Remote Capacitively Coupled Plasma Source with Improved Ion Blocker
Apparatus and methods for generating a flow of radicals are provided. An ion blocker is positioned a distance from a faceplate of a remote plasma source. The ion blocker has openings to allow the plasma to flow through. The ion blocker is polarized relative to a showerhead positioned on an opposite side of the ion blocker so that there are substantially no plasma gas ions passing through the showerhead.
1 . A gas distribution apparatus comprising:
an ion blocker spaced a distance from a faceplate of a remote plasma source, the ion blocker having a distance defined by a front surface and a back surface and the thickness comprises a plurality of openings extending therethrough;
a showerhead spaced a distance from the ion blocker, the showerhead comprising a plurality of apertures to allow radicals from the remote plasma source to flow through the showerhead; and
a voltage regulator connected to the ion blocker and the showerhead, the voltage regulator configured to polarize the showerhead relative to the ion blocker to generate a flow of radicals through the showerhead that is substantially free of ions.
2 . The gas distribution apparatus of claim 1 , wherein the ion blocker decreases a number of ions in a plasma to an amount less than or equal to 10%.
3 . The gas distribution apparatus of claim 1 , wherein the thickness of the ion blocker is in the range of 0.5 mm to 50 mm.
4 . The gas distribution apparatus of claim 3 , wherein the thickness of the ion blocker is in the range of 2 mm to 20 mm.
5 . The gas distribution apparatus of claim 1 , wherein voltage regulator is configured to provide a direct current (DC) polarization of the ion blocker relative to the showerhead in the range of about ±2V to about ±100V.
6 . The gas distribution apparatus of claim 1 , wherein the voltage regulator is configured to provide a direct current (DC) polarization of the ion blocker relative to the showerhead in the range of about ±5V to about ±50V.
7 . The gas distribution apparatus of claim 1 , wherein the openings in the ion blocker have a diameter in the range of about ⅛″ to about ½″.
8 . The gas distribution apparatus of claim 7 , wherein the openings in the ion blocker have a diameter in the range of ¼″ to ⅜″.
9 . The gas distribution apparatus of claim 1 , wherein the openings in the ion blocker are circular with a diameter in the range of 3 mm to 13 mm.
10 . The gas distribution apparatus of claim 1 , wherein at least some of the openings in the ion blocker are aligned with at least some of the openings in the showerhead.
11 . The gas distribution apparatus of claim 1 , wherein each of the openings in the ion blocker is aligned with one of the openings in the showerhead.
12 . A processing chamber comprising:
a remote plasma source having a plasma generation region connected to a gas distribution apparatus having an ion blocker and a showerhead with a gap between; and
a voltage regulator connected to the ion blocker and the showerhead, the voltage regulator configured to polarize the showerhead relative to the ion blocker to decrease a number of ions in a plasma generated by the remote plasma source from a first number to a second number, the second number less than or equal to 20% of the first number.
13 . The processing chamber of claim 12 , further comprising a substrate support having a support surface facing a front surface of the showerhead.
14 . The processing chamber of claim 13 , further comprising a controller having one or more configurations selected from a configuration to: rotate the substrate support around a central axis; provide a flow of gas into the remote plasma source; generate a plasma in the remote plasma source; provide a voltage differential between the ion blocker and the showerhead.
15 . The processing chamber of claim 12 , wherein the ion blocker has a thickness in the range of 0.5 mm to 50 mm.