Panasonic Corporation

Panasonic Intellectual Property Management Co., Ltd.

Matsushita Electric Industrial Co., Ltd.

Panasonic Corporaion

Ryotaro Azuma

Kazuhiko Shimakawa

Ken Kawai

Shunsaku Muraoka

Yoshikazu Katoh

Yuichiro Ikeda

Satoru Fujii

Yoshihiko Kanzawa

Akifumi Kawahara

Takeshi Takagi

Takumi Mikawa

Kenji Tominaga

Makoto Kojima

Zhiqiang Wei

Kiyotaka Tsuji

Kunitoshi Aono

Mitsuteru Iijima

Yuhei Yoshimoto

Hiroshi Tomotani

Yuuichirou Ikeda

Kouhei Tanabe

A semiconductor device includes a memory cell; circuitry that generates a reference voltage; and a sense amplifier including a first input terminal electrically connected to the memory cell, and a second input terminal electrically connected to the circuitry. The sense amplifier obtains a value in correlation with a resistance value of the memory cell based on a comparison between a sense voltage applied to the first input terminal and the reference voltage applied to the second input terminal. The sense voltage changes at a speed in correlation with the resistance value of the memory cell. In at least part of a period during which the sense voltage changes, the circuitry causes the reference voltage to change in a direction opposite to a direction in which the sense voltage changes.

Semiconductor device including memory cell and sense amplifer, and IC card including semiconductor device

A selection circuit that selects a memory cell from a memory cell array and a read circuit for reading a resistance state of a resistance change element in the selected memory cell are provided. In memory cells of odd-numbered-layer and even-numbered-layer memory cell arrays that constitute a multilayer memory cell array, each memory cell in any of the layers has a selection element, a first electrode, a first resistance change layer, a second resistance change layer, and a second electrode that are disposed in the same order. Whether the selected memory cell is located in any layer of the multilayer memory cell array, the read circuit applies a voltage to the selected memory cell to perform the reading operation. The voltage applied to the selected memory cell causes the second electrode to become positive with reference to the first electrode in the selected memory cell.

Read and write methods for a resistance change non-volatile memory device

A variable resistance nonvolatile memory device includes: a nonvolatile memory element; an NMOS transistor connected to the nonvolatile memory element; a source line connected to the NMOS transistor; a bit line connected to the nonvolatile memory element. When a control circuit causes the nonvolatile memory element to be in the low resistance state, the control circuit controls to flow a first current from a first voltage source to a reference potential point, and applies a first gate voltage to a gate of a NMOS transistor, and when the control circuit causes the nonvolatile memory element to be in the high resistance state, the control circuit controls to flow a second current from a second voltage source to the reference potential point, and applies a second gate voltage to the gate of the NMOS transistor, the second gate voltage being lower than the first gate voltage.

Variable resistance nonvolatile memory device including a variable resistance layer that changes reversibly between a low resistance state and a high resistance state according to an applied electrical signal

A nonvolatile memory device including a control unit configured to read resistance value information for each of memory cells as initial resistance value information and store it temporarily before a voltage pulse for forming is applied, to set resistance value information as a threshold value serving as a target for completion of the forming, the resistance value information being obtained by multiplying the initial resistance value information by a predetermined coefficient, and to repeat application of the voltage pulse for forming and reading of the resistance value information until a resistance value indicated by the resistance value information on the memory cell becomes lower than a resistance value indicated by the threshold value.

Variable resistance nonvolatile memory device and method of performing the forming operation

A cross point variable nonvolatile memory device includes a memory cell array including: first memory cells (e.g., part of a memory cell array) having a common word line; and second memory cells (e.g., another part of the memory cell array or a compensation cell unit). When a predetermined memory cell among the first memory cells is written to by changing the predetermined memory cell to a first resistance state, a word line write circuit supplies a first voltage or a first current to a selected word line, a first bit line write circuit supplies a third voltage or a third current to one bit line of the first memory cells, and a second bit line write circuit supplies the third voltage or the third current to A bit line or lines of the second memory cells.

Cross point variable resistance nonvolatile memory device and method of writing thereby

A cross-point memory device including memory cells each includes: a variable resistance element that reversibly changes at least between a low resistance state and a high resistance state; and a current steering element that has nonlinear current-voltage characteristics, and the cross-point memory device comprises a read circuit which includes: a reference voltage generation circuit which comprises at least the current steering element; a differential amplifier circuit which performs current amplification on an output voltage in the reference voltage generation circuit; a feedback controlled bit line voltage clamp circuit which sets the low voltage side reference voltage to increase with an output of the differential amplifier circuit; and a sense amplifier circuit which determines a resistance state of a selected memory cell according to an amount of current flowing through the selected memory cell.

Cross-point variable resistance nonvolatile memory device

The nonvolatile memory device includes a control circuit that controls a sense amplification circuit and a writing circuit. The control circuit changes a value of at least one of (a) a load current and (b) a forming pulse current or a forming pulse voltage, according to a total number of sneak current paths formed by memory cells each including a variable resistance element in a second resistance state having a low resistance value except a selected memory cell in a memory cell array.

Crosspoint nonvolatile memory device and method of driving the same

A cross point variable resistance nonvolatile memory device including: a cross point memory cell array having memory cells each of which is placed at a different one of cross points of bit lines and word lines; a word line decoder circuit that selects at least one of the memory cells from the memory cell array; a read circuit that reads data from the selected memory cell; an unselected word line current source that supplies a first constant current; and a control circuit that controls the reading of the data from the selected memory cell, wherein the control circuit controls the word line decoder circuit, the read circuit, and the unselected word line current source so that when the read circuit reads data, the first constant current is supplied to an unselected word line.

Cross point variable resistance nonvolatile memory device and method of reading thereby

A cross point nonvolatile memory device capable of suppressing sneak-current-caused reduction in sensitivity of detection of a resistance value of a memory element is provided. The device includes perpendicular bit and word lines; a cross-point cell array including memory cells each having a resistance value reversibly changing between at least two resistance states according to electrical signals, arranged on cross-points of the word and bit lines; an offset detection cell array including an offset detection cell having a resistance higher than that of the memory cell in a high resistance state, the word lines being shared by the offset detection cell array; a read circuit (a sense amplifier) that determines a resistance state of a selected memory cell based on a current through the selected bit line; and a current source which supplies current to the offset detection cell array in a read operation period.

Nonvolatile semiconductor memory device and read method for the same

A method of inspecting a variable resistance nonvolatile memory device detecting a faulty memory cell of a memory cell array employing a current steering element, and a variable resistance nonvolatile memory device are provided. The method of inspecting a variable resistance nonvolatile memory device having a memory cell array, a memory cell selection circuit, and a read circuit includes: determining that a current steering element has a short-circuit fault when a variable resistance element is in a low resistance state and a current higher than or equal to a predetermined current passes through the current steering element, when the resistance state of the memory cell is read using a second voltage; and determining whether the variable resistance element is in the low or high resistance state, when the resistance state of the memory cell is read using a first voltage.

Method of inspecting variable resistance nonvolatile memory device and variable resistance nonvolatile memory device

A sense amplification circuit includes a sneak current compensating load current supply unit that selectively switches a load current among load currents having different current amounts and supplies the load current to a bit line selected by a column selection circuit. The sense amplification circuit outputs 'L' level when a current amount of the load current is more than a reference current amount, and outputs 'H' level when the current amount is less than the reference current amount. A control circuit adjusts the current amount to a predetermined current amount that causes the sense amplification circuit to output &#x2018;H&#x2019; level. After the adjustment, the control circuit performs control to supply the load current having the predetermined current amount and controls the writing unit to keep the application until the sense amplification circuit outputs &#x2018;L&#x2019; level.

Crosspoint nonvolatile memory device and forming method thereof

Provided is a variable resistance nonvolatile memory device that achieves, in multi-bit simultaneous writing for increasing a writing speed, writing with little variation caused by positions of memory cells in multi-bit simultaneous writing. The variable resistance nonvolatile memory device includes bit lines, word lines, memory cells, a first write circuit (e.g., a write circuit (-)), a second write circuit (e.g., a write circuit (-k&#x2212;1)), a first selection circuit (e.g., a selection circuit (S)), a second selection circuit (e.g., a selection circuit (S_k&#x2212;1)), and a first word line drive circuit (a word line drive circuit (-)), wherein the first selection circuit (e.g., an NMOS transistor (TSto TS_m&#x2212;1) included in the selection circuit) has a greater ON resistance than the second selection circuit (e.g., an NMOS transistor (TS_k&#x2212;1to TS_k&#x2212;1_m&#x2212;1) included in the selection circuit) does.

Variable resistance nonvolatile memory device and method of writing thereby

Each memory cell is formed at a different one of cross points of bit lines extending in an X direction and formed in a plurality of layers and word lines extending in a Y direction. In a multilayer cross point structure in which a plurality of vertical array planes sharing the word lines are aligned in the Y direction each for a group of bit lines aligned in a Z direction, even and odd layer bit line selection switch elements switch connection and disconnection between a global bit line and the commonly-connected even layer bit line and the commonly-connected odd layer bit line, respectively. Each of the even and odd layer bit line selection switch elements has both a bit line selection function and a current limiting function in low resistance writing.

Cross point variable resistance nonvolatile memory device

A cross-point variable resistance nonvolatile memory device comprises: a memory cell array; a column decoder and pre-charge circuit which pre-charges a selected word line to a first voltage in a period Pamong the period P, a period P, and a period S that are included in this order in a read operation of a memory cell; a low decoder driver which pre-charges a selected word line to the first voltage in the periods Pand Pand sets the selected word line to a third voltage different from the first voltage in the period S; a feedback controlled bit line voltage clamp circuit which sets the selected bit line to a second voltage in the periods Pand S; and a sense amplifier which determines the resistance state in a memory cell at a cross-point of the selected word line and the selected bit line in the period S.

Cross-point variable resistance nonvolatile memory device and reading method for cross-point variable resistance nonvolatile memory device

A variable resistance nonvolatile memory device includes: bit lines in layers; word lines in layers formed at intervals between the layers of the bit lines; a memory cell array including basic array planes and having memory cells formed at crosspoints of the bit lines in the layers and the word lines in the layers; global bit lines provided in one-to-one correspondence with the basic array planes; and sets provided in one-to-one correspondence with the basic array planes, and each including a first selection switch element and a second selection switch element, wherein memory cells connected to the same word line are successively accessed in different basic array planes, and memory cells are selected so that voltages applied to the word line and bit lines are not changed and a direction in which current flows through the memory cells is the same.

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Osaka, Japan

Ryotaro Azuma