Magnetoelectric coupling device and neural network encryption and decryption method

Abstract

The present disclosure provides a magnetoelectric coupling device and a neural network encryption and decryption method. The magnetoelectric coupling device comprises: a substrate; a bottom electrode arranged on the surface of the substrate; a complex oxide layer provided on the surface of the bottom electrode away from the substrate; a magnetic PUF layer provided on the surface of the complex oxide layer away from the substrate; and a top electrode provided on the surface of the magnetic PUF layer away from the substrate. Compared with the prior art, in the magnetoelectric coupling device of the present application, a PUF source and a complex oxide are integrated into a same device, so that a hardware-level encryption and decryption function is realized, and encryption time and energy consumption are reduced; and by means of the coupling effect of the complex oxide and a magnetic domain wall, a reconfigurable PUF source is realized, so that a dynamically changing key can be generated by using the PUF source, thereby improving the flexibility and security of an encryption system and providing strong data protection and security.

Description

A magnetoelectric coupling device and a neural network encryption / decryption method Technical Field

[0001] This disclosure relates to the field of encryption and decryption technology, specifically to a magnetoelectric coupling device and a neural network encryption and decryption method. Background Technology

[0002] With the advancement of information technology, the speed of data generation is accelerating, and neural network learning and reasoning are increasingly being applied in daily life. At the same time, the generation, transfer, and processing of massive amounts of data are also placing higher demands on data encryption.

[0003] The development of the Internet of Things (IoT) and edge computing has led to an increasing amount of data and information being generated at data terminals. Therefore, highly integrated, fast, and low-power terminal encryption methods are becoming the main direction for future development. Existing terminal encryption methods are vulnerable to external attacks, and the complexity and cost of encryption are directly proportional, which is detrimental to edge applications.

[0004] Summary of the Invention

[0005] The purpose of this application is to provide a magnetoelectric coupling device and a neural network encryption / decryption method.

[0006] The first aspect of this application provides a magnetoelectric coupling device, comprising:

[0007] Substrate;

[0008] The bottom electrode is disposed on the surface of the substrate;

[0009] A complex oxide layer is disposed on the surface of the bottom electrode opposite to the substrate;

[0010] A magnetic physical random function (PUF) layer is disposed on the surface of the complex oxide layer opposite to the substrate.

[0011] The top electrode is disposed on the surface of the magnetic PUF layer opposite to the substrate.

[0012] In one possible implementation, the material of the complex oxide layer includes one or more of HfZrO, HfO2, BiTiO3, and BiFeO3.

[0013] In one possible implementation, the magnetic PUF layer includes:

[0014] A heavy metal layer is disposed on the surface of the complex oxide layer opposite to the substrate;

[0015] A magnetic domain layer is disposed on the surface of the heavy metal layer opposite to the substrate.

[0016] In one possible implementation, the material of the heavy metal layer includes one or more of W, Ta, Pt, and IrMn.

[0017] In one possible implementation, the material of the magnetic domain layer includes one or more of Co and CoFeB.

[0018] In one possible implementation, the materials of the bottom electrode and the top electrode include one or more of Ti / Au, SRO, and TiN.

[0019] In one possible implementation, the substrate material includes silicon dioxide.

[0020] A second aspect of this application provides a neural network encryption / decryption method, characterized in that, based on the magnetoelectric coupling device described in the first aspect above, the method includes:

[0021] During the key generation stage, a first voltage is applied to the magnetic PUF layer, and the key is extracted based on the physical properties of the magnetic domains of the magnetic PUF layer.

[0022] During the encryption phase, a second voltage is applied to the complex oxide layer, neural network weights are extracted based on the polarization position of the complex oxide layer, and the key generated by the magnetic PUF layer is XORed with the neural network weights stored in the complex oxide layer to encrypt the data and generate weight ciphertext. A third voltage is applied to the complex oxide layer to change the polarization position of the complex oxide layer so that the weight ciphertext is stored back in the complex oxide layer.

[0023] During the decryption phase, the weight ciphertext stored in the complex oxide layer is XORed with the key generated by the magnetic PUF layer to decrypt the neural network weights.

[0024] In one possible implementation, the method further includes:

[0025] A fourth voltage is applied to the magnetic PUF layer to change the physical properties of the magnetic domains of the magnetic PUF layer, thereby changing the key generated by the PUF layer.

[0026] The magnetoelectric coupling device provided in this application includes a substrate; a bottom electrode disposed on the surface of the substrate; a complex oxide layer disposed on the surface of the bottom electrode facing away from the substrate; a magnetic PUF layer disposed on the surface of the complex oxide layer facing away from the substrate; and a top electrode disposed on the surface of the magnetic PUF layer facing away from the substrate. Compared with the prior art, the magnetoelectric coupling device of this application integrates the PUF source and the complex oxide in the same device, realizing hardware-level encryption and decryption functions, saving encryption time and energy consumption; through the coupling effect between the complex oxide and the magnetic domain walls, a reconfigurable PUF source is realized, which can be used to generate dynamically changing keys, increasing the flexibility and security of the encryption system, and providing strong data protection and security. 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 disclosure. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0028] Figure 1 shows a perspective view of a magnetoelectric coupling device provided in an embodiment of this application;

[0029] Figure 2 shows a cross-sectional view along line Aa shown in Figure 1;

[0030] Figure 3 shows a schematic diagram of the ferroelectric properties of the complex oxide layer;

[0031] Figure 4 shows a schematic diagram of PUF characteristics based on magnetic domain walls;

[0032] Figure 5 shows a schematic diagram of the reconfigurable PUF characteristics;

[0033] Figure 6 illustrates the manufacturing process of a magnetoelectric coupling device provided in an embodiment of this application;

[0034] Figure 7 illustrates the encryption and storage process of neural network weights provided in an embodiment of this application;

[0035] Figure 8 illustrates the encryption and decryption schemes for complementary structure devices provided in embodiments of this application;

[0036] Figure 9 shows the truth table of the encryption scheme shown in Figure 8;

[0037] Figure 10 shows a schematic diagram of an array structure composed of magnetoelectric coupling device units. Detailed Implementation

[0038] Embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0039] The accompanying drawings illustrate various structural schematics according to embodiments of the present disclosure. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0040] In the context of this disclosure, when a layer / element is referred to as being "above" another layer / element, the layer / element may be directly above the other layer / element, or there may be an intermediate layer / element between them. Additionally, if a layer / element is "above" another layer / element in one orientation, then when the orientation is reversed, the layer / element may be "below" the other layer / element.

[0041] Please refer to Figures 1 and 2. Figure 1 shows a perspective view of a magnetoelectric coupling device provided in an embodiment of this application, and Figure 2 shows a cross-sectional view along line Aa shown in Figure 1.

[0042] As shown in Figures 1 and 2, the magnetoelectric coupling device of this application includes: a substrate 100, a bottom electrode 210, a complex oxide layer 300, a magnetic PUF layer 400, and a top electrode 220.

[0043] A bottom electrode 210 is disposed on the surface of the substrate 100; a complex oxide layer 300 is disposed on the surface of the bottom electrode 210 away from the substrate 100; a magnetic PUF layer 400 is disposed on the surface of the complex oxide layer 300 away from the substrate 100; and a top electrode 220 is disposed on the surface of the magnetic PUF layer 400 away from the substrate 100.

[0044] Specifically, the complex oxide layer 300 can be made of one or more complex oxides. In one embodiment, the material of the complex oxide layer includes one or more of zirconium hafnium oxide (HfZrO), hafnium dioxide (HfO2), bismuth titanate (BiTiO3), and bismuth ferrite (BiFeO3). The complex oxide layer serves as a storage medium for storing binary or multi-valued information and also as an interface control material for the magnetic PUF layer, working in conjunction with the PUF to maintain and update keys. Figure 3 shows a schematic diagram of the ferroelectric properties of the complex oxide layer 300 (P represents polarization intensity). Different polarization voltages drive the polarization positions, enabling the updating and storage of binary data.

[0045] Specifically, as shown in Figures 1 and 2, the PUF layer 400 includes a heavy metal layer 410 and a magnetic domain layer 420. The heavy metal layer 410 is disposed on the surface of the complex oxide layer 300 facing away from the substrate 100; the magnetic domain layer 420 is disposed on the surface of the heavy metal layer 410 facing away from the substrate 100.

[0046] In one embodiment, the material of the heavy metal layer 410 includes one or more heavy metal materials selected from tungsten (W), tantalum (Ta), platinum (Pt), and iridium-manganese alloy (IrMn).

[0047] In one embodiment, the material of the magnetic domain layer 420 includes one or more ferromagnetic materials selected from cobalt (Co) and cobalt iron boron (CoFeB).

[0048] The heavy metal layer 410 and the magnetic domain layer 420 form periodic magnetic domains or magnetic bubbles under the antisymmetric interaction and dipole interaction at the interface, which serve as the PUF source.

[0049] In heterostructures of magnetic PUF layers / complex oxide layers, the coupling effect at the interface and voltage-controlled anisotropy can regulate the magnitude of the coercivity and the strength of anisotropy of the ferromagnetic layer. Figure 4 shows that without an applied voltage, the Kerr signal of the device exhibits a butterfly-shaped KH curve under the influence of anisotropy, antisymmetric exchange, and dipole interactions. At this time, due to the different magnetization directions of the domain layers, the surface domains exhibit a random, periodic, maze-like morphology. Therefore, the above-mentioned domain physical characteristics can serve as a random PUF source, and the density of the domain structure can be controlled by different polarity voltages, with the brightness of the Kerr signal or the magnitude of the magnetoresistance signal forming a binary key. In Figure 4, I, II, III, and IV represent four states during the KH curve testing process, and the domain morphology in different states corresponds to the image on the right side of the figure.

[0050] This application utilizes the coupling effect between complex oxides and magnetic domain walls to generate a reconfigurable PUF source, making the key reconfigurable.

[0051] Figure 5 illustrates the reconfigurable PUF characteristics. When the voltage exceeds the threshold voltage for domain change, the labyrinthine domains transform into sparse dendritic domains. Random domains are restored by removing or reversing the voltage, thus resetting the PUF key. In Figure 5, I, II, III, and IV represent four states during the KH curve testing process, with the domain morphology in different states corresponding to the image on the right side of the figure.

[0052] In one embodiment, the materials of the bottom electrode and the top electrode include one or more conductive materials selected from titanium gold (Ti / Au), silicon-rich silicon oxide (SRO), and titanium nitride (TiN).

[0053] In one embodiment, the substrate is made of silicon dioxide.

[0054] Figure 6 shows a manufacturing process of the above-mentioned magnetoelectric coupling device provided in an embodiment of this application. As shown in Figure 6, a TiN bottom electrode is grown on a silicon dioxide wafer by ion beam sputtering. A complex oxide layer film is grown on the bottom electrode by atomic layer deposition (ALD) or pulsed laser deposition (PLD). A TiN top electrode is grown on the complex oxide layer by ion beam sputtering. The complex oxide ferroelectric and multiferroic properties are formed by annealing at 400-500°C for 30 seconds.

[0055] Then, the top electrode was removed by etching with a solution of H2O2:NH3OH = 1:1 for 15 min. Next, a magnetic PUF layer of heavy metal / ferromagnetic structure (such as Ta / CoFeB, W / CoFeB, Pt / CoFeB, Pt / Co) was grown on the complex oxide layer by magnetron sputtering. The device was then etched and isolated, and a top electrode of Ru, Pt, or Ti / Au was grown to realize the fabrication of the magnetoelectric coupling device.

[0056] In the above manufacturing process, annealing the top and bottom electrodes of the complex oxide film by ion beam sputtering can improve the ferroelectric and multiferroic properties of the complex oxide film; then removing the top electrode is to continue growing a PUF layer with a heavy metal / ferromagnetic structure on the complex oxide layer.

[0057] Based on the aforementioned magnetoelectric coupling device, this application embodiment also provides a neural network encryption / decryption method, specifically used for encrypting / decrypting neural network weights, the method comprising:

[0058] During the key generation stage, a first voltage is applied to the magnetic PUF layer, and the key is extracted based on the physical properties of the magnetic domains of the magnetic PUF layer.

[0059] During the encryption phase, a second voltage is applied to the complex oxide layer, neural network weights are extracted based on the polarization position of the complex oxide layer, and the key generated by the magnetic PUF layer is XORed with the neural network weights stored in the complex oxide layer to encrypt the data and generate weight ciphertext. A third voltage is applied to the complex oxide layer to change the polarization position of the complex oxide layer so that the weight ciphertext is stored back in the complex oxide layer.

[0060] During the decryption phase, the weight ciphertext stored in the complex oxide layer is XORed with the key generated by the magnetic PUF layer to decrypt the neural network weights.

[0061] Specifically, in the key generation stage, a random binary number is generated using the physical characteristics of the magnetic domains in the PUF layer. The magneto-optical Kerr signal of a specific region on the device surface is extracted using optical methods, or the magnetoresistance signal from different magnetic domain densities in the PUF layer is extracted as the key. When using optical extraction, due to the periodic structure of upward or downward magnetization of the magnetic domains, regions dominated by upward magnetization (bright areas) are treated as binary data "1", and vice versa as "0". In the encryption stage, the key generated by the PUF layer is XORed with the weights stored in the composite oxide layer for encryption. This allows encryption of the weight information stored in the composite oxide layer within the same device. The ciphertext, encrypted with the key generated by the PUF layer and the weights stored in the composite oxide layer, is stored in the composite oxide layer via a write operation. Decryption is performed by XORing the ciphertext stored in the composite oxide layer with the key generated by the PUF layer.

[0062] As shown in Figure 7, this application integrates the composite oxide layer as a neural network synapse and the PUF encryption structure into the same device. While reading out the neural network weights, the weights are encrypted. Furthermore, the decrypted information can be translated by generating plaintext through XOR operation between the PUF key and the ciphertext within the device, thus promoting the application of data encryption at the edge.

[0063] In one embodiment, the above neural network encryption / decryption method may further include:

[0064] A fourth voltage is applied to the magnetic PUF layer to change the physical properties of the magnetic domains of the magnetic PUF layer, thereby changing the key generated by the PUF layer.

[0065] This application can perform XOR operations for encryption and decryption using magnetic domain signals (key) and ferroelectric high / low resistance (information). Binary encryption and decryption can be performed by: XORing the key with the plaintext to obtain ciphertext, and then XORing the ciphertext with the key to obtain the plaintext.

[0066] In practice, as shown in Figure 8, a 0 / 1 key can be generated by adjusting the brightness or magnetoresistance of the magnetic domains in the complementary structure device. During encryption, the 0 / 1 of the key determines whether the device cell on the right side of the complementary structure is written with a low or high level. The level of the device on the left side is determined by the plaintext stored in the device. When the polarization is positive (negative), it represents that the synaptic storage value is 1 (0), and the voltage of the left synaptic device is high (low).

[0067] The complementary structure device shown in Figure 8 refers to a device on the left and right sides that generates keys with opposite values, where the key is either 1 or 0. S represents the plaintext write level, with high / low levels corresponding to 1 / 0.

[0068] Therefore, during the encryption process, if there is no potential difference between the left and right devices, the device resistance remains unchanged. If the potential on the left (right) side is higher than that on the right (left) side and is higher than the threshold voltage for flipping, the device on the left (right) side is set to 1 and the device on the right (left) side is set to 0, thus completing the encryption operation. The truth table is shown in Figure 9.

[0069] When reading or decrypting ciphertext, the direction of reading is determined by the key. When the key is 0 (1), the left (right) synaptic weight is read, which is the ciphertext weight. At the same time, the ciphertext can also be decrypted synchronously in the same way without increasing the circuit complexity.

[0070] This application also proposes an n*n array structure composed of magnetoelectric coupling device units. Figure 10 shows a 2*2 array structure, in which the dashed box contains an encryption unit containing two gate transistors, one transistor is connected to the heavy metal layer, the other transistor is connected to the top electrode, and the bottom electrode is grounded.

[0071] Array structure working principle: Two adjacent device units in the same row form a complementary structure device. The right device is selected by column transistor to be in high / low impedance state, corresponding to a key of 1 / 0; the left device is selected by row transistor to apply a high / low level, corresponding to plaintext of 1 / 0. The data is read by comparing the high and low impedance or the light and dark states of the two device units, corresponding to the electrical comparator and the optical Moke method, respectively.

[0072] The magnetoelectric coupling device and neural network encryption / decryption method provided in this application have the following beneficial effects:

[0073] (1) Highly secure data encryption: The key is generated by using a magnetoelectric coupling device and a physical random function (PUF) source to generate a dynamically changing key, which is combined with an encryption algorithm to reliably encrypt the data, providing strong data protection and security.

[0074] (2) Flexible and reconfigurable key generation: Through the coupling effect of complex oxides and magnetic domain walls, a reconfigurable PUF source is realized, which enables the key to be dynamically changed at runtime, increasing the flexibility and security of the encryption system.

[0075] (3) Hardware-level encryption and decryption function: The PUF and complex oxide neural network synapse are integrated into the same device, realizing hardware-level encryption and decryption function, saving encryption time and energy consumption.

[0076] (4) Simplified device structure and fabrication technology: The self-encrypting neural network hardware and system based on magnetoelectric coupling devices has a simple device structure, which facilitates large-scale fabrication and integrated application, providing a convenient solution.

[0077] (5) Improve the security of edge computing: By encrypting and decrypting the weights processed by the neural network, the confidentiality of the weight data is protected, thereby improving the security of edge computing.

[0078] (6) Promote the development of data encryption and edge security applications: This invention provides a powerful solution for the development of data encryption and edge security applications, and lays the hardware foundation for protecting sensitive data and improving the security of edge computing.

[0079] To achieve the same structure, those skilled in the art can also devise methods that are not entirely identical to those described above. Furthermore, although various embodiments have been described separately above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

[0080] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended 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. Such 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.

Claims

1. A magnetoelectric coupling device, characterized by, Comprising: a substrate; a bottom electrode disposed on a surface of the substrate; a complex oxide layer disposed on a surface of the bottom electrode facing away from the substrate; a magnetic PUF layer disposed on a surface of the complex oxide layer facing away from the substrate; a top electrode disposed on a surface of the magnetic PUF layer facing away from the substrate.

2. The magnetoelectric coupling device according to claim 1, wherein The material of the complex oxide layer comprises one or more of HfZrO, HfO2, BiTiO3, BiFeO3.

3. The magnetoelectric coupling device of claim 1, wherein, The magnetic PUF layer comprises: a heavy metal layer disposed on a surface of the complex oxide layer facing away from the substrate; a magnetic domain layer disposed on a surface of the heavy metal layer facing away from the substrate.

4. The magnetoelectric coupling device of claim 3, wherein, The material of the heavy metal layer comprises one or more of W, Ta, Pt, IrMn.

5. The magnetoelectric coupling device of claim 3, wherein, The material of the magnetic domain layer comprises one or more of Co, CoFeB.

6. The magnetoelectric coupling device of claim 1, wherein, The material of the bottom electrode and the top electrode comprises one or more of Ti / Au, SRO, TiN.

7. The magnetoelectric coupling device of claim 1, wherein, The material of the substrate comprises silicon dioxide.

8. A neural network encryption and decryption method, characterized by, The magnetoelectric coupling device according to any one of claims 1-7, the method comprising: in a key generation phase, applying a first voltage to the magnetic PUF layer to extract a key based on the magnetic domain physical characteristics of the magnetic PUF layer; in an encryption phase, applying a second voltage to the complex oxide layer to extract a neural network weight based on the polarization position of the complex oxide layer, performing an exclusive or operation between the key generated by the magnetic PUF layer and the neural network weight stored in the complex oxide layer to encrypt, and generating a weight ciphertext; applying a third voltage to the complex oxide layer to change the polarization position of the complex oxide layer to store the weight ciphertext back into the complex oxide layer; in a decryption phase, performing an exclusive or operation between the weight ciphertext stored in the complex oxide layer and the key generated by the magnetic PUF layer to decrypt, and obtaining the neural network weight. The method further comprises:

9. The neural network encryption and decryption method of claim 8, wherein, applying a fourth voltage to the magnetic PUF layer to change the magnetic domain physical characteristics of the magnetic PUF layer to change the key generated by the PUF layer. ​

Images