Mask etch plasma reactor with cathode providing a uniform distribution of etch rate

• US 20080100222A1
• Filed: 10/30/2006
• Published: 05/01/2008
• Est. Priority Date: 10/30/2006
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Bivens, Darin, Kumar, Ajay, Chandrachood, Madhavi R., Lewington, Richard, Grimbergen, Michael N., Nguyen, Khiem K.
• Granted Patent: US 8,002,946 B2
• Time in Patent Office: Days
• US Class Current: 315/111.21
• CPC Class Codes: H01J 37/3255 Material
• CPC Class Codes: H01L 21/67069 for drying etching
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring
• CPC Class Codes: H01L 21/68742 characterised by a lifting arrangement, e.g. lift pins
• CPC Class Codes: H01L 21/68757 characterised by a coating or a hardness or a material
• CPC Class Codes: H01L 21/68785 characterised by the mechanical construction of the susceptor, stage or support

Abstract

A plasma reactor for etching a workpiece such as a rectangular or square mask, includes a vacuum chamber having a ceiling and a sidewall and a workpiece support pedestal within the chamber including a cathode having a surface for supporting a workpiece, the surface comprising plural respective zones, the respective zones of the surface being formed of respective materials of different electrical characteristics. The zones can be arranged concentrically relative to an axis of symmetry of the wafer support pedestal.

Claims

1. A plasma reactor for processing a workpiece, comprising:

a vacuum chamber having a ceiling and a sidewall;

a workpiece support pedestal within said chamber including a cathode having a surface for supporting a workpiece, said surface comprising plural respective zones, said respective zones of said surface being formed of respective materials of different electrical characteristics.

2. The apparatus of claim 1 wherein said zones are arranged concentrically relative to an axis of symmetry of said wafer support pedestal.

3. The apparatus of claim 2 wherein said zones comprise an inner zone and an annular outer zone, the material of said inner zone comprising a conductor and the material of said outer zone comprising an insulator.

4. The apparatus of claim 2 wherein said respective materials comprise insulator materials of different electrical permittivities.

5. The apparatus of claim 1 wherein said cathode comprises an aluminum piece having a top surface and said plural respective zones of said surface comprise respective inserts of the respective materials.

6. The apparatus of claim 5 wherein said respective inserts are concentric.

7. The apparatus of claim 5 wherein said respective inserts comprise a first insert formed of a conductive material and a second insert formed of a non-conductive material.

8. The apparatus of claim 5 wherein said respective inserts comprise respective materials of different electrical permittivities.

9. The apparatus of claim 7 wherein said first insert comprises a disk-shaped center insert and said second insert comprises an annular outer insert.

10. The apparatus of claim 1 wherein said cathode is formed of a first metal, said apparatus further comprising:

a facilities plate formed of said first metal, said cathode having a bottom surface and said facilities plate having a top surface facing the bottom surface of said cathode;

plural elongate fasteners formed of a second metal having a higher strength and different electrical property than said first metal, said plural elongate fasteners joining said cathode and said facilities plate together along a periphery of said cathode and facilities plate; and

a thin ring layer between said cathode and said facilities plate formed of said second metal and being located at the periphery of said cathode and facilities plate.

11. The apparatus of claim 10 further comprising:

a coating of a third metal on the periphery of said bottom surface of said cathode and a coating of said third metal on the periphery of said top surface of said facilities plate, said third metal having an electrical conductivity higher than the electrical conductivity of said first metal.

12. The apparatus of claim 10 further comprising:

an annular groove in one of (a) said top surface of said facilities plate, (b) said bottom surface of said cathode, said annular groove being located at the periphery thereof, and a conductive compressible gasket within said annular groove.

13. The apparatus of claim 10 wherein said first metal comprises aluminum and said second metal comprises titanium.

14. The apparatus of claim 10 wherein said fasteners are threaded fasteners.

15. The apparatus of claim 11 wherein said third metal comprises nickel.

16. The apparatus of claim 1 wherein said cathode in the form of a disk having a rectangular plateau, said top surface for supporting a workpiece being the top surface of said plateau, said disk and plateau being formed of said first metal, said plateau conforming generally to the shape of a mask.

17. The apparatus of claim 16 further comprising:

a ring surrounding said plateau and having a top ring surface that can form a contiguous flat surface with a workpiece that can be supported on said plateau, said ring comprising plural layers of different insulator materials.

18. The apparatus of claim 17 wherein said plural layers in said ring are selected to provide an electrical impedance that matches an electrical impedance through said plateau in the presence of said workpiece.

19. A wafer support pedestal for use in a plasma reactor, comprising:

a cathode formed of a first metal;

a facilities plate formed of said first metal, said cathode having a bottom surface and said facilities plate having a top surface facing the bottom surface of said cathode;

plural elongate fasteners formed of a second metal having a higher strength that said first metal, said plural elongate fasteners joining said cathode and said facilities plate together along a periphery of said cathode and facilities plate;

a thin ring layer between said cathode and said facilities plate formed of said second metal and being located at the periphery of said cathode and facilities plate;

a coating of a very high conductivity metal on the periphery of said bottom surface of said cathode and a coating of said very high conductivity metal on the periphery of said top surface of said facilities plate; and

an annular groove in one of (a) said top surface of said facilities plate, (b) said bottom surface of said cathode, said annular groove being located at the periphery thereof, and a conductive compressible gasket within said annular groove.

20. The wafer support pedestal of claim 19 further comprising respective concentric inserts of respective electrical characteristics on a top surface of said cathode.