Sharp Kabushiki Kaisha Corporation

National Institute of Advanced Industrial Science and Technology

Elpida Memory, Inc.

Sharp Corporation

Yukio Tamai

Nobuyoshi Awaya

Kazuya Ishihara

Hidechika Kawazoe

Atsushi Shimaoka

Takashi Nakano

Shinobu Yamazaki

Yasunari Hosoi

Hiroyuki Akinaga

Hisashi Shima

Akihito Sawa

Fumiyoshi Takano

Hidetoshi Masuda

Shinji Kobayashi

Toshimasa Suzuki

Shigeo Ohnishi

Suguru Kawabata

Junya Onishi

Naoto Hagiwara

Yasuhiro Sugita

Yoshinao Morikawa

Takahiro Takimoto

Kazuhiro Natsuaki

Yusuke Jono

Hidenori Morimoto

Yushi Inoue

Koji Inoue

Akiyoshi Seko

Kohji Inoue

Daisuke Honda

Takuya Otabe

Yuji Matsushita

Yuji Nishi

Teruaki Morita

The image processing method includes a luminance value information obtaining step of obtaining effective radiance values from a subject, and an image generating step of generating a picture image as a set of unit regions each of which has a luminance value obtained by at least partially removing a regular reflection light component on a surface of the subject from the effective radiance values.

Image processing method and image processing device

A device including a memory cell including a variable resistive memory element; a capacitor; a voltage generation circuit; and a switch circuit including a first switch and a second switch. The first switch is coupled between the voltage generation circuit and the capacitor without an intervention of the second switch. The second switch is coupled between the capacitor and the memory cell without an intervention of the first switch. The first switch is configured to take an on-state during a first period of time and an off-state during a second period of time following the first period of time and the second switch is configured to take an off-state during the first period of time and an on-state during the second period of time.

Nonvolatile semiconductor memory device of variable resistive type with reduced variations of forming current after breakdown

A semiconductor memory device includes a memory cell array having a plurality of memory cells arranged in a matrix, each memory cell being configured such that a variable resistance element and a selection transistor are connected in series. A set operation for a memory cell (an operation of converting the resistance of the variable resistance element to a low resistance) is performed by applying a set voltage pulse for a longer time than that for a reset operation (an operation of converting the resistance of the variable resistance element to a high resistance) while limiting, using the selection transistor, an electric current flowing in the set operation to a certain low electric current, and by simultaneously applying the set voltage pulse to the plurality of memory cells.

Semiconductor memory device

A variable resistive element configured to reduce a forming voltage while reducing a variation in forming voltage among elements, a method for producing it, and a highly integrated nonvolatile semiconductor memory device provided with the variable resistive element are provided. The variable resistive element includes a resistance change layer (first metal oxide film) and a control layer (second metal oxide film) having contact with a first electrode sandwiched between the first electrode and a second electrode. The control layer includes a metal oxide film having a low work function (4.5 eV or less) and capable of extracting oxygen from the resistance change layer. The first electrode includes a metal having a low work function similar to the above metal, and a material having oxide formation free energy higher than that of an element included in the control layer, to prevent oxygen from being thermally diffused from the control layer.

Variable resistive element, method for producing the same, and nonvolatile semiconductor memory device including the variable resistive element

The invention provides a semiconductor memory device including a variable resistance element capable of decreasing a variation of a resistance value of stored data due to a large number of times of switching operations and capable of performing a stable writing operation. The device has a circuit that applies a reforming voltage pulse to a memory cell including a variable resistance element of a degraded switching characteristic and a small read margin due to a large number of times of application of a write voltage pulse, to return each resistance state of the variable resistance element to an initial resistance state. By applying the reforming voltage pulse, the variable resistance element can recover at least one resistance state from a variation from the initial resistance state, and can recover the switching characteristic. Accordingly, there is obtained a semiconductor memory device in which a reduction of a read margin is suppressed.

A variable resistance element that can stably perform a switching operation with a property variation being reduced by suppressing a sharp current that accompanies completion of forming process, and a non-volatile semiconductor memory device including the variable resistance element are realized. The non-volatile semiconductor memory device uses the variable resistance element for storing information in which a resistance changing layer is interposed between a first electrode and a second electrode, and a buffer layer is inserted between the first electrode and the resistance changing layer where a switching interface is formed. The buffer layer and the resistance changing layer include n-type metal oxides, and materials of the buffer layer and the resistance changing layer are selected such that energy at a bottom of a conduction band of the n-type metal oxide configuring the buffer layer is lower than that of the n-type metal oxide configuring the resistance changing layer.

Non-volatile semiconductor device

A large-capacity and inexpensive nonvolatile semiconductor memory device that prevents a leak current and is operated at high speed is implemented with a nonvolatile variable resistive element. A memory cell array includes the nonvolatile variable resistive elements each including a variable resistor composed of a metal oxide film to cause a resistance change according to an oxygen concentration in the film, an insulation film formed on the variable resistor, first and second electrodes to sandwich the variable resistor, and a third electrode opposite to the variable resistor across the insulation film. A writing operation is performed by applying a voltage to the third electrode to induce an electric field having a threshold value or more, in a direction perpendicular to an interface between the variable resistor and the insulation film, and a resistance state of the variable resistor is read by applying a voltage between the first and second electrodes.

Nonvolatile variable resistive element and nonvolatile semiconductor memory device

A memory cell array having a 1R structure is composed of nonvolatile variable resistive elements each including a variable resistor formed of a metal oxide film whose resistance changes depending on an oxygen concentration in the film, and first and second electrodes sandwiching the variable resistor. The first electrode and the variable resistor form a rectifier junction through a rectifier junction layer composed of an oxide layer and a layer (oxygen depletion layer) of the metal oxide film having an oxygen concentration lower than a stoichiometric composition. The oxygen moves between the first electrode and the metal oxide film when a voltage is applied, and a thickness of the oxygen depletion layer changes, so that the resistance of the metal oxide film changes and the rectifying properties are provided. A thickness of the oxygen depletion layer is set to allow the variable resistive element to show the sufficient rectifying properties.

Nonvolatile semiconductor memory device

A nonvolatile semiconductor memory device includes a memory cell array for storing user data provided by arranging memory cells each having a variable resistive element having a first electrode, a second electrode, and a variable resistor made of a metal oxide sandwiched between the first and second electrodes. The first and second electrodes are formed of a conductive material forming ohmic junction with the variable resistor and a conductive material forming non-ohmic junction with the variable resistor, respectively. The variable resistor changes between two or more different resistance states by applying a voltage between the electrodes. The resistance state after being changed is maintained in a nonvolatile manner. The variable resistive elements of all memory cells in the memory cell array are set to the highest of the two or more different resistance states in an unused state before the memory cell array is used to store the user data.

Provided is a variable resistive element which performs high speed and low power consumption operation. The variable resistive element comprises a metal oxide layer between first and second electrodes wherein electrical resistance between the first and second electrodes reversibly changes in accordance with application of electrical stress across the first and second electrodes. The metal oxide layer has a filament, which is a current path where the density of a current flowing between the first and second electrodes locally increases. A portion including at least the vicinity of an interface between the certain electrode, which is one or both of the first and second electrodes, and the filament, on an interface between the certain electrode and the metal oxide layer is provided with an interface oxide which is an oxide of at least one element included in the certain electrode and different from the oxide of the metal oxide layer.

Variable resistive element, manufacturing method for same, and non-volatile semiconductor memory device

A nonvolatile semiconductor memory device for suppressing a current consumption caused by a transient current because of the potential change of the bit and word lines at the time of shifting between the programming, reading, and erasing actions in a highly integrated memory cell array is provided. A memory cell () array comprises two-terminal memory cells each having a variable resistance element whose resistance value reversibly changes by pulse application are arranged in a row and column directions, wherein the memory cells in a row are connected at one end to common word lines (WLto WLn), the memory cells in a column are connected at the other end to common bit lines (BLto BLm), and a common unselected voltage V/2 is applied to both unselected word and bit lines not connected to the selected memory cell during the reading, programming, and erasing actions for the selected memory cell.

Nonvolatile semiconductor storage device and method for operating same

The present invention provides switching elements having a readout margin suitable for data storage units of nonvolatile memories, which are obtained by improving the resistance ratio of metal oxide thin films having reversible variable resistance properties. The present invention provides switching elements having a metal oxide consisting of a transition metal and oxygen formed between a first electrode and a second electrode, by modifying one or more of the crystal structure, ionic valence number of metal element, and nonstoichiometricity of a stoichiometric compound consisted of the transition metal and oxygen. The present invention also provides methods for producing switching elements having reversible variable resistance characteristics due to electric power application history.

Switching elements and production methods thereof

The variable resistance element of the present invention is a variable resistance element having an electrode, the other electrode, and a metal oxide material sandwiched between the electrodes and having an electrical resistance, between the electrodes, changing reversibly in response to a voltage applied between the electrodes. The variable resistance element further includes, inside the metal oxide material, a low resistance material having a lower electrical resistance than the metal oxide material and being out of contact with at least either one of the electrodes. This makes it possible to reduce a forming voltage for providing a conductive section inside the metal oxide material, without causing a leakage current to increase.

Variable resistance element, method for producing the same, and nonvolatile semiconductor storage device

A nonvolatile memory device comprises memory cells, each including a variable resistor element for storing data in accordance with a change in electrical resistance due to application of electrical stress, and a thermal diffusion barrier on a thermal diffusion path, wherein the thermal diffusion barrier is capable of suppressing a change in resistance of the variable resistor element due to heat diffusion from one of two adjacent memory cells separated by an electrical insulator from each other where heat is generated by applying the electrical stress for changing the electrical resistance of the variable resistor element to the other memory cell via the thermal diffusion path including an electrically conductive wiring material higher in thermal conductivity than that of the electrical insulator.

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Osaka, Japan

Yukio Tamai