Abstract: Methods and apparatus for processing a substrate are provided herein. For example, apparatus can include a first voltage/current (V/I) probe configured to connect to an input side of a matching network of the processing chamber and a second V/I probe configured to connect to an output side of the matching network and a processor coupled to the first V/I probe and the second V/I probe and configured to, based on a phase gap between a V and I of an RF signal detected by at least one of the first V/I probe or the second V/I probe at a target frequency, detect a minimum phase gap between the V and I, and control at least one of impedance tuning of the matching network or process control of the processing chamber using at least one of a peak or RMS of V, I and phase measured at the target frequency or under sweeping frequency.

Abstract: Methods and apparatus for matching an impedance of a process chamber with an impedance of an RF power source. In some embodiments, a method comprises dynamically matching a load impedance of the process chamber with an impedance matching circuit coupled between an RF power source and the process chamber, the impedance matching circuit configured to compensate for changes in the load impedance to match an impedance of the RF power source over a wide range of load impedances; filtering power feeding back from the process chamber with a first filter positioned between the matching circuit and the process chamber, the first filter configured as a wide bandpass filter; and filtering residual signals with a second filter positioned between the matching circuit and the RF power source, the second filter configured as a low pass filter.