US Patent 9378931 Pulse plasma apparatus and drive method thereof

A pulse plasma apparatus includes a process chamber, source RF generator configured to supply first and second level RF pulse power having first and second duty cycles to an upper electrode of the process chamber, a reflected power indicator configured to indicate reflection RF power, a first matching network, and a controller. The first matching network is configured to match an impedance of the process chamber with an impedance of the source RF generator as a first or second matching capacitance value, respectively when the first level RF pulse power or second level RF pulse power is supplied, respectively. The controller is configured to calculate a third matching capacitance value based on the first and second matching capacitance values and a ratio of the first and second duty cycles, provide the third matching capacitance values to the first matching network, and control the source RF generator and first matching network.