微波等离子体化学气相沉积(Microwave plasma chemical vapor deposition, MPCVD)技术是制备大尺寸、高品质单晶金刚石的理想途径, 然而MPCVD单晶金刚石生长过程的复杂性与晶体生长需求的多样性难以对生长过程进行优化设计。针对此问题, 本研究提出了一种基于等离子体诊断技术的MPCVD单晶金刚石生长的系统性设计方法, 采用等离子体成像和光谱分析对微波等离子体进行量化诊断。并利用自主研发的MPCVD设备, 研究了腔室压力-微波功率-等离子体性状-衬底温度间的物理耦合特性和量化关系, 得到了不同参数下的等离子体有效长轴尺寸、基团浓度和分布、能量密度等数据, 以实验观测数据为基础拟合得到了单晶金刚石生长工艺图谱。根据此工艺图谱, 可以通过选择生长温度和所需生长面积来选取工艺参数, 且通过实验验证, 表明此图谱具有较强的指导意义, 预测参数误差小于5%。同时根据该图谱的预测, 研究了不同等离子体能量密度下的单晶金刚石生长情况, 在较低功率下(2600 W)也得到了较高的能量密度(148.5 W/cm³), 含碳前驱体的浓度也高于其他工艺条件, 因而获得了较高的生长速率(8.9 μm/h)。此套方法体系可以针对不同单晶金刚石生长需求进行有效的等离子体调控和工艺优化。

Microwave plasma chemical vapor deposition (MPCVD) technology is an ideal way to prepare large size and high-quality single crystal diamonds. However, the complexity of MPCVD single crystal diamond growth and the diversity of crystal growth requirements make it difficult to optimize the growth process. To address this issue, a systematic design method for MPCVD single crystal diamond growth based on plasma diagnostic technology was proposed, using plasma imaging and spectral analysis to quantitatively diagnose microwave plasma. The physical coupling characteristics and quantitative relationship between pressure, microwave(MW) power, plasma properties, and substrate temperature were studied by using home-made MPCVD system. And the size of major axis, precursor group concentration and distribution, energy density, and other data of the plasma under different parameters were obtained. Based on experimental data, the growth process map of single crystal diamond was obtained. According to this map, we selected process parameters by growth temperature and growth area. Through experimental verification, it is shown that this map is usful for guiding prediction with parameter error of less than 5%. Simultaneously, based on the predicted map, growth of single crystal diamond under different plasma energy densitiesis studied. At lower power (2600 W), a higher energy density (148.5 W/cm³) was obtained, and the concentration of carbon containing precursors was higher than that of the other parameters, resulting in a higher growth rate (8.9 μm/h). By this method system, effective plasma control and process optimization can be carried out meeting for different single crystal diamond growth.