SURFACE PREPARATION AND UNIFORM PLATING ON THROUGH WAFER VIAS AND INTERCONNECTS FOR PHOTOVOLTAICS
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Abstract
Photovoltaic devices are formed by laser drilling vias through silicon substrates and, following surface preparation of the via sidewalls, plating a continuous, electrically conductive layer on the via sidewalls to electrically connect the emitter side of the cell with the back side of the cell. The electrically conductive layer can be formed on portions of a base emitter within the vias and on the back side of the substrate. Alternatively, the electrically conductive layer can be formed on a passivation layer on the via sidewalls and back side of the cell.
11 Citations
19 Claims
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1-7. -7. (canceled)
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8. A method for fabricating a photovoltaic device, comprising:
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obtaining a substrate comprising silicon and including a front side and a back side; laser drilling one or more vias through the substrate, each of the one or more vias including a sidewall; smoothing the sidewall of each of the one or more vias; forming a doped emitter on the front side of the substrate; forming an electrically conductive contact pad on the back side of the substrate; forming an antireflective coating on the doped emitter, and plating a continuous, electrically conductive layer on each sidewall of the one or more vias, thereby forming one or more plated vias, each plated via having axial opening, whereby the continuous, electrically conductive layer of each of the one or more plated vias is electrically connected to the doped emitter; further including the steps of patterning emitter contacts on the front side of the substrate and plating the continuous, electrically conductive layer on the emitter contacts in addition to the sidewall; wherein the step of forming the doped emitter further includes forming a first portion of the doped emitter on the sidewall of each of the one or more vias and a second portion of the doped emitter on the front side of the substrate, the first and second portions of the doped emitter being continuous; further including forming a passivation layer on the sidewall of each of the one or more vias prior to plating the continuous, electrically conductive layer on each sidewall. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A photovoltaic device comprising:
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a base comprising silicon and having a front side and a back side; a doped base emitter adjoining the front side of the base; a doped, selective emitter adjoining the base emitter; an anti-reflective coating on the doped base emitter; one or more vias extending through the base and the doped, selective emitter, each of the one or more vias including a sidewall and an axial passage; an electrically conductive layer on the sidewall of each of the one or more vias and bounding the axial passage, the electrically conductive layer electrically connecting the doped, selective emitter and the back side of the base; a plated metal contact on the back side of the base, the plated metal contact being contiguous with the electrically conductive layer, and a base contact on the back side of the base, the plated metal contact and the base contact being electrically isolated from each other. - View Dependent Claims (16, 17, 18, 19)
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Specification