| 摘要 |
PURPOSE:To simplify the work of controlling the gas flow rate in a gas flow rate controller by a method wherein the gas flow rate controller is provided with an electric circuit in such a constitution that the total gas flow rate of the oxygen gas flow rate and the nitrogen gas flow rate is always held at a constant value using the electrically controllable mass flow controllers. CONSTITUTION:Nitrogen gas (a) and oxygen gas (b) are flowed through the gas bungholes at a proper ratio. Power is applied to a diffusion furnace 1 and the diffusion furnace 1 is made to rise to a high temperature. Wafers 3, whereon emulsion solution containing diffusion- purposed element is applied in advance, are erected on a quartz boat 4, the quartz boat 4 is put in a quartz tube 2 and a heat treatment is performed. When the oxygen gas flow rate is A liter/ component and the nitrogen gas flow rate is B liter/component, the total gas flow rate of the oxygen gas flow rate and the nitrogen gas flow rate is set in advance in an electrical operational part 9 is such a way as to become A+B=K (the K is a constant value). At this time, when a polentiometer 8 for oxygen gas flow rate control is adjusted for adjusting the resistivities of the gas layers, a mass flow controller 5 acts by electric signal and the oxygen gas flow rate changes, but at the same time, a mass flow controller 6 for nitrogen gas flow rate control acts by signal from the operational part 9, the nitrogen gas flow rate fluctuates and the total gas flow rate of both gas flow rates do not change.
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