In previous years PYRAMID, a hierarchical, pattern shape modification scheme for proximity effect correction in electron-beam lithography, was presented. PYRAMID has been successful in correcting circuit patterns with a minimum feature size of 0.1 mum exposed in 200 nm poly(methylmethacrylate) (PMMA) on silicon. Current research has focused on improving PYRAMID so that it can handle thicker resists (e.g., 500 nm), which have a much greater proximity effect than do thinner resists. As a result, some of the assumptions and approximations that were made in the previous version of PYRAMID are no longer valid. Several modifications and improvements have been implemented in an effort to allow PYRAMID to correct circuits in thicker resists. The principle modification was the implementation of a new, table-based convolution method (termed CDF convolution), Using this method, it is possible to calculate exact local exposure values due to circuit elements located within the local correction window (3.6 mumX3.6 mum) during the correction. Other improvements include modifications to the junction correction and inner maximal rectangle adjustment phases of PYRAMID, as well as the addition of an option to iterate the correction. This article discusses these modifications and improvements and presents preliminary experimental results indicating successful correction of circuits exposed in 500 nm PMMA on silicon.