Thin-oxide charging damage to microelectronic test structures in an electron-cyclotron-resonance plasma

Abstract

Processing yields in electron-cyclotron-resonance (ECR) and other high-density plasma sources will be increasingly limited by plasma-induced damage. This work investigates the effects of plasma nonuniformities on charging damage to polysilicon-gate MOS capacitor test structures exposed to O2 ECR plasmas. The nonuniformities were produced by independently biasing electrodes located above the wafer. The damage was characterized with ramp-voltage breakdown measurements. Comparison of calculated profiles of the potential difference across the gate-oxide layers of the MOS capacitors with whole wafer maps of the breakdown voltage measurements shows that maximum damage occurs where the oxide potential difference is largest but only in the presence of plasma nonuniformities.