A hafnium oxide-based ferroelectric thin film, a preparation method and applications thereof

Abstract

The application relates to the field of ferroelectric thin film technology preparation, and particularly discloses a hafnium oxide-based ferroelectric thin film, a preparation method and application. The preparation method of the hafnium oxide-based ferroelectric thin film comprises the following steps: substrate pretreatment: cleaning the substrate by using an organic solvent; deposition of a bottom electrode: depositing the bottom electrode on the substrate by using a physical vapor deposition method; deposition of an HZO thin film: depositing the HZO thin film on the bottom electrode by using a pulsed laser deposition method; deposition of a cover layer: depositing the cover layer on the HZO thin film by using the pulsed laser deposition method; annealing: introducing 20-80 mTorr oxygen into a high temperature of 400-800 DEG C, keeping for 3-30 min, and then cooling the thin film sample to room temperature; deposition of a top electrode: depositing the top electrode on the cover layer by using the physical vapor deposition method, so as to form the hafnium oxide-based ferroelectric thin film. The hafnium oxide-based ferroelectric thin film can be used for manufacturing a negative capacitance field effect transistor, and has the characteristics of excellent ferroelectricity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ferroelectric thin film, more particularly, it relates to a hafnium oxide-based ferroelectric thin film, a preparation method and application. BACKGROUND

[0002] Ferroelectricity refers to a kind of material with two or more spontaneous polarization states, and the spontaneous polarization can be reversed under the action of external electric field, and the spontaneous polarization still exists after the external electric field is removed.

[0003] With the rapid development of social media and mobile device technology, electronic components all follow the development law of "Moore's Law", and develop towards miniaturization and integration, and ferroelectric thin films also evolve towards miniaturization.

[0004] At present, the most widely used ferroelectric thin film material is perovskite-based ferroelectric thin film, such as lead zirconate titanate, barium titanate, strontium bismuth tantalate, etc. Although they have the advantage of large remanent polarization, they also have disadvantages, such as Pb pollution to the environment, disappearance of ferroelectricity at nanoscale and inability to miniaturize, poor ability to resist hydrogenation and other complex environments, and incompatibility with CMOS process, etc. Therefore, it is urgent to develop new ferroelectric thin film materials that are environmentally friendly, high-performance, small in thickness, and compatible with existing processes to replace traditional perovskite-based materials.

[0005] The hafnium oxide-based ferroelectric thin film not only solves the problems in the above-mentioned technology, but also has good electrical properties and thermal stability in nanoscale, and is considered as an ideal insulating gate material. However, the hafnium oxide-based ferroelectric thin film has the defect of poor ferroelectricity performance. SUMMARY

[0006] In order to improve the problem of poor ferroelectricity performance of the hafnium oxide-based ferroelectric thin film, the present application provides a hafnium oxide-based ferroelectric thin film, a preparation method and application.

[0007] In a first aspect, the present application provides a preparation method of a hafnium oxide-based ferroelectric thin film, comprising the following steps:

[0008] Substrate pretreatment: the substrate is cleaned with an organic solvent;

[0009] Bottom electrode deposition: a physical vapor deposition method is used to deposit a bottom electrode on the substrate;

[0010] Deposition of HZO thin film: a pulsed laser deposition method is used to deposit a HZO thin film on the bottom electrode, the deposition temperature is set to 400-550℃, the number of excitation light is 2000-6500, and the thickness of the formed HZO thin film is 4-20nm;

[0011] Cover layer deposition: a cover layer is deposited on the HZO film by pulse laser deposition, the deposition temperature is set to 400-500℃, the number of excitation light is set to 6000-20000, so that the thickness of the formed cover layer is 8-30nm, and the thin film sample is formed after deposition;

[0012] Annealing: 20-80mTorr oxygen is introduced at a high temperature of 400-800℃, and the thin film sample is cooled to room temperature after being maintained for 3-30min;

[0013] Top electrode deposition: a top electrode is deposited on the cover layer by physical vapor deposition to form a hafnium oxide-based ferroelectric thin film.

[0014] By adopting the above technical solution, the HZO film material has ferroelectricity, the HZO film is deposited between the bottom electrode and the cover layer, the thermal expansion coefficient of the bottom electrode is used to provide strain to regulate the ferroelectricity of the HZO film, the cover layer provides clamping stress to improve the ferroelectricity and reliability of the HZO film; at the same time, during the annealing process, 20-80mTorr oxygen pressure is used, and under this oxygen pressure range, the ferroelectricity of the ferroelectric thin film can be further enhanced.

[0015] Optionally, 10-100mTorr oxygen is introduced during the pulse laser deposition process of forming the HZO film, and 80-200mTorr oxygen is introduced during the pulse laser deposition process of forming the cover layer.

[0016] By adopting the above technical solution, oxygen is introduced into the HZO film and the cover layer, and different contents of oxygen are introduced during the deposition process to form oxygen vacancies, which can better enhance the ferroelectricity of the ferroelectric thin film.

[0017] Optionally, the pulse laser deposition temperature of the HZO film is set to 450-500℃, and the number of excitation light is set to 2000-6000, so that the thickness of the prepared HZO film is 4-10nm; the pulse laser deposition temperature of the cover layer is set to 450-500℃, and the number of excitation light is set to 6000-18000, so that the thickness of the prepared cover layer is 10-30nm.

[0018] By adopting the above technical solution, the number of excitations in the pulse laser deposition process is regulated to further adjust the thickness of the HZO film and the cover layer, and the temperature in the pulse laser deposition process is changed to understand the influence of temperature on the crystallization of the HZO film and the cover layer. Through experiments, it is found that when the temperature is low, the crystallization performance of the HZO film and the cover layer is good.

[0019] Optionally, the pulse laser power of the HZO thin film and the cover layer is 1.5-2W, the laser frequency is 5-9.9Hz, the aperture size is 0.5, the aperture distance is-30cm, and the target distance is 3-5cm.

[0020] By adopting the above technical scheme, the size of the plume formed by laser ablation of the target material can be adjusted under the laser parameters, so as to control the growth of the HZO thin film and the cover layer.

[0021] Optionally, the bottom electrode is a TiN electrode.

[0022] Optionally, the physical vapor deposition method is magnetron sputtering, the magnetron sputtering power is 200-300W, and the sputtering time is 1-2h.

[0023] By adopting the above technical scheme, magnetron sputtering can realize large-area deposition, so as to ensure that the film composition and structure of the bottom electrode or the top electrode are consistent.

[0024] Optionally, the cover layer is an Al2O3 thin film.

[0025] Optionally, the thickness of the Al2O3 thin film is 20-30nm.

[0026] Preferably, the deposition state of the Al2O3 thin film is amorphous.

[0027] By adopting the above technical scheme, since the Al2O3 thin film is deposited on the HZO thin film, when the thickness of the Al2O3 thin film is less than 20nm or greater than 30nm, the ferroelectricity of the HZO thin film will be reduced. In addition to serving as a cover layer, the Al2O3 thin film can also serve as an insulating layer, especially when the deposition state is amorphous, the leakage current of the film structure can be inhibited, and the ferroelectricity of the HZO thin film is further improved.

[0028] Optionally, the thickness of the HZO thin film is 4.3-10nm.

[0029] By adopting the above technical scheme, when the thickness is less than 4nm, the ferroelectricity of the hafnium oxide-based ferroelectric film formed finally will be poor; when the thickness is greater than 10nm, it is not conducive to the integration of the CMOS process, and the advantages of the hafnium oxide-based ferroelectric film, which is thin and has ferroelectricity, cannot be realized.

[0030] Optionally, the substrate is a silicon wafer, preferably a p-type silicon wafer.

[0031] By adopting the above technical scheme, the silicon wafer can be better compatible with the CMOS process, and the p-type silicon wafer has a specific crystal face that can provide a corresponding lattice mismatch stress, thereby affecting the growth of the thin film.

[0032] Optionally, the top electrode is an Au electrode.

[0033] In a second aspect, the application provides a hafnium oxide-based ferroelectric thin film prepared by the hafnium oxide-based ferroelectric thin film preparation method.

[0034] By adopting the technical scheme, the hafnium oxide-based ferroelectric thin film prepared has excellent ferroelectric properties and can be adjusted according to actual needs.

[0035] In a third aspect, the application provides an application of the hafnium oxide-based ferroelectric thin film, which is mainly applied to the manufacture of a negative capacitance field effect transistor.

[0036] In summary, the application has at least one of the following beneficial technical effects:

[0037] 1. The method of the application adopts a HZO thin film with good ferroelectricity, deposits the HZO thin film between the bottom electrode and the cover layer, uses appropriate thermal expansion coefficients and clamping stress to induce the HZO thin film to form ferroelectricity, and thus has stronger ferroelectricity. Meanwhile, 20-80 mTorr oxygen is added in the annealing step to further enhance the ferroelectricity of the hafnium oxide-based ferroelectric thin film. Through verification, when the oxygen pressure is 80 mTorr, the Pr value is 2, and the ferroelectricity is the best.

[0038] 2. The application adds oxygen in the pulsed laser deposition. Specifically, 10-100 mTorr oxygen is added in the deposition step of the HZO thin film, 80-200 mTorr oxygen is added in the deposition step of the Al2O3 thin film, and 20-80 mTorr oxygen is added in the annealing step. When oxygen is used in each step, oxygen vacancies are formed, which is conducive to enhancing the ferroelectricity of the hafnium oxide-based ferroelectric thin film.

[0039] 3. The application controls the number of excitations or the temperature in the HZO thin film deposition process or the Al2O3 thin film deposition process, thereby controlling the thickness of the HZO thin film and the Al2O3 thin film. The thickness is further adjusted to verify the influence on the ferroelectricity of the hafnium oxide-based ferroelectric thin film. The results show that: when the number of excitations used in the HZO thin film deposition process is smaller, the thickness of the formed HZO thin film is also smaller, and the ferroelectricity of the finally prepared hafnium oxide-based ferroelectric thin film is better. When the temperature used in the Al2O3 thin film deposition process is between 450-500℃, and the thickness of the formed Al2O3 thin film is controlled to be between 10-30 nm, the ferroelectricity of the finally prepared hafnium oxide-based ferroelectric thin film is also better, and can be applied to the manufacture of a negative capacitance field effect transistor. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a flowchart of the hafnium oxide-based ferroelectric thin film preparation method provided by the application;

[0041] Figure 2are atomic force microscope and piezoelectric force microscope images of hafnium oxide-based ferroelectric thin films and corresponding phase and amplitude images;

[0042] Figure 3 are leakage current curve comparison diagrams of a hafnium oxide-based ferroelectric thin film with an Al2O3 thin film added in a deposition step and a hafnium oxide-based ferroelectric thin film without an Al2O3 thin film added in a deposition step;

[0043] Figure 5 are P-V curve diagrams of examples 1-9 of a hafnium oxide-based ferroelectric thin film;

[0044] Figure 4 are P-V curve diagrams of examples 1, 10, and comparative example 1 of a hafnium oxide-based ferroelectric thin film;

[0045] Figure 6 are P-V curve diagrams of example 1, comparative examples 2-4 under different oxygen partial pressures in an HZO thin film step. DETAILED DESCRIPTION

[0046] With the development of technology, in the field of ferroelectric thin film technology preparation, it has gradually become a trend to research, prepare and use ferroelectric thin films with better ferroelectricity. In this background, the applicant found that hafnium oxide (HfO2) based ferroelectric thin films have ferroelectricity. Therefore, the applicant tried to research a hafnium oxide-based ferroelectric thin film with excellent ferroelectricity. First, the applicant tried to use a substrate, a bottom electrode, an HZO thin film and a top electrode as raw materials to make a hafnium oxide-based ferroelectric thin film. However, during the performance detection process of the hafnium oxide-based ferroelectric thin film, it was found that the hafnium oxide-based ferroelectric thin film had a leakage current phenomenon. Therefore, the applicant added a cover layer (Al2O3 thin film) between the HZO thin film and the top electrode. It was found through experiments that when the HZO thin film was deposited between the bottom electrode and the cover layer by pulse laser deposition, the hafnium oxide-based ferroelectric thin film had better ferroelectricity. In order to further improve the ferroelectricity, the applicant tried to add oxygen in the annealing step. It was found that when the oxygen was higher, the hafnium oxide-based ferroelectric thin film had good ferroelectricity. On this basis, the applicant continued to try a large number of experiments. The results showed that only when different oxygen was introduced in the pulse laser deposition step and the annealing, the hafnium oxide-based ferroelectric thin film had better ferroelectricity. Whether the gas was added in the process of magnetron sputtering had little effect on the results. The present application is based on the above findings.

[0047] In order to make the technical scheme of the present application more convenient to understand, the present application will be further described in detail in combination with tables and examples, but not as a limitation of the protection scope of the present application.

[0048] Device source:

[0049] Magnetron sputtering coating instrument: manufacturer: Dalian Qivi Science and Technology Development Co., Ltd., model CHI-AVC;

[0050] Pulsed laser deposition system: manufacturer: Japan Pascal Company;

[0051] Molecular pump: manufacturer: Agilent Technology Co., Ltd., model: TwisTorr 84 FS. Embodiment

[0052] Embodiment 1

[0053] Substrate pretreatment: take a 4-inch p-type silicon (Si) wafer, sequentially use acetone, ethanol and deionized water to ultrasonic clean the p-Si wafer, set the cleaning time to 5 min, after cleaning, use nitrogen gun to dry the surface of the cleaned silicon wafer, ready for use for the subsequent deposition of the bottom electrode TiN.

[0054] Deposition of TiN electrode: in the magnetron sputtering coating instrument, take TiN target material as raw material, after the cavity gas pressure in the magnetron sputtering coating instrument is extracted to 10-5Pa, heat the cavity to 350℃. Open the air valve, introduce 0.3Pa of nitrogen and argon mixed gas, control the gas flow ratio of nitrogen and argon to be 35:4, set the sputtering power to 200W, the sputtering time is 2h, then close the air valve, open the baffle to sputter TiN target into Ti ions, Ti ions react with N ions under high energy to generate TiN and deposit on the P-type silicon wafer substrate, and the thickness of the obtained TiN electrode is 120nm. Cut the p-type silicon wafer with deposited TiN electrode into 10x10mm specifications for the next step of HZO film deposition.

[0055] Deposition of HZO film: use the pulsed laser deposition system, extract the deposition cavity gas pressure to 10-6Pa, heat the p-Si wafer to 450℃, close the valve of the molecular pump, introduce oxygen, adjust the oxygen partial pressure of the cavity to 20mTorr; use the baffle to block the heating p-Si wafer, open the laser, adjust the laser energy to 1.5W, the laser power is 2W, the laser frequency is 9.9Hz, the aperture size is 0.5, the aperture distance is-30cm, and the target distance is 5cm. Place the HZO ceramic target on the cut TiN electrode, use the laser to ablate the HZO ceramic target to form a plasma plume, further adjust the oxygen partial pressure to 20mTorr after stabilization, remove the baffle to start depositing HZO film. The laser energy for depositing HZO film is 1.5W, the laser frequency is 9.9Hz, and the laser frequency is 2000. After depositing the HZO film, heat for 60s, and a HZO film with a thickness of 4.3nm is obtained.

[0056] Deposition of Al2O3 film: heat the p-Si wafer to 450℃, adjust the oxygen partial pressure in the cavity of the pulsed laser deposition system to 80 mTorr; use a baffle to block the p-Si wafer, turn on the laser, adjust the laser energy to 2 W, the laser power is 2 W, the laser frequency is 9.9 Hz, the aperture size is 0.5, the aperture distance is -30 cm, and the target distance is 5 cm. Place the amorphous Al2O3 ceramic target on the HZO film, use laser ablation of the Al2O3 ceramic target to form a plasma plume, further adjust the oxygen partial pressure in the cavity to 80 mTorr and keep it stable during the process, and when the plasma plume is completely formed, remove the baffle and start depositing the Al2O3 film with the pulsed laser deposition device; set the laser energy for depositing the Al2O3 film to 2 W, the laser frequency to 9.9 Hz, and the laser shot number to 12000, and after depositing the HZO film, keep it for 600 s, and then an Al2O3 film with a thickness of 20 nm is obtained. At this time, the substrate, TiN bottom electrode, HZO film, and Al2O3 film are arranged in sequence to form a thin film sample.

[0057] Annealing: anneal the deposited thin film sample in the cavity, set the annealing temperature to 500℃, the annealing time to 3 min, and the annealing atmosphere to 80 mTorr oxygen partial pressure.

[0058] Deposition of Au electrode: after the annealing is completed, use a magnetron sputtering film coater to magnetron sputter Au electrode on the thin film sample. First, the cavity gas pressure in the magnetron sputtering film coater is pumped to 3×10 -3 Pa, open the air valve to introduce argon, set the sputtering power to 40 W, and the sputtering time to 300 s, then sputter the Au target at room temperature, cover the prepared Al2O3 film with a mask, and sputter a circular Au electrode with a diameter of 500 um. At this time, the p-Si wafer, TiN electrode, HZO film, Al2O3 film, and Au electrode are arranged in sequence to form the final hafnium oxide-based ferroelectric thin film.

[0059] Example 2

[0060] The difference between this example and Example 1 is that the deposition of the HZO film: the laser shot number is 4000, and after deposition, a 6.3 nm HZO film is obtained. The deposition of the Al2O3 film: the laser shot number is 18000, and after deposition, a 30 nm Al2O3 film is obtained.

[0061] Example 3

[0062] The difference between this example and Example 1 is that the deposition of the HZO film: the laser shot number is 6000, and after deposition, a 10 nm HZO film is obtained. The deposition of the Al2O3 film: the laser shot number is 6000, and after deposition, a 10 nm Al2O3 film is obtained.

[0063] Example 4

[0064] The difference between this example and Example 1 is that the deposition of the HZO film: the p-Si wafer is heated to 480°C, and after the deposition, a 4.3 nm HZO film is obtained. The deposition of the Al2O3 film: the p-Si wafer is heated to 480°C, and after the deposition, a 20 nm Al2O3 film is obtained.

[0065] Example 5

[0066] The difference between this example and Example 1 is that the deposition of the HZO film: the p-Si wafer is heated to 480°C, and after the deposition, a 6.3 nm HZO film is obtained. The deposition of the Al2O3 film: the p-Si wafer is heated to 480°C, and after the deposition, a 30 nm Al2O3 film is obtained.

[0067] Example 6

[0068] The difference between this example and Example 1 is that the deposition of the HZO film: the p-Si wafer is heated to 480°C, and after the deposition, a 10 nm HZO film is obtained. The deposition of the Al2O3 film: the p-Si wafer is heated to 480°C, and after the deposition, a 10 nm Al2O3 film is obtained.

[0069] Example 7

[0070] The difference between this example and Example 1 is that the deposition of the HZO film: the p-Si wafer is heated to 500°C, and after the deposition, a 4.3 nm HZO film is obtained. The deposition of the Al2O3 film: the p-Si wafer is heated to 500°C, and after the deposition, a 20 nm Al2O3 film is obtained.

[0071] Example 8

[0072] The difference between this example and Example 1 is that the deposition of the HZO film: the p-Si wafer is heated to 500°C, and after the deposition, a 6.3 nm HZO film is obtained. The deposition of the Al2O3 film: the p-Si wafer is heated to 500°C, and after the deposition, a 30 nm Al2O3 film is obtained.

[0073] Example 9

[0074] The difference between this example and Example 1 is that the deposition of the HZO film: the p-Si wafer is heated to 500°C, and after the deposition, a 10 nm HZO film is obtained. The deposition of the Al2O3 film: the p-Si wafer is heated to 500°C, and after the deposition, a 10 nm Al2O3 film is obtained.

[0075] Example 10

[0076] The difference between this example and Example 1 is that the annealing temperature is 450℃, the annealing time is 10 min, and the annealing atmosphere is 20 mTorr oxygen partial pressure.

[0077] Comparative Example

[0078] Comparative Example 1

[0079] The difference between this example and Example 1 is that the annealing temperature is 480℃, the annealing time is 8 min, and the annealing atmosphere is 10 mTorr oxygen partial pressure.

[0080] Comparative Example 2

[0081] The difference between this example and Example 1 is that the deposition of HZO film: the p-Si wafer is heated to 450℃, and after deposition, a 4.3 nm HZO film is obtained, and the oxygen partial pressure is changed to 50 mTorr. The step of depositing the Al2O3 film is not performed.

[0082] Comparative Example 3

[0083] The difference between this example and Example 1 is that the deposition of HZO film: the p-Si wafer is heated to 450℃, and after deposition, a 4.3 nm HZO film is obtained, and the oxygen partial pressure is changed to 80 mTorr. The step of depositing the Al2O3 film is not performed.

[0084] Comparative Example 4

[0085] The difference between this example and Example 1 is that the deposition of HZO film: the p-Si wafer is heated to 450℃, and after deposition, a 4.3 nm HZO film is obtained, and the oxygen partial pressure is changed to 100 mTorr. The step of depositing the Al2O3 film is not performed.

[0086] Data Analysis

[0087] Combination Figure 5 , Example 1, Example 10, and Comparative Example 1, the annealing atmosphere in Example 1 is 80 mTorr oxygen partial pressure, the annealing atmosphere in Example 10 is 20 mTorr oxygen partial pressure, and the annealing atmosphere in Comparative Example 1 is 10 mTorr oxygen partial pressure, and accordingly, in Figure 5 , the remanent polarization (Pr) value of Example 1 is 2, the Pr value of Example 10 is 0.3, and the Pr value of Comparative Example 1 is 0.2; as known, the better the Pr value, the better the ferroelectricity, and the annealing oxygen partial pressure of Example 1 is the highest, and the ferroelectricity is the best, which can be applied to the manufacture of negative capacitance field effect transistors with high requirements for ferroelectricity.

[0088] From Figure 3 , it can be seen that when the step of depositing the Al2O3 film is added in the hafnium oxide-based ferroelectric film, the leakage current is 1X10-6 A, and at this voltage, the leakage current of the step of depositing without adding the Al2O3 film is 1 X 10 -3 A. Moreover, when the voltage is outside the range of 0-1 V, the leakage current of the step of depositing with the addition of the Al2O3 film is much smaller than that of the step of depositing without the addition of the Al2O3 film.

[0089] In combination Figure 4 , Examples 1-3, when the number of excitations of the steps of depositing the HZO film and depositing the Al2O3 film is changed, the thickness of the formed film can be correspondingly controlled, when the thickness of the film is between 4.3-10.0 nm, the linearity of the hafnium oxide-based ferroelectric film is poor, and the ferroelectric performance is better. Meanwhile, the number of excitations of Example 1 is 2000, at this time, the residual polarization (Pr) value in S1 is 2, reaching the highest, the Pr values of Examples 2 and 3 are only close to 0.5, and thus the ferroelectricity of Example 1 is optimal.

[0090] In combination Figure 4 , Examples 1, 4-10, when the temperature of the steps of depositing the HZO film and depositing the Al2O3 film is changed, the thickness of the formed film can be correspondingly controlled, when the temperature of the film is between 450-500°C, the thickness of the film is controlled to be between 10-30 nm, at this time, the linearity of the hafnium oxide-based ferroelectric film is poor, and the ferroelectric performance is better. Further, the temperature of Example 1 is 450°C, and the temperatures of Examples 4-10 are all higher than 450°C, correspondingly, the Pr value of S1 is 2, and the Pr values of Examples 4-10 are all less than 2, and thus the ferroelectricity of Example 1 is optimal.

[0091] In combination Figure 6 , Examples 1, Comparative Examples 2-4, Example 1 adds the step of depositing the Al2O3 film, and the oxygen partial pressure in the step of depositing the HZO film is 20 mTorr, Comparative Examples 2-4 all do not add the step of depositing the Al2O3 film, and the oxygen partial pressures in the step of depositing the HZO film are 50 mTorr, 80 mTorr and 100 mTorr respectively, and correspondingly, in Figure 6 , the corresponding graph of Example 1 is denser, and the corresponding graph of Comparative Example 4 is sparser, when the oxygen partial pressure is 20 mTorr, the P-V curve is denser, indicating that the test can withstand a higher breakdown voltage, and when the oxygen partial pressure is 100 mTorr, the test is broken down at more than 4 V; meanwhile, when the oxygen partial pressure is 80 mTorr and 100 mTorr, the line in the graph is close to a straight line, indicating that the linearity is poor, and thus the ferroelectricity is also poor.

[0092] In summary, when the raw material of the hafnium oxide ferroelectric film includes the substrate, the bottom electrode, the HZO film, the cover layer and the top electrode, the hafnium oxide ferroelectric film has good ferroelectricity, can resist higher breakdown voltage, and can also inhibit the leakage current; when the oxygen partial pressure of the annealing is higher, especially reaches 80 mTorr, the ferroelectricity of the hafnium oxide ferroelectric film can be further enhanced; more, when the excitation number is lower, the temperature is lower and the oxygen partial pressure is lower in the deposition of the HZO film and the deposition of the Al2O3 film, the hafnium oxide ferroelectric film prepared has the strongest ferroelectricity, and can be applied to the manufacture of negative capacitance field effect transistors.

[0093] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application, and those skilled in the art can make modifications to the embodiments without creative contribution according to the needs after reading the present specification, but as long as the modifications are within the scope of the claims of the present application, are protected by the patent law.

Claims

1. A method for preparing a hafnium oxide-based ferroelectric thin film, characterized in that: The steps include: Substrate pretreatment: Take a 4-inch p-type silicon (Si) wafer and ultrasonically clean it with acetone, ethanol, and deionized water in sequence for 5 minutes. After cleaning, use a nitrogen gun to blow dry the cleaned silicon wafer surface to prepare for the subsequent deposition of TiN bottom electrode. Deposition of TiN electrode: In the magnetron sputtering coating instrument, TiN target material is used as raw material, and the chamber pressure in the magnetron sputtering coating instrument is pumped to 10 -5 Pa, heating the chamber to 350 ° C; opening the vent valve, introducing a mixture of nitrogen and argon at 0.3 Pa, controlling the gas flow ratio of nitrogen and argon to 35:4, setting the sputtering power to 200 W, and the sputtering time to 2 hours, then closing the vent valve, opening the baffle to sputter the TiN target into Ti ions, and the Ti ions and N ions react under high energy to form TiN and deposit on the P-type silicon wafer substrate, so that the thickness of the obtained TiN electrode is 120 nm; cutting the p-type silicon wafer with the TiN electrode deposited into 10×10 mm specifications for the next step of HZO thin film deposition; Deposition of HZO thin film: Using a pulsed laser deposition system, the pressure in the deposition chamber was pumped down to 10 -6 Pa, heat the p-Si wafer to 450℃, close the valve of the molecular pump, introduce oxygen, and adjust the oxygen partial pressure in the cavity to 20mTorr; use a baffle to block the heated p-Si wafer, turn on the laser, adjust the laser energy to 1.5W, the laser power to 2W, the laser frequency to 9.9Hz, the aperture size to 0.5, the aperture distance to 30cm, and the target distance to 5cm; place the HZO ceramic target on the cut TiN electrode, and use the laser to ablate the HZO ceramic target to form a plasma plume. During this process, further adjust the oxygen partial pressure to 20mTorr and stabilize it, then remove the baffle and start depositing the HZO film; the laser energy for depositing the HZO film is 1.5W, the laser frequency is 9.9Hz, and the number of laser shots is 2000; after the HZO film is deposited, keep warm for 60s to obtain a HZO film with a thickness of 4.3nm; Deposition of Al2O3 thin films: Heat the p-Si wafer to 450°C and adjust the chamber oxygen partial pressure in the pulsed laser deposition system to 80 mTorr; A baffle was used to block the p-Si wafer, and the laser was turned on. The laser energy was adjusted to 2W, the laser power was 2W, the laser frequency was 9.9Hz, the aperture size was 0.5, the aperture distance was 30cm, and the target distance was 5cm. An amorphous Al2O3 ceramic target was placed on the HZO film, and the Al2O3 ceramic target was ablated by laser to form a plasma plume. During this process, the oxygen partial pressure in the cavity was further adjusted to 80mTorr and kept stable. When the plasma plume was fully formed, the baffle was removed and the Al2O3 film was deposited using a pulsed laser deposition device. The laser energy for depositing the Al2O3 film was set to 2W, the laser frequency was 9.9Hz, and the number of laser shots was 12,000. After the HZO film was deposited, the heat was maintained for 600s to obtain an Al2O3 film with a thickness of 20nm. At this point, the substrate, TiN bottom electrode, HZO film, and Al2O3 film were arranged in sequence to form a thin film sample. Annealing: The deposited thin film sample was annealed in a chamber at a temperature of 500°C, a time of 3 minutes, and an oxygen partial pressure of 80 mTorr. Deposition of Au electrode: After annealing, the thin film sample was magnetron sputtered with Au electrode using a magnetron sputtering coater. First, the chamber pressure in the magnetron sputtering coater was pumped down to 3×10 -3 Pa, open the vent valve to let in argon, set the sputtering power to 40W, the sputtering time to 300s, then sputter the Au target at room temperature, cover the Al2O3 film prepared above with a mask, and plate a circular Au electrode with an electrode diameter of 500um. At this time, the p-Si sheet, TiN electrode, HZO film, Al2O3 film and Au electrode are arranged in sequence to form the final hafnium oxide-based ferroelectric film.

2. A hafnium oxide ferroelectric thin film, characterized in that: The hafnium oxide ferroelectric thin film is prepared by the preparation method of the hafnium oxide ferroelectric thin film according to claim 1.

3. A use of the hafnium oxide ferroelectric thin film according to claim 2, characterized in that: The hafnium oxide ferroelectric thin film is used for manufacturing negative capacitance field effect transistors.

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