Electron Beam Proximity Effect Correction on the MEBES eXara Mask Pattern Generator

Abstract

Electron beam (e-beam) proximity effect correction (PEC) has become a critical consideration with the reduction of feature sizes and the increasing use of optical proximity effect correction (OPC). PEC is accomplished on the 50kV MEBES eXara system with the embedded PEC (emPEC) technique, which is an automated version of GHOST. This method equalizes the background exposure by writing a fifth pass in the reverse tone of the four primary exposure passes. This compensates for the dose differences in the background due to backscattered electrons. The result is feature size control independent of the proximity and density of surrounding features, and independent of feature size. The method is simple and does not require additional computations for raster scan systems. A description of the method and its results for both coverage proximity effect correction (feature size deviation as a function of the surrounding exposure density) and CD linearity (deviation of different feature sizes) is presented.