A
semiconductor device manufacturing apparatus is provided. The
semiconductor device manufacturing apparatus comprises a furnace having a closed predetermined space for seating a
wafer, a loading device located at one side of the furnace to load the
wafer on which a prior process may have been performed, a
gate valve interposed between the furnace and the loading device to selectively open / close a pathway between the furnace and the loading device, a heater for heating an interior of the furnace, a
vacuum pump for maintaining the interior of the furnace with a suitable pressure necessary to the process, a gas reservoir for storing individually various kinds of reaction gases supplied from an exterior of the space, a
gas mixing device connected to the gas reservoir to mix the various kinds of reaction gases supplied from the gas reservoir with an even
mixing ratio, at least two mixed gases supply pipes connected to the
gas mixing device to supply the reaction gases mixed in the
gas mixing device to each direction of the furnace, and a mixed gases flow
control unit installed at the mixed gases supply
pipe to control the flow of the reaction gases supplied through the mixed gases supply
pipe.