Simulation of diamond synthesis by microwave plasma chemical vapor deposition with multiple substrates in a substrate holder

To simulate the electric field distribution in a cylindrical resonant cavity during diamond crystal growth by microwave plasma chemical vapor deposition (MPCVD), a three-dimensional (3D) model, based on the electromagnetic field part of the finite element simulation solver COMSOL Multiphysics software, was established in this study. It was found that precise fillet treatment for the edge of the sample holder in the cavity can effectively improve the distribution of the electric field in this area, which is more conducive for the epitaxial growth of diamond. Based on the actual experimental requirements, nine diamond substrates were added to the holder with a previously processed edge fillet. By comparing with the simulated situation without substrates, it was proved that the addition of substrates influences the electric field distribution nearby. Furthermore, a new groove substrate holder with rounded corners was designed. Nine substrates with specific spacing were added to the groove holder, and the 3D and two-dimensional electric field distribution in this region were obtained. The optimized substrate holder makes the substrates less exposed to strong microwave plasma, which aids in high-quality single-crystal diamond synthesis. The simulation results were further verified experimentally.