Preparation method and application of ferroelectric diode based on scandium-doped aluminum nitride film

Abstract

The invention belongs to the field of microelectronics, and particularly relates to a preparation method and application of a ferroelectric diode based on a scandium-doped aluminum nitride thin film, and the ferroelectric diode is prepared through the following steps: S1, growing an adhesion layer on a substrate through magnetron sputtering; s2, growing a bottom electrode on the adhesion layer through magnetron sputtering; s3, growing a ferroelectric film on the bottom electrode through magnetron co-sputtering at room temperature; s4, coating photoresist on the ferroelectric film, and exposing and developing; s5, growing a top electrode on the exposed and developed ferroelectric film through magnetron sputtering; and S6, stripping to obtain the ferroelectric diode. Compared with the prior art, the method has the advantages that the problems of high preparation temperature of the Al1-xScxN layer and large thickness of the Al1-xScxN layer in the prior art are solved, the ferroelectric diode memory of the scandium-doped aluminum nitride film is prepared at room temperature for the first time, and compatibility with a CMOS (complementary metal oxide semiconductor) process is better realized.

Description

Technical Field

[0001] The present invention belongs to the field of microelectronics, and particularly relates to a preparation method and application of a ferroelectric diode based on a scandium-doped aluminum nitride thin film. Background Art

[0002] With the continuous evolution of science and technology, the amount of data in today's society shows an increasing trend. Traditional memories no longer have the ability to process data quickly. New device application technologies such as Internet of Things (IoT) devices, non-von Neumann computing architectures, and artificial intelligence (AI) computing algorithms all need to operate at high speed and low power consumption. Using non-volatile memories in these technologies is one of the effective methods to improve the operation speed while reducing power consumption. For non-volatile memory applications that require low power consumption, high speed, high write, and high durability, ferroelectric memories (FeRAMs) are rapidly becoming the preferred memories. In these ferroelectric capacitors, a relatively thick ferroelectric thin film is usually sandwiched between two electrodes, and the remaining polarization is switched by applying an electric field between the electrodes. However, the capacitive readout (polarization) of information prevents the scalability of FeRAMs up to gigabit density and requires destructive readout. Ferroelectric tunneling junctions (FTJs) and ferroelectric diodes (FE diodes) have the potential to achieve high-density crossbar arrays and can achieve non-destructive reading.

[0003] FTJs require an additional selector, while ferroelectric diodes have a built-in selector due to the diode rectification effect, making them very advantageous for the unit density of storage device cells. FTJs should have a thin ferroelectric insulating barrier to achieve direct quantum tunneling. Ferroelectric diodes do not rely on direct tunneling but on polarization-dependent defect-assisted tunneling, FN tunneling, or leakage current, and have the potential to obtain inherent nonlinearity and achieve selectorless cross-point integration. The Fe diode concept was first proposed in PZT perovskite thin films and later in bulk BFO single crystals. The low switching ratio and ultra-thick thin films limit their miniaturization. By comparing different ferroelectric materials, it is found that the polarization intensity of the Al 1-x Sc x N material is higher than that of HZO, and the growth temperature is lower than 400 °C without post-annealing, which is suitable for use in FE diodes.

[0004] However, nowadays, using Al 1-x Sc xN material is used in Fe diode, and its preparation conditions are all at 300-400°C. For example, CN116828971A discloses a ferroelectric diode based on doped aluminum nitride film and its preparation method, wherein the ferroelectric layer is grown by atomic layer deposition at a temperature of 250-450°C, which is difficult to be compatible with the existing CMOS process; and its thickness is at least about 45nm. As a result, due to the thicker ferroelectric film, its operating voltage is large, the readout current is low, and the storage density is low, which limits their miniaturization, integration, and cannot be prepared at room temperature to be compatible with CMOS.

[0005] Therefore, it is necessary to propose a method for preparing ferroelectric diodes based on scandium-doped aluminum nitride films at room temperature to be compatible with existing CMOS processes. Summary of the invention

[0006] The purpose of the present invention is to solve at least one of the above problems and to provide a method for preparing a ferroelectric diode based on scandium-doped aluminum nitride film and its application, so as to solve the problem of Al 1-x Sc x The preparation temperature of the N layer is high, and the Al 1-x Sc x The problem of thick N layer was solved by preparing ferroelectric diode memory of scandium-doped aluminum nitride film at room temperature for the first time, which better achieved compatibility with CMOS process.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] The first aspect of the present invention discloses a method for preparing a ferroelectric diode based on a scandium-doped aluminum nitride film, wherein the ferroelectric diode is formed by stacking a substrate, an adhesion layer, a bottom electrode, a ferroelectric film and a top electrode in sequence, wherein the ferroelectric film is Al 1-x Sc x N ferroelectric thin film;

[0009] The ferroelectric diode is prepared by the following steps:

[0010] S1: growing an adhesion layer on the substrate by magnetron sputtering;

[0011] S2: growing the bottom electrode on the adhesion layer by magnetron sputtering;

[0012] S3: growing a ferroelectric thin film on the bottom electrode by magnetron co-sputtering at room temperature;

[0013] S4: coating photoresist on the ferroelectric film and exposing and developing it;

[0014] S5: growing a top electrode on the exposed and developed ferroelectric film by magnetron sputtering;

[0015] S6: Stripping to obtain the ferroelectric diode described above.

[0016] Preferably, the substrate is a silicon-based substrate; the adhesion layer is a metal adhesion layer or an oxide adhesion layer; the bottom electrode is a metal bottom electrode or a nitride bottom electrode; the top electrode is a metal bottom electrode or a nitride bottom electrode.

[0017] Preferably, the adhesion layer is selected from any one of an Au adhesion layer, a Co adhesion layer, an Si adhesion layer, a Ti adhesion layer, a Cr adhesion layer, a Ru adhesion layer, a TiN adhesion layer, and a TiO2 adhesion layer, with a thickness of 0.5 - 20 nm; the bottom electrode is selected from any one of an Au bottom electrode, a W bottom electrode, an Ag bottom electrode, a Ti bottom electrode, an Al bottom electrode, a TiN bottom electrode, a Pt bottom electrode, a GaN bottom electrode, a Mo bottom electrode, and a Ta bottom electrode, with a thickness of 10 - 50 nm; the ferroelectric thin film is an Al 1-x Sc x N ferroelectric thin film, where x = 0.1 - 0.4 and the thickness is 5 - 50 nm; the top electrode is selected from any one of an Au top electrode, a W top electrode, an Ag top electrode, a Ti top electrode, an Al top electrode, a TiN top electrode, a Pt top electrode, a GaN top electrode, a Mo top electrode, a Ta top electrode, and a Pd top electrode, with a thickness of 10 - 50 nm.

[0018] Preferably, in step S1, the adhesion layer is grown on the substrate by DC magnetron sputtering.

[0019] Preferably, in step S2, the bottom electrode is grown on the adhesion layer by DC magnetron sputtering.

[0020] Preferably, in step S3, the co-sputtering by magnetron is as follows: under a nitrogen-argon mixed atmosphere, co-sputtering is performed using an AlSc alloy target and a Sc target. Among them, the AlSc alloy target uses a pulsed DC magnetron sputtering power of 300 W, the pulse frequency is 100 kHz, and the Sc target uses a radio frequency magnetron sputtering power of 50 W; the pressure of the nitrogen-argon mixed atmosphere is 3 mTorr, and the nitrogen partial pressure is 80%.

[0021] Preferably, in step S4, after applying negative photoresist on the surface of the ferroelectric thin film, it is heated at 150 °C for 2 min, exposed at 120 °C for 2 min, soaked in the developer for 45 s for development, then washed with deionized water, and dried with an inert gas.

[0022] Preferably, in step S5, the top electrode is grown on the ferroelectric thin film after exposure and development by DC magnetron sputtering.

[0023] Preferably, in step S6, the stripping includes: soaking successively in acetone and absolute ethanol, then washing with deionized water, and drying with an inert gas.

[0024] The second aspect of the present invention discloses an application of a ferroelectric diode prepared by the method described in any one of the above in a ferroelectric memory.

[0025] The working principle of the present invention is as follows:

[0026] It is difficult to obtain a high-quality insulating film by DC magnetron sputtering. The disadvantages of RF magnetron sputtering are low deposition rate and high RF power cost. The advantage of pulsed DC magnetron sputtering method is high deposition rate, which is suitable for producing high-quality and cost-effective dielectric films. In addition, since the electronegativity of Sc atoms is less than that of Al atoms, the proportion of ionic bonds in the Al 1-x Sc x N thin film increases, so it is beneficial to prepare a thin film with high crystallinity even at room temperature.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The invention discloses a preparation method of a ferroelectric diode based on scandium-doped aluminum nitride thin film. The ferroelectric diode includes a silicon-based substrate, a metal or oxide adhesion layer, a metal or nitride bottom electrode, Al 1-x Sc x N ferroelectric thin film and a metal or nitride top electrode stacked in sequence. For the first time, a ferroelectric diode memory of scandium-doped aluminum nitride thin film is prepared at room temperature, showing high crystallization quality, superior ferroelectric properties, and having advantages such as high switching ratio, superior reliability, low operating voltage, and high readout current.

[0029] The ferroelectric diode of the present invention is better compatible with the CMOS process. It can not only work at a lower operating voltage (±4V), but also has high ferroelectric properties (the remanent polarization value 2Pr is 238 μC / cm 2 ), and excellent ferroelectric diode effect, providing a new thinking direction and research method for realizing emerging application technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic structural diagram of a ferroelectric diode prepared by the method of the present invention;

[0031] Figure 2 is the ferroelectric property diagram of P-E and J-E of the TiN / Al 0.7 Sc 0.3 N / Pt / Ti / SiO2 / Si device prepared in Example 1;

[0032] Figure 3 is the TiN / Al 0.7 Sc 0.3I-V characteristic curve of ferroelectric diode of N / Pt / Ti / SiO2 / Si device;

[0033] Figure 4 For TiN / Al prepared in Example 1 0.7 Sc 0.3 Distribution diagrams of high and low resistance states of N / Pt / Ti / SiO2 / Si device with different number of cycles;

[0034] Figure 5 XRD characterization comparison diagram of Example 1, Comparative Example 1 and Comparative Example 2;

[0035] In the figure: 1 - substrate; 2 - adhesion layer; 3 - bottom electrode; 4 - ferroelectric thin film; 5 - top electrode. Detailed implementation mode

[0036] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] In the following description, if not otherwise specified, the reagents used are conventional commercially available products, and the methods used are well-known means in the art.

[0038] Various structural schematic diagrams according to embodiments of the present disclosure are shown in the accompanying drawings. These figures are not drawn to scale, and for the purpose of clear expression, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are only exemplary. In practice, there may be deviations due to manufacturing tolerances or technical limitations, and those skilled in the art can design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0039] The ferroelectric diodes in the following embodiments all have the following structure:

[0040] Specifically, please refer to Figure 1 , which is a schematic structural diagram of the Al 1-x Sc x N ferroelectric diode of the present invention. The device structure includes a silicon-based substrate 1, a metal or oxide adhesion layer 2, a metal or nitride bottom electrode 3, and Al 1-x Sc xN ferroelectric thin film 4 and a metal or nitride top electrode 5; specifically, the metal or oxide adhesion layer 2 is selected from any one of an Au adhesion layer 2, a Co adhesion layer 2, a Si adhesion layer 2, a Ti adhesion layer 2, a Cr adhesion layer 2, a Ru adhesion layer 2, a TiN adhesion layer 2, and a TiO2 adhesion layer 2, with a thickness of 0.5 - 20 nm; the metal or nitride bottom electrode 3 is selected from any one of an Au bottom electrode 3, a W bottom electrode 3, an Ag bottom electrode 3, a Ti bottom electrode 3, an Al bottom electrode 3, a TiN bottom electrode 3, a Pt bottom electrode 3, a GaN bottom electrode 3, a Mo bottom electrode 3, and a Ta bottom electrode 3, with a thickness of 10 - 50 nm; Al 1-x Sc x N ferroelectric thin film 4, with a thickness of 5 - 50 nm; the metal or nitride top electrode 5 is selected from any one of an Au top electrode 5, a W top electrode 5, an Ag top electrode 5, a Ti top electrode 5, an Al top electrode 5, a TiN top electrode 5, a Pt top electrode 5, a GaN top electrode 5, a Mo top electrode 5, a Ta top electrode 5, and a Pd top electrode 5, with a thickness of 10 - 50 nm.

[0041] The ferroelectric diodes in the following examples are all prepared by the following method:

[0042] A method for preparing a ferroelectric diode based on a scandium-doped aluminum nitride thin film, comprising the following steps:

[0043] Step S1, deposit a layer of metal or oxide adhesion layer 2 on the substrate 1;

[0044] Step S2, deposit a layer of metal or nitride bottom electrode 3 on the adhesion layer 2

[0045] Step S3, deposit and form a layer of Al 1-x Sc x N ferroelectric thin film 4;

[0046] Step S4, coat photoresist on the Al 1-x Sc x N ferroelectric thin film 4, expose and develop;

[0047] Step S5, deposit a layer of top electrode 5 on the surface of the ferroelectric thin film 4;

[0048] Step S6, strip the deposited top electrode 5;

[0049] Example 1

[0050] In this example, the metal or oxide adhesion layer 2 is a titanium metal adhesion layer with a thickness of 5 nm; the metal or nitride bottom electrode 3 is a Pt electrode with a thickness of 40 nm; the Al 1-x Sc x N ferroelectric thin film 4 is Al 0.7 Sc0.3 N, with a thickness of 23 nm; the metal or nitride top electrode 5 is a TiN electrode with a thickness of 40 nm.

[0051] A method for preparing a ferroelectric diode based on scandium-doped aluminum nitride thin film, comprising the following steps:

[0052] Step S1, depositing a metal or oxide adhesion layer 2 on a silicon-based substrate 1;

[0053] Specifically, a titanium metal adhesion layer is grown by a DC magnetron sputtering process. The magnetron sputtering growth conditions are: DC sputtering power is 100 W, argon gas pressure is 3 mTorr, and the thickness is 5 nm.

[0054] Step S2, depositing a metal or nitride bottom electrode 3 on the titanium adhesion layer 2;

[0055] Specifically, a Pt bottom electrode 3 is grown by a DC magnetron sputtering process. The magnetron sputtering growth conditions are: DC sputtering power is 100 W, argon gas pressure is 3 mTorr, and the thickness is 40 nm.

[0056] Step S3, depositing a layer of Al 1-x Sc x N ferroelectric thin film 4 on the surface of the Pt bottom electrode 3;

[0057] Specifically, an Al 0.7 Sc 0.3 N thin film with a thickness of 23 nm is grown. The experimental parameters are adjusted, and co-sputtering is performed using an AlSc alloy target and a Sc target. The temperature is room temperature, the nitrogen-argon mixed gas pressure is set to 3 mTorr, and the nitrogen partial pressure is 80%. AlSc alloy target parameters: pulsed DC sputtering power is 300 W, pulse frequency is 100 kHz, Sc target parameters: RF sputtering power is 50 W. The AlSc alloy target and the Sc target are bombarded by argon ions ionized from argon gas, and an Al 0.7 Sc 0.3 N ferroelectric thin film 4 is deposited on the surface of the Pt bottom electrode 3, and the thickness is controlled to be 23 nm by controlling the growth time.

[0058] Step S4, coating photoresist on the Al 1-x Sc x N ferroelectric thin film 4, exposing and developing;

[0059] Specifically, negative photoresist 1500 is coated on the surface of the ferroelectric thin film 4, pre-baked at 150 °C for 2 min, post-baked at 120 °C for 2 min after exposure, soaked in the developer for 45 s for development, rinsed with deionized water, and dried with a nitrogen gun.

[0060] Step S5, depositing a layer of TiN top electrode 5 on the surface of the ferroelectric thin film 4;

[0061] Specifically, the TiN top electrode 5 is grown by a DC magnetron sputtering process. The magnetron sputtering growth conditions are as follows: the DC sputtering power is 100 W, the argon gas pressure is 1.15 mTorr, and the thickness is 40 nm.

[0062] Step S6: Strip the deposited top electrode 5.

[0063] Specifically, soak it in an acetone solution until the photoresist and the excess top electrode 5 layer fall off, then soak it in anhydrous ethanol to remove acetone, finally rinse it with deionized water, and dry it with a nitrogen gun.

[0064] Thus, a TiN / Al 0.7 Sc 0.3 N / Pt / SiO2 / Si device is obtained as a ferroelectric diode device.

[0065] The electrical properties of the device prepared in Example 1 are tested. It is found that when the applied electric field is 8 MV / cm, the remanent polarization value (2Pr) is 238 μC / cm 2 , showing a typical ferroelectric hysteresis loop, as Figure 2 shown by the solid line. The coercive electric field (polarization reversal electric field) is about 6 MV / cm, and the polarization current can be up to 130 A / cm 2 , and the leakage current is low, as Figure 2 shown by the dashed line. Figure 2 It shows that the device has excellent ferroelectric properties.

[0066] The device prepared in Example 1 is subjected to pulse testing and DC testing, and it is found that it has typical ferroelectric diode characteristics. After applying a positive voltage at the top electrode 5, the polarization is downward. Then, a DC sweep of ±4 V is performed on it, and the current changes from a low level to a high level, and the state changes from a negative-forward diode to a forward diode, as Figure 3 shown by the solid line. After applying a negative voltage at the top electrode 5, the polarization is upward. Then, a DC sweep of ±4 V is performed on it, and similar behavior can also be observed. The state changes from a forward diode to a negative-forward diode, as Figure 3 shown by the dashed line.

[0067] The device prepared in Example 1 is subjected to DC reliability testing. Through 350 cycles of DC sweeps, when the operating voltage is -4 V, the high and low resistance state distributions as Figure 4 shown are counted.

[0068] Comparative Example 1

[0069] The difference between this comparative example and Example 1 is that in step S3, the nitrogen partial pressure is 100%.

[0070] Comparative Example 2

[0071] The difference between this comparative example and Example 1 lies in that: in step S3, the nitrogen partial pressure is 60%.

[0072] Among the factors affecting whether the preparation can be carried out at room temperature, the nitrogen partial pressure has the greatest impact. By regulating the nitrogen partial pressure, the flow rates of nitrogen and argon are thus regulated. Mainly, the ions of argon bombard the target with high kinetic energy, causing the atoms in the alloy target to break away and react with nitrogen to form a thin film.

[0073] Examples 1, Comparative Example 1, and Comparative Example 2 were analyzed by X-ray diffraction (XRD) to evaluate the crystallization and orientation of the grains in the film out-of-plane. The results show that the crystallinity of the film in Example 1 is the highest, as Figure 5 shown (80 vol% N2, Example 1). In Comparative Example 1, a pure nitrogen environment was used during the growth process. Since there was no argon ion bombardment on the surface of the target, not many atoms could react, resulting in a low crystallinity of the formed film, as Figure 5 shown (100 vol% N2, Comparative Example 1); in Comparative Example 2, 60 vol% nitrogen content was used during the growth process. Excessive argon caused more atoms to be ionized, while the reactive nitrogen was relatively less and the reaction was incomplete, resulting in a low crystallinity of the film, as Figure 5 shown (60 vol% N2, Comparative Example 2).

[0074] Example 2

[0075] The adhesion layer 2 is a TiN adhesion layer 2 with a thickness of 10 nm; the bottom electrode 3 is a Au bottom electrode 3 with a thickness of 25 nm; the ferroelectric film 4 is Al 0.75 Sc 0.25 N with a thickness of 35 nm; the top electrode 5 is a Au top electrode 5 with a thickness of 25 nm. After testing, the performance is basically the same as that of the ferroelectric diode prepared in Example 1 and will not be repeated here.

[0076] Example 3

[0077] The adhesion layer 2 is a TiO2 adhesion layer 2 with a thickness of 0.5 nm; the bottom electrode 3 is a GaN bottom electrode 3 with a thickness of 50 nm; the ferroelectric film 4 is Al 0.9 Sc 0.1 N with a thickness of 50 nm; the top electrode 5 is a GaN top electrode 5 with a thickness of 50 nm. After testing, the performance is basically the same as that of the ferroelectric diode prepared in Example 1 and will not be repeated here.

[0078] Example 4

[0079] The adhesion layer 2 is a Si adhesion layer 2 with a thickness of 20 nm; the bottom electrode 3 is a W bottom electrode 3 with a thickness of 15 nm; the ferroelectric film 4 is Al 0.6 Sc 0.4N, with a thickness of 5 nm; the top electrode 5 is a W top electrode 5, with a thickness of 15 nm. After testing, the performance is basically the same as that of the ferroelectric diode prepared in Example 1, and will not be repeated here.

[0080] Example 5

[0081] The adhesion layer 2 is a Co adhesion layer 2, with a thickness of 3 nm; the bottom electrode 3 is an Au bottom electrode 3, with a thickness of 10 nm; the ferroelectric thin film 4 is Al 0.8 Sc 0.2 N, with a thickness of 40 nm; the top electrode 5 is an Au top electrode 5, with a thickness of 10 nm. After testing, the performance is basically the same as that of the ferroelectric diode prepared in Example 1, and will not be repeated here.

[0082] Example 6

[0083] The adhesion layer 2 is a Ru adhesion layer 2, with a thickness of 12 nm; the bottom electrode 3 is a Ta bottom electrode 3, with a thickness of 25 nm; the ferroelectric thin film 4 is Al 0.85 Sc 0.15 N, with a thickness of 33 nm; the top electrode 5 is an Ag top electrode 5, with a thickness of 20 nm. After testing, the performance is basically the same as that of the ferroelectric diode prepared in Example 1, and will not be repeated here.

[0084] In the above description, no detailed description is made of the technical details such as the patterning and etching of each layer. However, those skilled in the art should understand that various technical means can be used to form layers, regions, etc. of the required shapes. In addition, in order to form the same structure, those skilled in the art can also design methods that are not exactly the same as the methods described above. In addition, although the above embodiments are described separately, this does not mean that the measures in each embodiment cannot be used advantageously in combination.

[0085] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. Obviously, those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A preparation method of a ferroelectric diode based on scandium-doped aluminum nitride thin film, characterized in that, The ferroelectric diode is formed by sequentially laminating a substrate (1), an adhesion layer (2), a bottom electrode (3), a ferroelectric thin film (4), and a top electrode (5). Among them, the ferroelectric thin film (4) is an Al 1-x Sc x N ferroelectric thin film; The ferroelectric diode described above is prepared by the following steps: S1: A adhesion layer (2) is grown on a substrate (1) by magnetron sputtering; S2: A bottom electrode (3) is grown on the adhesion layer (2) by magnetron sputtering; S3: At room temperature, a ferroelectric thin film (4) is grown on the bottom electrode (3) by co-sputtering; S4: A photoresist is coated on the ferroelectric thin film (4) and exposed and developed; S5: A top electrode (5) is grown on the exposed and developed ferroelectric thin film (4) by magnetron sputtering; S6: Lift-off is performed to obtain the ferroelectric diode described above.

2. The preparation method of a ferroelectric diode based on a scandium-doped aluminum nitride thin film according to claim 1, characterized in that, The substrate (1) described above is a silicon-based substrate; the adhesion layer (2) is a metal adhesion layer or an oxide adhesion layer; the bottom electrode (3) is a metal bottom electrode or a nitride bottom electrode; the top electrode (5) is a metal bottom electrode or a nitride bottom electrode.

3. The preparation method of a ferroelectric diode based on a scandium-doped aluminum nitride thin film according to claim 2, characterized in that, The adhesion layer (2) is selected from any one of an Au adhesion layer, a Co adhesion layer, a Si adhesion layer, a Ti adhesion layer, a Cr adhesion layer, a Ru adhesion layer, a TiN adhesion layer, and a TiO2 adhesion layer, and has a thickness of 0.5 to 20 nm; the bottom electrode (3) is selected from any one of an Au bottom electrode, a W bottom electrode, an Ag bottom electrode, a Ti bottom electrode, an Al bottom electrode, a TiN bottom electrode, a Pt bottom electrode, a GaN bottom electrode, a Mo bottom electrode, and a Ta bottom electrode, and has a thickness of 10 to 50 nm; the ferroelectric thin film (4) is an Al 1-x Sc x ScN ferroelectric thin film, where x = 0.1 to 0.4, and has a thickness of 5 to 50 nm; the top electrode (5) is selected from any one of an Au top electrode, a W top electrode, an Ag top electrode, a Ti top electrode, an Al top electrode, a TiN top electrode, a Pt top electrode, a GaN top electrode, a Mo top electrode, a Ta top electrode, and a Pd top electrode, and has a thickness of 10 to 50 nm.

4. The preparation method of a ferroelectric diode based on a scandium-doped aluminum nitride thin film according to claim 1, characterized in that, In step S1, the adhesion layer (2) is grown on the substrate (1) by DC magnetron sputtering.

5. The preparation method of a ferroelectric diode based on a scandium-doped aluminum nitride thin film according to claim 1, wherein, In step S2, the bottom electrode (3) is grown on the adhesion layer (2) by DC magnetron sputtering.

6. The preparation method of a ferroelectric diode based on a scandium-doped aluminum nitride thin film according to claim 1, wherein In step S3, the co-sputtering is as follows: in a nitrogen-argon mixed atmosphere, co-sputtering is performed using an AlSc alloy target and a Sc target. Among them, the AlSc alloy target uses a pulsed DC magnetron sputtering power of 300 W, the pulse frequency is 100 kHz, and the Sc target uses a RF magnetron sputtering power of 50 W; the pressure of the nitrogen-argon mixed atmosphere is 3 mTorr, and the nitrogen partial pressure is 80%.

7. The preparation method of a ferroelectric diode based on a scandium-doped aluminum nitride thin film according to claim 1, wherein, In step S4, a negative photoresist is coated on the surface of the ferroelectric thin film (4) and heated at 150 °C for 2 min, exposed at 120 °C for 2 min, soaked in a developer for 45 s for development, then washed with deionized water, and dried with an inert gas.

8. The preparation method of a ferroelectric diode based on a scandium-doped aluminum nitride thin film according to claim 1, characterized in that, In step S5, the top electrode (5) is grown on the exposed and developed ferroelectric thin film (4) by DC magnetron sputtering.

9. The preparation method of a ferroelectric diode based on a scandium-doped aluminum nitride thin film according to claim 1, wherein, In step S6, the lift-off includes: soaking in acetone and absolute ethanol in sequence, then washed with deionized water, and dried with an inert gas.

10. Application of a ferroelectric diode prepared by the method according to any one of claims 1 to 9 in a ferroelectric memory.

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