Patent ID: 7122453

Claim:
A method of forming a radiation-patterning tool, comprising: providing a substrate comprising silica and having a substrate surface; forming a structure comprising a first material on the substrate surface, the structure being configured to attenuate a portion of radiation passing through the substrate to define a pattern of radiation intensity, the passing of radiation through the substrate and structure producing a first shift that defines a first phase; and forming at least one subresolution assist feature on the substrate surface proximate and laterally spaced from the structure to modify the pattern of radiation intensity, the subresolution assist feature comprising a second material that differs in composition from the first material and is transmissive of at least a portion of the radiation; the substrate having a first thickness and the subresolution assist feature having second thickness; the ratio of the first thickness relative to the second thickness defining a second phase, the second phase being approximately in phase with the first phase.