Due to the rapid technological advances in the microelectronics industry, the requirements for ultrapure water (UPW) used in wafer processing have become more stringent. As the number of chips per wafer increases, the linewidths in the chip circuitry become narrower, with linewidths now in the single nanometer range. Therefore, monitoring and control of UPW is essential to the FAB and Foundry.

Two critical parameters that must be monitored in real time are resistivity and total organic carbon (TOC). Strict control of these parameters in UPW systems enables semiconductor manufacturers to improve product quality and maximize yield.