Patent ID: 8329503

Claim:
A method of fabricating a photovoltaic solar cell, comprising: implanting a first plurality of regions of a {111}-oriented silicon wafer with a first dopant having a first doping type; implanting a second plurality of regions of the {111}-oriented silicon wafer with a second dopant having a second doping type opposite from the first doping type, the second plurality of regions being interspersed with the first plurality of regions; etching a first annular trench to a first depth partway through the {111}-oriented silicon wafer around the photovoltaic solar cell being formed; etching a plurality of openings partway through the {111}-oriented silicon wafer to a second depth greater than the first depth, the plurality of openings spaced around and outside of the first trench; depositing silicon nitride to fill the first trench and the plurality of openings; etching a second annular trench partway through the {111}-oriented silicon wafer to a third depth greater than the first depth, but less than the second depth, the second annular trench located about the first annular trench and the plurality of openings; and undercutting the photovoltaic solar cell being formed from the {111}-oriented silicon wafer by anisotropically etching the {111}-oriented silicon wafer laterally with the photovoltaic solar cell being attached to the {111}-oriented silicon wafer by the silicon nitride within the plurality of openings.