Patent ID: 6320659
Filing Date: 2001-11-20
Classification: G01B,G03F

Abstract:
A clearance measuring device measuring a clearance between a photomask and a plate for adjusting said clearance between said photomask and said plate to a prescribed value in accordance with the measurement data in an exposure apparatus transferring a pattern on said photomask onto said plate by directing light to said plate through said photomask, said photomask having a clearance measuring mark in a prescribed position on a surface opposite to said plate, comprising:at least one light sensor for sensing an image or shadow of said clearance measuring mark projected on said plate by irradiating said clearance measuring mark and a region including said clearance measuring mark with light;calculating means calculating a clearance between said photomask and said plate based on a relative positional relationship between said clearance measuring mark and said image or said shadow of said clearance measuring mark; andclearance adjusting means for adjusting the clearance between said photomask and said plate to a prescribed value by relatively moving said photomask and said plate based on the calculation result from said calculating means.