Investigation on solid phase epitaxy of deposited SiGe film on a Si substrate

The solid phase hetero-epitaxy of amorphous SiGe on a Si(100) substrate has been investigated. The initial SiGe was deposited by ion beam sputtering at room temperature from a composite target of Si and Ge wafers. The solid phase epitaxial SiGe layer was formed through a boron diffusion, thermal annealing and oxidation process, respectively. The boron diffusion was carried out at 970 °C and then 1065 °C for redistribution, thermal annealing was carried out at 1000 °C in a N₂ ambient, and oxidation at 900 °C in steam, dry O₂ and steam ambient subsequently. Auger electron spectroscopy, X-ray diffraction, scanning electron microscopy, Rutherford backscattering spectroscopy/channelling, cross-sectional transmission electron microscopy, and Raman Spectroscopy were used to characterize the SiGe film. The experimental results indicate that through a boron diffusion, Ge atoms diffuse considerably generating a SiGe layer with a lower Ge concentration than that of the as-deposited film, while the thermal annealing makes the amorphous SiGe layer crystallize, for the oxidation of the a-SiGe/Si structure, a newly formed SiGe/Si heterostructure with a higher Ge concentration than that of the as-deposited film has been found due to the selective oxidation of Si at the applied temperature. © 1997 Elsevier Science S.A.