Impedance control of local areas of a substrate during plasma deposition thereon in a large pecvd chamber

Abstract

Embodiments of the present disclosure generally relate to methods and apparatus for measuring and controlling local impedances at a substrate support in a plasma processing chamber during processing of a substrate. A substrate support includes a plurality of substrate support pins wherein the radio frequency voltage, current and phase of each of the plurality of substrate support pins are measured and impedances of the support pins are adjusted in real time. Each of the substrate support pins is coupled to an associated adjustable impedance circuit that may be remotely controlled. In one embodiment a variable capacitor is used to adjust the impedance of the impedance circuit coupled to the associated substrate support pin and may be remotely adjusted with a stepper motor. In another embodiment a microcontroller may control the impedance adjustments for all of the plurality of substrate support pins and may be used to track these impedances with each other and with a bulk impedance of the plasma processing chamber.