete was planned, Selete was effectively established to implement this roadmap on schedule.
A recent questionnaire sent to the Japanese device manufacturers investing in Selete indicates that they still have a long-range goal of developing 300-mm mass-production lines at the times specified on the roadmap, in spite of the recent recession in the semiconductor business. Selete is charged with the mission of establishing a technical environment that enables the mass-production of devices using 300-mm wafers by 2000. For this purpose, Selete performs equipment evaluation and pilot line tasks on behalf of the entrusting device manufacturers, thus reducing the time required for such tasks. Equipment and material suppliers are also expected to follow the development schedule with Selete.
The schedule for installing the equipment to be evaluated by Selete (Fig. 3) is still under negotiation with the equipment suppliers. Enough equipment suppliers were willing to participate in this program that about 35 systems were planned for installation in the first half of 1997. Selete will evaluate about 50 systems/year.
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Figure 3. Schedule for installation of the equipment to be evaluated, not including metrology tools.
International efforts
There are many activities related to the standardization and equipment evaluation for 300-mm wafer processing in Japan and the US (Fig. 4). In the US, the International 300-mm Initiative (I300I) has started equipment evaluation for 300-mm wafers, working as a subsidiary of SEMATECH. I300I is funded by 13 device manufacturers, including those in Asia and Europe, and the budget for the first period is said to be US$26 million for one and a half years. Its main objective is to accumulate data from single-unit evaluations performed by the equipment suppliers. Although its evaluation style differs from that of Selete, I300I is consulting with Selete to start a collaboration.
In Japan, J300 is promoting the standardization of technologies related to 300-mm wafers. In the US, I300I will collect and summarize the requirements of device manufacturers and input them to SEMI. J300 and I300I are consulting on the arrangements required to establish international standards. As Selete is basically in charge of the evaluation of equipment and materials, it will perform evaluations according to the results of standardization by J300.
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Figure 4. Cooperation among groups evaluating the move to 300-mm.
Conclusion
Both the device manufacturers and the related equipment and material suppliers have great expectations for Selete. Recognizing the importance of the mission entrusted to us, we must fulfill our duties to contribute to the development of the industry. We sincerely ask for your help and advice.
References
1. SIRIJ Report, March 1996.
2. SEMATECH: Materials of the 300 mm International Consortium proposal.
3. Japan Working Group of Silicon Wafer Summit: 2nd Silicon Wafer Summit Conference, November 28, 1994.
HARUO TSUCHIKAWA is general manager and director of Semiconductor Leading Edge Technologies, Inc. (Selete), Yokohama City, Japan. Since 1996, he has been leading Selete`s main project on equipment evaluation for 300-mm wafer manufacturing. Prior to his position with Selete, he held senior management positions at Fujitsu. He served as a program chairman of the Semi Technology Symposium in 1995/96. Selete, ph 81/45-866-6840, fax 81/45-866-6880, e-mail [email protected]
This article originally appeared in the proceedings of SEMICON Japan `96.