Simulation and deposition experimental study of a microwave plasma chemical vapor deposition device with an oblique cone structure design

Microwave plasma chemical vapor deposition (MPCVD) equipment features a simple structure, high plasma electromagnetic field intensity, and is pollution-free, making it widely used in the diamond industry. This paper uses the finite element software ANSYS to perform structural design of the resonant cavity of the MPCVD device and optimizes the microwave electric field distribution of the core dimensions of the conical resonant cavity (resonant cavity radius and height) so that the electric field above the deposition platform is ellipsoidal and uniformly distributed. At the same time, a diamond film deposition experiment was conducted to verify the deposition effect of the skewed-conical resonator structure. The results indicate that when the height of the conical resonant cavity is 148 mm and the bottom radius is 116 mm, the electric field strength is 3.926 × 107 V/m, with the electric field in the substrate region more concentrated and stronger at the center. Deposition experiments show that at a deposition temperature of 850 °C, the diamond grain size tends to transform toward a cubic shape, the diamond peaks are sharp, and the residual stress is low, with the film’s indentation crack diameter being 307 μm, revealing its stronger electric field focusing capability and deposition stability.