Electrochemical treatment of integrated circuit substrates using concentric anodes and variable field shaping elements

• US 20020195352A1
• Filed: 04/04/2002
• Published: 12/26/2002
• Est. Priority Date: 03/27/2000
• Status: Active Grant

• Current Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Original Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Inventors: Ponnuswamy, Thomas A., Janicki, Michael John, Cleary, Timothy Patrick, Mayer, Steven T., Minshall, Edmund B.
• Granted Patent: US 6,755,954 B2
• Time in Patent Office: Days
• US Class Current: 205/687
• CPC Class Codes: C25D 17/001 Apparatus specially adapted for electrolytic coating of wafers, e.g. semiconductors or solar cells
• CPC Class Codes: C25D 17/008 Current shielding devices
• CPC Class Codes: C25D 17/08 Supporting racks , i.e. not for suspending
• CPC Class Codes: C25D 17/12 Shape or form C25D17/14 takes precedence
• CPC Class Codes: C25D 7/123 Semiconductors first coated with a seed layer or a conductive layer
• CPC Class Codes: Y10S 204/07 Current distribution within the bath

Abstract

An apparatus for electrochemical treatment of a substrate, in particular for electroplating an integrated circuit wafer. An apparatus preferably includes dynamically operable concentric anodes and dielectric shields in an electrochemical bath. Preferably, the bath height of an electrochemical bath, the substrate height, and the shape and positions of an insert shield and a diffuser shield are dynamically variable during electrochemical treatment operations. Step include varying anode current, bath height and substrate height, shield shape, and shield position.

Claims

1. An apparatus for electrochemically treating a surface of a substrate, comprising:

a substrate holder;

a plurality of dynamically operable concentric anodes opposite said substrate holder;

a diffuser shield located between said substrate holder and said concentric anodes; and

an insert shield located between said diffuser shield and said substrate holder.

2. An apparatus as in claim 1, wherein:

said diffuser shield comprises an inside lip diameter in a range of about from 8 inches to 12 inches.

3. An apparatus as in claim 1, wherein:

said diffuser shield is a beta-type diffuser shield comprising wedge-shaped open areas in an annular lip.

4. An apparatus as in claim 1, wherein:

said insert shield comprises an inside diameter in a range of about from 10.5 to 12 inches.

5. An apparatus as in claim 1, wherein:

said insert shield and said substrate holder form a flow gap having a width in a range of about from 0.075 to 0.3 inches.

6. An apparatus as in claim 1, wherein:

said insert shield comprises a streamline-type rim portion.

7. An apparatus as in claim 1, wherein:

said insert shield comprises a modified streamline-type rim portion having a radius of curvature in a range of about from {fraction (1/16)} to one-half inch.

8. An apparatus for electrochemically treating a surface of a substrate, comprising:

a first bath container configured to retain an electrochemical bath at a bath height;

a plurality of dynamically operable concentric anodes disposed in said first bath container;

a substrate holder disposed in said first bath container opposite said concentric anodes at a substrate height;

a shield disposed in said first bath container between said concentric anodes and said substrate holder, said shield configured for shielding a surface area of a substrate when a substrate is held in said substrate holder during electrochemical treatment operations; and

a means, operable during electrochemical treatment operations, for dynamically varying a parameter selected from the group consisting of;

a quantity of shielded surface area of a substrate, a distance separating said shield from said substrate holder, a distance separating said substrate holder from said concentric anodes, and combinations thereof.

9. An apparatus as in claim 8, comprising:

a variable weir assembly for dynamically varying said bath height; and

an actuator for dynamically moving said substrate holder, to vary dynamically said substrate height.

10. An apparatus as in claim 9, wherein:

said first bath container has a first overflow height; and

further comprising;

a second bath container surrounding said first bath container and having a second overflow height higher than said first overflow height; and

a third, overflow container surrounding said second bath container.

11. An apparatus as in claim 10, further comprising:

a first valve for maintaining an electrochemical bath at said first overflow height; and

a second valve for maintaining an electrochemical bath at said second overflow height.

12. An apparatus as in claim 9, wherein:

said first bath container comprises a bath container wall; and

further comprising;

a movable sluice gate in said bath container wall for controlling said bath height.

13. An apparatus as in claim 8, wherein said shield is a diffuser shield located between said concentric anodes and said substrate holder.

14. An apparatus as in claim 13, wherein:

said diffuser shield comprises a plurality of rings rotatable about a common axis, each of said rings configured to have an open area and a closed area, and

an actuator for dynamically rotating one of said rings to vary a quantity of shielded surface area of a substrate.

15. An apparatus as in claim 8, wherein said shield is an insert shield located between said anode and said substrate holder.

16. An apparatus as in claim 15, wherein:

said insert shield is separated from said substrate holder by a flow gap.

17. An apparatus as in claim 16, further comprising:

a movable spacer for attaching said insert shield to said substrate holder; and

an actuator for moving said spacer to vary dynamically said flow gap.

18. An apparatus as in claim 8, further comprising:

means for rotating said substrate holder.

19. In an apparatus for electrochemically treating the surface of a substrate, comprising:

a bath container configured to retain an electrochemical bath having a bath height;

an anode disposed in said bath container;

a substrate holder opposite said anode and located at a substrate height;

a shield disposed between said anode and said substrate holder, said shield configured for shielding a surface area of a substrate when a substrate is held in said substrate holder; and

a means, operable during electrochemical treatment operations, for dynamically varying a parameter selected from a group including a quantity of shielded surface area of a substrate, a distance separating said shield from a substrate in said substrate holder, a distance separating said substrate holder from said anode, and combinations thereof, the improvement characterized by said means being selected from the group consisting of;

a variable weir assembly for dynamically varying said bath height and an actuator for dynamically moving said substrate holder, to vary dynamically said substrate height;

a shield comprising a plurality of rings rotatable about a common axis, each of said rings configured to have an open area and a closed area, and an actuator for rotating one of said rings to vary a quantity of shielded surface area of said substrate; and

a movable spacer for attaching a shield to said substrate holder and an actuator for moving said spacer to vary a distance separating said shield from said substrate.

20. In a method for electrochemically treating the surface of a substrate, comprising steps of:

providing an electrochemical bath with an anode located at the bottom of said electrochemical bath;

placing a wafer substrate in said substrate holder; and

then immersing said wafer substrate held in said substrate holder into said electrochemical bath opposite said anode;

the improvement characterized by a further step, prior to said step of immersing, said further step selected from the group consisting of;

pre-washing an electrical contact in said substrate holder, and pre-wetting said wafer substrate.

21. A method as in claim 20, further comprising a step of:

rotating said wafer substrate.

22. A method for electrochemically treating the surface of a substrate, comprising steps of:

providing an electrochemical bath with a plurality of concentric anodes located at the bottom of said electrochemical bath;

placing a wafer substrate in a substrate holder,

immersing said wafer substrate into said electrochemical bath at a substrate height and opposite said concentric anodes;

providing a diffuser shield located between said wafer substrate and said concentric anodes;

providing an insert shield located between said diffuser shield and said wafer substrate; and

dynamically varying the power delivered to said concentric anodes.

23. A method as in claim 22, further comprising a step of:

pre-washing electrical contacts located in said substrate holder before placing said wafer substrate in said substrate holder.

24. A method as in claim 22, further comprising a step of:

pre-wetting said wafer substrate before placing said wafer substrate in said substrate holder.

25. A method as in claim 22, further comprising a step of:

dynamically varying a flow gap between said insert shield and said substrate holder.

26. A method as in claim 22, further comprising a step of:

dynamically varying a closed area of said diffuser shield.

27. A method as in claim 22, further comprising steps of:

dynamically varying said bath height; and

dynamically varying said substrate height.

29. A method as in claim 28, comprising steps of:

dynamically varying said bath height; and

dynamically moving said substrate holder, to vary dynamically said substrate height.

30. A method as in claim 29, comprising steps of:

substantially closing a first outlet valve so that electrochemical fluid substantially fills a second bath container, thereby generating a second bath height; and

controlling a second valve in a third container to maintain said second bath height.

31. A method as in claim 28, comprising a step of:

dynamically moving said substrate holder to vary said substrate height, thereby actuating a movable sluice gate in a bath container wall of said bath container for controlling said bath height.

32. A method as in claim 28, wherein said shield is a diffuser shield comprising a plurality of rings rotatable about a common axis, each of said rings configured to have an open area and a closed area, and said diffuser shield is located between said concentric anodes and said substrate holder, and further comprising a step of:

dynamically rotating one of said rings to vary a quantity of shielded surface area of a substrate.

33. A method as in claim 28, wherein said shield is an insert shield attached to said substrate holder by a movable spacer and located between said anode and said substrate holder, and further comprising steps of:

actuating said movable spacer to vary dynamically a flow gap between said insert shield and said substrate holder.

34. A method as in claim 28, further comprising a step of:

pre-washing an electrical contact in said substrate holder before said step of immersing.

35. A method as in claim 28, further comprising a step of:

pre-wetting said wafer substrate before said step of immersing.

36. A method as in claim 28, further comprising:

rotating said substrate holder.

38. A method as in claim 37, comprising steps of:

substantially closing a first outlet valve so that electrochemical fluid substantially fills a second bath container, thereby generating a second bath height; and

controlling a second valve in a third container to maintain said second bath height.

39. A method as in claim 37, comprising a step of:

dynamically moving said substrate holder to vary said substrate height, thereby actuating a movable sluice gate in a bath container wall for controlling said bath height.

28. A method for electrochemically treating a surface of a substrate, comprising steps of:

providing an electrochemical bath having a bath height in a first bath container, said first bath container containing a plurality of dynamically operable concentric anodes in a bottom portion of said first bath container, and further containing a shield located above said concentric anodes;

immersing a wafer substrate held in a substrate holder into said electrochemical bath at a substrate height, such that said wafer substrate is opposite said concentric anodes and said shield is between said wafer substrate and said concentric anodes; and

dynamically varying a parameter selected from the group consisting of;

a quantity of shielded surface area of said substrate, a distance separating said shield from said substrate, a distance separating said substrate from said concentric anodes, and combinations thereof.

37. In a method for electrochemically treating the surface of a substrate, comprising steps of dynamically varying a parameter from a group including a quantity of shielded surface area of a substrate, a distance separating a shield from a substrate, a distance separating a substrate holder from an anode, and combinations thereof, the improvement comprising steps selected from the group consisting of:

dynamically varying a bath height, and dynamically moving a substrate holder, to vary dynamically a substrate height;

dynamically rotating a ring of a shield to vary a quantity of shielded surface area of a substrate, wherein said shield is a diffuser shield comprising a plurality of rings rotatable about a common axis, each of said rings configured to have an open area and a closed area; and

actuating a movable spacer to vary dynamically a flow gap between an insert shield and a substrate holder.