Model-based optical proximity correction for resist reflow process

For the patterning of sub-100 nm contact holes, thermal reflow is suggested as a good method of,resolving the cost problems of resolution-enhancement technology and the new lithography technology. However, it is difficult to use this process in lithography process because the optical proximity effect of thermal reflow is quite severe. In this study, the optical proximity effects before and after thermal reflow are described. Resist reflow is modeled and simulated for a top-view image. For repeated contacts and random contacts, thermal reflow biases are modeled and compensated for pattern arrays. Simulation results agree well with the experiment results in a small error range according to baking temperature, time, and pitch size. For the optical proximity correction of thermal reflow, two-stage corrections, and model-based optical proximity corrections before and after thermal reflow, are described. The model-based optical proximity correction before thermal reflow can be required using pull-simulated images rather than an aerial image as pattern critical dimension shrinks down to sub-100 nm. The possibility of thermal reflow for the formation of a sub-100 nm pattern is shown by simulating a model-based optical proximity correction of a 45 nm contact hole.