Orientation and Electrical Resistivity of Aluminum Oxide Films Prepared by Ion Beam Assisted Plasma Cvd
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ABSTRACT Aluminum oxide (A12 0 3 ) films were prepared on a nickel based superalloy (Inconel 718) by ion beam assisted plasma CVD at the multiple incident angles of the ion beams to a substrate. Crystal structure of these films was analyzed by X-ray diffraction (XRD). Electrical resistance of the films was measured at temperatures ranging from room temperature to 8501C. The incident angle of the ion beams influenced the orientation of A12 0 3 crystals. The net integrated intensity was calculated in order to compare the intensity among the different thickness samples whose thickness is thinner than X-ray penetration depth. The electrical resistivity depends on the relative X-ray intensity of (110) and (300) of a-A120 3. INTRODUCTION It is well-known that aluminum oxide (A120 3) has an excellent electrical insulating property at high temperature. However, A120 3 films, prepared by a conventional deposition process, are not suitable to form electrical insulating layers for electric devices such as thin film sensors[1] at a high temperature. Because the resistivity of insulating films decreases considerably with temperature. We are carrying out research to produce dense insulating films with closely packed grains by ion beam assisted plasma CVD in order to improve the insulating property at high temperature. Previously, the authors have reported on the A120 3 films prepared by this process[2-3]. It was found that the A120 3 films prepared by this process showed superior adhesion strength compared with that by a conventional plasma CVD and simultaneous irradiation of the ion beams during plasma CVD enhanced crystallization and/or growth of fine grain structure which was not obtained by plasma and thermal CVD at lower temperature[3]. a-A120 3 crystals were obtained by ion beam assisted plasma CVD at the substrate temperature of 8001C with irradiation of 10 keV krypton ions. The film was remarkably crystallized and consisted of fine grain compared with the films by the conventional plasma CVD[3]. This film showed higher electrical resistivity at high temperature than the films prepared by conventional CVD at the same substrate temperature, and it was suggested that the film prepared by ion beam assisted plasma CVD has preferential orientation[3]. The incident angle of the ion beams to the substrate influenced the
orientation of A12 0 3 crystals. In this paper, the effect of the incident angle of the ion beams during ion beam assisted plasma CVD on the orientation of A12 0 3 crystals is mainly described, and the relationship between crystallinity and electrical resistivity is discussed. The crystallinity of these films was analyzed by X-ray diffraction (XRD) using CuKa. The net integrated intensity was calculated in order to compare the intensity among the different thickness samples whose thickness is thinner than Xray penetration depth. 319 Mat. Res. Soc. Symp. Proc. Vol. 504 ©1998 Materials Research Society
EXPERIMENT A120 3 films were deposited on the nickel based superalloy (Inconel 718) by ion beam assisted plasma
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