Modified mask methods for pattern accuracy enhancement in electron beam lithography

Abstract

In projection-type lithography, delineated resist patterns differ from original mask shapes. In this article, aperture modification methods are investigated to enhance the pattern accuracy of electron beam cell projection lithography. The modified aperture is easily fabricated by decreasing the mask thickness. Although electrons penetrate the mask, enough high scattering contrast can be obtained. In dot delineation, star-shape apertures make better square dots near the resolution limit. In line-and-space delineation, dividing the pattern into small patterns of lower resolution reduces the electron current. This decreases Coulomb effects. In addition, Monte Carlo simulation results also confirm these results. As a result, these methods are expected to be important in the application of projection-type charged particle lithography.