USE OF POSITIVE AND NEGATIVE CHEMICALLY AMPLIFIED RESISTS IN ELECTRON-BEAM DIRECT-WRITE LITHOGRAPHY

This article describes the performance of available deep-ultraviolet ( UV) resists for electron-beam direct-write lithography applications, S hipley XP9402, JSR KRF-K2G, acid JSR KRF-L7 positive resists were eval uated for dark-field layers and Shipley XP90166 negative resist for cl ear-field layers. We investigate in detail the resolution capability, sensitivity, exposure latitudes and proximity, and postexposure delay (FED) time stability for isolated and dense features, as well as for c ontact holes. The influence of baking conditions on resolution and sta bility will be described. FED time effect in air and vacuum is measure d for features with dimensions down to 0.2 mu m. No linewidth variatio ns are observed down to 200 nm feature size with XP9402 for a delay ti me of 1 h in air if the postexposure bake (PEB) is done at low pressur e in He ambience. Feature sizes down to 0.25 mu m are kept within +/- 10% of the coded size, for a FED in air of 90 min if the FEB is done u sing a conventional hot plate in air. A process for printing 0.2 mu m contact holes is established. Resolution down to 0.15 mu m for dense, 0.12 mu m for isolated features, and 0.2 mu m for contact holes is obt ained with KRF-K2G for FED of 11/2 h in air using a top coating. FED s tability of more than 2 h and resolution down to 0.2 mu m for contact holes is obtained with KRF-L7 without applying a top coating. For clea r-field layers we focus on a negative tone process. Resolution and pro cess latitude issues using reduced resist thickness will be described. With 560-nm-thick XP90166. resist lines smaller than 0.2 mu m are res olved over polytopography with better than 25% exposure latitude. Furt her reducing the resist thickness to 500 nm, poly-Si gates with size d own to 0.15 mu m are defined on the shift register of a 0.25 mu m rand om logic complementary metal-oxide-semiconductor design. (C) 1995 Amer ican Vacuum Society.