Impedance Matching Device and Impedance Matching Method

An impedance matching device to achieve impedance matching between a high-frequency power source and a load, the impedance matching device comprising:

• a variable capacitor including a plurality of capacitance elements respectively having capacitor each having one end connected to the high-frequency power source and semiconductor switch connected in series to the capacitor, the plurality of capacitance elements being connected in parallel;
• and
• a control unit coupled to an impedance information detection unit located between the power source and the impedance matching device to generate tuning signals to controls an on or off state of the each of semiconductor switches so as to match an output impedance of the high-frequency power source and an impedance of the load based on information concerning the impedance obtained,
• wherein the control unit generates the tuning signals by calculating a reflection coefficient, a reflected power, a reflected voltage or a reflected current based on the information obtained by the impedance information detection unit concerning the impedance viewed from the high-frequency power source toward a load side of the load, updates the on or off states of the semiconductor switches included in the plurality of capacitance elements with a first update cycle in a case where the reflection coefficient, the reflected power, the reflected voltage or the reflected current is equal to or more than a predetermined value, and updates the on or off states of the semiconductor switches included in the plurality of capacitance elements with a second update cycle longer than the first cycle where the reflection coefficient, the reflected power, the reflected voltage or the reflected current is less than the predetermined value.

An impedance matching method achieving impedance matching between a high-frequency power source and a load by a variable capacitor provided between the high-frequency power source and the load, the variable capacitor including a plurality of capacitance elements respectively having a capacitor and a semiconductor switch, the method comprising:

• calculating a reflection coefficient, a reflected power, a reflected voltage or a reflected current based on information obtained by an impedance information detection unit concerning an impedance viewed from the high-frequency power source toward a load side of the load;
• updating on or off states of the semiconductor switches included in the plurality of capacitance elements with a first update cycle where the reflection coefficient, the reflected power, the reflected voltage or the reflected current is equal to or more than a predetermined value;
• and
• updating the on or off states of the semiconductor switches included in the plurality of capacitance elements with a second update cycle longer than the first cycle where the reflection coefficient, the reflected power, the reflected voltage or the reflected current coefficient is less than the predetermined value.