Solar cell contact formation using laser ablation

1. A method of fabricating a back-contact solar cell, the method comprising:

forming a poly-crystalline material layer above a single-crystalline substrate;

forming a dielectric material stack above the poly-crystalline material layer;

forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and

forming conductive contacts in the plurality of contact holes;

wherein forming the poly-crystalline material layer above the single-crystalline substrate comprises forming a layer of poly-crystalline silicon above a single-crystalline silicon substrate, wherein forming the layer of poly-crystalline silicon above the single-crystalline silicon substrate comprises forming the layer of poly-crystalline silicon directly on a dielectric film, the dielectric film formed directly on the single-crystalline silicon substrate, and forming both N-type and P-type doped regions in the layer of poly-crystalline silicon.

2. The method of claim 1 , wherein forming the dielectric material stack above the poly-crystalline material layer comprises forming a silicon dioxide layer directly on the poly-crystalline material layer, and forming a silicon nitride layer directly on the silicon dioxide layer.

3. The method of claim 2 , wherein forming the silicon dioxide layer comprises forming the silicon dioxide layer to have a thickness approximately in the range of 1-50 nanometers.

4. The method of claim 1 , wherein forming the dielectric material stack above the poly-crystalline material layer comprises forming only a silicon nitride layer.

5. The method of claim 1 , wherein forming the plurality of contact holes is performed without the use of a patterned mask.

6. The method of claim 1 , wherein forming the plurality of contact holes comprises ablating with a laser having a wavelength approximately at, or less than, 1064 nanometers.

7. The method of claim 1 , wherein the poly-crystalline material layer comprises amorphous silicon.

8. A method of fabricating a back-contact solar cell, the method comprising:

forming a poly-crystalline material layer above a single-crystalline substrate;

forming a dielectric material stack above the poly-crystalline material layer;

forming a recast poly signature in the poly-crystalline material layer by ablating the dielectric material stack to form contact holes therethrough using a laser; and

forming a plurality of conductive contacts in the contact holes in the dielectric material stack and coupled directly to a portion of the poly-crystalline material layer, one of the conductive contacts in alignment with the recast poly signature;

wherein forming the poly-crystalline material layer above the single-crystalline substrate comprises forming a layer of poly-crystalline silicon above a single-crystalline silicon substrate, and wherein forming the layer of poly-crystalline silicon above the single-crystalline silicon substrate comprises forming the layer of poly-crystalline silicon directly on a dielectric film, the dielectric film formed directly on the single-crystalline silicon substrate, and forming both N-type and P-type doped regions in the layer of poly-crystalline silicon.

9. The method of claim 8 , wherein forming the dielectric material stack above the poly-crystalline material layer comprises forming a silicon dioxide layer directly on the poly-crystalline material layer, and forming a silicon nitride layer directly on the silicon dioxide layer.

10. The method of claim 9 , wherein forming the silicon dioxide layer comprises forming the silicon dioxide layer to have a thickness approximately in the range of 1-50 nanometers.

11. The method of claim 8 , wherein forming the dielectric material stack above the poly-crystalline material layer comprises forming only a silicon nitride layer.

12. The method of claim 8 , wherein each of the plurality of conductive contacts is round in shape.

13. The method of claim 8 , wherein forming the recast poly signature comprises ablating with a laser having a wavelength approximately at, or less than, 1064 nanometers.