Optimization Design of MPCVD Single Crystal Diamond Growth Based on Plasma Diagnostics

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/cm(3)) 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 mu m/h). By this method system, effective plasma control and process optimization can be carried out meeting for different single crystal diamond growth.