Low temperature selective epitaxial growth of SiGe layers using various dielectric mask patterns and process conditions

The SiGe film was deposited at a low temperature of 675-725 °C with various dielectric mask patterns and process conditions using reduced pressure chemical vapor deposition. Pattern shape and process conditions associated with the growth rate and the Ge composition of the selective epitaxial growth (SEG) have been examined for the SiH ₄ -GeH ₄ -H ₂ system. The objective was to understand the effect of pattern size at low temperature for the feasible device applications. The growth rates showed large non-uniformity of 1.4 depending upon the window width, 2-100 μm, of dielectric mask patterns. From the influence of the pattern shape/size and process parameters, the evolution of growth rates could be explained by the surface migration and the surface topology as well. After the surface migration control appearing dominantly at the initial stage, the surface topology became significant at the last part of the SEG process. The Ge composition is important to form the high quality SEG of SiGe films, so that it is important to optimize the flow rate of SiH ₄ , GeH ₄ , and total source gas.