Resistive random access memory and preparation method thereof

Abstract

The preparation method comprises the steps that a substrate is provided, a bottom electrode, a resistance change part and an oxygen storage part are sequentially formed on the substrate, the resistance change part is located on the bottom electrode, the oxygen storage part is located on the resistance change part, and the oxygen storage part is located on the bottom electrode; or the oxygen storage part is positioned on the side surface of the resistance change part and is in electric contact with the resistance change part; and forming a top electrode on the side surface of the oxygen storage part, wherein the top electrode is electrically contacted with the oxygen storage part. The resistive random access memory prepared by the invention is L-shaped, the moving path of the oxygen atoms is farther, and the bent electric field is superposed, so that the oxygen atoms are difficult to enter the top electrode, and the uncontrollability of oxygen atom migration can be reduced. In addition, the height space can be saved for forming the second via hole, the second interconnection metal layer is connected with the top electrode through the second via hole, the problem that the electrical performance is affected when the thickness of the second interconnection metal layer is not uniform can be avoided, and the density of the resistive random access memory is larger with the same area of the substrate.

Description

Technical Field

[0001] This application relates to the field of microfabrication technology, specifically to a resistive switching memory and its fabrication method. Background Technology

[0002] Resistive Random Access Memory (ReRAM) is a type of non-volatile memory that utilizes the variable resistance of materials to store information. Volatile memory has advantages such as low power consumption, high density, fast read and write speed, and good durability.

[0003] There is a ReRAM with a 1T1R structure, where one transistor corresponds to one resistor (R). The R in the ReRAM structure is in the form of film layer stacking, that is, the bottom electrode, resistive switching part, oxygen storage part and top electrode are stacked in sequence. Under the action of vertical electric field, oxygen atoms have a high probability of entering the top electrode, which leads to the uncontrollability of oxygen atom migration in subsequent cycle operation, thus affecting the device performance. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a resistive switching memory and its fabrication method, which can improve the problem that the existing vertical stacking structure of ReRAM is prone to oxygen atoms entering the top electrode and affecting device performance.

[0005] To address the aforementioned technical problems, in a first aspect, embodiments of this application provide a method for fabricating a resistive random access memory (RRAM), comprising: A substrate is provided on which a bottom electrode, a resistive switching portion, and an oxygen storage portion are sequentially formed, wherein the resistive switching portion is located on the bottom electrode, the oxygen storage portion is located on the resistive switching portion, or the oxygen storage portion is located on the side of the resistive switching portion and is in electrical contact with the resistive switching portion; A top electrode is formed on the side of the oxygen storage section, and the top electrode is in electrical contact with the oxygen storage section.

[0006] Optionally, when the oxygen storage portion is located on the resistive switching portion, a bottom electrode, a resistive switching portion, and an oxygen storage portion are sequentially formed on the substrate, specifically including: The bottom electrode and the resistive switching portion are formed on the substrate; An isolation layer is formed on the substrate, the isolation layer simultaneously covering the top surface of the substrate, the side surface of the bottom electrode, the side surface of the resistive switching part, and the top surface of the resistive switching part; The isolation layer is etched using the resistive switching portion as an etch stop layer to form sidewalls on the sides of the bottom electrode and the resistive switching portion; The oxygen storage section is formed on the top surface of the resistive switching section.

[0007] Optionally, the oxygen storage unit also covers the sidewall.

[0008] Optionally, when the oxygen storage portion is located on the resistive switching portion, a bottom electrode, a resistive switching portion, and an oxygen storage portion are sequentially formed on the substrate, specifically including: The bottom electrode, the resistive switching section, and the first sub-oxygen storage section are formed on the substrate; An isolation layer is formed on the substrate, which simultaneously covers the top surface of the substrate, the side surface of the bottom electrode, the side surface of the resistive switching part, the side surface of the first sub-oxygen storage part, and the top surface of the first sub-oxygen storage part. The isolation layer is etched using the first sub-oxygen storage section as the etching stop layer to form sidewalls on the sides of the bottom electrode, the resistive switching section and the first sub-oxygen storage section. A second sub-oxygen storage unit is formed on the top surface of the first sub-oxygen storage unit, wherein the first sub-oxygen storage unit and the second sub-oxygen storage unit constitute the oxygen storage unit.

[0009] Optionally, the bottom electrode, the resistive switching portion, and the first sub-oxygen storage portion are formed on the substrate, specifically including: A first conductive layer, a resistive switching layer, and a first oxygen storage layer are sequentially formed on the substrate; A mask pattern is formed in the first oxygen storage layer, and the first conductive layer, the resistive switching layer and the first oxygen storage layer are etched to obtain the bottom electrode, the resistive switching part and the first sub-oxygen storage part.

[0010] Optionally, before forming the second sub-oxygen storage unit on the top surface of the first sub-oxygen storage unit, the method further includes: A first insulating portion is formed on the substrate, wherein the first insulating portion is flush with the top surface of the first sub-oxygen storage portion; A second sub-oxygen storage unit is formed on the top surface of the first sub-oxygen storage unit, specifically including: A second oxygen storage layer is formed on the top surface of the first insulating part and the first sub-oxygen storage part; A mask pattern is formed on the top surface of the second oxygen storage layer, and the second oxygen storage layer is etched to obtain the second sub-oxygen storage section.

[0011] Optionally, a top electrode is formed on the side of the oxygen storage section, specifically including: A second conductive layer is formed on the entire surface of the substrate; The second conductive layer is planarized using the oxygen storage section as a CMP stop layer to obtain the top electrode.

[0012] Optionally, when the oxygen storage portion is located on the side of the resistive switching portion and is in electrical contact with the resistive switching portion, a bottom electrode, a resistive switching portion, and an oxygen storage portion are sequentially formed on the substrate, specifically including: The bottom electrode is formed on the substrate; A sidewall is formed on the side of the bottom electrode; A first insulating portion is formed on the substrate, wherein the top surface of the first insulating portion is flush with the top surface of the sidewall; The resistive switching section is formed on the top surface of the bottom electrode; The oxygen storage section is formed on the side of the resistive switching section.

[0013] Secondly, this application also provides a resistive switching memory, comprising: Substrate; The bottom electrode is located on the substrate; The resistive switching section is located on the bottom electrode; An oxygen storage section is located on the resistive switching section, or is horizontally adjacent to and electrically contacted with the resistive switching section; The top electrode is horizontally adjacent to and electrically in contact with the oxygen storage section.

[0014] Optionally, the resistive switching memory further includes sidewalls, which are formed on the sides of the bottom electrode and the resistive switching unit when the oxygen storage unit is located on the resistive switching unit.

[0015] Optionally, the oxygen storage unit includes a first sub-oxygen storage unit and a second sub-oxygen storage unit arranged in sequence. The sidewall also covers the side of the first sub-oxygen storage unit; The top electrode is horizontally adjacent to and electrically in contact with the second sub-oxygen storage unit.

[0016] As described above, the ReRAM fabricated in this application has an overall "L" shape for its bottom electrode, resistive switching section, oxygen storage section, and top electrode. The electric field is curved from the bottom electrode to the top electrode, and the oxygen atoms move horizontally in the oxygen storage section. The horizontal dimension is much larger than the thickness dimension, resulting in a longer oxygen atom movement path. The superimposed curved electric field causes oxygen atoms to concentrate more in the oxygen storage section, making it difficult for them to enter the top electrode, thus reducing the uncontrollability of oxygen atom migration. Furthermore, because the oxygen storage section and the top electrode are in horizontal contact, an "L" shape can be used compared to a stacked structure to save approximately 50 nm of height space for forming the upper second via. The second interconnect metal layer is connected to the top electrode through the second via, thus avoiding the problem of uneven thickness of the second interconnect metal layer due to process limitations, which could affect electrical performance. In addition, the resistive switching memory fabricated in this application occupies a smaller area, allowing for a higher density of resistive switching memory on the same substrate area. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a ReRAM based on related technologies; Figure 2a yes Figure 1 Cross-sectional view of ReRAM in its original state; Figure 2b yes Figure 1 Cross-sectional view of ReRAM after loop operation; Figure 3 This is a schematic flowchart of a ReRAM preparation method provided in an embodiment of this application; Figure 4A-4J This is a flowchart of the first method for fabricating resistive random access memory provided in the embodiments of this application; Figure 5A-5I This is a flowchart of a second method for fabricating resistive random access memory provided in an embodiment of this application; Figure 6 This is a schematic diagram of the resistive switching memory prepared by the third preparation method provided in the embodiments of this application.

[0019] The realization of the objectives, functional features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. The accompanying drawings have illustrated specific embodiments of this application, which will be described in more detail below. These drawings and textual descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this application to those skilled in the art through reference to specific embodiments. Detailed Implementation

[0020] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0021] Please see Figure 1 , Figure 1This is a schematic diagram of a ReRAM structure based on related technologies, including a substrate 10a, and a bottom electrode 20a, a resistive switching section 30a, an oxygen storage section 40a, and a top electrode 50a sequentially formed on the substrate (the four functional layers form a ReRAM structure, hereinafter referred to as R). A first interconnect metal layer 11a may be pre-formed in the substrate 10a, and a via 12a connecting the first interconnect metal layer 11a to the bottom electrode 20a. All top electrodes 50a are connected through a second interconnect metal layer 60a.

[0022] Taking TiN as the bottom electrode 20a, HfOx as the resistive switching section 30a, and TaOx as the oxygen storage section 40a as an example, please refer to [link to relevant documentation]. Figure 2a and Figure 2b , Figure 2a yes Figure 1 A cross-sectional view of ReRAM in its original state. Figure 2b yes Figure 1 The cross-sectional image of the ReRAM after cycling shows that, in the original state, there is a nanocrystalline interface layer between TiN / HfOx (the area between the two parallel lines in the image). This is likely because TiOx and Ti ions can absorb oxygen ions from HfOx, leading to the formation of more oxygen vacancies in HfOx. After cycling, due to oxygen ion migration, the thickness of this interface layer decreases from 2 nm to 1.5 nm. This leads to uncontrollable oxygen atom migration in subsequent cycling operations, thus affecting device performance. Furthermore, the large thickness due to the vertical structure of R makes it impossible to reserve space to fabricate vias between the second interconnect metal layer 60a and the top electrode 50a. The thickness of the second interconnect metal layer 60a is easily affected by process fluctuations, impacting electrical performance. Additionally, the thickness T of the dielectric layer between adjacent Rs is also correspondingly large, and the large aspect ratio makes it easy to generate internal voids during filling. Based on these considerations, this application provides a resistive switching memory and its fabrication method.

[0023] Please see Figure 3 , Figure 3 This is a schematic flowchart of a ReRAM fabrication method provided in an embodiment of this application. The fabrication method of the resistive random access memory may include: S110. A substrate is provided, on which a bottom electrode, a resistive switching portion, and an oxygen storage portion are sequentially formed, wherein the resistive switching portion is located on the bottom electrode, the oxygen storage portion is located on the resistive switching portion, or the oxygen storage portion is located on the side of the resistive switching portion and is in electrical contact with the resistive switching portion.

[0024] In one embodiment, please refer to Figure 4AThe substrate 100 can be a single-element semiconductor material substrate (e.g., a silicon substrate, a germanium substrate, etc.), a composite semiconductor material substrate (e.g., a germanium-silicon substrate, etc.), or a silicon-on-insulator (SOI) substrate, a germanium-on-insulator (GOI) substrate, etc. A first interconnect metal layer 11 and a first via 12 leading the first interconnect metal layer 11 to the surface can be pre-formed in the substrate 100. A bottom electrode 20, a resistive switching portion 30, and an oxygen storage portion 40 are sequentially formed on a substrate 100, wherein the resistive switching portion 30 is located on the bottom electrode 20, and the oxygen storage portion 40 is located on the resistive switching portion 30, as shown below. Figure 4I or Figure 5I As shown, or the oxygen storage section 40 is located on the side of the resistive switching section 30 and is in electrical contact with the resistive switching section 30, such as... Figure 6 As shown.

[0025] It should be noted that the three functional layers—bottom electrode 20, resistive switching section 30, and oxygen storage section 40—can be fabricated in stages. For example, the entire film layer can be fabricated first, followed by patterning, and this process can be repeated three times to fabricate the three functional layers separately. Alternatively, two or even all three functional layers can be fabricated together. For instance, the three film layers can be fabricated first, and then etched using the same mask pattern to form the three functional layers. The specific fabrication method is not particularly limited in the embodiments of this application.

[0026] S120. A top electrode is formed on the side of the oxygen storage section, and the top electrode is in electrical contact with the oxygen storage section.

[0027] As an example, by fabricating a full-surface conductive layer and then planarizing it to expose the oxygen storage portion, a top electrode 50 can be formed on the side of the oxygen storage portion 40. The top electrode 50 is in electrical contact with the oxygen storage portion 40, such as... Figure 4I As shown.

[0028] During the forming operation, under the action of an electric field, oxygen atoms in the resistive switching section can be partially ionized to the oxygen storage layer, and oxygen vacancies are formed in the resistive switching section. During the reset operation, oxygen atoms are pushed back from the oxygen storage layer to the resistive switching section and combine with the oxygen vacancies.

[0029] As examples, the material forming the resistive switching section 30 may include transition metal oxides, such as one or more of hafnium alumina (HfAlO), hafnium oxide (HfOx), aluminum oxide (AlOx), and tantalum oxide (TaOx). The material forming the oxygen storage section 40 may include metallic materials, such as one or more of titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), and aluminum (Al). The materials forming the bottom electrode 20 and the top electrode 50 may include one or more of titanium nitride (TiN) and tantalum nitride (TaN).

[0030] In a traditional vertical ReRAM structure, the electric field is vertical from the bottom electrode 20a to the top electrode 50a. Oxygen atoms move along the thickness direction of the oxygen storage section 40a. The strong driving force of the electric field combined with the short movement path makes it relatively easy for oxygen atoms to enter the top electrode 50a. In the ReRAM fabricated in this embodiment, the bottom electrode 20, resistive switching section 30, oxygen storage section 40, and top electrode 50 are generally L-shaped. From the bottom electrode 20 to the top electrode 50, the electric field is curved, and the movement direction of oxygen atoms in the oxygen storage section 40 is horizontal. The horizontal dimension is much larger than the thickness dimension, resulting in a longer movement path for oxygen atoms. The superimposed curved electric field causes oxygen atoms to concentrate more in the oxygen storage section 40, making it difficult for them to enter the top electrode 50, thereby reducing the uncontrollability of oxygen atom migration. Furthermore, since the oxygen storage section 40 and the top electrode 50 are in horizontal contact, an "L"-shaped structure can be used to save approximately 50 nm of height space compared to the stacked structure. This space is used to form the upper second via 82. The second interconnect metal layer 81 is connected to the top electrode 50 through the second via 82, thereby avoiding the problem of uneven thickness of the second interconnect metal layer 81 due to process reasons, which would affect the electrical performance.

[0031] Figure 1 In the structure, the planar dimensions of the vertical structure R are 90*90nm, the spacing between two adjacent Rs is 85nm, and the area of ​​one array unit is [(90+85) / 28] × [(90+85) / 28] = 39F². In the "L"-shaped R of this invention, the planar dimensions of the oxygen storage layer can be 70*70nm, and the dimensions of the top electrode 50 can also be 70*70nm. The area of ​​one array unit is (140÷28) × (140÷28) = 25F². 2 With a smaller area, the resistive switching memory fabricated in this embodiment occupies a smaller area, thus allowing for a higher density of resistive switching memory with the same substrate area 100.

[0032] Please see Figure 4A-4J This is a flowchart of a method for fabricating a first resistive switching memory provided in this application embodiment. In this embodiment, the oxygen storage unit 40 is located on the resistive switching unit 30. The fabrication method includes: S210, The bottom electrode and the resistive switching portion are formed on the substrate.

[0033] As an example, such as Figure 4A As shown, a first conductive layer 200 and a resistive switching layer 300 can be sequentially formed on a substrate 100. Then, a mask pattern 101 is formed on the resistive switching layer 300, and the first conductive layer 200 and the resistive switching layer 300 are etched sequentially. During etching, different etching gases can be used depending on the materials used for the first conductive layer 200 and the resistive switching layer 300. After etching, the mask pattern 101 is removed, and a bottom electrode 20 and a resistive switching portion 30 can be formed on the substrate 100, as shown. Figure 4B As shown.

[0034] S220. An isolation layer is formed on the substrate, the isolation layer simultaneously covering the top surface of the substrate, the side surface of the bottom electrode, the side surface of the resistive switching part, and the top surface of the resistive switching part.

[0035] As an example, such as Figure 4C As shown, an isolation layer 600 is formed on the substrate 100, which simultaneously covers the top surface of the substrate 100, the side surface of the bottom electrode 20, and the top surface of the resistive switching portion 30. Exemplarily, it can be fabricated using an atomic layer deposition process.

[0036] S230. The isolation layer is etched using the resistive switching part as an etch stop layer to form a sidewall on the side of the bottom electrode and the resistive switching part.

[0037] As an example, the isolation layer 600 can be etched with the resistive switching portion 30 as an etch stop layer to form sidewalls 60 on the sides of the bottom electrode 20 and the resistive switching portion 30, such as... Figure 4D As shown, the sidewall 60 provides electrical protection for the bottom electrode 20 and the resistive switching part 30, serving as an insulating barrier. After etching, the top surface of the resistive switching part 30 is exposed.

[0038] S240, The oxygen storage section is formed on the top surface of the resistive switching section.

[0039] As an example, a first insulating layer 700 can be formed first on the top surface of the substrate, such as... Figure 4D As shown, the first insulating layer 700 covers the top surface of the substrate 100 and completely covers the bottom electrode 20, the resistive switching portion 30, and the sidewall 60. For example, the first insulating layer 700 can be fabricated using a chemical vapor deposition process. Then, the first insulating layer 700 is planarized to form the insulating portion 70, while simultaneously exposing the resistive switching portion 30, as shown. Figure 4E As shown. The insulating portion 70 can fill the surface of the substrate 100.

[0040] Then an oxygen storage layer 400 is formed on the entire surface of the substrate, such as Figure 4F As shown, a mask pattern 102 is formed on the oxygen storage layer 400, and then the oxygen storage layer 400 is etched using the mask pattern 102 as a mask. The mask pattern 102 is then removed, thereby forming the oxygen storage portion 40 on the top surface of the resistive switching portion 30. Figure 4G As shown.

[0041] It should be noted that the size of the mask pattern 102 can be set as needed so that the oxygen storage part 40 covers the side wall 60 at the same time, so as to avoid the oxygen storage part 40 being exposed due to insufficient registration accuracy of the resistive switching part 30.

[0042] S250, A top electrode is formed on the side of the oxygen storage section, and the top electrode is in electrical contact with the oxygen storage section.

[0043] As an example, such as Figure 4H A second conductive layer 500 can be formed on the top of the substrate 100. The second conductive layer 500 covers the exposed top surface of the substrate 100 and completely covers the bottom electrode 20, the resistive switching part 30, the sidewall 60 and the oxygen storage part 40.

[0044] Then, the second conductive layer 500 is planarized using the oxygen storage section 40 as a chemical mechanical polishing (CMP) stop layer to obtain the top electrode 50. The top surface of the top electrode 50 is flush with the top surface of the oxygen storage section 40, and the two are in lateral contact.

[0045] Finally, a second interconnect metal layer 81 can be formed above the top electrode 50, such as... Figure 4I As shown, as an example, a second insulating layer 800 can be formed on the top surface of the top electrode 50 and the oxygen storage portion 40. Then, vias are etched on the second insulating layer 800, and a metal layer is deposited on the vias and the top surface of the second insulating layer 800 to form a second via 82 and a second interconnect metal layer 81. The second interconnect metal layer 81 is connected to the top electrode 50 through the second via 82. It can be understood that because the second insulating layer 800 is formed above the top of R, i.e., the bottom surface of the second insulating layer 800 is flush with the top surface of the top electrode 50, the thickness of the second insulating layer 800 can be reduced (corresponding to...). Figure 1 The T in the middle has a much smaller aspect ratio, which can avoid the formation of holes in the second insulating layer 800.

[0046] It should be noted that in other embodiments, such as Figure 4J As shown, after forming the second conductive layer 500, planarization can be omitted, and the second conductive layer 500 can be directly used as the top electrode 50. Then, the second insulating layer 800 is fabricated, and the second via 82 and the second interconnect metal layer 81 are formed. The second via 82 and the oxygen storage portion 40 are offset in a direction perpendicular to the surface of the substrate 100. In this structure, the electric field formed between the bottom electrode 20 and the top electrode 50 is still curved, which not only reduces the fabrication process but also makes the contact area of ​​the entire top electrode 50 larger. However, it is not as good as... Figure 4I It effectively prevents oxygen atoms from migrating to the top electrode 50.

[0047] Please see Figure 5A-5I This is a flowchart illustrating a second method for fabricating a resistive switching memory (RSM) according to an embodiment of this application. In this embodiment, the oxygen storage unit 40 is also located on the resistive switching unit 30. The fabrication method may include: S310, A bottom electrode, a resistive switching section, and a first sub-oxygen storage section are formed on the substrate.

[0048] As an example, such as Figure 5A As shown, a first conductive layer 200, a resistive switching layer 300, and a first oxygen storage layer 410 can be sequentially formed on a substrate 100. Then, a mask pattern 101 is formed on the first oxygen storage layer 410, and the first conductive layer 200, the resistive switching layer 300, and the first oxygen storage layer 410 are etched sequentially. During etching, different etching gases can be used depending on the materials used for the first conductive layer 200, the resistive switching layer 300, and the first oxygen storage layer 410. After etching, the mask pattern 101 is removed, and a bottom electrode 20, a resistive switching portion 30, and a first sub-oxygen storage portion 41 can be formed on the substrate 100, as shown. Figure 5B As shown.

[0049] S320. An isolation layer is formed on the substrate, the isolation layer simultaneously covering the top surface of the substrate, the side surface of the bottom electrode, the side surface of the resistive switching part, the side surface of the first sub-oxygen storage part, and the top surface of the first sub-oxygen storage part.

[0050] As an example, such as Figure 5C As shown, an isolation layer 600 is formed on the substrate 100, and the isolation layer 600 simultaneously covers the top surface of the substrate 100, the side surface of the bottom electrode 20, the side surface of the resistive switching portion 30, the side surface of the first sub-oxygen storage portion 41, and the top surface of the first sub-oxygen storage portion 41. Exemplarily, it can be fabricated using an atomic layer deposition process.

[0051] S330. The isolation layer is etched using the first sub-oxygen storage section as the etching stop layer to form a sidewall on the side of the bottom electrode, the resistive switching section and the first sub-oxygen storage section.

[0052] As an example, the isolation layer 600 can be etched with the first sub-oxygen storage section 41 as the etch stop layer to form sidewalls 60 on the sides of the bottom electrode 20, the resistive switching section 30, and the first sub-oxygen storage section 41, such as... Figure 5D As shown, the sidewall 60 provides electrical protection for the bottom electrode 20 and the resistive switching section 30, serving as an insulating barrier. After etching, the top surface of the first sub-oxygen storage section 41 is exposed.

[0053] S340. A second sub-oxygen storage section is formed on the top surface of the first sub-oxygen storage section, wherein the first sub-oxygen storage section and the second sub-oxygen storage section constitute the oxygen storage section.

[0054] As an example, a first insulating layer 700 can be formed on the top surface of the substrate 100, such as... Figure 5EAs shown, the first insulating layer 700 covers the top surface of the substrate 100 and completely covers the bottom electrode 20, the resistive switching portion 30, the first sub-oxygen storage portion 41, and the sidewall 60. For example, the first insulating layer 700 can be fabricated using a chemical vapor deposition process. Then, the first insulating layer 700 is planarized to form the insulating portion 70, simultaneously exposing the first sub-oxygen storage portion 41. That is, the first insulating portion 70 is flush with the top surface of the first sub-oxygen storage portion 41. Figure 5F As shown. The insulating portion 70 can fill the surface of the substrate 100.

[0055] Please continue reading. Figure 5F Then, a second oxygen storage layer 420 is formed on the top surface of the first insulating portion 70 and the first sub-oxygen storage portion 41. The material and forming process of the second oxygen storage layer 420 can be the same as those of the first oxygen storage layer 410.

[0056] Please continue reading. Figure 5F A mask pattern 102 is formed on the top surface of the second oxygen storage layer 420, and the second oxygen storage layer 420 is etched to obtain the second sub-oxygen storage section 42, as shown below. Figure 5G As shown. The first sub-oxygen storage unit 41 and the second sub-oxygen storage unit 42 constitute the oxygen storage unit 40.

[0057] In one embodiment, the second sub-oxygen storage unit 42 at least covers the first sub-oxygen storage unit 41 and the sidewall 60. It can tolerate the second sub-oxygen storage unit 42 being slightly off-center, yet still completely covering the first sub-oxygen storage unit 41, so that the dimensions of the first sub-oxygen storage unit 41 in the horizontal direction can be utilized, and the theoretical design values ​​of the oxygen storage unit 40 can be met as much as possible.

[0058] S350, a top electrode is formed on the side of the second sub-oxygen storage unit, and the top electrode is in electrical contact with the second sub-oxygen storage unit.

[0059] As an example, such as Figure 5H A second conductive layer 500 can be formed on the top of the substrate 100. The second conductive layer 500 covers the exposed top surface of the substrate 100 and completely covers the bottom electrode 20, the resistive switching part 30, the sidewall 60 and the oxygen storage part 40.

[0060] Then, using the second sub-oxygen storage section 42 as a CMP stop layer, the second conductive layer 500 is planarized to obtain the top electrode 50, as follows: Figure 5I As shown. The top surface of the top electrode 50 is flush with the top surface of the second sub-oxygen storage section 42, and the two are in side contact. Finally, a second interconnect metal layer 81 and a second via 82 can be formed above the top electrode 50, as described above, and will not be repeated in this embodiment.

[0061] In this embodiment, the oxygen storage section 40 includes a first sub-oxygen storage section 41 and a second sub-oxygen storage section 42, which are fabricated in two stages. First, the first sub-oxygen storage section 41 is formed. Since the first sub-oxygen storage section 41, the resistive switching section 30, and the bottom electrode 20 are etched using the same mask, it can be ensured that the first sub-oxygen storage section 41 completely covers the resistive switching section 30. After etching, the sidewall 60 is formed. This ensures that etching the sidewall 60 does not damage the surface of the resistive switching section 30, thus affecting device performance. Furthermore, during the subsequent fabrication of the second sub-oxygen storage section 42, even if a slight misalignment occurs, the resistive switching section 30 will not be exposed, allowing it to directly contact the upper electrode 50. Compared to a one-step fabrication method for the oxygen storage section 42, the fabrication method in this embodiment can appropriately reduce the precision requirements for die-casting alignment.

[0062] Please see Figure 6 , Figure 6 This is a schematic diagram of the resistive switching memory fabricated by the third fabrication method provided in this application embodiment. In this embodiment, the oxygen storage portion 40 is located on the side of the resistive switching portion 30 and is in electrical contact with the resistive switching portion 30. The fabrication method may include: S410, The bottom electrode is formed on the substrate.

[0063] For example, a first conductive layer can be formed on the substrate 100, and then a mask pattern can be fabricated and etched to obtain the bottom electrode 20.

[0064] S420, A sidewall is formed on the side of the bottom electrode.

[0065] For example, an isolation layer can be fabricated on the entire surface of the substrate, completely covering the bottom electrode 20, and then the isolation layer can be etched to retain only the side portion of the bottom electrode 20, thereby forming a sidewall 60 on the side of the bottom electrode 20.

[0066] S430. A first insulating portion is formed on the substrate, wherein the top surface of the first insulating portion is flush with the top surface of the sidewall.

[0067] For example, a first insulating layer covering the bottom electrode 20 and the sidewall 60 can be formed on the substrate 100, and then planarization can be performed to expose the bottom electrode 20 to form a first insulating portion 70, wherein the top surface of the first insulating portion 70 is flush with the top surface of the bottom electrode 20 / sidewall 60.

[0068] S440, The resistive switching section is formed on the top surface of the bottom electrode.

[0069] For example, a resistive switching layer can be formed on the top surface of the substrate 100, then a mask pattern can be fabricated and the resistive switching layer can be etched, and then the mask pattern can be removed, thereby forming a resistive switching portion 30 on the top surface of the bottom electrode 20.

[0070] S450, The oxygen storage section is formed on the side of the resistive switching section.

[0071] For example, an oxygen storage layer can be formed on the top surface of the substrate 100, covering the resistive switching portion 30 and the first insulating portion 70, and then planarized. A mask pattern is then fabricated to etch the oxygen storage layer, and the mask pattern is removed, thereby forming the oxygen storage portion 40 on the side of the resistive switching portion 30.

[0072] S460. A top electrode is formed on the side of the oxygen storage section, and the top electrode is in electrical contact with the oxygen storage section.

[0073] For example, a second conductive layer can be formed on the top surface of the substrate 100, covering the resistive switching part 30, the oxygen storage part 40 and the first insulating part 70, and then planarized. A mask pattern is then made to etch the second conductive layer, and the mask pattern is removed, thereby forming a top electrode 50 on the side of the oxygen storage part 40.

[0074] This application also provides a resistive switching memory, including: a substrate 100, a bottom electrode 20, a resistive switching portion 30, an oxygen storage portion 40, and a top electrode 50. The bottom electrode 20 is located on the substrate 100, the resistive switching portion 30 is located on the bottom electrode 20, the oxygen storage portion 40 is located on the resistive switching portion 30, or is horizontally adjacent to and electrically contacted with the resistive switching portion 30, and the top electrode 50 is horizontally adjacent to and electrically contacted with the oxygen storage portion 40.

[0075] The resistive random access memory in this application embodiment is "L" shaped, including two structural forms.

[0076] The first type consists of a substrate 100, a bottom electrode 20, a resistive switching section 30, and an oxygen storage section 40 stacked sequentially, with the top electrode 50 horizontally adjacent to and electrically contacting the oxygen storage section 40. Figure 4I and 5I As shown. In this structural configuration, the sidewall 60 can be formed on the sides of the bottom electrode 20 and the resistive switching part 30.

[0077] The second type involves a substrate 100, a bottom electrode 20, and a resistive switching section 30 stacked sequentially. The resistive switching section 30, the oxygen storage section 40, and the top electrode 50 are horizontally adjacent and electrically contacted. Figure 6 As shown. In this structural configuration, the sidewall 60 can be formed on the side of the bottom electrode 20.

[0078] In one embodiment, the oxygen storage unit 40 may include a first sub-oxygen storage unit 41 and a second sub-oxygen storage unit 42 that are stacked sequentially. For this structure, the sidewall 60 may be formed on the side of the bottom electrode 20 and the resistive switching unit 30, and may also cover the side of the first sub-oxygen storage unit 41.

[0079] For other structures and operating principles of the resistive random access memory in this embodiment, please refer to the description of the fabrication method of the resistive random access memory in the foregoing embodiments of the present invention, which will not be repeated here.

[0080] The foregoing has provided a detailed description of a resistive random access memory (RRAM) and its fabrication method. Specific examples have been used to illustrate the principles and implementation methods of this application. It should be noted that the descriptions of each embodiment in this application have different emphases; parts not described in detail in a particular embodiment can be referred to in the relevant descriptions of other embodiments.

[0081] It should be understood that the terms "comprising" or "including" indicate the presence of the stated features, steps, operations, elements, components, items, types, and / or groups, but do not exclude the presence, occurrence, or addition of one or more other features, steps, operations, elements, components, items, types, and / or groups. The terms "or," "and / or," and "comprising at least one of the following," as used in this application, can be interpreted as inclusive, or mean any one or any combination thereof. For example, "comprising at least one of the following: A, B, C" means "any one of the following: A; B; C; A and B; A and C; B and C; A and B and C," and similarly, "A, B, or C" or "A, B, and / or C" means "any one of the following: A; B; C; A and B; A and C; B and C; A and B and C." Exceptions to this definition only occur when the combination of elements, functions, steps, or operations is inherently mutually exclusive in some way.

[0082] It should be understood that although the terms first, second, third, etc., may be used in this document to describe various types of information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this document, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the singular forms “a,” “an,” and “the” used in this document are intended to also include the plural forms, unless the context indicates otherwise.

[0083] It should be understood that the terms "top", "bottom", "upper", "lower", "vertical", "horizontal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application.

[0084] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. The technical features of the technical solution of this application can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are also included within the patent protection scope of this application, as long as the combination of these technical features does not contradict each other.

Claims

1. A method for fabricating a resistive random access memory (RAD), characterized in that, include: A substrate is provided on which a bottom electrode, a resistive switching portion, and an oxygen storage portion are sequentially formed, wherein the resistive switching portion is located on the bottom electrode, the oxygen storage portion is located on the resistive switching portion, or the oxygen storage portion is located on the side of the resistive switching portion and is in electrical contact with the resistive switching portion; A top electrode is formed on the side of the oxygen storage section, and the top electrode is in electrical contact with the oxygen storage section.

2. The preparation method according to claim 1, characterized in that, When the oxygen storage portion is located on the resistive switching portion, a bottom electrode, a resistive switching portion, and an oxygen storage portion are sequentially formed on the substrate, specifically including: The bottom electrode and the resistive switching portion are formed on the substrate; An isolation layer is formed on the substrate, the isolation layer simultaneously covering the top surface of the substrate, the side surface of the bottom electrode, the side surface of the resistive switching part, and the top surface of the resistive switching part; The isolation layer is etched using the resistive switching portion as an etch stop layer to form sidewalls on the sides of the bottom electrode and the resistive switching portion; The oxygen storage section is formed on the top surface of the resistive switching section.

3. The preparation method according to claim 2, characterized in that, The oxygen storage unit also covers the side wall.

4. The preparation method according to claim 1, characterized in that, When the oxygen storage portion is located on the resistive switching portion, a bottom electrode, a resistive switching portion, and an oxygen storage portion are sequentially formed on the substrate, specifically including: The bottom electrode, the resistive switching section, and the first sub-oxygen storage section are formed on the substrate; An isolation layer is formed on the substrate, which simultaneously covers the top surface of the substrate, the side surface of the bottom electrode, the side surface of the resistive switching part, the side surface of the first sub-oxygen storage part, and the top surface of the first sub-oxygen storage part. The isolation layer is etched using the first sub-oxygen storage section as the etching stop layer to form sidewalls on the sides of the bottom electrode, the resistive switching section and the first sub-oxygen storage section. A second sub-oxygen storage unit is formed on the top surface of the first sub-oxygen storage unit, wherein the first sub-oxygen storage unit and the second sub-oxygen storage unit constitute the oxygen storage unit.

5. The preparation method according to claim 4, characterized in that, The bottom electrode, the resistive switching portion, and the first sub-oxygen storage portion are formed on the substrate, specifically including: A first conductive layer, a resistive switching layer, and a first oxygen storage layer are sequentially formed on the substrate; A mask pattern is formed in the first oxygen storage layer, and the first conductive layer, the resistive switching layer and the first oxygen storage layer are etched to obtain the bottom electrode, the resistive switching part and the first sub-oxygen storage part.

6. The preparation method according to claim 4, characterized in that, Before forming the second sub-oxygen storage unit on the top surface of the first sub-oxygen storage unit, the following is also included: A first insulating portion is formed on the substrate, wherein the first insulating portion is flush with the top surface of the first sub-oxygen storage portion; A second sub-oxygen storage unit is formed on the top surface of the first sub-oxygen storage unit, specifically including: A second oxygen storage layer is formed on the top surface of the first insulating part and the first sub-oxygen storage part; A mask pattern is formed on the top surface of the second oxygen storage layer, and the second oxygen storage layer is etched to obtain the second sub-oxygen storage section.

7. The preparation method according to any one of claims 1-6, characterized in that, A top electrode is formed on the side of the oxygen storage section, specifically including: A second conductive layer is formed on the entire surface of the substrate; The second conductive layer is planarized using the oxygen storage section as a CMP stop layer to obtain the top electrode.

8. The preparation method according to claim 1, characterized in that, When the oxygen storage portion is located on the side of the resistive switching portion and is in electrical contact with the resistive switching portion, a bottom electrode, a resistive switching portion, and an oxygen storage portion are sequentially formed on the substrate, specifically including: The bottom electrode is formed on the substrate; A sidewall is formed on the side of the bottom electrode; A first insulating portion is formed on the substrate, wherein the top surface of the first insulating portion is flush with the top surface of the sidewall; The resistive switching section is formed on the top surface of the bottom electrode; The oxygen storage section is formed on the side of the resistive switching section.

9. A resistive random access memory, characterized in that, include: Substrate; The bottom electrode is located on the substrate; The resistive switching section is located on the bottom electrode; An oxygen storage section is located on the resistive switching section, or is horizontally adjacent to and electrically contacted with the resistive switching section; The top electrode is horizontally adjacent to and electrically in contact with the oxygen storage section.

10. The resistive random access memory according to claim 9, characterized in that, It also includes sidewalls, which are formed on the sides of the bottom electrode and the resistive switching unit when the oxygen storage unit is located on the resistive switching unit.

11. The resistive random access memory according to claim 10, characterized in that, The oxygen storage unit includes a first sub-oxygen storage unit and a second sub-oxygen storage unit arranged in sequence. The sidewall also covers the side of the first sub-oxygen storage unit; The top electrode is horizontally adjacent to and electrically in contact with the second sub-oxygen storage unit.

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