Thin film preparation method, thin film transistor and preparation method of thin film transistor

Abstract

The invention discloses a thin film preparation method, a thin film transistor and a preparation method thereof. A method for preparing a metal oxide semiconductor thin film, where the method includes: performing a plurality of deposition cycles to form a metal oxide semiconductor thin film of a desired thickness on an interface region, where performing one deposition cycle includes depositing a metal precursor using an atomic layer deposition technique and oxidizing the metal precursor; and repairing an interface defect in the metal oxide semiconductor thin film with a sulfur-containing reactant in at least one of the plurality of deposition cycles.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, specifically to a thin film preparation method and a thin film transistor and the preparation method thereof. Background Technology

[0002] With the rapid development of information technology, amorphous oxide semiconductor (AOS) thin-film transistors (TFTs) are becoming a core technology for realizing the integration of sensing, storage, and computing. In this innovative application scenario, AOS TFTs not only possess excellent photoresponse characteristics, enabling them to effectively sense and process light signals from the environment, but they can also be tightly integrated with neural network architectures to form self-learning and adaptive intelligent systems that analyze and respond to external data in real time, significantly improving data processing efficiency and response speed. Furthermore, the extremely low thermal budget of AOS TFTs ensures excellent compatibility in back-end processes, allowing for seamless integration into existing semiconductor manufacturing processes and supporting the construction of complex 3D integrated circuits. This technological advancement not only lays the foundation for the operation of high-performance intelligent devices but will also drive the emergence of computing platforms, opening up broad application prospects in cutting-edge fields such as the Internet of Things, artificial intelligence, and edge computing, thereby promoting the popularization and deepening of intelligent technologies.

[0003] Despite the numerous advantages of AOS TFTs, their manufacturing process still faces several challenges. Metal-oxide-semiconductor (MO) structures are relatively complex, with metal-oxygen (MO) bonds as the primary structural component, determining the material's conductivity and stability. In this disordered amorphous structure, oxygen vacancies (Vo) are one of the main defects, potentially leading to the formation of free carriers or electron traps. This is especially true in thin-film transistors (TFTs), where the interface between the MO and gate dielectric is even more complex, often exhibiting metal dangling bonds (M-Vo) caused by oxygen vacancies, oxygen-free bonds between metal atoms (M1-Vo-M2), and oxygen dangling bonds (O:) caused by metal mismatch. These bonds can act as charge traps, capturing carriers and inducing scattering, leading to decreased mobility and hysteresis. Therefore, interface defects not only degrade device performance but also cause problems such as threshold voltage drift and subthreshold swing degradation, adversely affecting the long-term performance of TFTs. Thus, one of the key aspects of ensuring the excellent and stable performance of back-end compatible AOS-TFTs is to achieve effective control over interface defects. Especially for advanced node technologies, as the size shrinks, interface control becomes even more important. Summary of the Invention

[0004] It should be understood that the above general description and the following detailed description of the invention are exemplary and illustrative, and are intended to provide further explanation of the invention as described in the claims.

[0005] According to a first aspect of the present invention, a method for preparing a metal oxide semiconductor thin film is provided, wherein the method comprises: performing a plurality of deposition cycles to form a metal oxide semiconductor thin film of desired thickness on an interface region, wherein performing one of the deposition cycles comprises depositing a metal precursor using atomic layer deposition and oxidizing the metal precursor; and in at least one of the plurality of deposition cycles, using a sulfur-containing reactant to repair interface defects in the metal oxide semiconductor thin film.

[0006] In the above method, the metal precursor includes a first precursor, wherein depositing the metal precursor using atomic layer deposition (ALD) and oxidizing the metal precursor includes performing the following steps: (1) depositing the first precursor on an interface region using ALD; (2) performing an inert gas purging to remove unreacted first precursor; (3) introducing an oxygen-containing reactant to oxidize the first precursor; and (4) performing an inert gas purging to remove unreacted oxygen-containing reactant.

[0007] In the above method, using sulfur-containing reactants to repair interface defects in the metal oxide semiconductor thin film includes performing the following steps: after step (4), introducing sulfur-containing reactants to passivate oxygen vacancies in the metal oxide generated after oxidation of the first precursor; and performing inert gas purging to remove unreacted sulfur-containing reactants.

[0008] In the above method, the metal precursor includes a first precursor, wherein depositing the metal precursor using atomic layer deposition (ALD) and oxidizing the metal precursor includes performing at least one first sub-cycle, and performing one first sub-cycle includes performing the following steps: (A1) depositing the first precursor on an interface region using ALD; (A2) performing an inert gas purging to remove unreacted first precursor; (A3) introducing an oxygen-containing reactant to oxidize the first precursor; and (A4) performing an inert gas purging to remove unreacted oxygen-containing reactant.

[0009] In the above method, the metal precursor further includes a second precursor, wherein depositing the metal precursor using atomic layer deposition and oxidizing the metal precursor further includes performing at least one second sub-cycle after the at least one first sub-cycle, and performing a second sub-cycle includes performing the following steps: (B1) depositing the second precursor on the interface region using atomic layer deposition after step (A4); (B2) performing inert gas purging to remove unreacted second precursor; (B3) introducing oxygen-containing reactants to oxidize the second precursor; and (B4) performing inert gas purging to remove unreacted oxygen-containing reactants.

[0010] In the above method, using sulfur-containing reactants to repair interface defects in the metal oxide semiconductor thin film includes performing the following steps: after step (B4), introducing sulfur-containing reactants to passivate oxygen vacancies in the metal oxide generated after oxidation of the second precursor; and performing inert gas purging to remove unreacted sulfur-containing reactants.

[0011] In the above method, using sulfur-containing reactants to repair interface defects in the metal oxide semiconductor thin film includes performing the following steps: introducing sulfur-containing reactants after step (A4) and before step (B1) to passivate oxygen vacancies in the metal oxide generated after oxidation of the first precursor; and performing inert gas purging to remove unreacted sulfur-containing reactants.

[0012] In the above method, the method further includes performing the following steps in at least one of the plurality of deposition cycles: after step (B4), introducing sulfur-containing reactants to passivate oxygen vacancies in the metal oxide generated after oxidation of the second precursor; and performing inert gas purging to remove unreacted sulfur-containing reactants.

[0013] In the above method, the metal oxide semiconductor thin film includes one of the following: binary metal oxide, ternary metal oxide, or metal oxide with more than three elements.

[0014] In the above method, the sulfur-containing reactant is a sulfur-containing inorganic gas or a thiol-based organic compound.

[0015] In the above method, the desired thickness does not exceed 1 nm.

[0016] According to a second aspect of the present invention, a thin-film transistor is provided, comprising: a substrate; a gate dielectric; a channel layer; a metal source / drain and a metal gate; and a sulfur-based modified metal-oxide-semiconductor interface layer located between the gate dielectric and the channel layer, wherein the sulfur-based modified metal-oxide-semiconductor interface layer is prepared by using a method as described in any one of the above methods.

[0017] In the aforementioned thin-film transistors, the thin-film transistors are top-gate structures, bottom-gate structures, ring-gate structures, or vertical ring-channel structures.

[0018] According to a third aspect of the present invention, a method for fabricating a thin-film transistor is provided, wherein the method comprises: fabricating a substrate; and fabricating on the substrate a gate dielectric, a channel layer, a metal source / drain and a metal gate, and a sulfur-modified metal-oxide-semiconductor interface layer located between the gate dielectric and the channel layer, wherein the sulfur-modified metal-oxide-semiconductor interface layer is fabricated using a method as described in any of the above methods.

[0019] In the above method, the channel layer and the sulfur-modified metal oxide semiconductor interface layer are prepared in different reaction chambers.

[0020] According to a fourth aspect of the present invention, a system for preparing a metal oxide semiconductor thin film is provided, comprising a deposition cycle execution unit and an interface defect repair unit, the system being configured to perform the following steps: using the deposition cycle execution unit to perform a plurality of deposition cycles to form a metal oxide semiconductor thin film of desired thickness on an interface region, wherein performing one of the deposition cycles comprises depositing a metal precursor using atomic layer deposition and oxidizing the metal precursor; and using the interface defect repair unit to repair interface defects in the metal oxide semiconductor thin film using a sulfur-containing reactant in at least one of the plurality of deposition cycles. Attached Figure Description

[0021] The accompanying drawings are included to provide a further understanding of the invention; they are incorporated into and constitute a part of this application. The drawings illustrate embodiments of the invention and, together with this specification, serve to explain the principles of the invention. In the drawings:

[0022] Figure 1 This is a schematic diagram of the structure of a TFT according to an embodiment of this application;

[0023] Figure 2 This is a flowchart of a method for preparing a metal oxide semiconductor thin film according to an embodiment of this application;

[0024] Figure 3 This is a schematic flowchart of a method for preparing a metal oxide semiconductor thin film according to the first embodiment of this application;

[0025] Figures 4A-4B This is a schematic flowchart of a method for preparing a metal oxide semiconductor thin film according to a second embodiment of this application;

[0026] Figures 5A-5BThis is a schematic flowchart of a method for preparing a metal oxide semiconductor thin film according to the third embodiment of this application;

[0027] Figures 6A-6B This is a schematic flowchart of a method for preparing a metal oxide semiconductor thin film according to the fourth embodiment of this application; and

[0028] Figure 7 This is a block diagram of a system for preparing metal oxide semiconductor thin films according to an embodiment of this application. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0030] For ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “up,” etc., may be used herein to describe the relationship of one element or feature relative to another element or feature as shown in the figure. It should be understood that spatial relative terms are intended to include different orientations of the device used or operated in addition to those shown in the figure. For example, if the device in the figure were flipped, an element described as “below” or “under” other elements or features would be oriented as “above” other elements or features.

[0031] Unless otherwise specified, the terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms should be understood to have the meaning consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formalized manner, unless explicitly stated otherwise herein.

[0032] To effectively control interface defects, this application proposes using atomic layer deposition (ALD) to prepare metal-oxide-semiconductor (MODS) interface layers. ALD, due to its layer-by-layer growth mechanism, offers atomic-level thickness control and excellent uniformity, and its relatively low deposition temperature (generally not exceeding 400°C), making it a preferred method for fabricating back-end compatible AOS-TFTs at advanced nodes. ALD precisely controls the introduction of reactants and chemical reactions, depositing only one monolayer in each deposition cycle. Therefore, precise control of interface defects can be achieved by adjusting the types of reactants and the deposition cycle positions.

[0033] In order to control the interface defects between metal oxide semiconductors and gate dielectrics, this application innovatively proposes to introduce sulfur elements in situ at specific locations of the thin film during the growth process cycle, thereby achieving defect repair and interface optimization.

[0034] Figure 1 This is a schematic diagram of the structure of a TFT according to an embodiment of this application. (a) is a TFT with a bottom-gate structure, and (b) is a TFT with a top-gate structure. Although Figure 1 Only two TFT structures are shown, but TFTs can also adopt other suitable structures, such as gate-all-around (GAA) or channel-all-around (CAA).

[0035] As shown in section (a), a bottom-gate TFT may include a substrate 100, a metal gate 101, a gate dielectric 102, a channel layer 103, a metal source / drain 104, and a sulfur-modified metal-oxide-semiconductor interface layer 120. The substrate 100 may be made of materials such as silicon, thermally heated silicon oxide, quartz, or sapphire. The metal gate 101 may be deposited using physical vapor deposition (PVD), ALD, or other methods, and may include metal materials such as W, Mo, TiN, TaN, and Ru. The gate dielectric 102 may be deposited using ALD and may include materials such as alumina, hafnium oxide, zirconium oxide, silicon nitride, and their doped thin films. The sulfur-modified metal-oxide-semiconductor interface layer 120 is located between the gate dielectric 102 and the channel layer 103 and can be achieved by introducing a sulfur-containing reactant during the ALD process. The sulfur-containing reactant may include inorganic gases such as H2S and SO2, or thiol-based organic compounds such as methanethiol, ethanethiol, and ethylenedithiol. The channel layer 103 is made of AOS material and is deposited after the deposition of the sulfur-modified metal oxide semiconductor interface layer 120. The metal source / drain 104 can be deposited using methods such as PVD or ALD, and can include materials such as W, Mo, Au, Ti, TiN, Al, and Cu. The bottom-gate TFT may also include a passivation layer 105, located on the surface of the channel layer 103. This passivation layer 105 can include inorganic materials such as silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, and silicon phosphosilicate glass, or organic thin films such as polyimide. It can be deposited using chemical vapor deposition (CVD), ALD, or by spin coating or spraying. In the bottom-gate TFT, the gate dielectric 102 is formed before the channel layer 103.

[0036] As shown in section (b), the top-gate TFT may include a substrate 110, a channel layer 111, a gate dielectric 112, a metal gate 113, a metal source / drain 114, and a sulfur-modified metal oxide semiconductor interface layer 140. The substrate 110 may be made of materials such as silicon, thermally heated silicon oxide, quartz, or sapphire. The channel layer 111 is made of AOS. The sulfur-modified metal oxide semiconductor interface layer 140 is located between the channel layer 111 and the gate dielectric 112, and can be achieved by using sulfur-containing reactants in the ALD deposition cycle of the oxide semiconductor. The sulfur-containing reactants may include inorganic gases such as H2S and SO2, or thiol-based organic compounds such as methanethiol, ethanethiol, and ethylenedithiol. The gate dielectric 112 may be deposited via ALD and may include high-dielectric-constant insulating media such as alumina, hafnium oxide, or silicon nitride. The metal source / drain 114 can be deposited using methods such as PVD or ALD, and can include low-resistivity metals such as W, Mo, Au, Ti, TiN, Al, and Cu. The metal gate 113 can be deposited using PVD, and can include metal materials such as W, Mo, TiN, TaN, and Ru. In a top-gate TFT structure, the gate dielectric 112 is formed after the channel layer 111.

[0037] The following discusses methods for preparing sulfur-modified metal-oxide-semiconductor interface layers.

[0038] Figure 2 This is a flowchart of a method 200 for preparing a metal oxide semiconductor thin film according to an embodiment of this application.

[0039] At step 202, multiple deposition cycles may be performed to form a metal oxide semiconductor thin film of a desired thickness on the interface region, wherein performing one deposition cycle includes depositing a metal precursor using atomic layer deposition and oxidizing the metal precursor. In one embodiment, the desired thickness of the metal oxide semiconductor thin film is no more than 1 nm.

[0040] At step 204, sulfur-containing reactants can be used to repair interface defects in metal oxide semiconductor films in at least one of multiple deposition cycles.

[0041] After depositing and oxidizing the metal precursor, the weak Coulomb force between the large-sized metal cations and oxygen anions leads to the easy desorption of oxygen atoms from the metal, resulting in oxygen vacancies, additional electron doping, and deep-level traps. However, sulfur has lower electronegativity and tends to form stable covalent bonds with metal atoms. Furthermore, sulfur has a larger atomic radius; incorporating sulfur into the existing metal oxide lattice causes lattice distortion, which increases the energy required to form oxygen vacancies, thus suppressing oxygen vacancy (Vo) formation. By introducing sulfur-containing reactants during ALD deposition, oxygen vacancies in the metal oxide formed after oxidation of the metal precursor can be filled and suppressed, passivating defects caused by metal dangling bonds and improving the structural stability of the thin film. Compared with traditional physical vapor deposition (PVD) methods such as magnetron sputtering and oxygen-environment annealing, the ALD process employed in this application significantly reduces interface defect states and dangling bonds, improving the long-term stability and reliability of AOS thin-film transistors.

[0042] In one embodiment, the metal oxide semiconductor thin film can be one of the following: a binary metal oxide, a ternary metal oxide, or a metal oxide with three or more elements. For example, the binary metal oxide can be indium oxide (In₂O₃), zinc oxide (ZnO), tin oxide (SnO₂), etc., and the ternary and higher metal oxides can be indium gallium zinc oxide (IGZO), indium tin oxide (ITO), indium gallium tin oxide (IGTO), indium zinc tin oxide (IZTO), etc. In one embodiment, the sulfur-containing reactant can be a sulfur-containing inorganic gas or a thiol-based organic compound. For example, the sulfur-containing inorganic gas can include inorganic gases such as H₂S and SO₂, and the thiol-based organic compound can include methanethiol, ethanethiol, ethylene dithiol, etc.

[0043] Figure 3 This is a schematic flowchart of a method for preparing a metal oxide semiconductor thin film according to the first embodiment of this application. The following discussion focuses on metal oxide semiconductor thin films comprising binary metal oxides.

[0044] In one embodiment, the metal precursor may include metal precursor A, and depositing the metal precursor using atomic layer deposition and oxidizing the metal precursor may include performing the following steps:

[0045] In step 3A, a metal precursor A is deposited on the interface region 300 using atomic layer deposition (ALD) technology to ensure sufficient adsorption on the interface region 300. The circled A represents the metal precursor A. Depending on the different TFT structures, the interface region 300 can be the gate dielectric surface, the channel layer surface, or other suitable locations. The metal precursor A can be a conventional AOS precursor, such as triethylindium, trimethylgallium, diethylzinc, etc.

[0046] At step 3B, after one pulse of ALD of metal precursor A, an inert gas purging is performed to remove unreacted metal precursor A. The inert gas can be nitrogen or argon, etc.

[0047] In step 3C, an oxygen-containing reactant is introduced to react with the metal precursor A in an oxidation reaction. The hollow circles represent the oxygen-containing reactant. The oxygen-containing reactant can be a source of H₂O, O₃, etc. Due to the limitations of the oxidation reaction during deposition, oxygen vacancies may form in the metal oxide generated after the oxidation of the metal precursor A.

[0048] In step 3D, an inert gas purging is performed to remove unreacted oxygen-containing reactants. The inert gas can be nitrogen or argon, etc.

[0049] In one embodiment, repairing interface defects in metal oxide semiconductor thin films using sulfur-containing reactants may include performing the following steps:

[0050] Following step 3D, in step 3E, a sulfur-containing reactant S is introduced to passivate oxygen vacancies in the metal oxide formed after oxidation of the metal precursor A. The circled S represents the sulfur-containing reactant S. The sulfur-containing reactant S can be inorganic gases such as H₂S and SO₂, or thiol-based organic compounds such as methanethiol, ethanethiol, and ethylenedithiol. The sulfur-containing reactant S can participate in interfacial reactions to locally repair interfacial defects in metal oxide semiconductor thin films.

[0051] At step 3F, an inert gas purging is performed to remove unreacted sulfur-containing reactants S. The inert gas can be nitrogen or argon, etc.

[0052] It should be understood that, although Figure 3 The schematic diagram of step 3F only represents the completion of one deposition cycle, but multiple deposition cycles can be performed to achieve a metal oxide semiconductor thin film containing the metal precursor A of the desired thickness, and sulfur-containing reactants can be used in any one or more of the multiple deposition cycles to repair interface defects in the metal oxide semiconductor thin film. For example, repair can be performed in every deposition cycle, in a subset of deposition cycles, or only in the last deposition cycle, and so on.

[0053] The above methods can be used to prepare sulfide-modified metal oxide semiconductor thin films containing binary metal oxides.

[0054] Figures 4A-4B This is a schematic flowchart of a method for preparing a metal oxide semiconductor thin film according to a second embodiment of this application. The following discussion focuses on metal oxide semiconductor thin films comprising ternary metal oxides.

[0055] In one embodiment, the metal precursor includes metal precursor A. Depositing the metal precursor using atomic layer deposition and oxidizing the metal precursor may include performing at least one first sub-loop. Performing a first sub-loop includes performing the following steps:

[0056] like Figure 4A As shown, in step 4A, a metal precursor A is deposited on the interface region 300 using atomic layer deposition (ALD) technology to ensure sufficient adsorption on the interface region 300. The circled A represents the metal precursor A. Depending on the different TFT structures, the interface region 300 can be the gate dielectric surface, the channel layer surface, or other suitable locations. The metal precursor A can be a conventional AOS precursor, such as triethylindium, trimethylgallium, diethylzinc, etc.

[0057] At step 4B, after one pulse of ALD of metal precursor A, an inert gas purging is performed to remove unreacted metal precursor A. The inert gas can be nitrogen or argon, etc.

[0058] In step 4C, an oxygen-containing reactant is introduced to react with the metal precursor A in an oxidation reaction. The hollow circles represent the oxygen-containing reactant. The oxygen-containing reactant can be a source of H₂O, O₃, etc.

[0059] In step 4D, an inert gas purging is performed to remove unreacted oxygen-containing reactants. The inert gas can be nitrogen or argon, etc.

[0060] After at least one first sub-loop has completed execution, the desired amount of metal precursor A can be deposited. To avoid redundancy, although... Figure 4A The schematic diagram of step 4D shows only one layer of metal precursor A and one layer of oxygen, but it can represent the completion of at least one first sub-cycle, that is, the completion of the deposition of multiple layers of metal precursor A and multiple layers of oxygen.

[0061] In one embodiment, the metal precursor further includes metal precursor B, and depositing the metal precursor using atomic layer deposition and oxidizing the metal precursor further includes executing at least one second sub-cycle after at least one first sub-cycle, wherein executing a second sub-cycle includes performing the following steps:

[0062] like Figure 4B As shown, after step 4D, at step 4E, a metal precursor B is deposited on the interface region 300 using atomic layer deposition (ALD) technology to ensure sufficient adsorption on the interface region 300. The circled B represents the metal precursor B. The metal precursor B can be a conventional AOS precursor, such as triethylindium, trimethylgallium, diethylzinc, etc.

[0063] At step 4F, after a pulse of ALD in the metal precursor B, an inert gas purging is performed to remove unreacted metal precursor B. The inert gas can be nitrogen or argon, etc.

[0064] In step 4G, an oxygen-containing reactant is introduced to oxidize the metal precursor B. Hollow circles represent the oxygen-containing reactant. The oxygen-containing reactant can be a source of H₂O, O₃, etc. Due to the limitations of the oxidation reaction during deposition, oxygen vacancies may form in the metal oxide generated after the oxidation of the metal precursor B.

[0065] In step 4H, an inert gas purging is performed to remove unreacted oxygen-containing reactants. The inert gas can be nitrogen or argon, etc.

[0066] After at least one second sub-loop has completed execution, the desired amount of metal precursor B can be deposited. To avoid redundancy, although... Figure 4B The schematic diagram of step 4H shows only one layer of metal precursor B and one layer of oxygen, but it can represent the completion of at least one second sub-cycle, that is, the completion of the deposition of multiple layers of interleaved metal precursor B and multiple layers of oxygen. Therefore, Figure 4B The schematic diagram of step 4H in the diagram represents the completion of a deposition cycle of metal precursor A and metal precursor B.

[0067] The number of first and second sub-cycles in a deposition cycle depends on the composition of the metal oxide. For example, for a metal oxide A containing metal elements A and B in an elemental ratio of x:y... x B y O, a deposition cycle consists of x first sub-cycles of metal element A and y second sub-cycles of metal element B. Therefore, Figure 4B The diagram of step 4H in the diagram can represent the completion of the execution of x first sub-loops of metal element A and y second sub-loops of metal element B.

[0068] In one embodiment, repairing interface defects in metal oxide semiconductor thin films using sulfur-containing reactants may include performing the following steps:

[0069] Following step 4H, at step 4I, a sulfur-containing reactant S is introduced to passivate oxygen vacancies in the metal oxide formed after oxidation of the metal precursor B. The circled S represents the sulfur-containing reactant S. The sulfur-containing reactant S can be inorganic gases such as H₂S and SO₂, or thiol-based organic compounds such as methanethiol, ethanethiol, and ethylenedithiol. The sulfur-containing reactant S can participate in interfacial reactions to locally repair interfacial defects in metal oxide semiconductor thin films.

[0070] At step 4J, an inert gas purging is performed to remove unreacted sulfur-containing reactants S. The inert gas can be nitrogen or argon, etc.

[0071] Although Figures 4A-4B Only one deposition cycle including metal precursor A and metal precursor B is shown; however, it should be understood that multiple deposition cycles can be performed to form a metal oxide semiconductor film of desired thickness, and sulfur-containing reactants can be used in any one or more of the multiple deposition cycles to repair interface defects in the metal oxide semiconductor film. For example, repair can be performed in every deposition cycle, in a subset of deposition cycles, or only in the last deposition cycle, and so on.

[0072] The above method can be used to prepare metal oxide semiconductor thin films containing ternary metal oxides, wherein interface defects in the metal oxide semiconductor thin films are repaired in any one or more deposition cycles.

[0073] Figures 5A-5B This is a schematic flowchart of a method for preparing a metal oxide semiconductor thin film according to a third embodiment of this application.

[0074] In one embodiment, the metal precursor includes metal precursor A. Depositing the metal precursor using atomic layer deposition and oxidizing the metal precursor may include performing at least one first sub-loop. Performing a first sub-loop includes performing the following steps:

[0075] like Figure 5A As shown, in step 5A, a metal precursor A is deposited on the interface region 300 using atomic layer deposition (ALD) technology to ensure sufficient adsorption on the interface region 300. The circled A represents the metal precursor A. Depending on the different TFT structures, the interface region 300 can be the gate dielectric surface, the channel layer surface, or other suitable locations. The metal precursor A can be a conventional AOS precursor, such as triethylindium, trimethylgallium, diethylzinc, etc.

[0076] At step 5B, after one pulse of ALD of metal precursor A, an inert gas purging is performed to remove unreacted metal precursor A. The inert gas can be nitrogen or argon, etc.

[0077] In step 5C, an oxygen-containing reactant is introduced to react with the metal precursor A in an oxidation reaction. The hollow circles represent the oxygen-containing reactant. The oxygen-containing reactant can be a source of H₂O, O₃, etc.

[0078] In step 5D, an inert gas purging is performed to remove unreacted oxygen-containing reactants. The inert gas can be nitrogen or argon, etc.

[0079] After at least one first sub-loop has completed execution, the desired amount of metal precursor A can be deposited. To avoid redundancy, Figure 5A The schematic diagram of step 5D shows only one layer of metal precursor A and one layer of oxygen, but it can represent the completion of at least one first sub-cycle, that is, the completion of the deposition of multiple layers of metal precursor A and multiple layers of oxygen.

[0080] In one embodiment, repairing interface defects in metal oxide semiconductor thin films using sulfur-containing reactants may include performing the following steps:

[0081] Following step 5D, in step 5E, a sulfur-containing reactant S is introduced to passivate oxygen vacancies in the metal oxide formed after oxidation of the metal precursor A. The circled S represents the sulfur-containing reactant S. The sulfur-containing reactant S can be inorganic gases such as H₂S and SO₂, or thiol-based organic compounds such as methanethiol, ethanethiol, and ethylenedithiol. The sulfur-containing reactant S can participate in interfacial reactions to locally repair interfacial defects in metal oxide semiconductor thin films.

[0082] At step 5F, an inert gas purging is performed to remove unreacted sulfur-containing reactants S. The inert gas can be nitrogen or argon, etc.

[0083] In one embodiment, the metal precursor further includes metal precursor B, wherein depositing the metal precursor using atomic layer deposition and oxidizing the metal precursor further includes executing at least one second sub-cycle after at least one first sub-cycle, wherein executing a second sub-cycle includes performing the following steps:

[0084] like Figure 5B As shown, after step 5F, in step 5G, a metal precursor B is deposited on the interface region 300 using atomic layer deposition (ALD) technology to ensure sufficient adsorption on the interface region 300. The circled B represents the metal precursor B. The metal precursor B can be a conventional AOS precursor, such as triethylindium, trimethylgallium, diethylzinc, etc.

[0085] At step 5H, after a pulse of ALD of the metal precursor B, an inert gas purging is performed to remove unreacted metal precursor B. The inert gas can be nitrogen or argon, etc.

[0086] In step 5I, an oxygen-containing reactant is introduced to react with the metal precursor B in an oxidation reaction. Hollow circles represent the oxygen-containing reactant. The oxygen-containing reactant can be a source of H₂O, O₃, etc. Due to the limitations of the oxidation reaction during deposition, oxygen vacancies may form in the metal oxide generated after the oxidation of the metal precursor B.

[0087] At step 5J, an inert gas purging is performed to remove unreacted oxygen-containing reactants. The inert gas can be nitrogen or argon, etc.

[0088] After at least one second sub-loop has completed execution, the desired amount of metal precursor B can be deposited. To avoid redundancy, Figure 5B The schematic diagram of step 5J shows only one layer of metal precursor B and one layer of oxygen, but it can represent the completion of at least one second sub-cycle, that is, the completion of the deposition of multiple layers of interleaved metal precursor B and multiple layers of oxygen. Therefore, Figure 5B The schematic diagram of step 5J in the diagram represents the completion of a deposition cycle of metal precursor A and metal precursor B.

[0089] The number of first and second sub-cycles in a deposition cycle depends on the composition of the metal oxide. For example, for a metal oxide A containing metal elements A and B in an elemental ratio of x:y... x B y O, a deposition cycle consists of x first sub-cycles of metal element A and y second sub-cycles of metal element B. Therefore, Figure 5B The schematic diagram of step 5J in the diagram can represent the completion of the execution of x first sub-loops of metal element A and y second sub-loops of metal element B.

[0090] Although Figures 5A-5B Only one deposition cycle including metal precursor A and metal precursor B is shown. However, it should be understood that multiple deposition cycles can be performed to form a metal oxide semiconductor film of desired thickness, and sulfur-containing reactants can be used in any one or more of the multiple deposition cycles after depositing metal precursor A and before depositing metal precursor B to repair interface defects in the metal oxide semiconductor film. For example, repair can be performed in every deposition cycle, in a subset of deposition cycles, or only in the last deposition cycle, and so on.

[0091] The above method can be used to prepare metal oxide semiconductor thin films containing ternary metal oxides, wherein interface defects in the metal oxide semiconductor thin films are repaired in any one or more deposition cycles.

[0092] Figures 6A-6B This is a schematic flowchart of a method for preparing a metal oxide semiconductor thin film according to the fourth embodiment of this application.

[0093] In one embodiment, the metal precursor includes metal precursor A. Depositing the metal precursor using atomic layer deposition and oxidizing the metal precursor may include performing at least one first sub-loop. Performing a first sub-loop includes performing the following steps:

[0094] like Figure 6A As shown, in step 6A, a metal precursor A is deposited on the interface region 300 using atomic layer deposition (ALD) technology to ensure sufficient adsorption on the interface region 300. The circled A represents the metal precursor A. Depending on the different TFT structures, the interface region 300 can be the gate dielectric surface, the channel layer surface, or other suitable locations. The metal precursor A can be a conventional AOS precursor, such as triethylindium, trimethylgallium, diethylzinc, etc.

[0095] At step 6B, after one pulse of ALD of metal precursor A, an inert gas purging is performed to remove unreacted metal precursor A. The inert gas can be nitrogen or argon, etc.

[0096] In step 6C, an oxygen-containing reactant is introduced to react with the metal precursor A in an oxidation reaction. The hollow circles represent the oxygen-containing reactant. The oxygen-containing reactant can be a source of H₂O, O₃, etc.

[0097] In step 6D, an inert gas purging is performed to remove unreacted oxygen-containing reactants. The inert gas can be nitrogen or argon, etc.

[0098] After at least one first sub-loop has completed execution, the desired amount of metal precursor A can be deposited. To avoid redundancy, Figure 6A The schematic diagram of step 6D shows only one layer of metal precursor A and one layer of oxygen, but it can represent the completion of at least one first sub-cycle, that is, the completion of the deposition of multiple layers of metal precursor A and multiple layers of oxygen.

[0099] In one embodiment, repairing interface defects in metal oxide semiconductor thin films using sulfur-containing reactants may include performing the following steps:

[0100] Following step 6D, in step 6E, a sulfur-containing reactant S is introduced to passivate oxygen vacancies in the metal oxide formed after the oxidation of the metal precursor A. The circled S represents the sulfur-containing reactant S. The sulfur-containing reactant S can be inorganic gases such as H₂S and SO₂, or thiol-based organic compounds such as methanethiol, ethanethiol, and ethylenedithiol. The sulfur-containing reactant S can participate in interfacial reactions to locally repair interfacial defects in metal oxide semiconductor thin films.

[0101] At step 6F, an inert gas purging is performed to remove unreacted sulfur-containing reactants S. The inert gas can be nitrogen or argon, etc.

[0102] In one embodiment, the metal precursor further includes metal precursor B, wherein depositing the metal precursor using atomic layer deposition and oxidizing the metal precursor further includes executing at least one second sub-cycle after at least one first sub-cycle, wherein executing a second sub-cycle includes performing the following steps:

[0103] like Figure 6B As shown, after step 6F, at step 6G, a metal precursor B is deposited on the interface region 300 using atomic layer deposition (ALD) technology to ensure sufficient adsorption on the interface region 300. The circled B represents the metal precursor B. The metal precursor B can be a conventional AOS precursor, such as triethylindium, trimethylgallium, diethylzinc, etc.

[0104] At step 6H, after a pulse of ALD of the metal precursor B, an inert gas purging is performed to remove unreacted metal precursor B. The inert gas can be nitrogen or argon, etc.

[0105] In step 6I, an oxygen-containing reactant is introduced to react with the metal precursor B in an oxidation reaction. Hollow circles represent the oxygen-containing reactant. The oxygen-containing reactant can be a source of H2O, O3, etc. Due to the limitations of the oxidation reaction during deposition, oxygen vacancies may form in the metal oxide generated after the oxidation of the metal precursor B.

[0106] At step 6J, an inert gas purging is performed to remove unreacted oxygen-containing reactants. The inert gas can be nitrogen or argon, etc.

[0107] After at least one second sub-loop has completed execution, the desired amount of metal precursor B can be deposited. To avoid redundancy, Figure 6B The schematic diagram of step 6J shows only one layer of metal precursor B and one layer of oxygen, but it can represent the completion of at least one second sub-cycle, that is, the completion of the deposition of multiple layers of interleaved metal precursor B and multiple layers of oxygen. Therefore, Figure 6B The schematic diagram of step 6J in the diagram represents the completion of a deposition cycle of metal precursor A and metal precursor B.

[0108] The number of first and second sub-cycles in a deposition cycle depends on the composition of the metal oxide. For example, for a metal oxide A containing metal elements A and B in an elemental ratio of x:y... x B y O, a deposition cycle consists of x first sub-cycles of metal element A and y second sub-cycles of metal element B. Therefore, Figure 6B The schematic diagram of step 6J in the diagram can represent the completion of the execution of x first sub-loops of metal element A and y second sub-loops of metal element B.

[0109] In one embodiment, the following steps may also be performed in at least one of a plurality of deposition cycles:

[0110] Following step 6J, at step 6K, a sulfur-containing reactant is introduced to passivate oxygen vacancies in the metal oxide formed after oxidation of the metal precursor B. The circled S represents the sulfur-containing reactant S. The sulfur-containing reactant S can be inorganic gases such as H₂S and SO₂, or thiol-based organic compounds such as methanethiol, ethanethiol, and ethylenedithiol. The sulfur-containing reactant S can participate in interfacial reactions to locally repair interfacial defects in metal oxide semiconductor thin films.

[0111] At step 6L, an inert gas purging is performed to remove unreacted sulfur-containing reactants S. The inert gas can be nitrogen or argon, etc.

[0112] Although Figures 6A-6B Only one deposition cycle including metal precursor A and metal precursor B is shown; however, it should be understood that multiple deposition cycles can be performed to form a metal oxide semiconductor thin film of the desired thickness. At least one deposition cycle for passivating oxygen vacancies in the metal oxide formed after oxidation of metal precursor A can be the same deposition cycle as at least one deposition cycle for passivating oxygen vacancies in the metal oxide formed after oxidation of metal precursor B, or they can be different deposition cycles. For example, oxygen vacancies in the metal oxide formed after oxidation of metal precursor A can be passivated in the same deposition cycle as oxygen vacancies in the metal oxide formed after oxidation of metal precursor B; the same deposition cycle includes the last deposition cycle, a portion of deposition cycles, all deposition cycles, etc.; oxygen vacancies in the metal oxide formed after oxidation of metal precursor A can be passivated in a portion of deposition cycles, and oxygen vacancies in the metal oxide formed after oxidation of metal precursor B can be passivated in another portion of deposition cycles; these two portions of deposition cycles can be completely different or overlapping, etc.

[0113] The above method can be used to prepare metal oxide semiconductor thin films containing ternary metal oxides, wherein oxygen vacancies in the metal oxides generated after oxidation of metal precursor A and / or metal precursor B are passivated in any one or more deposition cycles.

[0114] While only a limited number of embodiments of methods for preparing metal oxide semiconductor thin films have been shown above, it should be understood that, for the same metal oxide, different embodiments can be freely combined as needed to utilize sulfur-containing reactants in deposition cycles to repair interface defects in metal oxide semiconductor thin films. Furthermore, although the above examples only pertain to binary and ternary metal oxides, similar thin film preparation methods can be applied to ternary and higher-order metal oxides.

[0115] The embodiments of this application, by precisely controlling the introduction and deposition cycle of reactants during the preparation of metal oxide semiconductor thin films, enable the in-situ introduction of sulfur elements at specific locations in the thin film during the growth process cycle, thereby achieving defect repair and interface optimization.

[0116] Figure 7 This is a block diagram of a system 700 for preparing metal oxide semiconductor thin films according to an embodiment of this application. The system 700 may include a deposition cycle execution unit 702 and an interface defect repair unit 704.

[0117] System 700 can be used to perform the following steps:

[0118] Using a deposition cycle execution unit 702, multiple deposition cycles are performed to form a metal oxide semiconductor thin film of desired thickness on an interface region. Each deposition cycle includes depositing a metal precursor using atomic layer deposition (ALD) and oxidizing the metal precursor.

[0119] Using the interface defect repair unit 704, in at least one of multiple deposition cycles, sulfur-containing reactants are used to repair interface defects in metal oxide semiconductor thin films.

[0120] This application also provides a method for fabricating thin-film transistors, the method comprising the following steps:

[0121] Preparation of substrates; and

[0122] A gate dielectric, a channel layer, a metal source / drain and a metal gate, and a sulfur-modified metal oxide semiconductor interface layer located between the gate dielectric and the channel layer are prepared on a substrate, wherein the sulfur-modified metal oxide semiconductor interface layer is prepared using the method described above for preparing metal oxide semiconductor thin films.

[0123] In one embodiment, the channel layer and the sulfur-modified metal-oxide-semiconductor interface layer can be prepared in different reaction chambers. By preparing them separately in different reaction chambers, processes using sulfur-containing reactants and processes not using sulfur-containing reactants can be strictly distinguished, avoiding sulfur contamination of the channel layer deposition. Alternatively, the channel layer and the sulfur-modified metal-oxide-semiconductor interface layer can be prepared in the same reaction chamber. Preparing them in the same reaction chamber simplifies the process steps and saves costs.

[0124] In one embodiment, atomic layer deposition (ALD) technology can be used to prepare the channel layer.

[0125] The embodiments of this application can achieve in-situ precise repair of interface defects by controlling the introduction of sulfur-containing reactants, thereby significantly improving the structural stability and carrier mobility of AOS films.

[0126] It should be understood that the above description is illustrative and not restrictive. For example, the above embodiments (and / or aspects thereof) can be used in combination with each other. Furthermore, many modifications can be made to adapt particular conditions or materials to the teachings of the various embodiments of the invention without departing from the scope of the invention. While the dimensions and types of materials described herein are used to define parameters of the various embodiments of the invention, the embodiments are not intended to be restrictive but are exemplary. Many other embodiments will become apparent to those skilled in the art upon reading the above description. Therefore, the scope of the various embodiments of the invention should be determined by reference to the appended claims and the full scope of their equivalents.

Claims

1. A method for preparing metal oxide semiconductor thin films, characterized in that, The method includes: Multiple deposition cycles are performed to form a metal oxide semiconductor thin film of desired thickness on an interface region, wherein performing one of the deposition cycles includes depositing a metal precursor using atomic layer deposition and oxidizing the metal precursor; and In at least one of the plurality of deposition cycles, sulfur-containing reactants are used to repair interface defects in the metal oxide semiconductor thin film.

2. The method as described in claim 1, characterized in that, The metal precursor includes a first precursor, wherein depositing the metal precursor using atomic layer deposition and oxidizing the metal precursor includes performing the following steps: (1) The first precursor is deposited on the interface region using atomic layer deposition technology; (2) Perform an inert gas purging to remove unreacted first precursor; (3) Introducing an oxygen-containing reactant to oxidize the first precursor; and (4) Perform inert gas purging to remove unreacted oxygen-containing reactants.

3. The method as described in claim 2, characterized in that, Repairing interface defects in the metal oxide semiconductor thin film using sulfur-containing reactants includes performing the following steps: After step (4), a sulfur-containing reactant is introduced to passivate the oxygen vacancies in the metal oxide generated after the oxidation of the first precursor; as well as Perform an inert gas purging to remove unreacted sulfur-containing reactants.

4. The method as described in claim 1, characterized in that, The metal precursor includes a first precursor, wherein depositing the metal precursor using atomic layer deposition and oxidizing the metal precursor includes executing at least one first sub-cycle, and executing one first sub-cycle includes performing the following steps: (A1) The first precursor is deposited on the interface region using atomic layer deposition technology; (A2) Perform an inert gas purging to remove unreacted first precursor; (A3) Introducing an oxygen-containing reactant to oxidize the first precursor; and (A4) Perform an inert gas purging to remove unreacted oxygen-containing reactants.

5. The method as described in claim 4, characterized in that, The metal precursor further includes a second precursor, wherein depositing the metal precursor using atomic layer deposition and oxidizing the metal precursor further includes executing at least one second sub-cycle after the at least one first sub-cycle, and executing a second sub-cycle includes performing the following steps: (B1) After step (A4), the second precursor is deposited on the interface region using atomic layer deposition technology; (B2) Perform an inert gas purging to remove unreacted second precursor; (B3) Introducing an oxygen-containing reactant to oxidize the second precursor; and (B4) Perform an inert gas purging to remove unreacted oxygen-containing reactants.

6. The method as described in claim 5, characterized in that, Repairing interface defects in the metal oxide semiconductor thin film using sulfur-containing reactants includes performing the following steps: After step (B4), a sulfur-containing reactant is introduced to passivate the oxygen vacancies in the metal oxide generated after the oxidation of the second precursor; as well as Perform an inert gas purging to remove unreacted sulfur-containing reactants.

7. The method as described in claim 5, characterized in that, Repairing interface defects in the metal oxide semiconductor thin film using sulfur-containing reactants includes performing the following steps: After step (A4) and before step (B1), a sulfur-containing reactant is introduced to passivate the oxygen vacancies in the metal oxide generated after the oxidation of the first precursor; as well as Perform an inert gas purging to remove unreacted sulfur-containing reactants.

8. The method as described in claim 7, characterized in that, The method further includes: Perform the following steps in at least one of the plurality of deposition cycles: Following step (B4), a sulfur-containing reactant is introduced to passivate oxygen vacancies in the metal oxide formed after oxidation of the second precursor; and Perform an inert gas purging to remove unreacted sulfur-containing reactants.

9. The method as described in claim 1, characterized in that, The metal oxide semiconductor thin film includes one of the following: binary metal oxide, ternary metal oxide, or metal oxide with more than three elements.

10. The method as described in claim 1, characterized in that, The sulfur-containing reactants are sulfur-containing inorganic gases or thiol-based organic compounds.

11. The method as described in claim 1, characterized in that, The desired thickness is no more than 1 nm.

12. A thin-film transistor, characterized in that, include: Substrate; Gate dielectric; Channel layer; Metal source / drain and metal gate; as well as A sulfur-modified metal oxide semiconductor interface layer is located between the gate dielectric and the channel layer, wherein the sulfur-modified metal oxide semiconductor interface layer is prepared by using the method described in any one of claims 1 to 11.

13. The thin-film transistor as claimed in claim 12, characterized in that, The thin-film transistor can be a top-gate structure, a bottom-gate structure, a ring gate structure, or a vertical ring channel structure.

14. A method for fabricating thin-film transistors, characterized in that, The method includes: Preparation of substrates; and A gate dielectric, a channel layer, a metal source / drain and a metal gate, and a sulfur-modified metal oxide semiconductor interface layer located between the gate dielectric and the channel layer are prepared on the substrate, wherein the sulfur-modified metal oxide semiconductor interface layer is prepared using the method described in any one of claims 1 to 11.

15. The method as described in claim 14, characterized in that, The channel layer and the sulfur-modified metal oxide semiconductor interface layer are prepared in different reaction chambers.

16. A system for preparing metal oxide semiconductor thin films, characterized in that, The system includes a deposition cycle execution unit and an interface defect repair unit, and is used to perform the following steps: Using a deposition cycle execution unit, multiple deposition cycles are performed to form a metal oxide semiconductor thin film of desired thickness on an interface region, wherein performing one of the deposition cycles includes depositing a metal precursor using atomic layer deposition (ALD) and oxidizing the metal precursor; and Using an interface defect repair unit, in at least one of the plurality of deposition cycles, sulfur-containing reactants are used to repair interface defects in the metal oxide semiconductor thin film.

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