Enhanced proximity-effect correction for VLSI patterns in electron-beam lithography

When applying a proximity-effect correction to VLSI patterning, the major challenge is to obtain a highly accurate pattern without excessive computation. A fast correction program that has two new techniques for the proximity effect has been developed for highly accurate VLSI patterning on a negative resist. The first technique is the effective definition of sample points where energy intensity is calculated to obtain a highly accurate pattern. The second is the use of the exposure-intensity reduction rate which corresponds to a change in the pattern dimensions to reduce the computation time. A pattern accuracy of ±0.1 µm and a uniform resist of the desired thickness were obtained. The computation time is proportional to the 1.2 power of pattern density.