Improving Interface State Density and Thermal Stability of High- \kappa Gate Stack Through High-Vacuum Annealing on Si0.5Ge0.5

We fabricated HfO 2 -based gate stacks on epi-Si 0.5 Ge 0.5 substrates and investigated the effect of thermal treatment on their structural and electrical properties at varying temperatures and pressures in oxygen ambient. The thermal treatment process led to severe degradation of interface quality...

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Bibliographic Details
Published in:IEEE electron device letters 2019-05, Vol.40 (5), p.678-681
Main Authors: Lee, Wei-Li, Yu, Cheng-Yu, Zhang, Jun-Lin, Luo, Guang-Li, Chien, Chao-Hsin
Format: Article
Language:English
Subjects:
Annealing
Hafnium compounds
high-vacuum annealing (HVA)
interface passivation
Logic gates
Oxidation
SiGe channel
Silicon
Silicon germanium
Substrates
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Summary:We fabricated HfO 2 -based gate stacks on epi-Si 0.5 Ge 0.5 substrates and investigated the effect of thermal treatment on their structural and electrical properties at varying temperatures and pressures in oxygen ambient. The thermal treatment process led to severe degradation of interface quality as the temperature increased. Material analyses indicated that annealing in oxygen ambient resulted in oxygen diffusion from the high- {\kappa } material to the SiGe surface, causing undesirable SiGe reoxidation. In high-vacuum annealing, an interface state density of approximately {1.4}\times {10}^{{11}} eV −1 cm −2 and a thermal stability of up to 500 °C were achieved for the gate stack on SiGe.
ISSN:0741-3106
1558-0563
DOI:10.1109/LED.2019.2905139