Industry agrees on first 450-mm wafer standard

AUSTIN, Texas -- Hoping to accelerate the development of 450-mm fabs, International Sematech and others have formulated a preliminary standard for 450-mm silicon wafers.

But the 450-mm era could get delayed amid the IC downturn and current economic crisis.

Meanwhile, after several competing proposals, Sematech, SEMI and the IC industry have settled upon a wafer thickness standard of 925-micron, plus or minus 25-micron, for the so-called ''mechanical standard'' for 450-mm silicon wafers. The ''mechanical standard'' is an early and preliminary standard. In comparison, a 300-mm wafer has an overall thickness of 775-micron.

A standard is key for 450-mm wafers. This will enable the development of the initial wafer handling and other systems for 450-mm fabs, said Michael Goldstein, materials principal engineer at Intel Corp. (Santa Clara, Calif.), one of the driving forces behind the next-generation wafer size. Intel is one of the members of Sematech (Albany, N.Y.), which is driving the 450-mm movement.

Then, in November, the industry will take the next step. It will vote upon a ''test wafer thickness'' standard for 450-mm wafers, but 925-micron appears to be the target. ''We do not expect a big change'' from the 925-micron standard in the next proposal, he said.

Then, over time, the industry must decide upon the ''production wafer thickness'' for 450-mm substrates. That could happen in 2010 or 2011.

To jumpstart the 450-mm era, Sematech last year announced a plan to devise a "factory integration test bed" facility for the development of 450-mm fab tools.

The proposed facility would help enable chip-equipment makers to develop the initial fab-automation gear, such as carriers, load ports, modules and other items.

The proposed pitch specification for 450-mm tools is 10-mm. But this week, Sematech will demonstrate a pitch specification of 9.2-mm and a wafer deflective sag value of 0.353. In comparison, Sematech last year demonstrated a pitch specification of 9.4-mm and a wafer sag value of 0.613.

A 450-mm wafer weights 330 grams, which can cause the substrate to bend or sag on a wafer handling system. The key is to make the substrates and handling systems robust enough to offset the sagging effect.

Still to be seen, however, is when 450-mm fabs will appear. As reported, Intel, TSMC and Samsung are separately pushing for the advent of 450-mm ''prototype'' fabs by 2012 or so. Some believe 450-mm fabs will never happen, saying the R&D costs are too expensive.

If or when 450-mm appears, the first production fabs could emerge at the 8- or 5-nm nodes, somewhere between the 2017 to 2019 timeframe, said Dean Freeman, an analyst with Gartner Inc., at a recent event. And in total, it could cost a staggering $20-to-$40 billion to bring the next-generation wafer size to the market, Freeman said.