Magnetic memory device and method of manufacturing the same

Abstract

The application provides a magnetic memory device and a manufacturing method thereof. The device comprises a magnetic thin film structure and electrodes on the four sides of the magnetic thin film structure to control the magnetic anisotropy of the magnetic thin film structure. The manufacturing method comprises the following steps: preparing a bottom electrode, preparing a magnetic thin film structure on the bottom electrode, preparing a non-magnetic thin film structure on the magnetic thin film structure, preparing another magnetic thin film structure on the non-magnetic thin film structure, then making the two magnetic thin film structures and the non-magnetic thin film structure into a device, preparing an insulating layer film on the outer surface of the device, preparing VCMA electrodes on the four sides of the magnetic thin film structure which needs to be applied with voltage, and finally preparing wires to connect the VCMA electrodes with the outside. The VCMA electrodes of the application are generated from the sides of the magnetic thin film structure and do not affect the non-magnetic thin film structure, thus reducing the magnetic anisotropy. In the meantime, the application of the spin transfer torque writing mode to the MTJ can reduce the energy consumption of information writing and significantly improve the durability of the non-magnetic thin film structure.

Description

Technical Field

[0001] This invention relates to the field of memory chips in integrated circuits, and more specifically to a magnetic memory device and its manufacturing method. Background Technology

[0002] Due to factors such as short-channel effects resulting from miniaturization, standby power consumption (i.e., volatility) of random access memories (RAM, DRAM, etc.) based on MOSFETs at technology nodes below 20 nanometers is relatively severe. Next-generation integrated circuits require memory chips based on new, non-volatile principles. Magnetic Random Access Memory (MRAM), based on a spintronic magnetic tunnel junction (MTJ), is the most promising memory chip for large-scale application in next-generation integrated circuits. The performance of MTJ is primarily determined by the information writing method. The widely used spin transfer torque (STT) method, which already has small-scale products, is a major obstacle to its large-scale application in integrated circuits due to its high information writing power consumption and the resulting decrease in endurance. The recently popular information writing method, spin orbit torque (SOT), while offering lower information writing power, requires a long spin Hall channel, resulting in a larger device size and making it difficult to fabricate highly integrated memory chips. Another writing method, Voltage Controlled Magnetic Anisotropy (VCMA), suffers from a higher error rate due to its writing principle, making it impractical. Furthermore, it should be noted that, due to manufacturing limitations, the voltage applied to currently reported VCMA systems is typically applied to a cross-section containing an insulating layer within a vertically oriented ferromagnetic system, rather than to its sides or perimeter.

[0003] Current literature proposes using STT and VCMA together to write information into the MTJ, but the location of the applied VCMA voltage is not around the sides of the MTJ as proposed in this invention, but rather at an interface containing an insulating layer within the thin film surface of the MTJ free layer, as previously described (PHYSICAL REVIEW APPLIED. 15, 2021, 054055). The biggest problem with this type of structure is the questionable correctness of its physical mechanism. Physically, it is impossible to explain whether the STT effect already includes VCMA; that is, it is impossible to distinguish which part of the voltage and how much voltage will perform STT spin transfer, and which part of the voltage and how much voltage will generate VCMA. Moreover, the biggest problem is that the VCMA of this type of structure also affects the non-magnetic thin film structure, thus failing to improve the durability of the MTJ.

[0004] In conclusion, it is necessary to further innovate existing technologies. Summary of the Invention

[0005] To address the problems existing in the above-mentioned background technology, the present invention provides a magnetic memory device and its manufacturing method that uses STT and VCMA to jointly write information to MTJ. Its structure design is reasonable and the fabrication process is relatively simple. VCMA is generated from the side of the magnetic thin film structure and does not affect the non-magnetic thin film structure. Therefore, it can reduce magnetic anisotropy, thereby helping STT reduce the energy consumption of information writing, while also improving the durability of the non-magnetic thin film structure.

[0006] To solve the above-mentioned technical problems, the present invention provides a magnetic memory device, including a magnetic thin film structure, and the magnetic thin film structure has electrodes on its sides around which a voltage can be applied to control its magnetic anisotropy.

[0007] The method for manufacturing the magnetic memory device includes: the device comprising two magnetic thin film structures and a non-magnetic thin film structure sandwiched between the two magnetic thin film structures; one of the magnetic thin film structures has a VCMA electrode on its side that can be subjected to a voltage to control its magnetic anisotropy.

[0008] The method for manufacturing the magnetic memory device includes: both magnetic thin film structures are ferromagnetic thin film structures; an insulating layer film is provided around the sides of the structure composed of the two ferromagnetic thin film structures and the non-magnetic thin film structure; and a VCMA electrode is provided on the outer side of the insulating layer film, which can apply a voltage to one of the ferromagnetic thin film structures to control the magnetic anisotropy.

[0009] The method for manufacturing the magnetic memory device, wherein: the VCMA electrode can be connected to the outer surface of the insulating film by any one of the following connection methods: completely surrounding the outer surface of the insulating film, partially surrounding the outer surface of the insulating film, or partially contacting the outer surface of the insulating film.

[0010] The method for manufacturing the magnetic memory device, wherein the VCMA electrode can be any one of a multilayer heterostructure composed of different materials or a single structure composed of the same material.

[0011] A method for manufacturing a magnetic memory device involves first fabricating a bottom electrode, then fabricating a magnetic thin film structure on the fabricated bottom electrode, followed by fabricating a non-magnetic thin film structure on the fabricated magnetic thin film structure, then fabricating another magnetic thin film structure on the non-magnetic thin film structure, then etching the two magnetic thin film structures and the non-magnetic thin film structure to form an MTJ device, then fabricating an insulating thin film on the outer surface of the MTJ device, then fabricating VCMA electrodes around the sides of the magnetic thin film structure to which voltage needs to be applied, and finally fabricating wires connecting the VCMA electrodes to the outside world.

[0012] The method for manufacturing the magnetic memory device, wherein the method for fabricating VCMA electrodes on the periphery of one of the magnetic thin film structures to which a voltage can be applied, mainly includes the following steps:

[0013] (1.1) Deposit an insulating thin film on the surface of the MTJ device;

[0014] (1.2) Then deposit an insulating isolation layer on the part of the MTJ device where no voltage needs to be applied;

[0015] (1.3) Then deposit a sacrificial layer with a different etch selectivity than the insulating isolation layer in step (1.2) at the location where voltage needs to be applied to the MTJ device, and etch the sacrificial layer to form the desired pattern.

[0016] (1.4) Then deposit an insulating isolation layer on top of the sacrificial layer obtained in step (1.3);

[0017] (1.5) Then deposit electrode material at one end of the magnetic thin film structure to which voltage needs to be applied, etch the electrode material, and make it non-overlapping with the sacrificial layer after etching in step (1.3) from a top view angle, and then cover it with an insulating isolation layer and grind it flat.

[0018] (1.6) Then, etch holes above the sacrificial layer that does not overlap with the electrode material in step (1.5) until the sacrificial layer is in contact, and etch away the sacrificial layer;

[0019] (1.7) Deposit a VCMA electrode at the location where the sacrificial layer was etched away in step (1.6);

[0020] (1.8) Then etch away the excess electrode material at the location of the hole in step (1.6) and deposit the wires connecting the electrode material to the outside world to finally form a VCMA electrode that can apply voltage to the magnetic thin film structure.

[0021] The method for manufacturing the magnetic memory device, wherein the method for fabricating VCMA electrodes on the periphery of one of the magnetic thin film structures to which a voltage can be applied, may further be performed according to the following main steps:

[0022] (2.1) Deposit an insulating thin film on the surface of the MTJ device;

[0023] (2.2) The insulating layer and VCMA electrode are deposited by either of the following two methods: first depositing an insulating isolation layer on the part of the MTJ device where no voltage is required and then depositing a VCMA electrode to the required thickness on the periphery of the magnetic thin film structure of the MTJ device where voltage is required, or first depositing a VCMA electrode to the required thickness on the periphery of the magnetic thin film structure of the MTJ device where voltage is required and then depositing an insulating isolation layer on the part of the MTJ device where no voltage is required.

[0024] (2.3) The VCMA electrode obtained in step (2.2) is protected by covering it with an insulating layer.

[0025] The method for manufacturing the magnetic memory device, wherein step (2.2) may further involve depositing the VCMA electrode beyond the thickness of the MTJ device and then etching it back to the required thickness.

[0026] The method for manufacturing the magnetic memory device, wherein the method for fabricating VCMA electrodes on the periphery of one of the magnetic thin film structures to which a voltage can be applied, may also be performed according to the following main steps:

[0027] (3.1) Deposit an insulating thin film on the surface of the MTJ device;

[0028] (3.2) Then deposit a VCMA electrode on the outer surface of the insulating film;

[0029] (3.3) Then etch away the excess VCMA electrode so that the VCMA electrode surrounds the periphery of the magnetic thin film structure to which voltage needs to be applied.

[0030] By adopting the above technical solution, the present invention has the following beneficial effects:

[0031] The magnetic memory device of this invention has a reasonable structural design. An insulating thin film surrounds the sides of the magnetic thin film structure, and a VCMA electrode that can apply voltage to the magnetic thin film structure is added around the insulating thin film. The VCMA electrode also has a wire deposited on it to connect to the outside world. The purpose of using VCMA is to control the spin-electron magnetic anisotropy (VCMA) of the magnetic thin film structure by voltage during information writing, so as to work together with the STT method to write information. This can help STT reduce the energy consumption of information writing and improve the durability of non-magnetic thin film structures, making it suitable for promotion and application. Attached Figure Description

[0032] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the magnetic memory device according to Embodiment 1 of the present invention, that is, a schematic diagram of an information memory device that uses VCMA and STT to write information to MTJ.

[0034] Figure 2 This is another embodiment of the magnetic memory device of the present invention, namely, another structural schematic diagram of an information memory device that uses VCMA and STT to write information to MTJ.

[0035] Figures 3-6 This is a flowchart illustrating the fabrication method of the magnetic memory device according to Embodiment 1 of the present invention;

[0036] in, Figure 3 Figure (A) shows the fabrication of the bottom electrode and multilayer film of the MTJ. Figure 3 The middle figure (B) shows the formation of a vertical columnar MTJ device; Figure 3 The middle image (C) shows the formation of the insulating protective film; Figure 3 The middle diagram (D) shows the formation of the SiO2 protective layer between the fixing layer and the tunnel insulation layer; Figure 3 The middle figure (E) shows the deposition of a Si3N4 sacrificial film; Figure 3 The middle image (F) shows the etch-back of the Si3N4 sacrificial film; Figure 4 The middle image (G) shows the formation of the photoresist layer; Figure 4 The middle image (H) shows the etching of the sacrificial layer; Figure 4 Figure (I) shows the formation and planarization of the SiO2 capping layer; Figure 4 The middle image (J) shows etched holes; Figure 4The middle image (K) shows the etching process to remove the sacrificial layer; Figure 4 The middle image (L) shows the deposition of the VCMA electrode; Figure 5 The middle image (M) shows the removal of electrode material from the hole after drilling. Figure 5 The middle diagram (N) shows the filling of the hole with insulation; Figure 5 The middle image (O) shows CMP grinding until the free layer is exposed; Figure 5 The middle image (P) shows the electrode forming the free layer; Figure 5 The middle image (Q) shows the etched electrode to the desired shape; Figure 5 The middle image (R) shows the filling of insulation material and the surface being ground smooth; Figure 6 The middle image (S) shows the punched hole; Figure 6 The middle figure (T) is a schematic diagram of the structure of the final device obtained by forming VCMA electrodes;

[0037] Figure 7 This invention provides a method for preparing a VCMA electrode capable of applying voltage to a free layer.

[0038] in, Figure 7 The middle figure (A) shows the formation of a vertical columnar magnetic body; Figure 7 Figure B shows the deposition of the insulating film; Figure 7 The middle figure (C) shows the deposition of the VCMA electrode layer; Figure 7 The middle figure (D) shows the formation of the electrode covering insulating layer;

[0039] Figure 8 Another method for preparing a VCMA electrode capable of applying voltage to a free layer, as described in this invention;

[0040] in, Figure 8 Figure (A) shows the formation of a VCMA electrode film on the surface of an insulating film; Figure 8 Image B shows the etching of the excess electrodes at the top; Figure 8 The middle figure (C) shows the formation of the electrode covering insulating layer. Detailed Implementation

[0041] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] In the description of this invention, it should be noted that the terms "upper", "lower", "horizontal", "inner", "outer", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "forming" and "connecting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] The present invention will be further explained below with reference to specific embodiments.

[0045] Example 1

[0046] like Figure 1 As shown, the magnetic memory device of Embodiment 1 of the present invention includes a fixed layer 1, a tunnel insulating layer 2, a free layer 3, a free layer electrode 4, a VCMA electrode 5, an insulating layer film 6, a fixed layer electrode 7, and a wire 8.

[0047] Both the fixed layer 1 and the free layer 3 can be referred to as magnetic thin film structures (the magnetic thin film structure can be composed of one magnetic thin film layer, or multiple magnetic thin film layers, or one magnetic thin film layer and one non-magnetic thin film layer, or multiple magnetic thin film layers and non-magnetic thin film layers), and the insulating thin film 6 can be an oxide protective film.

[0048] The fixed layer 1 is also a magnetic thin film structure composed of a magnetic thin film and related auxiliary thin films (the magnetic thin film structure may be composed of a single magnetic thin film layer, or multiple magnetic thin film layers, or a single magnetic thin film layer and a single non-magnetic thin film layer, or multiple magnetic thin film layers and non-magnetic thin film layers).

[0049] The tunnel insulation layer 2 is disposed on the upper part of the fixed layer 1, and the tunnel insulation layer 2 is a non-magnetic thin film structure (which can be any one of a multilayer heterogeneous structure composed of different materials or a single structure composed of the same material); the non-magnetic thin film structure is a material other than magnetic; wherein, the tunnel insulation layer 2 is usually MgO, etc.

[0050] The free layer 3 is also a magnetic thin film structure composed of a magnetic thin film and related auxiliary thin films (the magnetic thin film structure may be composed of a single magnetic thin film layer, or multiple magnetic thin film layers, or a single magnetic thin film layer and a single non-magnetic thin film layer, or multiple magnetic thin film layers and a single non-magnetic thin film layer), which is located on top of the tunnel insulation layer 2.

[0051] The magnetic thin film structure in this embodiment 1 is a ferromagnetic thin film structure. This ferromagnetic thin film structure can consist of a single ferromagnetic thin film layer, multiple ferromagnetic thin film layers, a single ferromagnetic thin film layer combined with a single non-ferromagnetic thin film layer, or multiple ferromagnetic thin film layers combined with non-ferromagnetic thin film layers. The ferromagnetic thin film layer is typically a CoFeB alloy, etc. The magnetic material selected for this magnetic thin film structure is a strongly magnetic material with magnetic order; broadly speaking, it also includes weakly magnetic and antiferromagnetic materials from which their magnetic properties and magnetic effects can be utilized.

[0052] One end of the free layer electrode 4 is connected to the top of the free layer 3, and the other end extends outward.

[0053] The fixed layer 1, tunnel insulating layer 2, and free layer 3 are etched to form an MTJ device. The insulating thin film 6 (which can be a single layer or multiple thin films composed of different materials) surrounds the four sides of the MTJ device. The aforementioned MTJ device is a generalized MTJ device, referring to a structural element consisting of an insulating layer with a thickness of several nanometers or less sandwiched between two ferromagnetic thin films. Specifically, in this invention, the generalized MTJ device consists of two magnetic thin film structures and a non-magnetic thin film structure sandwiched between the two magnetic thin film structures. One of the magnetic thin film structures has a VCMA electrode on its side, which can be subjected to a voltage to control its magnetic anisotropy.

[0054] One end of the VCMA electrode 5 surrounds the outer layer of the insulating film 6 on the sides of the free layer 3, and the other end extends outward from the free layer 3 with a wire deposition hole 51 at the upper part of the extended end; the VCMA electrode 5 and the free layer electrode 4 have non-overlapping portions in both top and bottom view angles. The VCMA electrode 5 and the free layer electrode 4 must not be in contact.

[0055] Multiple conductive or non-conductive films of different compositions can be deposited between the insulating film 6 and the VCMA electrode 5. The VCMA electrode 5 can be a multilayer heterogeneous structure composed of different materials or a single structure composed of the same material. The VCMA electrode 5 can completely surround the outer surface of the insulating film, partially surround the outer surface of the insulating film, or partially contact the outer surface of the insulating film.

[0056] The fixed layer electrode 7 is used to apply voltage to the fixed layer 1. One end of the electrode is fixedly connected to the bottom of the fixed layer 1, and the other end extends outward at any angle from the fixed layer 1.

[0057] One end of the wire 8 is deposited in the wire deposition hole 51 at the other end of the VCMA electrode 5, and the other end is inserted into the insulating isolation layer.

[0058] like Figure 3 (A)- Figure 6 As shown in (T), the manufacturing method of the magnetic memory device in Embodiment 1 of the present invention first prepares a fixed layer electrode 7 located at the bottom, then prepares a fixed layer 1 on the prepared fixed layer electrode 7, prepares a tunnel insulating layer 2 on the prepared fixed layer 1, prepares a free layer 3 on the prepared tunnel insulating layer 2, then forms an MTJ device by etching the fixed layer 1, the tunnel insulating layer 2 and the free layer 3, then protects the MTJ device with an insulating film, then prepares VCMA electrodes 5 around the sides of the free layer 3 to apply voltage to it, then prepares a free layer electrode 4 at the top of the free layer 3, and finally prepares a wire 8 connecting the VCMA electrode 5 to the outside.

[0059] like Figure 1 As shown, in Embodiment 1 of the present invention, the fixed layer 1 of the magnetic memory device is at the bottom, and the free layer 3 is at the top; as Figure 2 As shown, in another embodiment of the magnetic memory device of the present invention, the free layer 3 is at the bottom and the fixed layer 1 is at the top. In this case, the structure and manufacturing method of the magnetic memory device of this embodiment can be adjusted accordingly in combination with the structure and manufacturing method of embodiment 1.

[0060] The manufacturing method of the magnetic memory device according to Embodiment 1 of the present invention specifically includes the following steps:

[0061] S11, such as Figure 3 As shown in (A), the bottom fixed layer electrode 7 is first prepared. On the fixed layer electrode 7 (which can also be the metal wire layer of the MOSFET or CMOS logic circuit that controls the MTJ switch below the MTJ), a multilayer thin film of the MTJ is prepared (i.e., a fixed layer 1 is prepared on the fixed layer electrode 7, a tunnel insulating layer 2 is prepared on the fixed layer 1, and a free layer 3 is prepared on the tunnel insulating layer 2).

[0062] S12, such as Figure 3 As shown in (B), the fixed layer 1, tunnel insulating layer 2 and free layer 3 are etched to form a vertical columnar (ideally cylindrical, but now semiconductor processes mostly produce frustum-shaped) MTJ device;

[0063] S13, such as Figure 3 As shown in (C), a thin insulating film 6 is deposited on the surface of the MTJ device;

[0064] S14, such as Figure 3 As shown in (D), an insulating isolation layer 91 is filled around the perimeter of the fixing layer 1; wherein, this insulating isolation layer 91 can be obtained by first depositing a thickness exceeding the height of the MTJ device, followed by CMP polishing, and then etching back. Figure 3 (D) flat interface;

[0065] S15, such as Figure 3 As shown in (E), a sacrificial layer 92 (e.g., Si3N4) is deposited on the periphery of the insulating film 6 located above the insulating isolation layer 91 until the thickness of the sacrificial layer 92 exceeds the height of the MTJ device and is then CMP-polished.

[0066] S16, as Figure 3 As shown in (F), the sacrificial layer 92 is etched back to the target thickness;

[0067] S17, such as Figure 4 As shown in (G), a photoresist layer 93 is deposited around the insulating film 6 on the upper part of the sacrificial layer 92 obtained in step S16 until the photoresist layer 93 exceeds the height of the MTJ device, and then the sacrificial layer 92 is processed by etching and other related techniques to form the desired pattern.

[0068] S18, such as Figure 4 As shown in (H), the excess sacrificial layer 92 is etched away;

[0069] S19, such as Figure 4 As shown in (I), an insulating isolation layer 94 is deposited around the sacrificial layer 92 obtained in step S18, and then the insulating isolation layer 94 is ground flat by CMP after it exceeds the height of the MTJ device.

[0070] S20, such as Figure 4 As shown in (J), a hole 921 is punched in the upper part of the sacrificial layer 92 obtained in step S18;

[0071] S21, such as Figure 4 As shown in (K), the sacrificial layer 92 obtained in step S20 is etched away;

[0072] S22, such as Figure 4 As shown in (L), a VCMA electrode 5 is deposited that can apply a voltage to the free layer 3; wherein, the VCMA electrode 5 here can be a multilayer heterostructure composed of different materials, or a single structure composed of the same material; here, another oxide insulating layer such as high-K oxide can be deposited before the VCMA electrode 5 is deposited; in addition, here, the previously deposited oxide insulating layer in contact with the MTJ device can be etched away before the VCMA electrode 5 is deposited, and then other insulating oxides are deposited, and then the VCMA electrode 5 is deposited.

[0073] S23, such as Figure 5 As shown in (M), the VCMA electrode 5 located in the hole 921 of step S20 is etched away.

[0074] S24, such as Figure 5 As shown in (N), the hole 921 obtained in step S20 is filled with an insulating isolation layer 94;

[0075] S25, such as Figure 5 As shown in (O), the insulating isolation layer 94 is ground smooth with CMP until the top of the free layer 3 is exposed;

[0076] S26, such as Figure 5 As shown in (P), a free layer electrode 4 is deposited on top of the free layer 3;

[0077] S27, such as Figure 5 As shown in (Q), the electrode material above the hole 921 in the aforementioned step S20 is etched away to facilitate the fabrication of the wire 8 used for the VCMA electrode 5 described later.

[0078] S28, such as Figure 5 As shown in (R), an insulating isolation layer 95 is then used to cover the periphery of the free layer electrode 4 and ground flat.

[0079] S29, such as Figure 6 As shown in (S), the insulating isolation layer 95 above the VCMA electrode 5 is perforated 951 to contact the VCMA electrode 5.

[0080] S30, such as Figure 6 As shown in (T), a VCMA electrode 5 is deposited in the hole 951 made in step (S29) and a wire 8 is connected to the outside.

[0081] like Figure 7 As shown in (AD), the method of depositing a VCMA electrode that can apply a voltage to a free layer (which can also be regarded as a single vertical columnar magnetic body) in step S22 above can also be carried out according to the following main steps:

[0082] S221, such as Figure 7 As shown in (A), a vertical columnar magnetic body 41 is prepared;

[0083] S222, such as Figure 7 As shown in (B), an insulating thin film 42 is deposited on the surface of the vertical columnar magnetic body 41;

[0084] S223, such as Figure 7 As shown in (C), a VCMA electrode 43 is directly deposited on the insulating thin film 42 to the target thickness;

[0085] S224, such as Figure 7As shown in (D), the VCMA electrode 43 in step S223 above is protected by an insulating isolation layer 44.

[0086] like Figure 8 As shown in (AC), after step S222 is performed, an electrode capable of applying voltage to the free layer (also known as a vertical columnar magnetic body) can be formed as follows:

[0087] S2221, such as Figure 8 As shown in (A), a VCMA electrode 54 capable of applying voltage to the vertical columnar magnetic body 53 is deposited on the surface of the insulating thin film 52.

[0088] S2222, such as Figure 8 As shown in (B), the VCMA electrodes 54 around the sides of the portion where no voltage needs to be applied are etched away.

[0089] S2223, such as Figure 8 As shown in (C), the above-mentioned VCMA electrode 54 is protected by an insulating isolation layer 55.

[0090] The present invention has a reasonable structural design and a relatively simple manufacturing process. The VCMA is generated from the side of the free layer and does not affect the tunnel insulation layer. Therefore, it can reduce magnetic anisotropy and help STT reduce the energy consumption of information writing, while also improving the durability of the tunnel insulation layer, making it suitable for promotion and application.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A magnetic memory device, characterized in that... The device includes a magnetic thin film structure, and electrodes are provided around the sides of the magnetic thin film structure to control its magnetic anisotropy by applying voltage to it. The device comprises two magnetic thin-film structures and a non-magnetic thin-film structure sandwiched between the two magnetic thin-film structures; one of the magnetic thin-film structures has a VCMA electrode on its side that can be subjected to a voltage to control its magnetic anisotropy; the VCMA electrode is any one of a multilayer heterostructure composed of different materials and a single structure composed of the same material. The method for preparing the VCMA electrode includes the following steps: Step (1.1): Deposit an insulating thin film on the surface of the MTJ device; Step (1.2): Deposit an insulating layer on the portion of the MTJ device where no voltage needs to be applied; Step (1.3): Deposit a sacrificial layer with a different etch selectivity than the insulating isolation layer in step (1.2) at the location where voltage needs to be applied to the MTJ device, and etch the sacrificial layer to form the desired pattern; Step (1.4): Deposit an insulating layer on top of the sacrificial layer obtained in step (1.3); Step (1.5): Deposit electrode material at one end of the magnetic thin film structure to which voltage needs to be applied, etch the electrode material, and then make it non-overlapping with the sacrificial layer etched in step (1.3) from a top view angle. Then cover it with an insulating isolation layer and grind it flat. Step (1.6): Etch and drill holes above the sacrificial layer that does not overlap with the electrode material in step (1.5) until the sacrificial layer is in contact, and then etch away the sacrificial layer; Step (1.7): Deposit a VCMA electrode at the location where the sacrificial layer was etched away in step (1.6); Step (1.8): Etch away the excess electrode material at the location of the hole in step (1.6) and deposit the wires connecting the electrode material to the outside world to finally form a VCMA electrode that can apply voltage to the magnetic thin film structure.

2. The magnetic memory device as described in claim 1, characterized in that... Both magnetic thin film structures are ferromagnetic thin film structures; an insulating thin film is provided around the sides of the structure composed of the two ferromagnetic thin film structures and the non-magnetic thin film structure; a VCMA electrode is provided on the outer side of the insulating thin film, which can apply a voltage to one of the ferromagnetic thin film structures to control the magnetic anisotropy.

3. The magnetic memory device as described in claim 2, characterized in that... The VCMA electrode is connected to the outer surface of the insulating film by any one of the following methods: completely surrounding the outer surface of the insulating film, partially surrounding the outer surface of the insulating film, or partially contacting the outer surface of the insulating film.

4. A method for manufacturing a magnetic memory device as described in any one of claims 1 to 3, characterized in that, First, a bottom electrode is prepared. Then, a magnetic thin film structure is prepared on the prepared bottom electrode. Next, a non-magnetic thin film structure is prepared on the prepared magnetic thin film structure. Then, another magnetic thin film structure is prepared on the non-magnetic thin film structure. Next, the two magnetic thin film structures and the non-magnetic thin film structure are etched to form an MTJ device. Then, an insulating layer film is prepared on the outer surface of the MTJ device. Then, VCMA electrodes are prepared around the sides of the magnetic thin film structure to which voltage needs to be applied. Finally, wires connecting the VCMA electrodes to the outside world are prepared.

5. The method for manufacturing the magnetic memory device as claimed in claim 4, characterized in that, The VCMA electrode is prepared according to the following steps: Step (2.1): Deposit an insulating thin film on the surface of the MTJ device; Step (2.2): Deposit the insulating layer and VCMA electrode using either of the following two methods: first depositing an insulating isolation layer on the part of the MTJ device where no voltage is required, and then depositing a VCMA electrode to the required thickness on the periphery of the magnetic thin film structure of the MTJ device where voltage is required; or first depositing a VCMA electrode to the required thickness on the periphery of the magnetic thin film structure of the MTJ device where voltage is required, and then depositing an insulating isolation layer on the part of the MTJ device where no voltage is required. Step (2.3): Protect the VCMA electrode obtained in step (2.2) by covering it with an insulating layer.

6. The method for manufacturing a magnetic memory device as described in claim 5, characterized in that: Step (2.2) involves depositing the VCMA electrode beyond the thickness of the MTJ device and then etching it back to the desired thickness.

7. The method for manufacturing a magnetic memory device as described in claim 4, characterized in that, The VCMA electrode is prepared according to the following steps: Step (3.1): Deposit an insulating thin film on the surface of the MTJ device; Step (3.2): Deposit a VCMA electrode on the outer surface of the insulating film; Step (3.3): Etch away the excess VCMA electrode so that the VCMA electrode surrounds the magnetic thin film structure to which voltage needs to be applied.

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