The formation of SGOI structures with low dislocation density by a two-step oxidation and condensation method

A modified process of the Ge condensation method, which is a technique to form SiGe on insulator (SGOI) substrates for strained SOI-MOSFETs, is proposed to reduce threading dislocation density and the effectiveness of the proposed technique is demonstrated. The generation of threading dislocations, which is attributable to the rising behaviour of fragments of misfit dislocations formed at the SiGe/SOI interfaces, is suppressed by controlling the oxygen pressure during the ramping up period in the Ge condensation process. The threading dislocation density of SGOI substrates formed by the new method, which is evaluated by the enhanced secco-etching method, has been as low as 1 x 10(3) cm(-2) for the 230 nm thick SGOI layer with a Ge content of 20% and 75% relaxation.