Silicon Valley Awash in Water Shortage Fears : Drought: Computer chip manufacturers have changed their production processes to save the precious liquid. They fear added cutbacks could harm the quality of their product.
In the parched Santa Clara Valley, also known as Silicon Valley, millions of gallons of water a day wash across the surface of half-made computer chips, removing acids and impurities that can render the devices useless.
Like residents and other businesses in drought-plagued Northern California, computer chip manufacturers have pursued water conservation in earnest for years, and in many cases they have reduced their enormous consumption 25% to 30%. But water authorities are preparing a new round of supply cuts, and chip makers say there is little more they can do.
Local government and industry officials are optimistic that even the latest reductions--which are expected to mandate at least a 35% cut from 1987 water usage levels--will not force production cuts and layoffs at companies that form the heart of the region’s economy.
Still, if the drought continues, chip firms will eventually face a choice: Make major changes in a highly complex, water-hungry manufacturing process or move at least some of their operations to a wetter climate.
“The key question is what impact this will have on expansion and plant location decisions in the years ahead,” said Gary Burke, president of the Santa Clara County Manufacturers Group. “A predictable and adequate supply of water is essential for electronics manufacturing. Planners are now looking at this and saying, ‘I may not have an adequate supply.’ ”
Although company officials say the water crisis alone is not yet the decisive factor in plant location decisions, it stands with the high cost of land and housing, expensive electricity and stricter environmental laws as a major deterrent to new industrial development in Silicon Valley.
“This is a political issue,” said J. Rodgers, president of Cypress Semiconductor in San Jose. “We need assurances that our water supply will never be in jeopardy. If we cannot get those assurances, expansion in this valley is dead.”
A look at the intricate semiconductor manufacturing process makes it obvious why the water issue is so critical. Nearly all the dozens of steps require water, and poorly planned efforts to cut its use can drastically increase the number of faulty chips--with devastating effects on a company’s competitiveness.
The chip-making process begins with a slice of pure silicon, perhaps 6 inches or 8 inches across, which is then coated with a layer of silicon dioxide and a light-sensitive chemical called photoresist. A mask containing the circuit pattern is then placed over the wafer, and when light is shined through the mask, the exposed parts of the photoresist soften.
The wafer is then immersed in an acid bath that etches away the exposed photoresist and the silicon dioxide under it, leaving the hard photoresist in place. It is then rinsed with specially purified water and placed in a furnace, where heated gases diffuse into the exposed areas of silicon, forming the circuits by imbuing the silicon with certain electrical characteristics.
The wafer is again immersed in acid to remove the remaining photoresist and silicon dioxide, and rinsed again. The process is repeated 20 or 25 times to create additional layers of circuits.
All this takes place in a “clean room,” where the air is specially treated and all workers wear face masks and jumpsuits, because even the slightest impurity can render a chip useless.
In this hyper-clean environment, it’s not surprising that production engineers have tended to err on the side of excess when it comes to rinse water, even to the point of maintaining a continuous flow of water in rinse sinks that were not in continuous use.
Thus, the key economies chip makers began to implement several years ago involved fine-tuning their rinse processes. They moved to dump rinsing, which flushes water across a tray of chips only when a load is ready to be rinsed, and also to spin rinsers, which drip just a minute amount of water over a rapidly spinning wafer.
Substantial savings can also be achieved by using water more than once. Rinse water must be treated after use to remove the acids, and this treated effluent can be used for irrigation, for the air-conditioning system or for air-pollution-control “scrubbers.” Re-use also cuts the amount of water discharged to the sewage system.
The massive air-conditioning systems needed for clean room operations are also big water users. Recirculated air-conditioning water can be treated through ozonation, which eliminates the need to flush out water storage towers every few weeks and to change the cooling water.
At National Semiconductor, which does more manufacturing in Silicon Valley than any other chip company, these kinds of changes have cut water consumption 33% during the past three years, according to Bruce Gray, director of production and services at the company’s Santa Clara facilities.
Its fabrication facilities there use only dump-rinsers and spin-rinsers--rather than continuous flow sinks. And the number of rinses after each step has also been reduced. National now uses about 1.5 million gallons of water a day, 80% of it in the manufacturing process.
Other chip companies report similar successes, mostly with the same conservation techniques. At Cypress Semiconductor, water consumption has remained constant for the past seven years, even though production rates have increased 20-fold during that period, according to Rodgers.
Thus far, however, the conservation measures have been relatively inexpensive--in the hundreds of thousands of dollars. And in some cases, they even pay for themselves in reduced water bills, reduced costs for purifying the water and reduced sewage discharge fees. The next stage will be much more difficult.
“Until now, we’ve been getting the low-hanging fruit,” said Frank Giordano, head of general site services at Intel Corp. “To get to 35% (reduction), it might cost a million. Beyond 40%, we’d be spending big dollars and imposing great risks on the manufacturing process.”
Indeed, the question is not whether more water savings can be achieved but whether they can be achieved in an acceptable manner. For example, the acid-bath and rinse sequence can in some cases by replaced with dry etching, which uses a plasma gas rather than acid to remove photoresist layers.
This cuts down on acid use, Gray of National Semiconductor explained, which is in itself desirable, and also saves water. But many considerations must go into this type of process change, and water use is just one. In the highly competitive chip business, no company will undertake such a change if it decreases quality or productivity.
Far more extensive re-use of water is also possible, but that would require wholesale rebuilding of plumbing infrastructures at many older plants, an expensive task that could also disrupt ongoing operations. It might also require far more sophisticated--and expensive--water-treatment facilities.
Company officials hope that local water authorities will appreciate their conservation efforts and spare them the worst in any new cutbacks. Local officials are understandably reluctant to force reductions that would require production shutdowns.
Some larger chip makers, notably Advanced Micro Devices and National Semiconductor, have additional breathing room because they have closed older facilities in recent years and don’t need additional water-use authorizations. Intel, for its part, makes most of its chips outside the state.
But with the drought worsening daily, that could change. The Santa Clara Valley Water District, which serves Silicon Valley, draws its water from the State Water Project, the federal Central Valley Project and the San Francisco Water Department’s Hetch-Hetchy aqueduct. The district expects to receive 10% to 30% of the water it normally gets from those sources.
That means that even if the local ground water supply is overdrawn and if some water can be purchased from agricultural users in Yuba County, the supply could still be down as much as 50% from the 1987 level. Although local officials and water users have anticipate a 35% reduction in consumption, the water district may in the next several weeks mandate a bigger cut.
“My feeling is this new hit is going to hurt,” said Michelle Yesney, director of environmental management for the city of San Jose. “Everyone’s trying to find other options than putting people out of business, but there aren’t many options.”
