Patent ID: 9275838
Filing Date: 2016-03-01
CPC Classification: H01J

Claim Text:
1. An arrangement for controlling bevel etch rate during plasma processing within a processing chamber of a plasma processing system, comprising: a power source; a gas distribution system; a lower electrode, wherein said lower electrode is configured at least for supporting a substrate during said plasma processing; a top ring electrode positioned to cover a top edge of said substrate; a bottom ring electrode positioned to cover a bottom edge of said substrate; a first match arrangement disposed between said top ring electrode and ground, said first match arrangement is configured at least to control current flowing through said top ring electrode to control amount of plasma available for etching at least a part of a top edge of said substrate, wherein the first match arrangement includes a first parallel circuit comprising a series circuit of a variable capacitor and a first inductor connected in parallel to a series circuit of a second inductor and a switch; a second match arrangement disposed between said bottom ring electrode and ground and is configured to control said current flowing through said bottom ring electrode to control amount of plasma available for etching at least a part of a bottom edge of said substrate, wherein the second match arrangement includes a second parallel circuit comprising a series circuit of a variable capacitor and a first inductor connected in parallel to a series circuit of a second inductor and a switch; and an upper electrode positioned directly above said substrate, the upper electrode having a surface that substantially covers a top surface of the substrate except for the top edge of the substrate, the upper electrode having an extension that extends the surface of the upper electrode up to the top edge of the substrate, the upper electrode and the extension of the upper electrode being disposed over the top surface of the substrate such that a gap that is less than about .35 mm is maintained to prevent formation of plasma in an area between the upper electrode and the top surface of the substrate; a first ceramic element is disposed between the extension and the top ring electrode; a second ceramic element is disposed between the lower electrode and the bottom ring electrode; and a third match arrangement, wherein said third match arrangement is coupled to said upper electrode, wherein said third match arrangement is configured to control said current flowing through said upper electrode to change said upper electrode from a grounded state to a floating state, thereby minimizing plasma formation between said upper electrode and said lower electrode; wherein said third match arrangement includes at least a switch, an inductor, and a variable capacitor, the inductor is in series with the variable capacitor of the third match arrangement, wherein said switch of the third match arrangement is set to a closed position, wherein said inductor and said capacitor of the third match arrangement is tuned to be in parallel resonance with an operating frequency of said processing chamber to set said upper electrode at said floating state.