Hafnium oxide-based ferroelectric crystal phase modulation method based on superlattice structure

Abstract

According to the hafnium oxide-based ferroelectric crystal phase modulation method based on the superlattice structure, each hafnium oxide layer in a hafnium oxide-based ferroelectric film is designed to be formed by stacking m hafnium oxide sub-layers, and each doped element layer is designed to be formed by stacking n doped element sub-layers; the hafnium oxide layer and the doping element layer are stacked to form a superlattice structure, and the hafnium oxide-based ferroelectric crystal phase is modulated as o phase dominant, t phase dominant or o / t mixed phase by determining the values of m and n, and the method is as follows: by volume, when the content of o phase is greater than 60%, o phase dominant, m is greater than or equal to 2 and less than or equal to 10, and n is 1.5 * m; when the content of the t phase is greater than 60%, the t phase is dominant, m is greater than or equal to 20 and less than or equal to 30, and n is equal to 2.5 * m; when the difference between the content of the o phase and the content of the t phase does not exceed 20%, the phase is an o / t mixed phase, m is more than 10 and less than 20, and n is equal to 2 * m; wherein m is an even number. According to the invention, the crystalline phase of the hafnium oxide-based ferroelectric film can be modulated, the electric leakage is extremely low, and the reliability is high.

Description

Technical Field

[0001] The invention belongs to the technical field of microelectronic devices, and particularly relates to a hafnium oxide-based ferroelectric crystal phase modulation method 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 placed on the storage density, access speed and number of operations of memory. Hafnium oxide-based ferroelectric films can be widely used in a variety of functional memory devices due to their excellent ferroelectric and antiferroelectric properties. In addition, the excellent CMOS process compatibility of hafnium oxide-based ferroelectric films makes them gradually become the key material for the next generation of memory 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). Usually, the paraelectric properties of hafnium oxide-based ferroelectric films are mainly m phase, the ferroelectric properties are mainly o phase, and the antiferroelectric properties are mainly t phase. In practical applications of memory, ferroelectric or antiferroelectric properties of the film are usually required, and the m phase is suppressed as much as possible. When the crystal phase of the film is in a mixed state of o phase and t phase, the film can produce extremely high dielectric response, which is conducive to high-density storage of memory. To this end, for different application requirements, crystal phase modulation of hafnium oxide-based ferroelectric films is an indispensable means.

[0004] However, the current traditional hafnium oxide-based ferroelectric thin 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, the crystal phase modulation by only changing the ratio of hafnium oxide and other ferroelectric doping elements through monolayer growth will form a solid solution inside, and the device performance will be unstable due to the uneven distribution of the internal crystal phase. In addition, the leakage and reliability issues of hafnium oxide-based ferroelectric thin films also seriously limit their application in low-power and high-reliability memory devices. Summary of the invention

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

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: A hafnium oxide-based ferroelectric crystal phase modulation method based on a superlattice structure, wherein each hafnium oxide layer in a hafnium oxide-based ferroelectric thin film is designed to be composed of m hafnium oxide sublayers stacked, and each doped element layer is designed to be composed of n doped element sublayers stacked; the hafnium oxide layer and the doped element layer are stacked to form the superlattice structure.

[0007] 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 in the hafnium oxide-based ferroelectric film is closely related to the film crystal phase structure, and its role is mainly reflected in the lattice stress, energy barrier, and interlayer interface effect. Therefore, the crystal phase modulation of the present invention 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.

[0008] Specifically, when 2≤m≤10, n=1.5×m, the doping elements introduce lattice distortion. At this time, the proportion of doping elements is relatively small, which can stabilize the hafnium oxide-based ferroelectric film in the o phase but make it difficult to cross the o / t phase energy barrier. The compressive stress between layers also promotes the stability of the o phase, ensuring that the o phase is dominant. The present invention defines that when the o phase is dominant, the o phase content is greater than 60% by volume.

[0009] When 20≤m≤30, n=2.5×m, the interlayer stress effect caused by the higher doping element ratio and the increase in single layer thickness is greatly weakened, allowing the film to cross the potential barrier between the o / t phase and stabilize in the t phase, ensuring that the t phase is dominant. The present invention defines that when the t phase is dominant, the t phase content is greater than 60% by volume.

[0010] When 10<m<20, n=2×m, the t phase caused by the introduction of doping elements competes with the o phase of hafnium oxide, the interlayer stress leads to the generation of a polymorphic phase boundary, the energy barrier between the o / t phase is greatly weakened, the two phases are mixed to form an o / t mixed phase, and the dielectric properties of the hafnium-based ferroelectric film are significantly improved. When the present invention defines the o / t mixed phase, the difference between the o phase content and the t phase content by volume does not exceed 20%.

[0011] Obviously, in order to ensure that n is an integer, in the present invention, under the premise of meeting the range requirement, m should be an even number.

[0012] Therefore, the hafnium oxide-based ferroelectric crystal phase modulation method based on the superlattice structure of the present invention can effectively improve the interface quality and material uniformity by adopting a periodic superlattice structure in the hafnium oxide-based ferroelectric film, realize the crystal phase modulatable and leakage characteristics and reliability performance optimization, and obtain a high-reliability film. On the one hand, since the superlattice structure cuts off the conductive path, a low leakage film is realized. On the other hand, the superlattice structure introduces interlayer stress between the hafnium oxide layer and the doped element layer. By adjusting the number of hafnium oxide and doped element layers and the overall thickness, different stress effects will be caused, thereby realizing crystal phase modulation.

[0013] In one embodiment, the hafnium oxide-based ferroelectric film is composed of a stack of k hafnium oxide layers and k doped element layers. The hafnium oxide-based ferroelectric film is arranged between a substrate and a top metal electrode to form a ferroelectric capacitor, wherein the upper side of the substrate is a hafnium oxide layer, and the lower side of the top metal electrode is a doped element layer. When k≥2, the hafnium oxide layers and the doped element layers are stacked alternately.

[0014] In one embodiment, the thickness of each of the doped element sublayers is 0.08nm-0.12nm, and the thickness of each of the hafnium oxide sublayers is 0.08nm-0.12nm. Generally, the total thickness of the hafnium oxide-based ferroelectric film is 10nm-30nm, and can be selected to fluctuate within a small range according to the number of hafnium oxide sublayers and doped element sublayers.

[0015] In one embodiment, the top metal electrode is grown on the last stacked doping element layer by a sputtering process, and then annealed in a nitrogen atmosphere at 400° C. to 650° C. for 30 seconds to 10 minutes to complete crystallization.

[0016] In one embodiment, each of the hafnium oxide layers is prepared by an atomic layer deposition process 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 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.

[0017] In one embodiment, in the atomic layer deposition process, the chamber temperature is set to 200° C. to 350° C.

[0018] 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.

[0019] In one embodiment, the hafnium source is tetrakis(dimethylamino)hafnium; the doping element source is tris(methylcyclopentadienyl)yttrium, trimethylmethoxysilane, trimethylaluminum, tetraisopropoxytitanium, tris[bis(trimethylsilyl)amino]lanthanum, tetramethylpimelate strontium, bis(trimethylsilyl)amine scandium, trifluoromethanesulfonate cerium or tetrakis(dimethylamino)zirconium, and accordingly, the material of the doping element layer is yttrium oxide, silicon oxide, aluminum oxide, titanium oxide, lanthanum oxide, strontium oxide, scandium oxide, cerium oxide or zirconium oxide. The hafnium oxide-based ferroelectric thin film is represented by HYO, HSO, HAO, HTO, HLO, HSrO, HScO, HCaO. Among them, HYO is yttrium-doped hafnium oxide, HSO is silicon-doped hafnium oxide, HAO is aluminum-doped hafnium oxide, HTO is titanium-doped hafnium oxide, HLO is lanthanum-doped hafnium oxide, HSrO is strontium-doped hafnium oxide, HScO is scandium-doped hafnium oxide, and HCaO is cerium-doped hafnium oxide.

[0020] In one embodiment, the substrate is a semiconductor substrate or a metal substrate with a thickness greater than 15 nm. Typical semiconductor substrates include Si, Ge, SiGe, GaN, GaAs and SiC, and typical metal substrates include 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 and tantalum silicide, and the present invention can select according to the needs.

[0021] In one embodiment, the material of the top metal electrode 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. The present invention can be selected according to needs and the thickness is greater than 15nm.

[0022] Compared with the prior art, the present invention has the following beneficial effects: First: The present invention is based on a superlattice structure. By adjusting the number of hafnium oxide sublayers and doped element sublayers, the crystal phase can be accurately, stably and reliably modulated, so that the film can stably select ferroelectric properties or antiferroelectric properties according to different application scenarios, thereby improving the operational flexibility and applicability of hafnium oxide-based ferroelectric films.

[0023] Second: The present invention can achieve stable crystal phase coupling between the O phase and the T phase through a stable and repeatable crystal phase modulation method, making it easier for the film to rotate in the polarization direction or move the domain wall under an external electric field, resulting in an ultra-high dielectric response, further enhancing the performance advantage of the device in high-density storage, and providing technical support for the development of the next generation of ferroelectric memory.

[0024] Third: The stacking design of the superlattice structure significantly reduces grain boundary defects, effectively cuts off the conductive path, and reduces the leakage current density. Compared with traditional hafnium oxide-based ferroelectric films, the superlattice structure suppresses leakage current, further improves the stability of electrical performance, and meets the requirements of high-performance memory for low power consumption.

[0025] Fourth: The superlattice structure improves the anti-fatigue ability of the film during polarization reversal, significantly extending the service life of the device. At the same time, the optimized film crystal structure and interface quality enhance the data retention performance and ensure high reliability under long-term working conditions.

[0026] Fifth: The hafnium oxide-based ferroelectric thin film with crystal phase modulation 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 a variety of high-performance application scenarios such as non-volatile memory and logic devices, providing reliable support for the next generation of storage technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the steps included in the hafnium oxide-based ferroelectric crystal phase modulation method based on a superlattice structure.

[0028] Figure 2 Schematic diagram of the structure corresponding to when the hafnium oxide-based ferroelectric film is modulated to have the o-phase dominant.

[0029] Figure 3 Schematic diagram of the structure corresponding to when the hafnium oxide-based ferroelectric film is modulated to have the t phase dominant.

[0030] Figure 4 Schematic diagram of the structure corresponding to modulating the hafnium oxide-based ferroelectric film into an o / t mixed phase.

[0031] Figure 5 The capacitance-voltage curves corresponding to the modulated o-phase, t-phase and o / t mixed-phase hafnium oxide-based ferroelectric films.

[0032] In the figure: 1, substrate, 2, hafnium oxide layer, 3, doped element layer, 4, top metal electrode. DETAILED DESCRIPTION

[0033] 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.

[0034] refer to Figure 1As shown, on the one hand, it embodies the preparation process of the hafnium oxide-based ferroelectric film, and on the other hand, it embodies the hafnium oxide-based ferroelectric crystal phase modulation method based on the superlattice structure of the present invention. Specifically, its preparation process includes: preparing a substrate 1, depositing a hafnium oxide-based ferroelectric film and sputtering a top metal electrode 4. And further annealing can be performed after sputtering the top metal electrode 4 to complete crystallization. Among them, the hafnium oxide layer 2 and the doped element layer 3 are stacked to form a superlattice structure, and when the number of the hafnium oxide layer 2 and the doped element layer 3 is greater than 1, the two are alternately stacked.

[0035] The hafnium oxide-based ferroelectric crystal phase modulation method based on the superlattice structure of the present invention is mainly embodied in that each hafnium oxide layer 2 in the hafnium oxide-based ferroelectric thin film is designed to be stacked by m hafnium oxide sublayers, and each doped element layer 3 is designed to be stacked by n doped element sublayers. By adjusting the number of hafnium oxide layers 2 and doped element layers 3, the number of their respective sublayers and the overall thickness, different stress effects will be caused, thereby achieving crystal phase modulation.

[0036] The crystal phase modulation of the present invention specifically refers to that the crystal phase required for modulation is dominated by the o phase, dominated by the t phase or an o / t mixed phase. When the o phase is dominant, the range of m is controlled to be 2≤m≤10, n=1.5×m, such as Figure 2 As shown; when the t phase is dominant, the range of controlling m is 20≤m≤30, n=2.5×m, as Figure 3 As shown; when it is an o / t mixed phase, the range of m is controlled to be 10<m<20, n=2×m, such as Figure 4 shown.

[0037] After determining the values ​​of m and n, the corresponding hafnium oxide layer 2 and the doped element layer 3 can be alternately deposited layer by layer on the substrate 1 by using the atomic layer deposition process, wherein each hafnium oxide layer 2 and the doped element layer 3 are deposited sub-layer by sub-layer by using the atomic layer deposition process. After reaching a predetermined thickness, the top metal electrode 4 is grown by the sputtering process, and the hafnium oxide-based ferroelectric film is crystallized after rapid thermal annealing.

[0038] The rapid thermal annealing of the present invention is carried out at 400 o C~650 o C in a nitrogen atmosphere and annealing for 30 seconds to 10 minutes to complete the crystallization of the hafnium oxide-based ferroelectric film and stabilize the crystal phase.

[0039] Figure 5 The capacitance-voltage curves corresponding to the hafnium oxide-based ferroelectric thin films of the o-phase, t-phase and o / t mixed phase after modulation by the present invention are shown. When the modulated thin film is in the o-phase, the capacitance curve presents two peaks; when the modulated thin film is in the t-phase, the capacitance curve presents four peaks; when the modulated thin film is in the o / t mixed phase, the capacitance curve presents three peaks.

[0040] In order to make the above features and advantages more obvious and easy to understand, the present invention provides three embodiments of the hafnium oxide-based ferroelectric crystal phase modulation method based on the superlattice structure: Example 1 O-phase modulation method based on titanium nitride top metal electrode of HZO thin film on Si substrate.

[0041] Step 1: Select the substrate.

[0042] Intrinsic Si was selected as substrate 1 .

[0043] Step 2: Depositing superlattice structured o-phase HZO thin film.

[0044] Using the atomic layer deposition process, the chamber vacuum is set to 10 -6 Torr or less, set the chamber temperature to 280 o C, the temperature of the source bottle is 95°C, tetrakis(dimethylamino)hafnium (TDMAH) is used as the hafnium source, tetrakis(dimethylamino)zirconium (TDMAZ) is used as the zirconium source, H2O is used as the oxygen source, the carrier gas is high-purity nitrogen, the hafnium source pulse time is 2s, the purge time is 5s, the zirconium source pulse time is 1s, the purge time is 10s, the oxygen source pulse time is 0.3s, the purge time is 15s, and 4 hafnium oxide sublayers and 6 zirconium oxide sublayers are grown on the substrate in sequence. The zirconium oxide sublayer is the doped element sublayer, and the cycle is continued until the overall thickness of the HZO film reaches 10nm.

[0045] Step 3: Growing the top metal electrode.

[0046] Using reactive sputtering technology, high-purity titanium target material, the substrate vacuum degree is ≤5×10 -6 Torr, working pressure 5×10 -3 Under the conditions of 300W DC magnetron sputtering power, a titanium nitride film with a thickness of 80nm was reactively sputtered by introducing a mixed atmosphere of nitrogen and argon.

[0047] Step 4: Complete HZO thin film crystallization.

[0048] Through rapid thermal annealing process, at a temperature of 550 o C in a nitrogen atmosphere and anneal for 5 minutes to complete the crystallization of the HZO film, stabilize the o-phase, and achieve o-phase modulation of the HZO film.

[0049] Step 5: Conduct electrical performance test to verify the o phase.

[0050] Through the capacitance-voltage curve test, it is determined that the crystal phase corresponding to the modulated HZO film is o phase, such as Figure 5 shown.

[0051] Example 2 O / T mixed phase modulation method based on tantalum nitride top metal electrode of HAO thin film on Ge substrate.

[0052] Step 1: Select the substrate.

[0053] Intrinsic Ge is selected as substrate 1 .

[0054] Step 2: Depositing superlattice structure o / t mixed phase HAO film.

[0055] Using the atomic layer deposition process, the chamber vacuum is set to 10 -6 Torr or less, set the chamber temperature to 300℃, the source bottle temperature to 100℃, use tetrakis(dimethylamino)hafnium (TDMAH) as the hafnium source, trimethylaluminum (Al(CH3)3) as the aluminum source, O3 as the oxygen source, the carrier gas is high-purity argon, the hafnium source pulse time is 1.5s, the purge time is 6s, the aluminum source pulse time is 1.2s, the purge time is 8s, the oxygen source pulse time is 0.5s, the purge time is 10s, and 12 hafnium oxide sublayers and 24 aluminum oxide sublayers are grown on the substrate in sequence. The aluminum oxide sublayer is the doped element sublayer, and the cycle is continued until the overall thickness of the HAO film reaches 18nm.

[0056] Step 3: Growing the top metal electrode.

[0057] Using reactive sputtering technology, high purity tantalum target material, the substrate vacuum degree is ≤5×10 -6 Torr, working pressure 6×10 -3 Under the conditions of 3000 Torr and DC magnetron sputtering power of 280W, a metal tantalum nitride top electrode with a thickness of 100nm was reactively sputtered by introducing a mixture of nitrogen and argon.

[0058] Step 4: Complete HAO thin film crystallization.

[0059] Through the rapid thermal annealing process, annealing is performed at a temperature of 650°C in a nitrogen atmosphere for 3 minutes to complete the crystallization of the HAO film, stabilize the o / t mixed phase, and achieve o / t mixed phase modulation of the HAO film.

[0060] Step 5: Conduct electrical performance test to verify the o / t mixed phase.

[0061] Through the capacitance-voltage curve test, it is determined that the crystal phase corresponding to the modulated HAO film is an o / t mixed phase, such as Figure 5 shown.

[0062] Example 3 T-phase modulation method based on tungsten top metal electrode of HSO thin film on metal tungsten substrate.

[0063] Step 1: Select the substrate.

[0064] Metal tungsten was selected as the substrate 1 .

[0065] Step 2: Depositing a superlattice structured t-phase HSO film.

[0066] Using the atomic layer deposition process, the chamber vacuum is set to 10 -6 Torr or less, set the chamber temperature to 310℃, the source bottle temperature to 110℃, use tetrakis(dimethylamino)hafnium (TDMAH) as the hafnium source, trichlorosilane (SiHCl3) as the silicon source, N2O as the oxygen source, and the carrier gas to high-purity helium. The hafnium source pulse time is 2s, and the purge time is 14s. The silicon source pulse time is 2.2s, and the purge time is 22s. The oxygen source pulse time is 0.1s, and the purge time is 20s. Then, 20 hafnium oxide sublayers and 50 silicon oxide sublayers are grown on the substrate in sequence. The silicon oxide sublayer is the doped element sublayer, and the cycle is continued until the overall thickness of the HSO film reaches 21nm.

[0067] Step 3: Growing the top metal electrode.

[0068] Using reactive sputtering technology, high purity tungsten target material, the substrate vacuum degree is ≤5×10 -6 Torr, working pressure 5.5×10 -3 Under the conditions of 0.3777 W and DC magnetron sputtering power of 290 W, a metal tungsten top electrode with a thickness of 50 nm was reactively sputtered by introducing a mixed atmosphere of nitrogen and helium.

[0069] Step 4: Complete HSO thin film crystallization.

[0070] Through the rapid thermal annealing process, annealing is performed at a temperature of 600°C in a nitrogen atmosphere for 10 minutes to complete the crystallization of the HSO film, stabilize the t phase, and achieve t mixed phase modulation of the HSO film; Step 5: Conduct electrical performance test to verify the t phase.

[0071] Through the capacitance-voltage curve test, it is determined that the crystal phase corresponding to the modulated HSO film is the t phase, such as Figure 5 shown.

[0072] In summary, the present invention utilizes atomic layer deposition technology, introduces a superlattice structure, and achieves modulation of the hafnium oxide-based ferroelectric film between the o phase, t phase, and o / t mixed phase by regulating the number and overall thickness of the hafnium oxide layer and the doped element layer under high vacuum. At the same time, the leakage current is significantly reduced, and the reliability of the hafnium oxide-based ferroelectric film is enhanced.

[0073] The present invention is based on a superlattice structure and utilizes atomic layer deposition technology. By adjusting the number of hafnium oxide and doping element layers and the overall thickness under high vacuum, the crystal phase can be precisely modulated, providing a stable and reliable crystal phase modulation method, so that the film can stably select ferroelectric properties or antiferroelectric properties according to different application scenarios, thereby improving the operational flexibility and applicability of hafnium oxide-based ferroelectric films.

[0074] The present invention is not limited to the above-mentioned optimal implementation mode. The above descriptions are only three specific examples of the present invention. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all those with the same or similar technical solutions as the present application fall 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: Each hafnium oxide layer (2) in the hafnium oxide-based ferroelectric thin film is designed to be composed of m hafnium oxide sub-layers stacked, and each doped element layer (3) is designed to be composed of n doped element sub-layers stacked; 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 film is composed of a stack of k hafnium oxide layers (2) and k doped element layers (3); the hafnium oxide-based ferroelectric 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); when k≥2, the hafnium oxide layers (2) and the doped element layers (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.

Images