Analysis of Reticle Deformation, Reduction Ratio and MEEF of Future Optical Lithography

摘要

As a result of aggressive line width shrinking of semiconductor devices in the recent years, the requirements for advanced reticles are getting more and more stringent. Therefore, it is beneficial to consider increasing the reduction ratio of projection optics in order to relax the reticle tolerances. This paper discusses quantitatively the reticle, CD, DOF and overlay accuracy requirement listed in ~2the 1999 International Technology Roadmap for Semiconductor (ITRS) roadmap. Our simulation suggests mask drawing accuracy needs to be further improved for better CD control accuracy. Increasing reduction ratio to 6x is also another way to meet the line wicth requirement. Productivity enhancement with 6x reduction in comparison to 4x reduction ratio is also shown.