Laser beam shaping for foil-based metallization of solar cells

Patent metadata

Field	Value
Publication number	US-9620661-B2
Application number	US-201414578334-A
Country	US
Kind code	B2
Filing date	Dec 19, 2014
Priority date	Dec 19, 2014
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

Approaches for foil-based metallization of solar cells and the resulting solar cells are described. For example, a method of fabricating a solar cell involves locating a metal foil above a plurality of alternating N-type and P-type semiconductor regions disposed in or above a substrate. The method also involves laser welding the metal foil to the alternating N-type and P-type semiconductor regions. The method also involves patterning the metal foil by laser ablating through at least a portion of the metal foil at regions in alignment with locations between the alternating N-type and P-type semiconductor regions. The laser welding and the patterning are performed at the same time.

First claim

What is claimed is:

1. A method of fabricating a solar cell, the method comprising:
locating a metal foil above a plurality of alternating N-type and P-type semiconductor regions disposed in or above a substrate;
laser welding the metal foil to the alternating N-type and P-type semiconductor regions; and
patterning the metal foil by laser ablating through at least a portion of the metal foil at regions in vertical alignment with locations on the border between adjacent ones of the alternating N-type and P-type semiconductor regions, the laser welding and the patterning performed at the same time with the same laser beam.

2. The method of claim 1 , wherein laser ablating through at least a portion of the metal foil comprises laser ablating through an entire thickness of the metal foil.

3. The method of claim 1 , wherein laser ablating through at least a portion of the metal foil comprises laser ablating through only a portion of the metal foil, the portion having a thickness in the range of 80-99% of an entire thickness of the metal foil.

4. The method of claim 3 , further comprising:
subsequent to patterning the metal foil, etching the remaining metal foil to isolate regions of the remaining metal foil in alignment with the alternating N-type and P-type semiconductor regions.

5. The method of claim 3 , further comprising:
subsequent to patterning the metal foil, anodizing the remaining metal foil to isolate regions of the remaining metal foil in alignment with the alternating N-type and P-type semiconductor regions.

6. The method of claim 1 , further comprising:
prior to locating the metal foil, forming a plurality of metal seed material regions to provide a metal seed material region on each of the alternating N-type and P-type semiconductor regions, wherein laser welding the metal foil to the alternating N-type and P-type semiconductor regions comprises laser welding the metal foil to the plurality of metal seed material regions.

7. The method of claim 6 ,
wherein forming the plurality of metal seed material regions comprises forming aluminum regions each having a thickness in the range of 0.3 to 20 microns and comprising aluminum in an amount greater than 97 atomic and silicon in an amount in the range of 0-2 atomic %, wherein laser welding the metal foil comprises laser welding an aluminum foil having a thickness in the range of 5-100 microns.

8. The method of claim 1 , further comprising:
forming the plurality of alternating N-type and P-type semiconductor regions by forming alternating N-type and P-type regions in a polycrystalline silicon layer formed above the substrate, and forming a trench between each of the alternating N-type and P-type regions in the polycrystalline silicon layer, the trenches extending partially into the substrate.

9. A method of fabricating a solar cell, the method comprising:
locating a metal foil above a plurality of alternating N-type and P-type semiconductor regions disposed in or above a substrate;
impinging an incident laser beam on the metal foil, the incident laser beam comprising a beam shape having an inner region of lower intensity and an outer region of higher intensity, the inner region and the outer region relative to a central axis of the incident laser beam;
laser welding the metal foil to the alternating N-type and P-type semiconductor regions with the inner region of the incident laser beam; and
patterning the metal foil by laser ablating with the outer region of the incident laser beam through at least a portion of the metal foil at regions in vertical alignment with locations on the border between adjacent ones of the alternating N-type and P-type semiconductor regions.

10. The method of claim 9 , wherein impinging the incident laser beam on the metal foil comprises generating a laser beam having the beam shape from a laser cavity.

11. The method of claim 9 , wherein impinging the incident laser beam on the metal foil comprises shaping a laser beam to have the beam shape using optical diffraction.

12. The method of claim 9 , wherein laser ablating through at least a portion of the metal foil comprises laser ablating through an entire thickness of the metal foil.

13. The method of claim 9 , wherein laser ablating through at least a portion of the metal foil comprises laser ablating through only a portion of the metal foil, the portion having a thickness in the range of 80-99% of an entire thickness of the metal foil.

14. A method of fabricating a solar cell, the method comprising:
locating a metal foil above a plurality of alternating N-type and P-type semiconductor regions disposed in or above a substrate;
impinging an incident laser beam on the metal foil, the incident laser beam comprising a beam shape having an inner region of higher intensity and an outer region of lower intensity, the inner region and the outer region relative to a central axis of the incident laser beam;
laser welding the metal foil to the alternating N-type and P-type semiconductor regions with the outer region of the incident laser beam; and
patterning the metal foil by laser ablating with the inner region of the incident laser beam through at least a portion of the metal foil at regions in vertical alignment with locations on the border between adjacent ones of the alternating N-type and P-type semiconductor regions.

15. The method of claim 14 , wherein impinging the incident laser beam on the metal foil comprises generating a laser beam having the beam shape from a laser cavity.

16. The method of claim 14 , wherein impinging the incident laser beam on the metal foil comprises shaping a laser beam to have the beam shape using optical diffraction.

17. The method of claim 14 , wherein laser ablating through at least a portion of the metal foil comprises laser ablating through an entire thickness of the metal foil.

18. The method of claim 14 , wherein laser ablating through at least a portion of the metal foil comprises laser ablating through only a portion of the metal foil, the portion having a thickness in the range of 80-99% of an entire thickness of the metal foil.

Assignees

• Kim Taeseok
• Harley Gabriel
• Viatella John Wade
• Jaffrennou Perine
• Sunpower Corp
• Total Marketing Services

Inventors

• Kim Taeseok
• Harley Gabriel
• Viatella John Wade
• Jaffrennou Perine

Classifications

• H10W72/071

  Connecting or disconnecting · CPC title

• Y02E10/50

  Photovoltaic [PV] energy · CPC title

• B23K26/354

  by melting · CPC title

• B23K26/364

  for making a groove or trench, e.g. for scribing a break initiation groove · CPC title

• H01L31/022441

  Electricity · mapped topic