A stable ferroelectric hafnium oxide-based thin film material with a wide thickness range and its preparation method

Abstract

This invention discloses a stable ferroelectric hafnium oxide-based thin film material with a wide thickness range and its preparation method, belonging to the field of materials technology. The preparation method includes: S1: preparing Hf 1‑m‑n La m Y n O2 ceramic sputtering material and La 1‑x Sr x The preparation method for MnO3 ceramic targets is as follows: mixing the raw material powders of the target, pre-firing, pressing into sheets, and sintering to obtain the ceramic target; S2: using pulsed laser deposition method, by bombarding La 1‑x Sr x MnO3 ceramic target, La grown on STO substrate 1‑x Sr x MnO3 bottom electrode layer; then bombarded with Hf 1‑m‑ n La m Y n O2 ceramic target material, in the La 1‑x Sr x Hf deposited on the MnO3 bottom electrode layer 1‑m‑n La m Y n O2 thin film is obtained to obtain the ferroelectric hafnium oxide-based thin film material. This invention can completely suppress the nonpolar monoclinic phase and has excellent thickness scalability.

Description

Technical Field

[0001] This invention belongs to the field of materials technology and relates to a ferroelectric material, particularly to a stable ferroelectric hafnium oxide-based thin film material with a wide thickness range and its preparation method. Background Technology

[0002] Ferroelectric materials, due to their reversible spontaneous polarization, have broad application prospects in fields such as non-volatile RAM (FeRAM), neuromorphic computing devices, energy storage capacitors, and piezoelectric actuators. In practical applications, different devices have significantly different requirements for the thickness of ferroelectric thin films: low-power nanoelectronic devices typically require extremely thin films (<20 nm) to achieve low-voltage actuation; while high-voltage capacitors and piezoelectric actuators often require thicknesses exceeding 50 nm or even reaching the micrometer scale to ensure sufficient voltage withstand capability or mechanical output.

[0003] Traditional perovskite ferroelectric materials (such as BaTiO3 and Pb(Zr,Ti)O3) exhibit high polarization intensity, but they suffer from poor compatibility with CMOS processes and severe size effects—when the film thickness decreases to below 20 nm, the depolarization field rapidly suppresses their ferroelectric polarization. In contrast, fluorite-structured hafnium dioxide (HfO2) and its doped derivatives exhibit robust ferroelectricity at the nanoscale (<20 nm) and possess excellent silicon process compatibility, making them a current research hotspot in the microelectronics field. However, HfO2-based ferroelectric materials face significant technical challenges in thickness extension. The ferroelectricity of HfO2 originates from the polar orthorhombic phase (… o -phase), this phase is related to the tetragonal phase ( t The monoclinic phase exhibits a close structural relationship. However, thermodynamically, the nonpolar monoclinic phase ( m -phase) is the intrinsic ground state of HfO2. As the film thickness increases (typically exceeding 30 nm), the stabilizing effect of surface energy on the polar phase weakens, while the nonpolar phase... m -phase gradually becomes dominant, leading to significant decay of ferroelectric polarization.

[0004] To stabilize the polar phase of HfO2 o In the -phase stage, various methods have been explored in existing technologies, including strain engineering, ion bombardment, single-element doping, and crystal orientation manipulation. While these methods reduce the crystal structure to some extent by adjusting lattice strain or introducing oxygen vacancies... o -phase and m The energy difference between the -phases, however, still fails to fundamentally reverse the thermodynamic energy hierarchy (i.e., m -phase is always the intrinsic ground state, and cannot completely suppress the nonpolar phase in thick films. mThe precipitation of the nonpolar monoclinic phase is a critical issue that urgently needs to be addressed in this field. Therefore, developing an intrinsically ferroelectric phase-dominated HfO2 thin film that can completely suppress the nonpolar monoclinic phase and possess high polarization intensity over a wide thickness range (from nanometer to micrometer). Summary of the Invention

[0005] This invention provides a stable ferroelectric hafnium oxide-based thin film material with a wide thickness range and its preparation method, thereby overcoming the shortcomings of the prior art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing stable ferroelectric hafnium oxide-based thin film materials with a wide thickness range, comprising the following steps: S1: preparing Hf 1-m-n La m Y n O2 ceramic sputtering material and La 1-x Sr x MnO3 ceramic target; the Hf 1-m- n La m Y n O2 ceramic sputtering material and La 1-x Sr x The preparation methods for MnO3 ceramic targets are as follows: mixing the raw material powders of the target, pre-firing, pressing into sheets, and sintering to obtain the ceramic target; the Hf 1-m-n La m Y n The raw materials for the O2 ceramic target are HfO2, La2O3, and Y2O3; the La 1-x Sr x The raw materials for the MnO3 ceramic target are La2O3, SrO, and MnCO3; S2: using pulsed laser deposition, by bombarding La... 1-x Sr x MnO3 ceramic target material, La grown on STO substrate 1-x Sr x MnO3 bottom electrode layer; then bombarded with Hf 1-m-n La m Y n O2 ceramic target material, in the La 1-x Sr x Hf deposited on the MnO3 bottom electrode layer 1-m-n La m Y n O2 thin film, to obtain the ferroelectric hafnium oxide-based thin film material.

[0007] To optimize the above technical solution, the specific measures also include: Furthermore, the Hf 1-m-nLa m Y n O2 ceramic sputtering material and La 1-x Sr x The preparation method of MnO3 ceramic target material includes the following steps: S11: Mix each raw material powder with anhydrous ethanol, and successively perform ball milling, drying and sieving to obtain a uniformly mixed raw material powder; pre-calcine the raw material powder to obtain target powder; S12: successively perform ball milling, drying and sieving of the target powder, then mix with binder, perform tableting, and isostatic pressing to obtain target blank; S13: sinter the target blank to obtain the ceramic target material.

[0008] Further, in S11, the ball milling time is 10-15 h, preferably 12 h; the pre-firing process is as follows: the temperature is increased from room temperature to 1200-1300 ℃ at a heating rate of 4-6 ℃ / min, held for 11-13 h, and then the temperature is reduced to room temperature at a cooling rate of 4-6 ℃ / min, preferably from room temperature to 1250 ℃ at a heating rate of 5 ℃ / min, held for 12 h, and then the temperature is reduced to room temperature at a cooling rate of 5 ℃ / min.

[0009] Further, in step S12, the adhesive is a PVA adhesive; the amount of the PVA adhesive is 4-6% of the mass of the target powder, preferably 5%; the pressure for the tableting process is 15-17 MPa; and the molding process takes 20-40 min, preferably 30 min.

[0010] Further, in step S13, the sintering process is as follows: the temperature is increased from room temperature to 450-550°C at a rate of 4-6°C / min, held for 0.5-1.5 h for desizing, then increased to 1300-1350°C at a rate of 4-6°C / min and held for 11-13 h for sintering, and then cooled to room temperature at a rate of 4-6°C / min. Preferably, the temperature is increased from room temperature to 500°C at a rate of 5°C / min, held for 1 h for desizing, then increased to 1300°C at a rate of 5°C / min and held for 12 h for sintering, and then cooled to room temperature at a rate of 5°C / min. The sintering temperature reaching 1300°C ensures sufficient density of the target material, which is beneficial for subsequent thin film preparation.

[0011] Furthermore, the Hf 1-m-n La m Y n In the O2 ceramic target material, m is 0.025~0.035, preferably 0.03, and n is 0.025~0.08, preferably 0.05.

[0012] Furthermore, the La 1-x Sr x In the MnO3 ceramic target, x is 0.25~0.35, preferably 0.3.

[0013] Furthermore, the La 1-x Sr x The thickness of the MnO3 bottom electrode layer is 20~30 nm, preferably 25 nm; the Hf 1-m- n La m Y n The thickness of the O2 thin film is 10~300 nm.

[0014] Further, S2 includes the following steps: S21: heating the pulsed laser deposition chamber to 750~800 °C, preferably 780 °C, and setting the oxygen partial pressure to 0.12~0.14 mbar, preferably 0.13 mbar; bombarding the La with a KrF laser of λ=248 nm. 1-x Sr x MnO3 ceramic target, La grown on the STO substrate 1-x Sr x MnO3 bottom electrode layer, with an energy density of 1~2 J•cm -2 1.5 J•cm is preferred. -2 The repetition frequency is 1.5~2.5 Hz, preferably 2 Hz; S22: The pulsed laser deposition chamber is further heated to 880~920 ℃ at a heating rate of 55~65 ℃ / min, preferably to 900 ℃, and the oxygen partial pressure is adjusted to 0.09~0.11 mbar, preferably 0.1 mbar; the Hf is bombarded. 1-m-n La m Y n O2 ceramic target material, in the La 1-x Sr x Hf is deposited on the MnO3 bottom electrode layer. 1-m-n La m Y n O2 thin film, with the same energy density and repetition frequency as S21; S23: cool to room temperature at a cooling rate of 8~12 ℃ / min, preferably 10 ℃ / min.

[0015] Secondly, the present invention also provides a stable ferroelectric hafnium oxide thin film material with a wide thickness range prepared by the above-described preparation method.

[0016] The beneficial effects of this invention are as follows: I. Highly efficient nonpolar monoclinic phase ( m-phaseComplete suppression: This invention achieves complete suppression by optimizing the doping ratio (e.g., Hf). 0.92 La 0.03 Y 0.05 O2) completely eliminates the nonpolar phase in the thick film. m-phase This makes the polar orthogonal phases o-phase It becomes the thermodynamic ground state, which is unprecedented in previous HfO2-based ferroelectric materials.

[0017] II. Excellent Thickness Scalability: Unlike single-doped films where polarization decays rapidly after thickness exceeds 20 nm, this invention maintains robust ferroelectricity in the range of 11 nm to 300 nm. In particular, in the thickness range of 135 nm to 300 nm, the polarization intensity fluctuation is less than 1%, achieving thickness-independent ferroelectric characteristics. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the preparation process of the stable ferroelectric hafnium oxide thin film material with a wide thickness range according to the present invention. Figure 2 These are ferroelectric thin films with a thickness of 11 nm in the various embodiments and comparative examples. θ -2 θ Scan results (A) and PUND hysteresis curve (B); Figure 3 Comparative Examples 1 and 2 are ferroelectric thin films of various thicknesses. θ -2 θ Scan results (A and B) and PUND hysteresis curves (C and D); Figure 4 These are HAADF-STEM cross-sectional images of the ferroelectric thin films in Comparative Examples 1 and 2. Figure 5 These are ferroelectric thin films of various thicknesses from Example 1. θ -2 θ Scan results (A) and PUND hysteresis curve (B); Figure 6 These are ferroelectric thin films of various thicknesses from Example 2. θ -2 θ Scan results (A) and PUND hysteresis curve (B); Figure 7 These are ferroelectric thin films of various thicknesses as described in Example 3. θ -2 θ Scanning results (A), PUND hysteresis curve (B), and a comparison of thickness-related ferroelectric properties with existing ferroelectric thin films (C). Figure 8 These are ferroelectric thin films of various thicknesses from Example 4. θ -2 θ Scan results (A) and PUND hysteresis curve (B); Figure 9 These are ferroelectric thin films of various thicknesses from Example 5. θ -2 θ Scan results (A) and PUND hysteresis curve (B). Detailed Implementation

[0019] The present invention will be further described below with reference to specific embodiments.

[0020] Example 1 This embodiment provides a stable ferroelectric hafnium oxide-based thin film material with a wide thickness range, and its preparation method is as follows: Figure 1 As shown, it includes the following steps: S1: Prepare Hf separately 0.945 La 0.03 Y 0.025 O2 ceramic sputtering material and La 0.7 Sr 0.3 MnO3 ceramic target.

[0021] Hf 0.945 La 0.03 Y 0.025 The preparation method of O2 ceramic target material includes the following steps: S11: 14.4096 g HfO2, 0.3540 g La2O3, and 0.2045 g Y2O3 were mixed with anhydrous ethanol and ball-milled for 12 h, dried, and sieved to obtain a uniformly mixed raw material powder. The raw material powder was then pre-calcined. The pre-calcination process was as follows: the temperature was increased from room temperature to 1250 ℃ at a rate of 5 ℃ / min, held at 1250 ℃ for 12 h, and then decreased to room temperature at a rate of 5 ℃ / min to obtain HfO2. 0.945 La 0.03 Y 0.025 O2 target powder.

[0022] S12: Hf 0.945 La 0.03 Y 0.025 The O2 target powder was ball-milled, dried, and sieved again. Hf was then... 0.945 La 0.03 Y 0.025 O2 target powder is mixed with 5% PVA binder and compressed into tablets under a pressure of 15-17 MPa. The tablets are then subjected to isostatic pressing for 30 min to obtain Hf. 0.945 La 0.03 Y 0.025 O2 target preform.

[0023] S13: Hf 0.945 La 0.03 Y 0.025The O2 target preform was sintered using the following process: the temperature was increased from room temperature to 500℃ at a rate of 5℃ / min, held at 500℃ for 1 h for desizing, then increased to 1300℃ at a rate of 5℃ / min and held for 12 h for sintering, and finally cooled to room temperature at a rate of 5℃ / min to obtain Hf. 0.945 La 0.03 Y 0.025 O2 ceramic target material.

[0024] La 0.7 Sr 0.3 Preparation methods of MnO3 ceramic targets and Hf 0.945 La 0.03 Y 0.025 The preparation methods for O2 ceramic targets are exactly the same, the only difference being that the raw materials are La2O3, SrO and MnCO3 respectively.

[0025] S2: La is bombarded sequentially using pulsed laser deposition (PLD) and a KrF laser (λ=248nm). 0.7 Sr 0.3 MnO3 ceramic target and Hf 0.945 La 0.03 Y 0.025 O2 ceramic target material is ablated and vaporized according to stoichiometric ratio, forming a high-temperature, high-pressure plasma plume within a vacuum chamber. This plume diffuses onto the (001)STO substrate, depositing and growing a high-quality epitaxial thin film. During the deposition process, La is first grown. 0.7 Sr 0.3 The MnO3 bottom electrode used 1.5 J•cm -2 The energy density and repetition frequency were set at 2 Hz, the substrate temperature was set at 780 ℃, and the oxygen partial pressure was fixed at 0.13 mbar. After the bottom electrode was deposited, the sample was not removed, and then the temperature was increased to 900 ℃ at a rate of 60 ℃ / min, the oxygen partial pressure was adjusted to 0.1 mbar, and 1.5 J•cm⁻¹ was still used. 2 Hf was deposited with an energy density and a repetition frequency of 2 Hz to a thickness of 11 nm. 0.945 La 0.03 Y 0.025 O2 film. After deposition, the film was cooled to room temperature at a cooling rate of 10 °C / min under an oxygen partial pressure of 0.1 mbar.

[0026] In this embodiment, Hf atoms with thicknesses of 40 nm, 70 nm, 90 nm, 110 nm, 135 nm, 220 nm, and 300 nm were also prepared using the above method. 0.945 La 0.03 Y 0.025O2 thin film.

[0027] Example 2 This embodiment provides a stable ferroelectric hafnium oxide-based thin film material with a wide thickness range, and its preparation method is as follows: Figure 1 As shown, it includes the following steps: S1: Prepare Hf separately 0.935 La 0.03 Y 0.035 O2 ceramic sputtering material and La 0.7 Sr 0.3 MnO3 ceramic target.

[0028] Hf 0.935 La 0.03 Y 0.035 The preparation method of O2 ceramic target material includes the following steps: S11: 14.3191 g HfO2, 0.3556 g La2O3, and 0.2875 g Y2O3 were mixed with anhydrous ethanol and sequentially ball-milled for 12 h, dried, and sieved to obtain a uniformly mixed raw material powder. The raw material powder was then pre-calcined. The pre-calcination process was as follows: the temperature was increased from room temperature to 1250 ℃ at a rate of 5 ℃ / min, held at 1250 ℃ for 12 h, and then decreased to room temperature at a rate of 5 ℃ / min to obtain HfO2. 0.935 La 0.03 Y 0.035 O2 target powder.

[0029] S12: Hf 0.935 La 0.03 Y 0.035 The O2 target powder was ball-milled, dried, and sieved again. Hf was then... 0.935 La 0.03 Y 0.035 O2 target powder is mixed with 5% PVA binder and compressed into tablets under a pressure of 15-17 MPa. The tablets are then subjected to isostatic pressing for 30 min to obtain Hf. 0.935 La 0.03 Y 0.035 O2 target preform.

[0030] S13: Hf 0.935 La 0.03 Y 0.035 The O2 target preform was sintered using the following process: the temperature was increased from room temperature to 500℃ at a rate of 5℃ / min, held at 500℃ for 1 h for desizing, then increased to 1300℃ at a rate of 5℃ / min and held for 12 h for sintering, and finally cooled to room temperature at a rate of 5℃ / min to obtain Hf. 0.935 La0.03 Y 0.035 O2 ceramic target material.

[0031] La 0.7 Sr 0.3 The preparation method of MnO3 ceramic target is the same as in Example 1.

[0032] S2: La is bombarded sequentially using pulsed laser deposition (PLD) and a KrF laser (λ=248nm). 0.7 Sr 0.3 MnO3 ceramic target and Hf 0.935 La 0.03 Y 0.035 O2 ceramic target material is ablated and vaporized according to stoichiometric ratio, forming a high-temperature, high-pressure plasma plume within a vacuum chamber. This plume diffuses onto the (001)STO substrate, depositing and growing a high-quality epitaxial thin film. During the deposition process, La is first grown. 0.7 Sr 0.3 The MnO3 bottom electrode used 1.5 J•cm -2 The energy density and repetition frequency were set at 2 Hz, the substrate temperature was set at 780 ℃, and the oxygen partial pressure was fixed at 0.13 mbar. After the bottom electrode was deposited, the sample was not removed, and then the temperature was increased to 900 ℃ at a rate of 60 ℃ / min, the oxygen partial pressure was adjusted to 0.1 mbar, and 1.5 J•cm⁻¹ was still used. 2 Hf was deposited with an energy density and a repetition frequency of 2 Hz to a thickness of 11 nm. 0.935 La 0.03 Y 0.035 O2 film. After deposition, the film was cooled to room temperature at a cooling rate of 10 °C / min under an oxygen partial pressure of 0.1 mbar.

[0033] In this embodiment, Hf atoms with thicknesses of 40 nm, 70 nm, 90 nm, 110 nm, 135 nm, 220 nm, and 300 nm were also prepared using the above method. 0.935 La 0.03 Y 0.035 O2 thin film.

[0034] Example 3 This embodiment provides a stable ferroelectric hafnium oxide-based thin film material with a wide thickness range, and its preparation method is as follows: Figure 1 As shown, it includes the following steps: S1: Prepare Hf separately 0.92 La 0.03 Y 0.05 O2 ceramic sputtering material and La 0.7 Sr 0.3 MnO3 ceramic target.

[0035] Hf 0.92 La 0.03 Y 0.05 The preparation method of O2 ceramic target material includes the following steps: S11: 14.1818 g HfO2, 0.3579 g La2O3, and 0.4134 g Y2O3 were mixed with anhydrous ethanol and sequentially ball-milled for 12 h, dried, and sieved to obtain a uniformly mixed raw material powder. The raw material powder was then pre-calcined. The pre-calcination process was as follows: the temperature was increased from room temperature to 1250 ℃ at a rate of 5 ℃ / min, held at 1250 ℃ for 12 h, and then decreased to room temperature at a rate of 5 ℃ / min to obtain HfO2. 0.92 La 0.03 Y 0.05 O2 target powder.

[0036] S12: Hf 0.92 La 0.03 Y 0.05 The O2 target powder was ball-milled, dried, and sieved again. Hf was then... 0.92 La 0.03 Y 0.05 O2 target powder is mixed with 5% PVA binder and compressed into tablets under a pressure of 15-17 MPa. The tablets are then subjected to isostatic pressing for 30 min to obtain Hf. 0.92 La 0.03 Y 0.05 O2 target preform.

[0037] S13: Hf 0.92 La 0.03 Y 0.05 The O2 target preform was sintered using the following process: the temperature was increased from room temperature to 500℃ at a rate of 5℃ / min, held at 500℃ for 1 h for desizing, then increased to 1300℃ at a rate of 5℃ / min and held for 12 h for sintering, and finally cooled to room temperature at a rate of 5℃ / min to obtain Hf. 0.92 La 0.03 Y 0.05 O2 ceramic target material.

[0038] La 0.7 Sr 0.3 The preparation method of MnO3 ceramic target is the same as in Example 1.

[0039] S2: La is bombarded sequentially using pulsed laser deposition (PLD) and a KrF laser (λ=248nm). 0.7 Sr 0.3 MnO3 ceramic target and Hf0.92 La 0.03 Y 0.05 O2 ceramic target material is ablated and vaporized according to stoichiometric ratio, forming a high-temperature, high-pressure plasma plume within a vacuum chamber. This plume diffuses onto the (001)STO substrate, depositing and growing a high-quality epitaxial thin film. During the deposition process, La is first grown. 0.7 Sr 0.3 The MnO3 bottom electrode used 1.5 J•cm -2 The energy density and repetition frequency were set at 2 Hz, the substrate temperature was set at 780 ℃, and the oxygen partial pressure was fixed at 0.13 mbar. After the bottom electrode was deposited, the sample was not removed, and then the temperature was increased to 900 ℃ at a rate of 60 ℃ / min, the oxygen partial pressure was adjusted to 0.1 mbar, and 1.5 J•cm⁻¹ was still used. 2 Hf was deposited with an energy density and a repetition frequency of 2 Hz to a thickness of 11 nm. 0.92 La 0.03 Y 0.05 O2 film. After deposition, the film was cooled to room temperature at a cooling rate of 10 °C / min under an oxygen partial pressure of 0.1 mbar.

[0040] In this embodiment, Hf atoms with thicknesses of 40 nm, 90 nm, 135 nm, and 300 nm were also prepared using the above method. 0.92 La 0.03 Y 0.05 O2 thin film.

[0041] Example 4 This embodiment provides a stable ferroelectric hafnium oxide-based thin film material with a wide thickness range, and its preparation method is as follows: Figure 1 As shown, it includes the following steps: S1: Prepare Hf separately 0.905 La 0.03 Y 0.065 O2 ceramic sputtering material and La 0.7 Sr 0.3 MnO3 ceramic target.

[0042] Hf 0.905 La 0.03 Y 0.065 The preparation method of O2 ceramic target material includes the following steps: S11: 14.0427 g HfO2, 0.3603 g La2O3, and 0.5410 g Y2O3 were mixed with anhydrous ethanol and ball-milled for 12 h, dried, and sieved to obtain a uniformly mixed raw material powder. The raw material powder was then pre-calcined. The pre-calcination process was as follows: the temperature was increased from room temperature to 1250 ℃ at a rate of 5 ℃ / min, held at 1250 ℃ for 12 h, and then decreased to room temperature at a rate of 5 ℃ / min to obtain HfO2. 0.905 La 0.03 Y 0.065 O2 target powder.

[0043] S12: Hf 0.905 La 0.03 Y 0.065 The O2 target powder was ball-milled, dried, and sieved again. Hf was then... 0.905 La 0.03 Y 0.065 O2 target powder is mixed with 5% PVA binder and compressed into tablets under a pressure of 15-17 MPa. The tablets are then subjected to isostatic pressing for 30 min to obtain Hf. 0.905 La 0.03 Y 0.065 O2 target preform.

[0044] S13: Hf 0.905 La 0.03 Y 0.065 The O2 target preform was sintered using the following process: the temperature was increased from room temperature to 500℃ at a rate of 5℃ / min, held at 500℃ for 1 h for desizing, then increased to 1300℃ at a rate of 5℃ / min and held for 12 h for sintering, and finally cooled to room temperature at a rate of 5℃ / min to obtain Hf. 0.905 La 0.03 Y 0.065 O2 ceramic target material.

[0045] La 0.7 Sr 0.3 The preparation method of MnO3 ceramic target is the same as in Example 1.

[0046] S2: La is bombarded sequentially using pulsed laser deposition (PLD) and a KrF laser (λ=248nm). 0.7 Sr 0.3 MnO3 ceramic target and Hf 0.905 La 0.03 Y 0.065O2 ceramic target material is ablated and vaporized according to stoichiometric ratio, forming a high-temperature, high-pressure plasma plume within a vacuum chamber. This plume diffuses onto the (001)STO substrate, depositing and growing a high-quality epitaxial thin film. During the deposition process, La is first grown. 0.7 Sr 0.3 The MnO3 bottom electrode used 1.5 J•cm -2 The energy density and repetition frequency were set at 2 Hz, the substrate temperature was set at 780 ℃, and the oxygen partial pressure was fixed at 0.13 mbar. After the bottom electrode was deposited, the sample was not removed, and then the temperature was increased to 900 ℃ at a rate of 60 ℃ / min, the oxygen partial pressure was adjusted to 0.1 mbar, and 1.5 J•cm⁻¹ was still used. 2 Hf was deposited with an energy density and a repetition frequency of 2 Hz to a thickness of 11 nm. 0.905 La 0.03 Y 0.065 O2 film. After deposition, the film was cooled to room temperature at a cooling rate of 10 °C / min under an oxygen partial pressure of 0.1 mbar.

[0047] In this embodiment, Hf atoms with thicknesses of 40 nm, 70 nm, 90 nm, 110 nm, 135 nm, 220 nm, and 300 nm were also prepared using the above method. 0.905 La 0.03 Y 0.065 O2 thin film.

[0048] Example 5 This embodiment provides a stable ferroelectric hafnium oxide-based thin film material with a wide thickness range, and its preparation method is as follows: Figure 1 As shown, it includes the following steps: S1: Prepare Hf separately 0.89 La 0.03 Y 0.08 O2 ceramic sputtering material and La 0.7 Sr 0.3 MnO3 ceramic target.

[0049] Hf 0.89 La 0.03 Y 0.08 The preparation method of O2 ceramic target material includes the following steps: S11: 13.9017 g HfO2, 0.3627 g La2O3, and 0.6703 g Y2O3 were mixed with anhydrous ethanol and ball-milled for 12 h, dried, and sieved to obtain a uniformly mixed raw material powder. The raw material powder was then pre-calcined. The pre-calcination process was as follows: the temperature was increased from room temperature to 1250 °C at a rate of 5 °C / min, held at 1250 °C for 12 h, and then decreased to room temperature at a rate of 5 °C / min to obtain HfO2. 0.89 La 0.03 Y 0.08 O2 target powder.

[0050] S12: Hf 0.89 La 0.03 Y 0.08 The O2 target powder was ball-milled, dried, and sieved again. Hf was then... 0.89 La 0.03 Y 0.08 O2 target powder is mixed with 5% PVA binder and compressed into tablets under a pressure of 15-17 MPa. The tablets are then subjected to isostatic pressing for 30 min to obtain Hf. 0.89 La 0.03 Y 0.08 O2 target preform.

[0051] S13: Hf 0.89 La 0.03 Y 0.08 The O2 target preform was sintered using the following process: the temperature was increased from room temperature to 500℃ at a rate of 5℃ / min, held at 500℃ for 1 h for desizing, then increased to 1300℃ at a rate of 5℃ / min and held for 12 h for sintering, and finally cooled to room temperature at a rate of 5℃ / min to obtain Hf. 0.89 La 0.03 Y 0.08 O2 ceramic target material.

[0052] La 0.7 Sr 0.3 The preparation method of MnO3 ceramic target is the same as in Example 1.

[0053] S2: La is bombarded sequentially using pulsed laser deposition (PLD) and a KrF laser (λ=248nm). 0.7 Sr 0.3 MnO3 ceramic target and Hf 0.89 La 0.03 Y 0.08O2 ceramic target material is ablated and vaporized according to stoichiometric ratio, forming a high-temperature, high-pressure plasma plume within a vacuum chamber. This plume diffuses onto the (001)STO substrate, depositing and growing a high-quality epitaxial thin film. During the deposition process, La is first grown. 0.7 Sr 0.3 The MnO3 bottom electrode used 1.5 J•cm -2 The energy density and repetition frequency were set at 2 Hz, the substrate temperature was set at 780 ℃, and the oxygen partial pressure was fixed at 0.13 mbar. After the bottom electrode was deposited, the sample was not removed, and then the temperature was increased to 900 ℃ at a rate of 60 ℃ / min, the oxygen partial pressure was adjusted to 0.1 mbar, and 1.5 J•cm⁻¹ was still used. 2 Hf was deposited with an energy density and a repetition frequency of 2 Hz to a thickness of 11 nm. 0.89 La 0.03 Y 0.08 O2 film. After deposition, the film was cooled to room temperature at a cooling rate of 10 °C / min under an oxygen partial pressure of 0.1 mbar.

[0054] In this embodiment, Hf atoms with thicknesses of 40 nm, 70 nm, 90 nm, 110 nm, 135 nm, 220 nm, and 300 nm were also prepared using the above method. 0.89 La 0.03 Y 0.08 O2 thin film.

[0055] Comparative Example 1 This comparative example provides a ferroelectric hafnium oxide-based thin film material, the preparation method of which includes the following steps: S1: Prepare Hf separately 0.97 La 0.03 O2 ceramic sputtering material and La 0.7 Sr 0.3 MnO3 ceramic target.

[0056] Hf 0.97 La 0.03 The preparation method of O2 ceramic target material includes the following steps: S11: 14.6325 g HfO2 and 0.3503 g La2O3 were mixed with anhydrous ethanol, and then ball-milled for 12 h, dried, and sieved to obtain a uniformly mixed raw material powder. The raw material powder was then pre-calcined. The pre-calcination process was as follows: the temperature was increased from room temperature to 1250 ℃ at a rate of 5 ℃ / min, held at 1250 ℃ for 12 h, and then decreased to room temperature at a rate of 5 ℃ / min to obtain HfO2. 0.97 La 0.03 O2 target powder.

[0057] S12: Hf 0.97 La 0.03 The O2 target powder was ball-milled, dried, and sieved again. Hf was then... 0.97 La 0.03 O2 target powder is mixed with 5% PVA binder and compressed into tablets under a pressure of 15-17 MPa. The tablets are then subjected to isostatic pressing for 30 min to obtain Hf. 0.97 La 0.03 O2 target preform.

[0058] S13: Hf 0.97 La 0.03 The O2 target preform was sintered using the following process: the temperature was increased from room temperature to 500℃ at a rate of 5℃ / min, held at 500℃ for 1 h for desizing, then increased to 1300℃ at a rate of 5℃ / min and held for 12 h for sintering, and finally cooled to room temperature at a rate of 5℃ / min to obtain Hf. 0.97 La 0.03 O2 ceramic target material.

[0059] La 0.7 Sr 0.3 The preparation method of MnO3 ceramic target is the same as in Example 1.

[0060] S2: La is bombarded sequentially using pulsed laser deposition (PLD) and a KrF laser (λ=248nm). 0.7 Sr 0.3 MnO3 ceramic target and Hf 0.97 La 0.03 O2 ceramic target material is ablated and vaporized according to stoichiometric ratio, forming a high-temperature, high-pressure plasma plume within a vacuum chamber. This plume diffuses onto the (001)STO substrate, depositing and growing a high-quality epitaxial thin film. During the deposition process, La is first grown. 0.7 Sr 0.3 The MnO3 bottom electrode used 1.5 J•cm -2 The energy density and repetition frequency were set at 2 Hz, the substrate temperature was set at 780 ℃, and the oxygen partial pressure was fixed at 0.13 mbar. After the bottom electrode was deposited, the sample was not removed, and then the temperature was increased to 900 ℃ at a rate of 60 ℃ / min, the oxygen partial pressure was adjusted to 0.1 mbar, and 1.5 J•cm⁻¹ was still used. 2 Hf was deposited with an energy density and a repetition frequency of 2 Hz to a thickness of 11 nm. 0.97 La 0.03 O2 film. After deposition, the film was cooled to room temperature at a cooling rate of 10 °C / min under an oxygen partial pressure of 0.1 mbar.

[0061] In this comparative example, Hf atoms with thicknesses of 15 nm, 20 nm, 25 nm, 30 nm, 60 nm, and 90 nm were also prepared using the above method. 0.97 La 0.03 O2 thin film.

[0062] Comparative Example 2 This comparative example provides a ferroelectric hafnium oxide-based thin film material, the preparation method of which includes the following steps: S1: Prepare Hf separately 0.95 Y 0.05 O2 ceramic sputtering material and La 0.7 Sr 0.3 MnO3 ceramic target.

[0063] Hf 0.95 Y 0.05 The preparation method of O2 ceramic target material includes the following steps: S11: 14.5598 g HfO2 and 0.4111 g Y2O3 were mixed with anhydrous ethanol, and then ball-milled for 12 h, dried, and sieved to obtain a uniformly mixed raw material powder. The raw material powder was then pre-calcined. The pre-calcination process was as follows: the temperature was increased from room temperature to 1250 ℃ at a rate of 5 ℃ / min, held at 1250 ℃ for 12 h, and then decreased to room temperature at a rate of 5 ℃ / min to obtain HfO2. 0.95 Y 0.05 O2 target powder.

[0064] S12: Hf 0.95 Y 0.05 The O2 target powder was ball-milled, dried, and sieved again. Hf was then... 0.95 Y 0.05 O2 target powder is mixed with 5% PVA binder and compressed into tablets under a pressure of 15-17 MPa. The tablets are then subjected to isostatic pressing for 30 min to obtain Hf. 0.95 Y 0.05 O2 target preform.

[0065] S13: Hf 0.95 Y 0.05 The O2 target preform was sintered using the following process: the temperature was increased from room temperature to 500℃ at a rate of 5℃ / min, held at 500℃ for 1 h for desizing, then increased to 1300℃ at a rate of 5℃ / min and held for 12 h for sintering, and finally cooled to room temperature at a rate of 5℃ / min to obtain Hf. 0.95 Y 0.05 O2 ceramic target material.

[0066] La0.7 Sr 0.3 The preparation method of MnO3 ceramic target is the same as in Example 1.

[0067] S2: La is bombarded sequentially using pulsed laser deposition (PLD) and a KrF laser (λ=248nm). 0.7 Sr 0.3 MnO3 ceramic target and Hf 0.95 Y 0.05 O2 ceramic target material is ablated and vaporized according to stoichiometric ratio, forming a high-temperature, high-pressure plasma plume within a vacuum chamber. This plume diffuses onto the (001)STO substrate, depositing and growing a high-quality epitaxial thin film. During the deposition process, La is first grown. 0.7 Sr 0.3 The MnO3 bottom electrode used 1.5 J•cm -2 The energy density and repetition frequency were set at 2 Hz, the substrate temperature was set at 780 ℃, and the oxygen partial pressure was fixed at 0.13 mbar. After the bottom electrode was deposited, the sample was not removed, and then the temperature was increased to 900 ℃ at a rate of 60 ℃ / min, the oxygen partial pressure was adjusted to 0.1 mbar, and 1.5 J•cm⁻¹ was still used. 2 Hf was deposited with an energy density and a repetition frequency of 2 Hz to a thickness of 11 nm. 0.95 Y 0.05 O2 film. After deposition, the film was cooled to room temperature at a cooling rate of 10 °C / min under an oxygen partial pressure of 0.1 mbar.

[0068] In this comparative example, Hf atoms with thicknesses of 15 nm, 20 nm, 25 nm, 30 nm, 60 nm, and 90 nm were also prepared using the above method. 0.95 Y 0.05 O2 thin film.

[0069] Using Cu K on a high-resolution X-ray diffractometer (Panalytical Empyrean) α The crystallinity of the products of each example and comparative example was investigated by X-ray diffraction (XRD) using radiation (λ = 1.5406 Å). The ferroelectric hysteresis loops of the products of each example and comparative example were measured using the Precision Premier II ferroelectric testing platform from Radiant Technology, USA. Prior to measuring the ferroelectric properties, a film with an area of ​​1.96 × 10⁻⁶ was sputtered onto the film surface using magnetron sputtering. -5 cm 2 A circular platinum electrode. The test results are as follows: Figures 2-9 As shown.

[0070] Figure 2In this context, A represents all ferroelectric thin films with a thickness of 11 nm. θ -2 θ Scanning results. The image shows diffraction peaks with a (111) orientation around 30.1°, corresponding to the polar phase. o-phase No nonpolar phase was detected. m-phase and intermediate phase t-phase The diffraction peaks. The lattice spacing d of the out-of-plane (111) diffraction peaks. 111 The measured value was 2.98 Å. These results indicate that all thin films are monolithic. o-phase . Figure 2 The polarization intensity and electric field of all ferroelectric thin films with a thickness of 11 nm (B) were obtained by PUND testing. PE The hysteresis curve, also known as the PUND hysteresis curve, is used to obtain the true remanent polarization intensity of the thin film. P rem As can be seen from the figure, all films at 4.0 MV cm⁻¹ -1 They all exhibit typical hysteresis loops under an electric field. P rem 10~21 μC cm -2 This indicates that the thin film prepared by the present invention has excellent ferroelectric properties.

[0071] Figure 3 , Figures 5-9 For the ferroelectric thin films of different thicknesses in the various embodiments and comparative examples θ -2 θ Scan results and PUND hysteresis curve. From Figure 3 As can be seen from A and B in the comparison, when the thickness exceeds approximately 20 nm, the nonpolar phase in the two single-doped films... m-phase The diffraction peaks gradually appeared and intensified, which led to P rem The value dropped sharply, such as Figure 3 As shown in C and D, this indicates a rapid loss of ferroelectric stability. Meanwhile, as... Figure 2 As shown, in an 11 nm thick Hf 0.97 La 0.03 O2, Hf 0.95 Y 0.05 Although no nonpolar phase was observed in the O2 thin film. m-phase The diffraction peaks appear, but this is actually due to the limited detection sensitivity of XRD for ultrathin films. Furthermore, Figure 4 High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images clearly reveal the presence of Hf 0.97 La 0.03 O2, Hf 0.95 Y 0.05O2-doped thin films contain m-phase Region. For La-Y co-doped films, from Figure 5 As can be seen from A, Hf 0.945 La 0.03 Y 0.025 For co-doped thin films with low Y-doping concentrations, as the film thickness increases, m- phase The ferroelectric properties persist and have not been suppressed, leading to a sharp decline in ferroelectric performance when the film thickness is 70 nm. Figure 5 As shown in B in the diagram. From Figures 6-9 As can be seen from A in the figure, as the Y doping concentration increases to 3.5%~8%, the HfO2 thin film material... m- phase Complete suppression was achieved, and even at a film thickness of 300 nm, the film still exhibited strong polarization intensity, such as... Figures 6-9 As shown in B in the diagram.

[0072] Among them, for Hf 0.92 La 0.03 Y 0.05 O2 co-doped ferroelectric thin films, from Figure 7 As can be seen from A in the figure, with the increase of film thickness, o-phase and t-phase The diffraction peak intensity increased accordingly, but no nonpolar phase was detected throughout the entire thickness range. m-phase Diffraction peaks indicate that Hf 0.92 La 0.03 Y 0.05 O2 co-doped ferroelectric thin films effectively suppress m-phase The formation of this structure enables stable ferroelectric properties independent of film thickness. From... Figure 7 From B and C in the diagram, we can see that Hf 0.92 La 0.03 Y 0.05 O2 co-doped ferroelectric thin films P rem The value first increases and then decreases with increasing thickness, reaching a maximum of 21.5 μC cm at 90 nm. -2 It then decreased slightly and stabilized. Notably, even with a thickness of only 300 nm, Hf... 0.92 La 0.03 Y 0.05 The O2 co-doped film still maintains a temperature of approximately 15.5 μC / cm. -2 of high P rem Values, compared to those at medium thicknesses (e.g., 135 nm) P rem The values ​​are comparable. Furthermore, Hf thicknesses in the range of 135 nm to 300 nm...0.92 La 0.03 Y 0.05 O2 co-doped thin films exhibit ultrastable polarization characteristics, i.e., Δ P rem The change is only 1%. Therefore, it can be inferred that this ultra-stable property can even be maintained within the micrometer-scale thickness range. Figure 7 As shown in C, compared with other existing ferroelectric thin films (1: Y. Yun et al., Nat. Mater. 21, 903-909 (2022). ; 2: Y. Wei et al., Nat. Mater. 17, 1095-1100 (2018). ; 3: S. Kang et al., Science 376,731-738 (2022). ; 4: C.-Y. Lin et al., Nat. Electron. 8, 560-570 (2025). ; 5: Y. Wang et al., Science 381, 558-563 (2023). ; 6: C. Zhou et al., Nat. Commun. 15,2893 (2024). ; 7: C. Zhou et al., Nat. Commun. 16, 7593 (2025). ;8:R. Alcala et al., Adv. Funct. Mater. 33, 2303261 (2023). ;9:T. Mimura, T. Shimizu, H. Uchida, O. Sakata, H. Funakubo, Appl. Phys. Lett. 113, 102901 (2018). ;10:M. Hoffmann et al., Nature 565, 464-467 (2019). The La-Y co-doped HfO2 thin films prepared in this invention achieve thickness-independent ferroelectric characteristics and excellent thickness scalability.

[0073] In this invention, unless otherwise stated, scientific and technical terms used herein have the meanings commonly understood by those skilled in the art. Furthermore, the reagents, materials, and procedures used herein are all widely used in the relevant fields.

[0074] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a stable ferroelectric hafnium oxide-based thin film material with a wide thickness range, characterized in that: Includes the following steps: S1: Prepare Hf separately 1-m-n La m Y n O2 ceramic sputtering material and La 1-x Sr x MnO3 ceramic target material; The Hf 1-m-n La m Y n O2 ceramic sputtering material and La 1-x Sr x The preparation methods for MnO3 ceramic targets are as follows: mixing the raw material powders of the target, pre-firing, pressing into sheets, and sintering to obtain the ceramic target; the Hf 1-m-n La m Y n The raw materials for the O2 ceramic target are HfO2, La2O3, and Y2O3; the La 1-x Sr x The raw materials for MnO3 ceramic targets are La2O3, SrO and MnCO3. S2: Using pulsed laser deposition method, by bombarding La 1-x Sr x MnO3 ceramic target, La grown on STO substrate 1- x Sr x MnO3 bottom electrode layer; then bombarded with Hf 1-m-n La m Y n O2 ceramic target material, in the La 1-x Sr x Hf deposited on the MnO3 bottom electrode layer 1-m-n La m Y n O2 thin film, to obtain the ferroelectric hafnium oxide-based thin film material.

2. The method for preparing a wide-thickness range stable ferroelectric hafnium oxide-based thin film material according to claim 1, characterized in that: The Hf 1-m-n La m Y n O2 ceramic sputtering material and La 1-x Sr x The preparation methods of MnO3 ceramic targets all include the following steps: S11: Mix the raw material powders with anhydrous ethanol, and then sequentially perform ball milling, drying, and sieving to obtain uniformly mixed raw material powders; pre-calcine the raw material powders to obtain target powders; S12: The target material powder is ball-milled, dried, and sieved in sequence, then mixed with a binder, compressed into tablets, and isostatically pressed to obtain a target material preform. S13: The target material blank is sintered to obtain the ceramic target material.

3. The method for preparing a wide-thickness range stable ferroelectric hafnium oxide-based thin film material according to claim 2, characterized in that: In step S11, the ball milling time is 10-15 h; The pre-firing process is as follows: the temperature is increased from room temperature to 1200-1300 ℃ at a heating rate of 4-6 ℃ / min, held for 11-13 hours, and then the temperature is reduced to room temperature at a cooling rate of 4-6 ℃ / min.

4. The method for preparing a wide-thickness range stable ferroelectric hafnium oxide-based thin film material according to claim 2, characterized in that: In step S12, the adhesive is a PVA adhesive; the amount of the PVA adhesive used is 4-6% of the mass of the target powder. The pressure for the tableting process is 15-17 MPa; the molding process takes 20-40 minutes.

5. The method for preparing a wide-thickness range stable ferroelectric hafnium oxide-based thin film material according to claim 2, characterized in that: In S13, the sintering process is as follows: the temperature is increased from room temperature to 450-550 ℃ at a heating rate of 4-6 ℃ / min, and held for 0.5-1.5 h for debinding treatment; then the temperature is increased to 1300-1350 ℃ at a heating rate of 4-6 ℃ / min and held for 11-13 h for sintering; and then the temperature is reduced to room temperature at a cooling rate of 4-6 ℃ / min.

6. The method for preparing a wide-thickness range stable ferroelectric hafnium oxide-based thin film material according to claim 1, characterized in that: The Hf 1-m-n La m Y n In O2 ceramic targets, m is 0.025~0.035 and n is 0.025~0.

08.

7. The method for preparing a wide-thickness range stable ferroelectric hafnium oxide-based thin film material according to claim 1, characterized in that: The La 1-x Sr x In MnO3 ceramic targets, x is 0.25~0.

35.

8. The method for preparing a wide-thickness range stable ferroelectric hafnium oxide-based thin film material according to claim 1, characterized in that: The La 1-x Sr x The thickness of the MnO3 bottom electrode layer is 20~30 mn; The Hf 1-m-n La m Y n The thickness of the O2 thin film is 10~300 nm.

9. The method for preparing a wide-thickness range stable ferroelectric hafnium oxide-based thin film material according to claim 1, characterized in that: S2 includes the following steps: S21: Heat the pulsed laser deposition chamber to 750~800 ℃, and set the oxygen partial pressure to 0.12~0.14 mbar; bombard the La with a KrF laser. 1-x Sr x MnO3 ceramic target, La grown on the STO substrate 1-x Sr x MnO3 bottom electrode layer, with an energy density of 1~2 J•cm -2 The repetition frequency is 1.5~2.5 Hz; S22: Continue heating the pulsed laser deposition chamber to 880-920 °C at a heating rate of 55-65 °C / min, and adjust the oxygen partial pressure to 0.09-0.11 mbar; bombard the Hf 1-m-n La m Y n O2 ceramic target material, in the La 1-x Sr x Hf is deposited on the MnO3 bottom electrode layer. 1-m-n La m Y n The O2 thin film has the same energy density and repetition frequency as S21. S23: Cool to room temperature at a cooling rate of 8~12 ℃ / min.

10. A stable ferroelectric hafnium oxide thin film material with a wide thickness range prepared by the preparation method according to any one of claims 1 to 9.

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