The stacking faults and their strain effect at the Si/SiO2 interfaces of adirectly bonded SOI (silicon on insulator)

SOI (silicon on insulator) was fabricated through the direct bonding of a h ydrophilic single crystal Si wafer and a thermally oxidized SiO2 film. The hydrophilic Si was formed by treating the surface with modified SC-1 (NH4OH :H2O2:H2O) solution. The wafers were directly bonded to each other and were annealed at the temperature of 1200 degrees C for 1 h. By removing the oxi de film, it was possible to examine the stacking faults at the bonding inte rface and the oxidation interface. The distributions of the stacking faults were showing different behaviors between the bonded and the void regions. While the stacking faults of high density were distributed in the ordered r ing-like fashion in the bonded region, the stacking faults of linear orient ation were shown in the void region as shown in the thermal oxidation. To i nvestigate the relation between the stacking faults and the lattice deforma tion at the interface, the lattice strains were measured through CBED (conv ergent beam electron diffraction) analysis using transmission electron micr oscopy. It was found that both the thermal and the intrinsic strains were s trongly influenced by the stacking faults. (C) 1999 Elsevier Science S.A. A ll rights reserved.