Wafer alignment with restricted visual access

Patent metadata

Field	Value
Publication number	US-9796045-B2
Application number	US-201314135147-A
Country	US
Kind code	B2
Filing date	Dec 19, 2013
Priority date	Dec 19, 2013
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

Wafer alignment with restricted visual access has been disclosed. In an example, a method of processing a substrate for fabricating a solar cell involves supporting the substrate over a stage. The method involves forming a substantially opaque layer over the substrate. The substantially opaque layer at least partially covers edges of the substrate. The method involves performing fit-up of the substantially opaque layer to the substrate. The method involves illuminating the covered edges of the substrate with light transmitted through the stage, and capturing a first image of the covered edges of the substrate based on the light transmitted through the stage. The method further includes determining a first position of the substrate relative to the stage based on the first image of the covered edges. The substrate may be further processed based on the determined first position of the substrate under the substantially opaque layer.

First claim

What is claimed is:

1. A method of processing a substrate for fabricating a solar cell, the method comprising:
supporting the substrate over a stage;
forming a substantially opaque layer over the substrate, the substantially opaque layer at least partially covering edges of the substrate, wherein forming the substantially opaque layer over the substrate comprises placing a metal sheet over the substrate;
performing fit-up of the substantially opaque layer to the substrate, wherein the substantially opaque layer extends beyond the edges of the substrate outside of a perimeter of the substrate following the fit-up, wherein performing fit-up comprises applying pressure to the metal sheet;
illuminating the at least partially covered edges of the substrate with light transmitted through the stage;
capturing a first image of the at least partially covered edges of the substrate based on the light transmitted through the stage;
determining a first position of the substrate relative to the stage based on the first image of the at least partially covered edges;
processing the substrate based on the determined first position of the substrate under the substantially opaque layer, wherein processing the substrate based on the determined first position comprises applying a laser to at least the metal sheet or a metal layer of the substrate;
capturing a second image of the at least partially covered edges of the substrate after said applying the laser; and
determining a second position of the substrate relative to the stage based on the second image of the at least partially covered edges.

2. The method of claim 1 , wherein
capturing the first image of the at least partially covered edges of the substrate comprises capturing the first image through one or more substantially transparent windows in the stage.

3. The method of claim 1 , wherein
capturing the first image of the at least partially covered edges of the substrate comprises capturing the first image through the stage.

4. The method of claim 1 , wherein capturing the first image of the at least partially covered edges comprises capturing the first image with an image sensor located below the stage.

5. The method of claim 1 , wherein illuminating the at least partially covered edges of the substrate with light transmitted through the stage comprises illuminating with dark field illumination.

6. The method of claim 1 , wherein illuminating the at least partially covered edges of the substrate comprises illuminating the at least partially covered edges with one or more light sources located in the stage.

7. The method of claim 1 , wherein illuminating the at least partially covered edges of the substrate comprises illuminating the at least partially covered edges with one or more light sources located below the stage.

8. The method of claim 1 , wherein capturing the first image comprises capturing an image of each of the at least partially covered edges of the substrate.

9. The method of claim 1 , wherein capturing the first image comprises capturing an image of each of a plurality of corners of the substrate.

10. A method of processing a substrate for fabricating a solar cell, the method comprising:
supporting the substrate over a stage;
forming a substantially opaque layer over the substrate, the substantially opaque layer at least partially covering edges of the substrate, wherein forming the substantially opaque layer over the substrate comprises placing a metal sheet over the substrate;
performing fit-up of the substantially opaque layer to the substrate, wherein the substantially opaque layer extends beyond the edges of the substrate outside of a perimeter of the substrate following the fit-up, wherein performing fit-up comprises applying pressure to the metal sheet;
illuminating the at least partially covered edges of the substrate with light transmitted through the stage;
capturing a first image of the at least partially covered edges of the substrate based on the light transmitted through the stage;
determining a first position of the substrate relative to the stage based on the first image of the at least partially covered edges;
processing the substrate based on the determined first position of the substrate under the substantially opaque layer, wherein processing the substrate based on the determined first position comprises applying a laser to at least the metal sheet or a metal layer of the substrate;
patterning the metal sheet;
capturing a second image of the at least partially covered edges of the substrate after patterning the metal sheet;
determining a second position of the substrate relative to the stage based on the second captured image of the at least partially covered edges; and
trimming the patterned metal sheet.

11. The method of claim 10 , wherein
capturing the first image of the at least partially covered edges of the substrate comprises capturing the first image through one or more substantially transparent windows in the stage.

12. The method of claim 10 , wherein
capturing the first image of the at least partially covered edges of the substrate comprises capturing the first image through the stage.

13. The method of claim 10 , wherein capturing the first image of the at least partially covered edges comprises capturing the first image with an image sensor located below the stage.

14. The method of claim 10 , wherein illuminating the at least partially covered edges of the substrate with light transmitted through the stage comprises illuminating with dark field illumination.

15. The method of claim 10 , wherein illuminating the at least partially covered edges of the substrate comprises illuminating the at least partially covered edges with one or more light sources located in the stage.

16. The method of claim 10 , wherein illuminating the at least partially covered edges of the substrate comprises illuminating the at least partially covered edges with one or more light sources located below the stage.

17. The method of claim 10 , wherein capturing the first image comprises capturing an image of each of the at least partially covered edges of the substrate.

18. The method of claim 10 , wherein capturing the first image comprises capturing an image of each of a plurality of corners of the substrate.

19. A method of processing a substrate for fabricating a solar cell, the method comprising:
supporting the substrate over a stage;
forming a substantially opaque layer over the substrate, the substantially opaque layer at least partially covering edges of the substrate, wherein forming the substantially opaque layer over the substrate comprises placing a metal sheet over the substrate;
performing fit-up of the substantially opaque layer to the substrate, wherein the substantially opaque layer extends beyond the edges of the substrate outside of a perimeter of the substrate following the fit-up;
illuminating the at least partially covered edges of the substrate with light transmitted through the stage;
capturing a first image of the at least partially covered edges of the substrate based on the light transmitted through the stage;
determining a first position of the substrate relative to the stage based on the first image of the at least partially covered edges;
processing the substrate based on the determined first position of the substrate under the substantially opaque layer, wherein processing the substrate based on the determined first position comprises applying a laser to at least the metal sheet or a metal layer of the substrat

Assignees

• Pass Thomas
• Sunpower Corp

Inventors

• Pass Thomas

Classifications

• H10P72/0606

  Position monitoring, e.g. misposition detection or presence detection · CPC title

• H10P72/53 Primary

  using optical controlling means · CPC title

• G03F9/7088

  Alignment mark detection, e.g. TTR, TTL, off-axis detection, array detector, video detection · CPC title

• B23K26/032 Primary

  using optical means · CPC title

• G03F9/7084

  Position of mark on substrate, i.e. position in (x, y, z) of mark, e.g. buried or resist covered mark, mark on rearside, at the substrate edge, in the circuit area, latent image mark, marks in plural levels · CPC title