Oxygen-poor gradient regulated anti-fatigue hafnium-based ferroelectric thin film and capacitor thereof

Abstract

The application discloses an oxygen-deficient gradient regulated anti-fatigue hafnium-based ferroelectric thin film and a capacitor thereof. The capacitor is a sandwich-like parallel plate structure, and sequentially comprises a substrate, a bottom electrode, an oxygen-deficient gradient regulated anti-fatigue hafnium-based (HZO) ferroelectric thin film and a top electrode from bottom to top. The HZO ferroelectric thin film is prepared by atomic layer deposition, and the oxygen content in the thickness direction is regulated to make the oxygen content near the electrode lower and the oxygen content in the internal layer of the film layer gradually increase, so that the HZO thin film with an oxygen-deficient gradient is formed. In the HZO ferroelectric thin film, the thickness distribution of ZrO2 is regulated to realize the oxygen-deficient gradient structure, that is, the ZrO2 in the middle part of the HZO film layer is relatively thin, and gradually thickens towards the electrode. The structure improves the anti-fatigue performance from two aspects: providing a stable oxygen environment for the metastable ferroelectric orthorhombic phase, and reducing the domain wall pinning caused by interface defects, and enhancing the polarization reversal stability. The prepared device has a remanent polarization 2P r > of 40 muC / cm 2 2, a fatigue durability of more than 10 13 times, and the process is simple, in-situ growth and strong operability.

Description

Technical Field

[0001] This invention relates to the field of ferroelectric thin films and microelectronic memory devices, and more particularly to a fatigue-resistant hafnium-based (HZO) ferroelectric thin film with oxygen-deficient gradient structure regulation and its capacitor. Background Technology

[0002] Hafnium oxide (HfO2)-based ferroelectric materials are core materials for overcoming the bottlenecks of traditional ferroelectric materials and supporting next-generation storage and in-memory computing technologies. They possess process compatibility, miniaturization, and excellent performance, making them promising for future applications. Compared to traditional ferroelectric materials such as lead zirconate titanate (PZT), their greatest advantage lies in their high compatibility with silicon-based CMOS processes, allowing direct integration into existing semiconductor production lines and significantly reducing industrialization costs and technological barriers. Furthermore, this material overcomes the "size effect" of traditional ferroelectrics, maintaining stable ferroelectricity even at ultrathin film thicknesses below 10 nm, with a remanent polarization intensity reaching 20 μC / cm. 2 It meets the needs of high-density storage and micro / nano devices. In addition, it has the characteristics of non-volatility, high-speed read and write, and ultra-low power consumption. Its read and write speed is close to that of dynamic random access memory (DRAM), and its write power consumption is only one-thousandth of that of floating gate transistors. It shows great potential in embedded storage, ferroelectric field-effect transistors (FeFET), in-memory computing and neuromorphic devices, and has become a key solution to solve the bottleneck of storage and computing efficiency in the AI ​​and IoT era.

[0003] Despite its significant advantages, fatigue failure of HfO2-based ferroelectric thin films remains a core bottleneck restricting their large-scale application. Current research focuses on the defect and phase structure evolution mechanisms. During repeated electric field polarization cycles, the remanent polarization of the film decays rapidly, and conventional HfO2... x Zr 1-x O2 (HZO) devices typically have a cycle life of only 10. 8 This is significantly lower than the 10th percentile of commercial memory. 12 Durability requirements exceeding 1000 cycles are now being addressed. Current research indicates that fatigue stems from the synergistic failure of the material's intrinsic properties and interfaces: First, the ferroelectric phase (orthorhombic Pca21) is metastable, and cyclic electric fields easily induce its transformation into a nonpolar monoclinic phase (M phase) or a tetragonal phase (T phase), directly leading to the disappearance of residual polarization. Second, oxygen vacancies migrate directionally under the drive of an electric field, accumulating at grain boundaries and electrode interfaces, forming leakage channels and generating built-in electric fields, hindering domain flipping and exacerbating leakage current, ultimately leading to domain wall pinning or breakdown fatigue. Furthermore, charge trapping and defect evolution at the electrode / thin film interface also contribute to device performance degradation. Current research is using elemental doping, superlattice design, and interface engineering to control oxygen vacancies and phase structure, which has already improved the cycle life of some devices to 1000 cycles. 12However, breakthroughs in high temperature and long-term stability are still needed. In-depth analysis of the microscopic mechanism of fatigue and development of efficient anti-fatigue strategies are key to promoting the practical application of hafnium-based ferroelectric technology. Summary of the Invention

[0004] In view of the problems in the prior art, the purpose of this invention is to provide a fatigue-resistant hafnium-based (HZO) ferroelectric thin film and its ferroelectric capacitor with oxygen-deficient gradient regulation. This invention uses atomic layer deposition (ALD) technology to prepare HZO ferroelectric thin films. By controlling the precursor element ratio during deposition, oxygen-deficient film components (such as ZrO2) are embedded into the HZO system, creating a gradient distribution along the thickness direction with higher oxygen content on both sides and lower oxygen content in the middle. This results in an HZO ferroelectric thin film with significantly improved fatigue resistance. This oxygen-deficient gradient structure can effectively alleviate the fatigue failure problem of HZO ferroelectric thin films in two ways: First, the gradient structure can provide suitable oxygen content and oxygen environment for the metastable ferroelectric orthorhombic phase, enhancing its structural stability under alternating electric fields and suppressing the transition from polar to nonpolar phases; second, this structure can reduce the domain wall pinning effect caused by interface defects, improve the reversibility and stability of ferroelectric domain polarization reversal, and thus delay polarization decay.

[0005] The specific technical solution for achieving the purpose of this invention is as follows:

[0006] A fatigue-resistant hafnium-based ferroelectric thin film with oxygen-deficient gradient regulation is disclosed. The ferroelectric thin film is a composite structure consisting of alternating stacks of multiple HZO ferroelectric layers and multiple oxygen-deficient regulation isolation layers. The HZO ferroelectric layers are hafnium-zirconium oxide solid solution films of constant thickness. The oxygen-deficient regulation isolation layers are dielectric films capable of creating an oxygen-deficient concentration gradient within the film. Along the film thickness direction, the oxygen-deficient regulation isolation layers exhibit a gradient distribution structure with greater thickness on both sides and less thickness near the center. The gradient distribution of the oxygen-deficient regulation isolation layers creates a continuous oxygen-deficient gradient environment within the film, regulating the oxygen vacancy distribution, stabilizing the ferroelectric phase of the HZO film, and improving the fatigue resistance of the ferroelectric thin film. The HZO is HfxZr1-xO. 2， x=0.5; the oxygen-deficient control isolation layer is a ZrO2 thin film with a single-layer thickness gradient ranging from 0.1 to 1 nm; the HZO ferroelectric layer is Hf 0.5 Zr 0.5 The O2 thin film was prepared by alternating deposition of HfO2 atomic layers and ZrO2 atomic layers in a 1:1 ratio, with each HZO ferroelectric layer having a uniform thickness.

[0007] Furthermore, the stacking structure of the hafnium-based ferroelectric thin film along the thickness direction is: HZO→ZrO2→HZO→ZrO2→HZO→ZrO2→HZO→ZrO2→HZO→ZrO2→HZO→ZrO2→HZO→ZrO2→HZO, wherein the thickness of the HZO ferroelectric layer ranges from 0.2 to 2 nm, the thickness of the isolation layer ZrO2 film ranges from 0.1 to 1 nm, and the total thickness of the hafnium-based ferroelectric thin film ranges from 2 to 20 nm.

[0008] A fatigue-resistant ferroelectric capacitor includes a substrate, a bottom electrode, a ferroelectric functional layer, and a top electrode; the ferroelectric functional layer is the aforementioned oxygen-depleted gradient-regulated fatigue-resistant hafnium-based ferroelectric thin film.

[0009] Furthermore, the substrate is any one of a rigid semiconductor substrate, a rigid insulating substrate, and a flexible substrate, wherein the substrate is lightly doped with Si, Si / SiO2, or flexible mica material.

[0010] Furthermore, both the bottom electrode and the top electrode are made of conductive materials and are fabricated using a patterning process.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] 1) Significantly improves the structural stability and fatigue resistance of HfO2-based ferroelectric thin films. This invention constructs a gradient HZO thin film with oxygen-rich sides and oxygen-poor center through atomic layer deposition in situ. This creates a gradual change in composition and stress distribution along the thickness direction, providing a more suitable lattice environment and oxygen vacancy distribution for the metastable ferroelectric orthorhombic phase, effectively suppressing the transition from the polar phase to the non-polar monoclinic phase under repeated polarization cycles. Simultaneously, this gradient structure weakens defect accumulation and charge pinning at the electrode / film interface, reduces domain wall flipping resistance, and ensures high stability of ferroelectric polarization under long-term electric field excitation. The fabricated device achieves fatigue durability exceeding 10... 13 This is far superior to traditional uniform HZO thin films, significantly improving the service life and reliability of ferroelectric devices.

[0013] 2) Strong process compatibility and controllability, with potential for large-scale application. This invention achieves in-situ growth of gradient structures based on mature atomic layer deposition technology. The oxygen-deficient gradient structure design can be completed simply by programmatically adjusting the precursor ingress ratio, eliminating the need for complex post-processing steps such as high-temperature annealing and ion implantation. The process steps are simple and highly operable. This method is highly compatible with existing CMOS integrated circuit fabrication processes, allowing direct in-situ film formation on standard bottom electrodes, avoiding interface contamination and structural damage. In obtaining the remaining polarized 2P... r > 40 μC / cm 2 While maintaining the excellent ferroelectric properties, it also preserves the uniformity and interface quality of the thin film, providing an efficient and feasible technical path for the industrial fabrication of high-density ferroelectric storage, in-memory computing devices and neuromorphic devices. Attached Figure Description

[0014] Figure 1 These are schematic diagrams of the ferroelectric thin film structures in the embodiments and comparative examples;

[0015] Figure 2 Comparison of GIXRD images of the ferroelectric thin films prepared in the examples and comparative examples;

[0016] Figure 3 STEM comparison images of the ferroelectric thin films prepared in the examples and comparative examples;

[0017] Figure 4 This is a comparison diagram of the fatigue performance of ferroelectric thin films in the examples and comparative examples;

[0018] Figure 5 This is a comparison graph showing the capacitance changes during the fatigue process of ferroelectric thin films in the examples and comparative examples;

[0019] Figure 6 The ultralong fatigue resistance curve of the ferroelectric thin film prepared in the example is shown. Detailed Implementation

[0020] The following detailed description of specific embodiments of the present invention, in conjunction with preferred embodiments, further illustrates the relevant details. When numerical ranges are given in the embodiments, it should be understood that, unless otherwise specified in the present invention, both endpoints of each numerical range, as well as any value between the two endpoints, may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by those skilled in the art. In addition to the specific methods, devices, and materials used in the embodiments, the present invention can be implemented using any prior art methods, devices, and materials similar to or equivalent to those described in the embodiments of the present invention, provided that those skilled in the art possess the prior art and the description of the present invention.

[0021] The present invention discloses a fatigue-resistant HZO ferroelectric thin film with oxygen-deficient gradient regulation and its capacitor. The core feature of this invention is that the oxygen content of the HZO ferroelectric thin film can be precisely controlled along its thickness, thereby forming a non-uniform oxygen content gradient distribution. Specifically, along the film thickness, the oxygen content is relatively high and the oxygen vacancy concentration is low near the upper and lower interfaces. As the film extends from the interface towards the central region, the oxygen content gradually decreases and the oxygen vacancy concentration increases accordingly, ultimately resulting in a typical gradient distribution of oxygen. The HZO ferroelectric capacitor fabricated using this structure employs a stacked structure design, consisting of, from bottom to top, a substrate, a bottom electrode, an HZO ferroelectric functional layer grown in situ using atomic layer deposition, and a top electrode layer. Its fabrication includes the following steps:

[0022] Step 1: Place one or more of the following, such as lightly doped Si, Si / SiO2, and flexible mica, including a semiconductor rigid substrate, an insulating substrate, and a flexible substrate, in acetone, isopropanol, deionized water, and anhydrous ethanol in sequence, and clean them with an ultrasonic cleaner for 15-20 minutes each, and then dry them with a nitrogen gun for later use.

[0023] Step 2: Fabricate a metal or conductive non-metal bottom electrode on the cleaned substrate using a patterned photolithography process;

[0024] Step 3: This step is the focus of this invention. An HZO ferroelectric layer is grown on the bottom electrode using atomic layer deposition (ALD) technology, with a thickness ranging from 5 nm to 30 nm. By controlling the doping elements / content, deposition atmosphere, and annealing process, a gradient distribution of oxygen content and oxygen vacancies along the thickness direction is achieved. For example, in an embodiment of this invention, ZrO2 films of different thicknesses are deposited along the thickness dimension of the HZO film, ultimately forming an oxygen-deficient gradient HZO film.

[0025] Step 4: Repeat step 2 to fabricate a metal or conductive non-metal top electrode using patterned photolithography. The bottom electrode and top electrode are metals or conductive non-metals with low thermal expansion coefficients and a thickness of 0.1 nm to 100 nm. At this point, the ferroelectric capacitor consisting of bottom electrode-ferroelectric thin film-top electrode has been fabricated.

[0026] Step 5: Rapidly anneal the ferroelectric capacitor to crystallize the ferroelectric thin film and form a ferroelectric orthorhombic phase. The prepared ferroelectric capacitor is a sandwich-structured parallel-plate capacitor, which is used for related polarization electrical characterization.

[0027] A fatigue-resistant HZO ferroelectric thin film and its capacitor prepared by the above steps.

[0028] Example

[0029] (1) Substrate treatment: SiO2 / heavily doped p-type Si substrate (SiO2 thickness of 100 nm) is placed in acetone, isopropanol, deionized water and anhydrous ethanol in sequence, and cleaned with an ultrasonic cleaner for 15-20 minutes, and then dried with a nitrogen gun for later use.

[0030] (2) Bottom electrode fabrication: A specific bottom electrode pattern is patterned by photolithography, and the bottom electrode W is grown by magnetron sputtering with a thickness of about 10~100 nm. The substrate is then placed in a stripping solution for stripping and resist removal to prepare a complete bottom electrode pattern W.

[0031] (3) Deposition of oxygen-deficient gradient HZO thin film (GZ-HZO): ① In this embodiment, atomic layer deposition (ALD) is used for film preparation. The entire process is carried out in a vacuum environment, and the vacuum degree of the cavity is controlled to be less than 10. -1Pa; the film deposition temperature is set to 120–300 °C. ② Selection of precursors used for ALD deposition: tetratetra(dimethylamino)hafnium (TDMAHf) is used as the Hf precursor, tetratetra(dimethylamino)zirconium (TDMAZr) is used as the Zr precursor, and deionized water or ozone is used as the O precursor; during film growth, the heating temperature of the Hf and Zr precursor sources is constantly controlled at 50–90 °C. ③ The oxygen-deficient gradient anti-fatigue GZ-HZO ferroelectric film described in this embodiment is composed of two types of functional films: the first type is Hf 0.5 Zr 0.5 The O2 thin film is prepared by alternating atomic layers of monolayer ZrO2 and monolayer HfO2 in a 1:1 ratio, with a fixed thickness of 1 nm for the HZO thin film. The second type is a pure ZrO2 isolation film, which serves as an interlayer isolation layer, with a single-layer thickness adjustable from 0.1 to 1 nm. ④ In this embodiment, a pure ZrO2 thin film is used as a spacer layer in the thickness direction of the HZO-based ferroelectric thin film to separate the 1 nm thick HZO thin films layer by layer. The core structural feature is that the ZrO2 isolation layer is thickest near the upper and lower electrodes along the overall thickness direction of the film, gradually thinning towards the center of the film, forming a ZrO2 oxygen-deficient gradient distribution structure that is thick on both sides and thin in the middle. ⑤ Specific layer-by-layer growth implementation method: On any suitable substrate surface, atomic layer deposition is used to grow layer by layer in a fixed order, with the following stacking sequence: 1 nm HZO → 1 nm ZrO2 → 1 nm HZO → 0.3 nm ZrO2 → 1 nm HZO → 0.2 nm ZrO2 → 1 nm HZO → 0.2 nm ZrO2 → 1 nm HZO → 0.3 nm ZrO2 → 1 nm HZO → 1 nm ZrO2 → 1 nm HZO; After the overall stacking is completed, the total thickness of the film is about 10 nm, accurately achieving a gradient arrangement where the ZrO2 isolation layer is thicker at both ends and thinner in the middle.

[0032] (4) Top electrode fabrication: A specific top electrode pattern is patterned by photolithography, and the top electrode W is grown by magnetron sputtering with a thickness of about 10~100 nm. Then the substrate is placed in the resist solution to remove the resist and a complete W top electrode pattern is prepared.

[0033] (5) Rapid annealing of ferroelectric capacitors: The prepared ferroelectric capacitors are placed in a rapid annealing furnace and annealed at 350~550℃ / 30~60 s to crystallize the GZ-HZO thin film to form a ferroelectric orthorhombic phase.

[0034] Comparative Example

[0035] (1) Substrate treatment: SiO2 / heavily doped p-type Si substrate (SiO2 thickness of 100 nm) is placed in acetone, isopropanol, deionized water and anhydrous ethanol in sequence, and cleaned with an ultrasonic cleaner for 15-20 minutes, and then dried with a nitrogen gun for later use.

[0036] (2) Bottom electrode fabrication: A specific bottom electrode pattern is patterned by photolithography, and the bottom electrode W is grown by magnetron sputtering with a thickness of about 10~100 nm. The substrate is then placed in a stripping solution for stripping and resist removal to prepare a complete bottom electrode pattern W.

[0037] (3) HZO thin film deposition: The film was prepared using the ALD process, and the entire process was carried out in a vacuum environment, with the vacuum level of the chamber controlled to be less than 10. -1 Pa; the film deposition temperature was set to 120–300 °C. Precursor selection for ALD deposition: tetratetra(dimethylamino)hafnium (TDMAHf) was used as the Hf precursor, tetratetra(dimethylamino)zirconium (TDMAZr) was used as the Zr precursor, and deionized water or ozone was used as the O precursor; during film growth, the heating temperature of the Hf and Zr precursor sources was constantly controlled at 50–90 °C. The HZO ferroelectric film described in this comparative example was grown by alternating monolayers of ZrO2 and HfO2 at a 1:1 atomic layer ratio. 0.5 Zr 0.5 O2 thin film, 10 nm thick;

[0038] (4) Top electrode fabrication: A specific bottom electrode pattern is patterned by photolithography, and a bottom electrode W is grown by magnetron sputtering with a thickness of about 10~100 nm. Then the substrate is placed in the resist solution to remove the resist and a complete bottom electrode pattern W is prepared.

[0039] (5) Rapid annealing of ferroelectric capacitors: The prepared ferroelectric capacitors are placed in a rapid annealing furnace and annealed at 350~550℃ / 30~60 s to crystallize the HZO thin film to form a ferroelectric orthorhombic phase.

[0040] The HZO-based ferroelectric thin films prepared in the above embodiments and comparative examples all adopt a typical device structure. The device is a sandwich-type parallel plate ferroelectric capacitor, which is composed of a substrate, a tungsten (W) bottom electrode, an HZO ferroelectric functional thin film, and a tungsten (W) top electrode stacked in sequence. The structure is regular and suitable for ferroelectric performance characterization and electrical testing.

[0041] Figure 1 shows schematic diagrams of the ferroelectric thin film structures corresponding to the embodiments and comparative examples. It is clear from the figure that the oxygen-deficient gradient GZ-HZO thin film prepared in the embodiments is based on the structure of the HZO thin film, with composition and thickness controlled to gradually reduce the thickness of the ZrO2 layer from thickest towards the center of the film along the direction near the top and bottom electrodes, ultimately forming a gradient structure. In contrast, the ordinary HZO thin film in the comparative example has a uniform layered structure, formed by alternating deposition of single-layer ZrO2 and single-layer HfO2 in a 1:1 ratio, with no significant gradient change in composition and thickness along the film thickness direction. The core purpose of designing the GZ-HZO ferroelectric thin film with a ZrO2 thickness gradient is to precisely control the distribution of oxygen vacancies and the stability of the ferroelectric phase within the film. By distributing the ZrO2 thickness along the film thickness direction—thicker near the top and bottom W electrodes and thinner in the center—a more suitable oxygen gradient and stress field can be formed at the interface, inhibiting oxygen vacancy migration and aggregation, and improving the film's fatigue resistance and thermal stability. Meanwhile, this gradient structure can optimize the interface band matching, reduce leakage current, and improve the uniformity of ferroelectric domain flipping and domain pinning effect.

[0042] Figure 2 The figures show a comparison of grazing incidence X-ray diffraction (GIXRD) spectra of the ferroelectric thin films prepared in the examples and comparative examples. As can be seen from the figures, both the example and comparative samples can form stable ferroelectric phase structures and effectively suppress the formation of non-ferroelectric monoclinic phases. Specifically, the characteristic diffraction peaks of the orthorhombic and tetragonal phases corresponding to an incident angle of approximately 30.5° are significantly enhanced in both groups of samples, indicating a high proportion of ferroelectric phase and good crystallinity; while the characteristic diffraction peaks of the corresponding monoclinic phase have extremely low intensities and are almost unobservable in the spectra.

[0043] Figure 3 The images show the scanning transmission electron microscopy (STEM) characterization results of the ferroelectric thin films prepared in the examples and comparative examples. The crystal orientation and microstructure characteristics of the two types of films are clearly distinguishable from the figures. Typical lattice fringes of the ferroelectric orthorhombic phase are clearly observed in both the examples and comparative examples, corresponding to the

[101] and

[110] crystal orientations, respectively. This result directly confirms that the films in both systems successfully formed highly crystalline ferroelectric orthorhombic phase structures with clear crystal orientation and regular lattice arrangement, which corroborates the aforementioned GIXRD test results and provides direct microstructural evidence for the excellent ferroelectric properties of the films.

[0044] Figure 4 The fatigue characteristic curves of the ferroelectric thin film prepared in the example and the HZO ferroelectric thin film prepared in the comparative example are shown. It can be clearly seen from the fatigue characteristic curves that the remanent polarization intensity P of the two films is different. r The changes with the number of polarization reversals show significant differences. The comparative HZO thin film, after 10... 10 After the secondary polarization reversal cycle, its P rSignificant degradation, reaching approximately 50%, indicates that long-term polarization reversal damages the ferroelectric domain structure of the thin film, leading to oxygen vacancy migration and accumulation, thereby reducing its ferroelectric performance stability and limiting its fatigue resistance. In contrast, the GZ-HZO thin film in the example, under the same 10... 10 After the secondary polarization flip cycle, P r The results remained almost unchanged with no significant attenuation, which fully demonstrates that the gradient structure can effectively suppress domain pinning and oxygen vacancy migration inside the film during fatigue, significantly improve the fatigue resistance of the film, and ensure that it can stably maintain ferroelectric properties during long-term service.

[0045] also, Figure 5 The capacitance-voltage (CV) curves further confirm this conclusion. The capacitance of the comparative HZO thin film fluctuated significantly after multiple polarization reversals, indicating a change in its internal crystal structure and the possible formation of a non-ferroelectric phase. In contrast, the capacitance of the GZ-HZO thin film in the embodiment remained stable throughout the test, without significant fluctuations, indicating that its internal orthorhombic phase structure has higher stability and is less prone to phase transitions. This is the core reason why its fatigue resistance is superior to that of the HZO thin film. In summary, gradient design effectively improves the fatigue resistance and crystal structure stability of HZO ferroelectric thin films. Figure 6 The durability test curves of the GZ-HZO ferroelectric thin film prepared in the examples are shown, intuitively demonstrating the ferroelectric performance stability of the film under extreme long-term service conditions. The test results show that the GZ-HZO thin film exhibits good ferroelectric performance stability under long-term polarization reversal cycling for more than 10... 13 After the secondary polarization flip cycle, its 2P r It can still be stably maintained at about 40 μC / cm 2 No significant degradation or fatigue failure was observed, fully demonstrating the excellent long-term durability of the film, which far exceeds the service life of conventional HZO ferroelectric films.

[0046] Based on all test results, the core advantages of this invention can be summarized as follows: ① The ferroelectric thin film exhibits outstanding durability, compared to the comparative HZO thin film at 10... 10 After the second cycle, P r Despite a 50% degradation, the GZ-HZO film in this example maintains stable performance even at higher cycle counts, which solves the problem of traditional HZO films exhibiting poor performance at high cycle counts. r The significant degradation problem is addressed by greatly extending the device's lifespan; ② Excellent and stable ferroelectric properties, including high remanent polarization (40 μC / cm²) and coercive field (E... c① It has an oxygen content of approximately 1 MV / cm and is smaller than that of the comparative HZO, while also possessing good insulation properties and crystal structure stability; ② The structure is scientifically and rationally designed. The oxygen-deficient gradient structure does not require complex preparation processes and can effectively control the distribution of oxygen vacancies and stress field, taking into account both performance and preparation feasibility. It provides a new technical path for the research and development and application of high-reliability and long-life ferroelectric devices and has important practical application value.

Claims

1. A fatigue-resistant hafnium-based ferroelectric thin film with oxygen-deficient gradient regulation, characterized in that, The ferroelectric thin film is a composite structure consisting of alternating stacks of multiple HZO ferroelectric layers and multiple oxygen-deficient control isolation layers. The HZO ferroelectric layers are hafnium-zirconium oxide solid solution films of constant thickness. The oxygen-deficient control isolation layers are dielectric films capable of creating an oxygen-deficient concentration gradient within the film. Along the film thickness direction, the oxygen-deficient control isolation layers exhibit a gradient distribution structure with greater thickness on both sides and less thickness near the center. This gradient distribution of the oxygen-deficient control isolation layers creates a continuous oxygen-deficient gradient environment within the film, regulating oxygen vacancy distribution, stabilizing the ferroelectric phase of the HZO film, and improving the fatigue resistance of the ferroelectric thin film. The HZO is HfxZr1-xO. 2， x=0.5; the oxygen-deficient control isolation layer is a ZrO2 thin film with a single-layer thickness gradient ranging from 0.1 to 1 nm; the HZO ferroelectric layer is Hf 0.5 Zr 0.5 The O2 thin film was prepared by alternating deposition of HfO2 atomic layers and ZrO2 atomic layers in a 1:1 ratio, with each HZO ferroelectric layer having a uniform thickness.

2. The oxygen-deficient gradient-regulated fatigue-resistant hafnium-based ferroelectric thin film according to claim 1, characterized in that, The stacking structure of the hafnium-based ferroelectric thin film along the thickness direction is: HZO→ZrO2→HZO→ZrO2→HZO→ZrO2→HZO→ZrO2→HZO→ZrO2→HZO→ZrO2→HZO→ZrO2→HZO, wherein the thickness of the HZO ferroelectric layer ranges from 0.2 to 2 nm, the thickness of the isolation layer ZrO2 film ranges from 0.1 to 1 nm, and the total thickness of the hafnium-based ferroelectric thin film ranges from 2 to 20 nm.

3. A fatigue-resistant ferroelectric capacitor, characterized in that, It includes a substrate, a bottom electrode, a ferroelectric functional layer, and a top electrode; the ferroelectric functional layer is the oxygen-depleted gradient-controlled fatigue-resistant hafnium-based ferroelectric thin film as described in claim 1.

4. The fatigue-resistant ferroelectric capacitor according to claim 3, characterized in that, The substrate is any one of a rigid semiconductor substrate, a rigid insulating substrate, and a flexible substrate, and the substrate is lightly doped with Si, Si / SiO2, or flexible mica material.

5. The fatigue-resistant ferroelectric capacitor according to claim 3, characterized in that, Both the bottom electrode and the top electrode are made of conductive materials and are fabricated using a patterning process.

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