Solar cell contact formation using laser ablation

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

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

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

forming, by laser ablation, a plurality of contacts holes in the dielectric material, the plurality of the contact holes exposing P-type and N-type doped regions that are formed in the poly-crystalline material layer; and

forming conductive contacts in the plurality of contact holes, a first conductive contact of the conductive contacts being formed to electrically connect to a corresponding P-type doped region in the poly-crystalline material layer and a second conductive contact of the conductive contacts being formed to electrically connect to a corresponding N-type doped region in the poly-crystalline material layer.

2. The method of claim 1 , 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.

3. The method of claim 1 wherein forming the dielectric material above the poly-crystalline material layer comprises forming a stack of dielectric materials above the poly-crystalline material layer.

4. The method of claim 3 , wherein forming the stack of dielectric materials above the poly-crystalline material layer comprises forming a silicon dioxide layer on the poly-crystalline material layer, and forming a silicon nitride layer on the silicon dioxide layer.

5. The method of claim 4 , wherein the silicon dioxide layer is formed to have a thickness approximately in a range of 1-50 nanometers.

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

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

8. 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.

9. A method of fabricating a solar cell, the method comprising:

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

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

using a laser to form a contact hole in the dielectric material to form a recast poly signature in the poly-crystalline material layer, the contact hole exposing the recast poly signature in a doped region of the poly-crystalline material layer, the poly-crystalline material layer including P-type and N-type doped regions; and

forming a conductive contact in the contact hole, the conductive contact being coupled to the P-type doped region or the N-type doped region in the poly-crystalline material layer and in alignment with the recast poly signature.

10. The method of claim 9 , 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.

11. The method of claim 9 , wherein forming the dielectric material above the poly-crystalline material layer comprises forming a stack of dielectric materials above the poly-crystalline material layer.

12. The method of claim 11 , wherein forming the stack of dielectric materials above the poly-crystalline material layer comprises forming a silicon dioxide layer on the poly-crystalline material layer, and forming a silicon nitride layer on the silicon dioxide layer.

13. The method of claim 12 , wherein forming the silicon dioxide layer comprises forming the layer to have a thickness approximately in a range of 1-50 nanometers.

14. The method of claim 9 , wherein forming the dielectric material above the poly-crystalline material layer comprises forming only a silicon nitride layer.