Methods and apparatuses for electroplating and seed layer detection

Patent metadata

Field	Value
Publication number	US-10407794-B2
Application number	US-201816228527-A
Country	US
Kind code	B2
Filing date	Dec 20, 2018
Priority date	Jan 21, 2014
Publication date	Sep 10, 2019
Grant date	Sep 10, 2019

Abstract

Disclosed herein are methods for electroplating which employ seed layer detection. Such methods may operate by selecting a wafer, illuminating one or more points within an interior region of the wafer surface, measuring a first set of one or more in-process color signals from the one or more points within the interior region, illuminating one or more points within an edge region of the wafer surface, measuring a second set of one or more in-process color signals from the one or more points within the edge region, each color signal having one or more color components, calculating a metric indicative of a difference between the color signals in the first and second sets of in-process color signals, determining whether an acceptable seed layer is present on the wafer based on whether the metric is within a predetermined range, and repeating the foregoing for one or more additional wafers.

First claim

We claim:

1. A method of determining whether a semiconductor wafer is acceptable for electroplating, the method comprising:
(a) selecting a wafer from the set for processing, wherein the wafer has a surface;
(b) after (a), illuminating one or more points within an interior region of the surface of the selected wafer and measuring a first set of one or more in-process color signals from the one or more points within the interior region of the surface of the selected wafer, each color signal having one or more color components;
(c) after (a), illuminating one or more points within an edge region of the surface of the selected wafer and measuring a second set of one or more in-process color signals from the one or more points within the edge region of the surface of the selected wafer, each color signal having one or more color components;
(d) calculating a metric indicative of a difference between the color signals in the first and second sets of in-process color signals;
(e) determining whether a seed layer acceptable for electroplating is present on the selected wafer surface based on whether the metric is within a predetermined range; and
(f) repeating (a) through (e) for one or more additional wafers from the set of wafers.

2. The method of claim 1 , wherein locations of the points on the surfaces of the wafers at which the first and second sets of color signals are measured are a fixed set of repeated azimuthal and radial positions relative to the wafer edge and alignment notch of each wafer.

3. The method of claim 1 , wherein:
the metric is indicative of a magnitude of a vector difference between:
a vector average of the first set of one or more in-process color signals; and
a vector average of the second set of one or more in-process color signals.

4. The method of claim 1 , wherein:
(b) further comprises
detecting a light reflected from the interior region with a color sensor; and

(c) further comprises
detecting a light reflected from the edge region with a color sensor.

5. The method of claim 1 , wherein the one or more color components of the color signals of the first and second sets comprise a first color component whose value is indicative of the relative proportion of green versus red in the color signals.

6. The method of claim 1 , wherein the one or more color components of the color signals of the first and second sets comprise a first color component whose value is indicative of the relative proportion of blue versus yellow in the color signals.

7. The method of claim 1 , wherein:
the illuminating in (b) further comprises illuminating the one or more points within the interior region of the surface of the selected wafer with substantially white light to reflect light from the interior region, and
the illuminating in (c) further comprises illuminating the one or more points within the edge region of the surface of the selected wafer with substantially white light to reflect light from the edge region.

8. The method of claim 1 , wherein locations of the points on the surfaces of the wafers at which the first and second sets of color signals are measured are chosen randomly.

9. The method of claim 1 , further comprising: (g) processing, before (a), each wafer by a physical vapor deposition (PVD) tool for depositing a seed layer.

10. The method of claim 1 , wherein the acceptable seed layer is a copper seed layer.

11. The method of claim 10 , wherein the acceptable seed layer is a copper seed layer having a thickness of less than about 200 angstroms.

12. The method of claim 11 , wherein the acceptable seed layer is a copper seed layer having a thickness of between about 50 and 150 angstroms.

13. The method of claim 1 , wherein:
the first set of one or more in-process color signals in (b) includes a first color signal and a second color signal,
the second set of one or more in-process color signals in (c) includes a third color signal and a fourth color signal,
(d) further comprises calculating a first metric indicative of a difference between the first color signal and the third color signal, and calculating a second metric indicative of a difference between the second color signal and the fourth color signal, and
(e) further comprises determining whether the acceptable seed layer is present on the wafer surface based on whether the first metric is within a predetermined range and whether the second metric is within a predetermine range.

14. The method of claim 1 , wherein the one or more color components of the first set of one or more in-process color signals and the one or more color components of the second set of one or more in-process color signals comprise a red color component.

15. The method of claim 1 , wherein the one or more color components of the first set of one or more in-process color signals and the one or more color components of the second set of one or more in-process color signals comprise a first color component and a second color component.

16. The method of claim 1 , wherein:
(a) further comprises selecting the wafer from one or more wafer storage devices for storing, loading, and unloading wafers, and
the method further comprises: (h) positioning, after (a) and before (b), the selected wafer for illumination by the illumination source.

Assignees

• Lam Res Corp

Inventors

• Dinneen Daniel Mark
• Mayer Steven T

Classifications

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• H10P72/04

  Apparatus for manufacture or treatment · CPC title

• C25D17/001

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

• C25D7/123 Primary

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

• C25D17/16 Primary

  Apparatus for electrolytic coating of small objects in bulk · CPC title