A modified process of the Ge condensation method, which was a technique to form SiGe on insulator (SGOI) substrates for strained SOI-MOSFETs, was proposed to reduce threading dislocation density and the effectiveness of the proposed technique was demonstrated. The generation of threading dislocations, which was attributable to the rising behaviour of fragments of misfit dislocations formed at the SiGe/SOI interfaces, was suppressed by controlling the O pressure during the ramping up period in the Ge condensation process. The threading dislocation density of SGOI substrates formed by the new method, which was evaluated by the enhanced Secco-etching method, was as low as 103/cm2 for the 230nm-thick SGOI layer with a Ge content of 20 and 75% relaxation.

The Formation of SGOI Structures with Low Dislocation Density by a Two-Step Oxidation and Condensation Method. N.Sugiyama, S.Nakaharai, N.Hirashita, T.Tezuka, Y.Moriyama, K.Usuda, S.Takagi: Semiconductor Science and Technology, 2007, 22, S59-62