Steady-state rf magnetron discharges

Abstract

A study of the steady-state discharges and the spatial distributions of plasma parameters vertical to the magnetic field was made in an rf magnetron with oval cross section. Langmuir probes were used for the major diagnostics. The device generates low-ion energy, high-ion flux stable plasma (Ei∼102 eV, Γi∼5 mA/cm2 at 1 W/cm2 rf power). Ion transport toward the positive sheath is enhanced by the rf induced dc electric field in the uniform glow. The state of the glow is independent of rf power except ion density ni∝ (rf power)α. The voltage drop across the sheath follows V∝(rf power) β with 0<α<β<1. The discharge strongly depends on magnetic field strength and system pressure, and weakly depends on the gas chemistry. Generally, the state of the discharge is determined by charged particle generation, transport and loss processes, and in turn controlled by the system operating parameters. The experimental results obey the conservation laws and the steady-state criterion. The correlations between plasma parameters and system parameters are investigated and discussed.