Oxygen migration in TiO{sub 2}-based higher-k gate stacks

Journal Article · Mon Mar 15 04:00:00 EDT 2010 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3298454· OSTI ID:21476387

Kim, Sang Bum; Brown, Stephen L; Rossnagel, Stephen M; Bruley, John; Copel, Matthew; Hopstaken, Marco J. P.; Narayanan, Vijay; Frank, Martin M ^[1]

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1. IBM T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, New York 10598 (United States)

We report on the stability of high-permittivity (high-k) TiO{sub 2} films incorporated in metal-oxide-silicon capacitor structures with a TiN metal gate electrode, focusing on oxygen migration. Titanium oxide films are deposited by either Ti sputtering [physical vapor deposition (PVD)] followed by radical shower oxidation or by plasma-enhanced atomic layer deposition (PEALD) from titanium isopropoxide (Ti{l_brace}OCH(CH{sub 3}){sub 2{r_brace}4}) and O{sub 2} plasma. Both PVD and PEALD films result in near-stoichiometric TiO{sub 2} prior to high-temperature annealing. We find that dopant activation anneals of TiO{sub 2}-containing gate stacks at 1000 deg. C cause 5 A or more of additional SiO{sub 2} to be formed at the gate-dielectric/Si-channel interface. Furthermore, we demonstrate for the first time that oxygen released from TiO{sub 2} diffuses through the TiN gate electrode and oxidizes the poly-Si contact. The thickness of this upper SiO{sub 2} layer continues to increase with increasing TiO{sub 2} thickness, while the thickness of the regrown SiO{sub 2} at the gate-dielectric/Si interface saturates. The upper SiO{sub 2} layer degrades gate stack capacitance, and simultaneously the oxygen-deficient TiO{sub x} becomes a poor insulator. In an attempt to mitigate O loss from the TiO{sub 2}, top and bottom Al{sub 2}O{sub 3} layers are added to the TiO{sub 2} gate dielectric as oxygen barriers. However, they are found to be ineffective, due to Al{sub 2}O{sub 3}-TiO{sub 2} interdiffusion during activation annealing. Bottom HfO{sub 2}/Si{sub 3}N{sub 4} interlayers are found to serve as more effective oxygen barriers, reducing, though not preventing, oxygen downdiffusion.

• OSTI ID: 21476387
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 5 Vol. 107; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
ANNEALING
CAPACITANCE
CHALCOGENIDES
CHEMICAL COATING
CHEMICAL VAPOR DEPOSITION
DEPOSITION
DIELECTRIC MATERIALS
DIELECTRIC PROPERTIES
DIFFUSION
ELECTRICAL PROPERTIES
ELEMENTS
FILMS
HAFNIUM COMPOUNDS
HAFNIUM OXIDES
HEAT TREATMENTS
INTERFACES
LAYERS
MATERIALS
NITRIDES
NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PERMITTIVITY
PHYSICAL PROPERTIES
PHYSICAL VAPOR DEPOSITION
PLASMA
PNICTIDES
REFRACTORY METAL COMPOUNDS
SEMICONDUCTOR MATERIALS
SEMIMETALS
SILICON
SILICON COMPOUNDS
SILICON NITRIDES
SILICON OXIDES
SPUTTERING
SURFACE COATING
THIN FILMS
TITANIUM COMPOUNDS
TITANIUM NITRIDES
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS