Influence of La on the electrical properties of HfSiON: From diffusion to Vth shifts

•TiN/HfSiON/SiO2/Substrate stacks were investigated with C–V measurements and SIMS.•No linear relationship of the threshold voltage on the La concentration at the HfSiON/SiO2 was found.•A linear relationship of the threshold voltage on the La sheet concentration in the HfSiON was found.•Crystallizat...

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Bibliographic Details
Published in:Microelectronic engineering 2013-09, Vol.109, p.200-203
Main Authors: Hackenberg, M., Pichler, P., Baudot, S., Essa, Z., Gro-Jean, M., Tavernier, C., Schamm-Chardon, S.
Format: Article
Language:English
Subjects:
Annealing
Condensed Matter
Correlation
Diffusion
Electrical properties
Engineering Sciences
Hafnium oxide
HfSiON
High-k dielectric
La diffusion
Materials Science
Micro and nanotechnologies
Microelectronics
Phase separation
Physics
Silicon dioxide
Stacks
Threshold voltage tuning
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Summary:•TiN/HfSiON/SiO2/Substrate stacks were investigated with C–V measurements and SIMS.•No linear relationship of the threshold voltage on the La concentration at the HfSiON/SiO2 was found.•A linear relationship of the threshold voltage on the La sheet concentration in the HfSiON was found.•Crystallization of the HfSiON is proposed as explanation of the experimental findings. We investigated the dependence of the electrical properties of TiN/La2O3/HfSiON/SiO2/Si-substrate stacks with 15nm thick HfSiON layers on annealing temperature and time. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and capacitance–voltage (C–V) measurements were used to characterize the La depth profiles and the electrical properties. We found that the threshold voltage (Vth) shift after annealing correlates linearly with the total amount of La diffused into the HfSiON rather than with the La concentration at the HfSiON/SiO2 interface. This unexpected behavior can be explained by the decreased thermal stability of thick (>2nm) HfSiON layers which probably leads to phase separation during annealing and therefore to HfO2/SiO2 interfaces all over the stack.
ISSN:0167-9317
1873-5568
DOI:10.1016/j.mee.2013.03.071