Multilevel transistor formation employing a local substrate formed within a shallow trench

Abstract

A dual level transistor and a fabrication technique. The dual level transistor is an integrated circuit in which a first transistor is formed on an upper surface of a global dielectric and a second transistor is formed on an upper surface of a first local substrate such that the second transistor is vertically displaced from the first transistor. The first local substrate is formed within a local trench etched into a first inter-substrate dielectric. By vertically displacing the first and second transistors, the lateral separation required to isolate first and second transistors in a typical single plane process is eliminated. The integrated circuit includes a semiconductor global substrate and a first transistor formed on the global substrate. The first transistor includes a first gate dielectric formed on an upper surface of the global substrate and a first conductive gate structure formed on an upper surface of the first dielectric. The integrated circuit further includes a first inter-substrate dielectric that is formed on the first conductive gate structure and the global substrate. The first inter-substrate dielectric includes a local trench. A first local substrate is formed within the local trench. A second transistor is located within the first local substrate. The second transistor includes a second gate dielectric formed on an upper surface of the first local substrate and a second conductive gate structure formed on an upper surface of the second gate dielectric.

Dependencies are inferred from the claim text.