Thermocompression bonding approaches for foil-based metallization of non-metal surfaces of solar cells
Thermocompression bonding approaches for foil-based metallization of non-metal surfaces of solar cells, and the resulting solar cells, are described. For example, a solar cell includes a substrate and a plurality of alternating N-type and P-type semiconductor regions disposed in or above the substrate. A plurality of conductive contact structures is electrically connected to the plurality of alternating N-type and P-type semiconductor regions. Each conductive contact structure includes a metal foil portion disposed in direct contact with a corresponding one of the alternating N-type and P-type semiconductor regions.
1. A method of fabricating a solar cell, the method comprising:
texturizing a surface of a metal foil, the texturized surface comprising valleys in the metal foil;
locating the texturized surface of the metal foil over a non-metalized surface of a wafer of the solar cell such that the texturized surface of the metal foil faces toward the non-metalized surface of the wafer of the solar cell; and
subsequent to the locating, electrically connecting the metal foil with the non-metalized surface of the wafer by thermocompression bonding, wherein metal from the metal foil flows in the valleys in the metal foil during the thermocompression bonding to form a metal flow region that fills and at least partially closes the valleys, and wherein the metal flow region is bonded directly to the non-metalized surface of the wafer.
2. The method of claim 1 , wherein the texturizing the surface of the metal foil comprises using a technique selected from the group consisting of brushing, embossing and etching.
3. The method of claim 1 , wherein the thermocompression bonding comprises applying a shear force to the metal foil.
4. The method of claim 1 , wherein the thermocompression bonding comprises applying a normal force to the metal foil.
5. The method of claim 1 , wherein the locating the metal foil with the non-metalized surface of the wafer comprises performing a tacking process.
6. The method of claim 1 , wherein the metal foil has a surface area substantially larger than a surface area of the wafer of the solar cell, the method further comprising:
subsequent to the electrically connecting the metal foil with the non-metalized surface of the wafer, cutting the metal foil to provide the metal foil having a surface area substantially the same as the surface area of the wafer of the solar cell.