PLASMA ENHANCED CHEMICAL VAPOR-DEPOSITION MODELING

We are developing a model to simulate the plasma enhanced chemical vapor deposition (PECVD) of thin diamond films. The emphasis to date has been on the development of stand-alone modules to simulate the microwave-induced time-dependent electric and magnetic fields, the generation and energization of plasma electrons in the discharge, the non-equilibrium hydrocarbon chemistry, and the development of a two-dimensional unstructured mesh hydrodynamics solver capable of simulating flow through geometrically realistic reactors. The coupling of the various modules, and the incorporation of a surface chemistry module for the substrate deposition, into a self consistent reactor model is underway. We present some preliminary results from components of a model 2.45 GHz microwave reactor employing H-2 with 1% CH4 and operating at a gas pressure of 5.3 x 10(3) Pa (40 Torr). We have completed an electromagnetic model of the microwave energy deposition in the plasma and calculated the field patterns in the reactor. We have also performed point calculations of the time-dependent electron distribution and of the build-up of atomic hydrogen, the gas temperature, and the resulting generation of CH3, C2H2, and other hydrocarbon radicals. We have also completed a fluid simulation of the flow through the reactor using unstructured mesh techniques. The results we discuss in this paper indicate that careful treatment of non-equilibrium processes in PECVD reactors as well as accurate representation of reactor geometry are essential to a useful simulation capability.