Recent Progress in Industrial Applications of CAT-CVD (Hot-Wire Cvd)
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RECENT PROGRESS IN INDUSTRIAL APPLICATIONS OF CAT-CVD (HOT-WIRE CVD) Atsushi Masuda, Akira Izumi, Hironobu Umemoto and Hideki Matsumura School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST), Asahidai, Tatsunokuchi, Ishikawa 923-1292, Japan ABSTRACT Rapid progresses are achieved in catalytic CVD (Cat-CVD), often called hot-wire CVD, in the past 3-years NEDO national project in Japan. Cat-CVD technology presents many advantages in thin-film formation processes; high-efficiency of gas use, large-area deposition, no ion bombardment and low-temperature deposition even below 200 OC. All of the elemental techniques for the industrially applicable Cat-CVD apparatuses, such as the suppression of the metal contamination, the precise control of the substrate temperature, the life extension of the catalyzer, 1-m size uniform deposition and the chamber cleaning, have been completely developed. Sophisticatedly designed substrate holder with electrostatic chuck and showerhead equipped with catalyzers are both key technologies for these achievements. High reproducibility for film properties is also obtained by controlling the reaction between high-density radicals and chamber walls. Prototype mass-production apparatus for SiNx passivation films in GaAs devices has been already developed and this will be probably the first application of Cat-CVD in industry. These recent movements appear to promise the drastic revolution in semiconductor and flat-panel display industries by introducing Cat-CVD in very near future. INTRODUCTION Catalytic chemical vapor deposition (Cat-CVD), often called hot-wire chemical vapor deposition (HWCVD) mainly in USA or Europe, has recently attracted much attention since industrial application of Cat-CVD begins just now. The first report on Cat-CVD was published in 1985 by Matsumura et al. [1,2], one of the co-authors in this article, although some preliminary results had been presented by Yamazaki et al. in 1970 [3] and Wiesmann et al. in 1979 [4]. In the first report hydro-fluorinated amorphous Si (a-Si:F:H) films are prepared by Cat-CVD method using SiF2 intermediate species, produced by pyrolysis of SiF4, and H2. H2 gas molecules are decomposed on W catalyzer and a-Si:F:H films are deposited on substrates through the reaction between H atoms and SiF2 intermediate species. In this case heated W catalyzers are used only for the decomposition of H2 gas molecules. Later, both SiH4 and H2 gas molecules are decomposed on heated W catalyzers and hydrogenated amorphous Si (a-Si:H) films are formed [5]. Recently, it is clarified that dominant decomposition reaction of SiH4 does not occur on the catalyzer but occurs in the gas phase near the catalyzer by the collision with H atoms [6]. Based on the finding primitive style Cat-CVD [1,2] in which only H2 molecules are decomposed on the catalyzer into H atoms and Si-based gases are decomposed by transported H atoms in the other chamber may revive in near future [7]. In Cat-CVD method gas molecules are decomposed by the 2-dimensional
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