Patent ID: 7393613

Claim:
A set of at least two masks for the projection of structure patterns, each structure pattern being formed on the masks and coordinated with one another by a projection system into the same photosensitive layer arranged on a semiconductor wafer, the projection system having a resolution limit for a lateral dimension of an opening projected onto the semiconductor wafer from a mask, comprising: a first mask including a semitransparent or nontransparent first layer, which is arranged on a first substrate and in which at least one first opening is formed at a first position, the first opening having a first lateral dimension, which is greater than the resolution limit; and a second mask assigned to the first mask, the second mask including a semitransparent or nontransparent second layer, which is arranged on a second substrate and in which at least one dummy structure assigned to the first opening is formed at a second position, the dummy structure having a second lateral dimension, which is smaller than the resolution limit of the projection system wherein the first position on the first mask identically corresponds to the second position on the second mask, wherein one of the first and second masks is an alternating phase mask, wherein the other of the first and second masks is a trimming mask having at least one further opening for the exposure of a region in the photosensitive layer, which arises on account of a phase conflict in the case of an exposure with said one of the first and second masks, and wherein the second lateral dimension is selected to improve a depth of focus in a combined double exposure by the first and second masks.