Purge and pumping structures arranged beneath substrate plane to reduce defects

1. A substrate processing system comprising:

a processing chamber including a top surface, a bottom surface and side walls;

a substrate support arranged in the processing chamber to support a substrate during processing; and

a purge structure arranged in the processing chamber below a plane occupied by the substrate during processing,

wherein the purge structure includes a body sealed against a bottom surface of the substrate support to define a plenum between the purge structure and the bottom surface of the substrate support, wherein the plenum is configured to receive purge gas supplied from below the substrate support, and

wherein the purge structure includes a first plurality of holes formed in the body and configured to supply the purge gas from the plenum to purge an area between the substrate support and the bottom surface of the processing chamber, wherein the plurality of holes is distributed along different radial distances on a bottom surface of the body.

2. The substrate processing system of claim 1 , wherein the first plurality of holes directs purge gas in a downwardly direction towards the bottom surface of the processing chamber.

3. The substrate processing system of claim 1 , wherein the first plurality of holes directs purge gas in a downwardly and radially outwardly direction.

4. The substrate processing system of claim 1 , wherein the purge structure is connected to the bottom surface of the substrate support.

5. The substrate processing system of claim 1 , wherein the purge structure includes an elongate member that is attached to the bottom surface of the substrate support.

6. The substrate processing system of claim 1 , wherein the substrate support includes a central supporting member connecting the substrate support to the bottom surface of the processing chamber.

7. The substrate processing system of claim 6 , further comprising a pumping structure arranged below the substrate support and around the central supporting member, wherein the pumping structure includes a second plurality of holes for controlling flow from the processing chamber through the pumping structure.

8. The substrate processing system of claim 7 , wherein the pumping structure includes:

a first portion arranged around the central supporting member; and

a second portion connected to the first portion and extending from the first portion to the side walls of the processing chamber, wherein the second plurality of holes of the pumping structure is arranged at spaced locations on the second portion.

9. The substrate processing system of claim 8 , wherein the first portion has a cylindrical shape and the second portion is planar.

10. The substrate processing system of claim 9 , wherein the planar portion has a cross-section to mate with a bottom portion of the processing chamber and to define a first volume in fluid communication with a reaction zone and second volume in fluid communication with vacuum and wherein the first plurality of holes fluidly connects the first volume with the second volume.

11. The substrate processing system of claim 1 , further comprising a heater to heat the purge structure to a predetermined temperature.

12. The substrate processing system of claim 7 , further comprising a heater to heat the pumping structure to a predetermined temperature.

13. A substrate processing system comprising:

a processing chamber including a top surface, a bottom surface and side walls;

a substrate support arranged in the processing chamber to support a substrate during processing, wherein the substrate support includes a central supporting member connecting the substrate support to the bottom surface of the processing chamber;

a purge structure including a body sealed against a bottom surface of the substrate support to define a plenum between the purge structure and the bottom surface of the substrate support, wherein the plenum is configured to receive purge gas supplied from below the substrate support, and

a pumping structure arranged in the processing chamber below the substrate support and around the central supporting member, wherein the pumping structure includes a first plurality of holes to control flow from the processing chamber through the pumping structure,

wherein the purge structure includes a second plurality of holes configured to flow the purge gas from the plenum through the second plurality of holes to purge an area between the substrate support and the bottom surface of the processing chamber, wherein the second plurality of holes is distributed along different radial distances on a bottom surface of the body.

14. The substrate processing system of claim 13 , wherein the pumping structure includes:

a first portion arranged around the central supporting member; and

a second portion connected to the first portion and extending from the first portion to the side walls of the processing chamber, wherein the first plurality of holes of the pumping structure is arranged at spaced locations on the second portion.

15. The substrate processing system of claim 14 , wherein the first portion has a cylindrical shape and the second portion is planar.

16. The substrate processing system of claim 13 , wherein the planar portion has a cross-section to mate with a bottom portion of the processing chamber and to define a first volume in fluid communication with a reaction zone and second volume in fluid communication with vacuum and wherein the first plurality of holes fluidly connect the first volume with the second volume.

17. The substrate processing system of claim 13 , further comprising a heater to heat the pumping structure to a predetermined temperature.