Patent ID: 9593411
Date: 2017-03-14
CPC Classifications: C23C,H01J

Claim:
1. Apparatus for performing physical vapor deposition on a wafer disposed in a physical vapor deposition (PVD) chamber, comprising: a target comprised of metallic material disposed in the PVD chamber, wherein the target provides a first electrode to the PVD chamber; a wafer support for supporting the wafer disposed in the PVD chamber, wherein the wafer support provides a second electrode to the PVD chamber; a VHF generator to apply an RF plasma source power to the target to generate a plasma at the target; an impedance match network coupled between the VHF generator and the target; a first variable impedance element coupled between the wafer support and ground, and independent from the impedance match network, to control a plasma sheath voltage during a physical vapor deposition process by tuning an impedance at the wafer support, wherein the first variable impedance element includes a variable capacitor configured to tune an impedance of the wafer support at a frequency of the VHF generator that allows current at the frequency to flow along a first VHF ground return path from the wafer support to ground; a second VHF ground return path from a sidewall of the chamber to ground; and a second variable impedance element disposed in the second VHF ground return path and coupled between the sidewall of the chamber and ground, wherein the first and second variable impedance elements are configured to limit a bias voltage on the wafer by apportioning resistances at the frequency of said first and second VHF ground return paths, wherein the impedance match network, the first variable impedance element, and the second variable impedance element are separate circuits that are not connected to each other.