A study of process parameter control for nanopattern

Abstract

As lithography technology pushes to the nanoline dimensions, even less drastic changes during photoresist processes can have a non-negligible impact on proximity behavior; thus, these changes can affect the optical proximity correction rules and models. In this study, after the descriptions of the whole-process parameters, the impact on proximity behavior is described and analyzed by using the quantitative sensitivity of these parameters on the critical dimension. Our lithography simulator shows similar behavior to a commercial tool in the critical dimension variation of each tool due to process parameters. By using this benchmark home-made lithography simulator and response surface methodology, the most dominant response parameters of each process in terms of critical dimension and side-wall angle are found to be numerical aperture of the projection lens system and time for the soft-bake process. The most effective process for the 193-nm chemically amplified resist is found to be the post-expose bake process for critical dimension and side-wall angle. Although the prediction errors are less than 10% of the pattern size by using the threshold-energy resist model, the effect on optical proximity correction rules and the characterization of the mask error enhancement factor can be easily controlled to below 5% of pattern size by using these dominant process parameters.