Rapid Epitaxial Growth of Si and SiGe Mono-Crystalline Films on Silicon-on-Glass Substrates by Reactive CVD Using SiH 4
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Rapid Epitaxial Growth of Si and SiGe Mono-Crystalline Films on Silicon-on-Glass Substrates by Reactive CVD Using SiH4, GeH4, and F2 Hiroshi Noge1,3, Akira Okada1, Ta-Ko Chuang2, J. Greg Couillard2, and Michio Kondo3,4 1
Corning Holding Japan GK (CJGK), Akasaka Intercity 6F, 1-11-44 Akasaka, Minato-ku, Tokyo 107-0052, Japan 2
Corning® Incorporated, Corning, NY 14831, USA
3
National Institute of Advanced Industrial Science and Technology (AIST), Research Center for Photovoltaic Technologies, Central 2, 1-1-1 Umezono, Tsukuba-shi, Ibaraki-ken 305-8568, Japan 4
Tokyo Institute of Technology, Department of Innovative and Engineered Materials, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa-ken 226-8502, Japan ABSTRACT We have succeeded in the rapid epitaxial growth of Si, Ge, and SiGe films on Si substrates below 670 ºC by reactive CVD utilizing the spontaneous exothermic reaction between SiH4, GeH4, and F2. Mono-crystalline SiGe epitaxial films with Ge composition ranging from 0.1 to 1.0 have been successfully grown by reactive CVD for the first time. This technique has also been successfully applied to the growth of these films on siliconon-glass substrates by a 20 - 50 ºC increase of the heating temperature. Over 10 Pm thick epitaxial films at 3 nm/s growth rate are obtained. The etch pit density of the 5.2 Pm-thick Si0.5Ge0.5 film is as low as 5 x 106 cm-2 on top. Mobilities of the undoped SiGe and Si films are 180 to 550 cm2/Vs, confirming the good crystallinity of the epitaxial films. INTRODUCTION Crystalline silicon is a widespread material for LSI and photovoltaic applications. Its compound with germanium is expanding the usage for faster processors and longer wavelength devices. When mono-crystalline Si and SiGe thin films can be formed on low-cost, large, transparent, and insulating substrates such as glass instead of conventional bulk crystal wafers, it could be attractive for semiconductor, display, and photovoltaic industries. Corning® has developed Silicon-on-Glass (SiOG) technology, where a 200 - 300 nm thick mono-crystalline Si film is bonded onto a glass substrate [1]. Although this technology enables a large reduction in Si material consumption compared to a mono-crystalline bulk substrate, semiconductor processes such as epitaxial growth should be performed below the glass strain point; around 660 ºC for Corning EAG®LE XG® glass. One of the authors previously reported homo-epitaxial growth of Si at 400 ºC at a maximum rate of 1.7 nm/s by reactive CVD (R-CVD) based on the gas phase reactions between SiH4 and F2 [2]. However, the maximum thickness without breakdown of epitaxy was limited to 3 Pm. In this work, a wide range of growth conditions has been investigated. As a result, much higher growth rate and thicker mono-crystalline Si films have been obtained on both Si and SiOG substrates. Furthermore, mono-crystalline SiGe epitaxial films with Ge composition
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ranging from 0.1 to 1.0 have been successfully grown on Si and SiOG substrates by R-CVD using SiH4, GeH4, and F2 for the first
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