阅读说明：本技术 畴壁存储器的制备方法以及畴壁存储器 (Method for producing domain wall memory and domain wall memory ) 是由 胡来归 蔡依辰 詹义强 秦亚杰 于 2021-07-27 设计创作，主要内容包括：本发明提供了一种有机铁电畴壁存储器的制备方法,包括如下步骤：提供一衬底；在所述衬底上制作对置的金属梳状电极；对所述衬底表面进行亲疏水性处理；在所述衬底表面采用选区生长法形成分子铁电功能层；退火后获得畴壁存储器。上述技术方案实现了基于梳状对电极的多级长度沟道以及有机铁电层部分极化形成畴壁导电通道。利用低张力滴涂选区法,降低成本与复杂度的同时引导极化轴可控生长。与传统利用极化翻转与位移电流写入与读取的铁电存储器相比,具有非破坏性读取、电流信号大、寿命长等优势。本发明可用于新型存储阵列、柔性集成铁电芯片等领域。(The invention provides a preparation method of an organic ferroelectrics domain wall memory, which comprises the following steps: providing a substrate; manufacturing opposite metal comb electrodes on the substrate; carrying out hydrophilic and hydrophobic treatment on the surface of the substrate; forming a molecular ferroelectric functional layer on the surface of the substrate by adopting a selective area growth method; after annealing, a domain wall memory is obtained. According to the technical scheme, the multi-stage length channel based on the comb-shaped counter electrode and the domain wall conductive channel formed by partial polarization of the organic ferroelectric layer are realized. And a low-tension drop coating selection area method is utilized, so that the cost and the complexity are reduced, and the controllable growth of the polarization axis is guided. Compared with the traditional ferroelectric memory which utilizes polarization reversal and displacement current writing and reading, the ferroelectric memory has the advantages of nondestructive reading, large current signal, long service life and the like. The invention can be used in the fields of novel memory arrays, flexible integrated ferroelectric chips and the like.)

1. A preparation method of an organic ferroelectric domain wall memory is characterized by comprising the following steps:

providing a substrate;

manufacturing opposite metal comb electrodes on the substrate;

carrying out hydrophilic and hydrophobic treatment on the surface of the substrate;

forming a molecular ferroelectric functional layer on the surface of the substrate by adopting a selective area growth method;

after annealing, a domain wall memory is obtained.

2. The method according to claim 1, characterized in that the material of the molecular ferroelectric functional layer is diisopropylamine bromide salt crystals.

3. The method of claim 1, wherein the substrate is selected from the group consisting of silicon, silicon oxide, glass, PI, PET, and PDMS.

4. The method of claim 1, wherein the comb electrodes have a first pitch and a second pitch.

5. The method of claim 4, wherein the comb-shaped electrode is a square sawtooth comb-shaped counter electrode, and comb-shaped teeth of the two electrodes are arranged in a manner of being opposite in front to form a characteristic functional channel pattern with periodic width variation; the patterning method is selected from one of photolithography, laser direct writing, imprinting, and electron beam exposure.

6. The method of claim 1, wherein the comb electrode fabrication process is one of vacuum resistive thermal evaporation deposition, electron beam deposition, and magnetron sputtering.

7. The method of claim 1, wherein the comb electrode is 50nm thick

150nm, the electrode spacing is 1-30 μm, the period of the rectangular saw teeth is 5-50 μm, and the side length of each saw tooth is 2-30 μm.

8. The method according to claim 1, wherein in the step of performing hydrophilic and hydrophobic treatment on the surface of the substrate, the channel region where the material is required to grow is subjected to hydrophilic treatment, and oxygen plasma is selected for cleaning. And (3) carrying out hydrophobic treatment on the surface of the electrode without material growth, and selecting one of mercaptan treatment and octadecyl trichlorosilane treatment.

9. The method of claim 1, wherein the molecular ferroelectric functional layer is prepared by selective inter-electrode solution method growth induced by surface tension.

10. An organic ferroelectric domain wall memory, comprising: a substrate; opposed comb electrodes on the surface of the substrate; and a molecular ferroelectric functional layer between the opposing comb electrodes.

Technical Field

The invention relates to the field of semiconductor devices, in particular to a preparation method of an organic ferroelectric domain wall memory and a domain wall memory.

Background

With the rapid development of information technology, storeMemory is under increasing pressure as a memory device for computer systems. Non-volatile memories, represented by floating gate transistors, are the basis for future high performance low power consumption calculations, however the injection and extraction of charge makes switching slow and operating voltages high. The non-volatile memory based on the inorganic ferroelectric material has the advantages of high switching speed, small operating voltage and long service life, but contains more toxic elements, and has complex preparation process and low compatibility. Ferroelectric polymers represented by PVDF and copolymers thereof are gaining wide attention in the wearable field due to the characteristics of flexibility and flexible preparation. However, the coercive field E of the ferroelectric polymer_cToo large and small spontaneous polarization restrict practical application. In recent years, the molecular ferroelectric material has made breakthrough progress, and the spontaneous polarization of diisopropylamine bromide (DIPAB) crystal reaches 23 mu C/cm²Of which E_cOnly 5 kV/cm. The excellent performance of the compound is close to that of inorganic ferroelectrics, and the flexible preparation process provides new possibility for novel molecular ferroelectric devices. In addition, the writing and reading of the conventional ferroelectric nonvolatile memory are accompanied by polarization reversal, which affects the performance and the service life of the device. Meanwhile, the phenomenon of enhancing the interface conductivity of the ferroelectric material is taken as a special controllable conductivity modulation principle, and the ferroelectric material has great application potential. The two-terminal memory inorganic device based on ferroelectric domain wall conduction is used as a nonvolatile non-destructive current mode memory device, and brings new opportunity for the application of ferroelectric materials in novel memories.

Disclosure of Invention

The invention aims to solve the technical problem of providing a preparation method of an organic ferroelectric domain wall memory which is nondestructively read, nonvolatile, simple and controllable to prepare and a domain wall memory.

In order to solve the above problems, the present invention provides a method for preparing an organic ferroelectric domain wall memory, comprising the steps of: providing a substrate; manufacturing opposite metal comb electrodes on the substrate; carrying out hydrophilic and hydrophobic treatment on the surface of the substrate; forming a molecular ferroelectric functional layer on the surface of the substrate by adopting a selective area growth method; after annealing, a domain wall memory is obtained.

Optionally, the material of the molecular ferroelectric functional layer is diisopropylamine bromide salt crystals.

Optionally, the substrate is selected from one of silicon, silicon oxide, glass, PI, PET, or PDMS.

Optionally, the comb electrodes have a first pitch and a second pitch.

Optionally, the comb-shaped electrode is a square sawtooth comb-shaped counter electrode, and the front faces of the comb-shaped teeth of the two electrodes are arranged oppositely to form a characteristic functional channel pattern with periodic width variation; the patterning method is selected from one of photolithography, laser direct writing, imprinting, and electron beam exposure.

Optionally, the comb-shaped electrode preparation process may be one of vacuum resistance thermal evaporation deposition, electron beam deposition and magnetron sputtering.

Optionally, the thickness of the comb-shaped electrode is 50nm-150nm, the electrode spacing is 1 μm-30 μm, the period of the rectangular saw teeth is 5 μm-50 μm, and the side length of a single saw tooth is 2 μm-30 μm.

Optionally, performing hydrophilic and hydrophobic treatment on the surface of the substrate, performing hydrophilic treatment on a channel region where a material is required to grow, and cleaning by using oxygen plasma. And (3) carrying out hydrophobic treatment on the surface of the electrode without material growth, and selecting one of mercaptan treatment and octadecyl trichlorosilane treatment.

Optionally, the preparation method of the molecular ferroelectric functional layer is selective area growth by an inter-electrode solution method induced by surface tension.

In order to solve the above problems, the present invention provides an organic ferroelectric domain wall memory comprising: a substrate; opposed comb electrodes on the surface of the substrate; and a molecular ferroelectric functional layer between the opposing comb electrodes.

According to the technical scheme, the multi-stage length channel based on the comb-shaped counter electrode and the domain wall conductive channel formed by partial polarization of the organic ferroelectric layer are realized. And a low-tension drop coating selection area method is utilized, so that the cost and the complexity are reduced, and the controllable growth of the polarization axis is guided. Compared with the traditional ferroelectric memory which utilizes polarization reversal and displacement current writing and reading, the ferroelectric memory has the advantages of nondestructive reading, large current signal, long service life and the like. The invention can be used in the fields of novel memory arrays, flexible integrated ferroelectric chips and the like.

Drawings

FIG. 1 is a schematic diagram illustrating the steps of one embodiment of the present invention.

Fig. 2A to 2C show a process flow diagram of an embodiment of the present invention.

FIG. 3 is a photograph showing optical microscopic characterization of a device fabricated in accordance with this embodiment.

Figure 4 is an optical microscopic characterization photograph of the magnified channel region of a device made in accordance with this embodiment.

Detailed Description

The method for manufacturing a domain wall memory and the specific embodiment of the domain wall memory according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram illustrating the steps of the present embodiment, including: step S10, providing a substrate; step S11, forming opposing metal comb electrodes on the substrate; step S12, carrying out hydrophilic and hydrophobic treatment on the surface of the substrate; step S13, forming a molecular ferroelectric functional layer on the surface of the substrate by adopting a selective area growth method; in step S14, a domain wall memory is obtained after annealing.

In this embodiment, an organic molecule ferroelectric material, namely diisopropylamine bromide (represented by DIPAB), is used as a ferroelectric control layer, and the structural formula is as follows:

fig. 2A to 2C are process flow diagrams of the present embodiment.

Referring to step S10, shown in fig. 2A, a substrate 20 is provided. The substrate 20 is selected from one of silicon, silicon oxide, glass, PI, PET or PDMS, and in this embodiment, is a silicon oxide substrate.

Referring to step S11, shown in fig. 2B, opposing metal comb electrodes 21 are fabricated on the substrate 20. The preparation process of the comb-shaped electrode can be one of vacuum resistance thermal evaporation deposition, electron beam deposition and magnetron sputtering. In order to improve the device performance, in the present embodiment, the comb-shaped electrode has a first pitch and a second pitch, the comb-shaped electrode 21 is a square sawtooth comb-shaped counter electrode, and the comb-shaped teeth of the two electrodes are arranged in a front-to-front manner to form a characteristic functional channel pattern with periodic width variation; the patterning method is selected from one of photolithography, laser direct writing, imprinting, and electron beam exposure. Specifically, a comb-shaped counter electrode photoetching mask meeting the function is designed according to the performance requirements of the device, deep ultraviolet photoetching and vacuum thermal evaporation resistance are used for depositing on the surface of clean silicon oxide to prepare an electrode, the thickness of the comb-shaped electrode is 50nm-150nm, the electrode distance is 1 mu m-30 mu m, the period of rectangular saw teeth is 5 mu m-50 mu m, and the side length of each single saw tooth is 2 mu m-30 mu m. And (3) respectively immersing the substrate of the prepared electrode in acetone, isopropanol and deionized water in sequence, carrying out low-frequency ultrasound for 1 minute, blowing residual liquid by using a nitrogen gun, and drying on a hot plate at 100 ℃ for later use.

Step S12, carrying out hydrophilic and hydrophobic treatment on the surface of the substrate. And carrying out hydrophilic treatment, and optionally cleaning with oxygen plasma, on the channel region where the required material grows. The surface of the electrode without material growth is subjected to hydrophobic treatment, and one of mercaptan treatment and octadecyl trichlorosilane treatment can be selected.

Referring to step S13 and step S14, a domain wall memory is obtained by annealing a molecular ferroelectric functional layer 22 formed on the surface of the substrate 20 by a selective area growth method as shown in fig. 2C. In the present embodiment, the material of the molecular ferroelectric functional layer is diisopropylamine bromide (DIPAB) crystal, and the preparation method of the molecular ferroelectric functional layer is selective growth between electrodes by a solution method induced by surface tension. Specifically, a 5mg/ml DIPAB methanol solution was prepared, and DIPAB powder (10 mg) was weighed using an electronic balance, and 2ml of an anhydrous methanol solvent was sucked up using a syringe, placed in a sealed bottle, and sufficiently dissolved by sonication for 5 minutes. Then, the substrate with the gold electrode pattern is preheated for 5 minutes on a hot plate with the temperature of 60 ℃, 20 microliter of solution is quickly dripped on the surface of the substrate by a liquid transfer gun, a selective growth molecular ferroelectric functional layer is prepared by a low-tension dripping method, and after film formation, the substrate is dried and annealed for half an hour at the temperature of 100 ℃.

The domain wall memory obtained after the implementation of the steps comprises the following steps: a substrate 20; an opposed comb electrode 21 on the surface of the substrate 20; and a molecular ferroelectric functional layer 22 between the opposing comb electrodes.

The functional molecular material film of the molecular ferroelectric domain wall memory device prepared by the selective area growth method prepared by the low-tension dripping method only exists in a channel area between electrodes. The device was characterized by optical microscopy, as shown in fig. 3, with no material covering the gold electrode surface and a continuous smooth ferroelectric thin film in the channel region. Enlarged channel region observation shows that the thin film material has better conformality and presents a complex channel shape, the detailed dimension of the channel is shown as the minimum position of the channel is 5 μm in figure 4. The organic molecule ferroelectric material can realize ferroelectric polarization reversal in a plane and has high-performance in-plane ferroelectric property. The domain wall memory processes the narrow channel region material by voltage polarization, and keeps the ferroelectric material which does not affect the wide channel region, so that the domain wall between the narrow/wide regions is generated or disappears, and the nonvolatile memory is realized.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.