Electroplating apparatus for tailored uniformity profile

• US 8,858,774 B2
• Filed: 04/03/2012
• Issued: 10/14/2014
• Est. Priority Date: 11/07/2008
• Status: Active Grant

• Current Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Original Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Inventors: Mayer, Steven T., Porter, David W., Buckalew, Bryan L., Rash, Robert
• Primary Examiner(s): Wilkins, III, Harry D
• Application Number:
  US13/438,443
• Publication Number:
  US 20120258408A1
• Time in Patent Office: 924 Days
• Field of Search: None
• US Class Current: 205/96
• 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 17/008 Current shielding devices
• CPC Class Codes: C25D 17/06 Suspending or supporting devices for articles to be coated
• CPC Class Codes: C25D 17/12 Shape or form C25D17/14 takes precedence
• CPC Class Codes: C25D 21/10 Agitating of electrolytes; Moving of racks
• CPC Class Codes: C25D 21/12 Process control or regulation controlling or regulating in general G05
• CPC Class Codes: C25D 5/04 Electroplating with moving electrodes
• CPC Class Codes: C25D 5/18 Electroplating using modulated, pulsed or reversing current
• 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
• CPC Class Codes: H01L 21/76873 for electroplating

Abstract

Methods of electroplating metal on a substrate while controlling azimuthal uniformity, include, in one aspect, providing the substrate to the electroplating apparatus configured for rotating the substrate during electroplating, and electroplating the metal on the substrate while rotating the substrate relative to a shield such that a selected portion of the substrate at a selected azimuthal position dwells in a shielded area for a different amount of time than a second portion of the substrate having the same average arc length and the same average radial position and residing at a different angular (azimuthal) position. For example, a semiconductor wafer substrate can be rotated during electroplating slower or faster, when the selected portion of the substrate passes through the shielded area.

Claims

1. An electroplating apparatus for electroplating a metal on a substrate, the apparatus comprising:

(a) a plating chamber configured to contain an electrolyte, and an anode;

(b) a substrate holder configured to hold the substrate;

(c) an auxiliary azimuthally asymmetric electrode housed in a separate chamber, wherein an exposure of plating current from the auxiliary electrode is through at least one channel that delivers current into a region of the plating chamber near the periphery of the substrate over an arc angle of less than about 120 degrees and

(d) a controller comprising program instructions for electroplating the metal on the substrate while rotating the substrate, and while providing power to the auxiliary azimuthally asymmetric electrode in correlation with the rotation of the substrate, such that the auxiliary azimuthally asymmetric electrode donates plating current to a first portion of the substrate at a selected azimuthal position of the substrate differently than to a second portion of the substrate having the same average arc length and the same average radial position and residing at a different angular azimuthal position.

2. The apparatus of claim 1, wherein the auxiliary azimuthally asymmetric electrode is C-shaped.

3. The apparatus of claim 1, wherein the auxiliary azimuthally asymmetric electrode is configured to be anodically biased and is configured to donate different amounts of plating current to different azimuthal positions of the substrate during electroplating.

4. The apparatus of claim 1, wherein the auxiliary azimuthally asymmetric electrode is configured to be both anodically and cathodically biased during electroplating, and is configured to divert plating current from a first azimuthal position on the substrate and to donate plating current to a second azimuthal position on the substrate.

5. The apparatus of claim 1, wherein the apparatus further comprises a shield, shielding the periphery of the substrate at all azimuthal positions, and wherein the auxiliary azimuthally asymmetric electrode is configured to be anodically biased at least during a portion of a time of a full rotation of the substrate, and is configured to donate current to the selected azimuthal position on the substrate.

6. The apparatus of claim 1, wherein the apparatus is configured such that a distance between the auxiliary azimuthally asymmetric electrode and the substrate in plating position is no greater than 20% of the radius of the substrate.

7. An electroplating apparatus for electroplating a metal on a substrate, the apparatus comprising:

(a) a plating chamber configured to contain an electrolyte and a shield;

(b) a substrate holder configured to hold the substrate; and

(c) a controller comprising program instructions for electroplating the metal on the substrate while rotating the substrate relative to the shield such that a selected portion of the substrate at a selected azimuthal position dwells in a shielded area for a different amount of time than a second portion of the substrate having the same average arc length and the same average radial position and residing at a different angular azimuthal position.

8. The apparatus of claim 7, wherein program instructions comprise instructions for rotating the substrate at a first speed when the selected portion of the substrate is less shielded, and at a second speed when the selected portion of the substrate is more shielded, wherein one full rotation of the substrate comprises a first period of rotation at the first speed and a second period of rotation at the second speed.

9. The apparatus of claim 8, wherein the second speed is lower than the first speed.

10. The apparatus of claim 7, wherein the electroplating apparatus further comprises an ionically resistive ionically permeable element having a flat surface that is configured to be substantially parallel to and separated from the plating face of the substrate by a distance of about 10 millimeters or less during electroplating, wherein the element has a plurality of non-communicating holes.

11. The apparatus of claim 10, wherein the shield is an azimuthally asymmetric shield eclipsing some of the holes of the flow-shaping element or wherein the shield is the ionically resistive ionically permeable element having an azimuthally asymmetric distribution of holes.

12. An electroplating apparatus for electroplating a metal on a substrate, the apparatus comprising:

(a) a plating chamber configured to contain an electrolyte, an anode, and an azimuthally asymmetric auxiliary electrode;

(b) a substrate holder configured to hold the substrate; and

(c) a controller comprising program instructions for electroplating the metal on the substrate while rotating the substrate, and while providing power to the auxiliary azimuthally asymmetric electrode in correlation with the rotation of the substrate, such that the auxiliary azimuthally asymmetric electrode diverts and/or donates plating current to a first portion of the substrate at a selected azimuthal position of the substrate differently than to a second portion of the substrate having the same average arc length and the same average radial position and residing at a different angular azimuthal position, further comprising program instructions for;

during electroplating rotating a shield having a generally annular body with a removed segment, wherein the shield is positioned in close proximity of the substrate, and wherein the rotation is not synchronized with the substrate rotation and wherein the rotation optimizes flow of electrolyte in the proximity of the substrate.

13. A method of electroplating a metal on a substrate while controlling azimuthal uniformity, the method comprising:

(a) providing the substrate into an electroplating apparatus configured for rotating the substrate during electroplating, while the substrate is held by a substrate holder, wherein the electroplating apparatus comprises a plating chamber configured for holding an anode, a shield and an electrolyte; and

(b) electroplating the metal on the substrate while rotating the substrate relative to the shield such that a selected portion of the substrate at a selected azimuthal position dwells in a shielded area for a different amount of time than a second portion of the substrate having the same average arc length and the same average radial position and residing at a different angular azimuthal position.

14. A method of electroplating a metal on a substrate while controlling azimuthal uniformity, the method comprising:

(a) providing the substrate into an electroplating apparatus configured for rotating the substrate during electroplating, while the substrate is held by a substrate holder, wherein the electroplating apparatus comprises;

(i) a plating chamber configured for holding an anode, and an electrolyte, and (ii) an auxiliary azimuthally asymmetric electrode housed in a separate chamber, wherein an exposure of plating current from the auxiliary electrode is through at least one channel that delivers current into a region of the plating chamber near the periphery of the substrate over an arc angle of less than about 120 degrees; and

(b) electroplating the metal on the substrate while rotating the substrate, and while providing power to the auxiliary azimuthally asymmetric electrode in correlation with the rotation of the substrate, such that the auxiliary azimuthally asymmetric electrode donates plating current to a first portion of the substrate at a selected azimuthal position of the substrate differently than to a second portion of the substrate having the same average arc length and the same average radial position and residing at a different angular azimuthal position.

15. A method of electroplating a metal on a substrate while controlling azimuthal uniformity, the method comprising:

(a) providing the substrate into an electroplating apparatus configured for rotating the substrate during electroplating, while the substrate is held by a substrate holder, wherein the electroplating apparatus comprises (i) a plating chamber configured for holding an anode, an auxiliary azimuthally asymmetric electrode and an electrolyte, and (ii) a shield having a generally annular body with a removed segment, wherein the shield is positioned in close proximity of the substrate; and

(b) electroplating the metal on the substrate while rotating the substrate, and while providing power to the auxiliary azimuthally asymmetric electrode in correlation with the rotation of the substrate, such that the auxiliary azimuthally asymmetric electrode diverts and/or donates plating current to a first portion of the substrate at a selected azimuthal position of the substrate differently than to a second portion of the substrate having the same average arc length and the same average radial position and residing at a different angular azimuthal position, further comprising rotating the shield during electroplating, wherein the rotation of the shield is not synchronized with the substrate rotation and wherein the rotation optimizes flow of electrolyte in the proximity of the substrate.