Monte Carlo simulation of electron behavior in an electron cyclotron resonance discharge

Electron behavior in an electron cyclotron resonance microwave discharge maintained by the TM₀₁ mode fields of a cylindrical waveguide has been investigated via a Monte Carlo simulation. Since this discharge has high degree of ionization (≥1%), a self-consistent simulation of the plasma dynamics is achieved through the use of the ponderomotive and grad B (-μ∇_∥B) forces. Accumulation of negative charges on the boundary surface sets up a sheath whose influence is also taken into account. The time averaged, spatially dependent electron energy distribution (EED) is computed self-consistently by integrating electron trajectories subjected to the microwave fields, the divergent background magnetic field, the space charge field, and the sheath field, and taking into account electron-electron collisions and collisions with the neutral hydrogen atoms. The EED is characterized by two electron temperatures with the population of the tail increasing for decreasing pressure. At low pressures (∼0.5 mTorr), the sheath potential is on the order of 100 V and decreases with increasing pressure. This observation suggests a pressure range for operation of reactors for diamondlike carbon film deposition.