| 摘要 |
PURPOSE:To enhance constancy of the pressure difference, while to curtail time necessary for raise of pressure or reduction of pressure at a high pressure oxidation device by a method wherein a pressure control system to be used when pressure rose and a pressure control system to be used when pressure dropped are formed in the separate systems. CONSTITUTION:A reactiok tube 3 is accommodated in a high pressure vessel 1, and oxide films are formed on semiconductors accommodated in the tube 3 holding the difference between inside pressures of the vessel 1 and the tube 3 at a constant. A pressure difference detecting means 6 generates the first signal being different from a signal indicating the previously decided pressure difference when inside pressure of the tube 3 rose. The means 6 generates also the second signal being different from the signal indicating the previously decided pressure difference when reaction in fixed pressure is to be performed and when pressure dropped. The first servo valve SV-1 is controlled responding to the first signal, and the second servo valve SV-2is controlled responding to the second signal to hold the pressure difference thereof at a constant. Accordingly, constancy of the pressure difference can be enhanced, time necessary for raise of pressure or reduction of pressure can be curtailed, and as a result, the rate of operation of the device also can be enhanced. |
