Abstract: In a chemical vapor deposition system, susceptors are supported by a pair of turntables which are disposed in a vertical and parallel arrangement. A plurality of wafers to be processed are arranged circumferentially on opposing surfaces of the susceptors, and heater units are arranged behind the turntables. Because the wall surfaces exposed to the material gas are mostly covered by the wafers to be processed, any wasteful deposition of material on the chamber surfaces can be avoided. Thus, the need to clean the surface of the chamber wall is minimized. Such material deposition is not only wasteful but also could become a source of contamination as such deposition tends to peel off.