Design and optimization of a high-efficiency MPCVD reactor for 4-inch diamond film deposition based on steady-state Multiphysics modeling

Microwave plasma chemical vapor deposition (MPCVD) technique, known for its benefits in low-temperature operations, enhanced growth rates, and superior impurity control, has become a prominent method for manufacturing high-quality diamond films. Nevertheless, current MPCVD reactors continue to face significant challenges, including limited deposition area, inefficient microwave energy utilization, and plasma discharge instability. In response to these challenges, this study firstly introduces a hybrid-mode MPCVD reactor that supports both the TM₀₁ and the TM₀₂ modes based on electromagnetic simulations, in which the electromagnetic mode superposition helps to improve the microwave electric field uniformity above the substrate and allows to increase the substrate diameter up to 110 mm for 4-inch diamond film deposition. Secondly, this study proposes a steady-state Multiphysics model that can simulate pure hydrogen discharges within MPCVD reactors and demonstrate the 4-inch plasma sphere generation of the proposed MPCVD reactor. Finally, the microwave energy efficiency of the proposed MPCVD reactor is further optimized with this Multiphysics model to exceed 94 % without using any additional tuning devices. The 4-inch plasma sphere generation capability and the high microwave energy efficiency enable the optimized MPCVD reactor great potential for practical applications. Besides, the proposed steady-state Multiphysics model of hydrogen discharges can be also used to optimize the geometries and operation conditions other MPCVD reactors.