Method for forming diffusion regions in a silicon substrate

Patent metadata

Field	Value
Publication number	US-9018033-B2
Application number	US-201314061422-A
Country	US
Kind code	B2
Filing date	Oct 23, 2013
Priority date	Sep 30, 2011
Publication date	Apr 28, 2015
Grant date	Apr 28, 2015

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.

First claim

What is claimed is:

1. 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, in liquid phase, an etch-resistant dopant material comprising a dopant source material and a solvent 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, the cross-linked matrix having a structure, and the non-thermal cure causing a phase change of the etch-resistant dopant material from liquid to solid; subsequently,
removing the solvent from the etch-resistant dopant material without altering the structure of the cross-linked matrix; and
heating the etch-resistant dopant material to a temperature wherein the dopant source material diffuses into the polysilicon layer.

2. The method of claim 1 , further comprising the step of etching the polysilicon layer using the etch-resistant dopant material as an etchmask.

3. The method of claim 1 , 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.

4. A method of manufacturing solar cells, the method comprising:
depositing, in a liquid phase, an etch-resistant dopant material on a polysilicon layer disposed on a thin dielectric layer disposed on a silicon substrate, the etch-resistant dopant material comprising a dopant source and a solvent;
forming a cross-linked matrix in the etch-resistant dopant material using a non-thermal cure of the etch-resistant dopant material, the cross-linked matrix having a structure, and the non-thermal cure causing a phase change of the etch-resistant dopant material from liquid to solid; subsequently,
removing the solvent from the etch-resistant dopant material without altering the structure of the cross-linked matrix; and
heating the polysilicon layer and the etch-resistant dopant material having the cross-linked matrix to a temperature sufficient to cause the dopant source to diffuse into the polysilicon layer.

5. The method of claim 4 , wherein forming the cross-linked matrix in the etch-resistant dopant material using the non-thermal cure of the etch-resistant dopant material comprises exposing the etch-resistant dopant material to non-infrared electromagnetic radiation.

6. The method of claim 5 , wherein exposing the etch-resistant dopant material to the non-infrared electromagnetic radiation comprises exposing the etch-resistant dopant material to ultraviolet light.

7. The method of claim 5 , wherein exposing the etch-resistant dopant material to the 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.

8. The method of claim 4 , wherein forming the cross-linked matrix in the etch-resistant dopant material using the non-thermal cure of the etch-resistant dopant material comprises transmitting acoustic waves toward the etch-resistant dopant material.

9. The method of claim 4 , wherein depositing the etch-resistant dopant material comprises dispensing the etch-resistant dopant on the polysilicon layer.

10. The method of claim 9 , wherein dispensing the etch-resistant dopant material comprises screen printing the etch-resistant dopant material onto the polysilicon layer.

11. The method of claim 9 , wherein dispensing the etch-resistant dopant material comprises ink-jet printing the etch-resistant dopant material onto the polysilicon layer.

12. The method of claim 9 , wherein dispensing the etch-resistant dopant material comprises spin coating the etch-resistant dopant material onto the polysilicon layer.

13. The method of claim 9 , wherein dispensing the etch-resistant dopant material comprising the dopant source onto the polysilicon layer comprises dispensing a dopant material comprising a single-polarity dopant source onto the polysilicon layer.

14. The method of claim 13 , wherein dispensing the dopant material comprising the single-polarity dopant source onto the polysilicon layer comprises dispensing a positive-type dopant onto the polysilicon layer.

15. The method of claim 13 , wherein dispensing the dopant material comprising the single-polarity dopant source onto the polysilicon layer comprises dispensing a negative-type dopant onto the polysilicon layer.

16. The method of claim 4 , wherein removing the solvent from the etch-resistant dopant material comprises heating the etch-resistant dopant material to at least 400° Celsius.

17. A method of manufacturing solar cells, the method comprising:
depositing, in a liquid phase, a dopant material on a polysilicon layer disposed on a thin dielectric layer disposed on a silicon substrate having a photovoltaic solar cell structure, the dopant material comprising a dopant and a solvent;
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, the cross-linked matrix having a structure, and the photo-polymerization process causing a phase change of the dopant material from liquid to solid; subsequently,
removing the solvent from the dopant material without altering the structure of the cross-linked matrix; and
heating the polysilicon layer and the dopant material having the cross-linked matrix to a temperature sufficient to cause the dopant to diffuse into the polysilicon layer.

18. The method of claim 17 , wherein forming the cross-linked matrix in the dopant material using the non-thermal exposure of the dopant material to the 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 depositing the dopant material comprises depositing a chemical group comprising a chemical structure selected from the group comprising silanes, cyclosilanes, and siloxanes.

Assignees

• Wu Kahn C
• Kraft Steven M
• Loscutoff Paul
• Molesa Steven Edward
• Sunpower Corp

Inventors

• Wu Kahn C
• Kraft Steven M
• Loscutoff Paul
• Molesa Steven Edward

Classifications

• H10F77/122

  comprising only Group IV materials · CPC title

• H10F71/1221 Primary

  comprising polycrystalline silicon · CPC title

• H01L31/028

  Electricity · mapped topic

• Y02E10/546

  Polycrystalline silicon PV cells · CPC title

• H01L31/182 Primary

  Electricity · mapped topic