| 摘要 |
PURPOSE:To return the pressure in a vacuum vessel to fixed pressure rapidly even when the pressure alters by a method wherein the number of revolution of vacuum pumps is changed in response to the variation of the discharging impedance of a spatter electrode or an etching electrode of the vacuum vessel. CONSTITUTION:A vacuum vessel 11 is provided with an introducing pip 12 to which a variable leaking valve for introducing etching gas is attached, and vacuum pumps 13, 14 for exhausting the gas are fitted. A base body 20 on which a pattern is placed and an anode 21 are attached into the vacuum vessel 11, the base body 20 is connected to a DC power source 22 or an AC power source 23, and the anode 21 is grounded. Meanwhile, a detector 24 is fitted between the base body 20 and the ground, and a varying portion of discharging impedance between the anode 21 and the base body 20 is detected by means of the detector 24. The detecting output is given to a comparator 25 in which the reference voltage is previously set, and the difference is amplified 27 and forwarded to a motor 28 of the pump 13 to control the number of revolution of the motor. Thus, pressure in the vessel 11 is kept constant within the desired range, and uniform etching is enabled at all times. |
