Minimization of Image Placement Errors in Chromeless Phase Shift Mask Lithography

摘要

Image placement errors and their effect on process latitude are a remaining issue in the development of strong phase shift mask technology. In this work, we will review the various causes of image placement error for strong phase shift imaging, including both mask and stepper lens contributions. We will also review various methods of minimizing these image shift errors including the mask fabrication process, stepper lens improvement, and proper design of the lithography process. We will also present experimental results showing how aerial image asymmetry effects can be minimized by the use of an optimized resist process.