| 摘要 |
PURPOSE:To match at high speed and high accuracy by obtaining an impedance viewing from an output terminal toward a plasma generator while detecting a voltage at the output terminal of an RF generator and a current flowing to the plasma generator, and forming a closed control system comparing the impedance with a reference value to regulate the result automatically. CONSTITUTION:A servo motor M1 in a closed control loop acts like adjusting a capacitor C1 to make a comparison output e3 of a differential amplifier DA appearing when an input impedance ZP viewed from a point b-b' is higher and lower than 50OMEGA into a value zero at all times, thereby bringing the input impedance ZP into 50OMEGA. Then a capacitor C2 is controlled immediately to make a comparison difference output e4 based on the phase difference between V0 and I0 caused by the adjustment of the capacitor C1 zero thereby bringing the output voltage V0 of the RF generator A and the load current I0 in phase. Thus, the impedance matching is quickened at high speed and proper impedance matching is applied at all times in response to the load state of a plasma generator changing timewise for example, then the matching accuracy is improved.
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