Articles you may be interested inFeature profile evolution during shallow trench isolation etch in chlorine-based plasmas. II. Coupling reactor and feature scale models 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.

We have studied the effects of source and bias powers, pressure, and feed gas composition on the shapes of SiO2-masked crystalline silicon features etched in a transformer-coupled high density plasma system. Higher etching rates were obtained at higher source and bias powers, and higher pressure. The etching rates of isolated and nested trenches, isolated lines, and holes were nearly the same, indicating a negligible pattern density dependence. We did, however, observe a very weak decrease in etch rates with increasing aspect ratio at 2 mTorr in a pure Cl2 plasma. At 10 mTorr, no aspect ratio dependence was observed, except at the highest source and bias powers. Microtrenching was observed under certain plasma conditions and could be reduced by using higher bias powers. At 10 mTorr in a pure chlorine plasma, we observed a slight taper at the bottoms of the etched features and the formation of narrow microtrenches near feature corners. At 2 mTorr, the microtrenches were broader and overlapped near the center of narrow trenches to form pyramid-shaped trench bottoms. When a HBr plasma was used instead of Cl2, the etching rate decreased by 50% but the etching profiles were more vertical and the trench bottoms were flat. Isolated lines etched in the HBr plasma, however, revealed broad but shallow microtrenches near the edges of the line, suggesting that the flat trench bottoms were a result of broad microtrenches that overlapped. Trenches of 3 μm depth and aspect ratios of 7 have been obtained using either HBr or Cl2, exhibiting similar microfeatures as observed when etching shallower trenches.