Dynamic current distribution control apparatus and method for wafer electroplating

Patent metadata

Field	Value
Publication number	US-10023970-B2
Application number	US-201715787580-A
Country	US
Kind code	B2
Filing date	Oct 18, 2017
Priority date	Aug 16, 2006
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

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, an ionically resistive ionically permeable element positioned between a substrate and the anode chamber during electroplating, an auxiliary cathode located between the anode and the ionically resistive ionically permeable element, and an insulating shield with an opening in its central region. The insulating shield may be movable with respect to the ionically resistive ionically permeable element to vary a distance between the shield and the ionically resistive ionically permeable element during electroplating.

First claim

What is claimed is:

1. 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, a shield, and an anode chamber housing an anode, the plating chamber containing the anode chamber, the shield oriented between the anode and an ionically resistive ionically permeable element, wherein the shield comprises an opening in a central region of the shield, wherein the shield includes an outer perimeter and an inner perimeter, the inner perimeter of the shield defining the opening, and wherein a surface of the shield includes a slope such that the outer perimeter is closer to the ionically resistive ionically permeable element than the inner perimeter;
(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) supplying current to an auxiliary cathode located between the anode and the ionically resistive ionically permeable element to thereby shape a current distribution from the anode.

2. The method of claim 1 , further comprising supplying current to a secondary 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.

3. The method of claim 1 , further comprising
moving the shield 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, and dynamically controlling the position of the shield during plating to account for a
reduction of a voltage decrease from an edge to a center of the surface of the substrate.

4. The method of claim 1 , wherein the plating chamber further includes a cationic membrane separating the plating chamber into an anolyte chamber and a catholyte chamber, wherein the anode resides in the anolyte chamber.

5. The method of claim 1 , wherein an area of the opening in the shield is about 15% to 80% of an area of the surface of the substrate.

6. The method of claim 1 , further comprising moving the shield 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, 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 shield is in the first position.

7. The method of claim 1 , further comprising
moving the shield 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, wherein the shield moves from the first position to the second position in a period of time.

8. The method of claim 1 , 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.

9. The method of claim 1 , wherein the ionically resistive ionically permeable element has a plurality of non-communicating perforations and wherein ions in the electrolyte solution pass through the perforations.

10. The method of claim 1 , wherein the auxiliary cathode is a virtual auxiliary cathode having an associated physical cathode housed in a cavity in the plating chamber, wherein the cavity is in ionic communication with the plating chamber.

11. The method of claim 1 , further comprising dynamically controlling an amount of current supplied to the auxiliary cathode during plating to account for a reduction of non-uniform current distribution at the surface of the substrate.

12. The method of claim 1 , wherein when current is initially supplied to the auxiliary cathode in (d), a ratio of current supplied to the auxiliary cathode and to the substrate is at least about 4:1.

13. The method of claim 1 , wherein a maximum current supplied to the auxiliary cathode during electroplating is between about 5 to 40 Amps.

14. The method of claim 2 , wherein a maximum current supplied to the secondary auxiliary cathode during electroplating is between about 5 to 25 Amps.

15. The method of claim 2 , wherein a ratio of current supplied to the auxiliary cathode and the secondary auxiliary cathode during electroplating ranges between about 2:1 and 10:1.

16. The method of claim 9 , wherein substantially all perforations have a principal dimension or a diameter no greater than about 5 millimeters, wherein the principal dimension or diameter is measured on a side of the ionically resistive ionically permeable element that faces the surface of the substrate.

17. The method of claim 11 , wherein no current or substantially no current is supplied to the auxiliary cathode after:
(i) a sheet resistance of the substrate surface reaches about 2 to 5 ohm/square or less,
(ii) at least about 100 to 250 angstroms of metal are plated during (c) or
(iii) metal is plated during (c) for a period of about 2 to 6 seconds or less.

Assignees

• Novellus Systems Inc

Inventors

• He Zhian
• Porter David W
• Reid Jonathan D
• Wilmot Frederick D

Classifications

• H10P14/40

  of conductive or resistive materials · CPC title

• C25D17/06

  Suspending or supporting devices for articles to be coated · CPC title

• C25D17/002

  Cell separation, e.g. membranes, diaphragms · CPC title

• C25D17/10

  Electrodes {, e.g. composition, counter electrode} · CPC title

• C25D7/123

  Semiconductors first coated with a seed layer or a conductive layer · CPC title