Quantitative evaluation of plasma-damaged SiN/Si structures using bias-dependent admittance analysis

Abstract

Plasma process-induced damage (PID) to SiN dielectric films was investigated by using an impedance (admittance)-based technique. Multi-layered equivalent circuits were introduced to assign the spatial and energy distribution of defects created in the SiN/Si system. We propose to use admittance as the principal parameter for damaged SiN/Si systems after Ar and He plasma exposures. The change in the border trap density was determined from the admittance in accumulation, whereas the interface state density and energy profile that was created was determined from the admittance in depletion. Plasma source-dependent damage-creation mechanisms are discussed. It was found that the extracted border trap density in the He plasma-damaged sample was larger than that in the Ar plasma-damaged sample under the same ion dosage. The proposed characterization scheme is useful for assessing PID to dielectric/Si systems.