POWER SOURCE MATCHING CIRCUIT IN PLASMA ETCHING DEVICE

PURPOSE:To stabilize electric discharge in a chamber by adjusting the electrostatic capacitances of first and second variable capacitors provided in front and rear of a coil since the electric discharge condition in the chamber caused by a plasma outlet varies, depending upon the size of the chamber, the pressure and kind of treating gas, a source power, the kind of a specimen and the like. CONSTITUTION:In order to stabilize the electric discharge condition in a chamber 7, a type matching circuit 15 as a power source is provided between a table 5 and an amplifier 13 connected to a high frequency oscillator 11. A front variable capacitor 19 and a rear variable capacitor 21 are connected in parallel in front and rear of a coil 17 constituting the circuit 15. In this arrangement, the capacitors 19, 21 are composed finely adjusting first variable capacitors 19A, 21A and roughly adjusting second capacitors 19B, 21B, respectively. A detector 23 is provided between the amplifier 13 and the capacitor 10, for detecting a difference between a plasma input wave and a reflecting wave returned after electric discharge, and accordingly, the electrostatic capacitances of the capacitors are adjusted so that the difference approaches the input wave.