A model and experiments for thin oxide damage from wafer charging in magnetron plasmas

Abstract

A physically based model that has been developed to explain the role of plasma nonuniformity in charge damage to oxides is presented. For a uniform plasma the local conduction currents to the water surface integrate to zero over the RF period, and the surface charging is sufficient to damage oxides. For the case of thin oxides under a gate exposed to a nonuniform magnetron plasma, the gate surface can charge up until the oxide tunneling current balances the difference in the mean local conduction currents from the plasma. It is this oxide current that leads to degradation. The oxide current obtained via SPICE circuit simulations, probe measurements and breakdown measurements shows good agreement with experimental damage data of 'antenna' capacitors.