Automatic dose optimization system for resist cross-sectional profile in aelectron beam lithography

A computer-aided dose optimization system to obtain a modified resist cross -sectional profile is demonstrated based on resist development simulation a nd an iteration procedure of the exposure dose profile for a positive elect ron beam resist. The absorbed energy in the resist by the electron beam exp osure is evaluated by conventional Monte-Carlo simulation and the resist cr oss-sectional profile after development is predicted by a cell removal mode l. The exposure dose profile is optimized by an iteration procedure based o n the predicted resist development profile. The exposure dosages at each po int are corrected based on the difference of the average absorbed energy de nsity between the desired developed surface and the predicted profile by th e resist development simulation. The system is applied for blaze pattern fa brication for diffractive optical elements and a fine blaze pattern is succ essfully obtained.