FOCAL PLANE ADJUSTED PHOTOMASK AND METHODS OF PROJECTING IMAGES ONTO PHOTOSENSITIZED WORKPIECE SURFACES

摘要

FOCAL PLANE ADJUSTED PHOTOMASK AND METHODS OF PROJECTING IMAGES ONTO PHOTOSENSITIZED WORKPIECE SURFACES In the operation of a projection printer photomasks, the patterns of which are protected by coverplate, are used interchangeably with other photomasks, the patterns of which are located at an open surface thereof. The photomasks feature shims which space the patterns away from a plane of support surfaces of a mounting chuck by a precise distance equal to the shift of the object plane with respect to an image plane because of the presence of the coverplate in the optical path of the projection printer.