Plasma-induced charging damage to MOS capacitor structures in electron-cyclotron-resonance plasmas

Abstract

Summary form only given. As critical device dimensions shrink and gate-oxide thicknesses decrease, ULSI yields after processing in electron-cyclotron-resonance (ECR) and other high-density sources will be increasingly limited by plasma-induced damage. The purpose of this work is to investigate the effects of plasma parameter variations on charging damage to polysilicon-gate MOS capacitor test structures upon exposure to O/sub 2/ ECR plasmas. The test structures are designed as antennas with a gate-oxide thickness of 10 nm antenna ratios of from 16 to 11,111. An electrode assembly, consisting of both a ring and a grid electrode, was mounted in the ECR system directly over the wafer stage. The radial plasma uniformity above the surface of the wafer was then varied by independently biasing the ring and grid electrodes relative to the chamber ground. The effect of this variation on the radial plasma profile was characterized with Langmuir and emissive probes. Test wafers containing the MOS capacitor antenna structures were then exposed to the ECR plasma under varying plasma-uniformity conditions, and the damage was subsequently characterized with ramp-voltage breakdown measurements. The degree of plasma-induced damage in the MOS capacitor test structures was found to correlate with the degree of, non-uniformity in the radial plasma potential.