In-situ Si selective-epitaxial grown SOI structures using Electron beam graphic system

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We report a new type selective growth method using only electron beam irradiation for drawing Si patterns (without SiO_2 mask patterns). The Si films are grown on selective areas of sapphire surface using electron beam irradiation. After irradiation, Si layers are not deposited on the irradiated areas, but are grown selective-epitaxially only on the non-irradiated areas.Si films can be selectively grown not only on electron-beam non-irradiated areas of (0112) and (0001) -Al_2O_3 substrates but also (100) -Al_2O_3 on (100)Si structures by Si_2H_6 gas-source molecular beam epitaxy (MBE) at growth temperatures from 700ﾟC to 900ﾟC. Si layers were not deposited on the areas exposed to electron beam more than 1.0x10^<16> [electrons/cm^2] using an electron-beam graphic-system. There are not dependence on an acceleration voltage of electron beam between 5kV and 30kV. The irradiated surface of Al_2O_3 substrates are changed from the original surface to an oxygen-reduced surface. Most of the O atoms of surface are removed at electron dose densities more than 1x10^<16> electrons/cm^2, which agrees with the critical dose density for selective epitaxy. XPS spectra also shows that the surface consisted of metal-like Al instead of crystalline Al_2O_3 after irradiation. The driving force of the selective epitaxy can be considered the amorphous surface formed by the electron irradiation.