CN109802035B - Memristor-based nerve synapse bionic device and preparation method thereof - Google Patents

Abstract

The invention discloses a memristor-based nerve synapse bionic device and a preparation method thereof. The bionic device comprises: the flexible upper electrode layer is positioned above the copper nanoparticle doped silicon oxynitride thin film layer; the flexible lower electrode layer comprises a first flexible substrate and a first silver nanowire transparent electrode positioned above the first flexible substrate; the flexible upper electrode layer comprises a second flexible substrate and a second silver nanowire transparent electrode positioned below the second flexible substrate; the lower electrode layer and the upper electrode layer are both prepared by spraying silver nanowire ink on a flexible substrate to form a silver nanowire wet film and performing constant heat treatment in a sealed container; the copper nanoparticle doped silicon oxynitride film layer is prepared by adding a copper sheet on a silicon nitride target material by adopting a radio frequency reaction magnetron co-sputtering method and introducing oxygen. The nerve synapse bionic device provided by the invention can efficiently simulate nerve synapse functions and has short-term plasticity.

Description

A memristor-based neurosynaptic bionic device and its preparation method

technical field

The invention relates to the technical field of synaptic bionic devices, in particular to a memristor-based neurosynaptic bionic device and a preparation method.

Background technique

The basic unit of the brain to process information is the neuron, and the synapse is the key part where neurons contact each other and transmit information. Neurotransmitters are released into the synaptic cleft through the presynaptic membrane, and act on the receptors on the post-synaptic membrane, so that the potential change of the post-synaptic membrane causes the next neuron to excite or inhibit. Synapses change under the stimulation of electrical signals, so that the connection strength between neurons is strengthened or weakened, that is, synapses have plasticity. The memory and learning functions of biological systems are based on the precise control of the flow of ions through neurons and synapses. Synaptic function simulation is the key to realize bionic circuits and develop human-like computers.

Currently, the closest device to the function of a synapse is a memristor. The memristor can record the changes of the voltage applied and the charge flowing according to its resistance state at any time. The plastic response to electrical stimulation was similar. Before the emergence of memristive devices, the hardware implementation of artificial neural network synapses required very large-scale integrated circuits, and the density of artificial neural networks was far less than that of biological neural networks, thus restricting artificial neural networks from simulating complex brain functions. The emergence of memristors solves this problem. Under the action of an electric field, the resistance of the device can slowly change from low (high) resistance to high (low) resistance, and the process of increasing and decreasing conductivity corresponds to the synaptic Enhance and inhibit processes.

Although this characteristic of the memristor is similar to the synaptic weight change characteristic of the synapse under the stimulation of bioelectrical signals, it still cannot precisely control the flow of conductive particles of the memristor, and the resistive functional layer of the conventional memristor mainly It is composed of materials such as titanium dioxide, zinc oxide, perovskite manganese oxide, amorphous silicon, and chalcogenides. Through chemical structure design and synthesis, the control space for the electrical properties of the device is small. Therefore, the existing memristors have low efficiency in simulating synaptic functions and do not have short-term plasticity, which restricts the further development of this device as a synaptic bionic device.

Contents of the invention

Based on this, it is necessary to provide a memristor-based neurosynaptic bionic device and its preparation method, so as to accurately control the aggregation state structure and resistive function layer structure of the conductive particles in the material system through the electric field, and effectively control the migration of the conductive particles. , to regulate the resistance state of the material, which can efficiently simulate the function of synapses and has short-term plasticity.

To achieve the above object, the present invention provides the following scheme:

A memristor-based neurosynaptic biomimetic device, comprising: a flexible lower electrode layer, a copper nanoparticle-doped silicon oxynitride film layer deposited on the flexible lower electrode layer, and a nitrogen-doped copper nanoparticle layer located on the flexible lower electrode layer. A flexible upper electrode layer above the silicon oxide film layer;

The flexible lower electrode layer includes a first flexible substrate and a first silver nanowire transparent electrode positioned above the first flexible substrate; the flexible upper electrode layer includes a second flexible substrate and a silver nanowire transparent electrode positioned below the second flexible substrate. The second silver nanowire transparent electrode;

Both the lower electrode layer and the upper electrode layer are formed by spraying silver nanowire ink on the flexible substrate by electrostatic spraying method to form a silver nanowire wet film, and are made by constant heat treatment in a sealed container;

The copper nanoparticle-doped silicon oxynitride thin film layer is made by adding copper flakes on the silicon nitride target material by radio-frequency reactive magnetron co-sputtering and injecting oxygen into it.

Optionally, the doping amount of copper in the copper nanoparticle-doped silicon oxynitride thin film layer is 5%-23%.

Optionally, the flexible substrate is a PI film.

Optionally, the thickness of the flexible lower electrode layer and the flexible upper electrode layer are both 50-350 nm.

Optionally, the copper nanoparticle-doped silicon oxynitride film layer has a thickness of 20-200 nm.

The present invention also provides a method for preparing a memristor-based neurosynaptic bionic device, the method comprising:

The upper surface of the first flexible substrate is sprayed with silver nanowire ink by electrostatic spraying method to form a silver nanowire wet film, and the first flexible substrate with the silver nanowire wet film on the surface is subjected to constant heat treatment in a sealed container to obtain a flexible lower electrode layer;

With the flexible lower electrode layer as the substrate, the copper sheet is added on the silicon nitride target material by radio frequency reactive magnetron co-sputtering method, and the distance between the silicon nitride target material and the flexible lower electrode layer is controlled to be 30 ~ After adjusting the vacuum degree to 2×10 ^-4 ~ 2.5×10 ^-4 Pa, fill in argon to sputter the silicon nitride target for 8 ~ 12min, and then pass in oxygen to make the ratio of oxygen to argon 10: 10 sccm, continue to sputter the silicon nitride target material for 30-60 min to form a copper nanoparticle-doped silicon oxynitride film layer;

Depositing the copper nanoparticle-doped silicon oxynitride thin film layer on the flexible lower electrode layer substrate, and performing annealing treatment;

The upper surface of the second flexible substrate is sprayed with silver nanowire ink by electrostatic spraying method to form a silver nanowire wet film, and the second flexible substrate with the silver nanowire wet film on the surface is subjected to constant heat treatment in a sealed container to obtain a flexible upper electrode layer;

The flexible upper electrode layer is vertically reversed and then stacked on the copper nanoparticle-doped silicon oxynitride thin film layer.

Optionally, during the constant heat treatment, the temperature is controlled to be 120-220° C., and the duration is controlled to be 30-120 min.

Optionally, the temperature of the flexible lower electrode layer in the radio frequency reactive magnetron co-sputtering method is controlled between 25°C and 280°C.

Optionally, the radio frequency power is controlled to be 100W after the oxygen is introduced.

Optionally, the area ratio of the copper sheet to the gallium nitride target is 1%-10%, and the annealing temperature is 300-350°C.

Compared with prior art, the beneficial effect of the present invention is:

The invention provides a memristor-based neural synapse bionic device and a preparation method. The neurosynaptic bionic device comprises: a flexible lower electrode layer, a copper nanoparticle-doped silicon oxynitride film layer deposited on the flexible lower electrode layer, and a flexible upper electrode layer located above the copper nanoparticle-doped silicon oxynitride film layer . In the present invention, the copper nanoparticle-doped silicon oxynitride thin film layer is used as the resistive switching functional layer. Under the action of current, it can imitate the characteristics of biological synapses, and its high and low resistance states change slowly and the range is stable; multiple stable resistance states appear and It has good retention characteristics, and when the electrical pulse stimulation is repeatedly applied, the resistance can repeat the high-low resistance transition; it realizes the precise control of the aggregated structure of the conductive particles of the material system and the structure of the resistive functional layer through the electric field, and effectively controls the conduction. The migration of particles is used to regulate the resistance state of the material, which can efficiently simulate the function of synapses and has short-term plasticity; the manufacturing process is simple, the performance is stable, and it has broad application prospects.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some of the present invention. Embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without paying creative labor.

FIG. 1 is a schematic structural diagram of a memristor-based neurosynaptic bionic device according to an embodiment of the present invention;

FIG. 2 is a state diagram of a nanoparticle-doped silicon oxynitride thin film layer in two states of power-on and power-off according to an embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

FIG. 1 is a schematic structural diagram of a memristor-based synaptic bionic device according to an embodiment of the present invention.

Referring to Fig. 1, the neurosynaptic biomimetic device based on the memristor of the embodiment includes: a flexible lower electrode layer 3, a copper nanoparticle-doped silicon oxynitride film layer 2 deposited on the flexible lower electrode layer 3 and a The flexible upper electrode layer 1 above the copper nanoparticle-doped silicon oxynitride film layer 2; the flexible upper electrode layer 1 and the flexible lower electrode layer 3 are silver nanowire transparent electrode layers; the flexible lower electrode Layer 3 includes a first flexible substrate 31 and a first silver nanowire transparent electrode 32 above the first flexible substrate 31; the flexible upper electrode layer 1 includes a second flexible substrate 11 and a first flexible electrode located on the second flexible substrate 11. The second silver nanowire transparent electrode 12 below; the flexible lower electrode layer 3 and the flexible upper electrode layer 1 are all sprayed with silver nanowire ink on the flexible substrate by electrostatic spraying method, and the droplets randomly occupy and stack each other A silver nanowire wet film is formed, and it is made by constant heat treatment in a sealed container; the copper nanoparticle-doped silicon oxynitride thin film layer 2 is made by adding copper flakes on a silicon nitride target by radio frequency reactive magnetron co-sputtering method made by adding oxygen.

As an optional implementation manner, the doping amount of copper in the copper nanoparticle-doped silicon oxynitride thin film layer 2 is 5%-23%.

As an optional implementation, the flexible substrate is a PI film.

As an optional implementation manner, the flexible lower electrode layer 3 and the flexible upper electrode layer 1 both have a thickness of 50-350 nm.

As an optional implementation manner, the copper nanoparticle-doped silicon oxynitride film layer 2 has a thickness of 20-200 nm.

As an optional implementation manner, the diameter of the silver nanowires in the silver nanowire ink is 5-150 nm, and the length of the silver nanowires is 25-500 nm.

The principle of the neurosynaptic bionic device based on the memristor in this embodiment is: after the copper nanoparticle-doped silicon oxynitride thin film layer is energized, under the action of an electric field, the copper nanoparticle-doped silicon nitride oxide thin film layer is arranged neatly The position of the copper nanoparticles begins to break up, gradually diffuses and passes through the film to form clusters of conductive filaments, which can transmit current from the flexible lower electrode layer to the flexible upper electrode layer; after the power is turned off, the temperature drops, and the copper nanoparticles Will be rearranged neatly, reflected in the change of device resistance under the action of an electric field, as shown in Figure 2, wherein part (a) in Figure 2 is a state diagram of the nanoparticle-doped silicon oxynitride film layer in the power-off state, Part (b) in FIG. 2 is a state diagram of the nanoparticle-doped silicon oxynitride thin film layer in the energized state. Under the action of an electric field, the bionic device undergoes a transition from a high-resistance state to a low-resistance state, and transitions from an insulating state to a conductive state. It is equivalent to the "1" state and "0" state in the computer, just as the computer uses "0" and "1" to form codes to store information and realize the storage function. This process is very similar to the behavior of neurotransmitters in synapses, so the synaptic bionic device can simulate the short-term plasticity of neurons.

The neurosynaptic bionic device based on the memristor of this embodiment has the following advantages:

Silicon nitride oxide film is often used as a storage medium. It has the excellent characteristics of silicon nitride and silicon dioxide, and has the potential to replace silicon dioxide film materials in microelectronics and optics. In this embodiment, the copper nanoparticle-doped silicon oxynitride thin film layer is used as the resistive switching functional layer. Under the action of current, it can imitate the characteristics of biological synapses, and its high and low resistance states change slowly and the range is stable; multiple stable resistance states appear. And it has good retention characteristics. When the electrical pulse stimulation is repeatedly applied, the resistance can repeat the high-low resistance transition well, and the synapse bionic device is a step closer to the artificial nerve; the human body's response to the outside world depends on the nervous system in the body. In the transmission of electronic signals, the damage of the nervous system is equivalent to an incomplete circuit, and there is no way to power on. The neurosynaptic bionic device is expected to act as a wire, which is of great significance in the field of biomedicine; it can effectively promote scientists to build efficient and delicate brain bionics The computer improves the efficiency of computer simulation of the human brain; the device has a simple manufacturing process and stable performance, and has broad application prospects.

The preparation method of the above memristor-based synapse bionic device includes:

1) On the upper surface of the first flexible substrate, the silver nanowire ink is sprayed by electrostatic spraying method, and the droplets randomly occupy positions and stack each other to form a silver nanowire wet film, and the surface is attached to the first flexible substrate of the silver nanowire wet film Constant heat treatment in a sealed container to obtain a flexible lower electrode layer; during constant heat treatment, the temperature is controlled at 120-220° C., and the duration is controlled at 30-120 minutes.

2) With the flexible lower electrode layer as the substrate, the temperature of the flexible lower electrode layer is controlled between 25 and 280°C, and the high-purity copper sheet is added to the high-purity nitrogen by radio frequency response magnetron co-sputtering method. On the silicon nitride target, the doping amount of copper is changed by changing the area ratio of the copper sheet on the silicon nitride target to the area ratio of the silicon nitride target, and the area ratio is controlled at 1% to 10%. The distance between the silicon nitride target and the flexible lower electrode layer is 30-70 mm, and after adjusting the vacuum degree to 2×10 ^-4 to 2.5×10 ^-4 Pa, high-purity argon gas is charged to the silicon nitride target Sputter for 8 to 12 minutes to clean the surface of the silicon nitride target, then feed high-purity oxygen so that the oxygen-argon ratio is 10:10sccm, and the radio frequency power is 100W, and continue to sputter the silicon nitride target for 30 to 30 minutes. 60min to form a copper nanoparticle-doped silicon oxynitride thin film layer.

3) moving and rotating the substrate to a suitable position, depositing the copper nanoparticle-doped silicon oxynitride film layer on the flexible lower electrode layer substrate, and performing annealing treatment; the annealing temperature is 300-350°C.

4) On the upper surface of the second flexible substrate, the silver nanowire ink is sprayed by electrostatic spraying method, and the droplets randomly occupy and stack each other to form a silver nanowire wet film, and the surface is attached to the second flexible substrate of the silver nanowire wet film Constant heat treatment in a sealed container to obtain a flexible upper electrode layer. During constant heat treatment, the temperature is controlled at 120-220° C., and the duration is controlled at 30-120 minutes.

5) The flexible upper electrode layer is vertically flipped and then stacked on the copper nanoparticle-doped silicon oxynitride thin film layer.

Both the thickness of the flexible lower electrode layer and the flexible upper electrode layer are 50-350 nm. The thickness of the copper nanoparticle-doped silicon oxynitride film layer is 20-200 nm.

A specific implementation of the preparation method of the memristor-based neurosynaptic bionic device is given below:

(1) Preparation of flexible lower electrode layer: Spray silver nanowire ink on the upper surface of the PI film by electrostatic spraying method, the droplets randomly occupy space and stack each other to form a silver nanowire wet film, and then attach the silver nanowire wet film to the surface The PI thin film was subjected to constant heat treatment in a sealed container, the temperature of constant heat treatment was 200°C, and the treatment time was 100min.

(2) Preparation of flexible upper electrode layer: spray silver nanowire ink on the upper surface of the PI film by electrostatic spraying method, the droplets randomly occupy space and stack each other to form a silver nanowire wet film, and then attach the silver nanowire wet film to the surface The PI thin film was subjected to constant heat treatment in a sealed container, the temperature of constant heat treatment was 200°C, and the treatment time was 100min.

(3) Preparation of copper nanoparticle-doped silicon oxynitride thin film layer: the flexible lower electrode layer is used as the substrate, the substrate temperature is controlled at 260°C, and high-purity Si ₃ N ₄ is used as the target material, and radio frequency reactive magnetron co-sputtering is used Sputtering method, add high-purity metal copper sheet on high-purity Si ₃ N ₄ target, and change the copper doping amount by changing the area ratio of the copper sheet on the sputtering target to the Si ₃ N ₄ target area. The distance between the target and the flexible lower electrode layer is 50 mm. When the vacuum degree of the vacuum chamber reaches 2.2×10 ^-4 Pa, fill the high-purity argon gas with pre-sputtering for 10 minutes to clean the target surface, and then inject high-purity oxygen. The oxygen-argon ratio is 10:10sccm, the radio frequency power is 100W, and the sputtering time is 55min. After the pre-sputtering is stable, the substrate is rotated to a suitable position, and a copper nanoparticle-doped silicon oxynitride film layer is deposited on the substrate.

In the above step (3), the area ratio of the copper sheet to the high-purity Si ₃ N ₄ target is 5%, the annealing temperature is 300° C., and the annealing time is 10 min.

In the above step (1), the thickness of the flexible upper electrode layer and the flexible lower electrode layer is 200 nm; the thickness of the copper nanoparticle-doped silicon oxynitride film layer is 100 nm.

In this paper, specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; meanwhile, for those of ordinary skill in the art, according to the present invention Thoughts, there will be changes in specific implementation methods and application ranges. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims (8)

1. A memristor-based neural synapse-like device, comprising: the flexible electrode comprises a flexible lower electrode layer, a copper nanoparticle doped silicon oxynitride film layer deposited on the flexible lower electrode layer and a flexible upper electrode layer positioned above the copper nanoparticle doped silicon oxynitride film layer;

the flexible lower electrode layer comprises a first flexible substrate and a first silver nanowire transparent electrode positioned above the first flexible substrate; the flexible upper electrode layer comprises a second flexible substrate and a second silver nanowire transparent electrode positioned below the second flexible substrate; the flexible substrate is a PI film;

the lower electrode layer and the upper electrode layer are both prepared by spraying silver nanowire ink on a flexible substrate by adopting an electrostatic spraying method to form a silver nanowire wet film and performing constant heat treatment in a sealed container;

vertically turning over the flexible upper electrode layer and then stacking the flexible upper electrode layer on the copper nanoparticle doped silicon oxynitride film layer;

the copper nanoparticle doped silicon oxynitride film layer is prepared by adding a copper sheet on a silicon nitride target material by adopting a radio frequency reaction magnetron co-sputtering method and introducing oxygen;

the doping amount of copper in the copper nano particle doped silicon oxynitride film layer is 5-23%, and the doping amount of copper is changed by changing the area ratio of the copper sheet on the silicon nitride target material to the area ratio of the silicon nitride target material, so that the area ratio is controlled to be 1-10%;

after the copper nano-particle doped silicon oxynitride film layer is electrified, under the action of an electric field, the copper nano-particle positions which are orderly arranged on the copper nano-particle doped silicon oxynitride film layer start to be scattered, gradually diffuse and penetrate through the film to form a cluster of conductive filaments, and can transfer current from the flexible lower electrode layer to the flexible upper electrode layer; after the power is turned off, the temperature is reduced, and the copper nano particles are rearranged neatly, so that the change of the resistance of the device under the action of an electric field is reflected.

2. The memristor-based neurosynaptic device of claim 1, wherein the thickness of the flexible lower electrode layer and the flexible upper electrode layer are each 50-350 nm.

3. The memristor-based neurite bionic device of claim 1, wherein the thickness of the copper nanoparticle doped silicon oxynitride thin film layer is 20-200 nm.

4. The preparation method of the memristor-based nerve synapse bionic device is characterized by comprising the following steps of:

spraying silver nanowire ink on the upper surface of a first flexible substrate by adopting an electrostatic spraying method to form a silver nanowire wet film, and performing constant heat treatment on the first flexible substrate with the silver nanowire wet film attached to the surface in a sealed container to obtain a flexible lower electrode layer;

the flexible lower electrode layer is taken as a substrate, a radio frequency reaction magnetron co-sputtering method is adopted to add a copper sheet on a silicon nitride target material, the distance between the silicon nitride target material and the flexible lower electrode layer is controlled to be 30-70 mm, and the vacuum degree is adjusted to be 2 multiplied by 10 ^-4 ～2.5×10 ^-4 After Pa, argon is filled into the silicon nitride target material to sputter for 8-12 min, then oxygen is filled into the silicon nitride target material to enable the ratio of oxygen to argon to be 10:10sccm, and the silicon nitride target material is continuously sputtered for 30-60 min to form a copper nanoparticle doped silicon oxynitride film layer;

depositing the copper nanoparticle doped silicon oxynitride film layer on the flexible lower electrode layer substrate, and performing annealing treatment;

spraying silver nanowire ink on the upper surface of a second flexible substrate by adopting an electrostatic spraying method to form a silver nanowire wet film, and performing constant heat treatment on the second flexible substrate with the silver nanowire wet film attached to the surface in a sealed container to obtain a flexible upper electrode layer; the flexible substrate is a PI film;

vertically turning over the flexible upper electrode layer and then stacking the flexible upper electrode layer on the copper nanoparticle doped silicon oxynitride film layer;

the doping amount of copper in the copper nano particle doped silicon oxynitride film layer is 5-23%, and the doping amount of copper is changed by changing the area ratio of the copper sheet on the silicon nitride target material to the area ratio of the silicon nitride target material, so that the area ratio is controlled to be 1-10%;

after the copper nano-particle doped silicon oxynitride film layer is electrified, under the action of an electric field, the copper nano-particle positions which are orderly arranged on the copper nano-particle doped silicon oxynitride film layer start to be scattered, gradually diffuse and penetrate through the film to form a cluster of conductive filaments, and can transfer current from the flexible lower electrode layer to the flexible upper electrode layer; after the power is turned off, the temperature is reduced, and the copper nano particles are rearranged neatly, so that the change of the resistance of the device under the action of an electric field is reflected.

5. The method for preparing the memristor-based nerve synapse bionic device according to claim 4, wherein the constant heat treatment is performed at 120-220 ℃ for 30-120 min.

6. The method for manufacturing a memristor-based neurite bionic device according to claim 4, wherein the temperature of the flexible lower electrode layer in the radio frequency reaction magnetron co-sputtering method is controlled between 25 ℃ and 280 ℃.

7. The method for manufacturing a memristor-based neural synapse-like device as claimed in claim 4, wherein the radio frequency power is controlled to be 100W after oxygen is introduced.

8. The method for preparing the memristor-based nerve synapse bionic device according to claim 4, wherein the area ratio of the copper sheet to the gallium nitride target is 1% -10%, and the annealing temperature is 300-350 ℃.

Images