対向ターゲット型スパッタシステムを用いたGeSbTe薄膜に関する研究(第3報) : 膜の微細構造と光学的特性に関する考察

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A lens-less optical floppy disk system has been proposed. Our group have also been researching film-formation techniques as a key issue in fabrication these disks. This paper reports on a facing-targets sputtering (FTS) system as a newest technique for forming Ge_2Sb_2Te_5 thin film on a phase-change recording medium. When the films were prepared by FTS application, it was shown that the homogeneous and uniform in film thickness. The crystal structure of the films was analyzed by an X-ray diffractometer. Diffractions were clearly obtained from a sample which was prepared with the substrate temperature at 140℃ during film formation. This indicates that the film is polycrystalline. These diffractions can be used to calculate a lattice constant, mirror index, etc. Reflectivity was measured using a spectrophotometer in the wavelength range from 200 to 900 nm. A high value of about 70% was obtained for the sample, the crystalline film, while all of the other amorphous films exhibited reflectivity below 50%. On the other hand, the sample which showed the lowest reflectivity was formed under high sputter gas pressure of 1.2 Pa. The surface conditions were observed using an atomic force microscopy and an SEM. There were clear differences in film flatness. It was found that surface conditions and surface morphology have a great effect on reflectivity.
東海大学の論文
2000-03-10