PURPOSE: To provide a semiconductor manufacturing equipment, such as the low-pressure CVD device, etc., in which the concentration of a process gas made to flow through a furnace tube in which semiconductor wafers are arranged is made uniform on the surfaces of the wafers.

CONSTITUTION: In a semiconductor manufacturing equipment in which a furnace tube 4 composed of an inner and outer tubes 2 and 3 is arranged on a base 1, semiconductor wafers 7 held in a boat 8 are put in the inner tube 2, and a process gas is supplied toward the wafers 7 from a port 6 opened through the base 1 by rotating the boat 8 and wafers 7, a gas diffusing plate 20 is arranged perpendicularly to the flow passage of the process gas so that the plate 20 can be rotated together with the boat 8. In addition, the process gas is made to uniformly flow on the surfaces of the wafers 7 by protruding gas stirring vanes 23 from the internal surface of the plate 20 and rotating the vanes 23 by rotating the plate 20 so that the process gas can be stirred and can be made to pass through the plate 20 in a uniform state.