高气压微波等离子体中电场的测量与调控及其对单晶金刚石生长的影响

Single crystal diamond is considered as a promising material for optical element, high frequency and high power electronic devices, due to its outstanding physical and chemical properties. Now, the improvement of growth rate, crystalline quality and film uniformity of CVD single crystal diamond are the urgent problems need to be solved. In this project, high-pressure (20~100kPa) microwave plasma source will be design and implementation based on squeezable waveguide and special electrode structure. By measuring and regulating the electric field in microwave plasma, the effects of electric field on the CVD single crystal diamond are investigated. The effects of reactor structure, plasma parameter and sheath of plasma on the distribution of electric field in the plasma will be studied by simulation.The effects of reactor structure, working gases and the concentration distribution of particles in the plasma on the uniformity of plasma will be experimental studied. The electric field in the microwave plasma will be measured using the Stark effect of Hγand Hδ. The electric field distribution in microwave plasma is further regulated and controlled by changing reactor structure and growth parameter. The impacts of the electric field distribution on the growth rate, crystalline quality and film uniformity of CVD single crystal diamond are investigated. The defects forming mechanism of single crystal diamond is also explored. The coordination optimization of reactor structure and growth parameter is built up to improve the crystalline quality of CVD single crystal diamond.

单晶金刚石具有优异的物理化学性能，在制造光学元件、高频高功率电子器件等领域具有潜在的应用价值。提高CVD单晶金刚石的沉积速率、晶体质量和均匀性是目前迫切需要解决的问题。本项目拟基于压缩波导和特殊的棒-板电极结构，设计高气压（20~100kPa）微波辉光等离子体源；通过对等离子体中电场的测量与调控，研究电场对CVD单晶金刚石沉积的影响机理。通过模拟计算研究反应腔结构、等离子体参数、等离子体鞘层对等离子体中电场分布的影响，实验研究反应腔结构、工作气体组分、等离子体基团浓度与分布对等离子体均匀性的影响，建立利用Hγ、Hδ谱线的Stark展宽测量高气压含氢微波辉光等离子体中电场的方法。进一步通过改变反应腔结构和生长参数对等离子体中的电场分布进行调控，研究电场分布对单晶金刚石的沉积速率、晶体质量和均匀性的影响，探索单晶金刚石的缺陷产生机制，建立反应腔结构和生长参数的优化协同。

项目研究中首先设计了具有压缩波导和双基片结构的微波等离子体反应腔，并对反应腔结构进行了模拟计算优化，得到了较宽运行气压（0.5-40kPa）微波等离子体化学气相沉积装置，并在较优的沉积气压下开展单晶金刚石的生长研究。通过模拟计算研究了反应腔结构、等离子体参数对等离子体中电场分布的影响。实验研究了反应腔结构、工作气体组分、衬底温度、沉积气压对等离子体中基团的谱线强度和均匀性的影响。进一步通过调整反应腔结构和沉积参数对等离子体中的电场分布进行调控，研究电场分布对单晶金刚石的沉积速率、晶体质量和均匀性的影响，探索研究了单晶金刚石的缺陷产生机制。通过改变单晶金刚石种晶的边缘形状及样品台与种晶的位置关系和等离子体运行条件，对种晶边缘电场进行调控，研究电场对种晶边缘金刚石生长的影响机理。通过有效调控，单晶金刚石在同质外延生长过程中向四周的扩大生长也呈单晶生长模式。通过项目研究，建立起反应腔结构和生长参数的优化协同，得到了一套小功率（1kW)、高沉积气压（≥20kPa）、高沉积速率（≥20μm/h）、双基片结构、大尺寸单晶生长（9mm*9mm）、具有完全自主知识产权的微波等离子体设备及高质量单晶金刚石生长工艺，实现了单晶金刚石的有效二维扩大生长。