Semicondutor Manufacturing Plants can use as much water as a small city.

As the Industry Grows, Finding New Ways to Recycle and Conserve Water

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This segment is part of the Engineers of the New Millennium: The Global Water Challenge Special Report.

Transcript: Mopping Up the Purest Water

Laurie Howell: You have to prepare yourself for a lot of noise in this engineering research center. Located in a warehouse on the University of Arizona campus, this mini computer-chip manufacturing plant is a test facility. This is where engineers can re-create all the industry's water issues, so they can fix them.

Ting Sun: So, here is a typical 200-millimeter polisher—looks like—at the bottom is the rotating pad.

Laurie Howell: Chemical engineer Dr. Ting Sun gives me a tour of the polishing room, lined with various sizes of flat, round silicon wafers.

Ting Sun: And when we're ready, we're gonna bring the head down and the wafer will touch the pad. All of them are rotating, so they're gonna do the polish work.

Laurie Howell: Polishers spin the silicon wafers against a pad and a chemical mix known as slurry, polishing each layer of circuitry and then rinsing it with ultrapure water.

Ting Sun: By doing that, we can use less chemicals, so we dump less chemical into the environment, so that helps a lot, and also by using less of chemical, we also use less water to rinse it.

Laurie Howell: A true 21st-century chemical engineer, Sun is educated in a practice called design for the environment.

Farhang Shadman: Design for environment basically means that those who are in charge of developing new processes will have the environmental, not only environmental thinking but also the tools and techniques of environmental assessment in their way of doing research.

Laurie Howell: Dr. Farhang Shadman has directed the center since its launch in 1996. Formally called the SRC/Sematech Engineering Research Center for Environmentally Benign Semiconductor Manufacturing, it has grown to include nine universities across the U.S.

Farhang Shadman: Probably the legacy of the center is showing and proving, by many, many examples, that environmental approach to technology not only makes sense, not only it reduces cost, it may be the only way that future manufacturing is done.

Laurie Howell: Computer chipmakers watch this center closely for new technologies, and it's easy to understand why. Many semiconductor manufacturing plants are located in the water-strapped cities of the Southwest.

Farhang Shadman: One manufacturing plant uses anywhere between 2 to 4 million gallons of very, very pure water—we call it ultrapure water—per day, and that, on the average, is roughly equivalent to the water usage of a city of maybe 40 000, 50 000 people.

Laurie Howell: Shadman guides me past a room with engineers dressed head to toe in what they call “clean-room suits,” which protect the research from outside impurities. Just like surgery, semiconductor manufacturing requires a sterile environment.

Farhang Shadman: Okay, what you see here is what we call a pilot plant, a water pilot plant, and it is very unique because it essentially resembles the water purification plants of semiconductor manufacturing, except that everything is in a smaller scale and everything is research development–oriented so we can change things, things that you can not do in the real manufacturing.

Laurie Howell: So, what we're looking at right here are different stations where the water goes through purification process, water softeners, carbon filters…and that's because the water that's needed in the semiconducting industry needs to be so pure, purer than any water, anywhere.

Farhang Shadman: Yes, because the wafer that is being cleaned is already very clean. You're trying to remove very, very small traces of impurity. So, if water has any contaminants in it…it will be harmful. Very interesting point is about bacteria: We cannot tolerate any bacteria—live or dead, it doesn't matter—because of the fact that the bacteria typically have some of the trace elements in them like phosphorus, like carbon. These traces of these compounds will change the electrical properties of the silicon wafer.

Laurie Howell: And that could lead to defective computer chips and, ultimately, product recalls. So, chemical engineer Dr. Jun Yan has been developing a new water sensor that detects immediately when a silicon wafer is clean, so rinsing can stop, saving millions of gallons of water a day.

Jun Yan: Environmental concern, environmental issue, and how mankind, civilization can survive depend on what can we do and how can we approach it, so I think it's very exciting, very important, meaningful work.

Laurie Howell: Idealistic? Maybe, and maybe a whole lot more. The water sensor developed by Yan and his colleagues is already on the market and was named 2009 Product of the Year by SEMI, a global association for microelectronics and other industries.

Farhang Shadman: We want to make sure that manufacturing, and particularly high-technology manufacturing, is maintained and retained, kept in the United States, and if you do not solve some of these environmental issues and some of these resource issues, we stand the risk of losing that manufacturing to other areas.

Laurie Howell: The center has now spun off five start-up companies. And its environmental technologies are being applied outside semiconductor manufacturing and electronics, in the medical and pharmaceutical industries, among others. For Spectrum Radio, I'm Laurie Howell.

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