Semiconductors Now Require Ultra-Ultrapure Water

These excerpts are from a recent technical conference on ultrapure water for clean rooms.

In addition to the demineralizing and purification of supplied municipal water, it is important to maintain this purity prior to its use in the production of semiconductor components. Many facilities have final filters positioned just before the ultrapure water is used in the process. These points of use (POU) filters are important for preventing particles from getting into the system and causing "killer defects" on the microchips. This is done because operators believe that the water quality can degrade during transit and that POU filtration will provide assurance for the highest quality water possible.

Another view is that the POU filters and any other treatment which takes place in the clean room may contaminate the water. It is also felt that the high-purity water from the initial treatment plant will retain its quality attributes up to the work station. This assumes that the initial equipment is properly operated and the distribution system is designed to eliminate potential biofouling. It also assumes that no contamination will come from the piping and pumps which will be made of material such as virgin polyvinylidene fluoride (PVDF) or polypropylene (PP). These materials are frequently specified as "unfilled and unpigmented" and are required for the main distribution loops. There is interest in ECTFE (ethylene-chlorotrifluorethylene) as another option. The drawback to ECTFE is higher cost and the feeling that any benefits it may offer do not outweigh the greater expense. For many plant operations not requiring ultrapure water, satisfactory service is achieved with standard polypropylene (PP). This is particularly true in the handling of wastes or in other operations before the polishers.

Since ultrapure water is a costly product, semiconductor plants are exploring ways to make better use of available water supplies. One approach involves "cascading" the wastewater from the work stations for use in plant scrubbers or cooling towers. Because this wastewater becomes acidic from acid rinses at the wet bench stations, neutralization is required before its use in cooling towers.

Chip manufacturing, scrubbing and neutralizing processes all result in the use of Vanton thermoplastic pumps.

Here is a partial list of our world-wide customers:

ADVANCED CIRCUITS INC. ADVANCED CONCEPTS INC. ADVANCED MICRO DEVICES AKZO AMP APPLE ARI TECHNOLOGIES AT&T BELCO TECHNOLOGIES CFM TECHNOLOGIES DIGITAL FUJITSU HADCO HEWLETT PACKARD IBM INDUSTRIAL DESIGN CORP INTEL IONICS LUCENT TECHNOLOGIES MEMC METHODE ELECTRONICS MICROSOFT MITSUBISHI MOTOROLA PHOTOCIRCUITS SAMSUNG SEH AMERICA SEMATEC SGS THOMPSON SHIPLEY TECHTRONICS TEXAS INSTRUMENTS TOSHIBA