Method and apparatus for plasma processing
In an embodiment, a plasma processing system includes a vacuum chamber, a substrate holder configured to hold a substrate to be processed where the substrate holder is disposed in the vacuum chamber. The system further includes an electron source disposed above a peripheral region of the substrate holder, the electron source being configured to generate an electron beam towards the peripheral region of the substrate holder.
1. A plasma processing system, comprising:
a plasma processing chamber configured to contain a direct plasma generated in the plasma processing chamber;
a substrate holder disposed in the plasma processing chamber and configured to hold a substrate to be processed, the substrate being in contact with the direct plasma; and
an electron beam source disposed above and vertically aligned with a peripheral region of the substrate and the substrate holder surrounding a central region of the substrate and the substrate holder,
wherein the electron beam source is configured to generate an electron beam from the direct plasma, the electron beam comprising ballistic electrons traveling in a direction perpendicular to the peripheral region, and
wherein the electron beam impinges on the peripheral region and not on the central region of the substrate and the substrate holder, the ballistic electrons stimulating chemical reactions at the substrate.
2. The system of claim 1 , wherein the electron beam source comprises an edge electrode coupled to a direct current (DC) supply node.
3. The system of claim 2 , wherein a ratio of an inside radius of the edge electrode to a width of the edge electrode varies between 10:1 to 150:1.
4. The system of claim 2 , wherein surfaces of the edge electrode that are exposed to the direct plasma are covered by a dielectric material.
5. The system of claim 4 , wherein the edge electrode further comprises a first conductive region arranged in an annular shape and coupled to the DC supply node through a first contact, and an outer surface configured to be exposed to a plasma of the plasma processing system and configured to generate the electron beam.
6. The system of claim 5 , further comprising:
a central electrode disposed above the central region, the central electrode disposed within the edge electrode.
7. The system of claim 6 , wherein the central electrode comprises a second conductive region distributed along or within the central electrode, a second contact for a DC source or an alternating current (AC) power source, the second contact being coupled to the second conductive region, the second contact being electrically isolated from the first contact.
8. The system of claim 7 , wherein a diameter of the central electrode is larger than a thickness of the central electrode.
9. The system of claim 7 , wherein the second conductive region comprises a doped semiconductor material.
10. The system of claim 2 , further comprising a central electrode disposed above the central region, the central electrode disposed within the edge electrode.
11. The system of claim 10 , wherein the central electrode comprises doped semiconductor material.
12. The system of claim 1 , wherein the system is configured to generate plasma within the plasma processing chamber using an inductive process or a capacitive process.
13. The system of claim 1 , wherein the electron beam source comprises an outlet configured to be coupled to an external source of electrons.
14. The system of claim 1 , wherein the electron beam impinges on substantially the entire peripheral region.
15. The system of claim 14 , wherein a width of the substrate included in the peripheral region is less than about 10 percent of a total width of the substrate.
16. A plasma processing system comprising:
an edge electrode portion disposed around and electrically isolated from a central portion, the edge electrode portion being further disposed above and vertically aligned with a peripheral region of a substrate holder, wherein the edge electrode portion comprises
an inner diameter greater than the diameter of the central portion,
a thickness less than the inner diameter,
a first conductive region disposed between the inner diameter and an outer diameter and configured to generate ballistic electrons traveling in a direction perpendicular to the peripheral region from a direct plasma of the plasma processing system,
a first electrical coupling component for coupling a direct-current (DC) power supply to the first conductive region, and
an outer surface configured to be exposed to the direct plasma and covering the first conductive region, the outer surface comprising a dielectric material: and
a central electrode portion disposed in the central portion, the central electrode portion comprising
a second conductive region distributed along or within the central electrode portion,
a second electrical coupling component for coupling an alternating current (AC) power source, the second electrical coupling component being coupled to the second conductive region, and
a diameter that is larger than a thickness of the central electrode portion, wherein the second electrical coupling component is electrically isolated from the first electrical coupling component.
17. The system of claim 16 , wherein the second electrical coupling component is configured to couple both a direct current (DC) source and the alternating current (AC) power source.
18. The system of claim 17 , wherein the second conductive region comprises a doped semiconductor material.
19. A plasma processing system, comprising:
a vacuum chamber configured to contain a direct plasma generated in the vacuum chamber;
a substrate holder disposed in the vacuum chamber and configured to hold a substrate to be processed, the substrate being in contact with the direct plasma;
an electron beam source disposed above and vertically aligned with a peripheral region of the substrate and the substrate holder surrounding a central region of the substrate and the substrate holder, the electron beam source being configured to generate an electron beam from the direct plasma, the electron beam comprising ballistic electrons traveling towards the peripheral region, the electron beam source comprising an edge electrode arranged in an annular shape coupled to a first direct current (DC) supply node;
a central electrode disposed within the annular shape of the edge electrode above the central region, the central electrode being electrically isolated from the edge electrode; and
a dielectric material encasing both the electron beam source and the central electrode.
20. The system of claim 19 , wherein the central electrode comprises doped semiconductor material.
21. The system of claim 19 , wherein the edge electrode is coplanar with and electrically isolated from the central electrode.
22. The system of claim 19 , wherein the central electrode is coupled to both a second direct current (DC) supply node and an alternating current (AC) supply node.