Epitaxial Growth of CeO_2(110) Layrs on Si(100) Substrates

硅衬底上的外延二氧化铈（CeO_2）层对于在硅衬底上生长具有紧密晶格匹配的高质量外延绝缘材料，以及在微电子领域的应用，如小型化稳定电容器、绝缘体结构上的硅和高温超导体与硅衬底之间的缓冲层都具有重要的意义。在研究CeO_2在Si上的外延生长过程中，明确了在Si（111）上生长的CeO_2（111）层虽然在低温和高结晶度下生长，但在Si（100）上生长的CeO_2层具有（110）取向，并且需要更高的衬底温度（- 820 C）。CeO_2（110）层呈现由CeO_2[100]||Si[110]和CeO_2[110]||Si[110]组成的双畴结构。结果表明，在<110>方向的最佳切割量为2.5‰的衬底上可以实现单晶CeO_2（110）层。对于硅基微电子器件，需要更多的阳离子和低温工艺。为了降低CeO_2（110）层在Si（100）衬底上的外延生长温度，认为需要离子、电子和光子等高能粒子的外在辅助，为生长表面吸附原子和/或分子的重排提供足够的能量。本课题研究了电子束蒸发法在Si（100）衬底上外延生长CeO_2（110）层时电子入射的影响。采用两种生长方法：衬底偏压下的蒸发（偏压蒸发）和电子束辅助蒸发。在偏置蒸发过程中，蒸发粒子中的小部分带电粒子被偏置电位吸引到衬底表面，有利于CeO_2的外延生长。发现来自蒸发源的电子在正偏压下成功地降低了蒸发外延温度。电子束辅助蒸发在降低外延温度和提高晶体质量方面都有较大的效果。该方法是一种新型的电子束同步辐照蒸发方法，与偏置蒸发相比，具有更大的变化范围和对电子辐照能量和电流密度的更好控制。外延温度降至710℃，即：，与传统方法相比，其含量降低了100以上。阐明了电子束辅助蒸发作为一种先进的薄膜生长方法是非常有前途的。少

Epitaxial cerium dioxide (CeO_2) layrs on silicon substrates are of great interest both for growing high-quality epitaxial insulating materials on Si with close lattice matching and for applications to microelectronics such as miniaturized stable capacitors, silicon on insulator structures and buffer layrs between high-temperature superconductors and Si substrates. In the course of the investigation on the epitaxial growth of CeO_2 on Si, it has been clarified that although CeO_2(111) layrs grow on Si(111) at low temperatures with high crytallinity, CeO_2 layrs grown on Si(100) have a (110) orientation and require a higher substrate temperature of - 820ﾟC.Moreover, the CeO_2(110) layr tends to have a double domain structure consisting of a mixture of CeO_2[100]||Si[110] and CeO_2[110]||Si[110]. It has been found that single-crytalline CeO_2(110) layrs are realized using substrates with an optimum miscut of 2.5ﾟ towards the <110> direction. For silicon-based microelectronic device fabri … More cation, low-temperature processes are strongly desired. In order to lower the epitaxial growth temperature of CeO_2(110) layrs on Si(100) substrates, it is thought that some extrinsic assistance by energetic particles such as ions, electrons and photons, is needed to give sufficient energy for the rearrangement of adsorbed atoms and/or molecules at the growing surface.In this research project, the effect of electron incidence is studied in the epitaxial growth of CeO_2(110) layrs on Si(100) substrates by electron-beam evaporation. Two growth methods are employed : evaporation under substrate bias application (bias evaporation) and electron-beam assisted evaporation. In bias evaporation, a small portion of charged particles among evaporating particles are attracted to the substrate surface by the bias potential and facilitate the CeO_2 epitaxial growth. It is found that electrons from an evaporation sosurce lead to a successful epitaxial temperature lowering in evaporation at positive bias. electron-beam assisted evaporation has much greater effect in both epitaxial temperature lowering and the crystalline quality improvement. This method, a novel method of evaporation with simultaneous electron-beam irradiation has advantages over bias evaporation because of the wider variable range and greater control of the energy and current density of electron irradiation. The epitaxial temperature is lowered to 710ﾟC,i.e., more than 100ﾟC low compared with that of the conventional method. It is clarified that the electron beam assisted evaporation is very promising as an adavanced method for thin film growth. Less