Realistic surface reaction modeling for 3D feature profile simulation of fluorocarbon-based plasma etch process

Abstract

One of the emerging challenges in next generation device is to achieve the high aspect ratio contact holes using fluorocarbon plasma. However, it is regarded that the predictable simulation for these processes is beyond current science and technology due to their inherent complexity of fluorocarbon plasma. To address these issues, we have developed a realistic and ultrafast 3D topography simulator of semiconductor plasma processing coupled with zero-D bulk plasma models. In this work, we introduce a surface reaction model to capture the realistic surface reaction phenomena under the fluorocarbon plasma. This surface reaction model is based on a two-layer model that considers plasma etch kinetics at a mixed layer of fluorocarbon and target material under the existence of a steady-state fluorocarbon passivation layer during plasma etching. The key parameters in this surface reaction model are extracted by previously reported data or fitting experimental data from several diagnostic tools in a fluorocarbon plasma system. Based on this model, useful information such as the thickness of polymer passivation layer, and deposition/etch rate can be obtained by functions of the incidence ion energy, neutral and ion fluxes. Finally, we demonstrate that 3D feature profile simulation coupled with this realistic surface reaction model can lead to better understanding of the emerging issues in plasma etch process, such as necking, bowing, etch stops and twisting during high aspect ratio contact hole etch in semiconductor plasma process.