Design and Simulation of a Microwave Plasma Enhanced Chemical Vapor Deposition System Using Multiphysics Fluid Modeling

One of the promising thin film plasma based manufacturing methods for the growth of diamonds is microwave plasma enhanced chemical vapor deposition (MPECVD) is different from other plasmas where the microwave frequency can oscillate electrons which leads to the collision of electrons with gaseous atoms and molecules generating a high degree of ionization. By applying a microwave the plasma in the MPECVD system can be ignited and sustained, where a thin film is deposited at lower temperatures. This paper discusses the design of a 3-D MPECVD chamber operated at a 2.45 GHz of frequency using the multiphysics fluid modelling based on a finite element method (FEM) that incorporates many physical interfaces including laminar flow, heat transfer in fluids, plasma, and electromagnetic waves to give more self-consistent and accurate simulation results. The plasma discharge is modelled by coupling drift-diffusion, heavy species transport, and electric fields into a single multiphysics model. The conservations of mass and momentum are modelled in simulation by solving continuity and Navier-strokes equation, respectively. The geometrical design of MPECVD consists of a coaxial waveguide connected by slots to a cylindrical plasma chamber at the center to produce $\text{TM}_{011}$ mode. With an input power of 1 kW and 0.6 kW at WR340 coaxial waveguide input port at 2.45 GHz and argon pressure at 1 atm, the plasma density increases from $1.51\mathrm{e}17$ to $4.51\mathrm{e}171/\mathrm{m}^{3}$ reaching steady-state at around 5 msec and an argon plasma are excited by the TM 011 cavity resonance. Detailed analysis of the MPECVD operation over the critical operating density of the driving frequency and the relation between input powers to the waveguide and deposited power to the chamber will be presented and discussed.