USE OF DOPANTS WITH DIFFERENT DIFFUSIVITIES FOR SOLAR CELL MANUFACTURE

• US 20090227097A1
• Filed: 03/04/2009
• Published: 09/10/2009
• Est. Priority Date: 03/05/2008
• Status: Active Grant

• Current Assignee: Varian Semiconductor Equipment Associates Incorporated (Applied Materials Incorporated)
• Original Assignee: Varian Semiconductor Equipment Associates Incorporated (Applied Materials Incorporated)
• Inventors: Hatem, Christopher, Gupta, Atul, Ramappa, Deepak, Bateman, Nicholas
• Granted Patent: US 8,461,032 B2
• Time in Patent Office: Days
• US Class Current: 438/530
• CPC Class Codes: H01L 21/26513 of electrically active species
• CPC Class Codes: H01L 21/2658 of a molecular ion, e.g. decaborane
• CPC Class Codes: H01L 31/022441 Electrode arrangements specially adapted for back-contact solar cells
• CPC Class Codes: H01L 31/0236 Special surface textures
• CPC Class Codes: H01L 31/03529 Shape of the potential jump barrier or surface barrier
• CPC Class Codes: H01L 31/0682 back-junction, i.e. rearside emitter, solar cells, e.g. interdigitated base-emitter regions back-junction cells
• CPC Class Codes: H01L 31/1864 Annealing
• CPC Class Codes: H01L 33/025 Physical imperfections, e.g. particular concentration or distribution of impurities
• 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 tailoring the dopant profile of a substrate by utilizing two different dopants, each having a different diffusivity is disclosed. The substrate may be, for example, a solar cell. By introducing two different dopants, such as by ion implantation, furnace diffusion, or paste, it is possible to create the desired dopant profile. In addition, the dopants may be introduced simultaneously, partially simultaneously, or sequentially. Dopant pairs preferably consist of one lighter species and one heavier species, where the lighter species has a greater diffusivity. For example, dopant pairs such as boron and gallium, boron and indium, phosphorus and arsenic, and phosphorus and antimony, can be utilized.

Claims

1. A method of creating a desired dopant profile in a solar cell, comprising:

introducing a first dopant;

introducing a second dopant, having a lower diffusivity than said first dopant; and

performing a thermal cycle so as to allow said dopants to diffuse into said solar cell.

2. The method of claim 1, wherein said first and second dopant are selected from the group consisting of nitrogen, phosphorus, arsenic, antimony, bismuth, boron, aluminum, gallium, and indium.

3. The method of claim 1, wherein said first and second dopants are introduced at least partially simultaneously.

4. The method of claim 1, wherein said first and second dopants are introduced using ion implantation.

5. The method of claim 4, wherein a flood implant is performed.

6. The method of claim 1, wherein one of said dopants is introduced using ion implantation and the second of said dopants is introduced during said thermal cycle.

7. The method of claim 6, wherein said second dopant is introduced using furnace diffusion.

8. The method of claim 1, wherein said first and second dopants are introduced using ion implantation of a molecular ion comprising both dopants.

9. The method of claim 8, wherein said molecular ion is selected from the group consisting of arsenic monophosphide, diarsenic diphosphide, triarsenic phosphide, and arsenic triphosphide.

10. The method of claim 1, wherein said first and second dopants are introduced via paste applied to the surface of said solar cell.

11. A method of creating a desired dopant profile in a substrate comprising:

introducing a first dopant;

introducing a second dopant, having a lower diffusivity than said first dopant, while said first dopant is being introduced; and

performing a thermal cycle so as to allow said first and second dopants to diffuse into said substrate.

12. The method of claim 11, wherein said first and second dopant are selected from the group consisting of nitrogen, phosphorus, arsenic, antimony, bismuth, boron, aluminum, gallium, and indium.

13. The method of claim 11, wherein said first and second dopants are introduced using ion implantation.

14. The method of claim 13, wherein a flood implant is performed.

15. The method of claim 11, wherein said dopants are introduced using furnace diffusion.

16. The method of claim 11, wherein said first and second dopants are introduced using ion implantation of a molecular ion comprising both dopants.

17. The method of claim 16, wherein said molecular ion is selected from the group consisting of arsenic monophosphide, diarsenic diphosphide, triarsenic phosphide, and arsenic triphosphide.

18. The method of claim 11, wherein said first and second dopants are introduced via a paste applied to the surface of said substrate.

19. A method of creating a desired dopant profile in a substrate comprising:

introducing a first dopant;

performing a thermal cycle so as to allow said first dopant to diffuse into said substrate;

and introducing a second dopant, having a lower diffusivity than said first dopant, while said thermal cycle is being performed.

20. The method of claim 19, wherein said first dopant is introduced using ion implantation.