WO2014094334A1

WO2014094334A1 - Memristor based on aginsbte chalcogenide compounds, and preparation method therefor

Info

Publication number: WO2014094334A1
Application number: PCT/CN2012/087714
Authority: WO
Inventors: 缪向水; 张金箭; 孙华军; 王青; 徐小华
Original assignee: 华中科技大学
Priority date: 2012-12-20
Filing date: 2012-12-27
Publication date: 2014-06-26
Also published as: CN103050622B; CN103050622A

Abstract

Provided is a memristor based on AgInSbTe chalcogenide compounds. The memristor includes an upper electrode layer (103), a lower electrode layer (101) and a functional material layer (102) located between the upper and lower electrode layers (103, 101), wherein the functional material layer (102) is prepared from chalcogenide alloy compounds with molecular formulae such as Ag₅In₅Sb₆₀Te₃₀, Ag_5.5In_6.5Sb₅₉Te₂₉, Ag₇In₃Sb₆₀Te₃₀, Ag₃In₄Sb₇₆Te₁₇, Ag_12.4In_3.8Sb_55.2Te_28.6, Ag_3.4In_3.7Sb_76.4Te_16.5, AgSbTe₂ and AgInTe. Also provided is a corresponding preparation method. By means of the preparation method, a memristor component can be prepared in a mode which is low cost and convenient to control; and the prepared product can provide a non-volatile intermediate resistance state, and the multi-stage continuous adjustability of a resistor can be realized.

Description

Memristor based on AglnSbTe sulfur compound and preparation thereof

[Technical Field]

The invention belongs to the technical field of microelectronic materials and devices, and more particularly to a memristor based on an AglnSbTe sulfur compound and a preparation method thereof.

【Background technique】

In 1971, Professor Cao Shaoqi of the University of California at Berkeley first predicted the fourth passive circuit component f-resistor in addition to resistance, capacitance, and inductance. Its basic feature is the ability to remember the charge flowing through and react with changes in electrical resistance. Due to its small size, low power consumption, fast speed, and non-volatility, the memristor has become an important candidate for next-generation nonvolatile memory. In addition, the circuit characteristics of the memristor enable it to achieve the fusion of storage and operation, thus breaking through the traditional von Neumann structural bottleneck and constructing a new computer structure; its nonlinear resistive behavior makes it in multi-value storage, Potential applications in oscillators, chaotic circuits, and signal processing; and because their charge-memory properties are very similar to those of biological neuron synapses, memristors are also thought to mimic neurons, achieve cognitive storage, and A great device for artificial intelligence.

In 2008, HP Labs pioneered the Ti0 ₂ based memristor prototype device, and used a two-layer Ti0 ₂ layer as a functional material. One layer of Ti0 ₂ has oxygen vacancies, and the other layer of Ti0 ₂ has a natural state without oxygen vacancies. . Since then, researchers have conducted extensive research on memristors, and functional materials as an important part of memristors have received great attention. E.g,

CN102738387A discloses a memristor based on TiOx structure and a preparation method thereof, wherein the method of surface thermal oxidation after primary sputtering of a Ti layer replaces the original two-layer structure ALD process, thereby reducing the preparation cost; CN101864592A discloses A memristor based on a ferroelectric metal heterojunction and a preparation method thereof, wherein a micro memristor unit is constructed in this manner by sandwiching a memristor ferroelectric potassium niobate film between two metal electrode films.

However, the study found that the memristor and its preparation process in the prior art still exist. The following deficiencies: First, since the commonly used memristor functional materials are composed of oxides, it is usually necessary to use a heterostructure of a multilayer oxide, which requires a more complicated process to control between the functional layers. The material composition correspondingly increases the difficulty in the preparation process; secondly, although the prior art oxide memristor has better resistive storage characteristics, the gradual change characteristic of the resistor is difficult to control; The preparation method in the art requires a large initializing electrical operation before exhibiting memristive properties, which is very disadvantageous for industrial mass production processes. [Summary of the Invention]

In view of the above defects and/or technical requirements of the prior art, an object of the present invention is to provide a memristor based on AglnSbTe sulfur compound and a preparation method thereof, which are selected by a functional material of a memristor and a preparation process thereof. The improved, correspondingly low-cost, easy-to-manage, no need for large initial electrical operation to prepare memristor components, the resulting product not only provides a non-volatile intermediate resistance state, but also achieves resistance The multi-stage is continuously adjustable, and no phase change occurs during the implementation, which is significantly different from the phase change memory in the prior art.

According to an aspect of the invention, there is provided a mesorereceptor based on an AglnSbTe chalcogenide compound, the memristor comprising an upper electrode layer, a lower electrode layer and a functional material layer between the upper and lower electrode layers, wherein: The functional material layer is made of an AglnSbTe chalcogenide alloy compound.

Further preferably, the AglnSbTe sulfur-based alloy compound is any one or a combination of alloy compounds having the following molecular formula: Ag ₅ In ₅ Sb ₆ . Te ₃ . , Ag ₅ . ₅ In _6. ₅ Sb ₅₉ Te ₂₉ , Ag ₇ In ₃ Sb ₆₀ Te ₃₀ , Ag ₃ In ₄ Sb ₇₆ Te ₁₇ , Ag ₁₂ . ₄ In ₃ . ₈ Sb ₅₅ . ₂ Te ₂₈ . ₆ , Ag ₃ . ₄ In ₃ . ₇ Sb ₇₆ . ₄ Te ₁₆ . ₅ , AgSbTe ₂ and AgInTe.

According to the above concept, since the AgnSbTe sulfur-based alloy compound is used to form the functional material layer of the memristor, a large number of intrinsic defects of the sulfur-based alloy compound itself can be fully utilized, thereby facilitating the generation of mechanisms such as space charge limiting current. It also facilitates the migration of conductive Ag ions; in addition, by studying the molecular structure of the sulfur-based alloy compound, tests have shown that the sulfur-based compound having the above molecular formula has excellent memristive properties and can achieve precise and controllable resistance gradient Performance is therefore especially suitable for the manufacturing use of memristors. Further preferably, the functional material layer has a thickness of 5 nm to 600 calendars. By limiting the thickness of the memristor functional material to the above nanometer scale, on the one hand, it is based on deposition processing and manufacturing cost considerations. On the other hand, more comparative tests show that the above thickness range can facilitate the realization of the memory Precise control of the memristive characteristics of the resistor.

Further preferably, the upper and lower electrode layers are made of one of Ag, Cu, Al, Pt, Ta, Au, Ti, Ti ₃ W ₇ , W, Cr, ITO, TiN, TaN, IZO or A variety of compositions, and a thickness of 10 nm to 800 nm.

It is found that when the thickness of the electrode layer is too thin, the processing difficulty of the film deposition is increased, and the electrical transport of the device is not favorable. When the electrode layer is too thick, the device structure is inconvenient. Therefore, when the AglnSbTe sulfur-based alloy compound is used as a functional material layer in combination with the electrode layer of the above material, it is necessary to appropriately select the thickness thereof, which is convenient for ensuring the overall performance of the memristor device and facilitating the manufacture in mass production. machining.

Further preferably, the memristor further has a substrate, and the upper electrode layer, the functional material layer and the lower electrode layer collectively constitute a sandwich structure and are disposed over the substrate.

Further preferably, a cross-shaped structure is formed between the upper electrode layer, the functional material layer, and the lower electrode layer.

According to another aspect of the present invention, there is also provided a corresponding preparation method, the method comprising the steps of:

(a) forming a lower electrode pattern on a Si or SiO ₂ substrate by photolithography, etching or nanoimprinting, and forming a lower electrode layer by a thin film deposition method;

(b) depositing a functional material composed of an AglnSbTe chalcogenide alloy on the lower electrode layer formed by the step (a), and forming a functional material layer of the functional material as a storage medium by a lift-off process;

(c) forming a top electrode pattern by photolithography, etching or nanoimprinting on the functional material layer obtained by the step (b), and then forming an upper electrode layer by a thin film deposition method, thereby obtaining a corresponding memory Resistor device products. Further preferably, the thin film deposition method includes a magnetron sputtering method, a chemical vapor deposition method, an electron beam evaporation method, an atomic layer deposition method, or a laser assisted deposition method.

Further preferably, the upper electrode layer, the functional material layer, and the lower electrode layer are formed as a cross structure perpendicular to each other.

In general, the memristor according to the present invention and its preparation method have the following technical advantages as compared with the prior art:

1. Since the AglnSbTe sulfur-based alloy compound having a specific molecular structure is used to constitute a functional material layer of the memristor, a large number of intrinsic defects of the sulfur-based alloy compound itself can be fully utilized, and the memristor device obtained is not only provided Excellent memristive characteristics, and can realize multi-level continuous adjustment of resistance under the action of electric pulse;

2. The functional material used in the memristor according to the present invention is a homogenous material, so that surface thermal oxidation, annealing, and the like are no longer required in the preparation process, and the operating voltage can be obtained in a low-cost, easy-to-maneuver manner. Low and compatible memristor device;

3. The memristor fabrication method according to the present invention can obtain memristive characteristics without performing large electrical operations, thereby reducing the difficulty of production process control, and is particularly suitable for large-scale industrial mass production applications.

[Description of the Drawings]

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view showing the overall structure of a memristor based on an AglnSbTe chalcogenide alloy compound according to the present invention;

2 is a schematic diagram showing a current-voltage characteristic curve obtained by performing a test on a memristor device manufactured according to an embodiment of the present invention;

3 is a graph showing changes in resistance of a memristor device produced according to an embodiment of the present invention under positive pulses of different amplitudes;

4 is a graph showing changes in resistance of a memristor device produced according to an embodiment of the present invention under a forward pulse of different pulse widths;

Figure 5 is a negative pulse of a memristor device produced at different amplitudes in accordance with an embodiment of the present invention. Resistance change diagram under action;

Figure 6 is a graph showing the change in resistance of a memristor device fabricated in accordance with an embodiment of the present invention under negative pulse widths of different pulse widths.

Throughout the drawings, the same reference numerals are used to refer to the same elements or structures, in which: 100 - substrate 100 101 - lower electrode layer 101 102 - functional material layer 102 103 - upper electrode layer

[specifically fresh]

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view showing the overall structure of a memristor based on an AglnSbTe chalcogenide alloy compound according to the present invention. As shown in Fig. 1, a memristor constructed in accordance with the present invention mainly includes a substrate 100, a lower electrode layer 101, a functional material layer 102, and an upper electrode layer 103. The lower electrode layer 101, the functional material layer 102, and the upper electrode layer 103 may be formed as a three-layered structure, that is, a so-called sandwich structure, but is not limited to this structure, and is applicable to various units of a memristor. The structure can be used. In fact, a memristor unit can be constructed as long as it has two electrodes and fills the functional material between the electrodes. In different configurations, the electrode structure and dimensions may be the same or different, and the geometry and size of the intermediate functional material layers may also vary. The memristor unit can be fabricated separately or integrated with an MOS, a triode, a diode, etc. to form an array or chip.

The substrate 100 is composed of, for example, Si or SiO ₂ and serves as a supporting base for the entire memristor element. The lower electrode layer 101 and the upper electrode layer 103 are, for example, one or more of Ag, Cu, Al, Pt, Ta, Au, Ti, Ti ₃ W ₇ , W, Cr, ITO, TiN, TaN, IZO. The constituent materials may be the same or different, and respectively form electrical contact with the functional material layer 102 in between. As one of the key improvements of the present invention, the functional material layer 102 is composed of an AglnSbTe chalcogenide compound which can be formed by combining _§ 81^3⁄4 ₂ and InSb or AglnTe and Sb. Specifically, the above AglnSbTe sulfur-based alloy compound has the following molecular structure Any one or combination of alloy compounds: Ag ₅ In ₅ Sb ₆ . Te ₃ . , Ag ₅ . ₅ In _6. ₅ Sb ₅₉ Te ₂₉ , Ag ₇ In ₃ Sb ₆₀ Te ₃₀ , Ag ₃ In ₄ Sb ₇₆ Te ₁₇ , Ag ₁₂ . ₄ In ₃ . ₈ Sb ₅₅ . ₂ Te ₂₈ . ₆ , Ag ₃ . ₄ In ₃ . ₇ Sb ₇₆ . ₄ Te ₁₆ . ₅ , 8 _§ 81^3⁄4 ₂ and AgInTe. Since these sulfur-based compounds are homogenous materials, processes such as thermal oxidation and annealing are not required in the preparation process. Accordingly, the memristor based on the AglnSbTe sulfur-based alloy compound has the characteristics of low operating voltage, low cost, and the like, and is particularly suitable for mass-scale industrial scale production. In addition, under different pulse excitations, this memristor based on AglnSbTe chalcogenide alloy compound can not only provide non-volatile intermediate resistance state, but also realize multi-level continuous adjustment of resistance.

In a preferred embodiment, the thickness of the functional material layer is 5ηπ! 〜600 nm, the thickness of the upper and lower electrode layers is from 10 nm to 800. In another preferred embodiment, the upper electrode layer, the functional material layer and the lower electrode layer may be arranged in parallel along the horizontal direction and completely overlap each other (horizontal structure) or parallel to the horizontal direction. The functional material layer and the upper electrode layer are disposed only to overlap with the lower electrode layer portion (through-hole structure) or a cross-shaped structure perpendicular to each other. Specifically, for the cross-shaped structure, for example, the materials constituting the lower electrode layer are laterally arranged in the horizontal direction, and the materials constituting the upper electrode layer are longitudinally arranged in the horizontal direction, and the functional material layer between the two electrode layers is along Arranged in the vertical direction and perpendicular to the upper and lower electrode layers respectively; the structure can bring about the advantages of simple process and high integration.

The preparation process of the memristor based on the AglnSbTe chalcogenide alloy compound according to the present invention will be specifically described below.

First, a lower electrode pattern is formed on a layered substrate made of a material such as Si or SiO ₂ by a pattern transfer technique such as photolithography, etching, nanoimprinting, or other suitable method, followed by magnetron sputtering, chemistry A thin film deposition method such as a vapor deposition method, an electron beam evaporation method, an atomic layer deposition method, or a laser assisted deposition method forms a corresponding upper electrode layer.

Next, a functional material composed of an AgInSbTe sulfur-based alloy compound which is an alloy compound of the following molecular formula or a combination thereof is deposited on the formed lower electrode layer: Ag ₅ In ₅ Sb ₆ . Te ₃ . , Ag _5. ₅ In _6. ₅ Sb ₅₉ Te ₂₉ , Ag ₇ In ₃ Sb ₆ . Te ₃₀ , Ag ₃ In ₄ Sb ₇₆ Te ₁₇ , Ag ₁₂ . ₄ In ₃ . ₈ Sb ₅₅ . ₂ Te ₂₈ . ₆ , Ag ₃ . ₄ In ₃ . ₇ Sb ₇₆ . ₄ Te ₁₆ . ₅ , AgSbTe ₂ and AglnTe, then The functional material is used as a functional material layer of the storage medium by a lift-off process.

Finally, the upper electrode pattern is again formed by photolithography, etching or nanoimprinting on the prepared functional material layer, and then the upper electrode layer is formed by a thin film deposition method, thereby preparing a desired memristor device product. .

The following is an exemplary embodiment executed in accordance with the above operational flow:

The photoresist AZ5214 is spin-coated on the SiO ₂ substrate, and the lower electrode pattern is obtained by the performance of the reverse resist and the photolithography process; then, the magnetron sputtering method is used to deposit the substrate with the lower electrode pattern. An Ag electrode metal conductive film was formed, and a lower electrode layer having a thickness of 200 nm was formed by a lift-off process.

A photoresist AZ5214 is spin-coated on a substrate with a lower conductive electrode, and a pattern of the functional material layer is obtained by using the performance of the reverse photoresist and a photolithography process; then, magnetron sputtering is performed on the functional material layer pattern. The method comprises depositing an AglnSbTe film, and forming a functional material layer having a thickness of 25 nm by using an AglnSbTe film as a storage medium by a lift-off process;

A photoresist AZ5214 is spin-coated on the functional material layer, and the upper electrode pattern of Ag is obtained by the performance of the reverse photoresist and the photolithography process; then, using a magnetron sputtering method, on the functional material layer with the upper electrode pattern An upper electrode metal conductive film is deposited, and an upper electrode layer having a thickness of 200 nm is formed by a lift-off process.

Next, a series of tests will be performed on the memristor produced in accordance with the above embodiment, and the test structure as shown in Figs. 2 to 6 will be obtained.

2 is a graph showing current-voltage characteristics obtained by performing tests on a memristor device fabricated in accordance with an embodiment of the present invention. The memristor device did not undergo a large initializing electrical operation prior to testing. As shown in Figure 2, the device has a significant memristive characteristic IV curve over a voltage sweep range of -0.4V to 0.4V. In forward scanning, the device remains in a high-impedance state until the voltage is scanned to 0.11V, after which the device resistance continues to decrease. In a negative-scan, the device remains in a low-impedance state until the voltage exceeds -0.23V. -0.23V device resistance rises rapidly, after one Until the voltage sweep returns to zero, the device resistance rises slowly.

Figure 3-6 show the resistance changes of the fabricated memristor device under positive and negative pulses of different pulse widths and different amplitudes. As shown in these figures, the memristive device can achieve a gradual change in resistance over a plurality of pulses when the appropriate pulse amplitude and pulse width are selected. Pulses of different amplitudes or pulse widths have different effects on device resistance. The larger the amplitude or pulse width of the pulse, the greater the rise or fall of the device resistance, and the final resistance value that the device can achieve. As apparent from the above, the memristor according to the present invention has not only memristive characteristics but also resistance gradient characteristics which can be controlled under the action of a pulse.

Those skilled in the art will appreciate that the above description is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and any modifications, equivalent substitutions and improvements made within the spirit and scope of the present invention, All should be included in the scope of protection of the present invention.

Claims

Rights request

1. A memristor based on AglnSbTe sulfide compound. The memristor includes an upper electrode layer, a lower electrode layer and a functional material layer between the upper and lower electrode layers. It is characterized in that: the functional material layer is made of AglnSbTe sulfide. Made of alloy compounds.

2. The memristor according to claim 1, wherein the AglnSbTe sulfur series alloy compound is any one of the alloy compounds with the following molecular formula structure or a combination thereof: Ag ₅ In ₅ Sb ₆₀ Te ₃₀ , Ag ₅₅ In ₆₅ Sb ₅₉ Te ₂₉ , Ag ₇ In ₃ Sb ₆₀ Te ₃₀ , Ag ₃ In ₄ Sb ₇₆ Te ₁₇ _, Ag _12. ₄ In 3. ₈ Sb _55. ₂ Te _28. ₆ , Ag _3. ₄ In ₃ . ₇ Sb _76. ₄ Te _16. ₅ , AgSbTe ₂ and AgInTe.

3. The memristor according to claim 1 or 2, characterized in that the thickness of the functional material layer is 5 Å to 600 Å.

4. The memristor according to claim 3, wherein the upper and lower electrode layers are made of Ag, Cu, Al, Pt, Ta, Au, Ti, Ti ₃ W ₇ , W, Cr, ITO, It is composed of one or more of TiN, TaN, and IZO, and its thickness is 10 nm to 800 nm.

5. The memristor according to any one of claims 1 to 4, characterized in that the memristor also has a substrate, and the upper electrode layer, functional material layer and lower electrode layer together form a sandwich structure, and placed on the substrate.

6. The memristor according to claim 5, wherein the upper electrode layer, the functional material layer and the lower electrode layer form a criss-cross structure.

7. A method for preparing the memristor according to any one of claims 1-7, the method includes the following steps:

(a) Use photolithography, etching or nanoimprint technology to produce a lower electrode pattern on a Si or Si0 ₂ substrate, and form a lower electrode layer through thin film deposition;

(b) depositing a functional material composed of an AglnSbTe chalcogenide alloy compound on the lower electrode layer formed in step (a), and preparing a functional material layer using the functional material as a storage medium through a stripping process; (c) Use photolithography, etching or nanoimprint technology to make an upper electrode pattern on the functional material layer prepared in step (b), and then form the upper electrode layer through thin film deposition, thereby producing the corresponding memory. resistor device products.

8. The method of claim 7, wherein the thin film deposition method includes, for example, magnetron sputtering, chemical vapor deposition, electron beam evaporation, atomic layer deposition or laser-assisted deposition.

9. The method according to claim 7 or 8, wherein the thickness of the upper and lower electrode layers is 10 nm to 800 nm respectively, the thickness of the functional material layer is 5 nm to 600 nm, and the upper electrode The three layers, the functional material layer and the lower electrode layer are formed into a cross structure perpendicular to each other.