Variable quadruple electromagnet array in plasma processing

• US 7,527,713 B2
• Filed: 09/23/2004
• Issued: 05/05/2009
• Est. Priority Date: 05/26/2004
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Gung, Tza-Jing, Perrin, Mark A., Gillard, Andrew
• Primary Examiner(s): Neckel; Alexa D
• Assistant Examiner(s): BAND, MICHAEL A
• Application Number:
  US10/950,349
• Publication Number:
  US 20050263389A1
• Time in Patent Office: 1,685 Days
• Field of Search: 118/723.I, 118/723.MR, 156/345.38, 204/298.06, 204/298.31, 315/111.41, 315/111.51, 427/571, 438/711, 438/732
• US Class Current: 204/192.12
• CPC Class Codes: H01J 37/32688 Multi-cusp fields
• CPC Class Codes: H01J 37/3408 Planar magnetron sputtering

Abstract

A quadruple electromagnetic coil array coaxially arranged in a rectangular array about a chamber axis outside the sidewalls of a plasma sputter reactor, preferably in back of an RF coil within the chamber. The coil currents can be separately controlled to produce different magnetic field distributions, for example, between a sputter deposition mode in which the sputter target is powered to sputter target material onto a wafer and a sputter etch mode in which the RF coil supports the gas sputtering the wafer. The coil array may include a tubular magnetic core, particularly useful for suppressing stray fields. A water cooling coil may be wrapped around the coil array to cool all the coils. The electromagnets can be powered in different relative polarities in a multi-step process.

Claims

1. In a plasma sputter reactor having a substrate support disposed in a plane perpendicular to a central axis of a vacuum chamber having sidewalls formed around the central axis and a sputter target arranged in opposition to the substrate support across a space along the central axis, an array of four separately controllable electromagnet coils arranged about said central axis in a rectangular array at axial positions along the central axis between the sputter target and the substrate support and all being configured to be connected to at least one DC power supply, at least two of the coils being disposed at different radii from the central axis and at least two of the coils being disposed at different axial positions relative to the central axis.

2. The array of claim 1, wherein two of said coils located closer to said substrate support have at least 50% more turns than radially corresponding ones of two of said coils located farther away from said substrate support.

3. The array of claim 1, further comprising a magnetic core disposed between at least some of said four coils.

4. The array of claim 1, incorporated into an adapter forming a portion of said chamber between said target and said substrate support.

5. The array of claim 1, further comprising a multi-wrap cooling coil thermally contacting at least two of said coils.

6. The array of claim 1, wherein currents in said at least some of said four coils circulate in opposite directions about said central axis.

7. The array of claim 6, wherein said levels of said currents are chosen to reduce stray fields outside of said chamber.

8. A quadruple array comprising four electromagnet coils arranged in an annularly extending two-dimensional annular rectangular array in an assembly annular about an axis in a rectangular pattern and configured for being disposed outside and around the wall of a plasma sputter reactor having a sputter target in opposition along the axis to a holder for a substrate to be processed wherein at least two of the electromagnet coils are disposed at different radii from a central axis of the annular array and at least two of the electromagnet coils are disposed at different axial positions relative to the central axis and all of the electromagnet coils are axially disposed between the sputter target and the holder.

9. The array of claim 8, further comprising a magnetic core disposed between radially inner ones of said coils and radially outer ones of said coils.

10. The array of claim 9, wherein all of said coils are separated from each other within said assembly to allow magnetic field to form therebetween.

11. The array of claim 8, further comprising a single helically wound fluid cooling coil in thermal contact with said four electromagnet coils.

12. The array of claim 8, wherein all of said coils are separated from each other within said assembly to allow magnetic field to form therebetween.

13. The array of claim 8, further comprising an adapter around which said electromagnet coils are wound and configured to form part of a vacuum chamber of said plasma processing reactor.

20. The array of claim 8, wherein the electromagnet coils are configured to be connected to a plurality of DC power supplies.

14. A plasma sputter reactor, comprising:

a chamber body arranged generally symmetrically about a central axis;

a support for supporting within said chamber body a substrate to be plasma processed on a front face thereof;

a sputter target fixed to the chamber body arranged in opposite to the support along the central axis;

a rectangular array of four electromagnets wound about said chamber body at least two radii from said central axis and at least two axial distances displaced above said front face and below the sputter target, at least some of said electromagnets being independently powerable; and

a plurality of DC power supplies connected to the four electromagnets.

15. The sputter reactor of claim 14, further comprising a terminal structure including eight accessible and reconfigurable electrical connections to opposed ends of said four electromagnets.

16. The sputter reactor of claim 14, further comprising an RF coil disposed to overlap said array along said central axis.

17. A method of operating a plasma sputter reactor including a chamber arranged around a central axis, a substrate support for supporting a substrate to be processed, a sputter target in opposition to the substrate support along the central axis, and a rectangular array of four of electromagnet coils respectively positioned at two different raddi from the central axis and at two different axial positions along the central axis between the sputter target and the substrate support and wound around said central axis in a vicinity of said chamber, said method comprising the steps of:

a first step including passing co-rotating DC currents through two of said coils to process said substrate; and

a second step including passing counter-rotating DC currents through said two coils to process said substrate.

18. The method of claim 17, wherein at least one of said steps includes sputter depositing a material of said target onto said substrate.

19. The method of claim 17, wherein a third step includes passing counter-rotating DC currents through upper and lower ones of said coils and a fourth step includes passing counter-rotating DC currents through inner and outer ones of said coils.