X-ray photoelectron spectroscopy study of high-k CeO{sub 2}/La{sub 2}O{sub 3} stacked dielectrics

Journal Article · Sat Nov 15 00:00:00 EST 2014 · AIP Advances

DOI:https://doi.org/10.1063/1.4902017· OSTI ID:22420159

Zhang, Jieqiong ^[1]; Wong, Hei ^[1]; Yu, Danqun ^[2]; Kakushima, Kuniyuki; Iwai, Hiroshi ^[3]

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1. Department of Electronic Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)
2. Department of Information Sciences and Electronic Engineering, Zhejiang University, Hangzhou (China)
3. 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

Related Subjects

36 MATERIALS SCIENCE
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