PURPOSE: To recover gaseous hydrogen without fluctuating the pressure in a CVD furnace with a device for recovering waste gaseous hydrogen by providing a stop valve between a suction pump and a refining and providing a bypass stop valve to the suction pump.
CONSTITUTION: The pressure in pipings 4, 6 drops when a feed valve and a discharge valve are closed upon ending of a vapor growth process in a CVD furnace 11. When a sensor attached to a pressure regulator 5 senses a pressure drop, a pressure indicating controller 14 throttles the opening degree of a stop valve 9 and opens a bypass stop valve 13 allowing the greater part of the waste gas to circulate through an impurity remover 7, a suction pump 8 and the valve 13. The pressure drop between the position where the piping 6 and a bypass piping 12 are connected and the CVD furnaces 11, 11, 13 is thus made slight. Even if the feed valve and discharge valve for operating the succeeding furnace 12 are opened, the abrupt fluctuation of the pressure in the furnace 12 is prevented and the gaseous hydrogen is recovered without decreasing the yield of a semiconductor product.
SUZUKI TATSUJI
TAKAHASHI SHIYOUICHI
YANO MAKOTO
TOKUYAMA SERAMITSUKUSU KK
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