UV Technology Breakthrough for Rinse Water Treatment

The company's scientists had researched wafer rinse water treatment using UV lamps since 1997. By experimenting with different types of quartz glass, chemical additives, lamp geometries and electrode designs, the researchers developed the SuperTOC lamp with a UV output optimized for electronics applications (Figure). The lamp can turn a high percentage of its energy input into a UV light at the wavelengths needed for treating electronics rinse water. Specifically, the lamp delivers >10% output compared with conventional lamps, which convert 0.2% of energy input into useful UV light output. Applications include RO membrane and ultra-filter protection; post-DI resin; pre-DI resin conditioning for organic removal; de-ozonation; post- storage tank disinfection; high-purity and ultra-pure water loop TOC reduction and microbial control; dechlorination to reduce low-level residual chlorine; and re-use and regeneration water. The high-powered SuperTOC lamps also can be used to improve performance in TOC reduction, disinfection and ozone removal applications.

Using CO₂ Fluid for Cleaner Chipmaking

On the average day of operations at a chip manufacturing plant, about 4 million gallons of wastewater is produced, and thousands of gallons of corrosive hazardous materials — like hydrochloric and sulfuric acid — are used. Scientists at the Department of Energy's Los Alamos National Laboratory (Los Alamos, N.M.) developed a new technology application that could eliminate the use of hazardous corrosives and the production of wastewater in the fabrication of integrated circuits. The technology, called SCORR, focuses on photoresist removal, where high-intensity light with aggressive acids and corrosives are used to create a chip's circuits by altering the topography of a silicon wafer. It uses carbon dioxide at high temperature and pressure in place of the hazardous materials.

This technology is designed as a closed-loop system that reuses the carbon dioxide in the process, adding no greenhouse gas to the atmosphere. The additive cosolvents are easily separated from the mixture — because of their low vapor pressure — and can be collected and reused. This photoresist removal technology produces virtually zero hazardous waste. A significant part in the process is a tiny high-pressure sprayer that pulses the SCCO₂/cosolvent onto the silicon wafer to assist in dislodging the photoresist. The sprayer creates enough surface drag to dislodge the microscopic bits of photoresist already softened from soaking in the SCCO₂/cosolvent mixture. This combined process of soaking and spraying, with an SCCO₂-only wash, produced results that equal the chip fabrication standards currently accepted in industry.

For additional information on clean processing, go to www.semiconductor.net/clean