Sharp Kabushiki Kaisha Corporation

National Institute of Advanced Industrial Science and Technology

Xenogenic Development Limited Liability Company

National Science and Technology

Yasunari Hosoi

Kazuya Ishihara

Nobuyoshi Awaya

Takashi Nakano

Shigeo Ohnishi

Tetsuya Ohnishi

Yukio Tamai

Takahiro Shibuya

Shinji Kobayashi

Shinobu Yamazaki

Hiroyuki Akinaga

Hisashi Shima

Fumiyoshi Takano

Kenichi Tanaka

Yasushi Ogimoto

Shinichi Sato

Yushi Inoue

Kohji Inoue

Takashi Oka

Isao Inoue

Yoshinori Tokura

Takahiro Shibiuya

Naoto Nagaosa

A variable resistive element comprising a configuration that an area of an electrically contributing region of a variable resistor body is finer than that constrained by an upper electrode or a lower electrode and its manufacturing method are provided. A bump electrode material is formed on a lower electrode arranged on a base substrate. The bump electrode material is contacted to a variable resistor body at a surface different from a contact surface to the lower electrode. The variable resistor body is contacted to an upper electrode at a surface different from a contact surface to the bump electrode material. Thus, a cross point region between the bump electrode material (the variable resistor body) and the upper electrode becomes an electrically contributing region of the variable resistor body, and then an area thereof can be reduced compared with that of the region regarding the conventional variable resistive element.

Variable resistive element, and its manufacturing method

A nonvolatile semiconductor memory device include: a two terminal structured variable resistive element, wherein resistive characteristics defined by current-voltage characteristics at both ends transit between low and high resistance states stably by applying a voltage satisfying predetermined conditions to the both ends. A transition from the low resistance state to the high resistance state occurs by applying a voltage of a first polarity whose absolute value is at or higher than first threshold voltage, and the reverse transition occurs by applying a voltage of a second polarity whose absolute value is at or higher than a second threshold voltage. A load circuit is connected to the variable resistive element in series having an adjustable load resistance. A voltage generation circuit applies a voltage to both ends of a serial circuit. The variable resistive element can transit between the states by adjusting a resistance of the load circuit.

Nonvolatile semiconductor memory device

A nonvolatile semiconductor memory device comprises a memory cell array composed of a plurality of memory cells each including a variable resistance element in which a resistance characteristic is changed by applying a voltage to the both ends, and information related to the resistance characteristic can be stored; a load circuit connected to one terminal of the variable resistance element in series; and a voltage generation circuit for applying a voltage to both ends of a series circuit. The variable resistance element selectively transits to one resistance characteristic selected from at least three different resistance characteristics when the voltage generated from the voltage generation circuit is applied under the transition condition set by changing any one or both of the load resistance characteristic of the load circuit and the voltage generation condition from the voltage generation circuit, and can store information having at least three values.

Nonvolatile semiconductor memory device and writing method of the same

Provided are a variable resistive element having a configuration that the area of an electrically contributing region in a variable resistor body is smaller than the area defined by an upper electrode or a lower electrode, and a method for manufacturing the variable resistive element. The cross section of a current path, in which an electric current flows through between the two electrodes via the variable resistor body at the time of applying the voltage pulse to between the two electrodes, is formed with a line width of narrower than that of any of the two electrodes and of smaller than a minimum work dimension regarding manufacturing processes, so that its area can be made smaller than that of the electrically contributing region in the variable resistive element of the prior art.

Variable resistance element, and its manufacturing method

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 variable resistance element comprises a variable resistor of strongly-correlated material sandwiched between two metal electrodes, and the electric resistance between the metal electrodes varies when a voltage pulse is applied between the metal electrodes. Such a switching operation as the ratio of electric resistance between low and high resistance states is high can be attained by designing the metal electrodes and variable resistor appropriately based on a definite switching operation principle. Material and composition of the first electrode and variable resistor are set such that metal insulator transition takes place on the interface of the first electrode in any one of two metal electrodes and the variable resistor by applying a voltage pulse. Two-phase coexisting phase of metal and insulator phases can be formed in the vicinity of the interface between the variable resistor and first electrode by the work function difference between the first electrode and variable resistor.

Variable resistor element and its manufacturing method

Provided is a nonvolatile semiconductor device capable of performing writing operations of different resistance changes for memory cells having variable resistive elements whose resistive characteristics are changed by voltage applications, individually and simultaneously. The device includes: a load resistive characteristic variable circuit for each bit line connected commonly with the memory cells on the same column for selecting one of two load resistive characteristics according to a first writing operation where the resistive characteristics of the variable resistive element to be written transit from a low resistance state to a high resistance state or a second writing operation where they transit reversely; and a writing voltage pulse application circuit for applying a first voltage pulse in a first writing operation and a second voltage pulse in a second writing operation to the memory cells to be written through the load resistive characteristic variable circuits and the bit limes.

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 variable resistor element comprising a first electrode, a second electrode, and a variable resistor positioned between the first and second electrodes, and changing in electric resistance when a voltage pulse is applied between the both electrodes, has posed problems that it has a restriction of having to use noble metal electrodes as an electrode material and is not compatible with a conventional CMOS process. A variable resistor element using an oxynitride of transition metal element as a variable resistor exhibits a stable switching operation, is satisfactory in data retaining characteristics, and requires a small programming current. Since it does not necessarily require noble metal as an electrode material, it is high in compatibility with the existing CMOS process and easy to produce. It can be formed by a simple step of forming a variable resistor material into a film by oxidizing a lower electrode surface consisting of conductive nitride.

Variable resistor element, manufacturing method thereof, and memory device provided with it

Provided is a variable resistance element capable of performing a stable resistance switching operation and having a favorable resistance value retention characteristics, comprising a variable resistorsandwiched between a upper electrodeand lower electrodeand formed of titanium oxide or titanium oxynitride having a crystal grain diameter of 30 nm or less. When the variable resistanceis formed under the substrate temperature of 150&#xb0; C. to 500&#xb0; C., an anatase-type crystal having a crystal grain diameter of 30 nm or less is formed. Since the crystalline state of the variable resistor changes by applying a voltage pulse and the resistance value changes, no forming process is required. Moreover, it is possible to perform a stable resistance switching operation and obtain an excellent effect that the resistance fluctuation is small even if the switching is repeated, or the variable resistance element is stored for a long time under a high temperature.

Variable resistance element, its manufacturing method and semiconductor memory device comprising the same

A manufacturing method for a variable resistive element according to which a stable switching operation can be achieved with excellent reproducibility is provided. A conductive thin film is deposited on a semiconductor substrate and patterned to a predetermined form, and after that, a first interlayer insulating film is deposited. An opening is then created in a predetermined location on the first interlayer insulating film in such a manner that the upper surface of the conductive thin film is exposed and the thickness of the conductive thin film formed at the bottom of this opening is reduced through processing, and after that, an oxidation process is carried out on the periphery of the exposed conductive thin film. As a result, a variable resistor film is formed in the peripheral region of the opening, and this variable resistor film divides the conductive thin film into a first electrode and a second electrode.

Manufacturing method for variable resistive element

A nonvolatile semiconductor device is configured so that a load circuit applying voltage to a variable resistive element is provided electrically connecting in series to the variable resistive element, a load resistive characteristic of the load circuit can be switched between two different characteristics. The two load resistive characteristics are selectively switched depending on whether a resistive characteristic of the variable resistive element transits from low resistance state to high resistance state, or vice versa, voltage necessary for transition from one of the two resistive characteristics to the other is applied by applying writing voltage to a serial circuit of the variable resistive element and load circuit. After the resistive characteristic of the variable resistive element transits from one to the other, voltage applied to the variable resistive element does not allow a resistive characteristic to return from the other to one depending on the selected load resistive characteristic.

A variable resistance element is configured to be provided with a perovskite-type oxide between a first electrode and a second electrode, of which electric resistance between the first electrode and the second electrode is changed by applying a voltage pulse of a predetermined polarity between the first electrode and the second electrode, and the variable resistance element has a resistance hysteresis characteristic, in which a changing rate of a resistance value is changed from positive to negative with respect to increase of a cumulative pulse applying time in the application of the voltage pulse. The voltage pulse is applied to the variable resistance element so that the cumulative pulse applying time is not longer than a specific cumulative pulse applying time, in which the changing rate of the, resistance value is changed from positive to negative with respect to increase of the cumulative pulse applying time in the resistance hysteresis characteristic.

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Fukuyama, Japan

Yasunari Hosoi