Advanced packaging stepper for 300mm wafer process
With development of advanced package technology, requirements for lithographic process become tighter than before. When dealing with 200mm or 300mm wafer, stepper shows better uniformity of CD and overlay. SSB500 stepper can be used in RDL and Bump process. This paper introduces features of SSB500 stepper, such as wide band exposure light source, large field size, flexible alignment strategy, direct focus measurement, and proposes absolute overlay error concept and measurement method based on golden wafer. It also provides test data for CDU, UDoF, overlay for single machine and matching, thick photo resist performance, which shows specification of the stepper meeting well with advanced package process.