EFFECTS OF BORON CONCENTRATION ON Si1-XGEX PROPERTIES FOR INTEGRATED MEMS TECHNOLOGY

The effects of boron (B) concentration on the chemical, electrical, and mechanical properties of p+ polycrystalline germanium (poly-Ge) and p+ polycrystalline silicon-germanium (poly-Si 1-x Ge x ) films are reported. Experimental results show that heavy B doping is beneficial for increasing the deposition and etch rates, as well as for reducing the surface roughness of p+ poly-Ge sacrificial films. However, structural poly-Si 1-x Ge x films become more compressive, and show a slight increase in strain gradient, with increasing B content. Analytical models fit to the experimental data for conductivity, residual stress, and strain gradient have been generated as a guide for co-optimization of B and Ge content.