Patent ID: 8735204

Claim:
A method for fabricating an electrical semiconductor device, the method comprising: applying a first optical energy to a semiconductor wafer comprising a semiconductor layer and a metallic back-contact material layer, wherein the first optical energy is oriented to penetrate the semiconductor layer to the metallic back-contact material layer, and wherein the first optical energy is controlled to match a first intensity profile that produces a uniform heating along an interface within the semiconductor wafer between the semiconductor layer and the metallic back-contact material layer; during application of the first optical energy: injecting vacancies into a crystalline lattice of the semiconductor layer by diffusing atoms of the semiconductor material into the metallic back-contact material layer; and melting an interfacial layer comprising silicon and Al alloy at the interface; during a cooldown, forming a backsurface field from the interfacial layer; after the cooldown: depositing a patterned layer of a metallic conducting material over an anti-reflective coating layer of the semiconductor wafer; applying a second optical energy to the semiconductor wafer, wherein the second optical energy is controlled to match a second intensity profile that produces a uniform heating between the layer of metallic conducting material and the anti-reflective coating layer; and during application of the second optical energy, firing the metallic conducting material through the anti-reflective coating layer to form a mechanical and electrical bond between the metallic conducting material and the semiconductor layer.