A method for making a semiconductor device comprises providing a first
wafer and providing a second wafer having a first side and a second side,
the second wafer including a semiconductor structure, a first storage
layer, and a layer of gate material, wherein the first storage layer is
located between the semiconductor structure and the layer of gate
material and closer to the first side of the second wafer than the
semiconductor structure. The method further includes bonding the first
side of the second wafer to the first wafer and cleaving away a first
portion of the semiconductor structure to leave a layer of the
semiconductor structure after the bonding. The method further includes
forming a second storage layer over the layer of the semiconductor
structure and forming a top gate over the second storage layer.