Fabrication of SiGe Virtual Substrates by Ion Implantation Technique

Abstract

We have developed a new SiGe virtual substrate fabrication technique where pre-ion-implantation is employed. In this method, prior to growth of SiGe layers, defects are intentionally introduced in the vicinity of Si substrate surfaces via implantation of relatively heavy ions, such as Ar+, Si+ and Ge+. Thin SiGe layers are grown on the ion-implanted Si substrates and the subsequent annealing considerably enhances the strain relaxation of the SiGe layers due to implantation-induced defects working as dislocation generation sources. As a result, extremely thin (100 nm) and largely-relaxed SiGe layers with atomically flat surfaces and very uniform strain distribution are obtained. These thin SiGe virtual substrates can be applied to the fabrication of strained-Si nMOSFETs and the significant mobility enhancement over the bulk Si device is obtained. These results clearly indicate that the ion implantation technique is very promising for realization of high-performance Si/Ge heterodevices based on SiGe virtual substrates.