Formation and ordering of self-assembled Si islands by ultrahigh vacuum annealing of ultrathin bonded silicon-on-insulator structure

Thermal agglomeration of Si in an ultrathin -10 nm.bonded silicon-on-insulator SOI.wafer was studied by means of X-ray photoelectron spectroscopy XPS.and atomic force microscopy AFM.. It was found that annealing in an ultrahigh vacuum UHV.causes the formation of square-shaped holes whose sides are parallel to the 011:directions. Within the hole, single-crystalline Si islands are densely formed on the buried SiO2 with an ordered alignment in the 013:directions. The lateral size and the height of a typical island near the center of the hole are about 500 and 70 nm, respectively, and the island is surrounded by facets of 1114, 1134and 1004 crystal planes. The initial process of hole opening and island formation is discussed. q2000 Elsevier Science B.V. All rights reserved.