Method for distributing gas for a bevel etcher
A plasma etch processing chamber configured to clean a bevel edge of a substrate is provided. The chamber includes a bottom edge electrode and a top edge electrode defined over the bottom edge electrode. The top edge electrode and the bottom edge electrode are configured to generate a cleaning plasma to clean the bevel edge of the substrate. The chamber includes a gas feed defined through a top surface of the processing chamber. The gas feed introduces a processing gas for striking the cleaning plasma at a location in the processing chamber that is between an axis of the substrate and the top edge electrode. A pump out port is defined through the top surface of the chamber and the pump out port located along a center axis of the substrate. A method for cleaning a bevel edge of a substrate is also provided.
1. A method for cleaning a bevel edge of a wafer in a chamber having a wafer support, the chamber used for plasma etching of the bevel edge, comprising:
positioning the wafer on the wafer support, wherein a periphery of the wafer extends beyond an edge of the wafer support, the chamber having a distribution plate parallel to the wafer and spaced apart from a top surface of the wafer not more than 0.6 mm, and a region where the wafer extends beyond the edge of the wafer support is where the bevel edge of the wafer resides during plasma etching;
flowing a process gas to a periphery of the chamber proximate to the bevel edge of the wafer;
pumping an inert gas into a center region of the chamber, the pumping being controlled to define a pressure gradient across the wafer to correct deformations in the wafer;
generating a plasma with the process gas proximate to the bevel edge of the wafer to start processing of the bevel edge;
throttling a process pump down rate of the chamber proximate to the bevel edge during the processing via a bypass line, such that a pressure of the chamber is controlled during the processing; and
pumping down the chamber upon completing the processing, the pumping down being enhanced via a pumping line that is parallel to the bypass line, the pumping line having a greater diameter than the bypass line.
2. The method of claim 1 , wherein the pressure gradient acts to manipulate the wafer so as to flatten a curved or bowed wafer, the flattening acting to assist in improving process uniformities across the wafer.
3. The method of claim 1 , wherein the method operation of flowing a process gas proximate to the bevel edge of the wafer to start processing of the bevel edge further includes,
delivering the process gas through a single point of entry into the chamber.
4. The method of claim 1 , wherein throttling the process pump down rate and the pumping down is controlled by a controller, while the controller further controls the flowing of the process gas to the periphery of the chamber proximate to the bevel edge, such that the pressure in the chamber is monitored and controlled during the processing.
5. The method of claim 1 , further comprising:
terminating plasma generation;
closing valves used for the throttling of the process pump down rate;
activating valves used for pumping down the chamber.
6. The method of claim 5 , wherein valves used for the throttling are positioned in parallel to valves used for the pumping down of the chamber.