Illumination uniformity improvement in digital micromirror device based scanning photolithography system.

ABSTRACT

Illumination uniformity in photolithography systems determines the dimensional difference across the entire lithographic substrate. However, traditional lithography system relies on expensive and complex illumination system for achieving uniform illumination. In this paper, we propose a simple and cost-effective method based on the modulation of digital micromirror device to improve illumination uniformity. The modulation according to a digital mask achieved via an iteration program improves the uniformity to be above 95%. We demonstrate the effectiveness of the method by experimentally fabricating a linear grating. By implementing this method, the maximum dimensional difference is decreased from 3.3µm to 0.3µm. Further simulations indicate that higher uniformity is achievable once the field of view on the DMD is divided into smaller subregions.