Preparation method of memristor and memristor

Abstract

The invention discloses a preparation method of a memristor and the memristor. The preparation method of the memristor comprises the following steps: forming a bottom electrode on a substrate; forming a memristor material layer on one side, far away from the substrate, of the bottom electrode; bombarding the memristive material layer through a helium ion beam to form a conductive channel structure in the memristive material layer; and forming a top electrode on one side, far away from the bottom electrode, of the memristor material layer, wherein the top electrode is electrically connected with the conductive channel structure. According to the technical scheme, the helium ion beam is used for bombarding the memristive material layer to obtain the conductive channel, so that the construction method of the conductive channel is higher in controllability and wider in applicability.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor technology, and in particular, relates to a method for preparing a memristor, and a memristor. Background Art

[0002] As the line width of semiconductor process approaches sub-10nm, the development of Moore's Law is gradually slowing down. In order to improve computer performance, it is necessary to bring the storage module and the computing module closer together until the integration of storage and computing is achieved. The memristor (RRAM) based on the principle of resistance switching is one of the important technical solutions to break through the traditional architecture of separation of storage and computing and achieve storage and computing integration. However, in order to realize the practical application of memristors, memristors need to have appropriate performance parameters such as resistance switching ratio, switching (threshold) voltage, cycle durability, and resistance retention time. Memristors with mismatched parameters are not compatible with CMOS processes. Compared with interface memristors, microwire memristors have a larger resistance switching ratio and switching speed, but there is currently a lack of effective means for controllable construction of conductive channels. Therefore, the development of a conductive channel construction method with strong controllability and wide applicability is of great significance for achieving good regulation of memristor performance and promoting the practical application of memristors. Summary of the invention

[0003] The embodiments of the present application provide a method for preparing a memristor, and a memristor, and provide a method for constructing a conductive channel with strong controllability and wide applicability.

[0004] The present application provides a method for preparing a memristor, comprising:

[0005] A bottom electrode is formed on a substrate; a memristive material layer is formed on a side of the bottom electrode away from the substrate; the memristive material layer is bombarded by a helium ion beam to form a conductive channel structure in the memristive material layer; a top electrode is formed on a side of the memristive material layer away from the bottom electrode, and the top electrode is electrically connected to the conductive channel structure.

[0006] In some embodiments, bombarding the memristive material layer with a helium ion beam includes:

[0007] The memristive material layer is bombarded by a helium ion beam generated by a helium ion microscope.

[0008] In some embodiments, bombarding the memristive material layer with a helium ion beam emitted by a helium ion microscope includes:

[0009] A top electrode pattern is formed on a side of the memristive material layer away from the bottom electrode; in the top electrode pattern, a helium ion beam generated by a helium ion microscope bombards the memristive material layer.

[0010] In some embodiments, forming a top electrode pattern on a side of the memristive material layer away from the bottom electrode includes:

[0011] A photoresist layer is formed on the side of the memristor material layer away from the bottom electrode; and the photoresist layer is patterned to obtain the top electrode pattern.

[0012] In some embodiments, bombarding the memristive material layer with a helium ion beam includes:

[0013] The memristor material layer is subjected to one of point bombardment, line scanning bombardment and surface scanning bombardment by a helium ion beam, wherein the dose range of the point bombardment is 0.01 to 100 pC, the dose range of the line scanning bombardment is 0.01 to 100 nC / μm, and the dose range of the surface scanning bombardment is 0.01 to 100 nC / μm 2 .

[0014] In some embodiments, the cross-sectional shape of the conductive channel structure includes one of a hollow shape, a rectangle, a square, and an inverted cone.

[0015] In some embodiments, a memristive material layer is formed on a side of the bottom electrode away from the substrate, including: forming a memristive material layer on a side of the bottom electrode away from the substrate by at least one method of fixed-point transfer, magnetron sputtering or chemical vapor deposition, and the memristive material layer includes at least one of boron nitride, mica or molybdenum disulfide.

[0016] In some embodiments, forming a top electrode on a side of the memristive material layer away from the bottom electrode includes:

[0017] A top electrode is formed on a side of the memristive material layer away from the bottom electrode by one of thermal evaporation, electron beam evaporation, magnetron sputtering, etc. The material of the top electrode includes at least one of silver, copper, titanium, chromium and indium.

[0018] In some embodiments, material of the top electrode extends into the conductive via structure.

[0019] The preparation method provided in the embodiment of the present application forms a conductive channel structure in the memristor material by bombarding the memristor material layer with a helium ion beam, which can make the construction method of the conductive channel more controllable and more applicable. First, as a precise physical tool, the helium ion beam can bombard the memristor material layer with high precision. This bombardment process can locally change the structure of the material, thereby forming a conductive channel at a specific position. Compared with traditional chemical or thermal treatment methods, helium ion beam bombardment has higher precision and controllability, and can accurately control the position, shape and size of the conductive channel. Secondly, the parameters of the ion beam (such as energy, beam current and bombardment time) can be adjusted according to demand to optimize the formation process of the conductive channel. This makes the manufacture of memristors more flexible and can adapt to different application scenarios and performance requirements.

[0020] The embodiment of the present application also provides a memristor, which is prepared according to the preparation method shown above. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0022] Figure 1 A schematic diagram of the structure of a memristor provided in an embodiment of the present application;

[0023] Figure 2 A schematic diagram of a process for preparing a memristor provided in an embodiment of the present application;

[0024] Figure 3 A schematic diagram of a specific process of a method for preparing a memristor provided in an embodiment of the present application;

[0025] Figures 4 to 10 A diagram of the steps for preparing a memristor provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments provided by the present application, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present application.

[0027] Unless the context requires otherwise, throughout the specification and claims, the term "comprising" is to be construed in an open, inclusive sense, ie, meaning "including, but not limited to."

[0028] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, unless otherwise specified, "plurality" means two or more.

[0029] When describing some embodiments, the term "connection" and its derivative expressions may be used. The term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For example, when describing some embodiments, the term "connection" may be used to indicate that two or more components are in direct physical or electrical contact with each other.

[0030] Additionally, the use of “based on” is meant to be open and inclusive, as a process, step, calculation, or other action “based on” one or more stated conditions or values ​​may, in practice, be based on additional conditions or values ​​beyond those stated.

[0031] It will be understood that when a layer or element is referred to as being on another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may be present between the layer or element and the other layer or substrate.

[0032] Exemplary embodiments are described herein with reference to cross-sectional views that are idealized exemplary drawings. In the drawings, the thickness of layers and the area of ​​regions are exaggerated for clarity. Therefore, variations in shape relative to the drawings due to, for example, manufacturing techniques and / or tolerances are contemplated. Therefore, the exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but include deviations in shape due to, for example, manufacturing. For example, an etched region shown as a rectangle will typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shape of regions of the device, and are not intended to limit the scope of the exemplary embodiments.

[0033] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0034] As the line width of semiconductor process approaches sub-10nm, the development of Moore's Law is gradually slowing down. In order to improve computer performance, it is necessary to bring the storage module and the computing module closer together until the integration of storage and computing is achieved. The memristor (RRAM) based on the principle of resistance switching is one of the important technical solutions to break through the traditional architecture of separation of storage and computing and achieve storage and computing integration. However, in order to realize the practical application of memristors, memristors need to have appropriate performance parameters such as resistance switching ratio, switching (threshold) voltage, cycle durability, and resistance retention time. Memristors with mismatched parameters are not compatible with CMOS processes. Compared with interface memristors, microwire memristors have a larger resistance switching ratio and switching speed, but there is currently a lack of effective means for controllable construction of conductive channels. Therefore, the development of a conductive channel construction method with strong controllability and wide applicability is of great significance for achieving good regulation of memristor performance and promoting the practical application of memristors.

[0035] For the existing methods of constructing memristor conductive channels, the basic situation is that there is no construction method that combines high efficiency, high resolution, and universality. Several prominent problems with existing methods include: (1) How to improve the resolution and construct a conductive channel with a very small diameter to improve the controllability of memristor switches; (2) How to reduce the complexity of the processing process and develop a universal method that can be widely applied to the combination of various memristor materials and electrode materials; (3) How to increase the flexibility of the processing method, process conductive channels with different geometric structures, and regulate the performance of memristors.

[0036] In view of the above problems, the embodiments of the present application provide a method for preparing a memristor and a memristor. The technical solution provided by the embodiments of the present application has advantages in many aspects, which can specifically include the following aspects:

[0037] First, since a helium ion beam is used to bombard the memristive material layer to form a conductive channel, the helium ion beam can bombard the memristive material layer with high precision. This bombardment process can locally change the structure of the material, thereby forming a conductive channel at a specific location. Compared with traditional chemical or thermal treatment methods, helium ion beam bombardment has higher precision and controllability, and can accurately control the position, shape and size of the conductive channel, thereby improving the controllability and universality of the conductive channel processing method;

[0038] Second, the processing resolution of the helium ion microscope itself is in the sub-10nm range, so it can achieve sub-10nm high-resolution conductive channel construction;

[0039] Third, the technical solution provided in the embodiment of the present application does not limit the specific memristor material and electrode material, so the preparation method of the memristor can be extended to a variety of memristor materials and electrode materials;

[0040] Fourth, the technical solution provided in the embodiment of the present application uses a helium ion beam to bombard the memristor material layer, combining the surface, line and point bombardment processing methods, and the surface processing dose range is selected from 0.01 to 100 nC / μm 2 The line processing dose range is selected as 0.01~100nC / μm, and the single point processing dose range is selected as 0.01~100pC, so as to obtain conductive channels with different geometric structures. The processed conductive channel structures include: hole-shaped, square, rectangular, inverted cone, etc., which makes it easy to realize the regulation of memristor performance.

[0041] Figure 1 This is a schematic diagram of the structure of a memristor provided in an embodiment of the present application. Figure 1As shown, the memristor 10 includes a substrate 101, a bottom electrode 102, a memristive material layer 103, a top electrode 104 and a conductive channel structure 105. The bottom electrode 102 is disposed on the substrate 101, the memristive material layer 103 is disposed on a side of the bottom electrode 102 away from the substrate 101, the conductive channel structure 105 is disposed in the memristive material layer 103, and the conductive channel structure 105 in the embodiment of the present application can be obtained by bombarding the memristive material layer 103 with a helium ion beam, wherein the specific geometric structure of the conductive channel can be prepared according to actual needs, the top electrode 104 is disposed on a side of the memristive material layer 103 away from the bottom electrode 102, and the top electrode 104 is electrically connected to the conductive channel structure 105.

[0042] The present application also provides a method for preparing a memristor. The method can be used to prepare the above-mentioned Figure 1 Memristor in the illustrated embodiment. Figure 2 A schematic diagram of a method for preparing a memristor provided in an embodiment of the present application, wherein the specific structure can be referred to Figure 1 ,like Figure 2 As shown, the preparation method comprises the following steps:

[0043] Step 201 : forming a bottom electrode 102 on a substrate 101 .

[0044] In this step, a substrate 101 may be provided first, and then a bottom electrode 102 may be formed on the substrate 101, wherein the substrate material may be a metal such as aluminum, titanium, etc., and then a bottom electrode with a specific line width may be prepared by depositing an inert metal such as Au, Pt, W or Pd.

[0045] Step 202 : forming a memristive material layer 103 on a side of the bottom electrode 102 away from the substrate 101 .

[0046] In an embodiment of the present application, memristive materials such as hexagonal boron nitride, mica, and molybdenum disulfide are stacked on the bottom electrode through a fixed-point transfer device, or the memristive material is deposited on the bottom electrode through a series of methods such as magnetron sputtering and chemical vapor deposition.

[0047] Step 203 : bombarding the memristive material layer 103 with a helium ion beam to form a conductive channel structure 105 in the memristive material layer 103 .

[0048] In the embodiment of the present application, a helium ion microscope is used to bombard the overlapping area of ​​the bottom electrode / memristor material and the top electrode pattern, that is, the area where the top electrode of the device will be deposited in the future, with a surface processing dose range of 0.01 to 100 nC / μm. 2The line processing dose range is selected as 0.01~100nC / μm, and the single point processing dose range is selected as 0.01~100pC. Combining the surface, line and point bombardment processing methods, the designed conductive channel structure is obtained.

[0049] Step 204 : forming a top electrode 104 on a side of the memristive material layer 103 away from the bottom electrode 102 , wherein the top electrode 104 is electrically connected to the conductive channel structure 105 .

[0050] Exemplarily, the top electrode is deposited by thermal evaporation, electron beam evaporation, magnetron sputtering, etc., and the top electrode can be made of active metals such as Ag, Cu, Ti, Cr, In, etc.

[0051] Through the above preparation method provided in the examples of the present application, it is possible to prepare Figure 1 The memristor shown, and because the conductive channel structure 105 formed in the memristive material layer 103 is obtained by bombarding the memristive material layer 103 with a helium ion beam, the construction method of the conductive channel 103 can be more controllable and more widely applicable.

[0052] Figure 3 A specific process flow chart of a method for preparing a memristor provided in an embodiment of the present application, which can be combined with Figure 4-Figure 10 The schematic diagram of the preparation process shown is used to understand the preparation method of the memristor in the embodiment of the present application.

[0053] like Figure 3 As shown, and also refer to Figure 4-Figure 10 The method for preparing a memristor provided in the embodiment of the present application may include the following steps:

[0054] Step S301 : forming a bottom electrode 102 on the substrate 101 .

[0055] like Figure 4 As shown, PMMA photoresist is spin-coated on the substrate 101, patterned by photolithography or electron beam exposure followed by development, and then an inert metal such as Au, Pt, W or Pd is deposited to prepare a bottom electrode 102 with a specific line width. Alternatively, the bottom electrode 102 with a specific line width can be obtained by stripping graphite, spin-coating photoresist, exposing and patterning, and then etching. The line width of the bottom electrode 102 ranges from hundreds of nanometers to tens of micrometers.

[0056] Step S302 : forming a memristive material layer 103 on a side of the bottom electrode 102 away from the substrate 101 .

[0057] like Figure 5As shown, there may be a variety of ways to form the memristor material layer 103 in this step, which are not limited in the embodiments of the present application. For example, it may be performed by at least one of fixed-point transfer, measurement-controlled sputtering, or chemical vapor deposition. The fixed-point transfer method is to stack the memristor material required for preparing the memristor material on the bottom electrode using a fixed-point transfer device, or to deposit the memristor material on the bottom electrode through a series of methods such as magnetron sputtering and chemical vapor deposition. In this way, the memristor material layer 103 can be formed. The memristor material required to form the memristor material layer 103 may include at least one of boron nitride, mica, or molybdenum disulfide.

[0058] Step S303 : forming a photoresist coating on a side of the memristor material layer 103 away from the bottom electrode 101 .

[0059] like Figure 6 As shown, a photoresist PMMA solution is dropped onto a substrate having a bottom electrode 101 and a memristive material layer 103, and is spin-coated at a speed of 500 to 8000 rpm for 0.1 to 3 minutes to obtain a photoresist layer with a thickness of about 0.1 to 10 μm.

[0060] Step S304: forming a top electrode 104 pattern on the photoresist layer.

[0061] like Figure 7 As shown, according to the pattern of the top electrode 104, electron beam or photolithography is used for exposure, followed by development to pattern the photoresist, thereby obtaining a top electrode 104 pattern with a width ranging from hundreds of nanometers to tens of micrometers.

[0062] Step S305 : bombarding the memristive material layer 103 with a helium ion beam to form a conductive channel structure 105 .

[0063] For example, a helium ion microscope is used to bombard the overlapping area of ​​the bottom electrode 102, the memristor material layer 103 and the top electrode 104, that is, the area where the top electrode 104 of the device will be deposited in the future, with a helium ion beam. The surface processing dose range is selected from 0.01 to 100 nC / μm. 2 The line processing dose range is 0.01 to 100 nC / μm, and the single point processing dose range is 0.01 to 100 pC. By combining the surface, line, and point bombardment processing methods, the designed conductive channel structure 105 is obtained. The cross-sectional shape of the conductive channel structure 105 can be one of a hollow, rectangular, square, and inverted cone, for example Figure 8 As shown, the cross-sectional shape of the conductive channel structure 105 is an inverted cone.

[0064] Step S306 : forming a top electrode 104 on a side of the memristive material layer 103 away from the bottom electrode 102 .

[0065] like Fig. 9As shown, there may be a variety of ways to form the top electrode 104 in this step, which are not limited in the embodiments of the present application. For example, the top electrode 104 may be deposited on the side of the memristive material layer 103 away from the bottom electrode 102 by thermal evaporation, electron beam evaporation, magnetron sputtering, etc. The material for forming the top electrode 104 may be selected from active metals such as Ag, Cu, Ti, Cr, In, etc., and the material of the top electrode 104 extends into the conductive channel structure 105.

[0066] Step S307 : dissolving the photoresist on the side of the memristor material layer 103 away from the bottom electrode 102 .

[0067] like Fig.10 As shown, the substrate is placed in acetone at 0-50°C to remove the PMMA photoresist and the metal thereon.

[0068] At this point, the memristor 10 is completed.

[0069] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that a person skilled in the art can think of within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for preparing a memristor, characterized in that: include: forming a bottom electrode on the substrate; forming a memristive material layer on a side of the bottom electrode away from the substrate; bombarding the memristive material layer with a helium ion beam to form a conductive channel structure in the memristive material layer; A top electrode is formed on a side of the memristive material layer away from the bottom electrode, and the top electrode is electrically connected to the conductive channel structure.

2. The method according to claim 1, characterized in that The bombarding the memristive material layer by a helium ion beam comprises: The memristive material layer is bombarded by a helium ion beam emitted by a helium ion microscope.

3. The method according to claim 2, characterized in that The bombarding of the memristive material layer with a helium ion beam generated by a helium ion microscope comprises: forming a top electrode pattern on a side of the memristive material layer away from the bottom electrode; In the top electrode pattern, the memristive material layer is bombarded by a helium ion beam generated by the helium ion microscope.

4. The method according to claim 3, characterized in that The forming of a top electrode pattern on a side of the memristive material layer away from the bottom electrode comprises: forming a photoresist layer on a side of the memristor material layer away from the bottom electrode; The photoresist layer is patterned to obtain the top electrode pattern.

5. The method according to any one of claims 1 to 4, characterized in that: The bombarding the memristive material layer by a helium ion beam comprises: The memristive material layer is subjected to one of point bombardment, line scanning bombardment and surface scanning bombardment by a helium ion beam, wherein the dose range of the point bombardment is 0.01 to 100 pC, the dose range of the line scanning bombardment is 0.01 to 100 nC / μm, and the dose range of the surface scanning bombardment is 0.01 to 100 nC / μm 2 .

6. The method according to any one of claims 1 to 4, characterized in that: The cross-sectional shape of the conductive channel structure includes one of a hollow shape, a rectangle, a square and an inverted cone.

7. The method according to any one of claims 1 to 4, characterized in that: The step of forming a memristive material layer on a side of the bottom electrode away from the substrate comprises: A memristive material layer is formed on a side of the bottom electrode away from the substrate by at least one of fixed-point transfer, magnetron sputtering or chemical vapor deposition, wherein the memristive material of the memristive material layer includes at least one of boron nitride, mica or molybdenum disulfide.

8. The method according to any one of claims 1 to 4, characterized in that: The forming of a top electrode on a side of the memristive material layer away from the bottom electrode comprises: A top electrode is formed on the side of the memristive material layer away from the bottom electrode by one of thermal evaporation, electron beam evaporation, magnetron sputtering and the like, and the material of the top electrode includes at least one of silver, copper, titanium, chromium and indium.

9. The method according to claim 8, characterized in that The material of the top electrode extends into the conductive via structure.

10. A memristor, characterized in that: It is prepared according to the preparation method shown in any one of claims 1-9.

Images