Method for manufacturing dielectric thin film, dielectric thin film, and two-dimensional field effect transistor

Abstract

The application relates to the technical field of microelectronic processes. Specifically, the application relates to a dielectric film manufacturing method, a dielectric film and a two-dimensional field effect transistor. The dielectric film manufacturing method comprises the following steps: providing a growth substrate and dielectric film raw materials; atomically steping the substrate; annealing the growth substrate to form a step which is continuously extended along a crystal face direction and regularly arranged on the surface of the growth substrate, thereby forming a macroscopically flat atomically stepped surface structure; growing the dielectric film; covering the surface of the growth substrate with the dielectric film raw materials, and heating and oxidizing the growth substrate and the dielectric film raw materials under a reaction gas condition; and growing the dielectric film raw materials along the step in an ordered manner, finally connecting into a planar film structure and forming the dielectric film. The dielectric film manufacturing method disclosed by the application has small energy consumption, short reaction time and is suitable for large-scale preparation.

Description

Technical Field

[0001] This application relates to the field of microelectronics process technology. Specifically, it relates to a method for manufacturing dielectric thin films, as well as dielectric thin films and two-dimensional field-effect transistors. Background Technology

[0002] Two-dimensional (2D) materials, due to their atomic-level thickness, tunable band gap, high carrier mobility, and ease of integration with other materials, while retaining their original properties at the sub-nanometer scale, have become one of the most promising candidates in the post-Moore's Law era. 2D semiconductor materials, due to their unique physical and chemical properties, have gradually become a research hotspot. However, integrated circuits based on 2D semiconductors require ultra-thin gate insulators to provide high interface quality and dielectric reliability, reduce electroactive traps, and achieve efficient gate control. However, existing 2D insulators cannot provide a good balance in terms of band gap, breakdown strength, dielectric constant, and leakage current. To achieve efficient, low-power 2D electronic devices, the key lies in developing dielectric materials with high-k dielectric constants.

[0003] Traditional amorphous high-k gate dielectrics (such as HfO2, ZrO2, Al2O3, etc.) have been widely used in modern semiconductor manufacturing processes, but they suffer from serious problems such as charge scattering and trapped states in two-dimensional field-effect transistors (2D FETs). Recent research reports the exploration of novel two-dimensional high-k single crystals with atomically smooth surfaces as dielectrics. These high-k dielectrics can significantly improve interface quality and device performance, such as Gd2O5, Bi2SeO5, MgNb2O6, and Sr2Nb3O. 10 and CaCu3Ti4O 12 Materials such as calcium copper titanate and CCTO have all attracted widespread research attention due to their excellent dielectric properties. However, these novel high-k dielectrics still face significant challenges, including high energy consumption, long reaction times, easy surface contamination, and difficulties in large-scale fabrication.

[0004] Therefore, a solution is needed to address the problems of easy surface contamination, high energy consumption, long reaction time, and difficulty in large-scale preparation of high-k dielectric thin films. Summary of the Invention

[0005] Therefore, this application provides a method for manufacturing a dielectric thin film, as well as a dielectric thin film and a two-dimensional field-effect transistor, to solve the problems of easy surface contamination, high energy consumption, long reaction time, and difficulty in large-scale preparation of high-k dielectric thin films.

[0006] In one aspect of this application, a method for manufacturing a dielectric thin film is provided, comprising the following steps:

[0007] Provide growth substrates and dielectric film raw materials;

[0008] Atomic-level stepped substrate: The growth substrate is annealed to form several steps that extend continuously and are regularly arranged along the crystal plane on the surface of the growth substrate, forming a macroscopically flat atomic-level stepped surface structure.

[0009] Growth of dielectric films: The growth substrate and dielectric film raw materials are annealed and oxidized together under reactive gas conditions. The dielectric film raw materials grow in an orderly manner along the steps and finally connect into a planar film structure to form a dielectric film.

[0010] The dielectric thin film manufacturing method provided in this application involves first annealing the growth substrate to form several steps that extend continuously and are regularly arranged along the crystal planes on the substrate surface, constituting a macroscopically smooth atomic-level step surface structure. Due to its inherent properties, sapphire substrates naturally form such an atomic-level step surface structure after annealing. In the subsequent growth process, the dielectric thin film raw materials grow orderly along the steps, initially forming dispersed crystal domains, which, guided by the atomic-level step surface structure, form the same growth orientation. As growth progresses, they gradually merge into a single structure. Because the atomic-level step surface structure is macroscopically smooth, a smooth thin film can ultimately be formed. Furthermore, under these conditions, although Bi₂O₃ has multiple crystal forms, only body-centered cubic crystals can ultimately remain on the step surface for growth. Therefore, the final thin film contains only one crystal form, and due to the uniform orientation, the final thin film has no grain boundaries, resulting in high-quality film with a high dielectric constant. Other existing methods, such as ALD deposition, result in films with various crystal structures and different growth directions, leading to the presence of grain boundaries within the film and making it difficult to achieve the superior performance of the film produced by this method. Furthermore, the dielectric film formed in this way can be grown under ambient pressure, while other existing methods typically require higher temperatures (900°C) and lower pressures (such as vacuum), whereas this method eliminates these stringent conditions. Therefore, this method consumes less energy, has a shorter reaction time, and is suitable for large-scale fabrication.

[0011] In some embodiments of this application,

[0012] The growth substrate is a C-face sapphire substrate;

[0013] The dielectric film raw material is Bi powder;

[0014] The dielectric film is a γ-Bi2O3 film.

[0015] The dielectric thin film manufacturing method provided in this application exhibits excellent lattice constant compatibility between γ-Bi₂O₃ and the sapphire substrate, with a lattice mismatch value of only 5.2%. This ensures that after Bi powder is oxidized to γ-Bi₂O₃ during the reaction, it grows well along the extension direction of the steps on the sapphire substrate surface. Therefore, it can grow along the same orientation. Under these conditions, although Bi₂O₃ has multiple crystal forms, only body-centered cubic crystals can ultimately remain on the step surface for growth. Thus, the final thin film contains only one crystal form. Furthermore, due to the same orientation growth, the final thin film has no grain boundaries, resulting in high-quality film with a high dielectric constant. The final dielectric thin film exhibits excellent quality, with a maximum dielectric constant reaching 39.38, approaching 40. This is a significant improvement compared to the existing technologies where HfO₂ dielectric films only reach 20 and Ta₂O₅ dielectric films only reach 25.

[0016] In some embodiments of this application,

[0017] During the growth process, the dielectric thin film raw material forms an oxide thin film with a body-centered cubic crystal structure, and the corresponding crystals grow along the same orientation on different step surfaces.

[0018] The dielectric thin film manufacturing method provided in this application involves using dielectric thin film raw materials to form a body-centered cubic crystal structure during the dielectric thin film growth step. This crystal structure has only one crystal form and grows along the same orientation on the surfaces of different steps, resulting in a final thin film without grain boundaries. Therefore, the thin film has high quality and a high dielectric constant.

[0019] In some embodiments of this application,

[0020] During the atomic-level stepping process, the C-side sapphire substrate is annealed at 1400℃ for 4-6 hours.

[0021] The dielectric thin film manufacturing method provided in this application can form a well-morphological atomic-level step structure on the C-side sapphire substrate under annealing conditions at 1400℃ for 4-6 hours, which is beneficial for subsequent growth of the dielectric thin film. If the annealing time is less than 4 hours, it is difficult to form steps; if the annealing time is greater than 6 hours, it results in waste.

[0022] In some embodiments of this application,

[0023] During the growth of the dielectric film, the oxygen content in the reaction environment is less than or equal to 50 ppm.

[0024] The dielectric thin film manufacturing method provided in this application controls the oxygen content in the reaction environment to be less than or equal to 50 ppm. Therefore, it can be ensured that only a very small amount of Bi powder reacts to form Bi2O3 before reaching the set growth temperature. This Bi2O3 includes various other crystal forms, but is difficult to retain on the step surface. After reaching the growth temperature, the remaining Bi powder reacts with oxygen to mainly form body-centered cubic Bi2O3. Other crystal forms are extremely rare and difficult to retain, thus ensuring the uniqueness of the crystal form in the final thin film.

[0025] In some embodiments of this application,

[0026] The steps of growing a dielectric thin film include:

[0027] A container containing dielectric film raw materials is placed in the heating zone of the reaction apparatus. Simultaneously, a growth substrate forming atomic-level steps is placed downstream of the reaction apparatus, and an inert gas is introduced to purge the air from the reaction apparatus. Then, an argon-oxygen mixture is introduced into the reaction apparatus as a carrier gas, and the heating zone is raised to the reaction temperature. The reaction is continued for a period of time, allowing the dielectric film raw materials to grow orderly along the steps, eventually forming a planar thin film structure, thus creating a dielectric film.

[0028] In some embodiments of this application,

[0029] The amount of dielectric film raw material is 40mg to 60mg;

[0030] The argon-oxygen mixed gas was introduced at a rate of 250 sccm to 350 sccm.

[0031] The reaction temperature is 600℃~700℃; the reaction time is 30min~45min;

[0032] The heating rate to the reaction temperature is 20℃ / min to 30℃ / min.

[0033] If the above conditions are below the lower limit, it will be difficult to form a continuous thin film; if they exceed the upper limit, it will result in waste and cause accumulation at the crystal domain junctions, affecting the quality of the thin film.

[0034] In another aspect of this application, a dielectric film is also provided, manufactured using the dielectric film manufacturing method provided in this application;

[0035] in,

[0036] A dielectric thin film is a thin film with a monolithic structure formed by interconnected crystal domains; the crystal domains grow obliquely at a non-zero angle to the surface of the dielectric thin film.

[0037] The dielectric film provided in this application is manufactured using the dielectric film manufacturing method provided in this application. By first annealing the growth substrate, several steps extending continuously and regularly arranged along the crystal planes are formed on the surface of the growth substrate, constituting a macroscopically smooth atomic-level step surface structure. Due to its inherent properties, the sapphire substrate naturally forms such an atomic-level step surface structure after annealing. Thus, during the subsequent growth process, the dielectric film raw materials grow orderly along the steps, initially forming dispersed crystal domains, which are then guided by the steps to form the same growth orientation. As the growth time progresses, they gradually connect into a single entity. Because the atomic-level step surface structure is macroscopically smooth, a smooth film can ultimately be formed. Furthermore, under these conditions, although Bi₂O₃ has multiple crystal forms, only body-centered cubic crystals can ultimately remain on the step surface for growth. Therefore, the final film contains only one crystal form, and due to the uniform orientation, the final film has no grain boundaries, resulting in a high-quality film with a high dielectric constant. Other existing methods, such as ALD deposition, result in films with various crystal structures and different growth directions, leading to the presence of grain boundaries within the film and making it difficult to achieve the superior performance of the film produced by this method. Furthermore, the dielectric film formed in this way can be grown under ambient pressure, while other existing methods require higher temperatures (900°C) and lower pressures (such as vacuum), whereas this method eliminates these stringent conditions. Therefore, it consumes less energy, has a shorter reaction time, and is suitable for large-scale fabrication.

[0038] In some embodiments of this application,

[0039] A dielectric film is composed of oxide crystals of dielectric film raw materials with a body-centered cubic structure; the growth orientation of the oxide crystals of dielectric film raw materials is the same at any position in the dielectric film.

[0040] The dielectric film provided in this application is composed of oxide crystals of dielectric film raw materials with a body-centered cubic structure. Furthermore, the growth orientation of the oxide crystals of the dielectric film raw materials is the same at any location on the dielectric film, and only one crystal form, body-centered cubic, exists. Therefore, there are no grain boundaries within the film. Consequently, the film has high quality and a high dielectric constant.

[0041] In another aspect of this application, a two-dimensional field-effect transistor is also provided, comprising the dielectric thin film provided in this application.

[0042] The two-dimensional field-effect transistor provided in this application uses the dielectric thin film provided in this application. The dielectric thin film preparation process has low energy consumption and short reaction time, making it suitable for large-scale preparation. Moreover, the thin film has good quality and high dielectric constant. Therefore, the two-dimensional field-effect transistor based on this dielectric thin film can achieve a subthreshold swing of 80mV / dec, which is close to the thermodynamic limit. Compared with devices using traditional high-k dielectrics, it exhibits higher performance. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0044] Figure 1 This is a schematic flowchart of the dielectric thin film manufacturing method of this application;

[0045] Figure 2 An atomic force microscope image of the surface of a substrate after atomic stepping, in a dielectric thin film manufacturing method according to an embodiment of this application;

[0046] Figure 3 An atomic force microscope image of a dielectric thin film grown along the same orientation on a step surface in a dielectric thin film manufacturing method according to an embodiment of this application.

[0047] Figure 4a An optical microscope image of the dielectric film manufacturing method according to an embodiment of this application, showing the reaction of the dielectric film during the growth process after 20 minutes.

[0048] Figure 4b An optical microscope image of the dielectric film reaction after 40 minutes during the growth process of a dielectric film manufacturing method according to an embodiment of this application.

[0049] Figure 4c An optical microscope image of the dielectric film after 45 minutes of reaction during the growth process of the dielectric film in an embodiment of this application.

[0050] Figure 5a This is a partial transmission electron microscope image of the process of two adjacent crystal domains joining together in a dielectric thin film manufacturing method according to an embodiment of this application.

[0051] Figure 5b for Figure 5a Transmission electron microscope image magnified by rotation at the dashed box in the middle;

[0052] Figure 5c for Figure 5b Transmission electron microscope image magnified by rotation at the dashed box in the middle;

[0053] Figure 6 X-ray diffraction pattern of a dielectric thin film manufactured by a dielectric thin film manufacturing method according to an embodiment of this application;

[0054] Figure 7 The graph shows the dielectric constant of a dielectric film with different thicknesses at a measurement frequency of 1 MHz, obtained by a dielectric film manufacturing method according to an embodiment of this application.

[0055] Figure 8 Typical output characteristic curves of a dielectric film manufactured by a dielectric film manufacturing method according to an embodiment of this application when applied to a γ-Bi2O3 / MoS2FET.

[0056] Figure 9 Typical transport characteristic curves of a dielectric film manufactured by a dielectric film manufacturing method according to an embodiment of this application when applied to a γ-Bi2O3 / MoS2FET under a Vd of 1V. Detailed Implementation

[0057] As mentioned above, the preparation of high-k dielectric thin films suffers from problems such as easy surface contamination, high energy consumption, long reaction time, and difficulty in large-scale preparation. Therefore, this application provides a method for manufacturing dielectric thin films, as well as dielectric thin films and two-dimensional field-effect transistors, to solve the above problems.

[0058] This application provides a method for manufacturing a dielectric thin film, including the following steps:

[0059] Provide growth substrates and dielectric film raw materials;

[0060] Atomic-level stepped substrate: The growth substrate is annealed to form several steps that extend continuously and are regularly arranged along the crystal plane on the surface of the growth substrate, forming a macroscopically flat atomic-level stepped surface structure.

[0061] Growth of dielectric films: The growth substrate and dielectric film raw materials are annealed and oxidized together under reactive gas conditions. The dielectric film raw materials grow in an orderly manner along the steps and finally connect into a planar film structure to form a dielectric film.

[0062] This application also provides a dielectric film, manufactured using the dielectric film manufacturing method provided in this application; wherein, the dielectric film is a film with a monolithic structure formed by interconnecting crystal domains, and the crystal domains grow obliquely at a non-zero angle to the surface of the dielectric film; the maximum dielectric constant of the dielectric film can reach close to 40.

[0063] This application also provides a two-dimensional field-effect transistor, including the dielectric thin film provided in this application.

[0064] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In the description of this application, it should be noted that the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0065] Example 1

[0066] refer to Figure 1 This embodiment provides a method for manufacturing a dielectric thin film, including the following steps:

[0067] Provide growth substrates and dielectric film raw materials;

[0068] Atomic-level stepped substrate: The growth substrate is annealed to form several steps that extend continuously and are regularly arranged along the crystal plane on the surface of the growth substrate, forming a macroscopically flat atomic-level stepped surface structure.

[0069] The dielectric film is grown by annealing and oxidizing the growth substrate and the dielectric film raw materials together under reactive gas conditions. The dielectric film raw materials grow in an orderly manner along the surface structure of atomic-level steps, and finally connect into a planar film structure to form a dielectric film.

[0070] The dielectric thin film manufacturing method provided in this embodiment first anneales the growth substrate, forming several steps that extend continuously and are regularly arranged along the crystal planes on the surface of the growth substrate, constituting a macroscopically smooth atomic-level step surface structure. Due to its inherent properties, the sapphire substrate naturally forms such an atomic-level step surface structure after annealing. Thus, during the subsequent growth process, the dielectric thin film raw materials grow orderly along the steps, first forming dispersed crystal domains, which are then guided by the steps to form the same growth orientation. As the growth time progresses, they gradually connect into a single entity. Because the atomic-level step surface structure is macroscopically smooth, a smooth thin film can ultimately be formed. Furthermore, under these conditions, although Bi2O3 has multiple crystal forms, only body-centered cubic crystals can ultimately remain on the step surface for growth. Therefore, the final thin film contains only one crystal form, and due to the uniform orientation, the final thin film has no grain boundaries, resulting in a high-quality film with a high dielectric constant. Other methods in the prior art, such as using ALD deposition, result in thin films with various crystal forms and different growth directions, leading to various grain boundaries within the final film, making it difficult to achieve the superior performance of the thin film presented in this method. Furthermore, the dielectric film formed in this way can be grown under normal pressure, while other existing techniques typically require higher temperatures (900°C) and lower pressures (such as vacuum), whereas this method does not require these stringent conditions. Therefore, this method consumes less energy, has a shorter reaction time, and is suitable for large-scale preparation.

[0071] It should be further emphasized that in the atomic-level stepping process of this application, the growth substrate is directly annealed without undergoing any specific reaction with other special materials. This stepping process is a structural deformation of the growth substrate itself during high-temperature annealing. Furthermore, the atomic-level step surface structure formed by this process is only observable at the micrometer level using a high-powered microscope; it is difficult to detect with a macroscopic vision and is essentially perceived as a flat surface from a macroscopic perspective.

[0072] Specifically, in some embodiments of this application,

[0073] The growth substrate is a C-face sapphire substrate;

[0074] The dielectric film raw material is Bi powder;

[0075] The dielectric film is a γ-Bi2O3 film.

[0076] The dielectric thin film manufacturing method provided in this application exhibits excellent lattice constant compatibility between γ-Bi₂O₃ and the sapphire substrate, with a lattice mismatch value of only 5.2%. This ensures that after Bi powder is oxidized to γ-Bi₂O₃ during the reaction, it grows well along the extension direction of the steps on the sapphire substrate surface, achieving the same orientation and forming a body-centered cubic crystal. The resulting dielectric thin film is of superior quality, with a dielectric constant reaching a maximum of 39.38, approaching 40. This represents a significant improvement compared to existing technologies where HfO₂ dielectric films only reach 20 and Ta₂O₅ dielectric films only reach 25.

[0077] Taking the above material selection as an example, you can refer to... Figures 2-7 The solution of this embodiment will be further explained.

[0078] refer to Figure 2 The atomic force microscopy (AFM) image of the surface of the growth substrate after atomic-level stepping shows that the C-side sapphire substrate surface formed several neat step structures after annealing, which constitute an atomic-level step surface structure.

[0079] refer to Figure 3 The atomic force microscope image shown shows the dielectric film growing along the steps with the same orientation. It can be seen that the γ-Bi2O3 formed by oxidation grows along the extension direction of the steps on the surface of the sapphire substrate, and the growth orientation is the same at each position.

[0080] refer to Figures 4a-4c The optical microscope images shown depict the dielectric film reacting at different times during the process, revealing that, as... Figure 4a As shown, during the 20-minute period, γ-Bi₂O₃ formed dispersed crystal domains; with continued reaction, as... Figure 4b As shown, during the 40-minute period, the crystal domains continued to grow, essentially covering the entire field of view and gradually connecting into a unified structure; the reaction continued, as... Figure 4c As shown, during the 45-minute period, the film was completely connected into a single sheet. Because the atomic-level step surface structure of the sapphire substrate is macroscopically basically flat, the resulting dielectric film is also macroscopically basically flat.

[0081] For examples of adjacent crystal domains connecting to form a single unit, please refer to... Figures 5a-5c As can be seen in the same figure, the individual crystal domains are not completely independent, but gradually connect into one as they grow.

[0082] refer to Figure 6The X-ray diffraction pattern of the dielectric thin film manufactured by the manufacturing method of this embodiment is shown. The XRD test results are compared with the standard PDF card in the database. The (200) and (600) peaks correspond to the PDF card, indicating that the prepared material is a body-centered cubic γ-Bi2O3 crystal.

[0083] refer to Figure 7 The dielectric constant of the dielectric film manufactured by the method of this embodiment varies with different thicknesses. It can be seen that the highest dielectric constant can reach approximately 39.38, approaching 40.

[0084] Furthermore, in some embodiments of this application,

[0085] During the growth process, the dielectric thin film raw material forms an oxide thin film with a body-centered cubic crystal structure, and the corresponding crystals grow along the same orientation on different step surfaces.

[0086] The dielectric thin film manufacturing method provided in this application involves dielectric thin film raw materials that, during the growth step, form a body-centered cubic crystal structure with only one crystal form. Furthermore, the crystals grow along the same orientation on the surfaces of different steps, resulting in a thin film without grain boundaries. Therefore, the thin film has high quality and a high dielectric constant.

[0087] Furthermore, in some embodiments of this application,

[0088] During the atomic-level stepping process, the C-side sapphire substrate is annealed at 1400℃ for 4-6 hours.

[0089] The dielectric thin film manufacturing method provided in this application can form a well-morphological atomic-level step structure on the C-side sapphire substrate under annealing conditions at 1400℃ for 4-6 hours, which is beneficial for subsequent growth of the dielectric thin film. If the annealing time is less than 4 hours, it is difficult to form steps; if the annealing time is greater than 6 hours, it results in waste.

[0090] Furthermore, in some embodiments of this application,

[0091] During the growth of the dielectric film, the oxygen content in the reaction environment is less than or equal to 50 ppm.

[0092] The dielectric thin film manufacturing method provided in this application controls the oxygen content in the reaction environment to be less than or equal to 50 ppm. Therefore, it can be ensured that only a very small amount of Bi powder reacts to form Bi2O3 before reaching the set growth temperature. This Bi2O3 includes various other crystal forms, but is difficult to retain on the step surface. After reaching the growth temperature, the remaining Bi powder reacts with oxygen to mainly form body-centered cubic Bi2O3. Other crystal forms are extremely rare and difficult to retain, thus ensuring the uniqueness of the crystal form in the final thin film.

[0093] Furthermore, in some embodiments of this application,

[0094] The steps of growing a dielectric thin film include:

[0095] A container (e.g., a quartz boat) containing dielectric film raw materials is placed in the heating zone of a reaction apparatus (e.g., a tube furnace). Simultaneously, a growth substrate forming atomic-level steps is placed downstream within the reaction apparatus, and an inert gas is introduced to purge the air from the reaction apparatus. Then, an argon-oxygen mixture is introduced into the reaction apparatus as a carrier gas, and the heating zone is raised to the reaction temperature. The reaction is continued for a period of time, allowing the dielectric film raw materials to grow orderly along the surface structure of the atomic-level steps, eventually forming a planar thin film structure, thus creating a dielectric film.

[0096] Furthermore, in some embodiments of this application,

[0097] The amount of dielectric film raw material is 40mg to 60mg;

[0098] The argon-oxygen mixed gas was introduced at a rate of 250 sccm to 350 sccm.

[0099] The reaction temperature is 600℃~700℃; the reaction time is 30min~45min;

[0100] The heating rate to the reaction temperature is 20℃ / min to 30℃ / min.

[0101] If the above conditions are below the lower limit, it will be difficult to form a continuous thin film; if they exceed the upper limit, it will result in waste and cause accumulation at the crystal domain junctions, affecting the quality of the thin film.

[0102] Example 2

[0103] This embodiment provides a dielectric film manufactured using the dielectric film manufacturing method provided in Embodiment 1 above.

[0104] in,

[0105] A dielectric thin film is a thin film with several crystal domains connected to form an integral structure. The crystal domains grow obliquely at a non-zero angle to the surface of the dielectric thin film.

[0106] The dielectric film provided in this embodiment is manufactured using the dielectric film manufacturing method provided in this application. The growth substrate is first annealed to form several steps that extend continuously and are regularly arranged along the crystal planes on its surface, constituting a macroscopically smooth atomic-level step surface structure. Due to its inherent properties, the sapphire substrate naturally forms such an atomic-level step surface structure after annealing. Thus, during subsequent growth, the dielectric film raw material grows along the steps, initially forming dispersed crystal domains, which are then guided by the steps to form the same growth orientation. As growth progresses, they gradually connect into a single structure. Because the atomic-level step surface structure is macroscopically smooth, a smooth film can ultimately be formed. Furthermore, under these conditions, although Bi₂O₃ has multiple crystal forms, only body-centered cubic crystals can ultimately remain on the step surface for growth. Therefore, the final film contains only one crystal form, and due to the uniform orientation, the final film has no grain boundaries, resulting in high-quality film with a high dielectric constant. Other existing methods, such as ALD deposition, result in films with various crystal structures and different growth directions, leading to the presence of grain boundaries within the film and making it difficult to achieve the superior performance of the film produced by this method. Furthermore, the dielectric film formed in this way can be grown under ambient pressure, while other existing methods require higher temperatures (900°C) and lower pressures (such as vacuum), whereas this method eliminates these stringent conditions. Therefore, it consumes less energy, has a shorter reaction time, and is suitable for large-scale fabrication.

[0107] Furthermore, in some embodiments of this application,

[0108] A dielectric film is composed of oxide crystals of dielectric film raw materials with a body-centered cubic structure; the growth orientation of the oxide crystals of dielectric film raw materials is the same at any position in the dielectric film.

[0109] The dielectric film provided in this application is composed of oxide crystals of dielectric film raw materials with a body-centered cubic structure. Furthermore, the growth orientation of the oxide crystals of the dielectric film raw materials is the same at any location on the dielectric film, and only one crystal form, body-centered cubic, exists. Therefore, there are no grain boundaries within the film. Consequently, the film has high quality and a high dielectric constant.

[0110] Example 3

[0111] This embodiment also provides a two-dimensional field-effect transistor, including the dielectric thin film provided in Embodiment 2 above.

[0112] For example, a two-dimensional field-effect transistor uses the dielectric thin film provided in Example 2 above as a γ-Bi₂O₃ / MoS₂ FET co-formed with MoS₂. Its electrical output characteristic curve is shown below. Figure 8 As shown in the figure. It can be seen from the figure that increasing the gate voltage V... g I dThe value also increases accordingly, indicating that the γ-Bi₂O₃ dielectric has a good control effect on the transistor. Its value at V... d A typical transfer characteristic curve for 1V is shown below. Figure 9 As shown in the figure, the subthreshold swing is 80 mV / dec, which is close to the thermodynamic limit of 60 mV / dec. th The voltage is -0.7V, and the operating voltage is within 1V, indicating low power consumption.

[0113] The two-dimensional field-effect transistor provided in this embodiment uses the dielectric thin film provided in this application. The dielectric thin film preparation process has low energy consumption and short reaction time, making it suitable for large-scale preparation. Moreover, the thin film has good quality and high dielectric constant. Therefore, the two-dimensional field-effect transistor based on this dielectric thin film can achieve a subthreshold swing of 80mV / dec, which is close to the thermodynamic limit. Compared with devices using traditional high-k dielectrics, it exhibits higher performance.

[0114] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A method for manufacturing a dielectric thin film, characterized in that, Includes the following steps: Provide growth substrates and dielectric film raw materials; Atomic-level stepped substrate: The growth substrate is annealed to form several steps that extend continuously and are regularly arranged along the crystal plane on the surface of the growth substrate, forming a macroscopically flat atomic-level stepped surface structure. Growth of dielectric film: The growth substrate and the dielectric film raw material are annealed and oxidized together under reactive gas conditions. The oxidized dielectric film raw material grows in an orderly manner along the steps and finally connects into a planar film structure to form the dielectric film. in, The growth substrate is a C-faceted sapphire substrate; The dielectric film raw material is Bi powder; The dielectric film is a γ-Bi2O3 film; In the step of growing the dielectric film, the oxygen content in the reaction environment is less than or equal to 50 ppm.

2. The method for manufacturing a dielectric thin film according to claim 1, characterized in that, The oxidized dielectric film raw material forms an oxide film with a body-centered cubic crystal structure during the growth process, and the corresponding crystals grow along the same orientation on different step surfaces.

3. The method for manufacturing a dielectric thin film according to claim 1, characterized in that, During the atomic-level stepping process, the C-plane sapphire substrate is annealed at 1400℃ for 4-6 hours.

4. The method for manufacturing a dielectric thin film according to claim 1, characterized in that, The step of growing the dielectric thin film includes: A container containing the dielectric film raw material is placed in the heating zone of the reaction apparatus. Simultaneously, the growth substrate forming atomic-level steps is placed downstream of the reaction apparatus, and an inert gas is introduced to purge the air from the reaction apparatus. Then, an argon-oxygen mixture is introduced into the reaction apparatus as a carrier gas, and the heating zone is raised to the reaction temperature. The reaction is continued for a period of time, allowing the oxidized dielectric film raw material to grow orderly along the steps, eventually forming a planar thin film structure, thus forming the dielectric film.

5. The method for manufacturing a dielectric thin film according to claim 4, characterized in that, The amount of the dielectric film raw material is 40mg~60mg; The argon-oxygen mixed gas is introduced at a rate of 250 sccm to 350 sccm; The reaction temperature is 600℃~700℃; the reaction time is 30min~45min; The heating rate to the reaction temperature is 20℃ / min to 30℃ / min.

6. A dielectric thin film, characterized in that, Manufactured using the dielectric thin film manufacturing method according to any one of claims 1-5; wherein... The dielectric film is a film with a monolithic structure formed by connecting crystal domains; The crystal domains grow obliquely at a non-zero angle to the surface of the dielectric film.

7. The dielectric thin film according to claim 6, characterized in that, The dielectric film is composed of oxide crystals of dielectric film raw material with a body-centered cubic structure; the growth orientation of the oxide crystals of dielectric film raw material is the same at any position of the dielectric film.

8. A two-dimensional field-effect transistor, characterized in that, Includes the dielectric film as described in claim 6 or 7.

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