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

我们报道了一种仅使用电子束照射绘制Si图案（无需SiO_2掩模图案）的新型选择性生长方法。利用电子束辐照在蓝宝石表面的选择区域上生长Si膜。在照射之后，Si层不沉积在照射区域上，用Si_2H_6气体源分子束外延（MBE）不仅可以在（0112）和（0001）-Al_2O_3衬底的电子束非辐照区选择性生长Si薄膜，而且可以在（100）Si结构上选择性生长（100）-Al_2O_3薄膜。生长温度从700摄氏度到900摄氏度。使用电子束图形系统，在暴露于超过1.0 × 10 ^ [电子/cm ^2]的电子束的区域上不沉积Si层<16>。在5 kV和30 kV之间不依赖于电子束的加速电压。Al_2O_3基片的辐照表面由原来的表面变为氧还原表面。当电子剂量密度大于1 × 10 ~ 4电子/cm ~ 2时，表面的大部分氧原子被去除<16>，这与选择性外延的临界剂量密度相一致。XPS谱也表明，辐照后的表面由晶态Al_2O_3转变为类金属Al。选择性外延的驱动力可以认为是电子辐照形成的非晶表面。

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.