PROPERTIES AND MECHANISM OF SI SELECTIVE EPITAXIAL-GROWTH ON AL2O3 USING ELECTRON-BEAM IRRADIATION

Si films were selectively grown on non-electron-beam-irradiated areas of (0112BAR) and (0001)alpha-Al2O3 substrates and (100)gamma-Al2O3 on (100)Si structures by Si2H6 gas-source molecular beam epitaxy (MBE) at growth temperatures from 700-degrees-C to 900-degrees-C. Si layers were not deposited on the areas exposed to an electron beam dose of more than 1.0 X 10(16) electrons/cm2 using an electron-beam graphicsystem. The irradiated surface of Al2O3 substrates was changed from the original surface to an oxygen-reduced surface. Most of the O atoms on the surface were removed at electron dose densities of more than 1 X 10(16) electrons/cm2, Which agrees with the critical dose density for selective epitaxy. X-ray photoelectron spectroscopy (XPS) spectra also showed that the surface consisted of metal like Al instead of crystalline Al2O3 after irradiation. The driving force of selective epitaxy can be considered to be the amorphous surface formed by electron irradiation.