US Patent 7776715 Reverse construction memory cell

A method of fabricating a memory cell comprises forming a plurality of doped semiconductor layers on a carrier substrate. The method further comprises forming a plurality of digit lines separated by an insulating material. The digit lines are arrayed over the doped semiconductor layers. The method further comprises etching a plurality of trenches into the doped semiconductor layers. The method further comprises depositing an insulating material into the plurality of trenches to form a plurality of electrically isolated transistor pillars. The method further comprises bonding at least a portion of the structure formed on the carrier substrate to a host substrate. The method further comprises separating the carrier substrate from the host substrate.