PROXIMITY EFFECT CORRECTION DATA-PROCESSING SYSTEM FOR ELECTRON-BEAM LITHOGRAPHY

A proximity effect correction system has been developed by utilizing an efficient dose modulation technique based on a double Gaussian proximity function. A shaped electron beam system is assumed to be used. Two improvements are made. First, an optimal exposure dose on each pattern is determined by a new fast iterative method. The optimal dose makes the development isocontour conform to the pattern specification fairly well. Second, a "simple cell unit algorithm" that one of identical cells is proximity-corrected, and the result is used to the other remaining cells is introduced. This offers to both decrease the processing time and save the memory/disk space. The present system is applied to the data processing of scaled-down version of an aluminum wiring layer pattern of 16 Mbit dynamic random access memory with its minimum dimension of 0.4-mu-m. The calculation is successfully completed within 1 h of CPU time on a 10 MIPS general-purpose computer. The dimensional accuracy of 10% is confirmed experimentally for the pattern including minimum features of 0.4-mu-m in the combination of trilayer resist process.