American Semiconductor Corporation

Kelly James DeGregorio

Douglas R Hackler, Sr

Stephen A Parke

Dale G Wilson

Memory cells are constructed from double-gated four terminal transistors having independent gate control. DRAM cells may use one, two or three transistors. Single transistor cells are constructed either with or without a bit storage capacitor, and both NAND- and NOR-type Non-Volatile NVRAM cells, as well as Ferroelectric FeRAM cells, are described. For all cells, top gates provide conventional access while independent bottom gates provide control to optimize memory retention for given speed and power parameters as well as to accommodate hardening against radiation. In a single transistor cell without a capacitor, use of the bottom gate allows packing to a density approaching 2 F. Using a ferroelectric material as the gate insulator produces a single-transistor FeRAM cell that overcomes the industry-wide Write Disturb problem. The memory cells are compatible with SOI logic circuitry for use as embedded RAM in SOC applications.

Independently-double-gated transistor memory (IDGM)

A SRAM cell includes double-gated PMOS and NMOS transistors to form a latch and retain a value. The unique MOSFET transistor architecture provides a four terminal device for independent gate control, a floating body device, and a dynamic threshold device. The channel may have a U-shaped cross-sectional area to increase the channel length and gate control. First and second insulating spacers are disposed on opposing sides of the top gate such that the first spacer is between the source and the top gate, and the second spacer is between the drain and the top gate. The source and drain include extensions that extend proximate to the spacers and couple to the channel. The spacers shield the channel from the field effect of the source and drain, and further resist compression of the channel by the source and drain.

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Boise, ID, United States of America

Kelly James DeGregorio