Patent ID: 7393614
Filing Date: 2008-07-01
Classification: G03F

Abstract:
1. A set of masks for the projection of structure patterns in a photosensitive layer on a semiconductor wafer in a projection system in each case, the structure patterns being arranged on the masks of the set and coordinated with one another, into the same comprising: a first mask having at least one essentially opaque structure element, the structure element being arranged at a first position on the first mask so that by projection of its image in the photosensitive layer on the semiconductor wafer, a still unexposed resist region is formed in the photosensitive layer; and at least one second mask assigned to the first mask, the second mask having at least one semitransparent region, the semitransparent region being arranged at a second position on the second mask, the second position corresponding to the first position on the first mask such that by projection of its image in the photosensitive layer on the semiconductor wafer at least part of the resist region is exposed in the photosensitive layer, wherein the semitransparent region has a radiated light transparency of more than 20 percent and less than 80 percent and wherein the transparency is selected so as to control diffraction effects at trimming mask gaps to obtain a maximum depth of focus.