CN114400179A - Hafnium oxide-based ferroelectric film, preparation method and application - Google Patents

Abstract

The application relates to the technical field of ferroelectric film preparation, and particularly discloses a hafnium oxide based ferroelectric film, a preparation method and application thereof. The preparation method of the hafnium oxide based ferroelectric film comprises the following steps: substrate pretreatment: cleaning the substrate by using an organic solvent; deposition of bottom electrode: depositing a bottom electrode on a substrate by adopting a physical vapor deposition mode; deposition of HZO thin film: depositing an HZO thin film on the bottom electrode in a pulsed laser deposition mode; and (3) deposition of a covering layer: depositing a covering layer on the HZO film by adopting a pulsed laser deposition mode; annealing: introducing 20-80mTorr oxygen at the temperature of 400-; top electrode deposition: and depositing a top electrode on the covering layer by adopting a physical vapor deposition mode to form the hafnium oxide-based ferroelectric film. The hafnium oxide-based ferroelectric film can be used for manufacturing a negative capacitance field effect transistor and has the characteristic of excellent ferroelectric property.

Description

A hafnium oxide-based ferroelectric thin film, preparation method and application

technical field

The present application relates to the field of technical preparation of ferroelectric thin films, and more particularly, to a hafnium oxide-based ferroelectric thin film, a preparation method and applications.

Background technique

Ferroelectricity means that a material has two or more spontaneous polarization states, and the spontaneous polarization can be reversed under the action of an external electric field. When the external electric field is removed, the spontaneous polarization still exists; Ferroelectricity can be widely used in non-volatile storage media, such as ferroelectric memories, ferroelectric field effect transistors, ferroelectric tunneling junctions, and the like.

With the rapid development of social media and mobile device technology, electronic components follow the development law of "Moore's Law", and are developing rapidly in the direction of size miniaturization and integration, and ferroelectric thin films are also evolving towards miniature size.

At present, the most widely used ferroelectric thin film materials are perovskite-based ferroelectric thin films, such as lead zirconate titanate, barium titanate, strontium bismuth tantalate, etc. Although they have the advantage of high remanent polarization, they also exist There are disadvantages, such as Pb polluting the environment, facing the disappearance of ferroelectricity at the nanoscale and unable to miniaturize, poor resistance to hydrogenation and other complex environments, incompatibility with CMOS processes, etc. Therefore, it is urgent to develop environmentally friendly, high-performance, A new type of ferroelectric thin film material with small thickness and compatible with existing processes to replace traditional perovskite-based materials.

Hafnium oxide-based ferroelectric thin films not only solve the problems in the above technologies, but also have good electrical properties and thermal stability in nanometer size, and are considered to be an ideal insulating gate material, but hafnium oxide-based ferroelectric thin films There is a defect of poor ferroelectric performance.

SUMMARY OF THE INVENTION

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

In the first aspect, the preparation method of a hafnium oxide-based ferroelectric thin film provided by the application comprises the following steps:

Substrate pretreatment: use organic solvent to clean the substrate;

Bottom electrode deposition: the bottom electrode is deposited on the substrate by physical vapor deposition;

Deposition of HZO film: The HZO film is deposited on the bottom electrode by pulsed laser deposition, the deposition temperature is set to 400-550°C, and the number of excitation lights is 2000-6500, so that the thickness of the formed HZO film is 4-20nm;

Overlay deposition: The overcoat layer is deposited on the HZO thin film by pulsed laser deposition, the deposition temperature is set to 400-500°C, and the number of excitation lights is set to 6000-20000 rounds, so that the thickness of the formed overlying layer is 8-30nm. film samples;

Annealing: Pour 20-80mTorr of oxygen at a high temperature of 400-800℃, keep the film sample for 3-30min, and then cool the film sample to room temperature;

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

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, and the thermal expansion coefficient of the bottom electrode is used to provide strain to control the ferroelectricity of the HZO film, and the cover layer provides clamping stress. , to improve the ferroelectricity and reliability of the HZO film; at the same time, during the annealing process, an oxygen pressure of 20-80 mTorr was used, under this oxygen pressure range, the ferroelectricity of the ferroelectric film can be further enhanced.

Optionally, 10-100 mTorr oxygen gas is introduced during the pulsed laser deposition process for forming the HZO film, and 80-200 mTorr oxygen gas is introduced during the pulsed laser deposition process for forming the cover layer.

By adopting the above technical scheme, oxygen is introduced into the HZO film and the cover layer, and oxygen vacancies are formed by introducing different contents of oxygen during the deposition process, which can better enhance the ferroelectricity of the ferroelectric film.

Optionally, the pulsed laser deposition temperature of the HZO film is set to 450-500° C., and the number of excitation lights is set to 2000-6000 rounds, so that the thickness of the prepared HZO film is 4-10 nm; the pulsed laser deposition of the cover layer is performed. The temperature was set at 450-500°C, and the excitation light number was set at 6000-18000 rounds, so that the thickness of the prepared coating layer was 10-30 nm.

By adopting the above technical scheme, the thickness of the HZO film and the cover layer can be further adjusted by adjusting the excitation number during the pulsed laser deposition process, and by changing the temperature during the pulsed laser deposition process, to understand the effect of temperature on the crystallization of the HZO film and the cover layer. Through experiments, it was found that the crystalline properties of the HZO film and the capping layer were better when the temperature was lower.

Optionally, the pulsed laser power of the HZO film and the cover layer are both 1.5-2W, the laser frequency is both 5-9.9Hz, the aperture size is both 0.5, the aperture distance is -30cm, and the target distance is both 3-5cm .

By adopting the above technical solution, the size of the plume formed by laser ablation of the target material can be adjusted in the laser parameters, thereby controlling the growth of the HZO thin film and the cover layer.

Optionally, the bottom electrode is a TiN electrode.

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

By adopting the above technical solution, the magnetron sputtering can realize the deposition of a large area, so it can ensure the consistency of the composition and structure of the film of the bottom electrode or the top electrode.

Optionally, the cover layer is an Al ₂ O ₃ thin film.

Optionally, the thickness of the Al ₂ O ₃ thin film is 20-30 nm.

Preferably, the deposition state of the Al ₂ O ₃ thin film is amorphous.

By adopting the above technical solution, since the Al ₂ O ₃ film is deposited on the HZO film, when the thickness of the Al ₂ O ₃ film is lower than 20 nm or higher than ₃₀ nm, the ferroelectricity of the HZO film will be reduced _; In addition to being a cover layer, the thin film can also be used as an insulating layer, especially when the deposition state is amorphous, the leakage current of the thin film structure can be suppressed, and the ferroelectricity of the HZO thin film can be further improved.

Optionally, the thickness of the HZO film is 4.3-10 nm.

By adopting the above technical solution, when the thickness is less than 4nm, the ferroelectricity of the finally formed hafnium oxide-based ferroelectric thin film will deteriorate; when the thickness is higher than 10nm, it is not conducive to the integration of CMOS process, and cannot reflect the hafnium oxide-based ferroelectric film. Ferroelectric films are thin and have the advantage of being ferroelectric.

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

By adopting the above technical solution, the silicon wafer can be better compatible with the CMOS process, and the p-type silicon wafer has a specific crystal plane, which can provide corresponding lattice mismatch stress, thereby affecting the growth of the thin film.

Optionally, the top electrode is an Au electrode.

In a second aspect, the present application provides a hafnium oxide-based ferroelectric thin film prepared by a method for preparing a hafnium oxide-based ferroelectric thin film.

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

In a third aspect, the present application provides an application of a hafnium oxide ferroelectric thin film, which is mainly used in the fabrication of negative capacitance field effect transistors.

To sum up, the present application includes at least one of the following beneficial technical effects:

1. The method of the present application adopts the HZO film, which has good ferroelectricity, and the HZO film is deposited between the bottom electrode and the cover layer, and the HZO film is induced to form ferroelectricity by using a suitable thermal expansion coefficient and clamping stress, Furthermore, it has stronger ferroelectricity; at the same time, 20-80mTorr oxygen is added in the annealing step to further enhance the ferroelectricity of the hafnium oxide-based ferroelectric thin film. It has been verified that when the oxygen pressure is 80mTorr, its Pr value is 2, Ferroelectricity is the best;

2. In this application, oxygen is added in the pulsed laser deposition. Specifically, 10-100 mTorr oxygen is added in the deposition step of the HZO film, and 80-200 mTorr oxygen is added in the deposition step of the Al ₂ O ₃ film, combined with the annealing step. 20-80mTorr oxygen, when oxygen is used in each step, oxygen vacancies are formed, and the formation of oxygen vacancies is beneficial to enhance the ferroelectricity of hafnium oxide-based ferroelectric thin films;

3. In this application, the excitation number or temperature is controlled in the deposition process of the HZO film or the deposition process of the Al ₂ O ₃ film, and then the thickness of the HZO film and the Al ₂ O ₃ film is controlled. The results show that: when the excitation number used in the deposition of HZO film is smaller, the thickness of the formed HZO film is also smaller, and the final hafnium oxide _- based ferroelectric film has better ferroelectricity. ₃ When the temperature used in the film deposition process is between 450-500 °C, and the thickness of the formed Al ₂ O ₃ film is controlled to be 10-30 nm, the final hafnium oxide-based ferroelectric thin film has better ferroelectricity and can be It is used to make negative capacitance field effect transistors.

Description of drawings

Fig. 1 is the flow chart of preparing hafnium oxide-based ferroelectric thin film provided by the application;

Fig. 2 is the atomic force microscope and piezoelectric force microscope images of the hafnium oxide-based ferroelectric thin film and the corresponding phase and amplitude diagrams;

Fig. 3 is a graph comparing the leakage current curves of the hafnium oxide-based ferroelectric thin film in the deposition step with the Al ₂ O ₃ thin film added and the deposition step without the Al ₂ O ₃ thin film;

5 is a P-V curve diagram of Example 1 to Example 9 of the hafnium oxide-based ferroelectric thin film;

4 is a P-V curve diagram of Example 1, Example 10 and Comparative Example 1 of the hafnium oxide-based ferroelectric thin film;

6 is a P-V curve diagram of different oxygen partial pressures in Example 1, Comparative Example 2-Comparative Example 4 under the HZO thin film step.

Detailed ways

With the development of technology, in the field of ferroelectric thin film technology preparation, research, preparation and utilization of ferroelectric thin films with better _{ferroelectricity} have gradually become a trend. The ferroelectric film has ferroelectricity. Therefore, the applicant tried to develop a hafnium oxide-based ferroelectric film with excellent ferroelectricity. First, the applicant tried to select the substrate, the bottom electrode, the HZO film and the top electrode as raw materials. , make the hafnium oxide-based ferroelectric thin film, but in the process of carrying out performance detection to the obtained hafnium oxide-based ferroelectric thin film, it is found that the hafnium oxide-based ferroelectric thin film has the phenomenon of leakage current, so the applicant is in the HZO thin film. A cover layer (Al ₂ O ₃ film) was added between the bottom electrode and the top electrode. It was found that the hafnium oxide-based ferroelectric film was prepared by using pulsed laser deposition and depositing a HZO film between the bottom electrode and the cover layer. It has good 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 high, the ferroelectricity of the hafnium oxide-based ferroelectric thin film was very good. On this basis , the applicant continued to try to carry out a large number of experiments, using magnetron sputtering during the deposition of the bottom electrode and the top electrode, using pulse excitation deposition during film deposition, and feeding oxygen or argon or argon in each step. It was found that the hafnium oxide-based ferroelectric films had better ferroelectricity only when different oxygen was introduced during the pulsed laser deposition step and annealing. The results have little impact, and the present application is based on the above findings.

In order to make it easier to understand the technical solutions of the present application, the present application will be described in further detail below with reference to the tables and examples, but it is not regarded as the protection scope limited by the present application.

Equipment source:

Magnetron sputtering coater: Manufacturer: Dalian Qiwei Technology Development Co., Ltd., model CHI-AVC;

Pulsed laser deposition system: Manufacturer: Pascal, Japan;

Molecular Pump: Manufacturer: Agilent Technologies, Inc. Model: TwisTorr 84 FS.

Example

Example 1

Substrate pretreatment: Take a 4-inch p-type silicon (Si) wafer, and then use acetone, ethanol and deionized water to ultrasonically clean the p-Si wafer, set the cleaning time to 5min, and blow it with a nitrogen gun after cleaning. The surface of the silicon wafer after dry cleaning is used for subsequent deposition of the bottom electrode TiN.

Deposition of TiN electrode: In the magnetron sputtering coater, the TiN target is used as the raw material, the chamber pressure in the magnetron sputtering coater is pumped to 10-5Pa, and the chamber is heated to 350°C. Open the ventilation valve, introduce a mixture of nitrogen and argon gas at 0.3Pa, control the ratio of nitrogen and argon gas flow to 35:4, set the sputtering power to 200W, and set the sputtering time to 2h, then close the ventilation valve and open the shutter. Plate sputtering TiN target to form Ti ions, Ti ions react with N ions under the action of high energy to form TiN and deposit on the P-type silicon substrate. The thickness of the obtained TiN electrode is 120nm. The p-type silicon wafer on which the TiN electrode is deposited is cut into a size of 10 × 10 mm for the next step of HZO thin film deposition.

Deposition of HZO thin films: Using a pulsed laser deposition system, the pressure of the deposition chamber was pumped to 10-6Pa, the p-Si wafer was heated to 450°C, the valve of the molecular pump was closed, oxygen was introduced, and the oxygen partial pressure of the chamber was adjusted to 20mTorr ; Use a baffle to block the heated p-Si sheet, 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. A HZO ceramic target was placed on the cut TiN electrode, and a laser was used to ablate the HZO ceramic target to form a plasma plume. During this process, the oxygen partial pressure was further adjusted to 20mTorr and stabilized, and the baffle was removed to start the deposition of 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 depositing the HZO film, the HZO film with a thickness of 4.3 nm was obtained by holding the temperature for 60 s.

Deposition of Al ₂ O ₃ film: heat the p-Si sheet to 450°C, adjust the oxygen partial pressure in the pulsed laser deposition system to 80 mTorr; use a baffle to block the p-Si sheet, turn on the laser, and adjust the laser energy to 2W , 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. An amorphous Al ₂ O ₃ ceramic target is placed on the HZO film, and the Al ₂ O ₃ ceramic target is ablated by laser to form a plasma plume. In the process, the oxygen partial pressure in the cavity is further adjusted to 80mTorr and kept stable. When the plasma plume was completely formed, the baffle was removed and the Al _{2 O 3 film was deposited by pulsed laser deposition equipment; the laser energy for depositing the Al 2 O 3 film was} set to 2W, the laser frequency was 9.9 Hz, and the laser The number of rounds is 12000, and the Al ₂ O ₃ film with a thickness of 20 nm can be obtained after the HZO film is deposited and kept for 600 s. At this time, the substrate, the TiN bottom electrode, the HZO thin film, and the Al ₂ O ₃ thin film were sequentially arranged to form a thin film sample.

Annealing: The deposited film samples were annealed in the chamber, the annealing temperature was set at 500°C, the annealing time was 3min, and the annealing atmosphere was 80mTorr oxygen partial pressure.

Deposition of Au electrodes: After annealing, the film samples were magnetron sputtered with Au electrodes using a magnetron sputtering coater. First, the chamber pressure in the magnetron sputtering coater was pumped to 3×10 ^-3 Pa , open the ventilation valve and let in argon gas, set the sputtering power to 40W and the sputtering time to 300s, then sputter the Au target at room temperature, cover the above-prepared Al ₂ O ₃ film with a mask, and coat the A circular Au electrode with an electrode diameter of 500um, at this time, p-Si sheet, TiN electrode, HZO film, Al ₂ O ₃ film and Au electrode are arranged in sequence to form the final hafnium oxide-based ferroelectric film.

Example 2

The difference between this embodiment and Embodiment 1 is: the deposition of the HZO film: the number of laser shots is 4000, and the HZO film of 6.3 nm is obtained after the deposition. Deposition of Al ₂ O ₃ thin film: the number of laser shots is 18,000, and after deposition, Al ₂ O ₃ thin film of 30 nm is obtained.

Example 3

The difference between this embodiment and Embodiment 1 is: the deposition of the HZO film: the number of laser shots is 6000, and the HZO film of 10 nm is obtained after the deposition. Deposition of Al ₂ O ₃ thin film: The number of laser shots is 6000, and after the deposition, Al ₂ O ₃ thin film of 10 nm is obtained.

Example 4

The difference between this embodiment and Embodiment 1 is: the deposition of HZO thin film: heating the p-Si sheet to 480° C., and obtaining a 4.3 nm HZO thin film after the deposition. Deposition of Al ₂ O ₃ thin film: heating the p-Si sheet to 480° C., and obtaining a 20 nm Al ₂ O ₃ thin film after deposition.

Example 5

The difference between this embodiment and Embodiment 1 is: the deposition of HZO thin film: heating the p-Si sheet to 480° C., and obtaining a 6.3 nm HZO thin film after the deposition. Deposition of Al ₂ O ₃ thin film: heating the p-Si sheet to 480° C., and obtaining a 30 nm Al ₂ O ₃ thin film after deposition.

Example 6

The difference between this example and Example 1 is: deposition of HZO thin film: heating the p-Si sheet to 480° C., and obtaining a 10 nm HZO thin film after the deposition. Deposition of Al ₂ O ₃ thin film: heating the p-Si sheet to 480° C., and obtaining a 10 nm Al ₂ O ₃ thin film after the deposition.

Example 7

The difference between this embodiment and Embodiment 1 is: deposition of HZO film: heating the p-Si sheet to 500° C., and obtaining a 4.3 nm HZO film after deposition. Deposition of Al ₂ O ₃ thin film: heating the p-Si sheet to 500° C., and obtaining a 20 nm Al ₂ O ₃ thin film after the deposition.

Example 8

The difference between this embodiment and Embodiment 1 is: deposition of HZO thin film: heating the p-Si sheet to 500° C., and obtaining a 6.3 nm HZO thin film after the deposition. Deposition of Al ₂ O ₃ thin film: heating the p-Si sheet to 500° C., and obtaining a 30 nm Al ₂ O ₃ thin film after deposition.

Example 9

The difference between this example and Example 1 is: deposition of HZO thin film: heating the p-Si sheet to 500° C., and obtaining a 10 nm HZO thin film after the deposition. Deposition of Al ₂ O ₃ thin film: heating the p-Si sheet to 500° C., and obtaining a 10 nm Al ₂ O ₃ thin film after deposition.

Example 10

The difference between this embodiment and Embodiment 1 is that the annealing temperature is 450° C., the annealing time is 10 min, and the annealing atmosphere is an oxygen partial pressure of 20 mTorr.

Comparative ratio

Comparative Example 1

The difference between this embodiment and Embodiment 1 is that the annealing temperature is 480° C., the annealing time is 8 min, and the annealing atmosphere is an oxygen partial pressure of 10 mTorr.

Comparative Example 2

The difference between this example and Example 1 is: the deposition of the HZO film: heating the p-Si sheet to 450°C, after the deposition, a 4.3nm HZO film is obtained, and the oxygen partial pressure is changed to 50mTorr. The deposition of the Al ₂ O ₃ film was not performed.

Comparative Example 3

The difference between this example and Example 1 is: the deposition of the HZO film: heating the p-Si sheet to 450°C, after the deposition, a 4.3nm HZO film is obtained, and the oxygen partial pressure is changed to 80mTorr. The deposition of the Al ₂ O ₃ film was not performed.

Comparative Example 4

The difference between this example and Example 1 is: the deposition of HZO film: heating the p-Si sheet to 450°C, after the deposition, a 4.3nm HZO film is obtained, and the oxygen partial pressure is changed to 100mTorr. The deposition of the Al ₂ O ₃ film was not performed.

data analysis

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. Correspondingly, 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; it is well known that when the Pr value is better, the ferroelectricity The better, the annealed oxygen partial pressure of Example 1 is the highest, and the ferroelectricity is the best, which can be applied to the fabrication of negative capacitance field effect transistors with high ferroelectricity requirements.

As can be seen from Fig. 3, when the hafnium oxide-based ferroelectric film is added with the deposition of Al ₂ O ₃ film, the leakage current is 1X10 ^-6 A at a voltage of -3V, while at this voltage The leakage current under this step of deposition without adding Al ₂ O ₃ film is 1× ^{10 −3} A. Moreover, when the voltage is outside the value of 0-1V, the leakage current of the deposition step with the addition of Al ₂ O ₃ film is much smaller than that of the deposition without the addition of Al ₂ O ₃ film.

Referring to Fig. 4, Example 1-Example 3, when the excitation numbers of the two steps of HZO film deposition and Al ₂ O ₃ film deposition are changed, the thickness of the formed film can be controlled accordingly. When the thickness of the film is 4.3 Between -10.0 nm, the linearity of the hafnium oxide-based ferroelectric thin film is poor, on the contrary, the ferroelectric performance is better; at the same time, the excitation number of Example 1 is 2000, and the remanent polarization (Pr) value in S1 at this time The Pr value of Example 2 and Example 3 is only close to 0.5, and the ferroelectricity of Example 1 is the best.

4, Example 1, Example 4-Example 10, when changing the temperature of the two steps of HZO film deposition and Al ₂ O ₃ film deposition, the thickness of the formed film can be controlled accordingly. When the temperature is between 450-500 °C, the thickness of the film is controlled between 10-30 nm. At this time, the linearity of the hafnium oxide-based ferroelectric film is poor, and the ferroelectric performance is better; more, the temperature of Example 1 is 450℃, the temperature of Example 4-Example 10 all exceeded 450℃, correspondingly, the Pr value of S1 was 2, while the Pr value of Example 4-Example 10 were all less than 2, so the ferroelectricity of Example 1 was reach the optimum.

With reference to Figure 6, Example 1, Comparative Example 2-Comparative Example 4, Example 1 is added with the deposition of Al ₂ O ₃ film, the oxygen partial pressure in the deposition of HZO film is 20mTorr, and Comparative Example 2- 4 are not added with the Al ₂ O ₃ film deposition step, the oxygen partial pressure in the HZO film deposition step is 50 mTorr, 80 mTorr and 100 mTorr, correspondingly, in Figure 6, Example 1 corresponds to The graph is denser, and the graph corresponding to Comparative Example 4 is sparse. When the oxygen partial pressure is 20mTorr, the PV curve is denser, indicating that the test can withstand a higher breakdown voltage, while 100mTorr indicates that the test exceeds 4V. When the oxygen partial pressure is 80 mTorr and 100 mTorr, the line in the figure is close to a straight line, indicating that the linearity is poor, and the ferroelectricity is also poor.

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, it has good ferroelectricity, can withstand higher breakdown voltage, and can also suppress leakage current. ; When the oxygen partial pressure of annealing is higher, especially when it reaches 80 mTorr, the ferroelectricity of hafnium oxide ferroelectric films can be further enhanced; more, when the deposition of HZO films and the deposition of Al ₂ O ₃ films have higher excitation numbers When the temperature is low, the temperature is low and a low oxygen partial pressure is added, the prepared hafnium oxide ferroelectric thin film has the strongest ferroelectricity, and can be applied to the fabrication of negative capacitance field effect transistors.

This specific embodiment is only an explanation of the application, and it does not limit the application. Those skilled in the art can make modifications to the embodiment without creative contribution as needed after reading this specification, but as long as the rights of the application are All claims are protected by patent law.

Claims (10)

1. A preparation method of a hafnium oxide based ferroelectric film is characterized by comprising the following steps: substrate pretreatment: cleaning the substrate by using an organic solvent;

deposition of bottom electrode: depositing a bottom electrode on a substrate by adopting a physical vapor deposition mode;

deposition of HZO thin film: depositing the HZO film on the bottom electrode by adopting a pulsed laser deposition mode, setting the deposition temperature to be 400-;

and (3) deposition of a covering layer: depositing a covering layer on the HZO thin film by adopting a pulse laser deposition mode, setting the deposition temperature to be 400-;

annealing: introducing 20-80mTorr oxygen at the temperature of 400-;

top electrode deposition: and depositing a top electrode on the covering layer by adopting a physical vapor deposition mode to form the hafnium oxide-based ferroelectric film.

2. The method of claim 1, wherein the hafnium oxide-based ferroelectric thin film is prepared by: and introducing 10-100mTorr oxygen in the pulsed laser deposition process for forming the HZO thin film, and introducing 80-200mTorr oxygen in the pulsed laser deposition process for forming the covering layer.

3. The method of claim 1, wherein the hafnium oxide-based ferroelectric thin film is prepared by: the pulse laser deposition temperature of the HZO thin film is set to be 450-6000-, and the exciting light number is set to be 2000-6000-, so that the thickness of the prepared HZO thin film is 4-10 nm; the pulsed laser deposition temperature of the covering layer is set to be 450-500 ℃, the exciting light number is set to be 6000-18000, and the thickness of the prepared covering layer is 10-30 nm.

4. The method of claim 1, wherein the hafnium oxide-based ferroelectric thin film is prepared by: the bottom electrode is a TiN electrode.

5. The method of claim 1, wherein the hafnium oxide-based ferroelectric thin film is prepared by: the physical vapor deposition mode is magnetron sputtering; the magnetron sputtering power is 200-300W, and the sputtering time is 1-2 h.

6. The method of claim 1, wherein the hafnium oxide-based ferroelectric thin film is prepared by: the covering layer is Al₂O₃A film.

7. The method of claim 1, wherein the hafnium oxide-based ferroelectric thin film is prepared by: the thickness of the HZO thin film is 4.3-10 nm.

8. The method of claim 6, wherein the hafnium oxide-based ferroelectric thin film is prepared by: the Al is₂O₃The thickness of the film is 20-30 nm.

9. A hafnium oxide ferroelectric thin film, characterized in that: the hafnium ferroelectric thin film as claimed in any one of claims 1 to 8.

10. The use of the hafnium oxide ferroelectric thin film of claim 9, wherein: the hafnium oxide ferroelectric film is applied to manufacturing a negative capacitance field effect transistor.

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