Resistance-changing memory device

a memory device and resistive state technology, applied in the field of resistive state-changing memory devices, can solve the problems of degradation of the reliability of reram, inability to detect a resistive state during reading, and inability to influence the resistive value of a cell, so as to improve the reliability of data storag

Active Publication Date: 2012-01-31
KIOXIA CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0010]According to this invention, it is possible to provide the intended resistance change memory device with improved data storage reliability.

Problems solved by technology

However, in view of the fact that the state of a resistive body is determined by a voltage and heat to be applied to the resistive body, the resistance value of a cell becomes readily influenceable by disturbance occurring in access events.
In particular, the disturbance occurrable during reading by detection of a resistive state of a cell is inherently unavoidable to resistance change memories of the nondestructive read type, although such disturbance is less in magnitude.
Failure to devise this countermeasure would result in degradation of the reliability of ReRAM.

Method used

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Embodiment Construction

[0025]In this invention, in view of the nature of ReRAM that the resistive state of a memory cell is easily affectable by disturbance during reading, a refresh operation is performed after a read operation, for returning the cell's resistance value to an expected value. In the refresh operation, the characteristics of a resistance-changeable material of the cell are utilized to perform an operation which forces it to reach and stay at a fixed resistance value in a self-convergent manner. This refresh operation is performed by applying a voltage pulse to a selected cell after completion of data reading, thereby setting a voltage value and pulse width time of the voltage pulse in accordance with the resistance value, at which the self-convergence is aimed.

[0026]Prior to the explanation of an embodiment for practical implementation, a detailed explanation will be given of the disturbance that occurs due to readout of ReRAM. The disturbance during read-accessing poses problems in a case...

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Abstract

A resistance-changing memory device has a cell array having memory cells, each of which stores as data a reversibly settable resistance value, a sense amplifier for reading data from a selected memory cell in the cell array, and a voltage generator circuit which generates, after having read data of the selected memory cell, a voltage pulse for convergence of a resistive state of this selected memory cell in accordance with the read data.

Description

TECHNICAL FIELD[0001]This invention relates to resistance-changing memory devices.BACKGROUND ART[0002]A resistance-changing memory, such as resistive random access memory (ReRAM), uses a voltage, current, heat or else to reversibly change the resistance value of a material to thereby store as information a state different in resistance value of the material, and attracts attention as one of candidates for the replacement device of flash memories. The resistance change memory is suitable for microfabrication and has its ability to configure cross-point cell arrays; furthermore, this type of memory is easy to achieve a multilayered structure of cell array.[0003]As is known, there are two kinds of operation modes for a variable resistive element of ReRAM. One operation mode is to set a high resistive state and a low resistive state by switching the polarity of an applied voltage. This is called the bipolar type. The other operation mode is to enable setup of the high resistive state an...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): G11C11/00
Inventor TODA, HARUKI
Owner KIOXIA CORP
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