Electroplating and post-electrofill systems with integrated process edge imaging and metrology systems

Patent metadata

Field	Value
Publication number	US-9809898-B2
Application number	US-201313928141-A
Country	US
Kind code	B2
Filing date	Jun 26, 2013
Priority date	Jun 26, 2013
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

Disclosed herein are electroplating systems for forming a layer of metal on a wafer which include an electroplating module and a wafer edge imaging system. The electroplating module may include a cell for containing an anode and an electroplating solution during electroplating, and a wafer holder for holding the wafer in the electroplating solution and rotating the wafer during electroplating. The wafer edge imaging system may include a wafer holder for holding and rotating the wafer through different azimuthal orientations, a camera oriented for obtaining multiple azimuthally separated images of a process edge of the wafer while it is held and rotated (the process edge corresponding to the outer edge of the layer of metal formed on the wafer), and image analysis logic for determining an edge exclusion distance, wherein the edge exclusion distance is a distance between the wafer's edge and the process edge.

First claim

We claim:

1. An electroplating system for forming a layer of metal on a substantially circular wafer having a side edge, the system comprising:
an electroplating module comprising:
a cell for containing an anode and an electroplating solution during electroplating; and
a wafer holder for holding the wafer in the electroplating solution and rotating the wafer during electroplating;

an edge bevel removal module, the edge bevel removal module comprising:
a wafer holder for holding and rotating the wafer; and
a device for delivering etchant to an edge bevel region of the wafer while the wafer is held and rotated on the wafer holder of the edge bevel removal module to remove electroplated metal from the edge bevel region after electroplating in the electroplating module; and

a wafer edge imaging system comprising:
a wafer holder for holding and rotating the wafer through different azimuthal orientations;
a camera oriented for obtaining multiple azimuthally separated images of a process edge of the wafer while the wafer is held and rotated through different azimuthal orientations on the wafer holder of the imaging system, the process edge corresponding to the outer edge of the layer of metal formed on the wafer, wherein the camera is a color camera and each image generated by the color camera is represented as an array of pixels, each pixel comprising at least three color values; and
image analysis logic for determining an edge exclusion distance from the multiple azimuthally separated images, wherein the edge exclusion distance is a distance between the wafer's side edge and the process edge, wherein the image analysis logic further comprises EBR detection logic for determining from the multiple azimuthally separated images whether or not edge bevel removal (EBR) has been performed on the wafer by the edge bevel removal module; and

fault identification and reporting logic for reporting an error to an operator of the electroplating system when the image analysis logic determines that EBR has not been performed.

2. The electroplating system of claim 1 , further comprising fault identification and reporting logic for reporting an error to an operator of the electroplating system when the image analysis logic determines that an edge exclusion distance is outside a predetermined range.

3. The electroplating system of claim 1 , wherein the image analysis logic determines multiple azimuthally separated edge exclusion distances from the multiple azimuthally separated images, wherein each edge exclusion distance is a distance between the wafer's side edge and the process edge at a particular azimuthal angle.

4. The electroplating system of claim 3 , wherein the image analysis logic further comprises concentricity analysis logic for determining that the wafer's side edge and imaged process edge are concentric when a metric indicative of a statistical variation in the multiple edge exclusion distances over different azimuthal angles is within a predetermined threshold value and non-concentric when the metric exceeds the threshold value.

5. The electroplating system of claim 4 , wherein the metric is the standard deviation of the edge exclusion distances over different azimuthal angles.

6. The electroplating system of claim 4 , further comprising wafer centering adjustment logic for adjusting centering of one or more subsequently processed wafers within the electroplating module when a determination is made that a currently imaged wafer's side edge and process edge are non-concentric.

7. The electroplating system of claim 4 , further comprising fault identification and reporting logic for reporting an error to an operator of the electroplating system when the concentricity analysis logic determines that an imaged wafer's side edge and process edge are non-concentric.

8. The electroplating system of claim 1 , wherein the image analysis logic further comprises sharpness analysis logic for analyzing images of the process edge and determining a sharpness of the process edge in the images.

9. The electroplating system of claim 1 :
wherein the wafer edge imaging system is configured to operate in multiple imaging modes and to obtain multiple azimuthally separated images of the process edge using the multiple imaging modes; and
wherein the wafer edge imaging system further comprises an image optimization subsystem for determining an imaging mode which generates images of the process edge that are sharpest, and selecting the images generated using the imaging mode which generates images of the process edge that are sharpest for use by the image analysis logic to determine an edge exclusion distance.

10. The electroplating system of claim 9 , wherein the wafer edge imaging system includes an illumination subsystem having a light source with adjustable illumination intensity, and wherein the multiple imaging modes comprise distinct combinations of settings for illumination intensity and exposure times.

11. The electroplating system of claim 1 , wherein the wafer edge imaging system further comprises an illumination subsystem having a diffuse light source for illuminating the wafer's side edge with light comprising either diffuse low angle light or diffuse on-axis light relative to a horizontal plane of a surface of the wafer.

12. The electroplating system of claim 1 , wherein the image analysis logic further comprises logic for determining a taper width of the process edge from the multiple azimuthally separated images.

13. The electroplating system of claim 1 , the camera is a color camera.

14. The electroplating system of claim 13 , wherein each of the images generated by the color camera is represented as an array of pixels, each pixel comprising at least three color values.

15. The electroplating system of claim 14 , wherein in the multiple azimuthally separated images, the process edge is identified as a narrow region having the greatest color contrast between adjacent pixels.

16. The electroplating system of claim 15 :
wherein the image analysis logic further comprises logic for determining a taper width of the process edge from the multiple azimuthally separated images;
wherein the wafer edge imaging system is configured to operate in multiple imaging modes and to obtain multiple azimuthally separated images of the process edge using the multiple imaging modes; and
wherein the wafer edge imaging system further comprises an image optimization subsystem for determining an imaging mode which generates images of the process edge having the highest color contrast between pixels on either side of the process edge, and selecting the images generated using the imaging mode which generates images of the process edge having the highest color contrast between pixels on either side of the process edge for use by the image analysis logic to determine the taper width.

17. The electroplating system of claim 16 :
wherein the wafer edge imaging system further comprises an illumination subsystem having a diffuse light source for illuminating the wafer's side edge with diffuse low angle light relative to a horizontal plane of a surface of the wafer; and
wherein the wafer edge imaging system's multiple imaging modes comprises distinct combinations of settings for illumination intensity, and exposure times.

18. The electroplating system of claim 17 , wherein the multiple imaging modes further comprise distinct settings for color hue, saturation, and intensity.

19. The electroplating system of claim 1 , wherein the wafer holder of the wafer edge imaging system is

Assignees

• Novellus Systems Inc
• Lam Res Corp

Inventors

• Dinneen Daniel Mark
• Duncan James E

Classifications

• H10P70/56

  Cleaning of wafer backside · CPC title

• H10P70/54

  Cleaning of wafer edges · CPC title

• H10P72/0604 Primary

  Process monitoring, e.g. flow or thickness monitoring · CPC title

• H10W20/056

  by filling conductive material into holes, grooves or trenches · CPC title

• C25D21/10

  Agitating of electrolytes; Moving of racks · CPC title