A method for modulating the ferroelectric crystal phase of hafnium oxide based on a superlattice structure

Abstract

A method for modulating the ferroelectric crystal phase of hafnium-based oxides based on a superlattice structure, in which each hafnium oxide layer in the hafnium-based ferroelectric thin film is designed to be composed of m hafnium oxide sub-layers stacked, and each doping element layer is designed to be composed of n doping element sub-layers stacked; the hafnium oxide layer and the doping element layer are stacked to form a superlattice structure, and by determining the values of m and n, the ferroelectric crystal phase of hafnium-based oxides is modulated to be dominated by the o-phase, dominated by the t-phase or an o / t mixed phase. The method is as follows: by volume, when the content of the o-phase is greater than 60%, it is dominated by the o-phase, 2 ≤ m ≤ 10, n = 1.5 × m; when the content of the t-phase is greater than 60%, it is dominated by the t-phase, 20 ≤ m ≤ 30, n = 2.5 × m; when the difference between the content of the o-phase and the content of the t-phase does not exceed 20%, it is an o / t mixed phase, 10 < m < 20, n = 2 × m; where m is an even number. The present invention can achieve the modulation of the crystal phase of the hafnium-based ferroelectric thin film, extremely low leakage current and high reliability.

Description

Technical Field

[0001] The present invention belongs to the technical field of microelectronic devices, and particularly relates to a method for modulating the ferroelectric crystal phase of hafnium oxide-based films based on a superlattice structure. Background Art

[0002] With the rapid development of information technologies such as the Internet and artificial intelligence, higher requirements are put forward for the storage density, access speed, and number of operations of memories. Due to excellent ferroelectric and antiferroelectric properties, hafnium oxide-based ferroelectric films can be widely applied to various functional storage devices. In addition, the excellent CMOS process compatibility of hafnium oxide-based ferroelectric films makes them gradually become the key materials for next-generation storage devices.

[0003] The main phase structures of hafnium oxide-based ferroelectric films are monoclinic phase (m-phase), orthorhombic phase (o-phase), and tetragonal phase (t-phase). Generally, the paraelectric characteristics of hafnium oxide-based ferroelectric films are mainly in the m-phase, the ferroelectric characteristics are mainly in the o-phase, and the antiferroelectric characteristics are mainly in the t-phase. In the actual application of memories, the ferroelectric or antiferroelectric properties of the films are usually required, and the m-phase is preferably suppressed as much as possible. When the crystal phase of the film is in a mixed state of the o-phase and the t-phase, the film can generate extremely high dielectric response, which is beneficial to the high-density storage of memories. Therefore, for different application requirements, the crystal phase modulation of hafnium oxide-based ferroelectric films is an essential means.

[0004] However, currently, traditional hafnium oxide-based ferroelectric films have limitations in crystal phase modulation. On the one hand, the method of modulating the crystal phase by changing the electrode to affect the external stress will cause process compatibility problems. On the other hand, modulating the crystal phase by only changing the ratio of hafnium oxide and other ferroelectric doping elements through single-layer growth will form a solid solution inside, and the device performance will be unstable due to uneven internal crystal phase distribution. In addition, the leakage and reliability problems of hafnium oxide-based ferroelectric films also severely limit their application in low-power and high-reliability storage devices. Summary of the Invention

[0005] In order to overcome the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a method for modulating the ferroelectric crystal phase of hafnium oxide-based films based on a superlattice structure, so as to achieve crystal phase modulation, extremely low leakage, and high reliability of hafnium oxide-based ferroelectric films.

[0006] In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A method for modulating the ferroelectric crystal phase of hafnium oxide-based films based on a superlattice structure, each hafnium oxide layer in the hafnium oxide-based ferroelectric film is designed to be stacked by m hafnium oxide sub-layers, and each doping element layer is designed to be stacked by n doping element sub-layers; the hafnium oxide layer and the doping element layer are stacked to form the superlattice structure.

[0008] According to the present invention, on the one hand, the superlattice structure introduces interlayer stress between the hafnium oxide layer and the doped element layer, affecting the crystal phase; on the other hand, the concentration ratio of the doped element to hafnium is closely related to the crystal phase structure of the hafnium-based ferroelectric thin film, and its effect is mainly reflected in lattice stress, energy barrier, and interlayer interface effect. Therefore, the crystal phase modulation described in the present invention is achieved by determining the values of m and n, thereby modulating the hafnium-based ferroelectric crystal phase to be dominated by the o-phase, dominated by the t-phase, or an o / t mixed phase.

[0009] Specifically, when 2 ≤ m ≤ 10 and n = 1.5 × m, the doped element introduces lattice distortion. At this time, the proportion of the doped element is relatively small, which can make the hafnium-based ferroelectric thin film stable in the o-phase but difficult to cross the energy barrier between the o / t phases. The compressive stress between layers also promotes the stability of the o-phase, ensuring that the o-phase is dominant. When the o-phase is defined as dominant in the present invention, by volume, the content of the o-phase is greater than 60%.

[0010] When 20 ≤ m ≤ 30 and n = 2.5 × m, the relatively high proportion of the doped element and the significant weakening of the interlayer stress effect caused by the increase in the single-layer thickness enable the thin film to cross the barrier between the o / t phases and be stable in the t-phase, ensuring that the t-phase is dominant. When the t-phase is defined as dominant in the present invention, by volume, the content of the t-phase is greater than 60%.

[0011] When 10 < m < 20 and n = 2 × m, the t-phase introduced by the doped element competes with the o-phase of hafnium. The interlayer stress results in the generation of a polymorphic phase boundary, and the energy barrier between the o / t phases is significantly weakened, causing the two to mix and form an o / t mixed phase. At this time, the dielectric properties of the hafnium-based ferroelectric thin film will be significantly improved. When the o / t mixed phase is defined in the present invention, by volume, the difference between the content of the o-phase and the content of the t-phase does not exceed 20%.

[0012] Obviously, to ensure that n is an integer, in the present invention, on the premise of meeting the range requirements, m should be an even number.

[0013] Thus, the method for modulating the hafnium-based ferroelectric crystal phase based on the superlattice structure in the present invention can effectively improve the interface quality and material uniformity by adopting a periodic superlattice structure in the hafnium-based ferroelectric thin film, realize crystal phase modulation and optimize the leakage characteristics and reliable performance, and obtain a highly reliable thin film. On the one hand, since the superlattice structure truncates the conductive path, a low-leakage thin film is achieved; on the other hand, the superlattice structure introduces interlayer stress between the hafnium oxide layer and the doped element layer. By regulating the number of hafnium oxide and doped element layers and the overall thickness, different stress effects will be caused, thereby realizing crystal phase modulation.

[0014] In one embodiment, the hafnium oxide-based ferroelectric thin film is composed of k hafnium oxide layers and k doped element layers stacked together. The hafnium oxide-based ferroelectric thin film is disposed between a substrate and a top metal electrode to form a ferroelectric capacitor, where there is a hafnium oxide layer on the upper side of the substrate and a doped element layer on the lower side of the top metal electrode. When k ≥ 2, the hafnium oxide layers and the doped element layers are stacked alternately.

[0015] In one embodiment, the thickness of each doped element sub-layer is 0.08 nm - 0.12 nm, and the thickness of each hafnium oxide sub-layer is 0.08 nm - 0.12 nm. Generally, the total thickness of the hafnium oxide-based ferroelectric thin film is 10 nm - 30 nm, and it can have a small range of fluctuations according to the number of hafnium oxide sub-layers and doped element sub-layers.

[0016] In one embodiment, the top metal electrode is grown and prepared on the last stacked doped element layer by a sputtering process, and then annealed in a nitrogen atmosphere at 400 °C - 650 °C for 30 seconds - 10 minutes to complete crystallization.

[0017] In one embodiment, each of the hafnium oxide layers is prepared by atomic layer deposition, and the method is as follows:

[0018] In a vacuum environment, a hafnium source, an oxygen source, and a carrier gas are set. The hafnium source pulse time is set to 0.5 - 10 s, the purge time is 5 - 30 s, the oxygen source pulse time is 0.1 - 2.5 s, and the purge time is 8 - 40 s, and m hafnium oxide sub-layers are grown in sequence;

[0019] Each of the doped element layers is prepared by atomic layer deposition, and the method is as follows:

[0020] In a vacuum environment, a doped element source, an oxygen source, and a carrier gas are set. The doped element source pulse time is set to 1 - 8 s, the purge time is 5 - 25 s, the oxygen source pulse time is 0.1 - 2.5 s, and the purge time is 8 - 40 s, and n doped element sub-layers are grown in sequence.

[0021] In one embodiment, in the atomic layer deposition process, the chamber temperature is set to 200 °C - 350 °C.

[0022] In one embodiment, the oxygen source is water, ozone, oxygen, hydrogen peroxide, or nitrogen oxides, and oxygen can also be replaced in the form of oxygen plasma; the carrier gas is nitrogen, argon, helium, hydrogen, or a nitrogen-hydrogen mixture.

[0023] In one embodiment, the hafnium source is hafnium tetrakis(dimethylamino); the doping element source is yttrium tris(cyclopentadienylmethyl), trimethylmethoxysilane, trimethylaluminum, titanium tetraisopropoxide, lanthanum tris[bis(trimethylsilyl)amide], strontium tetramethylheptanedioate, scandium bis(trimethylsilyl)amide, cerium trifluoromethanesulfonate, or zirconium tetrakis(dimethylamino). Accordingly, the material of the doped element layer is yttrium oxide, silicon oxide, aluminum oxide, titanium oxide, lanthanum oxide, strontium oxide, scandium oxide, cerium oxide, or zirconium oxide. The hafnium-based ferroelectric thin film is denoted as HYO, HSO, HAO, HTO, HLO, HSrO, HScO, or HCeO. Among them, HYO is hafnium oxide doped with yttrium, HSO is hafnium oxide doped with silicon, HAO is hafnium oxide doped with aluminum, HTO is hafnium oxide doped with titanium, HLO is hafnium oxide doped with lanthanum, HSrO is hafnium oxide doped with strontium, HScO is hafnium oxide doped with scandium, and HCeO is hafnium oxide doped with cerium.

[0024] In one embodiment, the substrate is a semiconductor substrate or a metal substrate with a thickness greater than 15 nm. Typical semiconductor substrates include, for example, Si, Ge, SiGe, GaN, GaAs, and SiC, etc. Typical metal substrates include, for example, tungsten, titanium, copper, aluminum, platinum, iridium, ruthenium, tungsten nitride, titanium nitride, tantalum nitride, iridium oxide, ruthenium oxide, tungsten carbide, titanium carbide, tungsten silicide, titanium silicide, and tantalum silicide, etc. The present invention can be selected according to requirements.

[0025] In one embodiment, the material of the top metal electrode is tungsten, titanium, copper, aluminum, platinum, iridium, ruthenium, tungsten nitride, titanium nitride, tantalum nitride, iridium oxide, ruthenium oxide, tungsten carbide, titanium carbide, tungsten silicide, titanium silicide, or tantalum silicide. The present invention can be selected according to requirements and has a thickness greater than 15 nm.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] First: Based on the superlattice structure, by regulating the number of hafnium oxide sub-layers and doped element sub-layers, the present invention can accurately, stably, and reliably modulate the crystal phase, enabling the thin film to stably select ferroelectric or antiferroelectric properties according to different application scenarios, thus enhancing the operation flexibility and applicability of the hafnium-based ferroelectric thin film.

[0028] Second: Through a stable and repeatable crystal phase modulation method, the present invention can achieve stable crystal phase coupling between the o-phase and the t-phase, making it easier for the thin film to undergo rotation of the polarization direction or domain wall movement under an applied electric field, generating an ultra-high dielectric response, further enhancing the performance advantages of the device in high-density storage, and providing technical support for the development of the next-generation ferroelectric memory.

[0029] Third: The stacking design of the superlattice structure significantly reduces grain boundary defects, effectively truncates the conduction path, and reduces the leakage current density. Compared with traditional hafnium oxide-based ferroelectric thin films, the superlattice structure suppresses leakage current, further improving the stability of electrical properties and meeting the low-power requirements of high-performance memories.

[0030] Fourth: The superlattice structure improves the anti-fatigue ability of the thin film during polarization reversal, significantly extending the service life of the device. At the same time, the optimized thin film crystal structure and interface quality enhance the data retention performance, ensuring high reliability under long-term working conditions.

[0031] Fifth: The hafnium oxide-based ferroelectric thin film with a superlattice structure modulated by crystal phase has significant advantages in device applications. This method is highly compatible with existing CMOS processes, easy to integrate, reduces manufacturing costs and process complexity, and is suitable for various high-performance application scenarios such as non-volatile memories and logic devices, providing reliable support for the next-generation storage technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the steps included in the method for modulating the crystal phase of hafnium oxide-based ferroelectric based on the superlattice structure.

[0033] Figure 2 It is a schematic diagram corresponding to the structure when the hafnium oxide-based ferroelectric thin film is modulated to be dominated by the o-phase.

[0034] Figure 3 It is a schematic diagram corresponding to the structure when the hafnium oxide-based ferroelectric thin film is modulated to be dominated by the t-phase.

[0035] Figure 4 It is a schematic diagram corresponding to the structure when the hafnium oxide-based ferroelectric thin film is modulated to the o / t mixed phase.

[0036] Figure 5 It is the capacitance-voltage curve corresponding to the modulated o-phase, t-phase, and o / t mixed-phase hafnium oxide-based ferroelectric thin films.

[0037] In the figure: 1. Substrate, 2. Hafnium oxide layer, 3. Doped element layer, 4. Top metal electrode. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] In order to more clearly illustrate the purpose and advantages of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention.

[0039] Reference Figure 1As shown, on the one hand, it reflects the preparation process of hafnium oxide-based ferroelectric thin films, and on the other hand, it reflects the method for modulating the ferroelectric crystal phase of hafnium oxide-based based on the superlattice structure in the present invention. Specifically, the preparation process includes: preparing a substrate 1, depositing a hafnium oxide-based ferroelectric thin film, and sputtering a top metal electrode 4. Annealing can be further carried out after sputtering the top metal electrode 4 to complete crystallization. Among them, the hafnium oxide layer 2 and the doping element layer 3 are stacked to form a superlattice structure, and when the number of hafnium oxide layers 2 and doping element layers 3 is greater than 1, the two are stacked alternately.

[0040] The method for modulating the ferroelectric crystal phase of hafnium oxide-based based on the superlattice structure in the present invention is mainly reflected in that each hafnium oxide layer 2 in the hafnium oxide-based ferroelectric thin film is designed to be stacked by m hafnium oxide sub-layers, and each doping element layer 3 is designed to be stacked by n doping element sub-layers. By regulating the number of layers of the hafnium oxide layer 2 and the doping element layer 3, the number of their respective sub-layers, and the overall thickness, different stress effects will be caused, thereby realizing crystal phase modulation.

[0041] The crystal phase modulation of the present invention specifically refers to modulating the required crystal phase to be mainly the o-phase, mainly the t-phase, or the o / t mixed phase. When it is mainly the o-phase, control the range of m to be 2 ≤ m ≤ 10, and n = 1.5×m, as Figure 2 shown; when it is mainly the t-phase, control the range of m to be 20 ≤ m ≤ 30, and n = 2.5×m, as Figure 3 shown; when it is the o / t mixed phase, control the range of m to be 10 < m < 20, and n = 2×m, as Figure 4 shown.

[0042] After determining the values of m and n, the corresponding hafnium oxide layer 2 and doping element layer 3 can be deposited layer by layer alternately on the substrate 1 by atomic layer deposition technology, and each hafnium oxide layer 2 and doping element layer 3 are respectively deposited sub-layer by sub-layer by atomic layer deposition technology. After reaching the predetermined thickness, the top metal electrode 4 is grown by sputtering process, and the hafnium oxide-based ferroelectric thin film is crystallized after rapid thermal annealing.

[0043] The rapid thermal annealing of the present invention is carried out in a nitrogen atmosphere of 400 o °C to 650 o °C for 30 seconds to 10 minutes to complete the crystallization of the hafnium oxide-based ferroelectric thin film and stabilize the crystal phase.

[0044] Figure 5 are the capacitance-voltage curves corresponding to the o-phase, t-phase, and o / t mixed-phase hafnium oxide-based ferroelectric thin films modulated by the present invention. When the modulated thin film is the o-phase, the capacitance curve shows two peaks; when the modulated thin film is the t-phase, the capacitance curve shows four peaks; when the modulated thin film is the o / t mixed phase, the capacitance curve shows three peaks.

[0045] To make the above features and advantages more obvious and understandable, the present invention provides three embodiments of a method for modulating the ferroelectric crystal phase of hafnium oxide based on a superlattice structure:

[0046] Embodiment 1

[0047] A method for modulating the o-phase of an HZO thin film with a titanium nitride top metal electrode based on an Si substrate.

[0048] Step 1: Select a substrate.

[0049] Select intrinsic Si as Substrate 1.

[0050] Step 2: Deposit an o-phase HZO thin film with a superlattice structure.

[0051] Using atomic layer deposition technology, set the chamber vacuum to below 10 -6 Torr, set the chamber temperature to 280 o °C, and the source bottle temperatures are all 95 °C. Use tetrakis(dimethylamino)hafnium (TDMAH) as the hafnium source, tetrakis(dimethylamino)zirconium (TDMAZ) as the zirconium source, H2O as the oxygen source, and high-purity nitrogen as the carrier gas. The hafnium source pulse time is 2 s, the purge time is 5 s, the zirconium source pulse time is 1 s, the purge time is 10 s, the oxygen source pulse time is 0.3 s, and the purge time is 15 s. Grow 4 sub-layers of hafnium oxide and 6 sub-layers of zirconium oxide on the substrate in sequence. The zirconium oxide sub-layer is the doped element sub-layer, and keep cycling until the overall thickness of the HZO thin film reaches 10 nm.

[0052] Step 3: Grow the top metal electrode.

[0053] Using reactive sputtering technology, with a high-purity titanium target, under the conditions of a base vacuum of ≤ 5 × 10 -6 Torr, a working pressure of 5 × 10 -3 Torr, and a DC magnetron sputtering power of 300 W, reactively sputter a titanium nitride thin film with a thickness of 80 nm by introducing a mixed atmosphere of nitrogen and argon.

[0054] Step 4: Complete the crystallization of the HZO thin film.

[0055] Through rapid thermal annealing technology, in a nitrogen atmosphere at a temperature of 550 o °C, anneal for 5 minutes to complete the crystallization of the HZO thin film, stabilize the o-phase, and achieve the o-phase modulation of the HZO thin film.

[0056] Step 5: Conduct electrical performance tests to verify the o-phase.

[0057] Through capacitance-voltage curve testing, determine that the crystal phase corresponding to the modulated HZO thin film is the o-phase, as Figure 5 shown.

[0058] Embodiment 2

[0059] o / t Mixed Phase Modulation Method of Tantalum Nitride Top Metal Electrode Based on HAO Thin Film on Ge Substrate

[0060] Step 1: Select a substrate.

[0061] Select intrinsic Ge as substrate 1.

[0062] Step 2: Deposit the o / t mixed phase HAO thin film with a superlattice structure.

[0063] Using atomic layer deposition process, set the chamber vacuum below 10 -6 Torr, set the chamber temperature at 300 °C, the source bottle temperatures at 100 °C, use tetrakis(dimethylamino)hafnium (TDMAH) as the hafnium source, trimethylaluminum (Al(CH3)3) as the aluminum source, O3 as the oxygen source, high-purity argon as the carrier gas, the hafnium source pulse time at 1.5 s, the purge time at 6 s, the aluminum source pulse time at 1.2 s, the purge time at 8 s, the oxygen source pulse time at 0.5 s, the purge time at 10 s, and grow 12 sub-layers of hafnium oxide and 24 sub-layers of aluminum oxide on the substrate in sequence. The aluminum oxide sub-layers are the doped element sub-layers, and keep cycling until the overall thickness of the HAO thin film reaches 18 nm.

[0064] Step 3: Grow the top metal electrode.

[0065] Using reactive sputtering process, with a high-purity tantalum target, under the conditions of a base vacuum ≤ 5×10 -6 Torr, a working pressure of 6×10 -3 Torr, and a DC magnetron sputtering power of 280 W, reactively sputter a 100-nm-thick tantalum nitride top electrode by introducing a mixture of nitrogen and argon.

[0066] Step 4: Complete the crystallization of the HAO thin film.

[0067] Through rapid thermal annealing process, anneal for 3 minutes in a nitrogen atmosphere at a temperature of 650 °C to complete the crystallization of the HAO thin film, stabilize the o / t mixed phase, and achieve the o / t mixed phase modulation of the HAO thin film.

[0068] Step 5: Conduct electrical property tests to verify the o / t mixed phase.

[0069] Through capacitance-voltage curve tests, determine that the crystal phase corresponding to the modulated HAO thin film is the o / t mixed phase, as Figure 5 shown.

[0070] Example 3

[0071] t Phase Modulation Method of Tungsten Top Metal Electrode Based on HSO Thin Film on Metal Tungsten Substrate

[0072] Step 1: Select a substrate.

[0073] Select tungsten metal as Substrate 1.

[0074] Step 2: Deposit the t-phase HSO thin film with a superlattice structure.

[0075] Using the atomic layer deposition process, set the chamber vacuum to below 10 -6 Torr, set the chamber temperature to 310 °C, the source bottle temperatures are both 110 °C. Use tetrakis(dimethylamino)hafnium (TDMAH) as the hafnium source, trichlorosilane (SiHCl3) as the silicon source, N2O as the oxygen source, and high-purity helium as the carrier gas. The hafnium source pulse time is 2 s, the purge time is 14 s, the silicon source pulse time is 2.2 s, the purge time is 22 s, the oxygen source pulse time is 0.1 s, and the purge time is 20 s. Grow 20 sub-layers of hafnium oxide and 50 sub-layers of silicon oxide on the substrate in sequence. The silicon oxide sub-layer is the doped element sub-layer. Continuously cycle until the overall thickness of the HSO thin film reaches 21 nm.

[0076] Step 3: Grow the top metal electrode.

[0077] Using the reactive sputtering process, with a high-purity tungsten target, under the conditions of a base vacuum of ≤5×10 -6 Torr, a working pressure of 5.5×10 -3 Torr, and a DC magnetron sputtering power of 290 W, reactively sputter a 50-nm-thick tungsten metal top electrode by introducing a mixed atmosphere of nitrogen and helium.

[0078] Step 4: Complete the crystallization of the HSO thin film.

[0079] Through the rapid thermal annealing process, anneal for 10 minutes in a nitrogen atmosphere at a temperature of 600 °C to complete the crystallization of the HSO thin film, stabilize the t-phase, and achieve the t mixed-phase modulation of the HSO thin film;

[0080] Step 5: Conduct electrical performance tests to verify the t-phase.

[0081] Through capacitance-voltage curve testing, determine that the crystal phase corresponding to the modulated HSO thin film is the t-phase, as Figure 5 shown.

[0082] In summary, the present invention uses atomic layer deposition technology, introduces a superlattice structure, and realizes the modulation between the o-phase, t-phase, and o / t mixed-phase of hafnium oxide-based ferroelectric thin films by controlling the number and overall thickness of hafnium oxide layers and doped element layers under high vacuum, while significantly reducing the leakage current and enhancing the reliability of hafnium oxide-based ferroelectric thin films.

[0083] Based on the superlattice structure, the present invention utilizes atomic layer deposition technology to precisely modulate the crystal phase by controlling the number of hafnium oxide and dopant element layers and the overall thickness under high vacuum, providing a stable and reliable crystal phase modulation method, enabling the thin film to stably select ferroelectric or antiferroelectric properties according to different application scenarios, and improving the operational flexibility and applicability of hafnium-based ferroelectric thin films.

[0084] The present invention is not limited to the above best embodiments. The above description is only three specific examples of the present invention. Anyone can obtain other various forms of products under the inspiration of the present invention. However, no matter what changes are made in its shape or structure, as long as it has the same or similar technical solutions as the present application, it falls within the protection scope of the present invention.

Claims

1. A hafnium oxide-based ferroelectric crystal phase modulation method based on a superlattice structure, characterized in that: The hafnium oxide-based ferroelectric thin film is composed of a stack of k hafnium oxide layers (2) and k doped element layers (3), wherein each hafnium oxide layer (2) in the hafnium oxide-based ferroelectric thin film is designed to be composed of a stack of m hafnium oxide sub-layers, and each doped element layer (3) is designed to be composed of a stack of n doped element sub-layers; The hafnium oxide layer (2) and the doped element layer (3) are stacked to form the superlattice structure; The crystal phase modulation is to modulate the hafnium oxide-based ferroelectric crystal phase to be dominated by the o phase, dominated by the t phase, or an o / t mixed phase by determining the values ​​of m and n, and the method is as follows: By volume, when the o phase content is greater than 60%, the o phase is dominant, 2≤m≤10, n=1.5×m; when the t phase content is greater than 60%, the t phase is dominant, 20≤m≤30, n=2.5×m; when the difference between the o phase content and the t phase content does not exceed 20%, it is an o / t mixed phase, 10<m<20, n=2×m; where m is an even number.

2. The hafnium oxide-based ferroelectric crystal phase modulation method based on a superlattice structure according to claim 1, characterized in that: The hafnium oxide-based ferroelectric thin film is arranged between a substrate (1) and a top metal electrode (4) to form a ferroelectric capacitor, wherein the upper side of the substrate (1) is a hafnium oxide layer (2), and the lower side of the top metal electrode (4) is a doped element layer (3), and when k≥2, the hafnium oxide layer (2) and the doped element layer (3) are alternately stacked.

3. The hafnium oxide-based ferroelectric crystal phase modulation method based on a superlattice structure according to claim 2, characterized in that: The thickness of each of the doped element sub-layers is 0.08 nm-0.12 nm, and the thickness of each of the hafnium oxide sub-layers is 0.08 nm-0.12 nm.

4. The hafnium oxide-based ferroelectric crystal phase modulation method based on a superlattice structure according to claim 2, characterized in that: The top metal electrode (4) is grown on the last stacked doping element layer (3) by a sputtering process, and then annealed for 30 seconds to 10 minutes in a nitrogen atmosphere at 400° C. to 650° C. to complete crystallization.

5. The hafnium oxide-based ferroelectric crystal phase modulation method based on a superlattice structure according to claim 2, characterized in that: Each of the hafnium oxide layers (2) is prepared by an atomic layer deposition process, the method being as follows: Under vacuum environment, a hafnium source, an oxygen source and a carrier gas are set, and the pulse time of the hafnium source is set to 0.5-10 s, the purge time is set to 5-30 s, the pulse time of the oxygen source is set to 0.1-2.5 s, and the purge time is set to 8-40 s, and m hafnium oxide sublayers are grown in sequence; Each of the doped element layers (3) is prepared by an atomic layer deposition process, the method being as follows: Under a vacuum environment, set a doping element source, an oxygen source and a carrier gas, set the doping element source pulse time to 1-8s, the purge time to 5-25s, the oxygen source pulse time to 0.1-2.5s, the purge time to 8-40s, and sequentially grow n doping element sublayers.

6. The hafnium oxide-based ferroelectric crystal phase modulation method based on a superlattice structure according to claim 5, characterized in that: In the atomic layer deposition process, the chamber temperature is set to 200° C.~350° C.

7. The hafnium oxide-based ferroelectric crystal phase modulation method based on a superlattice structure according to claim 5, characterized in that: The oxygen source is water, ozone, oxygen, hydrogen peroxide or nitrogen oxides; the carrier gas is nitrogen, argon, helium, hydrogen or a nitrogen-hydrogen mixed gas.

8. The hafnium oxide-based ferroelectric crystal phase modulation method based on a superlattice structure according to claim 5, characterized in that: The hafnium source is tetrakis(dimethylamino)hafnium; the doping element source is tri(methylcyclopentadienyl)yttrium, trimethylmethoxysilane, trimethylaluminum, tetraisopropoxytitanium, tris[bis(trimethylsilyl)amino]lanthanum, tetramethylpimelate strontium, bis(trimethylsilyl)amine scandium, trifluoromethanesulfonate or tetrakis(dimethylamino)zirconium; accordingly, the material of the doping element layer (3) is yttrium oxide, silicon oxide, aluminum oxide, titanium oxide, lanthanum oxide, strontium oxide, scandium oxide, cerium oxide or zirconium oxide.

9. The hafnium oxide-based ferroelectric crystal phase modulation method based on a superlattice structure according to claim 2, characterized in that: The substrate (1) is a semiconductor substrate or a metal substrate, and has a thickness greater than 15 nm.

10. The hafnium oxide-based ferroelectric crystal phase modulation method based on a superlattice structure according to claim 2, characterized in that: The material of the top metal electrode (4) is metal tungsten, metal titanium, metal copper, metal aluminum, metal platinum, metal iridium, metal ruthenium, tungsten nitride, titanium nitride, tantalum nitride, iridium oxide, ruthenium oxide, tungsten carbide, titanium carbide, tungsten silicide, titanium silicide or tantalum silicide, and the thickness is greater than 15nm.

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