微波等离子体化学气相沉积(MPCVD)法产生的等离子体密度高，材料外延生长过程可控性好且洁净度高，是制备高质量金刚石膜的重要方法。基于谐振腔理论和三维全波电磁场仿真，对MPCVD设备微波系统中谐振腔、模式转换器、样品托等影响微波传输效率及电场分布形态的部件进行设计和优化，并通过对微波传输系统关键参量的测试和监控，研究系统调试变量对金刚石外延生长的影响。基于自研的MPCVD设备，实现较高品质金刚石膜的合成，金刚石有效生长区域为50 mm圆面，外延生长速度10~25 μm/h，单晶样品的表征结果显示合成的金刚石透光率接近理论值，材料的结晶程度良好，氮、硅等杂质含量较低。

Microwave plasma chemical vapor deposition (MPCVD) is an important method for synthesis of high-quality diamond film due to its high plasma density, good controllability and high cleanliness in the deposition process. Based on the theory of resonant cavity and three-dimensional full-wave electromagnetic field simulation, the microwave plasma cavity, mode converter and substrate holder shapes, which have a great influence on microwave coupling efficiency and electric field distribution, were designed and optimized. By testing and monitoring the key parameters in the microwave transmission system, influence of the tuning variables on diamond deposition were analyzed. With the MPCVD device proposed in this paper, high quality diamond films were deposited with an effective circular growth area with a diameter of 50 mm at a growth rate of 10 μm/h to 25 μm/h. The characterization results show that the single crystal diamond films have optical transmittance close to theoretical threshold and an excellent crystalline structure, with low impurity contents of nitrogen and silicon.