Substrate susceptor using edge purging
A workpiece susceptor body can include a front face configured to support a workpiece, a back face opposite the front face, a workpiece contact zone at least partially forming a support boundary on an inner portion of the front face, and a plurality of axial channels disposed within the susceptor body. The workpiece contact zone can be disposed radially inward of an outer edge of a workpiece positioned on the front face in a processing configuration. Each of the plurality of axial channels may connect to corresponding openings extending into an outer portion of the front face. Each of the openings may be disposed radially outward of the workpiece contact zone of the susceptor body.
1. A method for purging a workpiece susceptor, the method comprising:
loading a workpiece onto a workpiece contact zone on a front face of a susceptor body, such that an outer edge of the workpiece is disposed radially outward from the workpiece contact zone, wherein the workpiece contact zone is substantially annular, and wherein loading the workpiece onto the workpiece contact zone comprises loading the workpiece radially inward of a workpiece retaining portion of the susceptor body positioned radially outward from the workpiece contact zone, the workpiece retaining portion configured to retain the workpiece;
positioning the workpiece in a processing configuration wherein the front face of the susceptor body is in fluid communication with a reaction chamber and wherein a back face of the susceptor body is in fluid communication with a loading chamber;
providing a first pressure within the reaction chamber; and
purging a backside of the outer edge of the workpiece by flowing purge gas at a second pressure from one or more channels within the susceptor body, to a gap radially outward of the workpiece contact zone and axially between the front face of the susceptor plate and the workpiece, to the reaction chamber, wherein the second pressure is greater than the first pressure.
2. The method of claim 1 , wherein the one or more channels comprises one or more axial channels, wherein purging the backside of the outer edge of the workpiece comprises flowing the purge gas through the one or more axial channels disposed within the susceptor body, wherein the one or more axial channels extend through the workpiece susceptor body and the back face.
3. The method of claim 1 , wherein the purge gas comprises an inert gas and a reactive gas.
4. The method of claim 3 , wherein the inert gas comprises argon and the reactive gas comprises hydrogen.
5. The method of claim 1 , wherein loading the workpiece onto the workpiece contact zone comprises loading the workpiece at a greater elevation than an outer portion of the front face to form the gap radially outward of the workpiece contact zone and axially between the front face of the susceptor body and the workpiece.
6. The method of claim 1 , wherein the workpiece retaining portion is positioned radially outward from openings within the susceptor that are in fluid communication with the one or more channels.
7. The method of claim 6 , wherein loading the workpiece onto the workpiece contact zone comprises supporting the workpiece on the workpiece contact zone at a lower elevation than the workpiece retaining portion.
8. The method of claim 1 , wherein the one or more channels comprises a plurality of radial channels and a plurality of axial channels, wherein purging the backside of the outer edge of the workpiece comprises flowing the purge gas through the plurality of radial channels positioned between the front face and the back face, and wherein the plurality of radial channels extend from and are in fluid communication with at least one of the plurality of axial channels.
9. The method of claim 8 , further comprising evacuating gas between the workpiece and the susceptor via at least one longitudinal vacuum channel extending through a pedestal configured to support the back face.
10. The method of claim 9 , wherein evacuating the gas between the workpiece and the susceptor comprises evacuating the gas via one or more apertures extending into an inner portion of the front face.
11. The method of claim 1 , further comprising receiving a thermal reading via a thermocouple disposed within at least one radial thermocouple channel positioned between the front face and the back face.