High-quality strain relieved sige buffer prepared by means of thermally-driven relaxation and CMP process

Strained SiGe hetero-structures are of great importance for future Si large-scale-integrated applications, since both electron and hole mobility are expected to be largely enhanced. The strained layers are generally grown on strain-relaxed SiGe buffer layer, therefore, the carrier mobility strongly depends on the quality of the SiGe buffer layers. In this paper, we proposed a method to obtain high-quality strain-relaxed SiGe buffer layers on Si (100) by TDR (thermally driven relaxation) and CMP (chemical mechanical polishing) technique. We flattened the rough surface of the strain-relaxed SiGe buffer layers by CMP and successfully obtained the ultra-smooth surface, where the root mean square roughness was about 1nm with less than 10⁵/cm ² of threading dislocation density.