A vertical spin-transfer torque magnetic random access memory and a preparation method thereof

Abstract

The present invention provides a vertical spin-transfer torque magnetic random access memory and a manufacturing method thereof, including a substrate, a fixed ferromagnetic layer composite structure, a trench, an insulating tunneling barrier layer, a free ferromagnetic layer, an intermediate metal connection structure, and a peripheral metal connection structure; the fixed ferromagnetic layer composite structure is located on the substrate and includes an insulating layer and a fixed ferromagnetic layer arranged alternately; the trench penetrates through the fixed ferromagnetic layer; the insulating tunneling barrier layer and the free ferromagnetic layer are sequentially located in the trench; the intermediate metal connection structure is located in the trench and covers the free ferromagnetic layer; the peripheral metal connection structure is located in the fixed ferromagnetic layer composite structure and is in contact with the fixed ferromagnetic layer and is correspondingly arranged. The vertical spin-transfer torque magnetic random access memory of the present invention is stacked and combined vertically by STT-MRAM. Under the same floor area, it can store double or more times the information, can improve the storage density of the storage device, and can improve the accuracy of "reading" and "writing" of each layer of the memory.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor technology, and relates to a vertical spin-transfer torque magnetic random access memory and a preparation method thereof. Background Art

[0002] Magnetoresistive Random Access Memory (MRAM) is a random access device, and its working principle is to use its resistance value rather than charge to store data. Its core includes a magnetic tunnel junction (MTJ) structure. By controlling the resistance of the MTJ, the "0" or "1" state of the storage structure is characterized.

[0003] The MTJ structure generally includes a fixed ferromagnetic layer and a free ferromagnetic layer, and is separated by an insulating tunneling barrier layer located between the fixed ferromagnetic layer and the free ferromagnetic layer, and the MTJ structure is clamped by a top electrode and a bottom electrode, so that current can flow between the top electrode and the bottom electrode.

[0004] Spin-transfer torque magnetic random access memory (STT-MRAM) is a new type of non-volatile magnetic random access memory that realizes information writing through spin current, and it is the second-generation product of the magnetic memory MRAM. The STT-MRAM storage unit changes the magnetization directions of the free ferromagnetic layer and the fixed ferromagnetic layer through a spin-polarized current, including the same direction or the opposite direction, to change the resistance value of the MTJ, so as to realize information recording.

[0005] However, in the existing spin-transfer torque magnetic random access memory, the fixed ferromagnetic layer, the insulating tunneling barrier layer, and the free ferromagnetic layer are often in a flat structure. In order to enhance the memory ability of the storage device, the footprint of the spin-transfer torque magnetic random access memory is usually large, and the storage density is low, which is not conducive to the application of the spin-transfer torque magnetic random access memory. Summary of the Invention

[0006] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a vertical spin-transfer torque magnetic random access memory and a preparation method thereof, which are used to solve the problems that the vertical spin-transfer torque magnetic random access memory in the prior art has a large footprint and a low storage density, and is not conducive to the application of the spin-transfer torque magnetic random access memory.

[0007] To achieve the above purpose and other related purposes, the present invention provides a vertical spin-transfer torque magnetic random access memory, and the vertical spin-transfer torque magnetic random access memory includes:

[0008] A substrate;

[0009] A fixed ferromagnetic layer composite structure, which is located on the substrate and includes an insulating layer and a fixed ferromagnetic layer arranged alternately, where the fixed ferromagnetic layer includes N layers, N≥2;

[0010] A trench, which is located in the fixed ferromagnetic layer composite structure and penetrates the fixed ferromagnetic layer;

[0011] An insulating tunneling barrier layer, which is located in the trench and covers the trench;

[0012] A free ferromagnetic layer, which is located in the trench and covers the insulating tunneling barrier layer;

[0013] An intermediate metal connection structure, which is located in the trench and covers the free ferromagnetic layer;

[0014] A peripheral metal connection structure, which is located in the fixed ferromagnetic layer composite structure, is arranged corresponding to the N layers of the fixed ferromagnetic layer, and is in contact with the fixed ferromagnetic layer.

[0015] Optionally, the value range of N includes 2≤N≤10000; the N peripheral metal connection structures are arranged in parallel, and the projections of the vertically adjacent peripheral metal connection structures have an included angle θ, and the value of the included angle θ is 0°≤θ≤90°.

[0016] Optionally, the cross-sectional morphology of the perpendicular spin-transfer torque magnetic random access memory includes one or a combination of a perfect circle, an ellipse, a square, and a rectangle.

[0017] Optionally, the ratio of the thickness of the fixed ferromagnetic layer to the thickness of the free ferromagnetic layer is 2-100; the fixed ferromagnetic layer includes one or more of Mn, Pt, Ir, Rh, Ni, Pd, Fe, and Os.

[0018] Optionally, the thickness of the free ferromagnetic layer is 1nm-1000nm; the free ferromagnetic layer includes one or more of Fe, NiCo, Ru, Ir, Rh, CoHf, Co, CoFeB, and CoZr.

[0019] Optionally, the thickness of the insulating tunneling barrier layer is 0.5nm-3.0nm; the insulating tunneling barrier layer includes one or more of MgO, AlO, and AlN.

[0020] Optionally, the intermediate metal connection structure includes one or more of Cu, Co, Al, Ti, Ta, W, Pt, Ni, Cr, Ru, TiN, TaN, and Ta; the peripheral metal connection structure includes one or more of Cu, Co, Al, Ti, Ta, W, Pt, Ni, Cr, Ru, TiN, TaN, and Ta.

[0021] The present invention also provides a method for manufacturing a vertical spin-transfer torque magnetic random access memory, comprising the following steps:

[0022] Providing a substrate;

[0023] Forming a pinned ferromagnetic layer composite structure on the substrate, the pinned ferromagnetic layer composite structure including an insulating layer and a pinned ferromagnetic layer arranged alternately, wherein the pinned ferromagnetic layer includes N layers, N≥2;

[0024] Forming a trench in the pinned ferromagnetic layer composite structure, and the trench penetrating through the pinned ferromagnetic layer;

[0025] Forming an insulating tunneling barrier layer in the trench, and the insulating tunneling barrier layer covering the trench;

[0026] Forming a free ferromagnetic layer in the trench, and the free ferromagnetic layer covering the insulating tunneling barrier layer;

[0027] Forming an intermediate metal connection structure in the trench, and the intermediate metal connection structure covering the free ferromagnetic layer;

[0028] Removing a part of the pinned ferromagnetic layer composite structure, and forming a peripheral metal connection structure in the pinned ferromagnetic layer composite structure, the peripheral metal connection structure being correspondingly arranged with the N-layer pinned ferromagnetic layer and being in contact with the pinned ferromagnetic layer.

[0029] Optionally, the value range of N includes 2≤N≤10000; the N peripheral metal connection structures are arranged in parallel, and the projections of the vertically adjacent peripheral metal connection structures have an included angle θ, and the value of the included angle θ is 0°≤θ≤90°.

[0030] Optionally, the cross-sectional morphology of the formed vertical spin-transfer torque magnetic random access memory includes one or a combination of a perfect circle, an ellipse, a square, and a rectangle.

[0031] As described above, the vertical spin-transfer torque magnetic random access memory and its manufacturing method of the present invention. The vertical spin-transfer torque magnetic random access memory includes a substrate, a fixed ferromagnetic layer composite structure, a trench, an insulating tunneling barrier layer, a free ferromagnetic layer, an intermediate metal connection structure, and a peripheral metal connection structure. Among them, the fixed ferromagnetic layer composite structure is located on the substrate and includes an insulating layer and a fixed ferromagnetic layer arranged alternately. Among them, the fixed ferromagnetic layer includes N layers, where N ≥ 2. The trench is located in the fixed ferromagnetic layer composite structure and penetrates the fixed ferromagnetic layer. The insulating tunneling barrier layer is located in the trench and covers the trench. The free ferromagnetic layer is located in the trench and covers the insulating tunneling barrier layer. The intermediate metal connection structure is located in the trench and covers the free ferromagnetic layer. The peripheral metal connection structure is located in the fixed ferromagnetic layer composite structure, is correspondingly arranged with the N layers of the fixed ferromagnetic layer, and is in contact with the fixed ferromagnetic layer.

[0032] The vertical spin-transfer torque magnetic random access memory of the present invention is composed of STT-MRAMs stacked vertically. The formed combination can store double or more information under the same floor area, which greatly helps to improve the storage density of the storage device. At the same time, the fixed ferromagnetic layers of each layer are not connected to each other, improving the accuracy of "reading" and "writing" of each layer of the memory. Therefore, the present invention can reduce the floor area of the vertical spin-transfer torque magnetic random access memory, facilitating the miniaturization of the vertical spin-transfer torque magnetic random access memory and the accuracy of "reading" and "writing". Description of the Drawings

[0033] Figure 1 It shows a schematic process flow diagram of manufacturing the vertical spin-transfer torque magnetic random access memory in an embodiment of the present invention.

[0034] Figure 2 It shows a schematic structural diagram of the substrate provided in an embodiment of the present invention.

[0035] Figure 3 It shows a schematic structural diagram after forming the fixed ferromagnetic layer composite structure in an embodiment of the present invention.

[0036] Figure 4 It shows a schematic structural diagram after forming the trench in an embodiment of the present invention.

[0037] Figure 5 It shows a schematic structural diagram after forming the insulating tunneling barrier layer in an embodiment of the present invention.

[0038] Figure 6 It shows a schematic structural diagram after forming the free ferromagnetic layer in an embodiment of the present invention.

[0039] Figure 7Schematic diagram of the structure after forming the intermediate metal connection structure in an embodiment of the present invention.

[0040] Figure 8 Schematic diagram of the structure after removing part of the fixed ferromagnetic layer composite structure in an embodiment of the present invention.

[0041] Figure 9 Schematic diagram of the structure after forming the peripheral metal connection structure in an embodiment of the present invention.

[0042] Figure 10 Shown as Figure 9 Cross-sectional structure diagram obtained along A-A' in

[0043] Figure 11 Shown as Figure 9 Cross-sectional structure diagram obtained along B-B' in

[0044] Figure 12 Shown as Figure 9 Top view structure diagram of

[0045] Figure 13 Schematic diagram showing a state when the perpendicular spin-transfer torque magnetic random access memory in an embodiment of the present invention performs "writing".

[0046] Figure 14 Another schematic diagram showing a state when the perpendicular spin-transfer torque magnetic random access memory in an embodiment of the present invention performs "writing".

[0047] Figure 15 Schematic diagram showing a state when the perpendicular spin-transfer torque magnetic random access memory in an embodiment of the present invention performs "reading".

[0048] Element number description

[0049] 100 Substrate

[0050] 200 Fixed ferromagnetic layer composite structure

[0051] 201 Insulating layer

[0052] 211 Groove

[0053] 300 Magnetic tunnel junction

[0054] 301 Fixed ferromagnetic layer

[0055] 302 Insulating tunneling barrier layer

[0056] 303 Free ferromagnetic layer

[0057] 400 Intermediate metal connection structure

[0058] 501 First peripheral metal connection structure

[0059] 502 Second Peripheral Metal Connection Structure

[0060] 503 Third Peripheral Metal Connection Structure

[0061] 504 Fourth Peripheral Metal Connection Structure

[0062] T STT-MRAM

[0063] Steps S1 to S7 Detailed Implementation Manner

[0064] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0065] When detailing the embodiments of the present invention, for the convenience of description, the cross-sectional views showing the device structure will be enlarged locally in a non-general proportion, and the schematic diagrams are only examples and should not limit the protection scope of the present invention herein. In addition, in actual production, three-dimensional spatial dimensions including length, width, and depth should be included.

[0066] For the convenience of description, spatial relationship terms such as "under", "below", "lower than", "beneath", "above", "on", etc. may be used herein to describe the relationship between one element or feature shown in the drawings and other elements or features. It will be understood that these spatial relationship terms are intended to include other directions of the device in use or operation besides the directions depicted in the drawings. In addition, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or there can also be one or more intermediate layers. The "between... and..." used herein means including the endpoint values.

[0067] In the context of the present application, the structure in which the first feature is "above" the second feature may include an embodiment where the first and second features are formed in direct contact, and may also include an embodiment where additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0068] It should be noted that the drawings provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the drawings, rather than being drawn according to the number, shape, and size of the components in actual implementation. The types, quantities, and ratios of the components in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0069] Such asFigures 2 to 9 , this embodiment provides a vertical spin-transfer torque magnetic random access memory. The vertical spin-transfer torque magnetic random access memory includes a substrate 100, a fixed ferromagnetic layer composite structure 200, a trench 211, an insulating tunneling barrier layer 302, a free ferromagnetic layer 303, an intermediate metal connection structure 400, and a peripheral metal connection structure. Among them, the fixed ferromagnetic layer composite structure 200 is located on the substrate 100 and includes an insulating layer 201 and a fixed ferromagnetic layer 302 arranged alternately. Among them, the fixed ferromagnetic layer 302 includes N layers, where N≥2; the trench 211 is located in the fixed ferromagnetic layer composite structure 200 and penetrates the fixed ferromagnetic layer 301; the insulating tunneling barrier layer 302 is located in the trench 211 and covers the trench 211; the free ferromagnetic layer 303 is located in the trench 211 and covers the insulating tunneling barrier layer 302; the intermediate metal connection structure 400 is located in the trench 211 and covers the free ferromagnetic layer 303; the peripheral metal connection structure is located in the fixed ferromagnetic layer composite structure 200, is correspondingly arranged with the N layers of the fixed ferromagnetic layer 301, and is in contact with the fixed ferromagnetic layer 301.

[0070] The vertical spin-transfer torque magnetic random access memory of this embodiment is formed by vertically stacking and combining STT-MRAMs. The formed combination can store double or more times the information under the same floor area, which greatly helps to improve the storage density of the storage device. At the same time, the fixed ferromagnetic layers 301 of each layer are not connected to each other, which can improve the accuracy of "reading" and "writing" of each layer of the memory, thereby reducing the floor area of the vertical spin-transfer torque magnetic random access memory, facilitating the miniaturization of the vertical spin-transfer torque magnetic random access memory, and the accuracy of "reading" and "writing".

[0071] As an example, the value range of N includes 2≤N≤10000; the N peripheral metal connection structures are arranged in parallel, and the projections of the vertically adjacent peripheral metal connection structures have an included angle θ, and the value of the included angle θ is 0°≤θ≤90°.

[0072] Specifically, as Figure 9 , in this embodiment, the vertical spin-transfer torque magnetic random access memory includes 4 Ts, that is, STT-MRAMs stacked. Among them, the value of N is 4, but it is not limited thereto. The value of N in the vertical spin-transfer torque magnetic random access memory can also be set to 2, 3, 5, 10, 100, 1000, 10000, etc., and can be specifically set according to needs, and no excessive restrictions are made here.

[0073] Furthermore, as Figure 12Schematically shows a top view structural schematic diagram of the vertical spin-transfer torque magnetic random access memory. Among them, for the convenience of electrical connection, it is preferable to stagger the peripheral metal connection structures in the vertical spin-transfer torque magnetic random access memory, that is, there is a height difference and they are arranged in parallel between the first peripheral metal connection structure 501, the second peripheral metal connection structure 502, the third peripheral metal connection structure 503 and the fourth peripheral metal connection structure 504, and an included angle θ is formed between the projections of adjacent peripheral metal connection structures along the vertical direction. Among them, the value of the included angle θ can include 0°≤θ≤90°, such as 30°, 45°, 60°, 90°, etc., for staggered arrangement, so as to provide reserved space for subsequent electrical connection and reduce the device size, which can be specifically set according to needs.

[0074] As an example, the morphology of the cross-section of the vertical spin-transfer torque magnetic random access memory includes one or a combination of a perfect circle, an ellipse, a square, and a rectangle.

[0075] Specifically, such as Figure 10 and Figure 11 Schematically shows a cross-sectional structural schematic diagram of the vertical spin-transfer torque magnetic random access memory. The cross-section of the STT-MRAM in this embodiment is a perfect circle, but it is not limited thereto. The cross-section of the STT-MRAM can also be one of an ellipse, a square, a rectangle or a combination of a perfect circle, an ellipse, a square, and a rectangle, and no excessive limitation is made here.

[0076] As an example, the ratio of the thickness of the fixed ferromagnetic layer 301 to the thickness of the free ferromagnetic layer 303 can be 2 - 100; the fixed ferromagnetic layer 301 can include one or more of Mn and Pt, Ir, Rh, Ni, Pd, Fe, and Os, such as FeMn, IrMn, PtMn, MnO, MnS, MnTe, MnF2, FeF2, FeCl2, FeO, CoCl2, CoO, etc. The ratio of the thickness of the fixed ferromagnetic layer 301 to the thickness of the free ferromagnetic layer 303 can be 2, 10, 50, 100, etc., and can be specifically selected according to needs, and no excessive limitation is made here.

[0077] As an example, the thickness of the free ferromagnetic layer 303 can be 1 nm - 1000 nm; the free ferromagnetic layer 303 can include one or more of Fe, NiCo, Ru, Ir, Rh, CoHf, Co, CoFeB, and CoZr.

[0078] Specifically, the thickness of the free ferromagnetic layer 303 can be any one of 1 nm, 10 nm, 100 nm, 500 nm, and 1000 nm. Among them, the material of the free ferromagnetic layer 303 can include one or more of Fe, NiCo, Ru, Ir, Rh, CoHf, Co, CoFeB, and CoZr. The specific type can be selected according to needs and will not be overly restricted here.

[0079] As an example, the thickness of the insulating tunneling barrier layer 302 can be 0.5 nm - 3.0 nm; the insulating tunneling barrier layer 302 can include one or more of MgO, AlO, and AlN.

[0080] Specifically, the thickness of the insulating tunneling barrier layer 302 can be any one of 0.5 nm, 1.0 nm, 2.0 nm, 3.0 nm, etc. Among them, the material of the insulating tunneling barrier layer 302 can be composed of one or more of MgO, AlO, and AlN. The specific type can be selected according to needs and will not be overly restricted here.

[0081] As an example, the intermediate metal connection structure 400 includes one or more of Cu, Co, Al, Ti, Ta, W, Pt, Ni, Cr, Ru, TiN, TaN, and Ta; the peripheral metal connection structure includes one or more of Cu, Co, Al, Ti, Ta, W, Pt, Ni, Cr, Ru, TiN, TaN, and Ta.

[0082] Refer to Figure 1 , this embodiment also provides a method for manufacturing a vertical spin-transfer torque magnetic random access memory, including the following steps:

[0083] S1: Provide a substrate;

[0084] S2: Form a pinned ferromagnetic layer composite structure on the substrate. The pinned ferromagnetic layer composite structure includes an insulating layer and a pinned ferromagnetic layer arranged alternately. Among them, the pinned ferromagnetic layer includes N layers, N ≥ 2;

[0085] S3: Form a trench in the pinned ferromagnetic layer composite structure, and the trench penetrates the pinned ferromagnetic layer;

[0086] S4: Form an insulating tunneling barrier layer in the trench, and the insulating tunneling barrier layer covers the trench;

[0087] S5: Form a free ferromagnetic layer in the trench, and the free ferromagnetic layer covers the insulating tunneling barrier layer;

[0088] S6: Form an intermediate metal connection structure in the trench, and the intermediate metal connection structure covers the free ferromagnetic layer

[0089] S7: Remove part of the fixed ferromagnetic layer composite structure, and form a peripheral metal connection structure in the fixed ferromagnetic layer composite structure. The peripheral metal connection structure is correspondingly arranged with the N layers of the fixed ferromagnetic layer and is in contact with the fixed ferromagnetic layer.

[0090] Specifically, as Figures 2 to 9 , the steps for preparing the perpendicular spin-transfer torque magnetic random access memory in this embodiment will be further described below with reference to the accompanying drawings, which are as follows:

[0091] First, as Figure 2 , perform step S1 to provide a substrate 100.

[0092] Specifically, the substrate 100 may be an SOI substrate including a bottom silicon layer, a buried oxide layer, and a top silicon layer. Of course, it may also be a silicon substrate, a germanium substrate, a sapphire substrate, a silicon carbide substrate, etc. The specific type of the substrate 100 is not overly restricted here. In this embodiment, only a silicon substrate is taken as an example.

[0093] Next, as Figure 3 , perform step S2 to form a fixed ferromagnetic layer composite structure 200 on the substrate 100. The fixed ferromagnetic layer composite structure 200 includes insulating layers 201 and fixed ferromagnetic layers 301 arranged alternately. Among them, the fixed ferromagnetic layer 301 includes N layers, and N≥2.

[0094] Specifically, as Figure 3 , the insulating layer 201 and the fixed ferromagnetic layer 301 can be sequentially deposited on the substrate 100. Among them, the insulating layer 201 may include an insulating dielectric layer such as a silicon oxide layer prepared by chemical vapor deposition. The preparation method, type, and thickness of the insulating layer 201 are not overly restricted here. In this embodiment, the value of N is taken as N = 4, but it is not limited thereto. N can also be 2, 3, 5, 10, 100, 1000, 10000, etc., and can be specifically set according to needs, which is not overly restricted here.

[0095] Among them, the fixed ferromagnetic layer 301 can be deposited and prepared by using one of the processes such as CVD, MOCVD, PVD, ALD, etc. This is not overly restricted here. The fixed ferromagnetic layer 301 may include one or more of Mn, Pt, Ir, Rh, Ni, Pd, Fe, and Os, such as FeMn, IrMn, PtMn, MnO, MnS, MnTe, MnF2, FeF2, FeCl2, FeO, CoCl2, CoO, etc.

[0096] Next, as Figure 4, perform step S3 to form a trench 211 in the fixed ferromagnetic layer composite structure 200, and the trench 211 penetrates through the fixed ferromagnetic layer 301.

[0097] Specifically, the fixed ferromagnetic layer composite structure 200 can be etched, such as by dry etching, to form the trench 211 that penetrates through the fixed ferromagnetic layer 301 in the fixed ferromagnetic layer composite structure 200, so as to facilitate the subsequent preparation of the insulating tunneling barrier layer 302 that contacts each layer of the fixed ferromagnetic layer 301.

[0098] Next, as Figure 5 , perform step S4 to form an insulating tunneling barrier layer 302 in the trench 211, and the insulating tunneling barrier layer 302 covers the trench 211.

[0099] Specifically, the insulating tunneling barrier layer 302 can be deposited and prepared by using one of the processes such as CVD, MOCVD, PVD, ALD, etc. There is no excessive limitation here. The thickness of the insulating tunneling barrier layer 302 can be 0.5 nm - 3.0 nm, such as 0.5 nm, 1.0 nm, 2.0 nm, 3.0 nm, etc. The insulating tunneling barrier layer 302 can include one or more of MgO, AlO, and AlN.

[0100] Next, as Figure 6 , perform step S5 to form a free ferromagnetic layer 303 in the trench 211, and the free ferromagnetic layer 303 covers the insulating tunneling barrier layer 302.

[0101] Specifically, the free ferromagnetic layer 303 can be deposited and prepared by using one of the processes such as CVD, MOCVD, PVD, ALD, etc. There is no excessive limitation here. The thickness of the free ferromagnetic layer 303 can be 1 nm - 1000 nm, such as any one of 1 nm, 10 nm, 100 nm, 500 nm, 1000 nm; the free ferromagnetic layer 303 can include one or more of Fe, NiCo, Ru, Ir, Rh, CoHf, Co, CoFeB, and CoZr.

[0102] Next, as Figure 7 , perform step S6 to form an intermediate metal connection structure 400 in the trench 211, and the intermediate metal connection structure 400 covers the free ferromagnetic layer 303.

[0103] Specifically, CVD, MOCVD, PVD, ECP, electroless plating, etc. can be used to form the intermediate metal connection structure 400, and the material of the intermediate metal connection structure 400 can be one or a combination of, for example, Cu, Co, Al, Ti, Ta, W, Pt, Ni, Cr, Ru, TiN, TaN, Ta. In this embodiment, the intermediate metal connection structure 400 fills the trench 211 and is perpendicularly arranged with respect to the substrate 100, but is not limited thereto.

[0104] Next, as Figure 8 and Figure 9 , step S7 is executed to remove part of the fixed ferromagnetic layer composite structure 200 to form a peripheral metal connection structure in the fixed ferromagnetic layer composite structure 200. The peripheral metal connection structure is correspondingly arranged with N layers of the fixed ferromagnetic layer 301 and is in contact with the fixed ferromagnetic layer 301.

[0105] Specifically, dry etching can be used to remove part of the fixed ferromagnetic layer composite structure 200 to expose the fixed ferromagnetic layer 301, so as to facilitate the subsequent formation of the peripheral metal connection structure in contact with the fixed ferromagnetic layer 301. As Figure 9 , it includes steps of depositing an insulating layer 201 and depositing a peripheral metal connection structure to form the spaced-apart peripheral metal connection structures in the fixed ferromagnetic layer composite structure 200, including a first peripheral metal connection structure 501, a second peripheral metal connection structure 502, a third peripheral metal connection structure 503, and a fourth peripheral metal connection structure 504 from bottom to top. Thus, the peripheral metal connection structure is correspondingly arranged with N layers of the fixed ferromagnetic layer 301 to constitute N STT-MRAMs stacked from bottom to top.

[0106] Wherein, after forming the peripheral metal connection structure, a planarization process is included to expose the intermediate metal connection structure 400. The planarization process includes CMP, but is not limited thereto.

[0107] Refer to Figure 13 and Figure 14 which respectively show two schematic diagrams of the vertical spin-transfer torque magnetic random access memory during the "write" operation. Figure 15 shows a schematic diagram of the vertical spin-transfer torque magnetic random access memory during the "read" operation.

[0108] Specifically, Figure 13The arrow lines therein represent the current direction. In the "write" initial state: the current flows through the middle metal connection structure 400 to the first peripheral metal connection structure 501, the second peripheral metal connection structure 502, the third peripheral metal connection structure 503, and the fourth peripheral metal connection structure 504 respectively. Since the current flows from the free ferromagnetic layer 303 to the fixed ferromagnetic layer 301, the resistance between the middle metal connection structure 400 and each layer of the peripheral metal connection structures is the highest at this time. This state is defined as the initial state of the memory. This resistance state is denoted as state "1111".

[0109] Refer to Figure 14 The arrow lines represent the current direction. The current flows through the first peripheral metal connection structure 501 to the middle metal connection structure 400. Since the current flows from the fixed ferromagnetic layer 301 to the free ferromagnetic layer 303, the resistance between the middle metal connection structure 400 and the first peripheral metal connection structure 501 is the lowest at this time. This state is recorded by the first-layer memory. This resistance state is denoted as state "0111". Similarly, the current can change the states of each layer of the memory through each layer of the peripheral metal connection structures. They are respectively denoted as states "1011", "1101", "1110", "0011", "0101", "0110", "1001", "1010", "1100", "1000", "0100", "0010", "0001", "0000", etc.

[0110] Refer to Figure 15 The arrow lines represent the current direction. A relatively small current is input through the first peripheral metal connection structure 501 to measure the resistance between the first peripheral metal connection structure 501 and the middle metal connection structure 400, and to measure the storage state of the first-layer storage device. By analogy, the storage states of the first-layer memory, the second-layer memory, the third-layer memory, and the fourth-layer memory can be measured respectively.

[0111] In summary, the vertical spin-transfer torque magnetic random access memory of the present invention and its manufacturing method. The vertical spin-transfer torque magnetic random access memory includes a substrate, a fixed ferromagnetic layer composite structure, a trench, an insulating tunneling barrier layer, a free ferromagnetic layer, an intermediate metal connection structure, and a peripheral metal connection structure. Among them, the fixed ferromagnetic layer composite structure is located on the substrate and includes an insulating layer and a fixed ferromagnetic layer arranged alternately. The fixed ferromagnetic layer includes N layers, where N≥2. The trench is located in the fixed ferromagnetic layer composite structure and penetrates the fixed ferromagnetic layer. The insulating tunneling barrier layer is located in the trench and covers the trench. The free ferromagnetic layer is located in the trench and covers the insulating tunneling barrier layer. The intermediate metal connection structure is located in the trench and covers the free ferromagnetic layer. The peripheral metal connection structure is located in the fixed ferromagnetic layer composite structure, corresponding to the N layers of the fixed ferromagnetic layer and in contact with the fixed ferromagnetic layer.

[0112] The vertical spin-transfer torque magnetic random access memory of the present invention is composed of vertically stacked STT-MRAMs. The formed combination can store double or more information under the same floor area, which greatly helps to improve the storage density of the storage device. At the same time, the fixed ferromagnetic layers of each layer are not connected to each other, improving the accuracy of "reading" and "writing" of each layer of the memory. Therefore, the present invention can reduce the floor area of the vertical spin-transfer torque magnetic random access memory, facilitating the miniaturization of the vertical spin-transfer torque magnetic random access memory and the accuracy of "reading" and "writing".

[0113] The above embodiments merely illustrate the principles and effects of the present invention and are not used to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A perpendicular spin-transfer torque magnetic random access memory, characterized in that, The vertical spin-transfer torque magnetic random access memory includes: A substrate; A pinned ferromagnetic layer composite structure, which is located on the substrate and includes an insulating layer and a pinned ferromagnetic layer arranged alternately. Among them, the pinned ferromagnetic layer includes N layers, where N≥2; A trench, which is located in the pinned ferromagnetic layer composite structure and penetrates the pinned ferromagnetic layer; An insulating tunneling barrier layer, which is located in the trench and covers the trench; A free ferromagnetic layer, which is located in the trench and covers the insulating tunneling barrier layer; An intermediate metal connection structure, which is located in the trench and covers the free ferromagnetic layer; A peripheral metal connection structure, which is located in the pinned ferromagnetic layer composite structure, is correspondingly arranged with the N-layer pinned ferromagnetic layer, and is in contact with the pinned ferromagnetic layer.

2. The perpendicular spin-transfer torque magnetic random access memory according to claim 1, wherein: The value range of N includes 2≤N≤10000; the N peripheral metal connection structures are arranged in parallel, and the projections of the vertically adjacent peripheral metal connection structures have an included angle θ, and the value of the included angle θ is 0°≤θ≤90°.

3. The perpendicular spin-transfer torque magnetic random access memory according to claim 1, wherein: The cross-sectional morphology of the vertical spin-transfer torque magnetic random access memory includes one or a combination of a perfect circle, an ellipse, a square, and a rectangle.

4. The perpendicular spin-transfer torque magnetic random access memory according to claim 1, wherein: The ratio of the thickness of the pinned ferromagnetic layer to the thickness of the free ferromagnetic layer is 2-100; the pinned ferromagnetic layer includes one or more of Mn, Pt, Ir, Rh, Ni, Pd, Fe, and Os.

5. The perpendicular spin transfer torque magnetic random access memory according to claim 1, characterized in that: The thickness of the free ferromagnetic layer is 1nm-1000nm; the free ferromagnetic layer includes one or more of Fe, NiCo, Ru, Ir, Rh, CoHf, Co, CoFeB, and CoZr.

6. The perpendicular spin-transfer torque magnetic random access memory according to claim 1, wherein: The thickness of the insulating tunneling barrier layer is 0.5nm-3.0nm; the insulating tunneling barrier layer includes one or more of MgO, AlO, and AlN.

7. The perpendicular spin-transfer torque magnetic random access memory according to claim 1, wherein: The intermediate metal connection structure includes one or more of Cu, Co, Al, Ti, W, Pt, Ni, Cr, Ru, TiN, TaN, and Ta; the peripheral metal connection structure includes one or more of Cu, Co, Al, Ti, W, Pt, Ni, Cr, Ru, TiN, TaN, and Ta.

8. A method for preparing a perpendicular spin-transfer torque magnetic random access memory, characterized in that, Including the following steps: Providing a substrate; Forming a pinned ferromagnetic layer composite structure on the substrate, the pinned ferromagnetic layer composite structure includes an insulating layer and a pinned ferromagnetic layer arranged alternately, where the pinned ferromagnetic layer includes N layers, N≥2; Forming a trench in the pinned ferromagnetic layer composite structure, and the trench penetrates the pinned ferromagnetic layer; Forming an insulating tunneling barrier layer in the trench, and the insulating tunneling barrier layer covers the trench; Forming a free ferromagnetic layer in the trench, and the free ferromagnetic layer covers the insulating tunneling barrier layer; Forming an intermediate metal connection structure in the trench, and the intermediate metal connection structure covers the free ferromagnetic layer; Remove a part of the fixed ferromagnetic layer composite structure, and form a peripheral metal connection structure in the fixed ferromagnetic layer composite structure. The peripheral metal connection structure is correspondingly arranged with the N fixed ferromagnetic layers, and is in contact with the fixed ferromagnetic layer.

9. The manufacturing method of the perpendicular spin-transfer torque magnetic random access memory according to claim 8, wherein: The value range of N includes 2 ≤ N ≤ 10,000; the N peripheral metal connection structures are arranged in parallel, and the projections of the vertically adjacent peripheral metal connection structures have an included angle θ, and the value of the included angle θ is 0° ≤ θ ≤ 90°.

10. The manufacturing method of the perpendicular spin-transfer torque magnetic random access memory according to claim 8, wherein: The cross-sectional morphology of the formed perpendicular spin-transfer torque magnetic random access memory includes one or a combination of a perfect circle, an ellipse, a square, and a rectangle.

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