Fin-type PIN diode array

A PIN photodetector array, comprising:

• a first set of parallel silicon fins oriented in a first direction, doped with ions of a first electrical charge, and formed on a substrate;
• a second set of parallel polysilicon fins oriented to cross said first direction, doped with ions of a second electrical charge, and formed above said first set of parallel silicon fins;
• and
• a set of intrinsic semiconductor regions connecting each of said first set of parallel silicon fins and each of said second set of parallel polysilicon fins, where each of said parallel silicon fins and said parallel polysilicon fins cross each other in said PIN photodetector array.

A method, comprising:

• forming parallel silicon fins, doped with ions of a first electrical charge, on a planar substrate;
• forming polysilicon dummy gates at intervals along each silicon fin;
• forming undoped epitaxial silicon growths that alternate with said polysilicon dummy gates and exceed a height of each polysilicon dummy gate;
• depositing a polysilicon layer, doped with ions of a second electrical charge, that contacts an uppermost portion of each undoped epitaxial silicon growth;
• annealing said polysilicon layer to cause re-crystallization seeded from said uppermost portion each undoped epitaxial silicon growth;
• and
• patterning said polysilicon layer to form parallel polysilicon fins that are perpendicular to said parallel silicon fins, each of said parallel polysilicon fins contacting at intervals along its length said undoped epitaxial silicon growths, each of said undoped epitaxial silicon growths containing a depleted intrinsic region that contacts an overlying one of said parallel polysilicon fins and an underlying one of said parallel silicon fins, to form a single PIN structure in an array of PIN diodes.