Information theoretical aspects in coherent optical lithography systems

Abstract

Optical lithography is extensively used in micro and nano scale semiconductor fabrication. However, the information transmission mechanism in lithography systems is not yet completely understood. This paper studies and analyzes the lithography imaging process from an information theory perspective. The optical lithography system is regarded as an information channel, an approximate statistical model is built to depict the imaging process, and information theoretical aspects of coherent optical lithography systems are studied. Based on that, we derive the mutual information between the mask pattern and print image, as well as the maximum information transfer (MIT) of the coherent lithography system. This paper also reveals and discusses the physical meaning of MIT in the lithography imaging process. Finally, a method to calculate the theoretical limit of image fidelity using the MIT is proposed and verified by a set of simulations.