Patterning process

A patterning process is performed on a semiconductor wafer coated with a bottom layer, a middle layer and a photoresist layer having a starting thickness. The patterning process includes: performing an exposure step including exposing the semiconductor wafer using a mask that includes a feature which produces an intermediate light exposure in a target area followed by processing that creates openings in the photoresist layer in accordance with the mask and thins the photoresist in the target area due to the intermediate light exposure in the target area leaving thinned photoresist in the target area; performing middle layer etching to form openings in the middle layer aligned with the openings in the photoresist layer, wherein the middle layer etching does not remove the middle layer in the target area due to protection provided by the thinned photoresist; and performing trim etching to trim the middle layer in the target area.