Multi-junction solar cells with through-substrate vias

A method of forming a through-substrate via head comprising:

• providing a substrate having an epitaxial region grown thereon and a plurality of cap regions formed on top of the epitaxial region;
• depositing a photoresist region on the plurality of cap regions;
• etching a plurality of through-substrate vias from a backside of the substrate and using the photoresist region as an etch stop layer;
• depositing an electrically insulating liner within each of the plurality of through-substrate vias;
• removing the photoresist region to expose the plurality of cap regions;
• and
• depositing metal within the through-substrate vias to connect the plurality of cap regions.

A multi junction solar cell device comprising:

• a semi-insulating semiconductor substrate having a back surface;
• an epitaxial region overlying the semi-insulating semiconductor substrate;
• an electrically conductive semiconductor region between the substrate and the epitaxial region;
• at least one multi junction solar cell element formed in the epitaxial region, the epitaxial region being grown on the electrically conductive semiconductor region;
• a cap region overlying the epitaxial region;
• though-wafer vias that extend from the cap region to the back surface of the substrate;
• the cap region being shaped according to a cap pattern including collars around the through-wafer vias;
• conductive metal within the through-wafer vias and electrically connected to the cap patterned collars;
• an electrically insulating liner on the walls of the through-wafer vias insulating the conductive metal inside the through-wafer vias from at least the epitaxial region and from the conductive semiconductor region;
• an optical cover material disposed upon an optically transparent adhesive material directly above the through-substrate via heads formed on top of the epitaxial region;
• and
• a back metal on the back surface of the substrate in electrical contact with the conductive metal in the through-wafer vias.

A multi junction solar cell device comprising:

• an electrically conductive semiconductor substrate with at least one multi junction solar cell element formed in an epitaxial region grown thereon;
• a plurality of cap regions formed on top of the epitaxial region;
• through-substrate vias that extend from the plurality of cap regions to a back surface of the substrate;
• conductive metal within the through-substrate vias and electrically connected to the plurality of cap regions;
• an electrically insulating liner disposed on the walls of the through-substrate vias insulating the substrate and the epitaxial region from the conductive metal inside the through-wafer vias;
• a through-substrate via head that electrically connects the conductive metal within the through-substrate vias with the plurality of cap regions, henceforth called;
• a temporary carrier substrate bonded directly above the through substrate via heads formed on top of the epitaxial region;
• and
• a back metal, patterned with a back metal pattern, in ohmic contact with the back surface of the electrically conductive semiconductor substrate, and electrically isolated from the conductive metal within the through-substrate vias.

A method of forming a multi junction solar cell device, comprising:

• providing an electrically conductive semiconductor substrate with at least one multi-junction solar cell element formed in an epitaxial region grown thereon, and a plurality of cap regions formed on top of the epitaxial region;
• bonding a cover glass on top of the substrate and the plurality of cap regions;
• thinning the substrate;
• etching through-substrate vias from a back surface of the substrate;
• forming a patterned dielectric layer on the back surface of the substrate;
• and
• forming electrical connection between the patterned cap region and the back metal contacts pads with conductive metal inside the through-substrate vias, such that the contact pads are not directly electrically connected to the semiconductor substrate.

A method of forming a multi junction solar cell device, comprising:

• providing an electrically conductive semiconductor substrate with at least one multi-junction solar cell element formed in an epitaxial region grown thereon, and a patterned cap region formed on top of the epitaxial region;
• bonding a polymer cover on top of the substrate and the patterned cap region;
• thinning the substrate;
• etching through-substrate vias from a back surface of the substrate;
• forming a patterned dielectric layer on the back surface of the substrate;
• forming a plurality of back metal contact pads;
• and
• forming electrical connection between the patterned cap region and the back metal contacts pads with conductive metal inside the through-substrate vias, such that the contact pads are not directly electrically connected to the semiconductor substrate.