Method and apparatus for electroplating semiconductor wafer when controlling cations in electrolyte

Patent metadata

Field	Value
Publication number	US-9816196-B2
Application number	US-201313869891-A
Country	US
Kind code	B2
Filing date	Apr 24, 2013
Priority date	Apr 27, 2012
Publication date	Nov 14, 2017
Grant date	Nov 14, 2017

Abstract

Apparatus and methods for electroplating metal onto substrates are disclosed. The electroplating apparatus comprise an electroplating cell and at least one oxidization device. The electroplating cell comprises a cathode chamber and an anode chamber separated by a porous barrier that allows metal cations to pass through but prevents organic particles from crossing. The oxidation device (ODD) is configured to oxidize cations of the metal to be electroplated onto the substrate, which cations are present in the anolyte during electroplating. In some embodiments, the ODD is implemented as a carbon anode that removes Cu(I) from the anolyte electrochemically. In other embodiments, the ODD is implemented as an oxygenation device (OGD) or an impressed current cathodic protection anode (ICCP anode), both of which increase oxygen concentration in anolyte solutions. Methods for efficient electroplating are also disclosed.

First claim

What is claimed is:

1. An apparatus for electroplating a metal onto a substrate, the apparatus comprising:
(a) an electroplating cell comprising:
a cathode chamber for containing catholyte during electroplating;
a cathode electrical connection in the cathode chamber, the cathode electrical connection being able to connect to the substrate and apply a potential allowing the substrate to become a cathode;
an anode chamber for containing anolyte during electroplating;
an anode electrical connection in the anode chamber, the anode electrical connection being able to connect to an electroplating anode and apply a potential to the electroplating anode; and
a porous transport barrier placed between the anode chamber and the cathode chamber, which transport barrier enables migration of ionic species in an electrolyte, including metal cations, across the transport barrier while substantially preventing organic additives from passing across the transport barrier;

(b) at least one oxygenation device (OGD) configured to oxidize cations of the metal to be electroplated onto the substrate, which cations are present in the anolyte during electroplating; and
(c) an oxygen concentration meter configured to measure oxygen concentration in the anolyte.

2. The apparatus of claim 1 , wherein the metal to be electroplated onto the substrate is copper, the anolyte comprises one or more copper salts dissolved in a solvent, and the oxygenation device (OGD) oxidizes Cu(I) to Cu(II).

3. The apparatus of claim 2 , wherein the catholyte contains a substantially greater concentration of the organic plating additives than the anolyte does.

4. The apparatus of claim 2 , wherein the porous transport barrier comprises a material selected from the group consisting of porous glasses, porous ceramics, silica areogels, organic aerogels, porous polymeric materials, and filter membranes.

5. The apparatus of claim 2 , further comprising an anolyte recirculation loop fluidically coupled to the electroplating cell, wherein the anolyte recirculation loop comprises an anolyte storage reservoir connected to the anode chamber, and an anolyte recirculation pump that recirculates anolyte to the anode chamber.

6. The apparatus of claim 5 , wherein the oxygenation device (OGD) is disposed in the anolyte recirculation loop and exposes anolyte in the anolyte recirculation loop to oxygen.

7. The apparatus of claim 6 , wherein the OGD is placed in line with the anolyte recirculation pump.

8. The apparatus of claim 6 , wherein the OGD comprises a dwell tank fluidly coupled to the anode chamber.

9. The apparatus of claim 6 , wherein the OGD comprises an oxygen sparging device disposed in the anolyte storage reservoir.

10. The apparatus of claim 6 , wherein the OGD comprises a contactor or a membrane contactor.

11. The apparatus of claim 6 , wherein the anolyte recirculation loop is configured to operate with a flow rate at about 0.25 liters per minute (lpm) to about 1 lpm.

12. The apparatus of claim 6 , wherein a source of oxygen for the OGD is selected from the group consisting of atmospheric air, clean dry air, substantially pure oxygen, and combinations thereof.

13. The apparatus of claim 6 , wherein the oxygen concentration meter provides a real-time oxygen concentration reading to a controller that is configured for controlling an oxygen concentration in the anolyte within a desired range during an electroplating process.

14. The apparatus of claim 1 , further comprising a catholyte storage reservoir connected to the cathode chamber to provide a catholyte to the cathode chamber.

15. The apparatus of claim 1 , wherein the apparatus further comprises:
(d) a controller configured to operate the OGD so as to increase a dissolved oxygen concentration of the anolyte to greater than 0.05 parts per million (PPM) but no more than 4 PPM.

16. The apparatus of claim 15 , wherein the controller is configured to operate the OGD to increase a dissolved oxygen concentration of the anolyte to greater than 0.05 PPM but no more than 2 PPM.

17. The apparatus of claim 15 , wherein the controller is configured to operate the OGD to increase a dissolved oxygen concentration of the anolyte to greater than 0.5 PPM but no more than 4 PPM.

18. The apparatus of claim 15 , wherein the controller is configured to operate the OGD to increase a dissolved oxygen concentration of the anolyte to greater than 0.5 PPM but no more than 2 PPM.

19. The apparatus of claim 15 , wherein the controller is configured to operate the OGD to increase a dissolved oxygen concentration of the anolyte to greater than 0.05 PPM but no more than 1 PPM.

Assignees

• Novellus Systems Inc

Inventors

• Spurlin Tighe A
• Merrill Charles L
• Huang Ludan
• Thorum Matthew
• Brogan Lee
• Duncan James E
• Wilmot Frederick D
• Stowell Robert Marshall
• Mayer Steven T
• Fu Haiying
• Porter David W
• Ghongadi Shantinath
• Reid Jonathan D
• Lee Hyosang S
• Willey Mark J

Classifications

• C25D3/38

  of copper · CPC title

• C25D21/14 Primary

  Controlled addition of electrolyte components · CPC title

• C25D21/12

  Process control or regulation (controlling or regulating in general G05) · CPC title

• C25D17/001

  Apparatus specially adapted for electrolytic coating of wafers, e.g. semiconductors or solar cells · CPC title

• C25D17/002 Primary

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