KR101515754B1 - Bi-Sb based resistive switching memory and method for producing the same - Google Patents

Abstract

The present invention relates to a BI_1-xSb_x based resistive switching memory and a method for producing the same, and provides a BI_1-xSb_x based resistive switching memory and a method for producing the same without a necessity of a foaming process and use of a metal oxide.

Description

[0001] The present invention relates to a bismuth-antimony-based resistive memory device and a manufacturing method thereof,

It relates to a _{- (x} Sb _x Bi ₁₎ based resistance memory element and a method of manufacturing the-present invention-resistance memory device and relates to a manufacturing method, and more particularly, bismuth requires no forming process is not a metal oxide, antimony .

The memory records, deletes and reads binary information using physical properties such as electrical, magnetic, and optical properties of the material. A Resistive Random Access Memory (ReRAM), which is one of the next generation non-volatile memories, is a memory device capable of recording, deleting and reading information by a change in the resistance of a material, and includes MRAM (Magnetic RAM) (Ferroelectric random access memory), PRAM (phase change RAM), and other nonvolatile memory devices, the structure is simple and the input / output speed is fast.

Until now, most of the ReRAMs are based on metal oxides, and for forming the forming process, a large voltage application is required. Specifically, the resistance change memory phenomenon has been observed mainly in metal oxides such as NiO _x , VO ₂ , Ta ₂ O ₅ , Nb ₂ O ₅ and TiO ₂ . Reversible switching < / RTI > state.

In the reversible switching state, the resistance change memory phenomenon is caused by a voltage of the same polarity and a voltage of a different polarity from that of the unipolar switching which is switched between the 'off' state having a high resistance and the 'on' state having a low resistance And 'bipolar switching' which can be switched to 'off' state. Unipolarity and bipolar switching have advantages and disadvantages, respectively. Unipolar switching has a large on / off ratio, but the reproducibility of switching parameters such as V _SET and V _RESET is low. On the other hand, in the case of bipolar switching, the on / off ratio is lower than unipolar switching. The reproducibility of the switching parameters is relatively high.

Thus, not the object is a metal oxide of the present invention, bismuth does not require the forming process, - to provide a _{- (x} Bi _x Sb ₁₎ resistance based memory element and a method of antimony.

In order to achieve the above object, the present invention provides a resistive memory device comprising a bismuth-antimony material represented by the following general formula (1).

[Chemical Formula 1]

Bi _{1 - x} Sb _x

Where x is 0.22 to 0.3.

The resistance memory element according to the present invention may have a bipolar switching characteristic.

In the present invention, the bismuth-antimony material may have a nanowire or a thin film form.

In the present invention, the diameter of the nanowires may be 10 to 200 nm.

A resistive memory device according to an embodiment of the present invention includes a substrate; A bismuth-antimony material formed on the substrate; And a plurality of electrodes formed on the substrate and connecting the bismuth-antimony material.

According to another aspect of the present invention, there is provided a resistance memory device comprising: a substrate; A lower electrode formed on the substrate; A bismuth-antimony material formed on the lower electrode; And an upper electrode formed on the bismuth-antimony material.

In the present invention, the bismuth-antimony material may be composed of a single nanowire or a nanowire array including a plurality of nanowires.

In the present invention, the substrate may be silicon, a polyimide film, or a polyester film.

In the present invention, each of the electrodes may be independently selected from the group consisting of Au, Pt, and Ti.

The present invention also provides a method of fabricating a resistive memory device comprising forming a bismuth-antimony material of Formula 1 on a substrate.

[Chemical Formula 1]

Bi _{1 - x} Sb _x

Where x is 0.22 to 0.3.

In the present invention, the bismuth-antimony material may be formed by electroplating using a bismuth precursor and an antimony precursor.

Wherein the bismuth precursor in the present invention, _{Bi (NO 3) 3, Bi} (NO 3) 3 · 5H 2 O, BiNBO 4, Bi 2 VO 5, BiR 1 2 (R 1 2 NCH 2 R 2), BiBr 3, BiCl _{3, BiF 3, Bi 2 (} Al 2 O 4) 3 · xH 2 O, Bi (OCOC (CH 3) 2 (CH 2) 5 CH 3) 3, Bi (O) NO 3, Bi 5 O (OH) _{9 (NO 3) 4, (} CH 3 CO 2) 3 Bi, (BiO) 2 CO 3, [O 2 CCH 2 C (OH) (CO 2) CH 2 CO 2] Bi, C 7 H 5 BiO 6 · xH ₂ O, BiI ₃ , Bi ₂ (MoO ₄ ) ₃ , Bi ₂ O ₃ , BiClO, BiIO, BiO ₄ P and HOC ₆ H ₄ COOBiO, 1 to 20, and R ¹ and R ² each independently may be an alkyl group, an alkylene group, an aryl group or an arylene group having 1 to 20 carbon atoms.

In the present invention, the antimony precursor may be SbCl ₃ , SbCl ₅ , Sb (NO ₃ ) ₃ , _{Sb (NO 3) 3 · 5H} 2 O, SbBr 3, SbF 3, Sb 2 (Al 2 O 4) 3 · xH 2 O, Sb (OCOC (CH 3) 2 (CH 2) 5 CH 3) 3, Sb _{(O) NO 3, Sb 5} O (OH) 9 (NO 3) 4, (CH 3 CO 2) 3 Sb, (SbO) 2 CO 3, [O 2 CCH 2 C (OH) (CO 2) CH 2 CO ₂ Sb, C ₇ H ₅ SbO ₆ .xH ₂ O, SbI ₃ , SbI ₄ , Sb ₂ (MoO ₄ ) ₃ , Sb ₂ O ₃ , SbClO, SbIO, SbO ₄ P, HOC ₆ H ₄ COOSb, Sb (R ³ ) ₃ and Sb [N (R ⁴ ) ₂ ] ₃ , wherein x is 1 to 20, R ³ and R ⁴ each independently represent a C 1-20 An alkylene group, an aryl group or an arylene group.

In the present invention, the bismuth-antimony material may be formed in a nanowire form using porous aluminum oxide formed through anodic oxidation as a template.

According to the present invention, since Bi _{1 - x} Sb _x exhibiting semi-metal characteristics of x> 0.22 exhibits a resistance change memory characteristic, it can respond to a resistance memory device. Unlike a metal oxide device whose initial state is in an insulated state, Bi _{1 - x} Sb _x can be switched without a forming process requiring a high voltage application since the initial state is an on state with a small resistance.

1 schematically shows a manufacturing process of a single nanowire device according to an embodiment of the present invention.
2 is an electron micrograph of a Bi _{1 - x} Sb _x nanowire (left) and a fabricated single nanowire device (right) manufactured according to one embodiment of the present invention.
FIG. 3 is a graph showing transmission electron microscopy (TEM) analysis (left), X-ray spectroscopy (left inside), scanning transmission electron microscope (STEM) data of Bi _{1 - x} Sb _x nanowires prepared according to an embodiment of the present invention (Right).
4 is an IV characteristic curve of a single nanowire device fabricated according to an embodiment of the present invention.
5 is a schematic diagram of a fabrication process of a nanowire array device according to another embodiment of the present invention.
FIG. 6 is an electron micrograph of the top (left) and side (right) sides of a nanowire array of a nanowire array device manufactured according to another embodiment of the present invention. FIG.
7 is a graph showing resistance change characteristics of a highly integrated nanowire device fabricated according to another embodiment of the present invention.

Hereinafter, the present invention will be described in detail.

The present invention is bi-directed to a _{- (x} Bi _x Sb ₁₎ resistance based memory element and a method of antimony.

The resistive memory device according to the present invention comprises a bismuth-antimony material having the following formula (1).

[Chemical Formula 1]

Bi _{1 - x} Sb _x

In the above formula, x is preferably 0.2 to 0.7, more preferably 0.2 to 0.5, and most preferably 0.22 to 0.3. If x is less than 0.2, resistance change memory characteristics do not appear.

The resistance memory device according to the present invention may have a bipolar switching characteristic.

Specifically, the initial state of the resistance memory element according to the present invention is switched to an on state having a first resistance value, an off state having a second resistance value greater than a first resistance value at a negative voltage, And may be switched to an on state having a third resistance value that is less than the resistance value.

In the present invention, the first resistance value may be 100 Ω to 100 kΩ. In the case of the conventional metal oxide device, the initial state was in an insulated state, and the resistance value of the initial state of the existing device was more than 100 MΩ. In contrast, since the initial state of the device according to the present invention is an on state having a small resistance, switching can be performed without a forming process requiring high voltage application.

In the present invention, the second resistance value may be 1 MΩ to 100 MΩ, and the third resistance value may be 100Ω to 100 kΩ.

In the present invention, the negative voltage may be between -0.5 and -2.0 V, and the positive voltage may be between 0.5 and 2.0 V. The voltage at which the switching is performed can be changed as needed within the above range.

In the present invention, the shape of the Bi _{1 - x} Sb _x resistance change material is not particularly limited and may have a nano wire or a thin film shape, for example.

In the present invention, the diameter of the nanowires is not particularly limited, and may be, for example, 10 to 200 nm.

A resistive memory device according to an embodiment of the present invention includes a substrate; A Bi _{1 - x} Sb _x resistance variable material formed on the substrate; And a plurality of electrodes formed on the substrate and connecting the Bi _{1 - x} Sb _x resistance variable material.

According to another aspect of the present invention, there is provided a resistance memory device comprising: a substrate; A lower electrode formed on the substrate; A Bi _{1 - x} Sb _x resistance variable material formed on the lower electrode; And an upper electrode formed on the Bi _{1 - x} Sb _x resistance variable material.

In the present invention, the Bi _{1 - x} Sb _x resistance change material may be composed of a single nanowire or a nanowire array including a plurality of nanowires when the nanowire is used.

In the present invention, the material of the substrate is not particularly limited, and for example, silicon, a polyimide film, a polyester film, or the like can be used.

In the present invention, the material of the electrode is not particularly limited and at least one selected from the group consisting of Au, Pt and Ti may be used. The materials of the plurality of electrodes, the lower electrode, and the upper electrode may be the same or different from each other, for example, the lower electrode Au and the upper electrode Pt.

The present invention also provides a method of fabricating a resistive memory device comprising forming a bismuth-antimony material of Formula 1 on a substrate.

In the present invention, the method for producing the Bi _{1 - x} Sb _x resistance variable material is not particularly limited, and may be formed through electroplating using, for example, a Bi precursor and a Sb precursor.

It is not particularly limited and is available as the Bi precursor in the present invention, for example, _{Bi (NO 3) 3, Bi} (NO 3) 3 · 5H 2 O, BiNBO 4, Bi 2 VO 5, BiR 1 2 (R 1 ^{_{2 NCH 2 R 2), BiBr}} 3, BiCl 3, BiF 3, Bi 2 (Al 2 O 4) 3 · xH 2 O, Bi (OCOC (CH 3) 2 (CH 2) 5 CH 3) 3, Bi ( _{O) NO 3, Bi 5 O} (OH) 9 (NO 3) 4, (CH 3 CO 2) 3 Bi, (BiO) 2 CO 3, [O 2 CCH 2 C (OH) (CO 2) CH 2 CO _{2] Bi, C 7 H 5} BiO 6 · xH 2 O, BiI 3, Bi 2 (MoO 4) 3, selected from the group consisting of _{Bi 2 O 3, BiClO, BiIO} , BiO 4 P, HOC 6 H 4 COOBiO May be used. Here, x may be 1 to 20, and R ¹ and R ² may each independently be an alkyl group, an alkylene group, an aryl group, or an arylene group having 1 to 20 carbon atoms.

In the present invention, the Sb precursor is not particularly limited and includes, for example, SbCl ₃ , SbCl ₅ , Sb (NO ₃ ) ₃ , _{Sb (NO 3) 3 · 5H} 2 O, SbBr 3, SbF 3, Sb 2 (Al 2 O 4) 3 · xH 2 O, Sb (OCOC (CH 3) 2 (CH 2) 5 CH 3) 3, Sb _{(O) NO 3, Sb 5} O (OH) 9 (NO 3) 4, (CH 3 CO 2) 3 Sb, (SbO) 2 CO 3, [O 2 CCH 2 C (OH) (CO 2) CH 2 CO ₂ Sb, C ₇ H ₅ SbO ₆ .xH ₂ O, SbI ₃ , SbI ₄ , Sb ₂ (MoO ₄ ) ₃ , Sb ₂ O ₃ , SbClO, SbIO, SbO ₄ P, HOC ₆ H ₄ COOSb, Sb (R ³ ) ₃ , and Sb [N (R ⁴ ) ₂ ] ₃ may be used. Here, x may be 1 to 20, and R ³ and R ⁴ may each independently be an alkyl group, an alkylene group, an aryl group, or an arylene group having 1 to 20 carbon atoms.

In the present invention, the Bi _{1 - x} Sb _x resistance variable material may be formed in a nanowire form using porous aluminum oxide formed through anodic oxidation as a mold.

The present invention provides a Bi _{1 - x} Sb _x resistive memory device that is not a metal oxide and does not require a forming process. Bi ₁ in the AAO (Anodic Aluminum Oxide) through the previous studies _- the _x Sb _x nanowires was confirmed that the a device manufactured by growing the electroplating method shows a bipolar (bipolar) resistance memory device characteristics.

The present invention proposes a Bi _{1 - x} Sb _x resistance memory device. Bi _{1 - x} Sb _x has been studied extensively as a typical thermoelectric material and has different electrical characteristics depending on x value. 0.05 <x <0.22 shows a semiconducting characteristic and x> 0.22 shows a semimetallic characteristic. For thermoelectric elements, materials having a composition of x < 0.22 showing mainly semiconductor characteristics have been mainly studied, and hysteresis such as a resistance change memory has not appeared at all.

However, in the present invention, Bi _{1 - x} Sb _x exhibiting a half-metal characteristic of x> 0.22 exhibits a resistance change memory characteristic, so that it can respond to a resistance memory device. Unlike a metal oxide device whose initial state is in an insulated state, Bi _{1 - x} Sb _x can be switched without a forming process requiring a high voltage application since the initial state is an on state with a small resistance.

Hereinafter, the present invention will be described in more detail with reference to examples and test examples. The following Examples and Test Examples are given to illustrate the constitution and effects of the present invention specifically, and the scope of the present invention is not limited by the following Examples and Test Examples.

[Example 1]

In this embodiment, a single nanowire device was fabricated. The x value of Bi _{1 - x} Sb _x was about 0.25. Specifically, in the manufacturing process of FIG. 1, an anodized aluminum oxide (AAO) template and an electroplating method are used to form Bi _{1 - x} Sb _x I made a nanowire.

In order to pretreat the surface of the high-purity aluminum plate, a DC voltage of about 10 V was applied while the aluminum plate was dipped in a solution of perchloric acid (HClO ₄ ) and ethanol (C ₂ H ₅ OH) in a volume ratio of 1: 4 . At this time, more current was concentrated on the protruding portion of the surface, and the surface was smoothly polished. Thereafter, polishing was performed to even out the aluminum surface.

The polished aluminum plate was immersed in an aqueous solution of an electrolyte for anodic oxidation (C ₂ H ₂ O _{4 ,} 0.3 M), and a voltage of 40 V was applied thereto to carry out one-step anodic oxidation.

The AAO formed by the first step anodization was immersed in a mixture of 1.8 wt% chromic acid (H ₂ CrO ₄ ) and 6 wt% phosphoric acid (H ₃ PO ₄ ) at 60 ° C for 6 hours.

Two - step anodic oxidation was performed similar to the one - step anodic oxidation.

The formed AAO template was separated from aluminum by applying a voltage of 45 V in a solution of perchloric acid (HClO ₄ ) and ethanol (C ₂ H ₅ OH) in a volume ratio of 1: 1.

A gold (Au) thin film was deposited on one side of the AAO template to 2000 ANGSTROM to make the conductive thin film necessary for electroplating.

AAO was immersed in an electrolyte containing 0.15 M Bi (NO ₃ ) ₃ .5H ₂ O and 0.05 M SbCl ₃ in dimethylsulfoxide (DMSO), and a voltage of -0.08 V was applied to the electrode to remove Bi _{1 - x} Sb _x nanowires Electroplating method.

The AAO template was immersed in a solution of perchloric acid (HClO ₄ ) and ethanol (C ₂ H ₅ OH) in a volume ratio of 1: 1 to completely remove AAO to obtain a Bi _{1 - x} Sb _x nanowire as shown in FIG.

A single nanowire device was fabricated by patterning platinum electrodes on a prepared SiO ₂ / Si substrate using electron beam lithography and lift-off methods on a single nanowire.

[Test Example 1]

2 is an electron micrograph of a Bi _{1 - x} Sb _x nanowire (left) and a fabricated single nanowire device (right) manufactured according to one embodiment of the present invention.

FIG. 3 is a graph showing transmission electron microscopy (TEM) analysis (left), X-ray spectroscopy (left inside), scanning transmission electron microscope (STEM) data of Bi _{1 - x} Sb _x nanowires prepared according to an embodiment of the present invention (Right).

FIG. 3 shows X-ray diffraction measurement results of Bi _{1 - x} Sb _x nanowires fabricated according to Example 1. According to an X-ray diffraction pattern of Bi _{1 - x} Sb _x nanowires, (012) And a polycrystalline structure in which a main peak in the direction and a peak in the other direction are present. Also, the microstructure was observed using a transmission electron microscope. The crystal structure was observed as shown in the left side of FIG. 3, and the diffraction pattern (left inset in FIG. 3) coincided with the X-ray rotation measurement result.

4 is an IV characteristic curve of a single nanowire device fabricated according to an embodiment of the present invention. According to the IV characteristic curve of the single nanowire device shown in FIG. 4, when the voltage is swept to a negative voltage, the initial state is an on state having a small resistance value, unlike the other metal oxides, At 0.8 V, the resistance value was switched to the off state. Then, when the voltage was swept to a positive voltage, it was initially turned off and then switched to an on state at around 0.6V. Since the direction of the voltage must be changed for on / off switching, the Bi _{1 - x} Sb _x device exhibits a bipolar characteristic.

[Example 2]

In this embodiment, a nanowire array element was fabricated. The x value of Bi _{1 - x} Sb _x was about 0.25. Specifically, as shown in FIG. 5, a nanowire array device was fabricated using the AAO template as follows.

First, a metal electrode, such as Au or Pt, and Al of about 1 탆 thickness are deposited on the silicon substrate as a bottom electrode.

(C ₂ H ₂ O _{4 ,} 0.3 M) was used as an electrolyte for anodizing in this embodiment. The temperature was maintained at 15 ° C., and a voltage of 40 V The After the anodic oxidation was performed for 3 minutes, the formed AAO layer was melted in a mixed solution of 1.8 wt% chromic acid (H ₂ CrO ₄ ) and 6 wt% phosphoric acid (H ₃ PO ₄ ) at 60 ° C. for 10 minutes, Thereby forming a porous AAO layer.

Next, passivation is performed using polymethylmethacrylate (PMMA) to expose only the AAO portion to be electroplated to the electrolyte solution by using a resist, and then an e-beam lithography Respectively.

In order to electro-deposit the Bi _{1 - x} Sb _x nanowires, the selectively exposed AAO was doped with 0.15 M Bi (NO ₃ ) ₃ .5H ₂ O and 0.05 M SbCl in DMSO (Fisher, 99.9% ₃ (both Sigma Chemicals 99.97%) was immersed in the electrolyte and the voltage of -0.08 V was applied to the electrode. In the present embodiment, a three-electrode electrolytic plating method was used.

Optionally, the AAO template was evenly plated with nanowires and then the PMMA used as passivation was removed with acetone.

The nanowire was spin coated with PMMA on the electrolytically plated AAO template, and the top electrode was patterned using e-beam lithography. Pt with a thickness of about 100 nm was deposited by sputtering and a nanowire array device was fabricated using a lift-off method.

[Test Example 2]

FIG. 6 is an electron micrograph of the top (left) and side (right) sides of the nanowire array of the nanowire array device fabricated according to another embodiment of the present invention. Electron microscope photographs showing that the nanowires were electrolytically plated on the sides.

7 is a graph showing resistance change characteristics of a highly integrated nanowire element fabricated according to another embodiment of the present invention. According to the IV characteristic curve of the nanowire array element of FIG. 7, similar to a single nanowire element, Was on, and showed bipolar switching characteristics.

Claims (14)

A resistive memory element comprising a bismuth-antimony material of the formula (1)
[Chemical Formula 1]
Bi _{1 - x} Sb _x
Where x is 0.22 to 0.3.
The method according to claim 1,
Wherein the resistance memory element has a bipolar switching characteristic.
The method according to claim 1,
Wherein the bismuth-antimony material has a nanowire or thin film form.
The method of claim 3,
Wherein the nanowire has a diameter of 10 to 200 nm.
The method according to claim 1,
Board;
A bismuth-antimony material formed on the substrate; And
And a plurality of electrodes formed on the substrate and connecting the bismuth-antimony material.
The method according to claim 1,
Board;
A lower electrode formed on the substrate;
A bismuth-antimony material formed on the lower electrode; And
And an upper electrode formed on the bismuth-antimony material.
The method according to claim 5 or 6,
The bismuth-antimony material may be composed of a single nanowire,
And a nanowire array including a plurality of nanowires.
The method according to claim 5 or 6,
Wherein the substrate is a silicon, polyimide film, or polyester film.
The method according to claim 5 or 6,
Wherein each of the electrodes is independently at least one selected from the group consisting of Au, Pt, and Ti.
Forming a bismuth-antimony material of the following formula (1) on a substrate:
[Chemical Formula 1]
Bi _{1 - x} Sb _x
Where x is 0.22 to 0.3.
11. The method of claim 10,
Wherein the bismuth-antimony material is formed through electroplating using a bismuth precursor and an antimony precursor.
12. The method of claim 11,
The bismuth precursor may be selected from the group consisting of Bi (NO ₃ ) ₃ , Bi (NO ₃ ) ₃ .5H ₂ O, BiNBO ₄ , Bi ₂ VO ₅ , BiR ¹ ₂ (R ¹ ₂ NCH ₂ R ² ), BiBr ₃ , BiCl ₃ , BiF _{3, Bi 2 (Al 2 O} 4) 3 · xH 2 O, Bi (OCOC (CH 3) 2 (CH 2) 5 CH 3) 3, Bi (O) NO 3, Bi 5 O (OH) 9 (NO ₃ ) ₄ , (CH ₃ CO ₂ ) ₃ Bi, (BiO) ₂ CO ₃ , [O ₂ CCH ₂ C (OH) (CO ₂ ) CH ₂ CO ₂ ] Bi, C ₇ H ₅ BiO ₆ .xH ₂ O , and _{BiI 3, Bi 2 (MoO 4} ) 3, at least one element selected from the group consisting of Bi ₂ O _3, BiClO, BiIO, BiO ₄ P, HOC ₆ H ₄ COOBiO, wherein x is 1 to 20, R ¹ and R ² are each independently an alkyl group, an alkylene group, an aryl group or an arylene group having 1 to 20 carbon atoms.
12. The method of claim 11,
The antimony precursor may be SbCl ₃ , SbCl ₅ , Sb (NO ₃ ) ₃ , _{Sb (NO 3) 3 · 5H} 2 O, SbBr 3, SbF 3, Sb 2 (Al 2 O 4) 3 · xH 2 O, Sb (OCOC (CH 3) 2 (CH 2) 5 CH 3) 3, Sb _{(O) NO 3, Sb 5} O (OH) 9 (NO 3) 4, (CH 3 CO 2) 3 Sb, (SbO) 2 CO 3, [O 2 CCH 2 C (OH) (CO 2) CH 2 CO ₂ Sb, C ₇ H ₅ SbO ₆ .xH ₂ O, SbI ₃ , SbI ₄ , Sb ₂ (MoO ₄ ) ₃ , Sb ₂ O ₃ , SbClO, SbIO, SbO ₄ P, HOC ₆ H ₄ COOSb, Sb (R ³ ) ₃ , and Sb [N (R ⁴ ) ₂ ] ₃ , wherein x is 1 to 20, R ³ and R ⁴ are each independently selected from the group consisting of An alkyl group, an alkylene group, an aryl group, or an arylene group.
12. The method of claim 11,
Wherein the bismuth-antimony material is formed in a nanowire shape using a porous aluminum oxide formed through anodization as a mold.

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