A terahertz ferroelectric synapse device and a preparation method thereof

Abstract

The application discloses a terahertz ferroelectric synapse device and a preparation method thereof. The terahertz ferroelectric synapse device comprises a substrate, a hafnium-based ferroelectric functional layer formed on the substrate and in a strip shape, and electrodes formed on both sides of the strip-shaped hafnium-based ferroelectric functional layer. The electrodes comprise a test area and a contact area, the contact area is in contact with the ferroelectric functional layer, the contact area is in a T-shaped structure, the extension direction of the flat top of the contact area is perpendicular to the extension direction of the ferroelectric functional layer, a terahertz excitation is applied to one side electrode, high-speed domain polarization inversion is realized, a controllable conductance modulation state is obtained, and the terahertz ferroelectric synapse device is used for neuromorphic computing.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, specifically to a terahertz ferroelectric neural synapse device and its fabrication method. Background Technology

[0002] In living organisms, neural synapses have a response time of 10ms and a response frequency of 100Hz, enabling efficient implementation of various neural computation and storage functions. Currently, existing electronic neural synapse devices can also achieve a response frequency of 100Hz, simulating the plasticity of neural synapses. To further improve computational efficiency, the development of biomimetic neural synapse devices with high-speed responses is urgently needed.

[0003] Recently, terahertz devices have attracted widespread attention and rapid development due to their advantages such as high signal-to-noise ratio in the time-domain spectrum, high instantaneous bandwidth, and matching with the vibrational and rotational energy levels of biological macromolecules. In particular, their high-frequency characteristics are of great significance for improving the response of electronic devices. Developing neural synaptic devices with terahertz responses will greatly improve the response sensitivity of devices and maximize computational efficiency.

[0004] Ferroelectric memories, as promising non-volatile memory devices, have important applications in the field of integrated circuits. Although traditional ferroelectric materials such as BiFeO3 and PbTiO3 have demonstrated their potential for use in biomimetic neural synapses, their development is limited by issues such as CMOS process compatibility and low response frequencies. The fabrication of doped hafnium-based ferroelectric thin films using physical vapor deposition (PVD) will overcome these limitations, showing potential for application in CMOS-compatible terahertz ferroelectric neural synapses. Summary of the Invention

[0005] This invention discloses a terahertz ferroelectric neural synapse device, comprising: a substrate; a hafnium-based ferroelectric functional layer formed on the substrate in an elongated strip shape; electrodes formed on both sides of the elongated hafnium-based ferroelectric functional layer, each electrode including a test area and a contact area, the contact area being in contact with the ferroelectric functional layer, the contact area being T-shaped, and the extension direction of its flat top being perpendicular to the extension direction of the ferroelectric functional layer; applying terahertz excitation to one side of the electrode to achieve high-speed domain polarization reversal, obtaining a controllable conductivity modulation state for neuromorphic computing.

[0006] In the terahertz ferroelectric synaptic device of the present invention, preferably, the spacing between the flat tops of the contact areas of the two electrodes is 10 nm to 70 nm.

[0007] In the terahertz ferroelectric neural synapse device of the present invention, preferably, the hafnium-based ferroelectric functional layer is Hf 0.5 Zr 0.5 O2, HfAlO x HfSiO x.

[0008] In the terahertz ferroelectric neural synapse device of the present invention, the length of the hafnium-based ferroelectric functional layer is preferably 50 μm to 200 μm, and the width is preferably 10 μm to 80 μm.

[0009] The present invention also discloses a method for fabricating a terahertz ferroelectric neural synapse device, comprising the following steps: forming an elongated hafnium-based ferroelectric functional layer on the substrate; forming electrodes on both sides of the elongated hafnium-based ferroelectric functional layer, wherein the electrodes include a test area and a contact area, the contact area is in contact with the ferroelectric functional layer, the contact area is T-shaped, and the extension direction of its flat top is perpendicular to the extension direction of the ferroelectric functional layer; applying terahertz excitation to one side electrode to achieve high-speed domain polarization reversal, thereby obtaining a controllable conductivity modulation state for neuromorphic computing.

[0010] In the method for fabricating the terahertz ferroelectric neural synapse device of the present invention, the preferred step of forming a strip-shaped hafnium-based ferroelectric functional layer specifically includes: spin-coating photoresist as a barrier layer at a rotation speed of 2000 rpm to 4000 rpm for 20 s to 120 s, baking at 90°C to 150°C for 30 s to 120 s, followed by ultraviolet exposure to define the growth region of the ferroelectric layer; growing a hafnium-based ferroelectric thin film with a thickness of 10 nm to 25 nm on a substrate using physical vapor deposition; removing the photoresist to obtain a strip-shaped hafnium-based ferroelectric thin film; and then performing a rapid thermal annealing process at 400°C to 600°C for 30 s to 120 s in a nitrogen atmosphere.

[0011] In the method for fabricating the terahertz ferroelectric neural synapse device of the present invention, preferably, the hafnium-based ferroelectric functional layer is Hf 0.5 Zr 0.5 O2, HfAlO x HfSiO x .

[0012] In the method for fabricating the terahertz ferroelectric neural synapse device of the present invention, the length of the hafnium-based ferroelectric functional layer is preferably 50 μm to 200 μm, and the width is preferably 10 μm to 80 μm.

[0013] In the method for fabricating the terahertz ferroelectric neural synapse device of the present invention, preferably, the spacing between the flat tops of the contact areas of the two electrodes is 10 nm to 70 nm.

[0014] Beneficial effects:

[0015] (1) Breakthrough in response speed of biological neural synapses and traditional neural synapse devices, by using terahertz response frequency to replace the traditional 100Hz response frequency, greatly improving the response speed of the device and enhancing the computing efficiency of the device.

[0016] (2) A terahertz device structure was designed and applied to ferroelectric nerve synapses, realizing cross-domain device integration, expanding the application field of terahertz devices, realizing the combination of storage and computing functions, and expanding the potential application scenarios of the devices.

[0017] (3) By using doped hafnium-based ferroelectric thin films deposited by physical vapor deposition to replace traditional ferroelectric layers such as PbTiO3, the CMOS compatibility of the device in integrated circuits is improved, and ferroelectric devices with high-frequency response are obtained, making the devices more likely to be applied to industrial-grade products. Attached Figure Description

[0018] Figure 1 This is a flowchart of the fabrication method for terahertz ferroelectric neural synaptic devices.

[0019] Figures 2-5 This is a flowchart of each stage of the fabrication process for terahertz ferroelectric neural synaptic devices.

[0020] Figure 6 This is a schematic diagram of the operation of a terahertz ferroelectric neural synapse device. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining this invention and are not intended to limit this invention. The described embodiments are merely some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] In the description of this invention, it should be noted that the terms "upper," "lower," "vertical," and "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] Furthermore, many specific details of the invention, such as the structure, materials, dimensions, processing techniques, and methods of the device, are described below to provide a clearer understanding of the invention. However, as those skilled in the art will understand, the invention may be implemented without adhering to these specific details. Unless specifically indicated below, various parts of the device may be made of materials known to those skilled in the art, or may employ materials with similar functionality developed in the future.

[0024] Figure 1 This is a flowchart illustrating the fabrication process of terahertz ferroelectric neural synaptic devices. (For example...) Figure 1 As shown, the fabrication method of the terahertz ferroelectric neural synapse device includes the following steps:

[0025] In step S1, a silicon wafer 100 with a silicon oxide layer 101 101 100 nm to 300 nm thick is prepared as a substrate for fabricating terahertz neural synapse devices. The substrate can also be glass, SiC, etc.

[0026] In step S2, AR-3510T photoresist is spin-coated onto the substrate as a barrier layer 102 at a rotation speed of 2000 rpm to 4000 rpm for 20 to 120 seconds. The substrate is then baked at 90°C to 150°C for 30 to 120 seconds, followed by UV exposure to define the growth region 103 of the ferroelectric layer. Figure 2 As shown.

[0027] Hafnium-based ferroelectric thin films 104 with a thickness of 10 nm to 25 nm were grown on a substrate using physical vapor deposition, such as... Figure 3 As shown. The preferred hafnium-based ferroelectric thin film is Hf. 0.5 Zr 0.5 O2 can also be Hf 0.5 Zr 0.5 O2, HfAlO x HfSiO x Equally doped hafnium-based ferroelectric thin films.

[0028] The AR-3510T photoresist was removed by ultrasonic removal with acetone to obtain elongated Hf strips with lengths ranging from 50 μm to 200 μm and widths ranging from 10 μm to 80 μm. 0.5 Zr 0.5 O2 thin film 105, such as Figure 4 As shown.

[0029] Subsequently, a rapid thermal annealing process was adopted, in which the annealing was carried out at a temperature of 400℃~600℃ for 30s~120s under a nitrogen atmosphere to obtain a functional layer with ferroelectric properties.

[0030] In step S3, electron beam lithography is used to create a long strip of Hf 0.5 Zr 0.5Electrodes Pt are fabricated on two widely spaced sides of an O2 thin film 105 to complete the fabrication of a terahertz ferroelectric synaptic device, such as... Figure 5 As shown. The two electrodes respectively include test areas 106, 106' and contact areas, wherein the contact area is connected to Hf 0.5 Zr 0.5 The O2 thin film is in contact with phase 105, and the contact area is T-shaped, including the main trunks 107 and 107' and the flat tops 108 and 108'. The extension direction of the main trunk is the same as that of the elongated Hf. 0.5 Zr 0.5 The O2 film 105 extends in a parallel direction and has overlapping regions; the extension direction of its flat top is parallel to that of the elongated Hf. 0.5 Zr 0.5 The O2 thin film 105 extends perpendicularly and overlaps each other. The spacing between the flat tops 108 and 108' of the two electrodes is preferably 10 nm to 70 nm. The electrode thickness is preferably 20 nm to 100 nm, and the electrode material is preferably Al, Au, Pt, Pd, Ti, Ni, etc.

[0031] like Figure 5 The terahertz ferroelectric neural synapse device shown includes a substrate; a hafnium-based ferroelectric functional layer 105 formed on the substrate in an elongated shape; and electrodes formed on two distant sides of the elongated hafnium-based ferroelectric functional layer. The two electrodes each include test areas 106 and 106' and contact areas. The contact areas are in contact with the hafnium-based ferroelectric functional layer 105 and are T-shaped, including main trunks 107 and 107' and flat tops 108 and 108'. The extension directions of the main trunks 108 and 108' are parallel to and overlap with the extension direction of the hafnium-based ferroelectric functional layer 105, while the extension direction of the flat tops 108 is perpendicular to and overlaps with the extension direction of the hafnium-based ferroelectric functional layer 105. Figure 6 As shown, terahertz excitation is applied to one electrode to achieve high-speed domain polarization reversal, thereby obtaining a controllable conductance modulation state for neuromorphic computing.

[0032] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A terahertz ferroelectric neural synapse device, characterized in that, include: Substrate; A hafnium-based ferroelectric functional layer is formed on the substrate in the form of a long strip; Electrodes are formed on both sides of the elongated hafnium-based ferroelectric functional layer. Each electrode includes a test area and a contact area. The contact area is in contact with the ferroelectric functional layer and is T-shaped, with its flat top extending perpendicular to the extension direction of the ferroelectric functional layer. By applying terahertz excitation to one electrode, high-speed domain polarization reversal is achieved, resulting in a controllable conductance modulation state for neuromorphic computing. The distance between the flat tops of the contact areas of the two electrodes is 10nm~70nm.

2. The terahertz ferroelectric neural synapse device according to claim 1, characterized in that, The hafnium-based ferroelectric functional layer is Hf 0.5 Zr 0.5 O2, HfAlO x or HfSiO x .

3. The terahertz ferroelectric neural synapse device according to claim 1, characterized in that, The length of the hafnium-based ferroelectric functional layer is 50μm~200μm, and the width is 10μm~80μm.

4. A method for fabricating a terahertz ferroelectric neural synapse device, characterized in that, Includes the following steps: A strip-shaped hafnium-based ferroelectric functional layer is formed on the substrate; Electrodes are formed on both sides of the elongated hafnium-based ferroelectric functional layer. Each electrode includes a test area and a contact area. The contact area is in contact with the ferroelectric functional layer and is T-shaped, with its flat top extending perpendicular to the extension direction of the ferroelectric functional layer. By applying terahertz excitation to one electrode, high-speed domain polarization reversal is achieved, resulting in a controllable conductance modulation state for neuromorphic computing. The distance between the flat tops of the contact areas of the two electrodes is 10nm~70nm.

5. The method for fabricating a terahertz ferroelectric neural synapse device according to claim 4, characterized in that, The steps for forming the elongated hafnium-based ferroelectric functional layer specifically include: Photoresist was spin-coated as a barrier layer at a speed of 2000 rpm to 4000 rpm for 20 to 120 seconds. The coating was then baked at 90°C to 150°C for 30 to 120 seconds, followed by UV exposure to define the growth region of the ferroelectric functional layer. Hafnium-based ferroelectric thin films with a thickness of 10 nm to 25 nm were grown on a substrate using physical vapor deposition. Remove the photoresist to obtain a strip-shaped hafnium-based ferroelectric functional layer; Subsequently, a rapid thermal annealing process was adopted, and the annealing was carried out at 400℃~600℃ for 30s~120s in a nitrogen atmosphere.

6. The method for fabricating a terahertz ferroelectric neural synapse device according to claim 4, characterized in that, The hafnium-based ferroelectric functional layer is Hf 0.5 Zr 0.5 O2, HfAlO x or HfSiO x .

7. The method for fabricating a terahertz ferroelectric neural synapse device according to claim 4, characterized in that, The length of the hafnium-based ferroelectric functional layer is 50μm~200μm, and the width is 10μm~80μm.

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