Patent ID: 6372395
Filing Date: 2002-04-16
Classification: G03F

Abstract:
An exposure method in which mask patterns are overlaid on one another on a photosensitive substrate, which is an object to be exposed, by using a first exposure apparatus having a first exposure field of a predetermined size on said photosensitive substrate, and a second exposure apparatus having a second exposure field which is M1/N1 times (M1 and N1 are integers; M1>N1) as large as said first exposure field in a first direction and which is M2/N2 times (M2 and N2 are integers; M2&gE;N2) as large as said first exposure field in a second direction which is perpendicular to said first direction, said exposure method comprising:a first step of sequentially transferring an image of a first mask pattern, which has an alignment mark and a first overlay accuracy measuring mark, onto said photosensitive substrate in the form of a two-dimensional array extending in said first and second directions in units of said first exposure field by using said first exposure apparatus; a second step of transferring an image of a second mask pattern, which has a second overlay accuracy measuring mark, over a plurality of images of said first mask pattern which have been transferred onto said photosensitive substrate in said first step, in a two-dimensional array extending in said first and second directions on said photosensitive substrate in units of said second exposure field with reference to a position of an image of said alignment mark by using said second exposure apparatus; and a third step of dividing an exposure area on said photosensitive substrate into a plurality of reference measurement areas in units of an area which is N1 times as large as a width of said second exposure field in said first direction on said photosensitive substrate and which is N2 times as large as a width of said second exposure field in said second direction on said photosensitive substrate, and measuring an amount of positional displacement between images of said first and second overlay accuracy measuring marks lying at mutually identical positions in a predetermined number of reference measurement areas selected from among said plurality of reference measurement areas, thereby obtaining a correction value which is used when the position of the image of said alignment mark transferred by said first exposure apparatus is detected by said second exposure apparatus on the basis of said measured amount of positional displacement; wherein an exposure position is corrected by using said correction value obtained in said third step when overlay exposure is to be carried out thereafter by using said second exposure apparatus with respect to a surface of said photosensitive substrate exposed by said first exposure apparatus.