Study on the Epitaxial Growth of Oxide Films in Sputtering focusing on Negative Oxygen Ion Behavior

在本项目中，我们利用感应耦合等离子体辅助溅射技术在单晶氧化镁衬底上沉积了二氧化钛薄膜。此外，我们还研制了一种利用可移动多靶点实现原位连续沉积的新型溅射装置。通过在氧化镁衬底上沉积二氧化钛薄膜，我们发现金红石型晶体薄膜具有面内两个取向。解释了较高的等离子体密度和较低的靶自偏压对金红石型TiO2高温稳定相外延生长的影响。根据与合作者新藤春夫教授合作的朗缪尔探针研究，负氧离子的动力学效应被认为是非常重要的问题，因为它们的作用不同于正离子。负氧离子和活性氧原子的作用这个问题将继续…更多信息将在下一项研究中介绍。除了在氧化镁衬底上生长二氧化钛外，我们还在钛酸锶衬底上沉积了掺Nb的二氧化钛薄膜。在此基础上，利用电感耦合等离子体辅助溅射技术沉积了二氧化钒(VO2)薄膜，得到了电阻率为10~(-4)&gt；Ωcm量级的透明二氧化钒薄膜。作为一个有希望的结果，我们得到了化学计量比的VO_2薄膜，它在65℃左右的较低温度下表现出金属-绝缘体的转变。这种具有跃迁特性的薄膜可以应用于新概念的开关和存储器件。新制造的溅射设备具有原位可调的双靶功能，可以连续溅射不同类型的材料。作为代表，我们在预沉积的Al膜上沉积了铁磁性的Co膜。结果表明，在Al底层上成功地沉积了无磁控效应的晶态HCP-Co薄膜，通过引入原位连续沉积技术，显示了实现高性能多层膜生长的潜力。较少

In this project, we performed depositions of titanium dioxide films on single crystalline MgO substrates by using inductively coupled plasma (ICP)-assited sputtering. In addition, we fabricated a new sputtering device which can realize in-situ sequential depositions utilizing movable multi targets.Through depositions of titanium dioxide (TiO_2) films on MgO substrates, we showed oriented growth of rutile-type crystalline films having in-plane two orientations. It is interpreted that higher density plasma production and lowered target self bias voltage in ICP-assisted sputtering brig about epitaxial growth of high-temperature stable phase of rutile Ti0_2. Based on the Langmuir probe studies which were done by the cooperation with co-researcher, Professor Haruo Shindo, kinetic effects of negative oxygen ions are supposed to be very important issue due to their effects different from positive ions. This issue of the roles of negative oxygen ions and active oxygen atoms is to be continued … More in next study. In addition to the TiO_2 growth on MgO substrates, we performed deposition of Nb-doped TiO_2 films on SrTiO_3 single substrates. As the results, transparent TiO_2 films with lower resistivity on the order of 10^<-4> Ωcm were achieved.Further, we deposited vanadium dioxide (VO_2) films by using ICP-assisted sputtering technique. As a promising result, we obtained stoichiometric VO_2, films which show metal-insulator transition at relatively low temperature around 65℃. Such film with transition characteristic can be applied to newly concept switching and memory devices.Newly fabricated sputtering device with in-situ changeable two targets enabled sequential sputter deposition of different kinds of material. As a representative, we performed depositions of ferromagnetic Co film on pre-deposited Al film. As the result, crystalline hcp-Co film was deposited on Al under-layer without the magnetron effect, revealing the potential ability to realize superior multi-layered film growth by the introduction of in-situ sequential deposition. Less