Method of forming contacts for a back-contact solar cell

1. A method of forming contacts for a back-contact solar cell, the method comprising:

forming a thin dielectric layer on a substrate;

forming a polysilicon layer on the thin dielectric layer;

forming and patterning a solid-state p-type dopant source on the polysilicon layer, the patterning exposing regions of the polysilicon layer between a plurality of regions of the solid-state p-type dopant source;

forming an n-type dopant source layer over the exposed regions of the polysilicon layer and the plurality of regions of the solid-state p-type dopant source, the forming comprising at least partially driving dopants from the n-type dopant source layer into the exposed regions of the polysilicon layer to form a plurality of n-type dopant-containing polysilicon regions between the plurality of regions of the solid-state p-type dopant source; and, subsequently,

heating the substrate to provide a plurality of n-type doped polysilicon regions among a plurality of p-type doped polysilicon regions and, prior to the heating, removing the plurality of regions of the solid-state p-type dopant source.

2. The method of claim 1 , further comprising:

subsequent to forming an n-type dopant source layer and prior to heating the substrate, forming trenches between the plurality of n-type dopant-containing polysilicon regions and the plurality of regions of the solid-state p-type dopant source, the trenches formed in the polysilicon layer, in the thin dielectric layer, and partially in the substrate.

3. The method of claim 2 , further comprising:

subsequent to forming the trenches and prior to heating the substrate, texturizing portions of the substrate exposed by the trenches.

4. The method of claim 3 , wherein forming the trenches and the texturizing is performed without a cure operation between the forming the trenches and the texturizing.

5. The method of claim 1 , wherein forming the n-type dopant source layer further comprises at least partially driving dopants from the plurality of regions of the solid-state p-type dopant source into the polysilicon layer.

6. The method of claim 5 , wherein heating the substrate comprises activating the dopants in the plurality of n-type dopant-containing polysilicon regions, furthering the driving of dopants originating from the plurality of regions of the solid-state p-type dopant source into the polysilicon layer, and activating the dopants of the plurality of regions of the solid-state p-type dopant source in the polysilicon layer.

7. The method of claim 1 , wherein forming and patterning the solid-state p-type dopant source comprises forming and patterning a layer of boron silicate glass (BSG).

8. The method of claim 1 , wherein forming the n-type dopant source layer comprises forming a layer of P 2 O 5 .

9. The method of claim 1 , further comprising:

forming, by laser ablation, a plurality of contact openings to the plurality of n-type doped polysilicon regions and the plurality of p-type doped polysilicon regions.

10. A solar cell fabricated according to the method of claim 1 .

11. A method of forming contacts for a back-contact solar cell, the method comprising:

forming a thin dielectric layer on a substrate;

forming a polysilicon layer on the thin dielectric layer;

forming and patterning a solid-state p-type dopant source on the polysilicon layer, the patterning exposing regions of the polysilicon layer between a plurality of regions of the solid-state p-type dopant source;

loading the substrate in a reaction chamber and, without removing the substrate from the reaction chamber, both forming an n-type dopant source layer over the exposed regions of the polysilicon layer and the plurality of regions of the solid-state p-type dopant source and at least partially driving dopants from the n-type dopant source layer into the exposed regions of the polysilicon layer to form a plurality of n-type dopant-containing polysilicon regions between the plurality of regions of the solid-state p-type dopant source;

removing the substrate from the reaction chamber; and, subsequently,

heating the substrate to provide a plurality of n-type doped polysilicon regions among a plurality of p-type doped polysilicon regions.

12. The method of claim 11 , further comprising:

subsequent to forming an n-type dopant source layer and prior to heating the substrate, forming trenches between the plurality of n-type dopant-containing polysilicon regions and the plurality of regions of the solid-state p-type dopant source, the trenches formed in the polysilicon layer, in the thin dielectric layer, and partially in the substrate.

13. The method of claim 12 , further comprising:

subsequent to forming the trenches and prior to heating the substrate, texturizing portions of the substrate exposed by the trenches.

14. The method of claim 13 , wherein forming the trenches and the texturizing is performed without a cure operation between the forming the trenches and the texturizing.

15. The method of claim 11 , wherein forming the n-type dopant source layer further comprises at least partially driving dopants from the plurality of regions of the solid-state p-type dopant source into the polysilicon layer.

16. The method of claim 15 , wherein heating the substrate comprises activating the dopants in the plurality of n-type dopant-containing polysilicon regions, furthering the driving of dopants originating from the plurality of regions of the solid-state p-type dopant source into the polysilicon layer, and activating the dopants of the plurality of regions of the solid-state p-type dopant source in the polysilicon layer.

17. The method of claim 11 , further comprising:

while the substrate is loaded in the reaction chamber, at least partially driving dopants from the solid-state p-type dopant source into the polysilicon layer.

18. A solar cell fabricated according to the method of claim 11 .