Line Edge Roughness Analysis for KrF Photoresists under sub 0.11 um Groundrules

Abstract

To maintain cost competitiveness for the 200 mm wafer production, the industry starts to explore production feasibility under groundrules smaller than 110 nm while maintaining the cost advantages given by the KrF exposure tools systems. The k1 factor under 110 nm will be below 0.35. It has the similar level of complexity in optical proximity correction compared to 65 nm at 0.93 NA with 193 nm exposure tools. However, due to that the KrF photoresists are originally designed for ground rules greater than 110 nm it is relatively unknown how feasible it is to extend their performance below 110 nm. As we know, in each photoresist design, there is a balance among three major performance indices, which are spatial resolution, photospeed, and pattern edge roughness. For example, a fast photoresist may not have the same resolution or pattern edge roughness performance as a slow photoresist, which may, of course, has low productivity. A good production resist usually has a good balance of all three parameters. This paper will explore the line edge roughness parameters under sub 110 nm design rules and will explore the performance dependence on imaging conditions. Classical photo process optimization result is shown and acceptable LWR performance is achieved. In addition, a comparison in line edge roughness among 3 production KrF photoresists will be made.