US Patent 11698191 Ignition method of plasma chamber

An ignition method of a plasma chamber includes steps of: (a) starting softly an ignition voltage to a first voltage, (b) decreasing the magnitude of the ignition voltage to a second voltage after a first ignition time, (c) increasing the magnitude of the ignition voltage to the first voltage after a second ignition time, and (d) repeating the step (b) and the step (c) until the ignition is successful.