The mechanism for the stress-relaxation in the Ge condensation induced by H(+) irradiation-assisted oxidation method was investigated. Relaxation ratio of Si(0.7)Ge(0.3) (thickness: 28 nm) formed by medium dose H+ irradiation (5 x 10(15) cm(-2)) and oxidation at 1100 degrees C was limited to 35%. Post-annealing (1200 degrees C) improved this value significantly (70%), though defect density was found to be kept at low density (<10(6) cm(-2)). However, the height of cross hatches was increased (from 0.6 nm to 4.1 nm) after post-annealing. Based on these results, local-area slipping model was proposed, where slipping at SiGe/SiO(2) interface of local areas surrounded by cross hatches enhanced stress-relaxation. This model could quantitatively explain the stress-relaxation enhanced by combination of H(+) irradiation, oxidation-induced Ge condensation, and postannealing. (c) 2008 Elsevier B.V. All rights reserved.