PURPOSE: To suppress the fluctuation in the temperature distribution of furnace due to the accumulated film pressure of silicon without requiring preheat by making a furnace tube and the like of a silicon based material.

CONSTITUTION: In a silicon filming system, an outer furnace tube 1, an inner furnace tube 2, a thermal insulation tube 3, and a board 4 are made of silicon. Consequently, even if silicon adheres to the surface of the furnace tubes 1, 2, the thermal insulation tube 3, and the board 4 through use and the accumulated thickness of silicon increases, the specific heat thereof does not change. Since the fluctuation of temperature distribution in the furnace due to the fluctuation of accumulated thickness of silicon is substantially eliminated, the uniformity of temperature distribution is improved without requiring preheat. Since preheat is not required, operating rate of silicon filming system can be enhanced substantially.