Patent ID: 7524397
Filing Date: 2009-04-28
Classification: H01J

Abstract:
1. A pedestal for supporting a substrate during plasma processing, said pedestal comprising: an electrode configured for generating an electric field; a chuck disposed above said electrode, said chuck being configured for holding said substrate; a generally planar edge ring disposed above said electrode and extending underneath a substrate when positioned on said chuck, said edge ring being formed from a dielectric material and configured for shielding said electrode and said chuck with inner edge portions proximate an edge of said substrate and an edge of said chuck and an outer edge portion extending to one edge of said electrode; and an impedance matching layer disposed and confined between said electrode and said edge ring and underneath said substrate when said substrate is resting on said pedestal, said impedance matching layer being entirely planar and parallel with a top surface of the electrode and a bottom surface of the edge ring, said impedance matching layer being bonded to said electrode or said edge ring, said impedance matching layer having characteristics or features configured for controlling an impedance between said electrode and a plasma, said impedance being arranged to affect said electric field, wherein a first impedance produced through said chuck is different than a second impedance produced through said edge ring, and wherein said impedance matching layer is configured to alter said second impedance produced through said edge ring so that said second impedance is substantially equal to said first impedance produced through said chuck, the equalization of said impedances improving processing uniformity across the surface of said substrate by coupling energy more uniformly across the surface of the substrate.