Focus : The Critical Parameter For Submicron Optical Lithography :Part 2

Depth of focus requirements and contributions to the focal error budget for submicron optical lithography are reviewed. Models are presented which estimate depth of focus in both thin and thick layers of photoresist. The effects of resist refraction on usable depth of focus are considered. Measurements of image plane tilt, curvature, and astigmatism in 5X reduction lenses collected using an automated, in situ, aerial image monitor are analyzed.