Local metallization for semiconductor substrates using a laser beam
Local metallization of semiconductor substrates using a laser beam, and the resulting structures, e.g., micro-electronic devices, semiconductor substrates and/or solar cells, are described. For example, a solar cell includes a substrate and a plurality of semiconductor regions disposed in or above the substrate. A plurality of conductive contact structures is electrically connected to the plurality of semiconductor regions. Each conductive contact structure includes a locally deposited metal portion disposed in contact with a corresponding a semiconductor region.
1. A method of fabricating a solar cell, the method comprising:
providing a substrate with an intervening layer thereon, the intervening layer including pre-formed openings to expose portions of the substrate;
locating a metal foil over the openings in the intervening layer; and
exposing the metal foil to a laser beam to form a conductive contact structure electrically connected to the substrate via the openings in the intervening layer, wherein the conductive contact structure includes a locally deposited metal portion of the metal foil, the locally deposited metal portion connected to an unexposed portion of the metal foil by a weakened structure of the metal foil, the weakened structure of the metal foil including patterning, subsequent to the exposing the metal foil to the laser beam, removing at least a portion of the metal foil not exposed to the laser beam, and to leave remaining the weakened structure of the metal foil including the patterning,
wherein the substrate comprises a plurality of N-type and P-type semiconductor regions, and wherein the openings in the intervening layer expose portions of the plurality of N-type and P-type semiconductor regions.
2. The method of claim 1 , wherein the locating the metal foil comprises locating a continuous sheet of the metal foil.
3. The method of claim 1 , wherein the removing at least a portion of the metal foil not exposed to the laser beam comprises forming an edge feature at an edge of the conductive contact structures.
4. The method of claim 1 , wherein the exposing the metal foil to the laser beam forms a spatter feature.
5. The method of claim 4 , further comprising removing the spatter feature.
6. The method of claim 1 , wherein the patterning includes perforation.