X-ray photoelectron spectroscopy study of high-k CeO{sub 2}/La{sub 2}O{sub 3} stacked dielectrics
- Department of Electronic Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)
- Department of Information Sciences and Electronic Engineering, Zhejiang University, Hangzhou (China)
- Frontier Research Center, Tokyo Institute of Technology, Nagatsuta-cho, Yokohama, 226-8502 (Japan)
This work presents a detailed study on the chemical composition and bond structures of CeO{sub 2}/La{sub 2}O{sub 3} stacked gate dielectrics based on x-ray photoelectron spectroscopy (XPS) measurements at different depths. The chemical bonding structures in the interfacial layers were revealed by Gaussian decompositions of Ce 3d, La 3d, Si 2s, and O 1s photoemission spectra at different depths. We found that La atoms can diffuse into the CeO{sub 2} layer and a cerium-lanthanum complex oxide was formed in between the CeO{sub 2} and La{sub 2}O{sub 3} films. Ce{sup 3+} and Ce{sup 4+} states always coexist in the as-deposited CeO{sub 2} film. Quantitative analyses were also conducted. The amount of CeO{sub 2} phase decreases by about 8% as approaching the CeO{sub 2}/La{sub 2}O{sub 3} interface. In addition, as compared with the single layer La{sub 2}O{sub 3} sample, the CeO{sub 2}/La{sub 2}O{sub 3} stack exhibits a larger extent of silicon oxidation at the La{sub 2}O{sub 3}/Si interface. For the CeO{sub 2}/La{sub 2}O{sub 3} gate stack, the out-diffused lanthanum atoms can promote the reduction of CeO{sub 2} which produce more atomic oxygen. This result confirms the significant improvement of electrical properties of CeO{sub 2}/La{sub 2}O{sub 3} gated devices as the excess oxygen would help to reduce the oxygen vacancies in the film and would suppress the formation of interfacial La-silicide also.
- OSTI ID:
- 22420159
- Journal Information:
- AIP Advances, Vol. 4, Issue 11; Other Information: (c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 2158-3226
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CERIUM
CERIUM IONS
CERIUM OXIDES
CHEMICAL BONDS
CHEMICAL COMPOSITION
COMPARATIVE EVALUATIONS
DECOMPOSITION
DEPOSITS
ELECTRICAL PROPERTIES
FILMS
INTERFACES
LANTHANUM
LANTHANUM COMPLEXES
LANTHANUM OXIDES
OXIDATION
OXYGEN
PHOTOEMISSION
SILICIDES
SILICON
X-RAY PHOTOELECTRON SPECTROSCOPY