Investigation of feature orientation and consequences of ion tilting during plasma etching with a three-dimensional feature profile simulator

Pattern transfer in microelectronics fabrication using plasma-assisted etching processes is being challenged by the three-dimensional (3d) structures of devices such as fin field effect transistors. Etching of 3d structures typically requires a longer over-etch time to clear material in corners, introducing additional selectivity challenges to maintain feature scale critical dimensions. Feature open area, orientation, aspect ratio, and proximity to other nearby structures can influence the outcome of the etch process. In this paper, the authors report on the development and application of a 3d profile simulator, the Monte Carlo feature profile model in the investigation of aspect ratio, and feature orientation dependent etching. In these studies, energy and angularly resolved reactant fluxes were provided by the hybrid plasma equipment model. Results from the model were validated with trends from experimental data. Using reactant fluxes from He/Cl2 and Ar/Cl2 inductively coupled plasmas, etching of two dimensional (2d) and 3d structures in the context of ion tilting and orientation of the feature was investigated.