What Are Some Principles To Ultrapure Water Quality Sustainability?
By Berny Zerfas
Modern semiconductor fabs depend on ultrapure water (UPW*) for their survival. Disruption of UPW delivery for either quantity or quality issues can impact millions of dollars of business. UPW treatment systems can remove or introduce particles and contamination to the wafer surface; particle concentration in UPW correlates to particles on the surface (1).
Although it is critical to design, build, and start-up a UPW system that meets requirements, this treatment system needs to be properly maintained to avoid business impacts over its years of service. Two of the three UPW systems at the GLOBALFOUNDRIES 300-millimeter (mm) semiconductor facility at East Fishkill, NY, have been in continuous operation for more than 15 years. These UPW systems continue to meet requirements for 22-nanometer (nm) manufacturing and beyond. One key to this longevity has been a history of diligent maintenance and sustainability practices.
Figure 1. Simplified/typical process flow chart for a semiconductor UPW system.
Overall UPW System Configuration
Figure 1 shows a typical UPW system that is essentially the configuration of two East Fishkill UPW skids. Deionized water (DI) make-up water is supplied from the central utility plant (CUP). This DI water supply maintains the water level in the UPW skid storage tank. After the storage tank, the water flows through the following steps:
- Primary pumps
- Ultraviolet (UV) light (185 nm)
- Heat exchangers
- Booster pumps
- Resin beds
- Filtration (ultrafilter [UF] or cartridge filter)
- Distribution system
Some percentage of the UPW is consumed by process equipment with the remainder returning back to the UPW skid storage tank.
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