Role of sidewall scattering in feature profile evolution during Cl-2 and HBr plasma etching of silicon

Coupling reactor-scale models of plasma etching equipment to device-scale models of feature profile evolution offers the potential for increased levels of virtual design of both capital equipment and process recipes. In this article, a combined reactor-and feature-scale model of crystalline silicon feature profile evolution is described, and simulation results of isolated trench and isolated line etching with Cl-2 and HBr plasmas are compared to experimental data. By incorporating reactor-scale predictions of plasma properties along with assumptions concerning the details of energetic particle scattering from surfaces, we are able to predict both the etch rate and the shape of evolving features. Important in the comparison to experiment is the proper prediction of ``microtrench{''}-free high aspect ratio trench etching in the case of HBr, contrasted with the occurrence of deep microtrenching when Cl-2 plasmas were used. These results suggest that a thorough knowledge of the details of energetic ion scattering from all evolving surfaces is required before accurate feature profile evolution predictions can be made. (C) 2000 American Vacuum Society. {[}S0734-211X(00)02602-0].