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

• US 8,002,946 B2
• Filed: 10/30/2006
• Issued: 08/23/2011
• 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.
• Primary Examiner(s): Gramaglia; Maureen
• Application Number:
  US11/589,337
• Publication Number:
  US 20080100222A1
• Time in Patent Office: 1,758 Days
• Field of Search: 156/345.43, 156/345.44, 156/345.45, 156/345.46, 156/345.47, 118/715, 118/722, 118/723.R, 118/723.E
• US Class Current: 156/345.51
• 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 rectangular-shaped workpiece, comprising:

a vacuum chamber having a ceiling and a cylindrical sidewall;

a workpiece support pedestal within said chamber including a cathode having a rectangular-shaped surface for supporting the rectangular-shaped workpiece, wherein said cathode comprises;

an inner disk-shaped member of a first electrical characteristic,

an intermediate annular member of a second electrical characteristic different from said first electrical characteristic, and having a circular inner boundary conforming with said inner disk-shaped member and a rectangular outer boundary congruent with a boundary of said rectangular support surface;

an outer annular member having a rectangular inner boundary conforming with said rectangular outer boundary of said intermediate annular member, and comprising two layers of respective third and fourth electrical characteristics surrounding said intermediate annular member;

wherein said first electrical characteristic corresponds to that of a metallic material, said second electrical characteristic corresponds to that of an insulator material, and said third and fourth electrical characteristics corresponds to those of different dielectric materials.

2. The reactor of claim 1 further comprising an RF bias generator coupled to said cathode, wherein said inner and intermediate members form a plateau, and wherein said third and fourth electrical characteristics provide an RF impedance at the frequency of said RF bias generator matching an RF impedance through said plateau in the presence of the workpiece.

3. 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.

4. The apparatus of claim 3 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.

5. The apparatus of claim 4 wherein said third metal comprises nickel.

6. The apparatus of claim 3 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.

7. The apparatus of claim 3 wherein said first metal comprises aluminum and said second metal comprises titanium.

8. The apparatus of claim 3 wherein said fasteners are threaded fasteners.

9. The apparatus of claim 3 wherein said cathode is in the form of a disk having a rectangular plateau, said plateau conforming generally to the shape of said rectangular-shaped workpiece.

10. The reactor of claim 1 wherein said outer annular member comprises an annular shelf adjacent said rectangular inner boundary positioned to underlie a peripheral portion of the rectangular-shaped workpiece, and a raised portion surrounding said shelf and providing a raised surface positioned to be co-planar with a top surface of the rectangular-shaped workpiece.

11. The reactor of claim 1 wherein said outer annular member comprises a top surface having a rectangular opening corresponding to a shape of the rectangular-shaped workpiece, said top surface being coplanar with a top surface of the rectangular workpiece whenever said rectangular-shaped workpiece is mounted on said cathode.