Alternative interpretation of plasma processing damage data to facilitate comparisons between oxide etchers

Plasma processing damages devices by driving current through the thin gate oxides. During contact and via oxide etching processes, direct electrical contact between the plasma and the device junctions is made only during the overetch period when the thick oxide layer is removed. Anecdotal evidence indicates that high-plasma density oxide etchers cause more device damage than do low or medium density reactors. We need to understand whether the processing damage is an unavoidable consequence of the high plasma density or merely due to a relatively immature reactor design that has not yet been optimized to minimize damage. This paper examines correlations between device damage and oxide etching parameters including the total bias current, the oxide etching rate, and the DC self-bias voltage on the bias electrode, V_dc. We estimate the bias current through a combination of easily accessible plasma reactor power parameters, namely the source and bias power levels and V_dc, and we motivate this approximation by exploring a universal curve for V_dc