Lance Frazer

Abstract

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Producing semiconductor chips is an environmentally costly business, requiring huge quantities of water as well as toxic and/or corrosive chemicals to remove photoreactive polymers, or ³photoresists,² from chip surfaces. Many of these chemicals are either suspected or known carcinogens that require extreme care in production, storage, and handling, and they have exposed the semiconductor industry to millions of dollars in lawsuits brought by workers whose health was compromised by exposure to these substances. But now, the industry may have found an unexpected ally in the form of supercritical carbon dioxide (CO2) . Researchers at Los Alamos National Laboratory are experimenting with the Supercritical CO2 Resist Remover, or SCORR. In its supercritical form, CO2 has useful properties of both liquids and gases: It has the density of a liquid, but a gaslike viscosity and lack of surface tension that enables it to get into and clean tiny spaces. The SCORR process uses pure CO2 for the final rinse step, saving millions of gallons of water. Furthermore, the process is environmentally benign and alleviates worker exposure to the corrosive, toxic, and highly flammable products used in current technologies.