Self-consistent microwave field and plasma discharge simulations for a moderate pressure hydrogen discharge reactor

A self-consistent two-dimensional model of the electromagnetic field and th e plasma in a hydrogen discharge system has been developed and tested in co mparison to experimental measurements. The reactor studied is a 25 cm diame ter resonant cavity structure operating at 2.45 GHz with a silica belljar o f 10 cm diameter and 17 cm height contained within the microwave cavity. Th e inside of the belljar where the discharge occurs contains a substrate hol der of 5 cm diameter that is used to hold substrates for diamond deposition . The electromagnetic field model solves for the microwave fields using a f inite difference time-domain solution of Maxwell's equations. The plasma mo del is a three energy mode (gas, molecular vibration, and electron) and nin e species (H-2, H, H(n=2), H(n=3), H+, H-2(+), H-3(+), H-, electron) model which accounts for non-Boltzmann electron distribution function and has 35 reactions. Simulated characteristics of the reactor in two dimensions inclu de gas temperature, electron temperature, electron density, atomic hydrogen molar fraction, microwave power absorption, and microwave fields. Comparis ons of the model are made with close agreement to several experimental meas urements including coherent anti-Stokes Raman Spectroscopy measurement of H -2 temperature versus position above the substrate, Doppler broadening opti cal emission spectroscopy (OES) measurements of H temperature versus pressu re, actinometry measurements of the relative H atom concentration, H-alpha OES intensity measurements versus position, and microwave electric field me asurements. The parameter range studied includes pressures of 2500-11 000 P a, microwave powers of 300-2000 W, and three vertical positions of the subs trate holder. (C) 1999 American Institute of Physics. [S0021-8979(99)01213- X].