A system and method for fabricating a 3D image sensor structure is disclosed. The method comprises providing an image sensor with a backside illuminated photosensitive region on a substrate, applying a first dielectric layer to the first side of the substrate opposite the substrate side where image data is gathered, and applying a semiconductor layer that is optionally polysilicon, to the first dielectric layer. A least one control transistor may be created on the first dielectric layer, within the semiconductor layer and may optionally be a row select, reset or source follower transistor. An intermetal dielectric may be applied over the first dielectric layer; and may have at least one metal interconnect disposed therein. A second interlevel dielectric layer may be disposed on the control transistors. The dielectric layers and semiconductor layer may be applied by bonding a wafer to the substrate or via deposition.