Configuration and method of operation of an electrodeposition system for improved process stability and performance

Patent metadata

Field	Value
Publication number	US-10745817-B2
Application number	US-201715785333-A
Country	US
Kind code	B2
Filing date	Oct 16, 2017
Priority date	Jan 7, 2011
Publication date	Aug 18, 2020
Grant date	Aug 18, 2020

Abstract

In one aspect, an apparatus includes a plating cell, a degassing device configured to remove oxygen from the plating solution prior to the plating solution flowing into the plating cell; an oxidation station configured to increase an oxidizing strength of the plating solution after the plating solution flows out of the plating cell; and a controller. The controller includes program instructions for causing a process that includes operations of: reducing an oxygen concentration of the plating solution where the plating solution contains a plating accelerator; then, contacting a wafer substrate with the plating solution having reduced oxygen concentration and electroplating a metal such that the electroplating causes a net conversion of the accelerator to a less-oxidized accelerator species within the plating cell; then increasing the oxidizing strength of the plating solution causing a net re-conversion of the less-oxidized accelerator species back to the accelerator outside the plating cell.

First claim

What is claimed is:

1. An apparatus for electroplating a metal, comprising:
(a) a plating cell, the plating cell being configured to hold a plating solution;
(b) a degassing device coupled to the plating cell, the degassing device being configured to remove oxygen from the plating solution prior to the plating solution flowing into the plating cell;
(c) an oxidation station coupled to the plating cell, the oxidation station being configured to increase an oxidizing strength of the plating solution after the plating solution flows out of the plating cell; and
(d) a controller comprising program instructions for causing a process comprising the operations of:
(i) reducing an oxygen concentration of the plating solution using the degassing device, wherein the plating solution includes about 100 parts per million or less of an accelerator;
(ii) after operation (i), contacting, in the plating cell, a wafer substrate with the plating solution, wherein the oxygen concentration of the plating solution in the plating cell is about 1 part per million or less;
(iii) electroplating a metal with the plating solution onto the wafer substrate in the plating cell, wherein the electroplating causes a net conversion of the accelerator to a less-oxidized accelerator species within the plating cell; and
(iv) after operation (iii), increasing the oxidizing strength of the plating solution outside the plating cell using the oxidation station by controlling the level of active oxygenation of the plating solution, wherein the increased oxidizing strength causes a net re-conversion of the less-oxidized accelerator species back to the accelerator outside the plating cell.

2. The apparatus of claim 1 , wherein the degassing device is coupled to the oxidation station, and the apparatus further comprises:
an electrolyte flow loop configured to circulate the plating solution through the apparatus.

3. The apparatus of claim 1 , wherein the oxidation station is configured to increase a gas contact area of the plating solution.

4. The apparatus of claim 1 , further comprising a plating reservoir fluidically connected with the plating cell.

5. The apparatus of claim 4 , wherein the process further comprises the operation of supplying the plating solution to the plating cell from the plating reservoir, wherein the oxygen concentration of the plating solution in the plating reservoir is 2-5 parts per million, and wherein reducing the oxygen concentration of the plating solution is performed as the plating solution is supplied from the plating reservoir.

6. The apparatus of claim 1 , wherein operation (iv) includes exposing the plating solution to a gas containing an oxidizing agent, and wherein the gas is selected from the group consisting of air, oxygen, ozone, and nitrous oxide.

7. The apparatus of claim 1 , wherein operation (iv) includes exposing the plating solution to a gas containing an oxidizing agent by bubbling the gas through the plating solution, and wherein the gas is selected from the group consisting of air, oxygen, ozone, and nitrous oxide.

8. The apparatus of claim 1 , wherein operation (iv) includes exposing the plating solution to a gas containing an oxidizing agent while increasing the gas contact area of the plating solution, and wherein the gas is selected from the group consisting of air, oxygen, ozone, and nitrous oxide.

9. The apparatus of claim 1 , wherein operation (iv) includes mixing a liquid containing an oxidizing agent into the plating solution.

10. The apparatus of claim 9 , wherein the liquid includes hydrogen peroxide.

11. The apparatus of claim 1 , wherein operation (i) comprises sparging the plating solution using helium or nitrogen.

12. The apparatus of claim 1 , wherein operation (i) improves the stability of the plating solution.

13. The apparatus of claim 1 , wherein operation (iv) improves the fill characteristics of the plating solution for filling a feature on the wafer substrate.

14. The apparatus of claim 1 , wherein the process further comprises operations of:
applying photoresist to the wafer substrate;
exposing the photoresist to light;
patterning the photoresist and transferring the pattern to the wafer substrate; and
selectively removing the photoresist from the wafer substrate.

15. The apparatus of claim 1 , wherein the process further comprises an operation of:
monitoring an oxygen concentration of the plating solution;

wherein, in operation (iv), the controller comprises program instructions for causing an adjustment of the level of active oxygenation of the plating solution in response to said monitored oxygen concentration.

16. The apparatus of claim 1 , wherein, in operation (iv), the level of active oxygenation is adjusted to increase an oxygen concentration of the plating solution outside the plating cell to 2-5 parts per million.

17. The apparatus of claim 1 , wherein, in operation (iv), the level of active oxygenation of the plating solution is controlled by introducing an oxidizing agent into the plating solution.

18. The apparatus of claim 1 , wherein the accelerator is bis (3-sulfopropyl) disulfide (SPS), and the less-oxidized accelerator species is mercaptopropanesulfonic acid (MPS).

19. The apparatus of claim 1 , wherein the process further comprises: repeating operations (i) and (iv), wherein the plating solution flows through the plating cell while operation (iii) is performed.

Assignees

• Novellus Systems Inc

Inventors

• Ganesan Kousik
• Spurlin Tighe A
• Reid Jonathan David
• Ghongadi Shantinath
• Mckerrow Andrew John
• Duncan James E

Classifications

• C25D21/14 Primary

  Controlled addition of electrolyte components · CPC title

• C25D5/003

  Electroplating using gases, e.g. pressure influence · CPC title

• C25D21/04

  Removal of gases or vapours {; Gas or pressure control} · CPC title

• C25D7/123

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

• C25D5/08

  Electroplating with moving electrolyte e.g. jet electroplating {(using locally applied jets of electrolyte C25D5/026)} · CPC title