Optimizing focal plane fitting functions for an image field on a substrate

摘要

An exposure tool includes an illumination source, a blazed phase grating reticle, a lens system, a focus sensor configured for maintaining a focus of the lens system, a stage holding a sample, and a controller. The controller is configured to control the illumination source and a position of the blazed phase grating reticle and the lens system relative to the stage to expose the sample according to a product shot map to generate a blazed phase grating sample. The controller is configured to adjust a focus offset of the exposure tool by product shot to improve focal plane fitting based on feedback generated from an analysis of images of the blazed phase grating sample.