Thick film positive DUV photoresis for implant layer application

摘要

A thick positive chemical amplified DUV photoresist, Shipoey UV 25, is designed with high transparency (0.18AU) for implant layer application> comparing with traditional Novolak I-line implant layer resists high aspect ratio and fast photospeed of UV 25 is demonstrated. Lithographic results show that UV 25 has excellent coating capability up to 3 microns thick, with excellent photospeed and good overall lithographic performance for various features. Process optimizations of UV 25 for various features are investiated. The results indicate that the temperatures of softbake and post exposture-bake play very important roles in impooving the process windows. We have found that high softbak for better annealing and solvent removal is critical, and the best lithographic process is typically at PEB temperatures lower than the softbake temperature (at lest 20 deg C lower). The process with a high softbake temperature and a low PEB temperature significantly improved overall process window. In addition, PED stasbility with an optimal baking process is also studied.