Modification of mask blank to avoid charging effect

摘要

A blank mask for photomasking patterns on an integrated circuit comprises a non-conductive substrate and a layer of conductive material deposited on the substrate covering substantially the entire surface of said substrate. Methods for preventing charge accumulation on a non-conductive region of a mask, which is not covered by a layer of conductive material, are provided. One method comprises controlling electron beams to prevent the beams from striking an outer region for an area more than 90 percent of the outer region when patterning a predetermined feature on the mask. The outer region comprises an area beginning from an edge of the mask and ending at 2 to 6 mm inward from the edge. Another method comprises using a blocker to prevent electron beams from hitting the outer region for an area more than 90 percent of the outer region when patterning a predetermined feature on the substrate.