A memory cell with a small surface area is fabricated by forming source lines and data lines above and below and by running the channels to face up and down. The local data lines for each vertically stacked memory cell are connected to a global data line by way of separate selection by a molecular oxide semiconductor, and use of a large surface area is avoided by making joint use of peripheral circuits such as global data lines and sensing amplifiers by performing read and write operations in a timed multiplex manner. Moreover, data lines in multi-layers and memory cells (floating electrode cell) which are non-destructive with respect to readout are utilized to allow placement of memory cells at all intersecting points of word lines and data lines while having a folded data line structure. An improved noise tolerance is attained by establishing a standard threshold voltage for identical dummy cells even in any of the read verify, write verify and erase verify operations. A register to temporarily hold write data in a memory cell during writing is also used as a register to hold a flag showing that writing has ended during write verify. Also, a circuit comprised of one nMOS transistor is utilized as a means to change values on the write-end flag.
CROSS-REFERENCE TO RELATED APPLICATION
The present invention is a divisional application of Ser. No. 09/236,630, filed Jan. 26, 1999, now U.S. Pat. No. 6,040,605 which is a continuation-in-part application of a application Ser. No. 09/126,437 filed on Jul. 30, 1998 now U.S. Pat. No. 6,104,056, which are incorporated by reference herein its entirely.
A method (1110a;1110b) of refreshing an electrically erasable and programmable non-volatile memory (100) having a plurality of memory cells (Mhk) is proposed. The method includes the steps of: verifying (1106-1114; 1152-1162) whether a memory cell has drifted from a correct condition (i.e., a predetermined voltage and/or voltage range), and individually restoring (1116-1130) the correct condition of the memory cell if the result of the verification is positive.
A memory includes transistors in rows and columns providing an array and conductive lines in columns across the array. The memory includes phase change elements contacting the conductive lines and self-aligned to the conductive lines. Each phase change element is coupled to one side of a source-drain path of a transistor.
A two-transistor SRAM cell includes a first FET. The first FET is an ultrathin FET of a first polarity type and includes a control electrode, a first load electrode and a second electrode. The first load electrode is coupled to a first control line. The SRAM cell also includes a second FET. The second FET is an ultrathin FET of a second polarity type and includes a gate, a source and a drain. The second FET source is coupled to the first FET gate. The second FET gate is coupled to the first FET drain and the second FET source is coupled to a first potential. The SRAM cell further includes a first load device that is coupled between a second potential and the first FET gate. The SRAM cell additionally includes a second load device coupled between the second FET gate and a second control line.
A multi-stable memory or data storage element is used in crosspoint data-storage arrays, as a switch, a memory device, or as a logical device. The general structure of the multi-stable element comprises a layered, composite medium that both transports and stores charge disposed between two electrodes. Dispersed within the composite medium are discrete charge storage particles that trap and store charge. The multi-stable element achieves an exemplary bi-stable characteristic, providing a switchable device that has two or more stable states reliably created by the application of a voltage to the device. The voltages applied to achieve the "on" state, the "off" state, any intermediate state, and to read the state of the multi-stable element are all of the same polarity. The multi-stable element is stable, cyclable, and reproducible in both the "on" state and the "off" state. The storage medium has a relatively high resistance in both its on and off states. Consequently, a dense array can be fabricated without significant cross-talk between adjacent elements. No patterning of the layer of storage medium is required.
A multi-stable memory or data storage element is used in crosspoint data-storage arrays, as a switch, a memory device, or as a logical device. The general structure of the multi-stable element comprises a layered, composite medium that both transports and stores charge disposed between two electrodes. Dispersed within the composite medium are discrete charge storage particles that trap and store charge. The multi-stable element achieves an exemplary bi-stable characteristic, providing a switchable device that has two or more stable states reliably created by the application of a voltage to the device. The voltages applied to achieve the "on" state, the "off" state, any intermediate state, and to read the state of the multi-stable element are all of the same polarity.
