Method and apparatus for monitoring and adjusting chamber impedance

Abstract

A substrate processing system that includes a deposition chamber having a reaction zone, a substrate holder that positions a substrate in the reaction zone, a gas distribution system that includes a gas inlet manifold for supplying one or more process gases to said reaction zone, a plasma power source for forming a plasma from a process gas introduced into the reaction zone of the deposition chamber and an impedance monitor that is electrically coupled to the deposition chamber to measure an impedance level of the plasma. In a preferred embodiment, the substrate holder is a first electrode and the gas inlet manifold is a second electrode and RF power is supplied by the plasma power source to either the first or second electrodes to form the plasma. In another preferred embodiment, the processing system further includes a computer processor that is communicatively coupled to the impedance monitor and to other control systems of the processing system so that the computer processor can adjust the impedance of the deposition chamber during the course of an extended wafer run if the impedance drifts outside of a predetermined tolerance range.