AVS 52nd International Symposium
    Surface Science Tuesday Sessions
       Session SS-TuP

Paper SS-TuP21
Substrate-Bias-Dependent Orientation-Selective-Epitaxial Growth of CeO@sub 2@ Thin Films on Si(100) Substrates by Magnetron Reactive Sputtering

Tuesday, November 1, 2005, 4:00 pm, Room Exhibit Hall C&D

Session: Surface Science Poster Session
Presenter: T. Inoue, Iwaki Meisei University, Japan
Authors: T. Inoue, Iwaki Meisei University, Japan
D. Kukuruznyak, National Institute for Materials Science, Japan
T. Chikyo, National Institute for Materials Science, Japan
K. Kato, Fukushima Technology Centre, Japan
Correspondent: Click to Email
Although many reports have been made on the growth of CeO@sub2@(110)/Si(100), orientation selective epitaxial (OSE) growth of CeO@sub 2@(100) and CeO@sub 2@(110) layers is found to be capable by controlling substrate bias and plasma power in reactive dc magnetron sputtering enhanced with an inductively coupled rf plasma.@footnote 1@ We adopted two step growth method; ultrathin metallic Ce layer deposition at room temperature using Ce metal target followed by silicidation process at several hundreds degree C, and subsequent reactive sputtering in an Ar/O@sub 2@ mixture environment at elevated temperature. Reactive magnetron sputtering is performed at rf power of 50 W for induction coil and 120 W for cathode dc plasma power under substrate bias ranging between -25 and +25 V varied by 5~V step. Growth rate is controlled in between 0.2 and 0.4 nm/s varying Ar gas flow between 4 and 15 sccm. Oxygen gas flow for reactive sputtering is 1 sccm. CeO@sub2@(100) layers grow under substrate bias around both +15 and -15 V with a width of approximately 10 V, otherwise CeO@sub2@(110) layers grow. The orientation selection is found to be also dependent on plasma power, in other words the growth rate: upper limit in growth rate exists for (100) layer growth, above which (110) layer grow. Precise mapping of growth parameters for OSE, in terms of substrate bias and growth rate, for the growth of CeO@sub 2@(100) films are attained from a lot of growth experiments. In order to get insight into orientation selectivity depending on substrate bias, we are making systematic experiments to study orientation component changes with substrate bias in CeO@sub 2@ layers, which leads to a clue for understanding the relation between orientation of nuclei and substrate bias. We also demonstrate the experimental results indicating effectiveness of assistance by oxygen radical beams on reactive sputtering; successful epitaxial temperature lowering and crystalline quality improvements. Characterization of the epitaxial films are carried out using RHEED, XRD, XTEM and AFM. This orientation selective epitaxial growth (OSE) technology will be useful for sophisticated structure using multiple layer epitaxy. @FootnoteText@ @footnote 1@ T. Inoue et al., J. Vac. Sci. Tehcnol. A 22(1), 46 (2004).