Nitriding process for next-generation semiconductor devices by VHF (162 MHz) multi-tile push-pull plasma source

Abstract

For the low power and high-performance semiconductor devices, a silicon oxynitride (SiOxNy) layer is required as the gate sidewall spacer material by replacing oxygen of the silicon oxide (SiO2) sidewall layer with nitrogen through a plasma nitriding process. In this study, as a plasma nitriding process, instead of conventional radio frequency plasma nitriding utilizing high frequency (HF; 13.56 MHz, etc.) plasmas, a very high frequency (VHF) plasma operated at 162 MHz with a multi-tile push-pull plasma source has been used in nitriding the SiO2 layer at room temperature and the effects of the VHF (162 MHz) plasma on SiOxNy formation from a SiO2 layer and electrical characteristics of the SiOxNy formed by the plasma nitridation were investigated. The use of the VHF (162 MHz) multi-tile push-pull plasma formed ∼10 nm thick SiOxNy with a very high nitrogen percentage of ∼24% on the SiO2 layer surface. Also, when the surface roughness of the SiOxNy and electrical characteristic of MOS capacitors fabricated with the SiOxNy formed by the VHF (162 MHz) plasma were compared with those formed by a capacitively coupled plasma at 60 MHz, a lower surface roughness and much lower leakage current of MOS capacitor could be obtained.