Rigorous electromagnetic modeling of near-field phase-shifting contact lithography

Abstract

Electromagnetic absorption in a photoresist layer sandwiched between a silicon substrate and a quartz binary phase-shifting mask (employed in near-field phase shift contact lithography) is theoretically analyzed. A rigorous coupled-wave analysis is used to compute the distribution of specific absorption rate (SAR) in the photoresist layer on either monochromatic and polychromatic illumination. The nonuniform distribution of the SAR in the photoresist layer for the printing of high-aspect-ratio features is systematically examined in relation to the geometric dimensions of the binary phase mask, the photoresist layer thickness, and the polarization state of the incident plane wave. Two methods for the improvement of feature resolution and profile are also discussed.