Influence of the excitation frequency on CH4/H/H-2 plasmas for diamond film deposition: electron energy distribution function and atomic hydrogen concentration

The influence of the excitation frequency f = omega /2 pi of the applied el ectric field on the period average electron energy distribution function (E EDF) and on the atomic hydrogen concentration found near the deposited diam ond films (substrate) and in the bulk of CH4(less than or equal to5%)/H/H-2 plasmas produced in RF and MW discharges is estimated. This is done throug h the solution, as a function of the reduced effective electric field, of a stationary homogeneous electron Boltzmann equation (EBE and the solution, in terms of the atomic hydrogen mole fraction, of a simple kinetic model fo r the plasma mechanisms underlying the production and loss of atomic hydrog en. The physical basics underlying the approach followed to solve the EBE, including discussion of EEDF time-modulation effects, are discussed in the light of recent results by Loureiro (1993 Phys. Rev. 47 1262) on time-depen dent kinetics of pure Hz plasmas. Correlations are established between the results, obtained under various discharge conditions, from plasma-enhanced chemical vapour deposition (PECVD) experiments of diamond-like cat bun (DLC ) and diamond thin films, and the calculated EEDF, atomic hydrogen concentr ations tin the plasma and near the substrate) and mechanisms underlying the production and loss of atomic hydrogen in the plasma.