Low-dislocation relaxed SiGe grown on an effective compliant substrate

Abstract

An effective compliant substrate was successfully fabricated for growth of high quality relaxed SiGe templates. The compliant substrate was fabricated by synthesizing a 20% B₂O₃ concentration borosilicate glass in the silicon on insulator wafers through boron and oxygen implantation followed by high temperature annealing. Substrates with 5%, 10% and 20% B₂O₃ were used for 150 nm Si_0.75Ge_0.25 epitaxy. Double-axis x-ray diffraction measurements determined the relaxation and composition of the Si_1−xGe_x layers. Cross-sectional transmission electron microscopy was used to observe the lattice of the SiGe epilayer and the Si substrate, dislocation density and distribution. Raman spectros-copy was combined with step etching to measure the samples. For 20% BSG sample, the strain in the thin Si layer was calculated from the Raman shift and it matched the results from DAXRD very well. The density of threading dislocation on the surface of 500 nm Si_0.75Ge_0.25 layers was 2×10⁴ cm⁻² for the sample on the 20% borosilicate glass substrate. This method is promising to prepare effective compliant substrate for low-dislocation relaxed SiGe growth.