Apparatus and method for controlling edge performance in an inductively coupled plasma chamber

An apparatus for processing a substrate, comprising:

• a chamber body encompassing a process volume;
• a gas inlet configured to flow a process gas into the process volume;
• and
• a supporting pedestal disposed in the process volume, wherein the supporting pedestal comprises:
• a top plate having a substrate supporting surface, wherein the substrate supporting surface is a continuous ring, a recess on an upper surface of the top plate and circumscribed by the substrate supporting surface, and an edge surface circumscribing and extending radially outside of the substrate supporting surface;
• a plurality of supporting islands protruding from the top plate radially outward the substrate supporting surface, wherein the plurality of supporting islands extend vertically higher than the substrate supporting surface and an inner surface of each of the plurality of supporting islands is separated from an outer edge of the substrate supporting surface by a groove;
• and
• an edge ring disposed on the edge surface of the top plate and radially outward the plurality of supporting islands, wherein an upper surface of the substrate and an upper surface of the edge ring are disposed with a height difference between each other.