EngineeringComputer EngineeringElectrical EngineeringMicroelectronicsSemiconductor DevicesVlsi DesignCmos Circuit DesignIntegrated Circuit DesignIntegrated Circuit DevicesIntegrated Circuit FabricationPhysical DesignVery-large-scale Integration Layout3D Integrated CircuitsCircuit IntegrationCmos Fabrication ProcessesRing OscillatorsSignal Propagation DelaySilicon-on-insulator CmosSilicon-on-insulator TechnologyThree-dimensional Integration
A 3-Dimensional (3-D) CMOS integration with a structure, in which one type of transistor is fabricated directly above a transistor of the opposite type with separate gates and an insulator in between, has successfully been fabricated by using laser beam recrystallization. Seven-stage ring oscillators fabricated in the 3-D structure have a propagation delay of 430psec per stage at a supply voltage of 5V, which is comparable to that of single-crystal Si devices. This CMOS structure and the process technologies we have developed in this work can be the basis for realizing a multi-layered 3-D integration composed of vertically stacked transistors with separate gates and an insulating layer in between.