Plasma processing apparatus

• US 5,439,524 A
• Filed: 04/05/1993
• Issued: 08/08/1995
• Est. Priority Date: 04/05/1993
• Status: Expired due to Fees

• Current Assignee: VLSI Technology, Inc. (Koninklijke Philips N.V.)
• Original Assignee: VLSI Technology, Inc. (Koninklijke Philips N.V.)
• Inventors: Cain, John L., Costabile, Michael E., Marsh, William P., Relue, Michael P.
• Primary Examiner(s): Kunemund, Robert
• Assistant Examiner(s): BASKIN, JONATHAN
• Application Number:
  US08/042,921
• Time in Patent Office: 855 Days
• Field of Search: 118/723 E, 118/723 ER, 118/715, 156/345, 156/643
• US Class Current: 118/723.00E
• CPC Class Codes: C23C 16/45565 Shower nozzles
• CPC Class Codes: C23C 16/4585 Devices at or outside the perimeter of the substrate support, e.g. clamping rings, shrouds
• CPC Class Codes: C23C 16/509 using internal electrodes
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/32449 Gas control, e.g. control of the gas flow

Abstract

An improved fluid distribution head for a plasma processing system characterized by a non-planar dispersion plate provided with a plurality of apertures formed therethrough, and a mechanism for flowing a process gas through the apertures of the dispersion plate. The non-planar dispersion plate is preferably provided with a concave, spherical portion having a radius of curvature of at least four feet. The mechanism for flowing the process gas through the apertures includes an enclosure defining a chamber which communicates with the dispersion plate, a gas inlet communicating with the chamber, and a source of process gas coupled to the gas inlet. The fluid distribution head preferably forms a part of a complete plasma processing system including a wafer pedestal and an R.F. generator coupled to the pedestal to form a plasma between the dispersion plate and the wafer from the process gas flowing from the dispersion plate. A method for processing a semiconductor wafer includes the steps of clamping a wafer to a pedestal (thereby imposing a curvature on the wafer) and releasing a process fluid over the wafer through a plurality of apertures provided in a non-planar dispersion plate having a complementary curvature to the curvature of the wafer.

Claims

1. A fluid distribution head for a plasma processing system for processing a workpiece surface having a convex section, the fluid distribution head comprising:

an enclosure section;

a gas inlet communicating with said enclosure section;

a source of process gas coupled to said gas inlet; and

a non-planar dispersion plate attached to said enclosure section such that said enclosure section and said dispersion plate cooperate to form a chamber, said dispersion plate being provided with a plurality of apertures formed therethrough to permit a flow of said process gas onto said workpiece surface having said convex section, said dispersion plate having a concave section which provides an even distribution of said process gas over said workpiece surface;

wherein said concave section of said dispersion plate is a concave, spherical section and wherein said convex section of said workpiece is a convex, spherical section.

2. A fluid distribution head as recited in claim 1 wherein said enclosure section comprises:

a back plate coupled to said gas inlet; and

sidewalls coupling said back plate to said dispersion plate;

whereby said dispersion plate is attached to said sidewalls opposite said backplate to form said chamber.

3. A fluid distribution head as recited in claim 1 wherein said concave, spherical section of said dispersion plate has a first spherical radius of curvature and wherein said convex, spherical section of said workpiece surface has a second spherical radius of curvature.

4. A fluid dispersion head as recited in claim 3 wherein said first spherical radius of curvature is about the same as said second spherical radius of curvature.

5. A fluid distribution head as recited in claim 3 wherein said first spherical radius of curvature is less than said second spherical radius of curvature.

6. A fluid distribution head as recited in claim 3 wherein said first spherical radius of curvature is greater than said second spherical radius of curvature.

7. A fluid distribution head as recited in claim 3 wherein said concave spherical section of said dispersion plate has a radius of curvature of at least four feet.

8. A fluid distribution head as recited in claim 3 wherein said concave spherical section of said dispersion plate has a radius of curvature of at most fifteen feet.

9. A fluid distribution head as recited in claim 1 further comprising:

an internal baffle residing within said chamber for increasing a flow of process gas from peripheral portions of said dispersion plate.

10. A plasma processing system comprising:

a pedestal to support a workpiece on a convex surface thereof;

a gas distribution head disposed proximate to said pedestal, said gas distribution head including a dispersion plate having a concave surface, said dispersion plate being provided with a plurality of apertures formed therethrough;

a gas supply system coupled to said fluid distribution head to provide a flow of process gas through said apertures; and

an R.F. generator coupled to said pedestal to form a plasma between said pedestal and said dispersion plate with said process gas;

wherein said pedestal comprises a cathode of said plasma processing system, and wherein said convex surface of said pedestal and said concave surface of said dispersion plate are spherical sections.

11. A plasma processing system as recited in claim 10 wherein said pedestal is provided with a clamp for securing a workpiece to said convex, spherical surface.

12. A plasma processing system as recited in claim 11 wherein said gas distribution head comprises an enclosure section attached to said dispersion plate to define a chamber.

13. A plasma processing system as recited in claim 12 wherein said gas supply system comprises:

a source of process gas; and

a conduit coupling said source of process gas to said chamber of said gas distribution head.

14. A plasma processing system as recited in claim 13 wherein said R.F. generator is further coupled to said dispersion plate, which serves as an anode for said plasma processing system.