Patent ID: 8895372

Claim:
A method of forming a three-dimensional (3D) integrated circuit (IC) structure, the method comprising: forming a first layer of graphene over a substrate; forming a first level of one or more active devices using the first layer of graphene; forming an insulating layer over the first level of one or more active devices; forming a second layer of graphene over the insulating layer; and forming a second level of one or more active devices using the second layer of graphene, the second level of one or more active devices electrically interconnected with the first level of one or more active devices; wherein the one or more active devices of the first and second levels comprises field effect transistors having a bottom gate orientation relationship with respect to the associated graphene layer, and wherein the bottom gate orientation field effect transistors are formed by: forming openings in an associated insulating layer in accordance with a desired gate pattern; filling the openings in the associated insulating layer with a gate electrode material and planarizing the gate electrode material to form individual gate electrodes; forming a gate dielectric layer over the individual gate electrodes; forming the associated graphene layer over the gate dielectric layer; patterning the associated graphene layer and gate dielectric layer in accordance with a desired active layout area; forming one or more first level conductive pad structures adjacent the first layer of graphene such that a bottom surface of the one or more first level conductive pad structures is substantially co-planar with a bottom surface of the first layer of graphene; forming one or more second level conductive pad structures adjacent the second layer of graphene such that a bottom surface of the one or more second level conductive pad structures is substantially co-planar with a bottom surface of the second layer of graphene; and forming a plurality of source and drain contacts disposed on the graphene layers, above bottom oriented gate electrodes under the graphene layers.