Nano-oscillator array and manufacturing method therefor, oscillator network and computing device
By controlling the membrane stack structure of the nano-oscillator array, the problems of in-plane current shunting and weak coupling strength are solved, realizing efficient computation and stable synchronization of the spin nano-oscillator array, which is suitable for high-speed, high-density computing and neuromorphic computing.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- INST OF MICROELECTRONICS CHINESE ACAD OF SCI LTD
- Filing Date
- 2024-11-20
- Publication Date
- 2026-05-15
AI Technical Summary
Existing spin-transfer torque nanooscillators suffer from in-plane current shunting and weak coupling strength, which affect their performance and computational capabilities.
By modulating the film stack structure of the nano-oscillator array, the cutoff position of the nanopillar etching is precisely controlled, forming a structure including a seed layer, a nanopillar common layer, and a nanopillar array, thereby improving the effective current density and achieving strong coupling between oscillators.
It improves the performance of nano-oscillators and the stability of computing systems, achieves synchronous behavior between oscillators, enhances computing power and robustness, and is compatible with CMOS integration technology, making it suitable for high-speed, high-density computing and neuromorphic computing.
Smart Images
Figure CN2024133256_15052026_PF_FP_ABST
Abstract
Description
Nanoscale oscillator arrays, their fabrication methods, oscillation networks, and computing devices Technical Field
[0001] This application relates to the field of oscillator technology, and in particular to a nano-oscillator array, its fabrication method, oscillation network, and computing device. Background Technology
[0002] Nanoscale oscillators are core components of microwave signal generators, widely used in various microwave systems such as communications, radar, electronic countermeasures, and test instruments. Among them, spin-torque nano-oscillators (STNOs) are microwave oscillators used in neuromorphic computing, wireless communication, and other fields to achieve wide-spectrum operating frequencies and high modulation rates. Due to their wide-spectrum operating frequency and high modulation rate properties, they have attracted widespread attention as an emerging type of nanoscale oscillator. Existing STNOs typically have a sandwich structure: a free layer / intermediate layer / fixed layer. The free layer and fixed layer are magnetic layers (ferromagnetic, antiferromagnetic, synthetic ferromagnetic, synthetic antiferromagnetic, etc.), while the intermediate layer is a non-magnetic metal layer or a non-magnetic insulating barrier layer. Current flows in from the nanoscale contact area between the electrodes and the oscillator, forms a polarized spin after passing through the polarized fixed layer, enters the free layer, and oscillates the magnetic moment of the free layer through spin-torque.
[0003] In existing technologies, for example, patent application CN110350284B discloses a simplified double-layer spin-torque nano-oscillator array with an insulating barrier layer. However, adjacent spin-torque nano-oscillators are coupled via dipole interaction, resulting in low coupling strength. Patent application CN111564686B discloses a simplified double-layer spin-torque nano-oscillator array with an insulating barrier layer. The nano-oscillator array shares a fixed substrate layer, but current injection onto the unified substrate synchronizes the coupling of the nano-oscillator array. However, the substrate area is large, resulting in low effective current density. Patent application CN 113097379 A discloses a magnetically coupled spin-torque nano-oscillator array. This array achieves spin-wave coupling between the free layers of adjacent nano-oscillators by depositing magnetic insulating material between them. However, this method requires the thickness of the magnetic insulating material to be approximately the same as the free layer and aligned with it, placing high demands on fabrication and thin-film deposition. The patent with publication number WO2017111688A1 discloses a magnetically coupled spin-transfer torque nano-oscillator array, but it belongs to the traditional nano-contact structure, which has the problem of current shunting in the cap layer and free layer, resulting in a reduction in effective current density.
[0004] It should be noted that the above statements are only used to provide background information related to this application and do not necessarily constitute prior art. Summary of the Invention
[0005] This application provides a nano-oscillator array based on spin-transfer torque, its fabrication method, oscillation network, and computing device, which can improve the shunting of in-plane current, significantly increase the density of effective current, and enhance the coupling strength of the nano-oscillator.
[0006] In a first aspect, embodiments of this application provide a nano-oscillator array based on spin-transfer torque, comprising a seed crystal layer and a nano-pillar common layer and a nano-pillar array formed sequentially along a direction away from the seed crystal layer; the nano-pillar common layer comprises at least a first magnetic thin film layer;
[0007] The nanopillar array includes multiple nanopillars arranged in an array, each nanopillar corresponding to a nano-spin oscillator; each nanopillar includes a second magnetic thin film layer and a capping layer arranged sequentially along the direction away from the seed crystal layer.
[0008] In one alternative embodiment, the first magnetic thin film layer includes a synthetic antiferromagnetic layer;
[0009] The second magnetic thin film layer includes a magnetic reference layer, a non-magnetic insulating barrier layer, and a magnetic free layer formed sequentially in a direction away from the first magnetic thin film layer.
[0010] In one optional embodiment, the synthetic antiferromagnetic layer comprises an antiferromagnetic layer, a magnetic layer, and a non-magnetic intermediate layer formed sequentially along a direction away from the seed crystal layer.
[0011] In one alternative embodiment, the first magnetic thin film layer includes a magnetic free layer and a non-magnetic insulating barrier layer.
[0012] The second magnetic thin film layer includes a magnetic reference layer and a synthetic antiferromagnetic layer formed sequentially in a direction away from the first magnetic thin film layer.
[0013] In one optional embodiment, the synthetic antiferromagnetic layer comprises a nonmagnetic intermediate layer, a magnetic layer, and an antiferromagnetic layer formed sequentially along a direction away from the seed crystal layer.
[0014] In one optional embodiment, the material of the synthetic antiferromagnetic layer includes any one of iridium-manganese alloy, manganese-platinum alloy, and manganese-selenium alloy; the material of the magnetic layer includes one or more of cobalt-iron alloy, cobalt-iron-boron alloy, metallic cobalt, and nickel-iron alloy; and the material of the non-magnetic intermediate layer includes any one of metallic ruthenium, metallic tungsten, and metallic copper.
[0015] In one optional embodiment, the materials of the magnetic free layer and the magnetic reference layer are both ferromagnetic, antiferromagnetic, subferromagnetic, synthetic antiferromagnetic, synthetic subferromagnetic, and synthetic ferromagnetic.
[0016] In one alternative embodiment, the material of the non-magnetic insulating barrier layer includes magnesium oxide or aluminum oxide.
[0017] In one alternative embodiment, the capping layer is made of one or more of tantalum, ruthenium, and platinum.
[0018] Secondly, embodiments of this application provide a method for fabricating a nano-oscillator array, used to fabricate the nano-oscillator array described in the first aspect, the method comprising:
[0019] A film stack and a hard mask of the nano-oscillator array are sequentially deposited on a substrate; the film stack is used to form the seed layer, the nanopillar common layer and the nanopillar array of the nano-oscillator array;
[0020] A first mask pattern is formed on the hard mask, and the film stack is first etched based on the hard mask having the first mask pattern, etching to the upper surface of the seed layer;
[0021] A second mask pattern is formed on the hard mask, and the film stack is etched a second time based on the hard mask having the second mask pattern, etching down to the shared layer of the nanopillars.
[0022] Thirdly, embodiments of this application provide an oscillation network, including a microwave conductor and the nano-oscillator array described in the first aspect; the microwave conductor generates a corresponding magnetic field based on an input microwave signal to be processed, and the magnetic field is coupled to the nano-oscillator array; the nano-oscillator array generates corresponding oscillation frequencies based on different input currents, and the nano-oscillators in the nano-oscillator array whose oscillation frequencies match the frequency of the microwave signal are phase-locked.
[0023] Fourthly, embodiments of this application provide a reservoir computing device based on a nano-oscillator array, comprising: an input layer and an output layer, and an oscillator reservoir composed of a nano-oscillator array as described in the first aspect, wherein the oscillator reservoir is disposed between the input layer and the output layer;
[0024] The input layer is used to inject the pulse signal of the signal to be processed into the oscillator reservoir; the nano-oscillators in the oscillator reservoir are coupled to each other, mapping the pulse signal of the signal to be processed to a higher-dimensional state space, generating high-dimensional feature data; the output layer is used to linearly output the high-dimensional feature data.
[0025] The technical solutions provided in this application embodiment have at least the following technical effects or advantages:
[0026] The spin-transfer torque-based nano-oscillator array provided in this application solves the problems of in-plane current shunting and weak coupling strength in traditional spin nano-oscillators by precisely controlling the cutoff position of the nanopillar etching through the film stack structure of the nano-oscillator array. This improves the performance of the spin-transfer torque nano-oscillator array, making its operation more reliable and stable. Simultaneously, the magnetically coupled spin-transfer torque nano-oscillator array achieves strong coupling between oscillators. Synchronization of the oscillators is achieved through spin waves, dipole interactions, and input phase-locked loops, thereby improving the computational power and robustness of the entire computing system based on this nano-oscillator array. Furthermore, the structure of this spin nano-oscillator array is compatible with existing CMOS (Complementary Metal-Oxide-Semiconductor) integration processes, possessing high controllability and scalability, facilitating large-scale implementation and fabrication. It also provides possibilities for the integrated application of high-speed, high-density random computing and neuromorphic computing, demonstrating broad application prospects and commercial value. Attached Figure Description
[0027] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:
[0028] Figure 1 is a schematic diagram of a nano-oscillator array based on spin-transfer torque provided in an embodiment of this application;
[0029] Figure 2 is a schematic diagram of the specific structure of a nano-oscillator array based on spin-transfer torque provided in an embodiment of this application;
[0030] Figure 3 is a schematic diagram of another specific structure of a nano-oscillator array based on spin-transfer torque provided in an embodiment of this application;
[0031] Figure 4 is a schematic flowchart of a method for fabricating a nano-oscillator array according to an embodiment of this application;
[0032] Figure 5 is a schematic flowchart of a method for fabricating a nano-oscillator array according to an embodiment of this application;
[0033] Figure 6 is a schematic diagram of an oscillation network provided in an embodiment of this application;
[0034] Figure 7 is a schematic diagram of a reservoir computing device based on a nano-oscillator array provided in this application. Detailed Implementation
[0035] Exemplary embodiments of this application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.
[0036] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application shall have the ordinary meaning as understood by one of ordinary skill in the art to which this application pertains.
[0037] In related technologies, spin-transfer torque nano-oscillators can be mainly divided into four categories: point-contact, nano-contact, nanopillar, and hybrid. Point-contact oscillators directly contact the oscillator via a metal probe, which presents reliability and damage issues. Nano-contact oscillators form nano-vias on an insulating protective layer using photolithography and etching techniques, and then deposit electrodes within these vias to form nano-point contacts. This results in in-plane current shunting, reducing the effective current density and increasing the threshold current. Nanopillar oscillators use photolithography and etching processes to etch the entire oscillator film stack into nanopillars, minimizing in-plane current shunting and increasing the effective current density. However, fabrication is challenging, and achieving coupling between completely isolated nanopillars is difficult. Hybrid oscillators combine nano-contact and nanopillar structures, reducing the threshold current by thinning the cap layer to form nano-contacts, but they still struggle to eliminate the effects of in-plane current shunting.
[0038] In order to eliminate or reduce in-plane current shunting and improve the coupling strength of the spin-transfer torque nano-oscillator, this embodiment studies the structure of the spin-transfer torque nano-oscillator. It is found that by adjusting the film stack structure of the spin-transfer torque nano-oscillator and precisely controlling the cutoff position of the nanopillar etching, the problems of in-plane current shunting and weak coupling strength in traditional spin-transfer torque nano-oscillators can be solved.
[0039] Based on the above findings, this application provides a nano-oscillator array based on spin-transfer torque, as shown in Figure 1. The nano-oscillator may include a seed layer and a shared nanopillar layer and a nanopillar array formed sequentially along a direction away from the seed layer. The shared nanopillar layer can be understood as a thin film layer shared by the nanopillar array, i.e., a cutoff layer (stopping at the upper surface of this layer) during nanopillar etching, or in other words, this layer does not participate in the formation of nanopillars, but supports the nanopillar array above it, just like the seed layer. The shared nanopillar layer may include at least a first magnetic thin film layer, allowing more current to flow into the shared nanopillar layer to reduce current loss in the plane of the non-magnetic thin film layer and increase the effective current density. The nanopillar array may include multiple nanopillars arranged in an array, each nanopillar corresponding to a nano-spin oscillator; each nanopillar may include a second magnetic thin film layer and a capping layer sequentially arranged along a direction away from the seed layer, the capping layer being used to protect the adjacent magnetic thin film layer.
[0040] The spin-transfer torque-based nano-oscillator array provided in this embodiment solves the problems of in-plane current shunting and weak coupling strength in traditional spin nano-oscillators by precisely controlling the cutoff position of the nanopillar etching through the film stack structure of the nano-oscillator array. This improves the performance of the spin-transfer torque nano-oscillator array, making its operation more reliable and stable. Simultaneously, the magnetically coupled spin-transfer torque nano-oscillator array achieves strong coupling between oscillators. Synchronization of the oscillators is achieved through spin waves, dipole interactions, and input phase-locked loops, thereby improving the computational power and robustness of the entire computing system based on this nano-oscillator array. Furthermore, the structure of this spin nano-oscillator array is compatible with existing CMOS (Complementary Metal-Oxide-Semiconductor) integration processes, possessing high controllability and scalability, facilitating large-scale implementation and fabrication. It also provides possibilities for the integrated application of high-speed, high-density random computing and neuromorphic computing, demonstrating broad application prospects and commercial value.
[0041] It should be noted that both the first magnetic thin film layer and the first magnetic thin film layer mentioned above can include a single thin film or multiple thin films. When the first magnetic thin film layer includes multiple thin films, non-magnetic thin film layers are allowed; when the first magnetic thin film layer includes a single thin film, that thin film is a magnetic thin film layer, and the shared layer of the nanopillar is allowed to also include other non-magnetic thin film layers. When the second magnetic thin film layer includes multiple thin films, non-magnetic thin film layers are allowed; when the second magnetic thin film layer includes a single thin film, that thin film is a magnetic thin film layer, and the nanopillar is allowed to also include other non-magnetic thin film layers.
[0042] The embodiments of this application will now be described in detail with reference to the accompanying drawings.
[0043] Example 1
[0044] Please refer to Figure 2, which is a schematic diagram of a nano-oscillator array based on spin-transfer torque provided in this application. As shown in Figure 2, the nano-oscillator array includes: a seed layer 101 (which can serve as a bottom electrode layer); a synthetic antiferromagnetic layer 102 formed on the seed layer 101; a magnetic reference layer 103 formed on the synthetic antiferromagnetic layer 102; a non-magnetic insulating barrier layer 104 formed on the magnetic reference layer 103; a magnetic free layer 105 formed on the non-magnetic insulating barrier layer 104; and a capping layer 106 formed on the magnetic free layer 105. During the etching process to form nanopillars, the etching can be stopped at the synthetic antiferromagnetic layer 102 using an endpoint detection method. Each nanopillar forms a nano-oscillator. The synthetic antiferromagnetic layer 102 is the first magnetic thin film layer mentioned above; the magnetic reference layer 103, the non-magnetic insulating barrier layer 104, and the magnetic free layer 105 can be collectively referred to as the second magnetic thin film layer.
[0045] In this embodiment, each nanopillar forms a nanospin oscillator in the spin-transfer torque nanooscillator array, and the nanospin oscillators share a common synthetic antiferromagnetic layer 102. Adjacent nanospin oscillators are coupled together through dipole interaction, input phase-locking, and other methods to form a coupled nanooscillator array, which improves the coupling strength of the array. During the etching process to form the nanopillars, an endpoint detection method can be used to ensure that the etching stops at the synthetic antiferromagnetic layer, further reducing the shunting of in-plane current in the capping layer 106 and the magnetic free layer 105, and increasing the effective current density of the nanooscillators.
[0046] It should be noted that each nano oscillator can be configured with an independent input current or can share an input current. Adjacent nano oscillators can be current-locked and have a gain current output.
[0047] Specifically, the synthetic antiferromagnetic layer 102 may include an antiferromagnetic layer 111, a magnetic layer 112, and a non-magnetic intermediate layer 113 sequentially formed along a direction away from the seed layer 101. Thus, by using the non-magnetic intermediate layer 113 to separate the magnetic layer 112 and the magnetic reference layer 103, independent input currents can be configured, or a shared input current can be used. Based on this shared synthetic antiferromagnetic layer 102, a coupled array of nano-oscillators can be formed through input phase-locking, dipole interaction, or other methods, and adjacent nano-oscillators can be phase-locked to increase the output current.
[0048] Among them, the antiferromagnetic layer 111 can be any one of IrMn, Mn3Pt, Mn3Se, etc., the magnetic layer 112 can be one or more of CoFe, CoFeB, Co, NiFe, etc., and the non-magnetic intermediate layer 113 can be any one of Ru, W, Cu, etc.
[0049] The materials of the magnetic free layer 105 and the magnetic reference layer 103 can both be any of the following: ferromagnetic, antiferromagnetic, subferromagnetic, synthetic antiferromagnetic, synthetic subferromagnetic, and synthetic ferromagnetic materials. The material of the non-magnetic insulating barrier layer 104 can include any of the following: MgO, AlOx, etc.
[0050] The capping layer 106 can be used to protect the magnetic free layer 105, and its material can include one or more metals such as tantalum (Ta), ruthenium (Ru), and platinum (Pt).
[0051] Example 2
[0052] Please refer to Figure 3, which is a schematic diagram of another nano-oscillator array based on spin-transfer torque provided in this application. As shown in Figure 3, the nano-oscillator array includes: a seed layer 201 (which can serve as a bottom electrode layer); a magnetic free layer 202 formed on the seed layer 201; a non-magnetic insulating barrier layer 203 formed on the magnetic free layer 202; a magnetic reference layer 204 formed on the non-magnetic insulating barrier layer 203; a synthetic antiferromagnetic layer 205 formed on the magnetic reference layer 204; and a capping layer 206 formed on the synthetic antiferromagnetic layer 205. During the etching process to form nanopillars, the etching can be stopped at the non-magnetic insulating barrier layer 203 using an endpoint detection method. One nanopillar forms one nano-oscillator. The magnetic free layer 202 and the non-magnetic insulating barrier layer 203 can be collectively referred to as the first magnetic thin film layer; the magnetic reference layer 204 and the synthetic antiferromagnetic layer 205 can be collectively referred to as the second magnetic thin film layer.
[0053] In the spin-transfer torque nano-oscillator array provided in this embodiment, each nanopillar forms a nano-spin oscillator. Multiple nano-oscillators share a non-magnetic insulating barrier layer 203 and a magnetic free layer 202, and can form a coupled nano-oscillator array through spin waves 206, input phase-locking, dipole interactions, etc. Adjacent nano-spin oscillators are coupled together through dipole interactions, input phase-locking, etc., to form a coupled nano-oscillator array, which improves the coupling strength of the nano-oscillator array. During the etching to form the nanopillars, the etching is stopped at the non-magnetic insulating barrier layer 203, which further reduces the shunting of the in-plane current in the capping layer 206 and improves the effective current density of the nano-oscillator.
[0054] It should be noted that each nano oscillator can be configured with an independent input current or can share an input current. Adjacent nano oscillators can be current-locked and have a gain current output.
[0055] Specifically, the synthetic antiferromagnetic layer 205 may include a non-magnetic intermediate layer 211, a magnetic layer 212, and an antiferromagnetic layer 213 sequentially formed along a direction away from the seed layer 201. In this way, the non-magnetic intermediate layer 211 separates the magnetic reference layer 204 and the magnetic layer 212 of the synthetic antiferromagnetic layer 205, and can be configured with independent input currents or share input currents.
[0056] Among them, the antiferromagnetic layer 213 can be any one of IrMn, Mn3Pt, Mn3Se, etc., the magnetic layer 212 can be one or more of CoFe, CoFeB, Co, NiFe, etc., and the non-magnetic intermediate layer 211 can be any one of Ru, W, Cu, etc.
[0057] The materials of the magnetic free layer 202 and the magnetic reference layer 204 can both be any of the following: ferromagnetic, antiferromagnetic, subferromagnetic, synthetic antiferromagnetic, synthetic subferromagnetic, and synthetic ferromagnetic materials. The material of the non-magnetic insulating barrier layer 203 can include any of MgO and AlOx.
[0058] The capping layer 206 can be used to protect the magnetic free layer 202, and its material can include one or more metals such as tantalum (Ta), ruthenium (Ru), and platinum (Pt).
[0059] Example 3
[0060] Please refer to Figure 4, which is a schematic flowchart of a method for fabricating a nano-oscillator array provided in this application. This fabrication method can be used to fabricate the nano-oscillator arrays provided in Example 1 or Example 2. As shown in Figure 4, the fabrication method may include the following steps:
[0061] Step S1: Sequentially deposit a film stack of nano-oscillator array and a hard mask on the substrate; the film stack is used to form the seed layer, the nanopillar common layer and the nanopillar array of nano-oscillator array;
[0062] Step S2: A first mask pattern is formed on the hard mask, and the film stack is first etched based on the hard mask with the first mask pattern, etching to the upper surface of the seed layer;
[0063] Step S3: Form a second mask pattern on the hard mask, and perform a second etching on the film stack based on the hard mask with the second mask pattern, etching down to the nanopillar common layer.
[0064] It is understood that the structure of the film stack of the above-mentioned nano-oscillator array can be any of the embodiments in Example 1 or Example 2, and this embodiment does not specifically limit it.
[0065] The method for preparing the nano-oscillator array provided in this embodiment can prepare the nano-oscillator array provided in Embodiment 1 or Embodiment 2, and can at least achieve the beneficial effects of the nano-oscillator array provided in Embodiment 1 or Embodiment 2, which will not be elaborated here.
[0066] It should be noted that steps S1-S3 described above do not constitute a limitation on this embodiment. After the second etching is completed, as shown in Figure 5, an insulating protective layer can be grown in situ, and after insulation protection, the sample can be chemically and mechanically polished to remove the remaining hard mask. Subsequently, a third mask pattern can be formed on the nano-oscillator film stack, and the insulating protective layer can be etched a third time using the third mask pattern to open the vias in the bottom electrode layer; then, the electrode can be grown using a vapor deposition process.
[0067] Example 4
[0068] Please refer to Figure 6, which is a schematic diagram of the structure of an oscillation network provided in this application. As shown in Figure 6, the oscillation network may include a microwave conductor and a nano-oscillator array provided in Embodiment 1 or Embodiment 2. The microwave conductor generates a corresponding magnetic field based on the input microwave signal to be processed, and the magnetic field is coupled to the nano-oscillator array. The nano-oscillator array generates a corresponding oscillation frequency based on different input currents, and the nano-oscillators in the nano-oscillator array whose oscillation frequency matches the frequency of the microwave signal are phase-locked.
[0069] The oscillation network provided in this embodiment includes the spin-transfer torque nano-oscillator array provided in Embodiment 1 or Embodiment 2, and can at least achieve the beneficial effects of the nano-oscillator array provided in Embodiment 1 or Embodiment 2, which will not be elaborated further here. It can also perform tasks such as voice and image recognition.
[0070] In one specific embodiment, each row of nano-oscillators shares the same input current, and the nano-oscillators in the same row have phase-locked gain outputs. Different rows of spin nano-oscillators have different input currents and different oscillation frequencies. Image, voice, and other recognition signals are encoded into microwave signals f. A +f B The input microwave conductor 401 generates an Oersted field (i.e., a magnetic field), which is coupled to a spin nano-oscillator array. The spin nano-oscillator, whose oscillation frequency is the same as the input microwave signal frequency, will be phase-locked with the input, thus enhancing the output; that is, the oscillation network has identified a specific input.
[0071] In another embodiment, each nano-oscillator has an independent current, and the output of the nano-spin oscillator is enhanced by being phase-locked with the microwave signal frequency, i.e., the oscillation network identifies a specific input.
[0072] Example 5
[0073] Please refer to Figure 7, which is a schematic diagram of a reservoir computing device based on a nano-oscillator array provided in this application. As shown in Figure 7, the reservoir computing device may include: an input layer and an output layer, and an oscillator reservoir composed of a nano-oscillator array as provided in Embodiment 1 or Embodiment 2. The oscillator reservoir is disposed between the input layer and the output layer. The input layer is used to inject the pulse signal of the signal to be processed into the oscillator reservoir. Each nano-oscillator in the oscillator reservoir is coupled to each other, mapping the pulse signal of the signal to be processed to a higher-dimensional state space to generate high-dimensional feature data. The output layer is used to linearly output the high-dimensional feature data.
[0074] The input layer samples and encodes voice, image, and video signals into pulse sequences of a certain amplitude. This pulse sequence is then input into a reservoir based on a spin-transfer torque nano-oscillator array. The oscillators in the reservoir's array are coupled through spin waves, dipole interactions, and input phase-locking. The reservoir responds to each input, continuously adjusting the linear weights between the reservoir and the output layer to produce the correct output.
[0075] The reservoir computing device provided in this embodiment includes a reservoir composed of a spin-transfer torque nano-oscillator array as provided in Embodiment 1 or Embodiment 2. It can at least achieve the beneficial effects of the nano-oscillator array provided in Embodiment 1 or Embodiment 2, which will not be elaborated further here. It can also perform efficient and accurate processing and calculation of voice, image, and video signals, thereby improving the computing power and robustness of the reservoir computing device in fields such as neuromorphic computing and communication systems.
[0076] The preferred embodiments of the present invention have been described in detail above. It should be noted that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without any creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.
[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application 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 therein. 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 this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.
Claims
1. A nano-oscillator array based on spin-transfer torque, characterized in that, It includes a seed crystal layer and a shared layer of nanopillars and a nanopillar array formed sequentially along a direction away from the seed crystal layer; the shared layer of nanopillars includes at least a first magnetic thin film layer; The nanopillar array includes multiple nanopillars arranged in an array, each nanopillar corresponding to a nano-spin oscillator; each nanopillar includes a second magnetic thin film layer and a capping layer arranged sequentially along the direction away from the seed crystal layer.
2. The nano-oscillator array as described in claim 1, characterized in that, The first magnetic thin film layer includes a synthetic antiferromagnetic layer; The second magnetic thin film layer includes a magnetic reference layer, a non-magnetic insulating barrier layer, and a magnetic free layer formed sequentially in a direction away from the first magnetic thin film layer.
3. The nano-oscillator array as described in claim 2, characterized in that, The synthetic antiferromagnetic layer comprises an antiferromagnetic layer, a magnetic layer, and a non-magnetic intermediate layer formed sequentially along a direction away from the seed crystal layer.
4. The nano-oscillator array as described in claim 1, characterized in that, The first magnetic thin film layer includes a magnetic free layer and a non-magnetic insulating barrier layer; The second magnetic thin film layer includes a magnetic reference layer and a synthetic antiferromagnetic layer formed sequentially in a direction away from the first magnetic thin film layer.
5. The nano-oscillator array as described in claim 4, characterized in that, The synthetic antiferromagnetic layer comprises a non-magnetic intermediate layer, a magnetic layer, and an antiferromagnetic layer formed sequentially along a direction away from the seed crystal layer.
6. The nano-oscillator array as described in claim 3 or 5, characterized in that, The antiferromagnetic layer is made of any one of iridium-manganese alloy, manganese-platinum alloy, and manganese-selenium alloy; the magnetic layer is made of one or more of cobalt-iron alloy, cobalt-iron-boron alloy, metallic cobalt, and nickel-iron alloy; and the non-magnetic intermediate layer is made of any one of metallic ruthenium, metallic tungsten, and metallic copper.
7. The nano-oscillator array as described in claim 3 or 5, characterized in that, The materials of the magnetic free layer and the magnetic reference layer are both ferromagnetic, antiferromagnetic, subferromagnetic, synthetic antiferromagnetic, synthetic subferromagnetic, and synthetic ferromagnetic.
8. The nano-oscillator array as described in claim 3 or 5, characterized in that, The material of the non-magnetic insulating barrier layer includes magnesium oxide or aluminum oxide.
9. The nano-oscillator array according to any one of claims 1-5, characterized in that, The capping layer is made of one or more of the following metals: tantalum, ruthenium, and platinum.
10. A method for fabricating a nano-oscillator array, characterized in that, The method for preparing the nano-oscillator array according to any one of claims 1-9 comprises: A film stack and a hard mask of the nano-oscillator array are sequentially deposited on a substrate; the film stack is used to form the seed layer, the nanopillar common layer and the nanopillar array of the nano-oscillator array; A first mask pattern is formed on the hard mask, and the film stack is first etched based on the hard mask having the first mask pattern, etching to the upper surface of the seed layer; A second mask pattern is formed on the hard mask, and the film stack is etched a second time based on the hard mask having the second mask pattern, etching down to the shared layer of the nanopillars.
11. An oscillating network, characterized in that, Includes microwave conductors and the nano-oscillator array as described in any one of claims 1-9; The microwave conductor generates a corresponding magnetic field based on the input microwave signal to be processed, and the magnetic field is coupled to the nano-oscillator array. The nano-oscillator array generates corresponding oscillation frequencies based on different input currents, and the nano-oscillators in the array whose oscillation frequencies match the frequency of the microwave signal are phase-locked.
12. A reservoir computing device based on a nano-oscillator array, characterized in that, include: An input layer and an output layer, and an oscillator reservoir formed by a nano-oscillator array as described in any one of claims 1-9, wherein the oscillator reservoir is disposed between the input layer and the output layer; The input layer is used to inject the pulse signal of the signal to be processed into the oscillator-based reservoir; The nano-oscillators in the oscillator reservoir are coupled to each other, mapping the pulse signal of the information to be processed to a higher-dimensional state space, generating high-dimensional feature data; The output layer is used to convert the... High-dimensional feature data is output linearly.