Hironobu Taoka

A Fast Eliminating System of Narrow Electron-Beam Exposure-Figures for Improving Pattern Accuracy

We have developed a system for fast elimination of narrow electron-beam (EB) exposure-figures, which degrade pattern accuracy when using a variable shaped writing scheme. In order to reduce the processing time, a hierarchical and a distributed processing method have been developed. In addition, two kinds of narrow-figure elimination methods have been evaluated for further reduction of the processing time: a whole figure-merge method and a pinpoint figure-merge method. It was found that both methods must be selectively used because the best method strongly depends on the total amount of initial narrow figures in input data. The developed system has been applied to EB exposure data for 5× reticles of a 256 Mbit dynamic random access memory (DRAM). The pinpoint figure-merge method was used because its processing speed was 1.5 times higher than the other method for this case. The narrow-figure elimination has been completed successfully in a practical time; it was 2.8 hours for 4 critical layers of a 256 Mbit DRAM.