Iowa State University Research Foundation, Inc.

David H Schmidt

Howard R Shanks

Stanley G Burns

Allen R Landin

Carl Gruber

Alan Paul Constant

Allan P Constant

An integrated thin film transistor on insulator circuit made up of a number of thin film transistors formed with small feature size and densely packed so as to allow interconnection as a complex circuit. An insulating substrate, preferably flexible, serves as the support layer for the integrated circuit. Control gate metallization is carried on the insulating substrate, a dielectric layer is deposited over the control gate, and an amorphous silicon layer with doped source and drain regions deposited on the dielectric layer. Trenches are formed to remove the amorphous silicon material between transistors to allow highly dense circuit packing. An upper interconnect level which forms connections to the source and drain and gate regions of the thin film transistors, also interconnects the transistors to form more complex circuit structures. Due to the dense packing of the transistors allowed by the trench isolation, the interconnecting foils can be relatively short, increasing the speed of the circuit.

Method of making amorphous silicon on insulator VLSI circuit structures

A thin film floating gate transistor with improved dielectric structure. The dielectric structure serves the purpose of encapsulating the floating gate and also interfacing with the semiconductor material, .alpha.-Si:H. It thus must meet a variety of requirements. In order to provide long memory retention times, the dielectric material, at least in the regions encapsulating the floating gate, must have a high resistivity, on the order of 10.sup.17 ohm-cm or better. Silicon dioxide is the preferred material for encapsulating the floating gate. However, since silicon dioxide creates a high density of defect state when interfaced with the .alpha.-Si:H layer. An interface layer, substantially free of oxide, is interposed between the high resistivity layer and the .alpha.-Si:H. Preferably, the interface portion of the dielectric layer is silicon nitride. In some cases, it is desirable to replace the entire dielectric structure, or at least the interface layer with aluminum nitride.

Dielectric for amorphous silicon transistors

Amorphous silicon on insulator VLSI circuit structures

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Ames, IA, United States of America

David H Schmidt