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 m odels of feature profile evolution offers the potential for increased level s 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 pro perties along with assumptions concerning the details of energetic particle scattering from surfaces, we are able to predict both the etch rate and th e shape of evolving features. Important in the comparison to experiment is the proper prediction of "microtrench"-free high aspect ratio trench etchin g in the case of HBr, contrasted with the occurrence of deep microtrenching when Cl-2 plasmas were used. These results suggest that a thorough knowled ge 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].