Patent ID: 7964503

Claim:
A method of patterning photoresist, comprising: forming an optically saturable absorption material over two or more regions of a semiconductor substrate, with at least two of the two or more regions differing in reflectivity relative to one another; forming the photoresist over the optically saturable absorption material; passing electromagnetic radiation through the photoresist and to the regions; at least some of the electromagnetic radiation that reaches the regions being reflected off from at least one of the regions; the difference in reflectivity of the regions patterning the reflected electromagnetic radiation; the directed electromagnetic radiation and patterned reflected electromagnetic radiation together exposing a first portion of the photoresist to a threshold dose of radiation while a second portion of the photoresist remains not exposed to the threshold dose; and selectively remove either the first or second portion of the photoresist relative to the other of the first and second portions.