Control of current density in an electroplating apparatus

Patent metadata

Field	Value
Publication number	US-2016273124-A1
Application number	US-201514664652-A
Country	US
Kind code	A1
Filing date	Mar 20, 2015
Priority date	Nov 7, 2008
Publication date	Sep 22, 2016
Grant date	—

Abstract

Various embodiments herein relate to methods and apparatus for electroplating metal onto substrates. In various cases, a reference electrode may be modified to promote improved electroplating results. The modifications may relate to one or more of the reference electrode's shape, position, relative conductivity compared to the electrolyte, or other design feature. In some particular examples the reference electrode may be dynamically changeable, for example having a changeable shape and/or position. In a particular example the reference electrode may be made of multiple segments. The techniques described herein may be combined as desired for individual applications.

First claim

What is claimed is:

1 . An apparatus for electroplating metal onto a substrate, the apparatus comprising:
a chamber for holding electrolyte; a substrate holder for holding the substrate in the chamber; and a reference electrode, wherein the reference electrode is (a) shaped like a ring, (b) shaped like an arc, (c) shaped to include multiple independent segments, and/or (d) designed to include a dynamically changeable shape.

2 . The apparatus of claim 1 , wherein the reference electrode is ring-shaped.

3 . The apparatus of claim 1 , wherein the reference electrode is arc-shaped, the arc of the reference electrode spanning an angular extent between about 75-180°.

4 . The apparatus of claim 3 , wherein the arc spans an angular extent between about 105-150°.

5 . The apparatus of claim 3 , wherein the reference electrode is positioned such that a center portion of the reference electrode is positioned proximate a substrate entry position.

6 . The apparatus of claim 3 , wherein the reference electrode is positioned such that a center portion of the reference electrode is angularly offset from a substrate entry position, the angular offset being between about 30-90°.

7 . The apparatus of claim 1 , wherein the reference electrode is a multi-segment electrode comprising at least two segments that can be independently activated and/or deactivated.

8 . The apparatus of claim 7 , further comprising a controller having instructions to (i) activate multiple segments of the multi-segment electrode before immersing the substrate in electrolyte, and (ii) independently de-activate one or more of the segments of the multi-segment electrode as the substrate is immersed in electrolyte.

9 . The apparatus of claim 7 , wherein the multi-segment electrode comprises between about 4-6 segments, and wherein space between adjacent segments is between about 2.5-12.5 cm.

10 . The apparatus of claim 3 , wherein the reference electrode is designed to have a shape that is dynamically changeable to include at least a first shape and a second shape, the first and second shapes each being arc shapes, and the first and second shapes extending to different angular extents.

11 . The apparatus of claim 10 , further comprising a controller having instructions to change the shape of the reference electrode from the first shape to the second shape as the substrate is immersed in electrolyte.

12 . The apparatus of claim 11 , wherein the first shape extends to a greater angular extent than the second shape.

13 . A method of electroplating metal onto a semiconductor substrate, the method comprising:
immersing the substrate in electrolyte in an electroplating chamber; monitoring a potential difference between the substrate and a reference electrode, wherein the reference electrode is between about 10×-225× as conductive as the electrolyte; and electroplating metal onto the substrate.

14 . The method of claim 13 , wherein the reference electrode is ring-shaped and wherein the reference electrode is between about 10×-50× as conductive as the electrolyte.

15 . The method of claim 13 , wherein the reference electrode is arc-shaped, the arc of the reference electrode spanning an angular extent between about 75-150°, wherein the reference electrode is between about 100×-200× as conductive as the electrolyte.

16 . The method of claim 15 , wherein the arc of the reference electrode spans an angular extent between about 105-150°, wherein the reference electrode is between about 120×-200× as conductive as the electrolyte.

17 . The method of claim 13 , wherein the reference electrode is arc-shaped, the arc of the reference electrode spanning an angular extent between about 150-240°, wherein the reference electrode is between about 70×-100× as conductive as the electrolyte.

18 . An apparatus for electroplating metal onto a substrate, the apparatus comprising:
a chamber for holding electrolyte; a substrate holder for holding the substrate in the chamber; a reference electrode; and a controller having instructions for:
immersing the substrate in the electrolyte at an angle such that a leading edge of the substrate contacts the electrolyte before a trailing edge of the substrate, the leading edge of the substrate first contacting the electrolyte at a substrate entry position,
controlling a potential difference between the substrate and the reference electrode during immersion, and
electroplating metal onto the substrate;
wherein the reference electrode is positioned radially outside of the periphery of the substrate at a location that is angularly offset from the substrate entry position, the angular offset being between about 5-60°.

19 . The apparatus of claim 18 , wherein the reference electrode is a point reference electrode and the angular offset is between about 20-40°.

20 . The apparatus of claim 19 , wherein the angular offset is between about 25-35°.

Assignees

• Lam Res Corp

Inventors

• He Zhian
• Ramesh Ashwin
• Ghongadi Shantinath

Classifications

• H10W20/057

  by selectively depositing, e.g. by using selective CVD or plating · CPC title

• C25D17/007

  Current directing devices · CPC title

• C25D17/001 Primary

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

• C25D17/02

  Tanks; Installations therefor · CPC title

• C25D17/12 Primary

  Shape or form (C25D17/14 takes precedence) · CPC title