Photomask with illumination control over patterns having varying structural densities

Abstract

A photomask is constructed to include a substrate, a transmission control layer, and a reflective layer. The photomask may be used to pattern a photoresist layer deposited during the manufacturing process of semiconductor integrated circuits, and may be particularly useful for patterning photoresist layers in situations where the density of the structures varies across the photoresist layer and thus varies across the corresponding pattern on the photomask. The photomask can compensate for the different structural densities by adjusting the thickness of the transmission control layer. Areas of the photomask that have a lower structural density and therefore have a higher light intensity can be formed to have a thicker transmission control layer as compared to areas which have a higher structural density and which already have a lower light intensity.

Dependencies are inferred from the claim text.