Silicon nanocrystallites in buried SiOx layers via direct wafer bonding

A combination of SiO vapor-deposition and direct wafer bonding is used to p roduce buried layers of SiOx. By thermally induced decomposition, Si nanocr ystals embedded in SiO2 are obtained. Decomposition of the silicon suboxide is observed by studying the Si-O-Si stretching vibration in the infrared r ange. This phase separation process is found to start already at 400 degree s C and to be mostly complete after 1 h at 800 degrees C. Annealing at 1000 degrees C yields well established Si nanocrystallites of considerable dens ity with diameters about 4 nm buried in the interface layer between the bon ded silicon wafers. (C) 1999 American Institute of Physics. [S0003-6951(99) 01831-8].