Hafnium oxide-based ferroelectric ftj memristor and preparation method and chip thereof

Abstract

The application provides a hafnium oxide-based ferroelectric FTJ memristor, which is applied to the technical field of semiconductors and comprises, in sequence, a substrate, a bottom electrode, a ferroelectric layer, an oxide insertion layer and a top electrode, wherein the material of the ferroelectric layer is a ferroelectric material with a ferroelectric polarization effect, and the polarization reversal characteristic is regulated by an external electric field. The application further provides a preparation method of the hafnium oxide-based ferroelectric FTJ memristor and a chip, and can reduce the scale and power consumption of the FTJ memristor.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a hafnium oxide-based ferroelectric FTJ memristor, its fabrication method, and a chip thereof. Background Technology

[0002] Neuromorphic computing simulates the working mechanism of the human brain, possessing advantages such as self-awareness, low power consumption, and self-learning. In the human brain, neurons achieve functions such as learning and memory by altering the synaptic weights between neural synapses. In recent years, artificial biological synaptic electronic devices have been constructed at the device level, simulating the synaptic weights of preceding and following neurons by adjusting the conductance of the electronic devices. These novel artificial synaptic devices may not only become part of highly simulated human brain computers, used in emerging fields such as intelligent robots, medical diagnosis of intractable diseases, and securities trading analysis, but also have broad application prospects in computers that operate by collecting visual, auditory, olfactory, and tactile signals, such as self-driving cars, voice-controlled interfaces, odor recognition, and artificial skin sensing. However, existing FTJ memristors are large in scale and have high power consumption. Summary of the Invention

[0003] The main objective of this invention is to provide a hafnium oxide-based ferroelectric FTJ memristor, its fabrication method, and chip, aiming to solve the technical problems of large device size and high power consumption of existing FTJ memristors.

[0004] To achieve the above objectives, a first aspect of the present invention provides a hafnium oxide-based ferroelectric FTJ memristor, comprising: a substrate, a bottom electrode, a ferroelectric layer, an oxide insertion layer, and a top electrode disposed sequentially.

[0005] The ferroelectric layer is made of a ferroelectric material with ferroelectric polarization effect, and its polarization reversal characteristics are modulated by an applied electric field.

[0006] Optionally, the substrate is made of a highly doped conductive material or an insulating material.

[0007] Optionally, the bottom electrode is made of a conductive thin film material, which can achieve ferroelectric thin film polarization characteristics under the electrode clamping action.

[0008] Optionally, the bottom electrode and the top electrode are made of the same type of electrode material to form a symmetrical barrier height, or the bottom electrode and the top electrode are made of different types of electrode materials to form an asymmetrical barrier height.

[0009] Optionally, the hafnium oxide-based ferroelectric FTJ memristor is used to fabricate crossbar structure devices.

[0010] A second aspect of this invention provides a method for preparing a hafnium oxide-based ferroelectric FTJ memristor, comprising:

[0011] Substrate preparation;

[0012] A bottom electrode is fabricated on the substrate;

[0013] A ferroelectric layer is deposited on the bottom electrode;

[0014] An oxide insertion layer is deposited on the ferroelectric layer;

[0015] A primary top electrode made of the same material as the bottom electrode is deposited on the oxide insertion layer to obtain a composite structure;

[0016] Annealing is performed on the composite structure to activate the ferroelectricity of the ferroelectric layer;

[0017] Etch or corrode the bottom electrode and the original top electrode;

[0018] A new top electrode is prepared to replace the original top electrode.

[0019] Optionally, the substrate is a highly silicon-doped substrate, and the fabrication of the bottom electrode on the substrate includes:

[0020] The global bottom electrode is grown directly on the substrate;

[0021] The substrate is an insulating substrate, and the fabrication of the bottom electrode on the substrate includes:

[0022] Localized bottom electrodes are grown on the substrate, and patterning is achieved by introducing pads through photolithography.

[0023] Optionally, annealing the composite structure row includes:

[0024] The composite structure is subjected to post-metal annealing.

[0025] Optionally, the original top electrode and the bottom electrode are made of the same type of electrode material;

[0026] The new top electrode and the bottom electrode may be made of the same type of electrode material or different types of electrode material.

[0027] A third aspect of the present invention provides a neuromorphic visual sensing chip, including the hafnium oxide-based ferroelectric FTJ memristor described in the first aspect.

[0028] The present invention has the following beneficial effects:

[0029] 1. Advances in microelectronics technology, exemplified by integrated circuits, have led to increasingly significant demands for miniaturization, high density, and low power consumption of basic components. Especially as device feature sizes continue to shrink, and process nodes have reached below 0.1µm, the thickness of the SiO2 dielectric is gradually approaching its physical limit. Hafnium oxide (HfO2) possesses suitable high dielectric constant, high potential barrier, lattice matching with silicon, and good thermal and chemical stability. Hafnium oxide films doped with zirconium (Zr), silicon (Si), or certain rare earth elements exhibit significant ferroelectric properties. Taking zirconium-doped hafnium oxide ferroelectric (HZO) as an example, HZO offers advantages such as compatibility with silicon integrated circuit processes and small size. The electrical properties of HZO can be precisely controlled by simply changing the ALD cycle ratio. Its film thickness reaches the nanometer scale, which is beneficial for device miniaturization, high speed, and low power consumption.

[0030] 2. This invention is based on a hafnium oxide ferroelectric (HZO) FTJ memristor. The unique ferroelectric polarization and non-volatility of ferroelectric materials provide multi-level conductance control capabilities to obtain larger remanent polarization and coercive electric field, thereby optimizing the device structure and fabrication process. The device has advantages such as non-destructive information reading, non-volatility, large doping window, and high remanent polarization, and has broad application prospects in novel information storage and neuromorphic computing chips.

[0031] 3. The present invention employs a top electrode replacement process, which improves the potential barrier at the ferroelectric / metal interface on the one hand, and enhances the flexibility of the device structure on the other. Therefore, the present invention provides an optimized device and process technology solution for improving the performance of hafnium-based FTJ memristor devices in terms of both device structure and process completeness. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the structure of a hafnium oxide-based ferroelectric FTJ memristor provided in an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the PE curve of a hafnium oxide-based ferroelectric FTJ memristor provided in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the hysteresis curve of a hafnium oxide-based ferroelectric FTJ memristor provided in an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of the on / off ratio curve of a hafnium oxide-based ferroelectric FTJ memristor provided in an embodiment of the present invention;

[0037] Figure 5 This is a schematic flowchart of a method for preparing a hafnium oxide-based ferroelectric FTJ memristor according to an embodiment of the present invention;

[0038] Figure 6 This is a schematic diagram of the top electrode replacement of a hafnium oxide-based ferroelectric FTJ memristor provided in an embodiment of the present invention. Detailed Implementation

[0039] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] Please see Figure 1 , Figure 1 This is a schematic diagram of a hafnium oxide-based ferroelectric FTJ memristor provided in an embodiment of the present invention. The hafnium oxide-based ferroelectric FTJ memristor includes a substrate 100, a bottom electrode 200, a ferroelectric layer 300, an oxide insertion layer 400, and a top electrode 500 arranged sequentially. The ferroelectric layer 300 is made of a ferroelectric material with ferroelectric polarization effect, and its polarization reversal characteristics are controlled by an applied electric field.

[0041] In one embodiment of the present invention, the substrate 100 is made of a highly doped conductive material or an insulating material, including but not limited to highly doped silicon / silicon dioxide, sapphire, low-resistivity silicon, silicon carbide, germanium, diamond, or flexible materials.

[0042] In one embodiment of the present invention, the bottom electrode 200 is made of a conductive thin film material, which can achieve ferroelectric thin film polarization characteristics under electrode clamping. Specifically, the bottom electrode 200 is either directly grown on the substrate 100 or patterned on the substrate 100. The electrode material is a conductive thin film material with good conductivity, such as tungsten metal, titanium nitride, indium tin oxide (ITO), tantalum nitride, gold, platinum, and other metal materials.

[0043] Furthermore, global bottom electrodes 200 can be fabricated or local bottom electrode patterns can be fabricated by photolithography as needed, but this needs to be compatible with the substrate material 100 used. For example, when using a highly silicon-doped conductive substrate 100, global bottom electrodes 200 are selected to achieve bottom-level power application. If an insulating substrate 100 such as a Si / SiO2 composite substrate 100 is used, local bottom electrodes 200 are used, and patterning is achieved by introducing pads through photolithography.

[0044] In one embodiment of the present invention, the material of the ferroelectric layer 300 includes, but is not limited to, ferroelectric functional materials such as hafnium oxide doped with silicon / zirconium / yttrium / aluminum. The material is required to have ferroelectric polarization characteristics and good non-volatility, and can be prepared by atomic layer deposition or chemical vapor deposition.

[0045] In one embodiment of the present invention, the material of the oxide insertion layer 400 includes, but is not limited to, oxide materials such as aluminum oxide and silicon oxide, and has a small dielectric constant and good compactness.

[0046] In one embodiment of the present invention, the top electrode 500 is a new top electrode after replacement. Both the bottom electrode 200 and the top electrode 500 are made of metallic materials, including but not limited to, for example, tungsten, titanium nitride, tantalum nitride, titanium / gold, platinum / gold, ITO transparent electrodes, chromium / gold electrodes, or composite electrodes. The bottom electrode 200 and the top electrode 500 can be made of the same electrode material to form a symmetrical barrier height, or they can be made of different types of electrode materials to form an asymmetrical barrier height. Furthermore, the metallic electrodes can also be interdigitated metal electrodes, forming a crossbar structure, which is beneficial for large-scale device integration or application in neuromorphic visual sensing chips.

[0047] In one embodiment of the present invention, the hafnium oxide-based ferroelectric FTJ memristor is used to fabricate a crossbar structure device.

[0048] Figure 2 This is a schematic diagram of the PE curve of a hafnium oxide-based ferroelectric FTJ memristor provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the hysteresis curve of a hafnium oxide-based ferroelectric FTJ memristor provided in an embodiment of the present invention. Figure 4 This is a schematic diagram of the on / off ratio curve of a hafnium oxide-based ferroelectric FTJ memristor provided in an embodiment of the present invention.

[0049] Figure 2The figure presents curves of ferroelectric polarization intensity (vertical axis P) versus applied electric field intensity (horizontal axis E) of the ferroelectric medium under different scanning voltages. When the scanning voltage range is small, the device window is small, and the corresponding residual polarization charge density is small. As the scanning voltage range increases, the device window increases accordingly. Different voltage ranges represent different ferroelectric film states. The PE curves show that the device of this invention, with a radius of 100 μm, has a residual polarization intensity as high as 20 μC / cm² under a 1 kHz scan. 2 ,Depend on Figure 3 and Figure 4 The results of the DC characteristics of the device show that the device has obvious high and low resistance states, indicating that the device achieves effective modulation of conductance under the action of external voltage.

[0050] Please see Figure 5 , Figure 5 Provided for an embodiment of the present invention Figure 1 The diagram shows a flow chart of the fabrication method for a hafnium oxide-based ferroelectric FTJ memristor. Figure 6 This is a schematic diagram of the top electrode replacement of a hafnium oxide-based ferroelectric FTJ memristor according to an embodiment of the present invention. The method mainly includes the following steps:

[0051] S1. Prepare substrate 100.

[0052] S2. Prepare a bottom electrode 200 on the substrate.

[0053] Specifically, the bottom electrode 200 can be fabricated on the substrate 100 by electron beam evaporation or magnetron sputtering. The bottom electrode 200 is, for example, tungsten metal, and the thickness of the tungsten metal is, for example, 10-30 nm.

[0054] In one embodiment of the present invention, the substrate 100 is a highly silicon-doped substrate, and the fabrication of the bottom electrode 200 on the substrate 100 includes: directly growing a global bottom electrode on the substrate 100. Alternatively, if the substrate 100 is an insulating substrate, the fabrication of the bottom electrode 200 on the substrate 100 includes: growing a local bottom electrode 200 on the substrate 100, and patterning it by introducing a pad using photolithography. Depending on the substrate material, either a global bottom electrode 200 or a local bottom electrode 200 can be selected. A global bottom electrode 200, compared to a local bottom electrode 200, can reduce the on / off ratio of the leakage current boosting device.

[0055] S3. A ferroelectric layer 300 is deposited on the bottom electrode 200.

[0056] Specifically, a ferroelectric layer 300 is prepared on the bottom electrode 200 by atomic layer deposition or vapor deposition, wherein the zirconium-doped hafnium oxide needs to be activated for ferroelectricity through annealing. The thickness of the ferroelectric layer 300 is, for example, 6-10 nm.

[0057] S4. Deposit an oxide insertion layer 400 on the ferroelectric layer 300.

[0058] Specifically, an oxide insertion layer 400 is fabricated on top of the ferroelectric layer 300 using methods such as atomic layer deposition or vapor phase deposition. The oxide insertion layer 400 uses a material with a low dielectric constant, which results in lower dielectric loss to further reduce device leakage current and improve its on / off ratio characteristics. The thickness of the oxide insertion layer 400 is, for example, 2-3 nm.

[0059] S5. A primary top electrode 600 of the same material as the bottom electrode is deposited on the oxide insertion layer 400 to obtain a composite structure.

[0060] Specifically, the top electrode is grown by electron beam evaporation or sputtering, and it has the same material as the bottom electrode 200 to achieve the clamping effect of the ferroelectric layer and oxide insertion layer between the bottom electrode 200 and the original top electrode 600. The thickness of the original top electrode 600 is, for example, 30-60 nm.

[0061] S6. Anneal the composite structure to activate the ferroelectricity of the ferroelectric layer 300.

[0062] In one embodiment of the present invention, annealing the composite structure row includes: performing post-metallization (PMA) annealing on the composite structure row to activate the ferroelectricity of the ferroelectric layer 300, wherein the annealing temperature is, for example, 500°C, the time is, for example, 30 seconds, and the process is carried out in a nitrogen atmosphere. Compared to dielectric post-annealing (PDA), this process is advantageous in achieving a higher remanent polarization intensity of the ferroelectric layer, thereby improving the retention characteristics of the device.

[0063] S7. Etch or corrode the bottom electrode 200 and the original top electrode 600.

[0064] S8. Prepare a new top electrode 500 to replace the original top electrode 600.

[0065] Specifically, the top electrode is removed by etching, and a new top electrode is fabricated by combining photolithography-electron beam evaporation or sputtering. The fabrication methods include, but are not limited to, optical lithography and electron beam lithography to pattern the new top electrode.

[0066] In one embodiment of the present invention, the top electrode 600 and the bottom electrode 200 are made of the same type of electrode material, and the new top electrode 500 and the bottom electrode 200 are made of the same type of electrode material or different types of electrode material.

[0067] Hafnium oxide-based ferroelectric FTJ memristors are fabricated through top electrode replacement. Firstly, the original top electrode 600 and bottom electrode 200, made of the same material, facilitate the formation of the ferroelectric phase and enhance remanent polarization. Secondly, the material of the new top electrode 500 after replacement can be selected according to different device applications, increasing the flexibility of the device structure.

[0068] The present invention also provides a neuromorphic visual sensing chip, comprising: Figure 1 The hafnium oxide-based ferroelectric FTJ memristor is shown.

[0069] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0070] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0071] The above is a description of a hafnium oxide-based ferroelectric FTJ memristor, its preparation method, and the chip provided by the present invention. For those skilled in the art, based on the ideas of the embodiments of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A hafnium oxide-based ferroelectric FTJ memristor, characterized in that, include: The substrate, bottom electrode, ferroelectric layer, oxide insertion layer, and replaced top electrode are sequentially arranged. The ferroelectric layer is made of a ferroelectric material with ferroelectric polarization effect, and its polarization reversal characteristics are modulated by an applied electric field. The ferroelectric material is zirconium-doped hafnium oxide with a thickness of 6 nm to 10 nm. The hafnium oxide-based ferroelectric FTJ memristor exhibits a strength greater than or equal to 20 μC / cm² at a 1 kHz scan frequency. 2 The residual polarization intensity; The replacement process of the top electrode is obtained through the following method: A tungsten metal material layer is deposited on the oxide insertion layer to obtain a composite structure consisting of the substrate, the bottom electrode, the ferroelectric layer, the oxide insertion layer, and the tungsten metal material layer; In the presence of the tungsten metal material layer, the composite structure is subjected to post-metal annealing to activate the ferroelectricity of the ferroelectric layer; After annealing, the tungsten metal material layer is removed by etching; A top electrode is fabricated on the oxide insertion layer using photolithography to replace the tungsten metal material layer.

2. The hafnium oxide-based ferroelectric FTJ memristor according to claim 1, characterized in that, The substrate is made of a highly doped conductive material or an insulating material.

3. The hafnium oxide-based ferroelectric FTJ memristor according to claim 1, characterized in that, The bottom electrode is made of a conductive thin film material, which can achieve ferroelectric thin film polarization characteristics under the action of electrode clamping.

4. The hafnium oxide-based ferroelectric FTJ memristor according to claim 1, characterized in that, The bottom electrode and the top electrode are made of the same type of electrode material to form a symmetrical barrier height, or the bottom electrode and the top electrode are made of different types of electrode materials to form an asymmetrical barrier height.

5. The hafnium oxide-based ferroelectric FTJ memristor according to claim 1, characterized in that, The hafnium oxide-based ferroelectric FTJ memristor is used to fabricate crossbar structure devices.

6. A method for preparing a hafnium oxide-based ferroelectric FTJ memristor, characterized in that, include: Substrate preparation; A bottom electrode is fabricated on the substrate; A ferroelectric layer is deposited on the bottom electrode, the thickness of the ferroelectric layer being 6 nm to 10 nm; An oxide insertion layer is deposited on the ferroelectric layer; A tungsten metal material layer is deposited on the oxide insertion layer to obtain a composite structure consisting of the substrate, the bottom electrode, the ferroelectric layer, the oxide insertion layer, and the tungsten metal material layer, wherein the bottom electrode material is tungsten; In the presence of the tungsten metal material layer, the composite structure is subjected to post-metal annealing to activate the ferroelectricity of the ferroelectric layer; After annealing, the tungsten metal material layer is removed by etching; A top electrode is fabricated on the oxide insertion layer using photolithography to replace the tungsten metal material layer.

7. The method for preparing a hafnium oxide-based ferroelectric FTJ memristor according to claim 6, characterized in that, The substrate is a highly silicon-doped substrate, and the fabrication of the bottom electrode on the substrate includes: The global bottom electrode is grown directly on the substrate; The substrate is an insulating substrate, and the fabrication of the bottom electrode on the substrate includes: Localized bottom electrodes are grown on the substrate, and patterning is achieved by introducing pads through photolithography.

8. The method for preparing a hafnium oxide-based ferroelectric FTJ memristor according to claim 6, characterized in that, The top electrode and the bottom electrode obtained by replacement can be made of the same type of electrode material or different types of electrode material.

9. A neuromorphic visual sensing chip, characterized in that, Includes the hafnium oxide-based ferroelectric FTJ memristor as described in any one of claims 1 to 5.

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