Dependence of electrical properties of HfSiON gate dielectrics on TaSiN metal electrode thickness

Abstract

We have studied the effect of tantalum–silicon–nitride (TaSiN) metal electrode thickness on the electrical properties of ultrathin HfSiON gate dielectrics formed by atomic layer deposition (ALD) technology using Hf(N(CH3)(C2H5))4 and SiH(N(CH3)2)3 precursors. The TaSiN/HfSiON gate stacks were intended for use in conventional metal gate transistors with a high temperature thermal budget of 950 °C. Leakage current, effective mobility and the drain current in 30 nm thick TaSiN gate electrodes were improved with respect to the values for 10 nm thick TaSiN gate electrodes. From back-side secondary ion mass spectrometry (SIMS) analyses, it was concluded that thick TaSiN gate electrodes suppressed the nitrogen diffusion from the SiN hard mask into HfSiON/SiON gate stacks during activation annealing.