Effect of delay time on the performance of DUV resist for various pattern size and shape

Airborne amine control history for DUV lithography dates back to early 1990's. Environmentally stable resist coupled with air filter system was successfully adopted to cope with the issue. Today's trend toward extending KrF lithography lifetime further, however, demands a hard-to-achieve goal in CD control budget. Small CD change which was acceptable several years ago can no longer be tolerated in current critical technology node. We came to know that CD changes in a different manner for delay time depending on the amine concentration, pattern size, shape, and density. At very low amine concentration, delay time dependency is strongly governed by the chemical composition of the resist material. Relaxation of such dependency could be fulfilled by tuning resist bake condition.