The Study of POU Filters Performance and Life-time in the CMP Slurry Supply System

Recently, the CeO2 (ceria) based slurry has been widely used in chemical mechanical polishing (CMP) process. Most of the CMP processes are using point of use (POU) filters in order to reduce unwanted micro-scratches. However, there is no clear evidence on filter's performance and life-time respect to various conditions, such as slurry type, filter retension size and various kinds of slurry supply conditions. Through this study, we observed the performance of the filters by measuring particle size distribution change before and after filtration in above conditions. we used silica and ceria slurry, and two different types of 0.2 micrometer filters (A and B filters). And slurry supply system used in this study is cycling configruation. After filteration, abrasive size measurement was done by scaning mobility particle sizer (SMPS). In silica slurry case, particles larger than 300 nm are filtered vigorously than smaller particles. However nano particles (< 100 nm) which should not be filtered out are also removed by surface interations between particles and filter media. In ceria slurry case, around 100 nm particles are removed, which is similar with silica slurry case. Keywords: POU filter, filter life-time, particle size distribution, slurry, filtration efficiency