Basic research on selective epitaxy in very limited areas

提出了一种电子束辐照在A12O3上制备硅外延纳米结构的新工艺。我们发现，电子束辐照对A12O3表面氧原子的解吸引起了表面改性，并利用这一现象进行了选择性外延生长的研究。在（0112）和(0001)α - a12o3基片和(100)γ - a12o3基片的非电子束辐照区，采用Si2H6气源MBE在（100）Si基片上选择性地生长Si薄膜，生长温度为700 ~ 900 C。该方法主要包括以下两个步骤；电子束辐照A12O3表面，然后用Si2H6气源分子束外延（MBE）生长Si。经过这些工艺，可以选择性地在A12O3上制备硅纳米结构。硅纳米结构只能在非辐照电子束区域生长。由于这种方法不需要传统选择性外延中使用的氧化物掩膜，因此有可能实现进一步的微小型化。硅的选择性生长机制是基于A12O3表面氧原子的脱附和表面变化从A12O3转变为金属状结构。研究了电子束辐照在A12O3表面选择性外延生长制备硅介观结构的新方法。原子力显微镜（AFM）和扫描电镜（SEM）观察得到直径250nm、高度30nm的Si点。经证实，这些位置和大小是统一控制的。在蓝宝石表面均匀形成宽250nm、高30nm的Si丝，非晶态Al氧化区几乎不存在Si核。我们发现在蓝宝石衬底上形成了位置和尺寸可控的硅介观结构。通过这种方法得到的硅介观结构的形状在很大程度上取决于电子束剂量密度。采用固体源Al和N2O气源MBE代替TMA减少碳污染，在SOI结构的Si上研究了高结晶质量的A12O3薄膜。采用硅离子注入法研究了A12O3单晶膜的选择性蚀刻方法。该方法可用于SOI器件。少

We present a new fabrication process of Si epitaxial nanostructures on A12O3 by electron beam irradiation. We found that an A12O3 surface was modification was caused by desorption of wxygen atoms from the surface by electron beam irradiation and research on selective epitaxial growth using this phenomenon are being conducted. We confirmed that Si films were selectively grown on non-electron-beam irradiated areas of (0112) and (0001) alpha-A12O3 substrates and (100) gamma-A12O3 on (100) Si substrates by Si2H6 gas-source MBE with growth temperatures ranging from 700ﾟC to 900ﾟC.This method consists mainly of following two procedure ; electron beam irradiation on the A12O3 surface, and then Si growth with Si2H6 gas source molecular beam epitaxy (MBE). After these processes, Si nanostructures are selectively fabricated on A12O3. si nanostructures could be grown on only non-irradiated electron beam areas. Because this method does not require oxide masks that are used in conventional selectiv … More e epitaxy, it might be possible to achieve further micro miniaturization. Si selective growth mechanism is based on desorption of oxygen atoms from A12O3 surface and transformation of the surface changes from A12O3 to metal-like Al.A new fabrication method of Si mesoscopic structures on A12O3 by selective epitaxial growth using an electron beam irradiation was investigated. From observation with atomic force microscope (AFM) and scanning electron microscope (SEM), Si dots of 250nm diameter and 30nm height were obtained. It was confirmed that those positions and size were uniformly controlled. Si wires of 250nm width and 30nm height were uniformly formed on the sapphire and Si nucleus was hardly existed on the amorphous Al oxide areas. we found that position and size controlled Si mesoscopic structures were formed on a sapphire substrate. The shapes of the Si mesoscopic structures by this method depend greatly on the electron beam dose density.High-crystalline quality A12O3 films on Si for SOI structures were also investigated using solid source Al and N2O gas source MBE instead of TMA to reduce carbon contamination. Selective etching method of A12O3 single crystalline films were developed using Si ion implantation method. This method could become useful to SOI devices. Less