DYNAMIC CURRENT DISTRIBUTION CONTROL APPARATUS AND METHOD FOR WAFER ELECTROPLATING

• US 20130134045A1
• Filed: 11/29/2011
• Published: 05/30/2013
• Est. Priority Date: 11/29/2011
• Status: Active Grant

• Current Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Original Assignee: David W. Porter, Frederick D. Wilmot, Jonathan D. Reid
• Inventors: PORTER, David W., REID, Jonathan D., WILMOT, Frederick D.
• Granted Patent: US 9,045,840 B2
• Time in Patent Office: Days
• US Class Current: 205/158
• CPC Class Codes: C25D 17/001 Apparatus specially adapted for electrolytic coating of wafers, e.g. semiconductors or solar cells
• CPC Class Codes: C25D 17/002 Cell separation, e.g. membranes, diaphragms
• CPC Class Codes: C25D 17/007 Current directing devices
• CPC Class Codes: C25D 17/06 Suspending or supporting devices for articles to be coated
• CPC Class Codes: C25D 17/10 Electrodes , e.g. composition, counter electrode
• CPC Class Codes: C25D 17/12 Shape or form C25D17/14 takes precedence
• CPC Class Codes: C25D 21/12 Process control or regulation controlling or regulating in general G05

Abstract

Methods, systems, and apparatus for plating a metal onto a work piece are described. In one aspect, an apparatus includes a plating chamber, a substrate holder, an anode chamber housing an anode, and an ionically resistive ionically permeable element positioned between a substrate and the anode chamber during electroplating. The anode chamber may be movable with respect to the ionically resistive ionically permeable element to vary a distance between the anode chamber and the ionically resistive ionically permeable element during electroplating. The anode chamber may include an insulating shield oriented between the anode and the ionically resistive ionically permeable element, with opening in a central region of the insulating shield.

Claims

1. An apparatus comprising:

(a) a plating chamber configured to contain an electrolyte while electroplating metal onto a substrate;

(b) a substrate holder configured to hold the substrate and having one or more electrical power contacts arranged to contact an edge of the substrate and to provide electrical current to the substrate during electroplating;

(c) an ionically resistive ionically permeable element positioned between the substrate and an anode chamber during electroplating, the ionically resistive ionically permeable element having a flat surface that is substantially parallel to and separated from a plating face of the substrate; and

(d) the anode chamber housing an anode, the anode chamber being movable with respect to the ionically resistive ionically permeable element to vary a distance between the anode chamber and the ionically resistive ionically permeable element during electroplating, the anode chamber including an insulating shield oriented between the anode and the ionically resistive ionically permeable element with an opening in a central region of the insulating shield.

2. The apparatus of claim 1, wherein the anode chamber includes a cationic membrane in the opening in the insulating shield that separates the anode chamber from a catholyte chamber, wherein the catholyte chamber includes a volume of the plating chamber not occupied by the anode chamber.

3. The apparatus of claim 1, further comprising:

a cationic membrane separating the plating chamber into an anolyte chamber and a catholyte chamber, wherein the anode chamber resides in the anolyte chamber.

4. The apparatus of claim 1, wherein an area of the opening in the insulating shield is about 10% to 30% of an area of the plating face of the substrate.

5. The apparatus of claim 1, wherein the insulating shield includes an outer perimeter and an inner perimeter, the inner perimeter of the insulating shield defining the opening, and wherein a surface of the insulating shield includes a slope such that the outer perimeter is closer to the ionically resistive ionically permeable element than the inner perimeter.

6. The apparatus of claim 5, wherein positions of the anode chamber include an upper position, and wherein when the anode chamber is in the upper position, the outer perimeter is about 1 millimeter to 10 millimeters from the ionically resistive ionically permeable element and the inner perimeter is about 3 millimeters to 50 millimeters from the ionically resistive ionically permeable element.

7. The apparatus of claim 1, wherein the insulating shield includes an outer perimeter and an inner perimeter, the inner perimeter of the insulating shield defining the opening, and wherein the outer perimeter is about the same distance from the ionically resistive ionically permeable element as the inner perimeter.

8. The apparatus of claim 1, wherein the distance between the anode chamber and the ionically resistive ionically permeable element may be varied by about 2 centimeters to 20 centimeters.

9. The apparatus of claim 1, wherein the ionically resistive ionically permeable element has an ionically resistive body with a plurality of perforations made in the body such that the perforations do not form communicating channels within the body, wherein said perforations allow for transport of ions through the element, and wherein substantially all of the perforations have a principal dimension or a diameter of the opening on the surface of the element facing the surface of the substrate of no greater than about 5 millimeters.

10. The apparatus of claim 1, wherein the flat surface of the ionically resistive ionically permeable element is separated from the plating face of the substrate by a gap of about 1 millimeter to 8 millimeters during electroplating.

11. The apparatus of claim 1, further comprising an auxiliary cathode located in substantially the same plane as the substrate during electroplating, and adapted for diverting a portion of ionic current from an edge region of the substrate.

12. The apparatus of claim 11, wherein the auxiliary cathode is located peripheral to the substrate holder and radially outward of a peripheral gap between the ionically resistive ionically permeable element and the substrate holder.

13. The apparatus of claim 1, further comprising:

a control circuit designed or configured to control the distance between the anode chamber and the ionically resistive ionically permeable element in a manner that produces a uniform current distribution from the anode at the plating face of the substrate.

14. The apparatus of claim 1, further comprising:

a control circuit designed or configured to position the anode chamber at a first distance from the ionically resistive ionically permeable element when electroplating the metal begins, and to move the anode chamber to a second distance from the ionically resistive ionically permeable element as the metal is electroplated onto the substrate, the first distance being less than the second distance.

15. The apparatus of claim 14, wherein a distance between the first distance and the second distance is about 2 centimeters to about 20 centimeters.

16. The apparatus of claim 1, further comprising:

a control circuit designed or configured to position the anode chamber at an upper position when a sheet resistance of the substrate is about 50 Ohms per square to 5 Ohms per square.

17. The apparatus of claim 1, further comprising:

a control circuit designed or configured to linearly move the anode chamber with time as the metal is electroplated onto the substrate.

18. The apparatus of claim 1, further comprising:

a controller comprising program instructions for conducting a process comprising the operations of;

(a) immersing the plating face of the substrate held in the substrate holder in the electrolyte, the substrate having a conductive seed and/or barrier layer disposed on the plating face;

(b) supplying current to the substrate to plate the metal onto the seed and/or barrier layer; and

(c) moving the anode chamber from a first position to a second position, the second position being located a distance further away from the ionically resistive ionically permeable element than the first position.

19. A system comprising the apparatus of claim 1 and a stepper.

20. An apparatus comprising:

(a) a plating chamber configured to contain an electrolyte and an anode while electroplating metal onto a substrate;

(b) a substrate holder configured to hold the substrate such that a plating face of the substrate is positioned at a distance from the anode during electroplating, the substrate holder having one or more electrical power contacts arranged to contact an edge of the substrate and to provide electrical current to the substrate during electroplating;

(c) an ionically resistive ionically permeable element positioned between the substrate and the anode, the ionically resistive ionically permeable element having a flat surface that is substantially parallel to and separated from the plating face of the substrate; and

(d) a first insulating disk and a second insulating disk positioned between the ionically resistive ionically permeable element and the anode, the first and the second insulating disks being movable with respect to the ionically resistive ionically permeable element to vary a distance between the disks and the ionically resistive ionically permeable element during electroplating, the first and the second insulating disks including an opening in the central region of each disk.

21. The apparatus of claim 20, wherein the first and the second insulating disks further include a plurality of holes in each disk, the plurality of holes in the first insulating disk being offset from the plurality of holes in the second insulating disk such that when the first and the second disks are positioned at a first position relative to one another, substantially no electrolyte can flow though the plurality of holes in each disk, and when the first and the second disks are positioned at a second position relative to one another, electrolyte can flow through the plurality of holes in each disk.

22. The apparatus of claim 21, wherein distances between the first and the second insulating disks and the ionically resistive ionically permeable element include a first distance and a second distance, wherein at the first distance, the disks are closer to the ionically resistive ionically permeable element than at the second distance.

23. The apparatus of claim 22, wherein the disks are positioned at the first position relative to one another at the first distance, and wherein the disks are positioned at the second position relative to one another at the second distance.

24. The apparatus of claim 20, wherein an area of the openings in the first and the second insulating disks is about 10% to 30% of an area the plating face of the substrate.

25. The apparatus of claim 20, wherein the first position and the second position of the first and the second insulating disks differ by a distance between the disks.

26. The apparatus of claim 20, wherein the first position and the second position of the first and the second insulating disks differ by a rotation of the first insulating disk relative to the second insulating disk.

27. The apparatus of claim 20, further comprising:

a cationic membrane separating the plating chamber into an anolyte chamber and a catholyte chamber, wherein the first and the second insulating disks reside in the anolyte chamber.

28. The apparatus of claim 20, further comprising:

a control circuit designed or configured to control the distance between the first and the second insulating disks and the ionically resistive ionically permeable element in a manner that produces a uniform current distribution from the anode at the plating face of the substrate.

29. The apparatus of claim 20, further comprising:

a control circuit designed or configured to position the first and the second insulating disks at a first distance from the ionically resistive ionically permeable element when electroplating the metal begins, and to move the disks to a second distance from the ionically resistive ionically permeable element as the metal is electroplated onto the substrate, the first distance being less than the second distance.

30. The apparatus of claim 29, wherein a distance between the first distance and the second distance is about 5 centimeters to 15 centimeters.

31. A method comprising:

(a) holding a substrate having a conductive seed and/or barrier layer disposed on its surface in a substrate holder of an apparatus, the apparatus including a plating chamber and an anode chamber housing an anode, the plating chamber containing the anode chamber, the anode chamber including an insulating shield oriented between the anode and an ionically resistive ionically permeable element with an opening in a central region of the insulating shield;

(b) immersing the surface of the substrate in an electrolyte solution and proximate the ionically resistive ionically permeable element positioned between the surface and the anode chamber, the ionically resistive ionically permeable element having a flat surface that is parallel to and separated from the surface of the substrate;

(c) supplying current to the substrate to plate a metal layer onto the seed and/or barrier layer; and

(d) moving the anode chamber from a first position to a second position, the second position being located a distance further away from the ionically resistive ionically permeable element than the first position.

32. The method of claim 31, further comprising dynamically controlling the position of the anode chamber during plating to account for a reduction of a voltage decrease from an edge to a center of the surface of the substrate.

33. The method of claim 31, wherein the anode chamber includes a cationic membrane in the opening in the insulating shield that separates the anode chamber from a catholyte chamber, wherein the catholyte chamber includes a volume of the plating chamber not occupied by the anode chamber.

34. The method of claim 31, wherein the plating chamber further includes a cationic membrane separating the plating chamber into an anolyte chamber and a catholyte chamber, wherein the anode chamber resides in the anolyte chamber.

35. The method of claim 31, wherein an area of the opening in the insulating shield is about 10% to 30% of an area of the surface of the substrate.

36. The method of claim 31, wherein a sheet resistance of the substrate having a conductive seed and/or barrier is about 50 Ohms per square to 5 Ohms per square when the anode chamber is in the first position.

37. The method of claim 31, wherein the anode chamber linearly moves from the first position to the second position in a period of time.

38. The method of claim 31, further comprising:

supplying current to an auxiliary cathode located in substantially the same plane as the substrate and thereby diverting a portion of ionic current from an edge region of the substrate.

39. The method of claim 31, further comprising:

applying photoresist to the substrate;

exposing the photoresist to light;

patterning the photoresist and transferring the pattern to the substrate; and

selectively removing the photoresist from the substrate.

40. A non-transitory computer machine-readable medium comprising program instructions for control of an apparatus, the instructions comprising code for:

(a) holding a substrate having a conductive seed and/or barrier layer disposed on its surface in a substrate holder of an apparatus, the apparatus including a plating chamber and an anode chamber housing an anode, the plating chamber containing the anode chamber, the anode chamber including an insulating shield oriented between the anode and an ionically resistive ionically permeable element with an opening in a central region of the insulating shield;

(b) immersing the surface of the substrate in an electrolyte solution and proximate the ionically resistive ionically permeable element positioned between the surface and the anode chamber, the ionically resistive ionically permeable element having a flat surface that is parallel to and separated from the surface of the substrate;

(c) supplying current to the substrate to plate a metal layer onto the seed and/or barrier layer; and

(d) moving the anode chamber from a first position to a second position, the second position being located a distance further away from the ionically resistive ionically permeable element than the first position.