Simulation and development of optimized microwave plasma reactors for diamond deposition

A computer program has been developed for the design and optimization of microwave plasma reactors used for the chemical vapour deposition (CVD) of diamond. The computer code consists of program modules for the calculation of electromagnetic field and plasma density distributions. The reliability of the simulation has been tested by modelling the reactor performance of the widely used cylindrical TM01 reactors, which show plasma instabilities at increased microwave power levels. An additional module is used for automatic optimization of the reactor performance. Based on the simulation program, a novel microwave plasma reactor employing an ellipsoidal cavity has been developed. This reactor has been realized and tested experimentally for microwave frequencies of 2.45 GHz and 915 MHz. The performance confirms the simulation results perfectly. Due to the plasma stability, these novel reactors are suitable for the growth of thick diamond layers with demonstrated areas up to 15 cm in diameter.