OPTIMIZATION OF A HIGH-PERFORMANCE CHEMICALLY AMPLIFIED POSITIVE RESIST FOR ELECTRON-BEAM LITHOGRAPHY

We report on sub-0.1 mu m electron-beam (EB) Lithography using a new c hemically amplified positive resist with a stabilizing additive. Diphe nylamine (DPA) was incorporated into the resist formulation as a stabi lizing additive. DPA improves the post-exposure delay (PED) stability. Even after a PED of 60 min in a clean-room atmosphere (NH3 concentrat ion similar to 20 ppb), no insoluble surface layer was observed for th e resist with DPA. High sensitivity and resolution could be achieved b y optimizing process conditions such as baking and developer. 0.1 mu m lines-and-spaces (L/S) patterns and 0.08 pm hole patterns were obtain ed using a 50 kV variably shaped beam EB system. The practical sensiti vity was 6 mu C/cm(2) for L/S patterns. Our resist system also shows g ood performance as an etching mask. A 0.1 mu m diameter hole which was 0.5 pm etched in silicon oxide using a 0.5 mu m thick resist could be obtained in this experiment.