Impedance matching

A method of matching impedance with an impedance matching circuit, the method comprising:

• transforming, by a first reactance arrangement, an impedance of a load to an impedance within a range of a nominal impedance of an HF generator in a normal matching mode;
• while the impedance matching circuit is operating in the normal matching mode, causing the impedance matching circuit to operate in the protection mode in response to determining that the load is in a hazardous state;
• and
• altering a switching state of a PIN diode switch from a first invariable switching state in the normal matching mode to a second switching state in the protection mode to form a second reactance arrangement configured to transform an impedance of the load to prevent damage to the HF generator or to transmission circuitry arranged between the HF generator and the further comprising applying a reverse bias voltage with initial overshoot to the PIN diode switch to reverse bias the PIN diode switch.

A plasma load impedance matching circuit selectively operable in a normal matching mode and a protection mode, the circuit comprising:

• a control circuit configured to, while the plasma load impedance matching circuit is operating in the normal matching mode, cause the plasma load impedance matching circuit to operate in the protection mode in response to determining that a load is in a hazardous state;
• a set of reactances in a first reactance arrangement configured to transform an impedance of the load to an impedance within a range of a nominal impedance of an HF generator in the normal matching mode;
• and
• a PIN diode switch having a first invariable switching state in the normal matching mode, and a second switching state that reconfigures the set of reactances into a second reactance arrangement in the protection mode;
• wherein the second reactance arrangement is configured to transform the impedance of the load to an impedance sufficient to prevent damage to the HF generator or to transmission circuitry arranged between the HF generator and the load and further comprising a DC voltage source having an associated overshoot device and associated with the PIN diode switch to produce a reverse bias voltage.