How to Print 100 nm Contact Hole with Low NA 193 nm Lithography

摘要

The continuous shrinkage of critical dimensions on 300 mm wafers has driven ArF lithography to resolve very small features for the next generation node. But the depth of focus (DOF) for 100 nm contact holes with a low NA of 0.75 is not adequate. Some resolution enhancement techniques (RETs), such as high transmission attenuated phase shifting masks, increase isolated contact hole DOF. Annular or quadrapole illumination improves dense hole resolution. However, they still cannot meet the requirement of logic circuit fabrication. To delineate 100-nm contact holes at 200-nm pitch, the resist process for 193 nm light was studied for the feasibility of a robust manufacturing process. In this paper we will discuss how to improve the process conditions of the thermal flow technique, as well as optimizing the illumination settings, prebake / post exposure bake temperatures, the mask dimensions and thermal flow temperature. Moreover, we will show the process window after the thermal flow process with optical proximity correction.