METHOD FOR FORMING DIFFUSION REGIONS IN A SILICON SUBSTRATE

• US 20130081687A1
• Filed: 09/30/2011
• Published: 04/04/2013
• Est. Priority Date: 09/30/2011
• Status: Active Grant

• Current Assignee: Sunpower Corporation (Totalenergies Se)
• Original Assignee: Sunpower Corporation (Totalenergies Se)
• Inventors: Kraft, Steven M., Loscutoff, Paul, Molesa, Steven Edward, Wu, Kahn C.
• Granted Patent: US 8,586,397 B2
• Time in Patent Office: Days
• US Class Current: 136/256
• CPC Class Codes: H01L 31/028 including, apart from doping material or other impurities, only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/182 Special manufacturing methods for polycrystalline Si, e.g. Si ribbon, poly Si ingots, thin films of polycrystalline Si
• CPC Class Codes: Y02E 10/546 Polycrystalline silicon PV cells
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A method of manufacturing solar cells is disclosed. The method comprises depositing an etch-resistant dopant material on a silicon substrate, the etch-resistant dopant material comprising a dopant source, forming a cross-linked matrix in the etch-resistant dopant material using a non-thermal cure of the etch-resistant dopant material, and heating the silicon substrate and the etch-resistant dopant material to a temperature sufficient to cause the dopant source to diffuse into the silicon substrate.

Claims

1. ) A method of manufacturing solar cells, the method comprising:

depositing an etch-resistant dopant material on a silicon substrate, the etch-resistant dopant material comprising a dopant source;

forming a cross-linked matrix in the etch-resistant dopant material using a non-thermal cure of the etch-resistant dopant material; and

heating the silicon substrate and the etch-resistant dopant material to a temperature sufficient to cause the dopant source to diffuse into the silicon substrate.

2. ) The method of claim 1, wherein forming a cross-linked matrix in the etch-resistant dopant material using a non-thermal cure of the etch-resistant dopant material comprises causing a phase change from liquid to solid of the etch-resistant dopant material on the silicon substrate.

3. ) method of claim 1, wherein forming a cross-linked matrix in the etch-resistant dopant material using a non-thermal cure of the etch-resistant dopant material comprises exposing the etch-resistant dopant material to non-infrared electromagnetic radiation.

4. ) method of claim 3, wherein exposing the etch-resistant dopant material to non-infrared electromagnetic radiation comprises exposing the etch-resistant dopant material to ultraviolet light.

5. ) method of claim 3, wherein exposing the etch-resistant dopant material to non-infrared electromagnetic radiation comprises exposing the etch-resistant dopant material with light from the visible spectrum or electromagnetic radiation having a wavelength of 380 to 760 nanometers.

6. ) The method of claim 1, wherein forming a cross-linked matrix in the etch-resistant dopant material using a non-thermal cure of the etch-resistant dopant material comprises transmitting acoustic waves toward the etch-resistant dopant material.

7. ) The method of claim 1, wherein depositing the etch-resistant dopant material comprises dispensing the etch-resistant dopant in liquid form on the silicon substrate.

8. ) The method of claim 7, wherein dispensing the etch-resistant dopant material comprises screen printing the etch-resistant dopant material onto a silicon substrate.

9. ) The method of claim 7, wherein dispensing the etch-resistant dopant material comprises ink-jet printing the etch-resistant dopant material onto a silicon substrate.

10. ) The method of claim 7, wherein dispensing the etch-resistant dopant material comprises spin coating the etch-resistant dopant material onto a silicon substrate.

11. ) The method of claim 1, wherein dispensing the etch-resistant dopant material comprising a dopant source onto the silicon substrate comprises dispensing a dopant material comprising a single-polarity dopant source onto the silicon substrate.

12. ) The method of claim 11, wherein dispensing a dopant material comprising a single-polarity dopant source onto the silicon substrate comprises dispensing a positive-type dopant onto the silicon substrate.

13. ) The method of claim 11, wherein dispensing a dopant material comprising a single-polarity dopant source onto the silicon substrate comprises dispensing a negative-type dopant onto the silicon substrate.

14. ) The method of claim 1, further comprising selectively etching the silicon substrate to remove the dopant source material without etching the silicon substrate.

15. ) The method of claim 1, further comprising the step of reducing the amount of solvent in the etch-resistant dopant material by heating the etch-resistant dopant material to at least 400°

Celsius after forming the cross-linked matrix in the etch-resistant dopant material.

16. ) A solar cell fabricated in accordance to the method of claim 1.

17. ) A method of manufacturing solar cells, the method comprising:

depositing a dopant material on a silicon substrate having a photovoltaic solar cell structure;

forming a cross-linked matrix in the dopant material using a non-thermal exposure of the dopant material to ultraviolet light through a photo-polymerization process; and

heating the silicon substrate of the dopant material to a temperature sufficient to cause the dopant source to diffuse into the silicon substrate.

18. ) The method of claim 17, wherein forming a cross-linked matrix in the dopant material using a non-thermal exposure of the dopant material to ultraviolet light comprises exposing the dopant material to electromagnetic radiation having a wavelength of 8 to 400 nanometers.

19. ) The method of claim 17, wherein forming a cross-linked matrix in the dopant material using a non-thermal exposure of the dopant material to ultraviolet light comprises exposing the dopant material to ultraviolet light forming a phase change from liquid to solid of the dopant material during the photo-polymerization process.

20. ) The method of claim 17, wherein forming a cross-linked matrix in the dopant material using a non-thermal exposure of the dopant material to ultraviolet light comprises exposing the dopant material to perform a curing step selected from the group comprising acrylate polymerization, cationic polymerization, thiolene chemical application and hydrosilane addition.

21. ) The method of claim 17, wherein depositing the dopant material comprises depositing a chemical group comprising a chemical structure selected from the group comprising silanes, cyclosilanes, and siloxanes.

22. ) The method of claim 17, further comprising the step of etching the silicon substrate using the dopant material as an etch-mask after forming the cross-linked matrix in the dopant material.

23. ) method of claim 22, wherein etching the silicon substrate comprises etching at least part of the photovoltaic solar cell structure of the silicon substrate.

24. ) A solar cell fabricated in accordance to the method of claim 17.

25. ) A method of manufacturing solar cells, the method comprising:

forming a thin dielectric layer on a surface of a silicon substrate;

forming a polysilicon layer over the thin dielectric layer;

depositing an etch-resistant dopant material comprising a dopant source material on the polysilicon layer;

forming a cross-linked matrix in the etch-resistant dopant material using a non-thermal cure of the etch-resistant dopant material; and

heating the etch-resistant dopant material to a temperature wherein the dopant source material diffuses into the polysilicon layer.

26. ) The method of claim 25, further comprising the step of etching the polysilicon layer using the etch-resistant dopant material as an etch-mask.

27. ) The method of claim 25, wherein depositing the etch-resistant dopant material comprises dispensing the etch-resistant dopant material in a plurality of interdigitated contact fingers on the silicon substrate.

28. ) A solar cell fabricated in accordance to the method of claim 25.