Abstract:

As the complexity of semiconductor devices has advanced, the quality requirements for the UPW used in their manufacturing processes have become increasingly stringent. The parameters that ascertain the quality of UPW include Total Organic Carbon (TOC), number and size of Insoluble Suspended Particles (ISP), and Non-Volatile Residue (NVR). An increase in the levels of any of these parameters may indicate a failure within the UPW system (oxidization system for TOC, mechanical filters for ISP, ion exchange beds for NVR) and monitoring these parameters assists plant engineers in determining areas within the system that require maintenance or repair.

In spite of the availability of instrumentation used to monitor these parameters, current best practices for UPW plant maintenance often rely on flow volume based rinse and replacement schedules, pressure based monitors/checks, or elapsed usage time. For new components, plant engineers often must rely on manufacturer specifications for their general and individual product quality. For the advanced technology components used to control critical UPW parameters, this ‘blind faith’ approach could benefit from the use of advanced instrumentation to quantify component performance and system suitability.

Using of state of the art instrumentation; maintenance schedules and procedures can be modified to reduce rinse time and water usage, and extend installed lifetime. Using the Kanomax FMT Model 8000 Non-Volatile Residue Monitor, Kanomax FMT Model 1000 Scanning Threshold Particle Counter, and the GE Seivers Model 500RLe monitor; the respective NVR, ISP, and TOC are monitored and shown to vary widely during resin and component rinsing. Additionally, the performance of a membrane filter can be quantified by monitoring upstream and downstream particle concentrations at a known challenge level. Individual filter failure within a bank of parallel devices is shown to be detectable using these devices.