MODELING OF MAGNETRON ETCHING DISCHARGES

Magnetron discharges are currently used in etching silicon, GaAs, and other semiconductor materials since they provide high etch rates and reduced ion bombardment damage to the wafers. A discharge physics model is presented for a 13.56 MHz planar magnetron discharge. The applied magnetic field is uniform and normal to the direction of the electric field. The model consists of the first three moments of the Boltzmann transport equation with appropriate description of elastic and inelastic collision terms. Numerical solutions have been obtained for a chlorine discharge. The study includes a parametric variation of applied bias and magnetic field. The electron density scales linearly with power and modified pressure P[1 + (omega(c)/nu)2]1/2, where omega(c) is electron cyclotron frequency and v is elastic collision frequency. The magnetic field lowers the plasma potential, and the potential drop in the glow also becomes significant. In addition, the phase lead of discharge current over the voltage decreases substantially as the magnetic field is increased.