Precise and practical 3D topography simulation of high aspect ratio contact hole etch by using model optimization algorithm

Abstract

High Aspect Ratio Contact (HARC) hole etch is one of the most challenging processes that require many efforts to optimize etch condition. As the aspect ratio increases, novel issues, such as “distortion” and “twisting,” have been highlighted. Since they cause nonaxisymmetric features along the hole axis, it is difficult to understand the etch mechanism correctly, and therefore, taking a 3D profile image is essential to evaluate the exact etch profile. In this study, we created the models for HARC etch with a cell-based Particle Monte Carlo topography simulator by fitting both vertical and horizontal cross-sectional profiles carefully to the experimental results. Moreover, we attempted to apply a model optimization algorithm. By collaboration of human and the algorithm, modeling engineers can minimize a try-and-error approach, and a precise 3D simulation model can be created much faster than before. As a result, the distortion and twisting profiles were reproduced very well on the simulator, and thus, it is expected that the simulator can be utilized as a practical tool for an assistance of process optimization.