Silicon on insulator read-write non-volatile memory comprising lateral thyristor and trapping layer

Abstract

Disclosed herein is an improved thyristor-based memory cell. In one embodiment, the cell is formed in a floating substrate using Silicon-On-Insulator (SOI) technology. The cell preferably incorporates a lateral thyristor formed entirely in the floating substrate, and which is gated by a second word line. The cathode of the thyristor also comprises a source of an access transistor, whose drain is connected to the bit line of the device, and which is gated by a first word line. A trapping layer is built into the floating substrate, and when writing to the cell, pulses are added to cause holes to be trapped on the trapping layer for a logic state '1' and to cause electrons to be trapped on the trapping layer for a logic state '0'. Trapping of charges on the trapping layer adds extra margin to the stored data states, prevents their degradation, and renders the cell non-volatile.

Description

technical field [0001] The present invention relates to the design of memory cells for integrated circuits. Background technique [0002] There are many different types of memory cell designs in the art, each with its own advantages and disadvantages. For example, a dynamic random access memory (DRAM) cell includes a capacitor and an access transistor. The advantage of this cell design is that it can be made very dense. However, DRAM cells are volatile, meaning that the cells lose their stored data when power is removed from the device. Additionally, DRAM cells, even when powered, must be periodically refreshed to maintain their data state. The advantage of a static random access memory (SRAM) cell is that it can be accessed very quickly. However, SRAM cells draw larger amounts of current and are not very dense since they typically have 4 or 6 transistors in a single cell design. Furthermore, these cells, like DRAM cells, are also volatile. Electrically Erasable Progra...

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Problems solved by technology

[0013] Therefore, each of the above units has disadvantages that affect their applicability

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