SEMICON WEST REPORT: Rift grows over 450mm wafer plans

by Bob Haavind, Editorial Director, Solid State Technology

Sharp differences on the need to prepare for a shift to 450mm wafers broke into the open on SEMICON West’s opening day (Monday, July 16).

Speaking for toolmakers, Stan Myers, SEMI CEO, at a morning press briefing, stated that: “Huge benefits remain to be gained by improving 300mm productivity.” This effort is currently underway in the 300mm Prime program, spearheaded by International SEMATECH, a chipmakers’ consortium.

“Only after these gains,” Myers added, “does it make sense to go to a larger wafer size.”

He suggested that the timing for such a shift might be around 2020 or later, making it unnecessary for the industry to begin preparations now. Myers added that, since it appears that it will be increasingly difficult to meet performance targets with silicon as features continue to shrink, it might be necessary to consider some alternate wafer materials in the future. This is another reason to put off preparations for an eventual 450mm shift, he suggested. He also said that chipmakers with a diverse product mix, such as major foundries, might not benefit from a 450mm wafer transition.

A very different view of the need to prepare now for an eventual 450mm transition was presented by Scott Kramer, of International SEMATECH, at a briefing and workshop for some 100 industry representatives, including vendors, on Monday afternoon. Kramer, who directs the International SEMATECH Manufacturing Initiative (ISMI) that has been conducting the 300mm Prime effort, emphasized that it is part of a complementary forward-compatible approach that will transfer lessons learned in the 300mm Prime effort to a 450mm transition within the next few years.

Early work indicates that although 300mm Prime promises to cut processing cycle times by up to 40% (vital for fast-paced consumer product cycles), it offers little chance for needed cost reductions. In fact, without a 450mm wafer transition, the semiconductor industry faces a $150 billion productivity gap by 2013, with a 50% increase in cost/transistor, Kramer suggested.

He said that history indicates that to maintain the pace of Moore’s Law, a wafer size increase is required about every seven years, which would mean a shift at about 2013.

SEMATECH is now conducting fab studies and simulations to determine whether the 450mm transition could “move out to an intermediate timeframe,” or needs to be accelerated, according to Tom Abell, 450mm program manager and Intel assignee to SEMATECH.

Under the 300mm Prime effort, reduction targets of 30% in cost, and 50% in cycle time, were set in 2Q06, Abell explained, which tracks the ITRS projections. Working with a wide range of fabs, the ISMI analysis showed the potential for 40% cycle time reductions, but only 3% cost savings, which might be improved to 10% — still far short of the 30% target.

Unfortunately, process tools for 300mm were designed back in the mid-1990s, before the explosion of foundries, so they are aimed primarily at high-volume, low-mix chip production. Much of the 300mm Prime work, according to Abell, is to improve the performance for the low-volume, high-mix needs of big foundries.

Due to the shortcomings of 300mm Prime, ISMI is initiating a 450mm program, according to Kramer. In 2008, it will pursue availability of 450mm wafers (which may need to be 1mm thick due to sagging at the edges from gravity), 450mm factory guidelines and standards, and creation of a 450mm factory integration testbed.

One problem: the members of ISMI are all chipmakers, representing some 60% of global IC revenues (Samsung, NEC, Panasonic/Matsushita, Spansion, Micron, TSMC, HP, TI, AMD, IBM, Renesas, Intel, Infineon, Qimonda, and NXP), according to Kramer — but no toolmakers. Why then, Kramer was asked, should the toolmakers cooperate with the effort?

“ISMI members are their customers,” he replied.

Stay tuned. — B.H.


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