Patent ID: 6087668
Filing Date: 2000-07-11
Classification: B82Y,H01J

Abstract:
A charged-particle-beam (CPB) projection method, comprising the steps of:(a) emitting a charged-particle beam onto a mask defining a pattern to be projected onto a sensitive substrate, the pattern being divided into multiple mask subfields, each mask subfield containing one or more pattern segments having minimum-linewidth features;(b) projecting each of the mask subfields onto respective transfer subfields on the substrate using a CPB-optical system and deflectors; and(c) before exposing each mask subfield, setting the focal length of the CPB-optical system based on the location within the mask-subfield of the pattern segments having minimum-linewidth features, so as to minimize blur of the projected mask subfield image on the respective transfer subfield at the pattern segments having minimum-linewidth features.