Patent ID: 7575638

Claim:
An etching chamber, comprising: a lower electrode being primarily conductive and defined for supporting a wafer directly on the top surface of the lower conductive electrode, wherein the lower electrode has a lower edge section; a top electrode configured to have a center area that is not powered, the center area being configured to be positioned in close proximity to a central area of the wafer when the wafer is supported by the lower electrode, wherein the top electrode has a top edge section, and wherein the close proximity of the center area of the top electrode and the central area of the wafer defines an inactive etching zone to inhibit etching of the central area of the wafer; an annular region defined between the top electrode and the lower electrode, wherein the annular region defines an active etching zone being configurable to enable etching of a unique edge environ of the wafer; a top etch defining ring configured to define a portion of the active etching zone corresponding to a portion of the unique edge environ extending along a top length of an upper surface of the wafer from a wafer edge, the top length being in the active etching zone, wherein the top etch defining ring separates the top edge section of the top electrode from a center portion of the top electrode, and wherein the top etch defining ring being configured to be removable and replaceable to change the top length, and wherein the top etch defining ring is a single piece; and a bottom etch defining ring configured to define another portion of the active etching zone corresponding to another portion of the unique edge environ extending along a bottom length along a bottom surface of the wafer from the wafer edge, the bottom length being in the active etching zone, wherein the bottom etch defining ring separates the lower edge section of the lower electrode from a center portion of the lower electrode, and wherein the bottom etch defining ring being configured to be removable and replaceable to change the bottom length, and wherein the bottom etch defining ring is a single piece.