An ultra clean CVD (Chemical Vapor Deposition) epitaxial growth system was developed to grow high quality epitaxial silicon films. Introduction of newly-developed ultra high vacuum compatible reactor having carbon susceptor with minimized contamination as well as an electrostatic wafer chucking/transfer mechanism working in high vacuum realized an ultra clean environment for epitaxy. As a result, defect-free epitaxial silicon films were obtained at low temperatures of less than 900 degree C, when substrates were heat-treated under the ultra high vacuum before epitaxial growth. The generation lifetime and the carrier concentration of epitaxial films grown in this system were typically 4. 7 msec and 8 multiplied by 10**1**2cm** minus **3, respectively.