Evaluation and modeling of lanthanum diffusion in TiN/La_2O_3/HfSiON/SiO_2/Si high-k stacks

摘要

In this study, TiN/La_2O_3/HfSiON/SiO_2/Si gate stacks with thick high-k (HK) and thick pedestal oxide were used. Samples were annealed at different temperatures and times in order to characterize in detail the interaction mechanisms between La and the gate stack layers. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) measurements performed on these samples show a time diffusion saturation of La in the high-k insulator, indicating an La front immobilization due to LaSiO formation at the high-k/interfacial layer. Based on the SIMS data, a technology computer aided design (TCAD) diffusion model including La time diffusion saturation effect was developed.