Indentation approaches for foil-based metallization of solar cells

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

forming a plurality of alternating N-type and P-type semiconductor regions in or above a substrate;

locating a metal foil above the alternating N-type and P-type semiconductor regions;

forming a plurality of continuous indentations through only a portion of the metal foil, the plurality of indentations formed between and in a direction parallel with the alternating N-type and P-type semiconductor regions;

during the forming the plurality of continuous indentations, forming a continuous compression bond to bond the metal foil to the alternating N-type and P-type semiconductor regions, wherein forming the plurality of continuous indentations and the continuous compression bond is performed using raised features and a cylindrical base of a roller; and

subsequent to forming the plurality of indentations, isolating regions of remaining metal foil corresponding to the alternating N-type and P-type semiconductor regions.

2. The method of claim 1 , wherein forming the plurality of indentations comprises forming the plurality of indentations to a depth approximately in the range of 75-90% of an entire thickness of the metal foil.

3. The method of claim 1 , wherein forming the plurality of indentations comprises forming the plurality of indentations at a process temperature approximately in the range of 350-550 degrees Celsius.

4. The method of claim 1 , wherein isolating regions of remaining metal foil comprises etching the remaining metal foil at the locations between the alternating N-type and P-type semiconductor regions.

5. The method of claim 1 , wherein isolating regions of remaining metal foil comprises anodizing the remaining metal foil.

6. The method of claim 1 , wherein locating the metal foil above the alternating N-type and P-type semiconductor regions further comprises adhering the metal foil to the alternating N-type and P-type semiconductor regions using a technique selected from the group consisting of a laser welding process, a thermal compression process and an ultrasonic bonding process.

7. The method of claim 1 , wherein forming the plurality of alternating N-type and P-type semiconductor regions comprises forming the alternating N-type and P-type semiconductor regions in a polycrystalline silicon layer formed above the substrate, the method further comprising:

forming a trench between each of the alternating N-type and P-type semiconductor regions, the trenches extending partially into the substrate.

8. The method of claim 1 , wherein the substrate is a monocrystalline silicon substrate, and wherein forming the plurality of alternating N-type and P-type semiconductor regions comprises forming the alternating N-type and P-type semiconductor regions in the monocrystalline silicon substrate.

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

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

forming a plurality of alternating N-type and P-type semiconductor regions in or above a substrate;

locating a metal foil above the alternating N-type and P-type semiconductor regions;

forming a plurality of continuous indentations through only a portion of the metal foil, the plurality of indentations formed between and in a direction parallel with the alternating N-type and P-type semiconductor regions, wherein forming the plurality of indentations comprises forming the plurality of indentations to a depth approximately in the range of 75-90% of an entire thickness of the metal foil, and

wherein forming the plurality of indentations comprises forming the plurality of indentations at a process temperature approximately in the range of 350-550 degrees Celsius;

during the forming the plurality of continuous indentations, forming a continuous compression bond to bond the metal foil to the alternating N-type and P-type semiconductor regions, wherein forming the plurality of continuous indentations and the continuous compression bond is performed using raised features and a cylindrical base of a roller; and

subsequent to forming the plurality of indentations, isolating regions of remaining metal foil corresponding to the alternating N-type and P-type semiconductor regions.

11. The method of claim 10 , wherein isolating regions of remaining metal foil comprises etching the remaining metal foil at the locations between the alternating N-type and P-type semiconductor regions.

12. The method of claim 10 , wherein isolating regions of remaining metal foil comprises anodizing the remaining metal foil.

13. The method of claim 10 , wherein locating the metal foil above the alternating N-type and P-type semiconductor regions further comprises adhering the metal foil to the alternating N-type and P-type semiconductor regions using a technique selected from the group consisting of a laser welding process, a thermal compression process and an ultrasonic bonding process.

14. The method of claim 10 , wherein forming the plurality of alternating N-type and P-type semiconductor regions comprises forming the alternating N-type and P-type semiconductor regions in a polycrystalline silicon layer formed above the substrate, the method further comprising:

forming a trench between each of the alternating N-type and P-type semiconductor regions, the trenches extending partially into the substrate.

15. The method of claim 10 , wherein the substrate is a monocrystalline silicon substrate, and wherein forming the plurality of alternating N-type and P-type semiconductor regions comprises forming the alternating N-type and P-type semiconductor regions in the monocrystalline silicon substrate.

16. A solar cell fabricated according to the method of claim 13 .

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

forming a plurality of alternating N-type and P-type semiconductor regions in or above a substrate;

locating a metal foil above the alternating N-type and P-type semiconductor regions, wherein locating the metal foil above the alternating N-type and P-type semiconductor regions further comprises adhering the metal foil to the alternating N-type and P-type semiconductor regions using a technique selected from the group consisting of a laser welding process, a thermal compression process and an ultrasonic bonding process;

forming a plurality of continuous indentations through only a portion of the metal foil, the plurality of indentations formed between and in a direction parallel with the alternating N-type and P-type semiconductor regions;

during the forming the plurality of continuous indentations, forming a continuous compression bond to bond the metal foil to the alternating N-type and P-type semiconductor regions, wherein forming the plurality of continuous indentations and the continuous compression bond is performed using raised features and a cylindrical base of a roller; and

subsequent to forming the plurality of indentations, isolating regions of remaining metal foil corresponding to the alternating N-type and P-type semiconductor regions, wherein isolating regions of remaining metal foil comprises etching the remaining metal foil at the locations between the alternating N-type and P-type semiconductor regions.

18. The method of claim 17 , wherein forming the plurality of alternating N-type and P-type semiconductor regions comprises forming the alternating N-type and P-type semiconductor regions in a polycrystalline silicon layer formed above the substrate, the method further comprising:

forming a trench between each of the alternating N-type and P-type semiconductor regions, the trenches extending partially into the substrate.

19. The method of claim 17 , wherein the substrate is a monocrystalline silicon substrate, and wherein forming the plurality of alternating N-type and P-type semiconductor regions comprises forming the alternating N-type and P-type semiconductor regions in the monocrystalline silicon substrate.

20. A solar cell fabricated according to the method of claim 17 .