To control a temperature inside a furnace for uniform distribution in a diffusion furnace type semiconductor manufacturing equipment, where a semiconductor wafer is carried into the diffusion furnace for high temperature heat treatment of the semiconductor wafer, and then an impurity gas is introduced into the furnace to form an impurity diffusion film on the wafer, with the impurity being diffused uniformly.

The diffusion furnace type semiconductor manufacturing equipment 1 comprises a core tube for carrying a semiconductor wafer into an inner space, with the furnace for heating surrounding and inner-packaging the core tube, a gas exhaust pipe for exhausting the gas introduced into the core tube, and a hot-air exhaust pipe for exhausting a heated gas which is connected to the furnace. In the diffusion furnace type semiconductor manufacturing equipment 1, both the gas exhaust pipe 12 and the hot-air exhaust pipe 13 are provided with variable valves 14 and 15 for controlling the exhaust pressure, and a controller 16 for exhaustion is also provided which controls the variable valves, so as to keep constant the exhaustion balance, between the gas exhaust pipe and the hot-air exhaust pipe.