Clamshell apparatus for electrochemically treating wafers

• US 6,800,187 B1
• Filed: 08/10/2001
• Issued: 10/05/2004
• Est. Priority Date: 05/31/2001
• Status: Expired due to Fees

• Current Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Original Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Inventors: Stowell, R. Marshall, Hawkins, Jeff A., Reid, Jonathan D., Mayer, Steven T., Patton, Evan E.
• Primary Examiner(s): Nicolas, Wesley A.
• Application Number:
  US09/927,741
• Time in Patent Office: 1,152 Days
• Field of Search: 205/118, 205/133, 205/148, 204/224.R, 204/275.1, 427/98, 427/304
• US Class Current: 205/118
• CPC Class Codes: C23C 18/1619 Apparatus for electroless plating
• CPC Class Codes: C23C 18/1628 Specific elements or parts of the apparatus
• CPC Class Codes: C23C 18/163 Supporting devices for articles to be coated
• CPC Class Codes: C23C 18/1669 Agitation, e.g. air introduction
• CPC Class Codes: C25D 17/001 Apparatus specially adapted for electrolytic coating of wafers, e.g. semiconductors or solar cells
• CPC Class Codes: C25D 17/004 Sealing devices
• CPC Class Codes: C25D 17/008 Current shielding devices
• CPC Class Codes: C25D 5/08 Electroplating with moving electrolyte e.g. jet electroplating using locally applied jets of electrolyte C25D5/026
• CPC Class Codes: C25D 7/123 Semiconductors first coated with a seed layer or a conductive layer
• CPC Class Codes: H01L 21/2885 using an external electrical current, i.e. electro-deposition

Abstract

An apparatus for engaging a work piece during plating facilitates electrolyte flow during a plating operation. The apparatus helps to control the plating solution fluid dynamics and electric field shape to keep the wafer'"'"'s local plating environment uniform and bubble free. The apparatus holding the work piece in a manner that facilitates electrolyte circulation patterns in which the electrolyte flows from the center of the work piece plating surface, outward toward the edge of the edge of the work piece. The apparatus holds the work piece near the work piece edges and provides a flow path for electrolyte to flow outward away from the edges of the work piece plating surface. That flow path has a “snorkel” shape in which the outlet is higher than the inlet. In addition, the flow path may have a slot shape that spans much or all of the circumference of holding apparatus. It may be made from a material that resists deformation and corrosion such as certain ceramics.

Claims

1. An apparatus for engaging a work piece during plating, the apparatus comprising:

a cup having a circumferential side wall defining an interior region and a lip within the interior region arranged such that lip can support the work piece while the work piece remains within the interior region;

a field shaping element shaped and sized to affect an electric field shape impinging on the work piece during plating, the field shaping element designed for connection with the cup;

a flow path defining a passage for plating fluid to flow from inside the apparatus to outside the apparatus, said flow path residing in a region between the field shaping region and the cup and having an inlet on the inside of the apparatus and proximate the cup'"'"'s lip and an outlet on the outside of the apparatus and positioned such that the outlet is at a higher elevation than the inlet when the apparatus oriented for use with the cup above the field shaping element; and

a cone having a work piece contact surface that fits within the cup'"'"'s interior and can contact the work piece in a manner that holds the work piece in a fixed position against the cup'"'"'s lip.

2. The apparatus of claim 1, wherein the cup'"'"'s lip is sized and shaped to support a semiconductor wafer work piece.

3. The apparatus of claim 2, wherein the cup'"'"'s lip comprises a lipseal made from a material that provides a fluid tight seal with the semiconductor wafer when the wafer is held in place by the cone.

4. The apparatus of claim 3, wherein the lipseal material is an elastomer.

5. The apparatus of claim 1, wherein at least a portion of the cup facing the inside of the apparatus is made from a material selected from the group consisting of a ceramic, plastic-coated ceramic, plastic-coated metal, glasses, glass-coated metals, and composites.

6. The apparatus of claim 5, wherein a plastic used in the coating of the plastic-coated ceramic or metal is a fluoropolymer.

7. The apparatus of claim 5, wherein the ceramic or a ceramic used in the plastic-coated ceramic is alumina or zirconia.

8. The apparatus of claim 1, further comprising one or more actuators for moving the work piece into and out of the plating fluid, while the work piece is held in position by the cup and cone.

9. The apparatus of claim 8, wherein the one or more actuators can pivot the work piece about an axis defined on or proximate the work piece.

10. The apparatus of claim 1, wherein the cup and the field shaping element together form a unitary element.

11. The apparatus of claim 1, wherein the cup and the field shaping element are separate elements held in fixed positions with respect to one another by a fastener.

12. The apparatus of claim 11, wherein the fastener allows a separation distance between the cup and field shaping element to be adjusted to thereby adjust a dimension of the flow path.

13. The apparatus of claim 1, wherein said flow path has a slot shape that is substantially coextensive with the cup'"'"'s circumferential side wall.

14. The apparatus of claim 1, wherein said flow path has a hole shape.

15. The apparatus of claim 14, further comprising additional hole shaped flow paths distributed about the cup'"'"'s circumferential side wall.

16. The apparatus of claim 14, wherein the inlet to the flow path has a grooved channel.

17. The apparatus of claim 14, wherein the cup and cone are configured to hold the work piece in a workpiece plane, and wherein the flow path is angled at an offset angle measured in the workpiece plane from a radial vector from a center line inside the apparatus toward the outside of the apparatus.

18. The apparatus of claim 1, wherein a portion of the cup separating the lipseal from the flow path has a thickness of between about 0.25 and 2.0 millimeters.

19. The apparatus of claim 1, wherein a portion of the cup separating the lipseal from the flow path has a thickness of between about 0.5 and 1.25 millimeters.

20. The apparatus of claim 1, wherein the flow path length is between about 30 and 60 millimeters.

21. The apparatus of claim 1, wherein the flow path length is between about 35 and 50 millimeters.

22. The apparatus of claim 17, wherein the offset angle is between about 25 and 50 degrees.

23. The apparatus of claim 17, wherein the offset angle is about 45 degrees.

24. A method of plating a material onto a work piece, the method comprising:

holding the work piece between a cone and a cup of an apparatus, wherein the cup has a circumferential side wall defining an interior region and a lip within the interior region and supporting the work piece while the work piece remains within the interior region, and wherein the cone has a work piece contact surface that fits within the cup'"'"'s interior and contacts the work piece in a manner that holds the work piece in a fixed position against the cup'"'"'s lip;

immersing the work piece in the plating fluid prior to plating, wherein the work piece has a substantially flat plating surface and wherein the holding step comprises holding the substantially flat plating surface in an orientation that is not parallel to a plane defined by a plating fluid surface; and

while plating, directing a plating fluid through a flow path defining a passage for the plating fluid to flow from inside the apparatus to outside the apparatus, said flow path defined by the cup and the field shaping element, having an inlet on the inside of the apparatus and an outlet on the outside of the apparatus and positioned such that the outlet is at a higher elevation than the inlet, whereby gas present in a portion of the plating fluid in the flow path travels toward the outlet due to its buoyancy.

25. The method of claim 24, further comprising directing the plating fluid toward a substantially flat plating surface of the work piece, thereby setting up a circulation pattern in which the plating fluid flows along the plating surface and through the flow path.

26. The method of claim 24, further comprising rotating the work piece about an axis substantially parallel to the circumferential side-wall.

27. The method of claim 24, wherein work piece is a semiconductor wafer.

28. The method of claim 27, wherein the work piece is positioned on a lipseal of the lip to thereby provide a fluid tight seal with the semiconductor wafer when the wafer is held in place by the cone.

29. The method of claim 24, wherein at least a portion of the cup facing the inside of the apparatus is made from a material selected from the group consisting of a ceramic, plastic-coated ceramic, plastic-coated metal, and composites.

30. The method of claim 24, further comprising fastening the cup to a field shaping element together at a specified separation distance to thereby define a dimension of the flow path.

31. The method of claim 30, further comprising adjusting the separation distance to thereby adjust the dimension of the flow path.

32. The method of claim 24, wherein said flow path has a slot shape that is substantially coextensive with the cup'"'"'s circumferential side wall.

33. The method of claim 24, wherein said flow path has a hole shape.

34. The method of claim 33, further comprising additional hole shaped flow paths distributed about the cup'"'"'s circumferential side wall.

35. The method of claim 33, wherein the inlet to the flow path has a grooved channel.

36. The method of claim 33, wherein the fixed position of the holding step defines a workpiece plane and wherein the flow path is angled at an offset angle measured in the workpiece plane from a radial vector from a center line inside the apparatus toward the outside of the apparatus.

37. The method of claim 24, wherein the plating fluid is an electrolyte and electroplating is the method of plating.

38. The method of claim 24, wherein the plating fluid contains metal ions and electroless plating is the method of plating.

39. An apparatus for engaging a work piece during plating, the apparatus comprising:

a cup having a circumferential side wall defining an interior region and a lip within the interior region arranged such that lip can support the work piece in a first plane while the work piece remains within the interior region, the cup having a first surface defined in part by a thickness of the lip, at least a portion of the first surface being curved and substantially non-parallel to the first plane;

a field shaping element shaped and sized to affect an electric field shape impinging on the work piece during plating, the field shaping element having a second surface substantially in conformity with the first surface, thereby defining a flow path between the first surface and the second surface and forming a passage for plating fluid to flow from inside the apparatus to outside the apparatus, said flow path having an inlet on the inside of the apparatus and proximate the cup'"'"'s lip and an outlet on the outside of the apparatus and positioned such that the outlet is at a higher elevation than the inlet when the apparatus oriented for use with the cup above the field shaping element; and

a cone having a work piece contact surface that fits within the cup'"'"'s interior and configured to contact the work piece in a manner that holds the work piece in a fixed position against the cup'"'"'s lip.

40. An apparatus for engaging a work piece during plating, the apparatus comprising:

a cup having a circumferential side wall defining an interior region and a lip within the interior region arranged such that lip can support the work piece in a first plane while the work piece remains within the interior region;

a field shaping element shaped and sized to affect an electric field shape impinging on the work piece during plating, the field shaping element defining a snorkel-shaped flow path between the field-shaping element and the cup, forming a passage for plating fluid to flow from inside the apparatus to outside the apparatus, said snorkel-shaped flow path having an inlet on the inside of the apparatus proximate the cup'"'"'s lip and an outlet on the outside of the apparatus and positioned such that the outlet is at a higher elevation than the inlet when the apparatus oriented for use with the cup above the field shaping element; and

a cone having a work piece contact surface that fits within the cup'"'"'s interior and configured to contact the work piece in a manner that holds the work piece in a fixed position against the cup'"'"'s lip.

41. An apparatus for engaging a work piece during plating, the apparatus comprising:

a cup having a circumferential side wall defining an interior region and a lip within the interior region arranged such that lip can support the work piece in a first plane while the work piece remains within the interior region, the cup comprising a plurality of flow holes disposed below the lip, the plurality of flow holes shaped and sized to affect an electric field shape impinging on the work piece during plating, the plurality of flow holes defining a plurality of flow paths for plating fluid to flow from inside the apparatus to outside the apparatus, each of the flow paths having an inlet on the inside of the apparatus and proximate the cup'"'"'s lip and an outlet on the outside of the apparatus and positioned such that the outlet is at a higher elevation than the inlet when the apparatus oriented for use; and

a cone having a work piece contact surface that fits within the cup'"'"'s interior and can contact the work piece in a manner that holds the work piece in a fixed position against the cup'"'"'s lip.

42. The apparatus of claim 41, wherein the plurality of flow holes define snorkel-shaped flow paths.

43. The apparatus of claim 41, wherein the fixed position defines a workpiece plane and wherein the plurality of flow holes are offset from a radial direction of the cup, the offset measured in a plane parallel to the workpiece plane.

44. The apparatus of claim 41, wherein the plurality of flow holes comprise a grooved inlet.

45. The apparatus of claim 43, wherein the offset is between about 25 degrees to 50 degrees.