EDITOR'S PAGE

Not if, but when

The geologic and economic aftershocks from the tragic Taiwanese earthquake continue to rumble. News reports from the island indicate that the local semiconductor fabs suffered little structural damage and many have nearly reramped to full production levels. But estimates of costs suffered because of lost wafers and fab shutdowns reach the tens of millions of dollars for each day off-line. Although the facilities are coming back on-line sooner than expected, the ultimate yield impact of the devastating quake will not be known until the facilities run new silicon through the whole line on their recalibrated equipment sets.

Taiwan is not the only chipmaking locale susceptible to quake-induced shutdowns. Fabs located in the "Ring of Fire" earthquake zone around the rim of the Pacific Ocean account for hundreds of thousands of monthly wafer starts. South Korea, China, and Japan, as well as the U.S. Pacific Northwest, Idaho, and California all lie in quake zones. While most production-scale chipmaking has left the greater Silicon Valley area, the region still has one of the world's highest concentrations of semiconductor and microelectronics suppliers and end-users.

Two major faults split the earth nearby. The Hayward fault stretches down the East Bay, and the notorious San Andreas fault slices down the Peninsula on its way toward Central and Southern California. While geophysicists note the chance of a catastrophic earthquake (around 8.0 or more on the Richter scale) is quite low in the near future, the probability of one measuring 6.8 to 7.5 on the Hayward fault remains high. Steve Hickman of the U.S. Geological Survey says that a probability report issued by the agency posits a 2 in 3 chance of a 7.0 or stronger quake from the Hayward fault by 2020. So the question of a big one coming is not if, but when.

The USGS, university community, and local governments have been working together to improve ground-shaking models and other quake damage indices. Hickman notes that accurately predicting the effects of a large temblor remains an "art form," but great strides have been made. Potential damage models account for proximity to the epicenter, underlying geologic material including soil type, and the strength and duration of shaking. Those who saw the devastation in San Francisco's Marina district following the 1989 Loma Prieta quake can understand that seismic waves intensify in loose, sandy soil, making many structures susceptible to collapse.

Because the chipmaking community weathered the Loma Prieta shaker fairly well, some may believe that the necessary precautions are in place to ride out the next major seismic event. This assumption has a serious flaw: the 1989 temblor was centered well away from the valley, in an area south of Santa Cruz, while the southern part of the Hayward fault runs within a few miles of the East Bay and northern San Jose. Cities such as Milpitas and Fremont could suffer violent to very violent shaking and extensive damage from a large quake erupting on that end of the fault. A subsite on earthquakes on the Association of Bay Area Governments' Web site (http://www.abag.ca.gov/) contains a report titled "On Shaky Ground" with color-coded earthquake hazard maps for many such scenarios. Another good Internet site is the USGS's own Earthquake Information pages — http://quake.wr.usgs.gov/.

Rick Koski of SEMI/Sematech believes that "the biggest issue in the Silicon Valley would be disruption of the transportation infrastructure." He adds that as far as semiconductor-specific problems are concerned, "the first thing that comes to my mind is the very extensive gas delivery system pipelines that go through the area. If they were to be damaged or in any way destroyed, it wouldn't matter what happened at the individual fabs — they would be shut down for lack of chemicals." He notes that because of quake-resistant building practices and industry standards like SEMI's S2-91 statute, "there would probably be very little damage to fabs" and "equipment is built with that in mind."

Koski says that "we have a very good national infrastructure for disaster responses" and that most companies in the Bay Area have established quake preparedness plans. With the harrowing events from Taiwan fresh in our memories, it's time for the semiconductor community, in Silicon Valley and elsewhere in earthquake country, to reexamine their emergency contingency plans and learn some hard lessons from Mother Earth's recent paroxysm.

Tom Cheyney
Editor

tom.cheyney@cancom.com
http://www.micromagazine.com

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