Proximity correction on the AEBLE‐150

In this paper we describe a method for performing proximity correction of very large scale integrated circuit layout data that is applicable for use on the AEBLE‐150 electron‐beam lithography system in particular, and other dose modulated systems in general. The algorithm employed saves computation time and program space by retaining, insofar as possible, the pattern hierarchy. The problem of instances of a cell which are in different environments is addressed by high‐speed environment estimation through construction of equivalence classes. The dose computation algorithm requires edges to develop at designed locations, rather than requiring constant average exposure as in the so‐called ‘‘self‐consistent’’ approach. Certain heuristics are employed to accelerate the computation. Dose contributions of rectangular areas are computed via look‐up tables and simple arithmetic. A table look‐up approach is also applied for trapezoidal areas. The proximity correction computation is based on a multiple Gaussian equivalent scattering function. We will describe measurement techniques we have employed for extracting model parameters for use in the correction program. The performance of the program will be evaluated based on estimates of the various computational components.