JP2006032728A - Nonvolatile memory - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive, large storage capacity, low-crosstalk nonvolatile memory being driven with low power consumption and especially optimal as the memory of a portable apparatus, by providing a metal oxide having variable electric resistance between opposing electrodes. <P>SOLUTION: In the nonvolatile memory, having a cross-point memory structure or a three-dimensional structure, a metal oxide having variable electrical resistance is provided between opposing electrodes, and a field concentration portion is provided on the surface of at least one of the opposing electrodes touching the metal oxide. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In particular, the present invention relates to a nonvolatile memory that does not require a power source for holding records. More specifically, the present invention relates to a nonvolatile memory having a cross point structure.

  In recent years, with the rapid development of an advanced information society, devices and systems that handle data on high-speed and large-capacity information have become necessary. A nonvolatile memory has attracted attention as an element for storing the data at high speed.

  As the non-volatile memory, a flash memory and a ferroelectric memory (hereinafter referred to as FRAM) have already been put on the market and used for memory cards such as a mobile phone and a digital camera (hereinafter referred to as DSC). The unit price per 1 MB byte has already dropped below 0.15 US dollars, and the annual increase in capacity and cost has been realized. Until now, memory cards have been used as recording media for storing data for portable audio devices such as digital audio players and DSCs, and the market has been expanding.

  Recently, for example, an image signal obtained by recording a television broadcast program with a DVD recorder is recorded on a memory card, and the memory card is attached to a mobile phone, a portable information device, etc. Memory cards are increasingly used as a bridging medium used for data exchange between devices, such as playing back images on the network, which replaces wired and wireless networks, and uses networks Compared to the case, there is an advantage that the user can directly handle the medium as a real operation with a real operation, and the running cost is lower than the case where data is transmitted and received using a pay network such as a mobile phone.

  Furthermore, not only data storage memory but also development of memory cards with application software and hardware functions are being studied. When such memory cards are commercialized, not only memory and software, but also hardware However, it is no longer necessary to mount it on the device, and the device can be made smaller, lighter and thinner.

  Against this background, further reductions in bit cost (larger capacity and lower cost) and higher speed are required for nonvolatile memories.

  Here, Patent Document 1 discloses a nonvolatile memory having a cross-point memory structure. The device disclosed in Patent Document 1 has an external influence (in particular, between a plurality of lower electrodes provided on a substrate and a plurality of upper electrodes provided on the lower electrode orthogonal to the lower electrode. This is a non-volatile memory using a perovskite material whose electric resistance characteristics change due to an electric pulse, and has a cross-point memory structure with reduced crosstalk.

  Hereinafter, a nonvolatile memory having this cross-point memory structure will be described with reference to FIG.

  In FIG. 8, an upper electrode 63 is disposed orthogonal to the lower electrode 62 formed on the substrate 61, and a memory bit 64 made of a perovskite material is formed between the lower electrode 62 and the upper electrode 63. ing. The memory bit 64 is formed at all locations where the lower electrode 62 and the upper electrode 63 intersect. An insulating material 65 made of oxide is formed between the memory bits 64.

  The manufacturing method of the non-volatile memory having this cross-point memory structure is manufactured by the following steps (a) to (g).

(A) Step of providing a semiconductor substrate (b) Step of forming a plurality of lower electrodes (c) Step of forming an oxide insulating material on the lower electrode (d) Step of etching an opening with respect to the lower electrode (e) Forming a layer of perovskite material on the lower electrode and the oxide insulating material; (f) polishing the layer of perovskite material, leaving the perovskite material in the opening, and forming a memory bit; (g) layer of perovskite material Forming a plurality of upper electrodes on the substrate;
Japanese Patent Laid-Open No. 2003-68983

  However, the conventional non-volatile memory having the cross-point memory structure requires a complicated manufacturing process, increases the manufacturing cost, and it is difficult to reduce the bit cost.

  An object of the present invention is to provide a low-cost, large-capacity, low-crosstalk nonvolatile memory that is driven with low power consumption.

  A nonvolatile memory according to the present invention is a nonvolatile memory including a lower electrode disposed on a substrate, an upper electrode facing the lower electrode, and a metal oxide formed between the lower electrode and the upper electrode. In the memory, at least one of the opposing electrodes is provided with an electric field concentration portion on a surface in contact with the metal oxide.

  In addition, the nonvolatile memory of the present invention includes a plurality of lower electrodes disposed on a substrate in parallel at intervals within a substantially same plane, a plurality of upper electrodes facing the lower electrode, and the upper electrode A non-volatile memory including a metal oxide formed between the upper electrode and the lower electrode, wherein the upper electrode and the lower electrode are substantially orthogonal to each other, and at least one of the opposing electrodes has a metal oxide and An electric field concentration portion is provided on the contact surface.

  Furthermore, the non-volatile memory of the present invention has a plurality of electrodes arranged on a substrate in parallel and spaced apart in substantially the same plane, and an odd-numbered electrode among the plurality of electrodes. A non-volatile memory in which even-numbered electrodes are substantially orthogonal to each other and a metal oxide is provided between the odd-numbered electrodes and the even-numbered electrodes, wherein the opposing odd-numbered electrodes and even-numbered electrodes An electric field concentration portion is provided on a surface in contact with the metal oxide in at least one of the electrodes.

  In addition, the electric field concentration portion provided on the surface of at least one of the opposing electrodes in contact with the metal oxide is formed of a protrusion.

  The nonvolatile memory according to the present invention is characterized in that the cross-sectional shape of the electric field concentration portion of the electrode is a trapezoid, a triangle, a rectangle, a polygon, a substantially semicircular, a substantially semielliptical, or a combination of these shapes. .

  In the nonvolatile memory of the present invention, the metal oxide is a variable resistance material.

  The variable resistance material used in the nonvolatile memory of the present invention is preferably a metal oxide having an ilmenite structure, and the metal oxide having an ilmenite structure is a ferroelectric material.

  Furthermore, the nonvolatile memory of the present invention is a lithium niobate or lithium tantalate in which the metal oxide having an ilmenite structure contains at least one additive element of magnesium, indium, scandium, zinc, copper, and iron. It is characterized by being.

  The variable resistance material used in the nonvolatile memory of the present invention is preferably a metal oxide having a spinel structure, and the metal oxide having a spinel structure is magnesium titanate, chromium magnesium oxide, or chromic acid. It is any one of nickel, aluminum magnesium oxide, aluminum vanadate, and iron cobaltate.

  According to the nonvolatile memory of the present invention, the memory cell (memory region) is formed of a continuous layer of metal oxide and has a simple configuration in which an electric field concentration portion such as a protrusion is provided on at least one of the opposing electrodes. The advantage is that low-power consumption, low crosstalk, large storage capacity nonvolatile memory can be provided at low cost.

  Embodiments of a nonvolatile memory according to the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a cross-sectional view showing a configuration of a nonvolatile memory 10 according to Embodiment 1 of the present invention.

  A lower electrode 12 is disposed on a substrate 11 such as silicon or silicon whose surface is coated with silicon oxide, and a metal oxide (variable resistance material) 13 whose electric resistance value is changed by electric means on the lower electrode 12. The upper electrode 14 is further provided thereon. Projection 12a in the shape of a truncated cone (cross-sectional shape is trapezoidal) with the tip surfaces facing each other in the state of being embedded in the metal oxide 13 at the center of the opposing surface of the lower electrode 12 and the upper electrode 14 in contact with the metal oxide 13 , 14a are integrally provided.

  The protrusions 12a and 14a may be made of the same material or different materials as the electrodes 12 and 14, and may be provided simultaneously with the forming material when the electrodes 12 and 14 are formed. May be provided separately and integrated.

  The lower electrode 12 and the upper electrode 14 are connected to a word line or a bit line, but the electrodes themselves may be formed of a word line or a bit line. When the lower electrode 12 is the word line itself or connected to the word line, the upper electrode 14 is the bit line itself or connected to the bit line. In the opposite case, the lower electrode 12 is the bit line itself or connected to the bit line, and the upper electrode 14 is the word line itself or connected to the word line.

  Then, a voltage pulse or a current pulse is applied between the lower electrode 12 and the upper electrode 14 by electric means, so that the metal oxide 13 in the region where the projections 12a, 14a of the electrodes 12, 14 are in contact with each other. Digital information is stored by associating a high resistance state with a logic “0” and a low resistance state with a logic “1”.

  In the nonvolatile memory according to the present invention, when the electrodes 12 and 14 are provided with protrusions on the surface in contact with the metal oxide 13, when an electric field is applied between the electrodes, the electric field is concentrated on the protrusions 12a and 14a. For this reason, it can drive with low power consumption compared with the thing in which the protrusion is not provided in the electrode.

(Embodiment 2)
FIG. 2 is a cross-sectional view showing the configuration of the nonvolatile memory 20 according to Embodiment 2 of the present invention.

  In this nonvolatile memory 20, a plurality of lower electrodes 22 are arranged on a substrate 21 such as silicon or silicon whose surface is covered with silicon oxide in parallel and spaced apart in substantially the same plane. A continuous layer of a metal oxide 23 whose electrical resistance value is changed by applying an electric field by electrical means is formed thereon, and a plurality of upper electrodes arranged in parallel and spaced apart in substantially the same plane. 24 is provided. The lower electrode 22 and the upper electrode 24 are arranged substantially orthogonal to each other, and a cross-sectional shape in which the tip surfaces of the lower electrode 22 and the upper electrode 24 face each other in a state of being embedded in the metal oxide 23 in the center of the opposing surfaces of the intersecting regions. Trapezoidal protrusions 22a and 24a are provided.

  The protrusions 22a and 24a may be made of the same material as the electrodes 22 and 24, or may be made of a different material. At the time of forming the electrodes 22 and 24, the protrusions 22a and 24a may be formed simultaneously with the material. May be provided separately and integrated.

  The lower electrode 22 and the upper electrode 24 are connected to a word line or a bit line as in the first embodiment, but the electrodes themselves may be formed of a word line or a bit line. . When the lower electrode 22 is formed of the word line itself or connected to the word line, the upper electrode 24 is formed of the bit line itself or connected to the bit line. In the opposite case, the lower electrode 22 is formed by the bit line itself or connected to the bit line, and the upper electrode 24 is formed by the word line itself or connected to the word line.

  Then, in the plurality of lower electrodes 22 and upper electrodes 24, by applying a voltage pulse or a current pulse or the like between arbitrary electrodes by an electric means, a protrusion 22a located at the intersection of both electrodes to which the electric field is applied, Save digital information by changing the electrical resistance value of the metal oxide in the region in contact with 24a and associating the high resistance state with logic "0" and the low resistance state with logic "1" To do. That is, a region where the continuous layer of the metal oxide 23 and the protrusions 22a and 24a of both electrodes are in contact is a memory cell.

  Also in the second embodiment, as in the first embodiment, since the protrusions are provided on the surfaces of the electrodes in contact with the metal oxide, that is, the surfaces where the two electrodes intersect, when the electric field is applied between the electrodes, the protrusions The electric field concentrates on the part. Therefore, even if the metal oxide is a continuous layer, only the region where the metal oxide and the electrode protrusion are in contact becomes a memory cell that is not affected by crosstalk. Therefore, even when the interval between the plurality of electrodes is extremely narrow, the effect of crosstalk between memory cells can be reduced.

  In a low crosstalk nonvolatile memory having a cross-point memory structure, in a conventional nonvolatile memory, a memory bit is formed by providing an opening in a metal oxide such as a perovskite material at a position where a lower electrode and an upper electrode intersect. However, according to the configuration of the present invention described above, the step of forming the memory bit by providing the opening in the metal oxide becomes unnecessary, which reduces the manufacturing cost and lowers the bit cost. Can do. As in the first embodiment, it has an advantage that it can be driven with low power consumption as compared with a conventional nonvolatile memory in which a protruding portion is not provided on an electrode.

(Embodiment 3)
A non-volatile memory 30 having a three-dimensional structure according to Embodiment 3 of the present invention will be described with reference to FIG.

  This non-volatile memory 30 is an electrode in which a plurality of rod-shaped electrodes are arranged in parallel and at substantially the same plane on a substrate 31 such as silicon or silicon whose surface is covered with silicon oxide. The groups are arranged alternately in the direction perpendicular to the paper surface and in the left-right direction of the paper surface, and in these electrodes, the electrodes 321, 323. The electrodes 322, 324,... Are generally orthogonal to each other, and are continuous layers 331, 332 of metal oxide (variable resistance material) whose electric resistance value varies between each odd-numbered-stage electrode and even-numbered-stage electrode. , 333, 334..., And the tips of the respective electrodes are embedded in metal oxides 331, 332, 333, 334. surface Facing sectional shape trapezoidal protrusions 321a, 322a, 322b, 323a, 323b, 324a, it is 324b · · · are provided.

  In the example shown in FIG. 3, the uppermost electrode indicates an even-numbered electrode, but the uppermost electrode may be an odd-numbered electrode, and the odd-numbered electrodes facing each other. This is a non-volatile memory having a three-dimensional structure in which the protruding portions of the step electrode and the even-numbered step electrode are both connected to a metal oxide provided between these electrodes.

  The protrusions may be made of the same material as the electrode, or may be made of a different material, and may be provided simultaneously with the electrode forming material, or may be provided separately from the electrode and integrated. This also applies to Embodiments 4 and 5 described later.

  Each electrode is formed of a word line or a bit line itself, or is formed separately from and connected to the word line or the bit line, as in the first and second embodiments. Yes. If the electrodes in the odd-numbered stages are formed on the word lines themselves or connected to the word lines, the electrodes in the even-numbered stages are formed from the bit lines themselves or connected to the bit lines. Has been. In the opposite case, the odd numbered electrode is formed on the bit line itself or connected to the bit line, and the even numbered electrode is formed on the word line itself or connected to the word line. Is done.

  In the above configuration, a metal oxide in a region in contact with a protrusion located at the intersection of both electrodes to which the electric field is applied by applying a voltage pulse or a current pulse between any electrodes by an electric means. Digital information is stored by associating a high resistance state with a logic “0” and a low resistance state with a logic “1”. That is, the region where the electrode protrusion and the continuous layer of metal oxide are in contact is a memory cell.

  Also in this third embodiment, as in each of the above embodiments, since the protrusions are provided on the surface of the electrode that contacts the metal oxide, that is, the surface where the electrodes intersect, when an electric field is applied between the electrodes, Electric field concentrates. Therefore, even if the metal oxide is a continuous layer, only the region where the metal oxide and the electrode protrusion are in contact becomes a memory cell that is not affected by crosstalk. Therefore, even when the interval between the plurality of electrodes is extremely narrow, the effect of crosstalk between memory cells can be reduced.

  Since the protruding portion is provided on the electrode surface in contact with the metal oxide, when an electric field is applied between the electrodes, the electric field is concentrated on the protruding portion. Therefore, even if the metal oxide is a continuous layer, only the region where the metal oxide and the protruding portion of the electrode are in contact is a memory cell that is not affected by crosstalk. Therefore, even if the distance between the electrodes arranged in substantially the same plane is very narrow, the effect of crosstalk between memory cells can be reduced.

  Therefore, since the low crosstalk nonvolatile memory having the above three-dimensional structure is formed of a continuous layer of metal oxide, the manufacturing process cost can be reduced and the bit cost can be reduced. Further, since it has a three-dimensional structure, a nonvolatile memory with a large storage capacity and low power consumption can be provided.

  In the first, second, and third embodiments, the electrode protrusions are the lower electrode and the upper electrode, or the odd-numbered step and the even-numbered step, that is, the counter electrode in contact with the metal oxide. However, even if the protrusions are provided only on at least one side of the opposing electrode, the electric field concentrates on the protrusions. Only the region in contact with the memory cell becomes a memory cell that is not affected by crosstalk.

  In each of the above embodiments, the electrode protrusion has a trapezoidal cross-sectional shape. However, this cross-sectional shape is not limited to a trapezoidal shape, but is a triangle, rectangle, polygon, substantially semicircular, substantially A semi-elliptical shape or the like may be used, or a shape obtained by combining these shapes may be used as long as the electric field is concentrated on the protrusion when an electric field is applied between the electrodes.

(Embodiment 4)
Here, as an example of the shape of the protrusion that forms the electric field concentration portion, FIG. First, FIG. 4A shows a case where the cross-sectional shape of the electrode protrusion is a triangle, and FIG. 4B shows a case where the cross-sectional shape of the electrode protrusion is a substantially semi-elliptical shape. Reference numeral 42 in FIG. 4 is an electrode, and 42 a and 42 b are protrusions provided on the electrode 42.

(Embodiment 5)
In each of the above embodiments, the case where the protrusions of the electrodes are embedded in the metal oxide has been shown. However, the fifth embodiment is not embedded in the metal oxide and the tip portion is made of the metal oxide. Even in the contact structure, the electric field concentrates on the protrusion, and thus such a structure may be used.

  FIG. 5 shows an example of a structure in which the protrusions of the electrodes are not embedded in the metal oxide as in the above embodiments, and the tip portion is in contact with the metal oxide. In FIG. An electrode, 54 is a metal oxide, and 52a is a projection of the electrode. In addition, since others are the same as that of each embodiment, these are used and description is abbreviate | omitted.

(Embodiment 6)
A non-volatile memory having a three-dimensional structure according to Embodiment 6 of the present invention will be described with reference to FIGS. 6 is a cross-sectional view showing a configuration of the nonvolatile memory 100 according to Embodiment 6, and FIGS. 7A and 7B are cross-sectional views of electrodes.

  This nonvolatile memory 100 is formed by arranging a plurality of electrodes 1021 on a substrate 101 such as silicon or silicon whose surface is covered with silicon oxide in parallel and spaced apart in a substantially same plane by a sputtering method or the like. On top of that, a thin film of metal oxide 1031 is formed.

  This metal oxide 1031 thin film is formed by a vacuum deposition method, a sputtering method, a molecular beam epitaxial growth method (MBE), a cluster ion beam method (ICB), a physical deposition method (PVD) performed in a vacuum such as a laser ablation method, a vapor phase, or the like. Chemical transport method, metalorganic deposition transport method (MOCVD), plasma CVD method, vapor phase chemical deposition method (CVD) such as metal vapor chemical reaction method, and liquid phase epitaxial method (LPE) using melt and solution, printing It is formed by a liquid coating sintering method such as a sintering method, a sol-gel method, an organometallic decomposition method (MOD), or a spray method.

  Thereafter, a groove is formed on the upper surface of the metal oxide 1031, and a plurality of electrodes 1022 that are substantially orthogonal to the electrodes 1021 are formed in the grooves in parallel by the same method as the electrode 1021. A thin film of the oxide 1032 is formed by a method similar to that for the metal oxide 1031. The groove processing is performed by machining, laser beam irradiation, or cutting using light, an ion beam, an electron beam, or the like.

  Further, a plurality of electrodes 1023 are formed on the metal oxide 1032 in parallel with a space in substantially the same plane by a method similar to that of the lowermost electrode 1021, and the same as described above is formed on the electrode 1023. A thin film of metal oxide 1033 and an electrode 1024 are formed by the method, and are sequentially stacked in a multilayer structure by repeating the above method.

  Here, as for the electrode shape, the electrodes 1021, 1023... Are rectangular pillars having a rectangular cross section as shown in FIG. 7B, and the electrodes 1022, 1024. In this way, the hexagonal column has a cross-sectional shape, and the narrow flat surfaces of the hexagonal columns are arranged so as to face the electrodes 1021, 1023. concentrate. The shape of the electrodes 1022, 1024... Follows the processed shape of the groove, so that the groove shape is processed into a shape forming a hexagonal column.

  In the non-volatile memory 100 having a three-dimensional structure manufactured by the above manufacturing method, a plurality of electrodes are arranged on a substrate 101 in parallel at intervals within a substantially same plane, and these electrodes have steps. The electrodes 1021, 1023... In the odd-numbered steps and the electrodes 1022, 1024... In the even-numbered steps are substantially orthogonal to each other, and voltage pulses or current pulses are applied between the opposing electrodes by electrical means. Are applied to the memory cell regions 103, 104,... Made of metal oxide (variable resistance material).

  Each electrode is formed of the word line or the bit line itself, or is formed separately from the word line or the bit line and connected thereto, as in the above embodiments. If the electrodes in the odd-numbered stages are formed on the word lines themselves or connected to the word lines, the electrodes in the even-numbered stages are formed from the bit lines themselves or connected to the bit lines. Has been. In the opposite case, the odd numbered electrode is formed on the bit line itself or connected to the bit line, and the even numbered electrode is formed on the word line itself or connected to the word line. Is done.

  Then, by applying an electric field such as a voltage pulse or a current pulse between any electrodes by electrical means, the electric resistance value of the metal oxide in the memory cell regions 103, 104. By changing the electrical resistance value, the digital information can be stored by associating the high resistance state with logic “0” and the low resistance state with logic “1”.

  As described above, the electrodes 1022, 1024,... Have a hexagonal cross section, and when an electric field is applied between the electrodes, the electrodes 1022, 1024,. Since the electric field concentrates on the tip surface portion, it can be driven with low power consumption without being affected by crosstalk.

  This non-volatile memory having the three-dimensional structure is not affected by crosstalk, and a metal oxide such as a perovskite material is left in an opening at a position where opposing electrodes cross like a conventional non-volatile memory. Since the process of forming the bit is not necessary and the manufacturing process cost is reduced, the bit cost can be reduced. Further, since it has a three-dimensional structure, a nonvolatile memory with a large storage capacity and low power consumption can be provided.

  In the above description, the case where the cross-sectional shape of the electrodes 1022, 1024,... Is hexagonal has been described, but this cross-sectional shape is not limited to hexagonal, but is triangular, rectangular, polygonal, substantially semicircular, substantially semielliptical. The shape may be a shape, a combination of these shapes, or a combined shape, and may be an electric field concentration shape in which an electric field concentrates when an electric field is applied between the electrodes.

  The metal oxide in each of the above embodiments changes its electric resistance value by applying an electric field such as application of a voltage pulse or current pulse, application of DC voltage or DC current, application of AC voltage or AC current, or the like. Any metal oxide may be used, and in particular, one having a crystal structure such as a perovskite structure, an ilmenite structure, or a spinel structure is preferable. In the case of having a perovskite structure, a ferroelectric material, a giant magnetoresistance ( CMR) material and high-temperature superconducting (HTSC) material, and in particular, at least one of strontium barium titanate, strontium zirconate, praseodymium calcium manganate, and barium calcium gadolinium cobaltate. It is preferable. Furthermore, at least one or more additive elements may be contained among chromium, vanadium, scandium, and other transition metals.

  When the metal oxide has an ilmenite structure, it is preferably a ferroelectric material, lithium niobate containing at least one additional element of magnesium, indium, scandium, zinc, copper, and iron, or Lithium tantalate is preferred.

  Furthermore, when the metal oxide has a perovskite structure or an ilmenite structure, the concentration of the additive element is preferably more than 0 mol% and 10 mol% or less.

  Further, when the metal oxide has a spinel structure, it is preferably at least one of magnesium titanate, chromium magnesium acid, nickel chromate, aluminum magnesium acid, aluminum vanadate, and iron cobaltate.

  Each electrode in each of the above embodiments is a material that does not form a compound with a metal oxide, or a material that does not diffuse or chemically react with the metal oxide, and is made of platinum, gold, silver, copper, iridium, ruthenium, or aluminum. Of these, at least one of them is preferable.

  The thickness of each electrode and metal oxide in each of the above embodiments is preferably 10 nm to 1 μm, and the thickness of the silicon oxide is preferably 0.1 to 1 μm.

  Note that the substrate in each of the above embodiments is not limited to silicon, and is any one of lanthanum aluminate, lithium niobate, titanium nitride, or any other material that is amorphous, polycrystalline, or single crystal. Is a suitable substrate material.

  Furthermore, in each embodiment, an easily oxidizable material such as titanium or tantalum or an adhesion layer made of titanium oxide or tantalum oxide may be formed between the substrate and the lower electrode or the lowermost electrode. The thickness of the adhesion layer is preferably 10 nm to 100 nm. Further, the upper electrode or the uppermost electrode is preferably covered with an insulator such as aluminum oxide or silicon oxide. By covering with the insulator in this manner, the nonvolatile memory element can be used in terms of weather resistance. Can improve the reliability.

  An object of the present invention is to provide a low-cost, large-capacity, low-crosstalk nonvolatile memory that is driven with low power consumption, and is therefore most suitable as a memory for portable devices that handle a large amount of information.

It is sectional drawing which shows the structure of the non-volatile memory which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the structure of the non-volatile memory which concerns on Embodiment 2 of this invention. It is sectional drawing which shows the structure of the non-volatile memory which concerns on Embodiment 3 of this invention. It is sectional drawing of the protrusion part of the electrode which concerns on Embodiment 4 of this invention. It is sectional drawing which shows the relationship between the projection part of the electrode which concerns on Embodiment 5 of this invention, and a metal oxide. It is sectional drawing which shows the structure of the non-volatile memory which concerns on Embodiment 6 of this invention. (A), (b) is sectional drawing of the electrode which concerns on Embodiment 6 of this invention. It is sectional drawing of the conventional non-volatile memory.

Explanation of symbols

10, 20, 30, 100 Nonvolatile memory 11, 21, 31, 101 Substrate 12, 22 Lower electrode 12a, 22a Projection 14, 24 Upper electrode 14a, 24a Projection 321, 322, 323, 324, 42, 52, 1021, 1022, 1023, 1024 Electrodes 13, 23, 331, 332, 333, 334, 54 Metal oxides 321a, 322a, 322b, 323a, 323b, 324a, 324b Protrusions

Claims (11)

  A non-volatile memory comprising a lower electrode disposed on a substrate, an upper electrode facing the lower electrode, and a metal oxide formed between the lower electrode and the upper electrode. A non-volatile memory, wherein an electric field concentration portion is provided on a surface of at least one of the electrodes in contact with the metal oxide.   Formed on a substrate between a plurality of lower electrodes arranged in parallel and spaced apart in a substantially same plane, a plurality of upper electrodes opposed to the lower electrode, and the upper electrode and the lower electrode A non-volatile memory including a metal oxide, wherein the upper electrode and the lower electrode are substantially orthogonal to each other, and an electric field concentration portion is provided on a surface of at least one of the opposing electrodes that contacts the metal oxide Nonvolatile memory characterized by.   On the substrate, there are a plurality of stages of a plurality of electrodes arranged in parallel at intervals within a substantially same plane, and the odd-numbered electrodes and the even-numbered electrodes among the plurality of electrodes are substantially orthogonal to each other, A non-volatile memory in which a metal oxide is provided between the odd-numbered electrode and the even-numbered electrode, and the metal oxide of at least one of the opposed odd-numbered electrode and even-numbered electrode A non-volatile memory characterized in that an electric field concentration portion is provided on a contact surface.   4. The nonvolatile memory according to claim 1, wherein the electric field concentration portion provided on a surface of the at least one electrode of the opposing electrode that contacts the metal oxide is formed of a protrusion. 5.   The cross-sectional shape of the electric field concentration portion of the electrode is a trapezoidal shape, a triangular shape, a rectangular shape, a polygonal shape, a substantially semicircular shape, a substantially semielliptical shape, or a shape obtained by combining these shapes. The non-volatile memory in any one.   6. The nonvolatile memory according to claim 1, wherein the metal oxide is a variable resistance material.   The nonvolatile memory according to claim 6, wherein the variable resistance material is a metal oxide having an ilmenite structure.   The nonvolatile memory according to claim 7, wherein the metal oxide having an ilmenite structure is a ferroelectric material.   8. The metal oxide having an ilmenite structure is lithium niobate or lithium tantalate containing at least one additive element of magnesium, indium, scandium, zinc, copper, and iron. Nonvolatile memory as described in 1.   The nonvolatile memory according to claim 6, wherein the variable resistance material is a metal oxide having a spinel structure. The metal oxide having a spinel structure is any one of magnesium titanate, chromium magnesium acid, nickel chromate, aluminum magnesium acid, aluminum vanadate, and iron cobaltate. Non-volatile memory.

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