Patent ID: 6780574
Filing Date: 2004-08-24
Classification: G03F

Abstract:
A multiple-exposure method comprising the steps of:a first exposure step for exposing a substrate with a first pattern, by use of a projection optical system; a second exposure step for exposing the substrate with a second pattern, by use of the projection optical system, wherein the first exposure step uses a first mask having a first mask pattern including lines and spaces, while the second exposure step uses a second mask having a second mask pattern including lines and spaces; wherein a width of a line or a width of a space in a finest portion of the first mask pattern is made substantially equal to a width of a line or a width of a space in a finest portion of the second mask pattern, wherein the second mask pattern has a second portion in which a width of a line or a width of a space is larger than the width of the line or space in the finest portion of the second mask pattern, wherein in the first exposure step the finest portion of the first mask pattern is resolved, while in the second exposure step the finest pattern portion of the second mask pattern is not resolved but the second pattern portion of the second mask pattern is resolved, wherein a resultant pattern obtained on the basis of the finest portion of the first mask pattern and a resultant pattern obtained on the basis of the finest portion of the second mask pattern are superposed one upon another on the substrate, and wherein a numerical aperture NA2 of the projection optical system in the second exposure step is made smaller than a numerical aperture NA1 of the projection optical system in the first exposure step.