Abstract: 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 P1 among the period P1, a period P2, 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 P1 and P2 and 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 P2 and 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A variable resistance nonvolatile memory device including memory cells provided at cross-points of first signal lines and second signal lines, each memory cell including a variable resistance element and a current steering element connected to the variable resistance element in series, the variable resistance nonvolatile memory device including a write circuit, a row selection circuit, and a column selection circuit, wherein the write circuit: sequentially selects blocks in an order starting from a block farthest from at least one of the row selection circuit and the column selection circuit and finishing with a block closest to the at least one of the row selection circuit and the column selection circuit; and performs, for each of the selected blocks, initial breakdown on each memory cell included in the selected block.

Abstract: 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.

Abstract: A method of writing data to a variable resistance element (10a) that reversibly changes between a high resistance state and a low resistance state according to a polarity of an applied voltage, as a voltage applied to an upper electrode (11) with respect to a lower electrode (14t): a positive voltage is applied in a high resistance writing step (405) to set the variable resistance element to a high resistance state (401); a negative voltage is applied in a low resistance writing step (406, 408) to set the variable resistance element to a low resistance state (403, 402); and a positive voltage is applied in a low resistance stabilization writing step (404) after the negative voltage is applied in the low resistance writing step, thereby setting the variable resistance element through the low resistance state to the high resistance state.

Abstract: 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.

Abstract: 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.

Abstract: Each of basic array planes has a first via group that interconnects only even-layer bit lines in the basic array plane, and a second via group that interconnects only odd-layer bit lines in the basic array plane, the first via group in a first basic array plane and the second via group in a second basic array plane adjacent to the first basic array in a Y direction are adjacent to each other in the Y direction, and the second via group in the first basic array plane and the first via group in the second basic array plane are adjacent to each other in the Y direction, and the second via group in the second basic array plane is disconnected from a second global line when connecting the first via group in the first basic array plane to a first global line.

Abstract: In a nonvolatile memory device, basic array planes (0 to 3) have respective first via groups (121 to 124) that interconnect only even-layer bit lines in the basic array planes, and respective second via groups (131 to 134) that interconnect only odd-layer bit lines in the basic array planes, the first via group in a first basic array plane and the second via group in a second basic array plane adjacent to the first basic array plane in a Y direction are adjacent to each other in the Y direction, and the first via group in the second basic array plane is connected to an unselected-bit-line dedicated global bit line (GBL_NS) having a fixed potential when the first via group in the first basic array plane is connected to a first global bit line related to the first basic array plane.

Abstract: 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.

Abstract: A cross point variable resistance nonvolatile memory device includes memory cells having the same orientation for stable characteristics of all layers. Each memory cell (51) is placed at a different one of cross points of bit lines (53) in an X direction and word lines (52) in a Y direction formed in layers. In a multilayer cross point structure where 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 (57, 58) switch electrical connection and disconnection between a global bit line (56) and commonly-connected even layer bit lines and commonly-connected odd layer bit lines, respectively. A bidirectional current limiting circuit (92) having parallel-connected P-type current limiting element (91) and N-type current limiting element (90) is provided between the global bit line and the switch elements.

Abstract: A nonvolatile resistance variable memory device (100) includes memory cells (M11, M12, . . . ) in each of which a variable resistance element (R11, R12, . . . ) including a variable resistance layer placed between and in contact with a first electrode and a second electrode, and a current steering element (D11, D12, . . . ) including a current steering layer placed between and in contact with a third electrode and a fourth electrode, are connected in series, and the device is driven by a first LR drive circuit (105a1) via a current limit circuit (105b) to decrease resistance of the variable resistance element while the device is driven by a second HR drive circuit (105a2) to increase resistance of the variable resistance element, thus using the current limit circuit (105b) to make a current for decreasing resistance of the variable resistance element lower than a current for increasing resistance of the variable resistance element.

Abstract: A variable resistance nonvolatile memory device including memory cells provided at cross-points of first signal lines and second signal lines, each memory cell including a variable resistance element and a current steering element connected to the variable resistance element in series, the variable resistance nonvolatile memory device including a write circuit, a row selection circuit, and a column selection circuit, wherein the write circuit: sequentially selects blocks in an order starting from a block farthest from at least one of the row selection circuit and the column selection circuit and finishing with a block closest to the at least one of the row selection circuit and the column selection circuit; and performs, for each of the selected blocks, initial breakdown on each memory cell included in the selected block.

Abstract: 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.

Abstract: An optimum forming method of performing a forming for a variable resistance element to maximize an operation window of the variable resistance element is provided. The forming method is used to initialize a variable resistance element (100). The forming method includes: a determination step (S35) of determining whether or not a current resistance value of the variable resistance element (100) is lower than a resistance value in a high resistance state; and a voltage application step (S36) of applying a voltage pulse having a voltage not exceeding a sum of a forming voltage and a forming margin when the determination is made that the current resistance value is not lower than the resistance value in the high resistance state (No at S35). The determination step (S35) and the voltage application step (S36) are repeated to process all memory cells in a memory array (202) (S34 to S37).

Abstract: A nonvolatile memory device of the present invention includes a substrate (1), first wires (3), first resistance variable elements (5) and lower electrodes (6) of first diode elements which are filled in first through-holes (4), respectively, second wires (11) which cross the first wires 3 perpendicularly to the first wires 3, respectively, and each of which includes a semiconductor layer (7) of a first diode elements, a conductive layer (8) and a semiconductor layer (10) of a second diode elements which are stacked together in this order, second resistance variable elements (16) and upper electrodes (14) of second diode elements which are filled into second through holes (13), respectively, and third wires (17), and the conductive layer (8) of each second wires (11) also serves as the upper electrode of the first diode elements (9) and the lower electrode of the second diode elements (15).

Abstract: 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.

Abstract: A method of writing data to a variable resistance element (10a) that reversibly changes between a high resistance state and a low resistance state according to a polarity of an applied voltage, as a voltage applied to an upper electrode (11) with respect to a lower electrode (14t): a positive voltage is applied in a high resistance writing step (405) to set the variable resistance element to a high resistance state (401); a negative voltage is applied in a low resistance writing step (406, 408) to set the variable resistance element to a low resistance state (403, 402); and a positive voltage is applied in a low resistance stabilization writing step (404) after the negative voltage is applied in the low resistance writing step, thereby setting the variable resistance element through the low resistance state to the high resistance state.