Detrimental Hf penetration into TiN gate electrode and subsequent degradation in dielectric properties of HfSiO high- k film

• Published in: Applied physics letters Vol. 99; no. 14; pp. 142907 - 142907-3
• Main Authors: Arimura, Hiroaki, Odake, Yuki, Kitano, Naomu, Hosoi, Takuji, Shimura, Takayoshi, Watanabe, Heiji
• Format: Journal Article
• Language: English
• Published: American Institute of Physics 03-10-2011
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.3646378

Hafnium penetration through the TiN gate electrode as thick as 10nm is detected in the TiN/HfSiO/SiO
2
gate stacks after high-temperature annealing by using x-ray photoelectron spectroscopy. The Hf outdiffusion, showing TiN thickness dependence, is revealed to cause permittivity lowering of the pristine HfSiO high-
k
layer, which accelerates the equivalent oxide thickness increase and degrades the dielectric properties. In contrast, such diffusion is suppressed by adopting metal inserted polycrystalline silicon stack (MIPS) structure. Our further experiments indicate that the SiO
2
regrowth during high-temperature annealing, which is hampered in MIPS structure, triggers the adverse Hf diffusion.