Anti-ferroelectric capacitor and preparation method thereof

Abstract

The invention provides a preparation method of an anti-ferroelectric capacitor. The preparation method comprises the following steps: firstly, depositing a conductive material on a substrate as a lower electrode layer; then in a protective atmosphere containing oxygen, an anti-ferroelectric layer is formed through magnetron sputtering, the material of the anti-ferroelectric layer is zirconium oxide or hafnium zirconium oxide, and the oxygen introduction amount of the oxygen is 0.2-0.6 sccm; and finally, depositing a conductive material on the surface of the anti-ferroelectric layer as an upper electrode layer to obtain the anti-ferroelectric capacitor. The invention further provides the anti-ferroelectric capacitor obtained by the preparation method.

Description

Technical Field

[0001] The present disclosure relates to the fields of semiconductors and energy storage technologies, and particularly to an antiferroelectric capacitor and a method for preparing the same. Background Art

[0002] With the rapid development of renewable energy and the widespread application of portable electronic devices, the demand for high-performance energy storage materials in the fields of energy storage and conversion is increasing continuously. Although traditional perovskite dielectric capacitors (such as barium titanate (BaTiO3)-based materials) have a high dielectric constant, they have problems such as a low breakdown field strength, a large amount of leakage current, and reliability issues, and it is difficult to be compatible with the CMOS process. Therefore, it is urgent to develop new materials to meet the requirements of next-generation energy storage devices.

[0003] In recent years, antiferroelectric materials have shown excellent energy storage performance due to their unique double hysteresis loop characteristics and electric field-induced phase transition behavior. Among them, hafnium zirconium oxide (HZO)-based antiferroelectric materials are considered to be one of the most promising next-generation energy storage dielectric materials because of their high dielectric constant, low remanent polarization, high breakdown field strength, etc., and compatibility with CMOS technology. Research shows that by regulating the composition, thickness, and grain size of hafnium zirconium oxide thin films, their energy storage density can be significantly improved. However, with the increase in energy storage density, a higher electric field strength usually needs to be applied, which will lead to an increase in internal defects and leakage current in the material, and further cause an increase in energy loss (LOSS) and a decrease in energy storage efficiency (η). This contradiction seriously restricts the application of antiferroelectric materials in high-performance energy storage devices.

[0004] Therefore, how to effectively reduce energy loss and improve energy storage efficiency while increasing the energy storage density has become a key technical problem to be solved urgently in the field of preparing antiferroelectric capacitors. Summary of the Invention

[0005] In view of this, to solve at least one technical problem in the related art and other aspects, the present disclosure provides a method for preparing an antiferroelectric capacitor, which includes: First, depositing a conductive material on a substrate as a lower electrode layer; then, in a protective atmosphere containing oxygen, forming an antiferroelectric layer by magnetron sputtering, wherein the material of the antiferroelectric layer is zirconium oxide or hafnium zirconium oxide, and the oxygen flow rate is 0.2-0.6 sccm; finally, depositing a conductive material on the surface of the antiferroelectric layer as an upper electrode layer to obtain an antiferroelectric capacitor.

[0006] According to an embodiment of the present disclosure, the ratio of the o / t phase in the antiferroelectric layer is 0-0.49.

[0007] According to an embodiment of the present disclosure, the oxygen component content in the antiferroelectric layer is 63.0% - 66.5%.

[0008] According to an embodiment of the present disclosure, during the magnetron sputtering process, hafnium oxide and zirconium oxide are used as sputtering targets. Among them, the sputtering power of zirconium oxide is 110 W, and the sputtering power of hafnium oxide is 0 - 50 W.

[0009] According to an embodiment of the present disclosure, the content of zirconium element in the antiferroelectric layer is 35% - 100%.

[0010] According to an embodiment of the present disclosure, the aforementioned preparation method further includes: annealing the antiferroelectric capacitor at 400 - 700 °C for 30 s - 1 min.

[0011] According to an embodiment of the present disclosure, the conductive material is independently selected from at least one of tungsten, iridium, rubidium, platinum, palladium, rubidium oxide, tantalum nitride, titanium nitride, and highly conductive silicon.

[0012] In another aspect of the present disclosure, an antiferroelectric capacitor obtained by the aforementioned preparation method is also proposed. The antiferroelectric capacitor sequentially includes a lower electrode layer, an antiferroelectric layer, and an upper electrode layer from bottom to top. Among them, the ratio of the o / t phase in the antiferroelectric layer is 0.49 - 0.6.

[0013] According to an embodiment of the present disclosure, the breakdown voltage of the antiferroelectric capacitor is 3.88 V - 4.72 V.

[0014] According to an embodiment of the present disclosure, the energy storage density of the antiferroelectric capacitor is 23.13 - 67.34 J / cm 3 , and the efficiency of the antiferroelectric capacitor is 0.39 - 1.

[0015] According to an embodiment of the present disclosure, by means of the magnetron sputtering process and introducing 0.2 - 0.6 sccm of oxygen therein, the oxygen vacancy concentration and the ratio of hafnium and zirconium elements in the antiferroelectric layer (zirconium oxide or hafnium zirconium oxide) can be precisely regulated. An appropriate amount of oxygen fills the oxygen vacancy defects in the hafnium zirconium oxide thin film, reduces the leakage current, thereby reducing the energy loss (LOSS), and also maintains a relatively high breakdown field strength and energy storage density (ESD) of the hafnium zirconium oxide thin film. At the same time, adjusting the ratio of hafnium and zirconium elements by magnetron sputtering in a protective atmosphere containing oxygen helps to regulate the phase composition of the antiferroelectric layer and form a high-quality antiferroelectric layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the hysteresis curve diagram of the antiferroelectric hafnium zirconium oxide material in the embodiment of the present disclosure;

[0017] Figure 2 is the structural schematic diagram of the antiferroelectric capacitor in the embodiment of the present disclosure;

[0018] Figure 3 is the X-ray diffraction pattern of the antiferroelectric layer in the antiferroelectric capacitor prepared under different oxygen flow rates in Embodiment 1 of the present disclosure;

[0019] Figure 4 It is a columnar comparison chart of the contents of the o-phase and t-phase in the antiferroelectric layer of the antiferroelectric capacitors prepared under different oxygen flow conditions in Embodiment 1 of the present disclosure;

[0020] Figure 5 It is a columnar comparison chart of the breakdown voltages of the antiferroelectric capacitors prepared under different oxygen flow conditions in Embodiment 1 of the present disclosure;

[0021] Figure 6 It is a columnar comparison chart of the leakage currents of the antiferroelectric capacitors prepared under different oxygen flow conditions in Embodiment 1 of the present disclosure;

[0022] Figure 7 It is an X-ray diffraction pattern of the antiferroelectric layer in the antiferroelectric capacitors with different hafnium-zirconium element content ratios in Embodiment 2 of the present disclosure.

[0023] In the description of the present disclosure, the meanings of the reference numerals are as follows:

[0024] 1 - Substrate; 2 - Lower electrode layer; 3 - Antiferroelectric layer; 4 - Upper electrode layer. Detailed implementation manners

[0025] To make the objectives, technical solutions and advantages of the present disclosure clearer and more understandable, the following further describes the present disclosure in detail with reference to specific embodiments and the accompanying drawings.

[0026] In the ranges disclosed in the present disclosure, the endpoints and any values of the ranges are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present disclosure.

[0027] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "including", "comprising", etc. used herein indicate the presence of the described features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0028] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used here should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0029] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in this disclosure shall have the ordinary meanings understood by those with ordinary skills in the field to which this disclosure pertains. If descriptions such as "first", "second", etc. are involved throughout the text, these "first", "second", etc. descriptions are only used to distinguish similar objects, and cannot be construed as indicating or implying their relative importance, sequence, or implicitly specifying the quantity of the indicated technical features. It should be understood that the data described by "first", "second", etc. can be interchanged under appropriate circumstances.

[0030] Throughout the accompanying drawings, the same elements are denoted by the same or similar reference numerals. When it may cause confusion in understanding this disclosure, conventional structures or configurations will be omitted. Also, the shapes, sizes, and positional relationships of the components in the figures do not reflect the actual sizes, proportions, and actual positional relationships. Additionally, in this disclosure, any reference signs located between parentheses should not be construed as limiting this disclosure.

[0031] Similarly, in order to streamline this disclosure and assist in understanding one or more of the various disclosed aspects, in the above description of the exemplary embodiments of this disclosure, the various features of this disclosure are sometimes grouped together into a single embodiment, figure, or description thereof. Descriptions with reference terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this disclosure. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0032] In addition, terms such as "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Therefore, features defined with "first", "second" can explicitly or implicitly include one or more of such features. In the description of this disclosure, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0033] Furthermore, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or is unable to be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this disclosure.

[0034] Hafnium zirconium oxide (hereinafter may be abbreviated as Hf x Zr 1-x(Hf1-xZrx)O2 (where 0 < x < 0.7) materials have become a hot topic of extensive attention and research due to their excellent scalability and high compatibility of the preparation process with the CMOS process. Compared with ferroelectric hafnium zirconium oxide, antiferroelectric hafnium zirconium oxide has a remanent polarization (Pr) of 0 and lower energy loss. At the same time, its devices are less affected by the wake-up effect and fatigue effect, which makes it show more prominent application advantages in the energy storage field. It is generally believed that the antiferroelectric property of hafnium oxide (HfO2)-based materials is caused by the t-phase with the space group P42 / nmc in the thin film, and its relative dielectric constant ranges from 35 to 70.

[0035] Although antiferroelectric hafnium zirconium oxide materials have many advantages in the energy storage field, increasing the energy storage density (ESD) usually requires applying a higher electric field strength, which will increase its energy loss (LOSS) and decrease the efficiency (η), making it difficult to balance the two. This problem has always been the main bottleneck restricting the development of antiferroelectric hafnium zirconium oxide in the energy storage field.

[0036] To solve the above problems, various methods have been tried in related technologies, such as doping modification, interface engineering, and stress regulation, etc. It has been found during the implementation of this disclosure that introducing an appropriate amount of oxygen during the thin film deposition process is considered an effective means. The appropriate amount of oxygen can fill the oxygen vacancies in the thin film and reduce the leakage current, thereby reducing the energy loss. However, the introduction amount of oxygen needs to be precisely controlled. Excessive oxygen will lead to a decrease in the crystallinity of the thin film and instead reduce the energy storage performance.

[0037] This disclosure aims to provide a new method for preparing an antiferroelectric capacitor. By optimizing the oxygen flow rate in the magnetron sputtering process, the controllable adjustment of oxygen vacancies in the hafnium zirconium oxide thin film is realized, so as to effectively reduce the energy loss while increasing the energy storage density, and improve the energy storage efficiency, providing new ideas for the development of high-performance energy storage devices.

[0038] In this disclosure, the meanings of the terms "o-phase", "t-phase", and "m-phase" are the phases in antiferroelectric materials (such as zirconium oxide (ZrO2) or hafnium zirconium oxide (Hf x Zr 1-xIn (O2)), the o-phase, t-phase, and m-phase represent the orthorhombic phase, tetragonal phase, and monoclinic phase, respectively. The o-phase is one of the common crystal structures in ferroelectric materials, with orthorhombic symmetry and exhibiting typical ferroelectricity. Therefore, the presence of the o-phase increases the window of the antiferroelectric P-E hysteresis loop, resulting in an increase in the remanent polarization, thereby reducing the energy storage density and efficiency. The t-phase is another important crystal structure, with tetragonal symmetry and showing antiferroelectricity. The presence of the t-phase can enhance the polarization intensity of the material and increase the dielectric constant of the material. Therefore, by regulating the ratio of the o / t phase, the antiferroelectric properties of the HZO thin film can be improved. The m-phase usually does not have ferroelectricity or antiferroelectricity. Therefore, in energy storage applications, the presence of the m-phase may reduce the polarization intensity and energy storage performance of the material. Excessive m-phase will lead to a decrease in the dielectric constant of the material, thereby affecting its energy storage density (ESD).

[0039] In the present disclosure, the meaning of the term "oxygen vacancy" is as follows: Oxygen vacancy is a common defect in antiferroelectric materials, which will affect the conductivity, dielectric property, and phase transition behavior of the materials.

[0040] Before the implementation of the present disclosure, an optimized method for increasing the energy storage density by increasing the breakdown voltage of the antiferroelectric hafnium zirconium oxide material was theoretically verified.

[0041] Figure 1 It is the P-E hysteresis curve diagram of the antiferroelectric hafnium zirconium oxide material in the embodiment of the present disclosure.

[0042] As Figure 1 shown, the P-E hysteresis curve includes a charging process and a discharging process with the change of voltage.

[0043] Specifically, the energy storage density (ESD) is the integral of the applied voltage from the remanent polarization (P r ) to the maximum polarization (P max ), as shown in the following formula (1):

[0044] (1);

[0045] where E is the electric field strength and P is the polarization intensity. Increasing the breakdown voltage means that the material can withstand a higher electric field strength (E), thereby achieving a larger polarization intensity (P) at a higher electric field, and thus increasing the energy storage density.

[0046] The total energy storage density (W Total ) is the integral of the applied voltage from 0 to the maximum polarization (P max ), as shown in the following formula (2):

[0047] (2);

[0048] The energy loss (LOSS) is the total energy storage density (W Total ) minus the energy storage density ( );

[0049] The efficiency (η) is the ratio of the energy storage density ( ) to the total energy storage density (W Total ), as shown in Equation (3) below:

[0050] (3).

[0051] Among them, increasing the breakdown voltage can reduce the leakage current and energy loss of the material under high electric fields, thereby improving the energy storage efficiency (η).

[0052] First, for increasing the breakdown voltage, Figure 1 The dark blue part in it is the part where the energy storage density increases, and at the same time the efficiency part increases; secondly, the energy loss decreases. On the one hand, it can increase the energy storage density, and on the other hand, it can ensure that W Total remains unchanged, thereby increasing the efficiency (η). Finally, by regulating the oxygen flow and the hafnium zirconium ratio, the energy storage density ESD and efficiency are improved. That is, by increasing the breakdown voltage of the antiferroelectric hafnium zirconium oxide material, the energy storage density (ESD) and the energy storage efficiency (η) can be significantly increased. Optimizing the material composition can regulate the phase ratio and increase the t-phase component. These optimization measures not only improve the energy storage performance of the material, but also enhance the reliability and stability of the device, providing important technical support for the development of high-performance energy storage devices.

[0053] The present disclosure provides a method for preparing an antiferroelectric capacitor, the preparation method comprising: first, depositing a conductive material on a substrate as a lower electrode layer; then, in a protective atmosphere containing oxygen, forming an antiferroelectric layer by magnetron sputtering, wherein the material of the antiferroelectric layer is zirconium oxide or hafnium zirconium oxide (Hf x Zr 1-x O2), and the oxygen flow rate is 0.2 - 0.6 sccm; finally, depositing a conductive material on the surface of the antiferroelectric layer as an upper electrode layer to obtain an antiferroelectric capacitor.

[0054] According to an embodiment of the present disclosure, through the process of magnetron sputtering and introducing 0.2 - 0.6 sccm of oxygen therein, the oxygen vacancy concentration and the hafnium zirconium element content ratio in the antiferroelectric layer (zirconium oxide or hafnium zirconium oxide) can be precisely regulated. An appropriate amount of oxygen fills the oxygen vacancy defects in the hafnium zirconium oxide thin film, reduces the leakage current, thereby reducing the energy loss (LOSS), and also maintains a relatively high breakdown field strength and energy storage density (W ESD). Meanwhile, magnetron sputtering is carried out in a protective atmosphere containing oxygen to adjust the content of hafnium and zirconium elements, which helps to regulate the phase composition of the antiferroelectric layer and form a high-quality antiferroelectric layer.

[0055] According to an embodiment of the present disclosure, the ratio of the o / t phase in the antiferroelectric layer is 0 - 0.49.

[0056] According to an embodiment of the present disclosure, an appropriate ratio of the o phase and the t phase can optimize the microstructure of the material, reduce defects and stress concentration, thereby increasing the breakdown field strength. The o phase and the t phase are two important crystal structures in the antiferroelectric material, corresponding to ferroelectricity and antiferroelectric behavior respectively. Verified by the embodiments of the present disclosure, by regulating the o / t phase ratio (such as 0 - 0.49).

[0057] According to an embodiment of the present disclosure, the oxygen component content in the antiferroelectric layer is 63.0% - 66.5%.

[0058] According to an embodiment of the present disclosure, regulating the oxygen flow rate is the key means to adjust the oxygen component content in the antiferroelectric layer. During magnetron sputtering, introducing oxygen can fill the oxygen vacancies in the antiferroelectric layer and adjust the oxygen component content. Verified by the embodiments of the present disclosure, by controlling the oxygen component content within the range of 63.0% - 66.5%, the crystal structure of the antiferroelectric layer can be optimized, the energy loss can be reduced, the breakdown field strength can be increased, and the interface quality can be enhanced. An appropriate amount of oxygen component helps to form a high-quality antiferroelectric t phase and optimize the ferroelectric-antiferroelectric phase transition behavior of the material. The crystallization quality and dielectric properties of the ferroelectric layer are optimized while maintaining good antiferroelectricity.

[0059] In some specific embodiments, when the oxygen component is too low (<63.0%), there are more oxygen vacancies in the material, resulting in an increase in leakage current and an increase in energy loss (LOSS). When the oxygen component is too high (>66.5%): Excessive oxygen may cause the formation of amorphous phases or other impurity phases in the material, reducing the antiferroelectricity. Too much oxygen will also increase interface defects, affecting the stability and reliability of the material. When the oxygen component is within the range of 63.0% - 66.5%, the oxygen vacancies in the material are effectively filled, and the leakage current and energy loss are significantly reduced.

[0060] In some specific embodiments, changing the oxygen flow rate to regulate the oxygen vacancy concentration in the antiferroelectric layer hafnium zirconium oxide thin film to increase the antiferroelectricity mainly includes three aspects: first, under oxygen-deficient conditions, there will be more oxygen vacancies in the hafnium zirconium oxide thin film, and applying a smaller voltage will cause the device to be broken down. Therefore, by regulating the concentration of oxygen vacancies, the breakdown voltage of the antiferroelectric layer can be increased; secondly, the presence of oxygen vacancies will increase the transformation from the t phase to the ferroelectric o phase, which is beneficial to the generation of ferroelectricity (increase in the precursor t phase), and fewer oxygen vacancies can inhibit the occurrence of this process; finally, in the process of sputtering the hafnium zirconium oxide thin film, oxygen vacancies will inhibit grain growth and the formation of the m phase, thereby increasing the proportion of the antiferroelectric o phase, and regulating the oxygen vacancies can achieve the regulation of the t phase proportion.

[0061] According to an embodiment of the present disclosure, in the magnetron sputtering process, hafnium oxide and zirconium oxide are used as sputtering targets, wherein the sputtering power of zirconium oxide is 110W, and the sputtering power of hafnium oxide is 0-50W.

[0062] According to the embodiments of the present disclosure, regulating the sputtering power is a key means to regulate the proportion of hafnium-zirconium components in the hafnium-zirconium-oxide film. The sputtering power of zirconium oxide is fixed at 110W, which ensures a stable supply of zirconium (Zr) components. The sputtering power of hafnium oxide is adjusted within the range of 0-50W to control the content of the hafnium (Hf) component. The higher the power, the faster the sputtering rate of hafnium and the higher the hafnium content in the film. By fixing the sputtering power of zirconium oxide (110W) and adjusting the sputtering power of hafnium oxide (0-50W), the proportion of hafnium-zirconium in the film can be precisely controlled.

[0063] According to the embodiments of the present disclosure, the magnetron sputtering process is used to grow the hafnium zirconium oxide film, which can achieve high-quality film growth and precise control of the composition. By changing the oxygen flux and the Hf / Zr ratio during the magnetron sputtering process, the antiferroelectric properties of the hafnium zirconium oxide film are optimized, which is also a low-cost and efficient optimization method, and the regulation can be completed simply and efficiently during the process. Without the need to dope other impurities or change the process conditions, the energy storage density (ESD) and efficiency (η) of the antiferroelectric layer hafnium zirconium oxide film can be easily improved.

[0064] According to embodiments of the present disclosure, pure HfO2 and ZrO2 are mainly in the t-phase, but lack significant ferroelectric (FE) or antiferroelectric (AFE) properties. Therefore, the antiferroelectricity of hafnium zirconium oxide thin films is not determined solely by the t-phase. Trace doping can significantly enhance the ferroelectric / antiferroelectric (FE / AFE) properties of hafnium zirconium oxide thin films, which may be closely related to the presence of the antipolar o-I phase in the thin films. In hafnium zirconium oxide thin films, due to the high Hf content, the ferroelectric hysteresis curve window is large, showing a high energy loss (LOSS). In order to reduce the energy loss (LOSS) and further improve the energy storage density (ESD) and efficiency (η), it is necessary to suppress the ferroelectric behavior of hafnium zirconium oxide thin films by optimizing the material composition and phase structure, so that it more significantly exhibits antiferroelectricity.

[0065] According to embodiments of the present disclosure, the content of zirconium element in the antiferroelectric layer is 35% - 100%.

[0066] According to embodiments of the present disclosure, the foregoing preparation method further includes: annealing the antiferroelectric capacitor at 400 - 700 °C for 30 s - 1 min.

[0067] According to embodiments of the present disclosure, the annealing treatment can promote the transformation of the antiferroelectric layer (such as zirconia or hafnium zirconium oxide) from an amorphous state or a partially crystalline state to a highly crystalline state. At an appropriate annealing temperature (400 - 700 °C), the ratio of the orthorhombic phase (o-phase) and the tetragonal phase (t-phase) in the antiferroelectric material can be optimized. Further, the annealing treatment can also repair the interface defects between the antiferroelectric layer and the upper and lower electrodes, improving the interface quality. Good interface contact can reduce the interface resistance and improve the overall performance of the device. The annealing time is controlled within 30 s - 1 min, avoiding the negative impact of long-time high-temperature treatment on the material properties.

[0068] According to embodiments of the present disclosure, the conductive material is independently selected from at least one of tungsten, iridium, rubidium, platinum, palladium, rubidium oxide, tantalum nitride, titanium nitride, and highly conductive silicon.

[0069] Figure 2 It is a schematic diagram of the structure of the antiferroelectric capacitor in the embodiments of the present disclosure.

[0070] In another aspect of the present disclosure, an antiferroelectric capacitor obtained by the foregoing preparation method is also proposed. As Figure 2 shown, the antiferroelectric capacitor sequentially includes a lower electrode layer 2, an antiferroelectric layer 3, and an upper electrode layer 4 from bottom to top, wherein the ratio of the o / t phase in the antiferroelectric layer 3 is 0 - 0.49.

[0071] According to embodiments of the present disclosure, the breakdown voltage of the antiferroelectric capacitor is 3.88 V - 4.72 V.

[0072] According to an embodiment of the present disclosure, the energy storage density of the antiferroelectric capacitor is 23.13 - 67.34 J / cm 3 , and the efficiency of the antiferroelectric capacitor is 0.39 - 1.

[0073] According to an embodiment of the present disclosure, the antiferroelectric capacitor proposed by the present disclosure realizes high energy storage density, low energy loss, high breakdown field strength and excellent phase change reversibility by controlling the o / t phase ratio in the antiferroelectric layer within the range of 0 - 0.49. This design not only improves the performance and reliability of the device, but also provides important theoretical support for its application in the field of high-performance energy storage. Its excellent performance is suitable for high-performance energy storage devices, such as pulsed power systems, new energy storage systems and portable electronic devices, etc.

[0074] It should be noted that the described embodiments are only a part of the embodiments of the present disclosure, rather than all embodiments. Based on the embodiments in the present disclosure, other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present disclosure.

[0075] Example 1

[0076] Taking a 4-inch Si / SiO2 wafer as a polysilicon substrate, TiN is deposited on the polysilicon substrate by an ion beam sputtering process as the upper electrode layer, and the thickness of the upper electrode layer is 40 nm.

[0077] Then, a hafnium zirconium oxide thin film is deposited as the antiferroelectric layer by a magnetron sputtering process in an oxide deposition chamber. Among them, the magnetron sputtering target is HfO2 and ZrO2, the sputtering power of the HfO2 source is 50 W, and the power of the ZrO2 source is 110 W. Argon is introduced into the chamber at 20 standard cubic centimeters per minute (sccm), and the oxygen rates are set to 0 sccm, 0.2 sccm, 0.4 sccm, and 0.6 sccm respectively. The growth thickness of the hafnium zirconium oxide thin film is set to 10 nm under different oxygen flow rates.

[0078] Photolithography is performed on the hafnium zirconium oxide thin film antiferroelectric layer device after the thin film is grown. TiN is deposited on the antiferroelectric layer by an ion beam sputtering process as the upper electrode layer, and the thickness of the upper electrode layer is 40 nm to obtain an antiferroelectric capacitor.

[0079] Furthermore, in an N2 atmosphere, the antiferroelectric capacitor is subjected to rapid thermal annealing, where the thermal annealing temperature is 500 °C and the thermal annealing time is 30 s to crystallize the hafnium zirconium oxide thin film.

[0080] Measure the oxygen component content and phase composition of the hafnium zirconium oxide thin film ferroelectric layer under different oxygen flow rates. The oxygen flow mainly regulates the ratio of the o / t phase. Therefore, the main focus is on the ratio value between the o / t phases. By performing XRD analysis on hafnium zirconium oxide thin films with different oxygen flow rates, and then performing peak fitting on the XRD images based on the positions of the t(101) and o(111) peaks, the ratio of the o / t phases is obtained according to the area ratio. The results are recorded in Table 1 below:

[0081] Table 1

[0082]

[0083] Figure 3 is the X-ray diffraction pattern of the antiferroelectric layer in the antiferroelectric capacitor prepared under different oxygen flow rate conditions in Example 1 of the present disclosure; Figure 4 is the column comparison chart of the o-phase and t-phase contents of the antiferroelectric layer in the antiferroelectric capacitor prepared under different oxygen flow rate conditions in Example 1 of the present disclosure.

[0084] As Figure 3 、 4 and as shown in Table 1, after adjusting the oxygen flow rate, the ratio of the t-phase in the hafnium zirconium oxide thin film is significantly increased.

[0085] Furthermore, perform electrical property tests on its breakdown voltage and leakage current.

[0086] Figure 5 is the column comparison chart of the breakdown voltages of the antiferroelectric capacitors prepared under different oxygen flow rate conditions in Example 1 of the present disclosure; Figure 6 is the column comparison chart of the leakage currents of the antiferroelectric capacitors prepared under different oxygen flow rate conditions in Example 1 of the present disclosure.

[0087] As Figure 5 、 6 shown, for the measurement of the breakdown voltage, since there will be fluctuations in the measurement of the breakdown voltage, 12 measurements of the breakdown voltage are performed on the hafnium zirconium oxide thin films under four oxygen flow rate conditions. The actual measurement results remove the highest and lowest values, and then perform mathematical statistical analysis to draw its normal distribution curve, so as to obtain the breakdown voltage values under different oxygen flow conditions as: 3.88V, 4.72V, 4.49V, 4.29V. By changing the oxygen vacancy content in the hafnium zirconium oxide thin film by regulating the oxygen flow rate during the magnetron sputtering process, the breakdown voltage of the antiferroelectric layer can be increased, thereby achieving an increase in the energy storage density (ESD) and efficiency (η). It can be seen that for changing the oxygen flow rate, the improvement effect of the breakdown voltage is very obvious.

[0088] Example 2

[0089] Under the oxygen flow conditions in Example 1, adjust the ratio of Hf and Zr to adjust Hfx Zr 1-x The content of the t-phase in the ZrO₂ film.

[0090] Using a 4-inch Si / SiO₂ wafer as the polysilicon substrate, TiN is deposited on the polysilicon substrate as the upper electrode layer through an ion beam sputtering process, and the thickness of the upper electrode layer is 40 nm.

[0091] Then, a hafnium zirconium oxide film is deposited as the antiferroelectric layer through a magnetron sputtering process in an oxide deposition chamber. Among them, the magnetron sputtering target is HfO₂ and ZrO₂. In order to change the Hf / Zr concentration between different samples, the ZrO₂ source power is kept constant at 110 W, and the HfO₂ source power varies from 0 - 50 W. 20 standard cubic centimeters per minute (sccm) of argon gas is introduced into the chamber, and the oxygen rate is set at 0.2 sccm. It is set that the growth thickness of the hafnium zirconium oxide film is 10 nm under different oxygen throughputs.

[0092] Lithography is performed on the hafnium zirconium oxide film antiferroelectric layer device after film growth. TiN is deposited on the antiferroelectric layer through an ion beam sputtering process as the upper electrode layer, and the thickness of the upper electrode layer is 40 nm to obtain an antiferroelectric capacitor.

[0093] Furthermore, in an N₂ atmosphere, the antiferroelectric capacitor is subjected to rapid thermal annealing, where the thermal annealing temperature is 500 °C and the thermal annealing time is 30 s to crystallize the hafnium zirconium oxide film.

[0094] Measure the electrical properties of the hafnium zirconium oxide film antiferroelectric layer under different oxygen throughputs and different hafnium zirconium element content ratios (Hf / Zr ratio), and the results are recorded in Table 2 below:

[0095] Table 2

[0096]

[0097] Figure 7 It is the X-ray diffraction pattern of the antiferroelectric layer in the antiferroelectric capacitors with different hafnium zirconium ratios in Example 2 of the present disclosure.

[0098] As Figure 7 shown in and Table 2, by changing the power of the HfO₂ and ZrO₂ sources during the magnetron sputtering process to regulate the Hf / Zr ratio in the hafnium zirconium oxide film, and then regulating the phase ratio of the hafnium zirconium oxide film in the antiferroelectric layer, the formation of the m-phase can be effectively inhibited. This process significantly reduces the energy loss and makes the hafnium zirconium oxide film more significantly exhibit antiferroelectric characteristics. Further, by jointly regulating the oxygen throughput and the Hf / Zr ratio, the ferroelectric / antiferroelectric performance of the hafnium zirconium oxide film can be simply, rapidly, significantly and comprehensively improved.

[0099] The specific embodiments described above further elaborate on the objectives, technical solutions, and beneficial effects of the present disclosure. It should be understood that the above are only specific embodiments of the present disclosure and are not used to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

1. A method for preparing an antiferroelectric capacitor, characterized in that, The preparation method includes: Depositing a conductive material on a substrate as a lower electrode layer; Forming an antiferroelectric layer by magnetron sputtering in an atmosphere containing oxygen, wherein the material of the antiferroelectric layer is zirconia or hafnium zirconium oxide, and the oxygen flow rate is 0.2 - 0.6 sccm; Depositing a conductive material on the surface of the antiferroelectric layer as an upper electrode layer to obtain an antiferroelectric capacitor.

2. The preparation method according to claim 1, wherein The proportion of the o / t phase in the antiferroelectric layer is 0 - 0.

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3. The preparation method according to claim 1, wherein The oxygen component content in the antiferroelectric layer is 63.0% - 66.5%.

4. The preparation method according to claim 1, wherein, During the magnetron sputtering process, hafnium oxide and zirconia are used as sputtering targets, wherein, The sputtering power of the zirconia is 110 W, and the sputtering power of the hafnium oxide is 0 - 50 W.

5. The preparation method according to claim 4, wherein, The content of zirconium element in the antiferroelectric layer is 35% - 100%.

6. The preparation method according to claim 1 further comprises: Annealing the antiferroelectric capacitor at 400 - 700 °C for 30 s - 1 min.

7. The preparation method according to claim 1, wherein, The conductive materials are independently selected from at least one of tungsten, iridium, rubidium, platinum, palladium, rubidium oxide, tantalum nitride, titanium nitride, and highly conductive silicon.

8. An antiferroelectric capacitor obtained by the preparation method according to any one of claims 1-7, characterized in that, The antiferroelectric capacitor includes a lower electrode layer, an antiferroelectric layer, and an upper electrode layer in sequence from bottom to top, wherein the proportion of the o / t phase in the antiferroelectric layer is 0 - 0.

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9. The antiferroelectric capacitor according to claim 8, wherein, The breakdown voltage of the antiferroelectric capacitor is 3.88 V - 4.72 V.

10. The antiferroelectric capacitor according to claim 8, wherein, The energy storage density of the antiferroelectric capacitor is 23.13 - 67.34 J / cm 3 , and the efficiency of the antiferroelectric capacitor is 0.39 - 1.

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