Cross technology reticle (ctr) or multi-layer reticle (mlr) cdu, registration, and overlay techniques

Abstract

Methods for reducing reticle transmission differences and for optimizing layer placement for overlay in MTRs and CTRs are disclosed. Embodiments include providing a reticle having a prime area and a frame area surrounding the prime area; determining RT differences across the prime area; and providing RT adjustment structures on the reticle to decrease the RT differences. Other embodiments include grouping multiple layers of a semiconductor production flow, the layers for each group having an RT difference less than a predetermined value; and placing the layers on plural ordered reticles of a reticle set, each reticle having multiple image fields, by selecting, for each reticle, layers from a single group and optimizing placement of the layers for overlay. Other embodiments include selectively rotating image fields on a reticle having multiple image fields to improve overlay, or optimizing placement of DDLs on CTRs by placing each design orientation on a different reticle.