Exposure method utilizing partial exposure stitch area

Abstract

An exposure method of sequential beam, contributing to the improvement of alignment accuracy at connecting portion at the end part of an exposure region, as well as pattern dimension accuracy is provided. The method comprises the steps of dividing an area to be exposed into a plurality of fields each being determined by the deflection width of the main deflector, dividing each field into a plurality of sub-fields each being determined by the deflection width of the sub-deflector, applying a sequential exposure process to each field by using a variable shaped electron beam, and applying a multiple exposure process to an area where adjacent fields overlap each other, wherein the multiple exposure process is conducted in the area in units of sub-field, the exposure dose at each of exposure unit is determined such that the total exposure dosage in the area subject to the multiple exposure process is set equal to an exposure dosage used when single exposure process is applied, the exposure dosage in the area subject to multiple exposure process is decreased in steps, in the direction perpendicular to the longitudinal direction of the boundary portion from the outer edge of the field towards the outside of the field, an exposure dosage in the area subject to the multiple exposure process is determined using the minimum exposure dosage available in the exposure apparatus as the lower limit.