AVS 51st International Symposium
    Dielectrics Monday Sessions
       Session DI-MoP

Paper DI-MoP2
Orientation Selective Epitaxy of CeO@sub 2@ Thin Films on Si(100) Substrates by Magnetron Reactive Sputtering Enhanced by Oxygen Radical Beams with Substrate Bias

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: T. Inoue, Iwaki Meisei University, Japan
Authors: T. Inoue, Iwaki Meisei University, Japan
M.O. Ohashi, Iwaki Meisei University, Japan
N. Sakamoto, Iwaki Meisei University, Japan
S. Shida, Iwaki Meisei University, Japan
T.W. Chiu, University of Tsukuba, Japan
K. Yamabe, University of Tsukuba, Japan
Correspondent: Click to Email
It is found that the epitaxial CeO@sub 2@(100) and CeO@sub 2@(110) layers are able to be selectively grown using reactive dc magnetron sputtering enhanced with an inductively coupled rf plasma (helicon sputtering) by controlling substrate bias and plasma power.@footnote 2@ Although many reports have been made on the growth of CeO@sub2@(110)/Si(100), recently CeO@sub 2@(100) layers have been reported to grow on atomically cleaned Si(100) surfaces with a 2x1 reconstructed structure in an ultra-high vacuum. Our method has superiority in the requirement of only practical H-terminated surfaces obtained by the usual wet cleaning process. Adopting 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, the CeO@sub 2@(100) layer epitaxy is attained applying adequate substrate bias whereas CeO@sub 2@(110) layers are grown without substrate bias. Helicon sputtering is performed at rf power of 50 W for helicon chathode coil, 120 W for helicon chathode dc plasma power and substrate bias ranging between -20 and +50 V. 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. 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, beyond which (110) layer grow. Precise mapping of growth paramters, 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 improve crystalline quality and to lower the epitaxial temperature, we have started to develop a novel reactive sputtering method employing oxygen free radical beams. The oxygen radical source is operated typically under the conditions; applied rf power of 50 W and O@sub 2@ gas flow of 1 sccm, whereas the intensity of free radical beams is varied controlling rf power and oxygen gas flow. We demonstrate the experimentsl results indicating its effectiveness; successful epitaxial temperature lowering and crystalline quality improvements. Chracterization of the epitaxial films are carried out using RHEED, 4-circle XRD, XTEM and AFM, including C/V and I/V measurements for getting fundamental electrical properties. This orientation selective epitaxial growth technology will be useful for device applications. @FootnoteText@ @footnote 1@ Present address: ULVAC-PHI Corp., 370 Enzou, Chigasaki 253-0084, Japan@footnote 2@ T. Inoue et al., J. Vac. Sci. Tehcnol. A 22(1), 46 (2004).