ISMI 450 mm Program Moving to Next Stage

Several hundred manufacturing experts gathered this week for the annual ISMI Symposium, organized by the International Sematech Manufacturing Initiative (ISMI, Austin). Jefferson, an Intel assignee to ISMI, told symposium participants that the 450 mm program is evolving to development of "the initial toolsets," including a wet wafer cleaning tool from Solid State Equipment Corp. (SSEC, Horsham, Pa.) that will be moved into the cleanroom in Austin next Wednesday. The SSEC tool will sit alongside existing NanoPhotonics GmbH (Mainz, Germany) particle-detection and edge-inspection metrology tools installed earlier this year.

In the next phase, ISMI will send out 450 mm single-crystal, mechanical-grade silicon test wafers in newly designed shipping carriers, called HMACs, which are designed to the same size specifications and handling techniques used for the 25-wafer FOUPs. "We will loan test wafers to metrology and equipment vendors," Jefferson said. "The way it might work is for one company to do a blanket film deposition, and then send the test wafer on to a metrology company. To do that, we are developing a better supply of test wafers."

Over the past few years, the 450 mm program has defined and developed the initial 450 mm wafer carriers, with a 12 mm pitch. ISMI has worked with SEMI to define the 450 mm wafer thickness of 925 mm, with an edge exclusion of 1.5 mm, a wafer positioning notch, and other specifications that are set to be voted on as part of the SEMI standards-setting process, perhaps by the end of this year. Using polysilicon test wafers, the ISMI Interoperability Test Bed (ITB) in Austin has developed 450 mm load ports and EFEMs, and robotics have been developed and tested over ~5 million cycles.

Jefferson read out a list of ~20 companies that have participated in the ITB, saying, "We could not have accomplished what we have without their full participation." He added, "The work at the ITB is almost done. It will sunset."

In parallel with the development work performed at the ITB, the ISMI program has prepared the way for the next phase, meeting with ~30 equipment suppliers at a series of workshops this year to create equipment performance metrics (EPMs) for 60 different tool types. The EPMs have been posted to the ISMI website.

Jefferson said the 450 mm program is developing a common Demonstration Test Methodology for equipment. "How the equipment is tested is a work in progress. We will only test to the level of maturity of the tool, which means, for example, that we would not do a marathon test on a prototype tool," he said. "The level-one tools will be immature, but we still need to test."

The effort to encourage suppliers to develop CVD, etch, PVD and lithography tools, among others, has been going on at the EPM workshops and in private meetings. Jefferson said the three "IST" companies committed to 450 mm production — Intel, Samsung Electronics, and Taiwan Semiconductor Manufacturing Co. Ltd. (TSMC) — are planning to build their own 450 mm pilot lines by 2012, starting with 32 nm design rules. After that, it is up to each company to decide when and how to move forward with volume production, targeted at the 22 nm generation.

"We have three plus years to meet the next deadline, so I think we can be ready for pilot production with a whole tool set. Why not?"

During discussions this year, device makers made it clear that the 450 mm production lines would have to fit within existing fabs, allowing upgrades from 300 mm facilities. That means that fab cleanroom ceilings will have the same 12 ft height limitation, and the ratio between the production floor and the sub-floor will be maintained at 0.75.

The ISMI program has learned from the lessons of the 300 mm transition of a dozen years ago, according to analyst Dan Hutcheson, CEO of VLSI Research Inc. (Santa Clara, Calif.). "Far more planning has gone into 450, and they have been more transparent to the equipment industry," he said.

At the 2008 SEMICON West show, in particular, executives and SEMI staff expressed opposition to the wafer transition, arguing that the money and engineering resources would be better spent to improve the productivity of the 300 mm tools and fabs. Hutcheson said the public antagonism has subsided. "You don't hear the open negativity of a year ago."

Asked when he thought 450 mm volume production might begin, Hutcheson said earlier surveys by his company showed 2020-2025 as the likely introduction, well beyond the goal of the International Technology Roadmap for Semiconductors (ITRS) and the ITS companies. "Today, I think the industry is becoming a little more optimistic," he said. "When you look at the progress made by the ISMI program, 2020 might be a little far out."

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