Investigation of boron penetration through decoupled plasma nitrided gate oxide using backside secondary ion mass spectrometry depth profiling

Abstract

Secondary ion mass spectrometry (SIMS) was used to study boron penetration through different nitrided thin gate oxides. It was found that the reliability of nitrided thin gate oxide requires the nitrogen dose and nitridation process for an effective diffusion barrier to be optimized. As compared to conventional frontside SIMS depth profiling of an activated boron profile in a polysilicon gate stack using 0.5 keV O2 +, the backside depth profile showed a significant improvement in depth resolution and can give a more accurate quantification of boron penetration through the gate oxide. Using the "CsM+" technique, it was shown that nitrogen remains in the oxide layer, and the broadening observed in the nitrogen profiles using conventional SIMs is due to ion beam effects.