Spin-orbit moment magnetic memory and preparation method thereof
By forming the first heavy metal layer and the second heavy metal layer in the spin orbit moment providing layer of SOT-MRAM and depositing in a pure argon environment, the problems of reduced SOT efficiency and difficulty in MTJ etching caused by excessive SOT layer thickness are solved, and efficient SOT efficiency and yield improvement are achieved.
Patent Information
- Application Number
- CN202311835701.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-27
- Publication Date
- 2025-06-27
AI Technical Summary
After the SOT layer thickness is greater than a certain process-defined thickness, the existing SOT-MRAM is easily converted into a low-resistance α phase, resulting in a decrease in SOT efficiency and a difficult MTJ etching, which easily causes inhomogeneity and circuit breakage between device bits.
The first and second heavy metal layers are formed in the spin orbital moment providing layer, and by deposition in a pure argon environment, the resistivity of the two layers is ensured to be different, and separated by the interpolation, increasing the overall thickness to reduce the difficulty of MTJ etching.
While ensuring high SOT efficiency of the SOT layer, it reduces the difficulty of MTJ etching, improves the yield of the device, and reduces the write power consumption.
Smart Images
Figure CN120224693A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of memories, and particularly to a spin-orbit torque magnetic memory and a preparation method thereof. Background Art
[0002] The spin-orbit torque magnetic random access memory (SOT-MRAM) is a new generation of magnetic memory, which has the advantages of non-volatility, fast write speed, and low write power consumption. The core components of the SOT-MRAM are the spin-orbit torque providing layer (SOT layer) and the magnetic tunnel junction (MTJ). When a charge current is applied to the SOT layer, due to the spin-orbit coupling effect, the charge current is converted into a spin current, generating a spin-orbit torque, which causes the magnetization reversal of the magnetic free layer in the MTJ, thereby realizing the writing of information.
[0003] Currently, heavy metals are used as the SOT layer in SOT-MRAM. Taking β-phase W (β-W) as an example, the reasons for using β-W as the SOT layer are that on the one hand, β-W has a relatively high charge current-spin current conversion efficiency (SOT efficiency), and its SOT efficiency is positively correlated with the resistivity of the SOT layer; on the other hand, the preparation process of the β-W SOT layer is compatible with the existing memory production line.
[0004] However, usually, the W thin film can only maintain the high-resistance β-phase when the thickness is very thin. When the thickness is greater than a certain process-defined thickness, it will turn into the low-resistance α-phase, and α-W has a low SOT efficiency, which will reduce the SOT efficiency of the device. Among them, the process-defined thickness varies with different processes and will not be specifically described here.
[0005] Therefore, in order to ensure that W has a high SOT efficiency, the thickness of the SOT layer is usually 5 nm or even less. And the thin SOT layer poses a great challenge to the MTJ etching process, which requires that the etching of the MTJ needs to stop precisely on the SOT layer. If the SOT layer is over-etched, it may cause non-uniformity between device bits, and even break the SOT layer, causing an open circuit and reducing the device yield.
[0006] Therefore, how to ensure the SOT efficiency of the SOT layer while reducing the difficulty of MTJ etching has become an urgent problem to be solved at present. Summary of the Invention
[0007] To solve the above problems, the spin-orbit torque magnetic memory and the preparation method thereof provided by the present invention can reduce the difficulty of MTJ etching while ensuring the SOT efficiency of the SOT layer by forming a first heavy metal layer and a second heavy metal layer in the spin-orbit torque providing layer.
[0008] In a first aspect, the present invention provides a spin-orbit torque magnetic memory, which includes a spin-orbit torque providing layer and a magnetic tunnel junction stacked from bottom to top;
[0009] The spin-orbit torque providing layer includes a first heavy metal layer, an interlayer, and a second heavy metal layer stacked from bottom to top. The materials of the first heavy metal layer and the second heavy metal layer are both heavy metal materials in the β-phase. The resistivity of the first heavy metal layer is different from that of the second heavy metal layer. The material of the interlayer is different from the materials of the first heavy metal layer and the second heavy metal layer, and the thickness of the interlayer is less than the spin diffusion length of the interlayer.
[0010] Optionally, the resistivity of the first heavy metal layer is greater than that of the second heavy metal layer.
[0011] Optionally, the resistivity of the first heavy metal layer is less than that of the second heavy metal layer.
[0012] Optionally, the constituent elements of the materials of the first heavy metal layer and the second heavy metal layer include at least one of W, Ta, and Pt.
[0013] Optionally, the thickness range of the first heavy metal layer is 1 nm to 8 nm, and the thickness range of the second heavy metal layer is 1 nm to 8 nm.
[0014] Optionally, the material of the interlayer includes at least one of Ta, Pt, Hf, Mo, Cu, Au, Ru, NiO, CuN, and two-dimensional materials.
[0015] Optionally, the thickness of the interlayer is less than or equal to 2 nm.
[0016] In a second aspect, the present invention provides a spin-orbit torque magnetic memory, which includes a spin-orbit torque providing layer and a magnetic tunnel junction stacked from bottom to top;
[0017] The spin-orbit torque providing layer includes a first heavy metal layer and a second heavy metal layer stacked from bottom to top. The materials of the first heavy metal layer and the second heavy metal layer are both heavy metal materials in the β-phase. The first heavy metal layer and the second heavy metal layer are formed in a pure argon environment.
[0018] Optionally, the resistivity of the first heavy metal layer is greater than that of the second heavy metal layer.
[0019] Optionally, the resistivity of the first heavy metal layer is less than that of the second heavy metal layer.
[0020] Optionally, the materials of the first heavy metal layer and the second heavy metal layer include at least one of W, Ta, and Pt. The thickness range of the first heavy metal layer is 1 nm to 8 nm, and the thickness range of the second heavy metal layer is 1 nm to 8 nm.
[0021] In a third aspect, the present invention provides a method for manufacturing a spin-orbit torque magnetic memory, which is used to manufacture any spin-orbit torque magnetic memory in the first aspect.
[0022] Optionally, the method includes: forming a first heavy metal layer and a second heavy metal layer in a pure argon environment.
[0023] In a fourth aspect, the present invention provides a method for manufacturing a spin-orbit torque magnetic memory, which is used to manufacture any spin-orbit torque magnetic memory in the second aspect.
[0024] The spin-orbit torque magnetic memory and its manufacturing method provided by the embodiments of the present invention form a first heavy metal layer and a second heavy metal layer in the spin-orbit torque providing layer, so that both the first heavy metal layer and the second heavy metal layer can be manufactured below the corresponding process limit thickness. In this way, the overall thickness of the spin-orbit torque providing layer is increased, thereby reducing the manufacturing difficulty of the MTJ. By limiting the resistivity of the first heavy metal layer and the second heavy metal layer, the heavy metal layer with a high resistivity can provide a higher SOT efficiency, and the heavy metal layer with a low resistivity can reduce the shunt effect. While overall improving the SOT efficiency of the spin-orbit torque magnetic memory, the write power consumption of the spin-orbit torque magnetic memory can also be reduced overall. Description of the Drawings
[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0026] Figure 1 It is a schematic structural diagram of a spin-orbit torque magnetic memory according to an embodiment of the present application;
[0027] Figure 2 It is a schematic diagram showing the change of the resistivity of heavy metals deposited under different process conditions with thickness;
[0028] Figure 3 It is a schematic structural diagram of a spin-orbit torque magnetic memory according to an embodiment of the present application.
[0029] Reference Signs:
[0030] 1. Spin-orbit torque providing layer; 11. First heavy metal layer; 12. Second heavy metal layer; 13. Interlayer; 2. Magnetic tunnel junction. Detailed Embodiments
[0031] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. Embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.
[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the description of the present application in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present application.
[0033] Spatial relationship terms such as "under", "below", "lower", "beneath", "above", "upper", etc. can be used herein to describe the relationship of one element or feature shown in the drawings with other elements or features. It should be understood that, in addition to the orientation shown in the drawings, spatial relationship terms also include different orientations of the devices in use and operation. For example, if the device in the drawings is flipped, the element or feature described as "under other elements" or "beneath it" or "under it" will be oriented "above" the other elements or features. Thus, the exemplary terms "under" and "below" can include both the upper and lower orientations. In addition, the device may also include additional orientations (such as rotating 90 degrees or other orientations), and the spatial descriptors used herein are accordingly interpreted.
[0034] It should be noted that when an element is referred to as "fixedly connected" to another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. On the contrary, when an element is referred to as being "directly on" another element, there is no intermediate element. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are only for illustrative purposes.
[0035] As used herein, the singular forms "a", "an" and "the" may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms "comprise / include" or "have" etc. specify the presence of the stated features, wholes, steps, operations, components, parts or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.
[0036] In a first aspect, an embodiment of the present invention provides a spin-orbit torque magnetic memory, see Figure 1, the spin-orbit torque magnetic memory includes a spin-orbit torque providing layer 1 and a magnetic tunnel junction 2 stacked from bottom to top.
[0037] The cross-sectional shape of the magnetic tunnel junction 2 includes, but is not limited to, circular, elliptical or rectangular. The magnetic tunnel junction is stacked from bottom to top with a free layer, a barrier layer, a reference layer, a pinned layer and a protective layer. Among them, the materials of the free layer and the reference layer can be at least one of Co (cobalt), Fe (iron), Ni (nickel), B (boron) and Pt (platinum), and a multilayer film formed by combining the above elements or alloys with at least one of Co, Fe, Ni, Pt, Pd (palladium), Mo (molybdenum), W (tungsten), Ir (iridium), Ta (tantalum), Ru (ruthenium), Nb (niobium) and Hf (hafnium). The material of the barrier layer can be at least one of MgO (magnesium oxide), MgAl2O4 (magnesium aluminate), Al2O3 (aluminum oxide), Gd2O3 (gadolinium oxide), HfO2 (hafnium oxide), and this embodiment does not make specific limitations on this.
[0038] The spin-orbit torque providing layer 1 includes a first heavy metal layer 11, an interlayer 13 and a second heavy metal layer 12 stacked from bottom to top. The materials of the first heavy metal layer 11 and the second heavy metal layer 12 are both heavy metal materials in the β phase. The resistivity of the first heavy metal layer 11 is different from that of the second heavy metal layer 12. The material of the interlayer 13 is different from the materials of the first heavy metal layer 11 and the second heavy metal layer 12, and the thickness of the interlayer 13 is less than the spin diffusion length of the interlayer 13. By setting the interlayer 13, the formation of the first heavy metal layer 11 and the second heavy metal layer 12 can be facilitated, and by limiting the thickness of the interlayer 13, the influence of spin current transmission can be reduced.
[0039] Among them, the heavy metal material constituent elements include at least one of W, Ta and Pt; the thickness range of the first heavy metal layer 11 is 1 nm to 8 nm, such as 5 nm; the thickness range of the second heavy metal layer 12 is 1 nm to 8 nm, such as 5 nm.
[0040] The material constituent elements of the interlayer 13 include at least one of Ta, Pt, Hf, Mo, Cu, Au, Ru, NiO, CuN and two-dimensional materials. The thickness of the interlayer 13 is less than or equal to 2 nm, and this embodiment does not make specific limitations on this.
[0041] In this embodiment, the resistivity of the first heavy metal layer 11 is greater than that of the second heavy metal layer 12 and greater than the resistivity of the free layer in the magnetic tunnel junction 2. The resistivity of the interlayer 13 is less than that of the first heavy metal layer 11 and is relatively close to the resistivity of the second heavy metal layer 12. In this way, the charge current and spin current in the first heavy metal layer 11 can more easily be transmitted through the interlayer 13 into the second heavy metal layer 12, thereby flipping the magnetic moment of the free layer to complete the writing of information. The resistivity difference between the second heavy metal layer 12 and the free layer is relatively small, weakening the current shunting effect; at the same time, the relatively small resistivity of the second heavy metal layer 12 reduces the overall resistance of the spin-orbit torque providing layer 1, reducing the power consumption of information writing.
[0042] By forming the interlayer 13 between the first heavy metal layer 11 and the second heavy metal layer 12 to separate the first heavy metal layer 11 and the second heavy metal, it is convenient for the formation of the second heavy metal layer 12. At the same time, the uniformity of the resistivity of the first heavy metal layer 11 and the second heavy metal layer 12 is ensured, further ensuring the yield of the spin-orbit torque magnetic memory.
[0043] In this embodiment, the thickness range of the first heavy metal layer 11 is preferably 2.5 nm to 5 nm, and the thickness range of the second heavy metal layer 12 is preferably 2.5 nm to 5 nm. This embodiment does not make specific limitations; the materials of the first heavy metal and the second heavy metal are both β-phase W.
[0044] It should be noted that under the same process conditions, the resistivity of the heavy metal decreases with the increase of the thickness. And under different process conditions, the heavy metals deposited with the same thickness have different resistivities. For details, see Figure 2 , where process conditions 1 to 3 are for depositing the same heavy metal by magnetron sputtering, and the deposition is carried out in an environment where only argon is introduced and no other doping gases are introduced, that is, in a pure argon environment. Specifically, the three process conditions can be different argon concentrations and / or different pressures in the environment. This embodiment will not elaborate too much on this.
[0045] The spin-orbit torque magnetic memory provided in this embodiment forms a first heavy metal layer, an interlayer, and a second heavy metal layer in the spin-orbit torque providing layer, enabling the first heavy metal layer and the second heavy metal layer to be prepared below the corresponding process limit thickness. In this way, the overall thickness of the spin-orbit torque providing layer is increased, thereby reducing the preparation difficulty of the MTJ. By limiting the resistivities of the first heavy metal layer and the second heavy metal layer, the heavy metal layer with a high resistivity can provide a higher SOT efficiency, and the heavy metal layer with a low resistivity can reduce the shunting effect. While overall improving the SOT efficiency of the spin-orbit torque magnetic memory, the writing power consumption of the spin-orbit torque magnetic memory can also be reduced as a whole.
[0046] In a second aspect, an embodiment of the present invention provides a spin-orbit torque magnetic memory. Refer to Figure 1 , the difference between this spin-orbit torque magnetic memory and the spin-orbit torque magnetic memory in the first aspect is that: the resistivity of the first heavy metal layer 11 is less than that of the second heavy metal layer 12, the resistivity of the interlayer 13 is less than that of the second heavy metal layer 12, and is relatively close to the resistivity of the first heavy metal layer 11; the thickness range of the first heavy metal layer 11 is preferably 2.5 nm to 5 nm, and the thickness range of the second heavy metal layer 12 is preferably 2.5 nm to 5 nm.
[0047] In the spin-orbit torque magnetic memory provided in this embodiment, the resistivity of the first heavy metal layer 11 is lower than that of the second heavy metal layer 12. After a current is passed through the spin-orbit torque providing layer 1, the charge current mainly flows in the first heavy metal layer 11. The first heavy metal layer 11 converts the charge current into a spin current, and the second heavy metal layer 12 more efficiently converts the charge current in the layer into a spin current. The second heavy metal layer 12 blocks the influence of the charge current in the first heavy metal layer 11 from diverting into the free layer, reducing the information writing power consumption.
[0048] In a third aspect, an embodiment of the present invention provides a spin-orbit torque magnetic memory. Refer to Figure 3 , this spin-orbit torque magnetic memory is basically the same as the spin-orbit torque magnetic memory in the first aspect, the difference being that: the spin-orbit torque providing layer 1 is only formed by stacking the first heavy metal layer 11 and the second heavy metal layer 12 from bottom to top, and it does not include the interlayer 13.
[0049] It should be noted that in this embodiment, the first heavy metal layer 11 and the second heavy metal layer 12 are formed in a pure argon environment. By defining that the first heavy metal layer 11 and the second heavy metal layer 12 are formed in a pure argon environment without doping, the resistivity of each part of the first heavy metal layer 11 and the second heavy metal layer 12 is made more uniform, which is beneficial to improving the yield of the device.
[0050] In a fourth aspect, an embodiment of the present invention provides a spin-orbit torque magnetic memory. Refer to Figure 3 , this spin-orbit torque magnetic memory is basically the same as the spin-orbit torque magnetic memory in the second aspect, the difference being that: the spin-orbit torque providing layer 1 is only formed by stacking the first heavy metal layer and the second heavy metal layer from bottom to top, and it does not include the interlayer 13.
[0051] It should be noted that in this embodiment, the first heavy metal layer 11 and the second heavy metal layer 12 are formed in a pure argon environment. By defining that the first heavy metal layer 11 and the second heavy metal layer 12 are formed in a pure argon environment without doping, the resistivity of each part of the first heavy metal layer 11 and the second heavy metal layer 12 is made more uniform, which is beneficial to improving the yield of the device.
[0052] Fifth aspect, an embodiment of the present invention provides a method for manufacturing a spin-orbit torque magnetic memory, which is used to manufacture the spin-orbit torque magnetic memory in any of the above aspects.
[0053] Further, the method includes: forming a first heavy metal layer 11 and a second heavy metal layer 12 in a pure argon environment.
[0054] It should be noted that taking the spin-orbit torque magnetic memory in the second aspect as an example, when etching the MTJ after depositing the spin-orbit torque providing layer 1, since the total thickness of the spin-orbit torque providing layer 1 is thicker than that of the existing single-layer SOT layer, the second heavy metal layer 12 outside the MTJ region can be partially etched or etched, thereby improving the etching yield of the MTJ part. The interlayer 13 and the first heavy metal layer 11 below the second heavy metal layer 12 that are etched or partially etched are retained. Since the resistivity of the first heavy metal layer 11 and the interlayer 13 is less than that of the second heavy metal layer 12, the power consumption during information writing by energization will not be too high, and the thermal effect in the regions of the interlayer 13 and the first heavy metal layer 11 below the second heavy metal layer 12 that are partially etched or etched is not significant, and will not reduce the performance of the magnetic memory device.
[0055] In the method for manufacturing the spin-orbit torque magnetic memory provided in this embodiment, no other gas doping is required except argon during the deposition of the spin-orbit torque providing layer 1, the operation is simple, and the reliability is high.
[0056] In the description of this specification, the description referring to terms such as "some embodiments", "other embodiments", "ideal embodiments", etc. means that the specific features, structures, materials or features described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.
[0057] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.
[0058] The above-described embodiments only represent several implementation manners of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.
Claims
1. A spin-orbit torque magnetic memory, characterized in that, The spin-orbit torque magnetic memory includes a spin-orbit torque providing layer and a magnetic tunnel junction stacked from bottom to top; The spin-orbit torque providing layer includes a first heavy metal layer, an interlayer, and a second heavy metal layer stacked from bottom to top. The materials of the first heavy metal layer and the second heavy metal layer are both heavy metal materials in the β phase. The resistivity of the first heavy metal layer is different from the resistivity of the second heavy metal layer. The material of the interlayer is different from the materials of the first heavy metal layer and the second heavy metal layer, and the thickness of the interlayer is less than the spin diffusion length of the interlayer.
2. The spin-orbit torque magnetic memory according to claim 1, characterized in that, The resistivity of the first heavy metal layer is greater than the resistivity of the second heavy metal layer.
3. The spin-orbit torque magnetic memory according to claim 1, wherein The resistivity of the first heavy metal layer is less than the resistivity of the second heavy metal layer.
4. The spin-orbit torque magnetic memory according to claim 1, wherein The constituent elements of the materials of the first heavy metal layer and the second heavy metal layer include at least one of W, Ta, and Pt.
5. The spin-orbit torque magnetic memory according to claim 1, characterized in that, The thickness range of the first heavy metal layer is 1 nm to 8 nm, and the thickness range of the second heavy metal layer is 1 nm to 8 nm.
6. The spin-orbit torque magnetic memory according to claim 1, characterized in that, The material of the interlayer includes at least one of Ta, Pt, Hf, Mo, Cu, Au, Ru, NiO, CuN, and two-dimensional materials.
7. The spin-orbit torque magnetic memory according to claim 1, wherein The thickness of the interlayer is less than or equal to 2 nm.
8. A spin-orbit torque magnetic memory, characterized in that, The spin-orbit torque magnetic memory includes a spin-orbit torque providing layer and a magnetic tunnel junction stacked from bottom to top; The spin-orbit torque providing layer includes a first heavy metal layer and a second heavy metal layer stacked from bottom to top. The materials of the first heavy metal layer and the second heavy metal layer are both heavy metal materials in the β phase, and the first heavy metal layer and the second heavy metal layer are formed in a pure argon environment.
9. The spin-orbit torque magnetic memory according to claim 8, wherein The resistivity of the first heavy metal layer is greater than the resistivity of the second heavy metal layer.
10. The spin-orbit torque magnetic memory according to claim 8, wherein The resistivity of the first heavy metal layer is less than the resistivity of the second heavy metal layer.
11. The spin-orbit torque magnetic memory according to any one of claims 8 to 10, characterized in that, The constituent elements of the materials of the first heavy metal layer and the second heavy metal layer include at least one of W, Ta, and Pt. The thickness range of the first heavy metal layer is 1 nm to 8 nm, and the thickness range of the second heavy metal layer is 1 nm to 8 nm.
12. A method for preparing a spin-orbit torque magnetic memory, characterized in that, The method is used to prepare the spin-orbit torque magnetic memory according to any one of claims 1 to 7.
13. The method according to claim 12, wherein The method includes: forming the first heavy metal layer and the second heavy metal layer in a pure argon environment.
14. A method for preparing a spin-orbit torque magnetic memory, characterized in that, The method is used to prepare the spin-orbit torque magnetic memory according to any one of claims 8 to 11.