Purification of Trace Amount of Metal Impurity from Ultra Pure Water Using Membrane Purifier/Filter

摘要

Manufacturing processes for microelectronics devices, and silicon wafers get exposed to high-purity water more frequently than any other chemicals. The ultra pure water (UPW) produced at the central water system in a fab is of extremely high purity, with each critical metal concentration typically below 1 parts per trillion (ppt). However, it is difficult to maintain such high purity out of the central system during distribution to points of use for wafer cleaning. In the FEOL and BEOL wet cleaning processes, UPW wafer rinsing tools are designed to process many wafers in short period of time in order to reduce cost of ownership. The processes require high flow rate of UPW and need to be fed with the highest purity level all the time. We have reported the effectiveness of metal purifier/filter cartridge assembled from ion exchange membrane prepared from radiation induced graft polymerization method.[1] The advantage of using the membrane purifier device at point of use was also reported.[2] In this paper, consideration the practical conditions such as multiple metal contamination and colloidal impurity in UPW, the effect on the performance, and impact on microelectronics devices manufacturing are discussed.