Formation of SGOI Structures with Low Dislocation Density by Two Step Oxidation and Condensation Method

SiGe on insulator (SGOI) is a typical template substrate for strained Si-on-insulator (SOI) structures, which can enjoy both benefits of the mobility enhancement by strained channels and the low junction capacitance by SOI structures. In order to fabricate the high performance MOSFET, formation of the highly strained Si layers on SGOI without dislocations and defects is quite important. This means that, highly relaxed crystal layers with high Ge content and a low dislocation density are mandatory for the SGOI substrates. We have already proposed the Ge condensation method to form SGOI substrates, where SiGe / SOI structures are oxidized and, as a result, Ge atoms are condensed into remaining thin SGOI layers. It has also been revealed that, during the initial stage of the condensation process, misfit dislocations are formed at the interface of SiGe layers and SOI substrates and their fragments rise up toward the surface, which is a mechanism for the generation of remaining threading dislocations. In this paper, a new modified process of the Ge condensation method, which is based on the previous insight into the dislocation generation mechanism, is proposed to form SGOI with low threading dislocations and the effectiveness is demonstrated