Preparation method of hardness gradient film, hardness gradient film and flexible conductive structure

Abstract

The invention relates to the technical field of thin film preparation, and particularly discloses a preparation method of a hardness gradient thin film, the hardness gradient thin film and a flexible conductive structure. According to the method, continuous gradient transition of the hardness of the thin film from a soft interval to a hard interval is realized by dynamically regulating and controlling the flow ratio of the soft component gas to the hard component gas, and the method has the advantages of smooth transition, high preparation efficiency and the like. The hardness gradient thin film is arranged between the flexible substrate and the ITO thin film, so that the problem of interface stress mismatch between the flexible substrate and the ITO thin film can be effectively relieved, and the adhesive force of the ITO thin film on the surface of the flexible substrate is remarkably improved; meanwhile, the hardness gradient thin film has excellent water and oxygen barrier performance, permeation interference of water and oxygen can be effectively isolated in the ITO thin film deposition process, the sheet resistance of the ITO thin film is reduced, and the technical problems that in the prior art, the mechanical performance matching performance between the flexible substrate and the ITO thin film is poor, and the performance of the ITO thin film is degraded due to water and oxygen crosstalk are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thin film preparation, in particular to a preparation method of a hardness gradient thin film, the hardness gradient thin film and a flexible conductive structure. BACKGROUND

[0002] In the fields of flexible electronics, display devices, touch sensing, etc., the flexible conductive structure formed by the flexible substrate represented by PET (polyethylene terephthalate) and the ITO (indium tin oxide) thin film becomes a core key component due to the synergistic demand of its light transmission and conductivity.

[0003] However, the ITO thin film is essentially a hard and brittle ceramic material, and there is a huge difference of two orders of magnitude between its elastic modulus and the PET substrate. This significant difference in mechanical properties makes the interface between the ITO thin film and the flexible substrate of the flexible conductive structure prone to stress concentration during service, which in turn causes the ITO thin film to appear micro-cracks, peeling and even falling off, etc. failure forms, which seriously affects the reliability of the long-term use of the flexible conductive structure. At the same time, the PET substrate will continuously release moisture and residual organic volatile substances under the heating conditions in the process environment of ITO thin film preparation, such as vacuum coating, sputtering deposition, etc. Moisture and organic volatile substances will directly mix into the ITO thin film lattice in the growth stage, on the one hand, destroy its crystal structure, leading to a decrease in film crystallinity and an increase in defect density; on the other hand, it will hinder the migration and transmission of carriers, eventually causing the sheet resistance of the ITO thin film to increase significantly, and even unable to meet the performance requirements of the conductive layer of the flexible electronic device.

[0004] At present, the various preparation methods disclosed in the art are difficult to simultaneously solve the above two technical problems in a single process flow. Therefore, there is an urgent need for a technical solution that can simultaneously solve the mechanical mismatch between the flexible substrate and the ITO thin film, and the performance defects of the ITO thin film caused by water and oxygen interference. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a preparation method of a hardness gradient thin film, the hardness gradient thin film and a flexible conductive structure, which are used to solve the technical problems of poor mechanical performance matching between the flexible substrate and the ITO thin film, and the electrical performance attenuation of the ITO thin film caused by water and oxygen interference in the prior art.

[0006] To achieve the above technical purpose, the present application provides a preparation method of a hardness gradient thin film, comprising the following steps:

[0007] Using a mixed gas as raw material, a thin film deposition reaction is carried out on the surface of the flexible substrate by PECVD process to obtain a hardness gradient thin film;

[0008] The mixed gas comprises a soft component gas for forming a soft phase and a hard component gas for forming a hard phase; under the condition that the total flow rate of the mixed gas is constant, the flow rate of the soft component gas is reduced and the flow rate of the hard component gas is increased as the deposition reaction proceeds.

[0009] Further, in the mixed gas, the volume percentage of the soft component gas is 0% to 100% by volume, and the balance is the hard component gas.

[0010] Further, the flow rate control mode of the soft component gas and the hard component gas comprises any one of the following modes:

[0011] Mode one: the deposition reaction process comprises at least one transition deposition period; in the transition deposition period, the flow rate of the soft component gas is reduced at a constant rate, and the flow rate of the hard component gas is increased at a constant rate;

[0012] Mode two: the deposition reaction process comprises a plurality of continuous stable deposition periods; in the stable deposition period, the flow rates of the soft component gas and the hard component gas remain constant, and the flow rate of the soft component gas in the later stable deposition period is lower than that in the former stable deposition period;

[0013] Mode three: the deposition reaction process comprises a plurality of stable deposition periods and transition deposition periods; in the stable deposition period, the flow rates of the soft component gas and the hard component gas remain constant; in the transition deposition period, the flow rate of the soft component gas is reduced at a constant rate; and a transition deposition period is arranged between any adjacent stable deposition periods.

[0014] Further, in the transition deposition period, the flow rate reduction rate of the soft component gas and the flow rate increase rate of the hard component gas are independently selected from 0.05 sccm / min to 100 sccm / min; and in the stable deposition period, the flow rate difference of the soft component gas between any adjacent stable deposition periods is 0.05 sccm to 100 sccm.

[0015] Further, the soft component gas comprises at least one of methane, ethane, propane, acetylene, benzene, toluene, hexamethyldisiloxane, and tetramethylsilane; and / or the hard component gas comprises at least one of silane, disilane, silicon tetrachloride, tetraethoxysilane, nitrous oxide, oxygen, carbon dioxide, ammonia, and nitrogen.

[0016] The application provides a hardness gradient film, which comprises a transition layer arranged between a flexible substrate and an ITO film; the hardness of the transition layer increases in the direction from the flexible substrate to the ITO film.

[0017] The transition layer is deposited by a PECVD process using a mixed gas, wherein the mixed gas comprises a soft component gas for forming a soft phase and a hard component gas for forming a hard phase.

[0018] Further, the transition layer comprises a plurality of gradient layers and a plurality of uniform layers; hardness of the gradient layers increases in a direction from the flexible substrate to the ITO film, and hardness of the uniform layers is uniform, and the gradient layers are arranged between adjacent uniform layers.

[0019] Further, the transition layer comprises a plurality of gradient layers and a plurality of uniform layers; hardness of the gradient layers increases in a direction from the flexible substrate to the ITO film, and hardness of the uniform layers is uniform, and the gradient layers are arranged between adjacent uniform layers.

[0020] Further, the transition layer comprises a plurality of gradient layers and a plurality of uniform layers; hardness of the gradient layers increases in a direction from the flexible substrate to the ITO film, and hardness of the uniform layers is uniform, and the gradient layers are arranged between adjacent uniform layers.

[0021] The application provides a flexible conductive structure for preparing an electrical component, comprising a flexible substrate, a hardness gradient film and an ITO film arranged in sequence.

[0022] In summary, the application provides a preparation method of a hardness gradient film. The method uses a mixed gas as raw material, and performs a thin film deposition reaction on the surface of a flexible substrate by a PECVD process to obtain a hardness gradient film. The mixed gas comprises a soft component gas for forming a soft phase and a hard component gas for forming a hard phase. Under the condition that the total flow of the mixed gas is constant, the flow of the soft component gas is reduced and the flow of the hard component gas is increased as the deposition reaction proceeds. That is, the method dynamically adjusts the flow ratio of the soft component gas and the hard component gas to realize a continuous gradient transition of the film hardness from the soft zone to the hard zone, and has the advantages of smooth transition, high preparation efficiency, etc.

[0023] The application provides a hardness gradient film. The hardness gradient film comprises a transition layer arranged between a flexible substrate and an ITO film, and the hardness of the transition layer increases in a direction from the flexible substrate to the ITO film. The hardness gradient film provided by the application is arranged between the flexible substrate and the ITO film, which can effectively relieve the interface stress mismatching problem between the flexible substrate and the ITO film, significantly improve the adhesion and the cyclic bending stability of the ITO film on the surface of the flexible substrate. At the same time, the hardness gradient film has excellent water vapor and gas barrier properties, which can effectively isolate the penetration of external water and oxygen during the subsequent ITO film deposition process, optimize the crystallization kinetics process of the ITO film, reduce the internal defect density of the film, and finally realize the synergistic optimization of low sheet resistance and high conductivity of the ITO film.

[0024] Compared with the prior art, the hardness gradient film provided by the application successfully realizes the smooth transition of mechanical properties between the flexible substrate and the ITO film, effectively solves the stress mismatch problem between the ITO film and the substrate in the traditional structure. At the same time, as a dense gas barrier layer, the hardness gradient film effectively isolates the impurity gas released by the flexible substrate, and optimizes the preparation environment of the ITO film. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0026] Figure 1 The flow control mode schematic diagram of the soft component gas and the hard component gas provided by the embodiment of the present application is shown in the figure.

[0027] Figure 2 The flow control mode schematic diagram of the soft component gas and the hard component gas provided by the embodiment of the present application is shown in the figure.

[0028] Figure 3 The hardness gradient film hardness changes with the thickness of the schematic diagram provided by the embodiment of the present application is shown in the figure.

[0029] Figure 4 The hardness gradient film hardness changes with the thickness of the schematic diagram provided by the embodiment of the present application is shown in the figure.

[0030] Figure 5 The structure schematic diagram of the hardness gradient film provided by the embodiment 1 of the present application is shown in the figure. DETAILED DESCRIPTION

[0031] The technical solutions of the embodiments of the present application will be described in detail below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of the present application.

[0032] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0033] Unless otherwise expressly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0034] Among them, all raw materials of the present application have no special restriction on the source, which can be purchased in the market or prepared according to the conventional method familiar to those skilled in the art.

[0035] The embodiment of the present application provides a preparation method of a hardness gradient film, comprising the following steps:

[0036] The hardness gradient film is obtained by using mixed gas as raw material and adopting PECVD process to carry out thin film deposition reaction on the surface of flexible substrate.

[0037] Among them, the mixed gas includes soft component gas for forming soft phase and hard component gas for forming hard phase; under the condition that the total flow of mixed gas is constant, the flow of soft component gas is reduced and the flow of hard component gas is increased with the progress of deposition reaction.

[0038] It should be noted that the above flow control strategy realizes the smooth transition of mechanical properties between the flexible substrate and the ITO film, and specifically realizes the continuous gradient adjustment of hardness from 0.5GPa to 4.0GPa, effectively buffers the stress difference between the ITO film and the flexible substrate, solves the problem of easy cracking and falling of ITO film existing in traditional single hardness film, and significantly improves the mechanical stability of flexible conductive structure (flexible substrate and ITO film). In addition, the hardness gradient film prepared by the present application also has a dense microstructure, which can be used as an efficient gas barrier layer, which can effectively isolate the water vapor or impurity gas released by the flexible substrate (such as PET substrate) during subsequent processing or use, provide a pure and stable interface environment for the deposition of ITO film, and thus improve the electrical performance of ITO film.

[0039] In some embodiments, the volume percentage of the soft component gas in the mixed gas is 0% to 100%, and the balance is the hard component gas.

[0040] In some preferred embodiments, when the deposition reaction process includes multiple deposition periods, the soft component gas dominates (volume ratio ≥ 50%) or is pure soft component gas in the mixed gas at the initial stage of deposition; the hard component gas dominates (volume ratio ≥ 50%) or is pure hard component gas in the mixed gas at the end of deposition, and by controlling the gas flow ratio at different stages, a continuous increasing gradient distribution of the hardness gradient film can be ensured from the flexible substrate to the ITO film.

[0041] In some specific embodiments, the volume percentage of the soft component gas in the mixed gas at the initial stage of deposition is 80% to 95%, and the balance is the hard component gas. The parameter ratio provided in this embodiment can form a hardness gradient film with a lower initial hardness on the side close to the flexible substrate, and the hardness of the hardness gradient film is close to the hardness level of the flexible substrate, which can effectively reduce the interfacial stress between the ITO film and the flexible substrate.

[0042] In some embodiments, the flow control mode of the soft component gas and the hard component gas includes any one of the following modes:

[0043] Mode one: the deposition reaction process includes at least one transition deposition period; during the transition deposition period, the flow of the soft component gas decreases at a constant rate, and the flow of the hard component gas increases at a constant rate;

[0044] Mode two: the deposition reaction process includes multiple continuous stable deposition periods; during the stable deposition period, the flow of the soft component gas and the hard component gas remains constant, and the flow of the soft component gas in the later stable deposition period is lower than that in the former stable deposition period;

[0045] Mode three: the deposition reaction process includes multiple stable deposition periods and transition deposition periods; during the stable deposition period, the flow of the soft component gas and the hard component gas remains constant; during the transition deposition period, the flow of the soft component gas decreases at a constant rate; a transition deposition period is arranged between any adjacent stable deposition periods.

[0046] In some specific embodiments, the deposition reaction process includes three stable deposition periods and two transition deposition periods, and a transition deposition period is arranged between any adjacent stable deposition periods. For example, Figure 1As shown, when methane is used as the soft component gas and the mixed gas of silane and nitrous oxide is used as the hard component gas, the control mode is set as follows: the flow control of methane is divided into five stages, in turn, a constant flow stage-a flow decreasing at a constant rate stage-a constant flow stage-a flow increasing at a constant rate stage-a constant flow stage; the flow control of the mixed gas of silane and nitrous oxide corresponds to the five stages in turn, a constant flow stage-a flow increasing at a constant rate stage-a constant flow stage-a flow increasing at a constant rate stage-a constant flow stage, through the coordinated control of the flow of the soft component gas and the hard component gas, the smooth transition of the film hardness is realized.

[0047] In some embodiments, the deposition reaction process includes two stable deposition periods and a transition deposition period; the transition deposition period is arranged between the two stable deposition periods. Figure 2 As shown, when methane is used as the soft component gas and the mixed gas of silane and nitrous oxide is used as the hard component gas, the control mode is set as follows: the flow control of methane is divided into three stages, in turn, a constant flow stage-a flow decreasing at a constant rate stage-a constant flow stage; the flow control of the mixed gas of silane and nitrous oxide corresponds to the three stages in turn, a constant flow stage-a flow increasing at a constant rate stage-a constant flow stage, realizing the smooth transition of the film hardness from soft to hard.

[0048] In some embodiments, in the transition deposition period, the flow decreasing rate of the soft component gas and the flow increasing rate of the hard component gas are independently selected from 0.05 sccm / min to 100 sccm / min; in the stable deposition period, the flow difference of the soft component gas between any adjacent stable deposition periods is 0.05 sccm to 100 sccm. In some embodiments, the soft component gas includes at least one of methane, ethane, propane, acetylene, benzene, toluene, hexamethyldisiloxane, and tetramethylsilane; and / or, the hard component gas includes at least one of silane, disilane, silicon tetrachloride, tetraethoxysilane, nitrous oxide, oxygen, carbon dioxide, ammonia, and nitrogen.

[0049] Embodiments of the present application provide a hardness gradient film, which includes a transition layer arranged between a flexible substrate and an ITO film; the hardness of the transition layer increases along the direction from the flexible substrate to the ITO film;

[0050] The transition layer is deposited by a PECVD process using a mixed gas, which includes a soft component gas for forming a soft phase and a hard component gas for forming a hard phase.

[0051] In some embodiments, the transition layer includes a plurality of gradient layers and a plurality of uniform layers; the hardness of the gradient layers increases along the direction from the flexible substrate to the ITO film, the hardness of the uniform layers is uniform, and the gradient layers are arranged between adjacent uniform layers.

[0052] In some embodiments, a soft layer and a hard layer are further included; the soft layer is disposed between the flexible substrate and the transition layer, and the hard layer is disposed between the transition layer and the ITO film, and the hardness of the soft layer, the transition layer and the hard layer increases sequentially along the direction from the flexible substrate to the ITO film.

[0053] In some specific embodiments, the hardness gradient film includes a soft layer, a transition layer, and a hard layer sequentially disposed therefrom; wherein, the transition layer consists of two gradient layers and a homogenizing layer, with the homogenizing layer sandwiched between the two gradient layers, forming a transition structure of "gradient layer-homogenizing layer-gradient layer", the specific hardness change of which is as follows: Figure 3 As shown.

[0054] In some specific embodiments, the hardness gradient film includes a soft layer, a transition layer, and a hard layer sequentially disposed; wherein, the transition layer is a single continuous gradient layer, which achieves a smooth transition of mechanical properties between the soft layer and the hard layer, and its specific hardness change is as follows: Figure 4 As shown in Table 1, the main performance parameters of the soft layer, transition layer, and hard layer in this embodiment are as follows.

[0055] Table 1. Main performance characteristics of the soft layer, transition layer and hard layer

[0056]

[0057] In some embodiments, the system further includes a soft layer and a hard layer; the hardness of the soft layer is 0.3 GPa to 0.7 GPa, the hardness of the transition layer is 0.3 GPa to 4.5 GPa, and the hardness of the hard layer is 3.5 GPa to 4.5 GPa.

[0058] This application provides a flexible conductive structure for fabricating electrical components, comprising a flexible substrate, a hardness gradient film, and an ITO film arranged sequentially.

[0059] The applicant further provides the following specific embodiments to describe the present invention. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0060] Example 1

[0061] This embodiment provides a method for preparing a hardness gradient thin film, including the following steps:

[0062] Step S1, Equipment Debugging and Substrate Pretreatment: The deposition equipment used in this experiment is a parallel plate PECVD system, and the substrate is a flexible PET film. The substrate is placed in the reaction chamber of the parallel plate PECVD system, and a vacuum operation is performed on the reaction chamber until the vacuum degree inside the chamber is 5×10⁻⁶. −4Pa; and the surface temperature of the PET flexible film is 80°C by adjusting the temperature in the cavity;

[0063] Step S2, depositing the hardness gradient film on the substrate surface in stages: set the soft component gas as methane, and the hard component gas as silane and nitrous oxide; set the total gas flow constant at 50 sccm, the working gas pressure in the reaction cavity at 10 Pa, the radio frequency power at 250 W, and the total deposition time at 25 minutes; in the deposition process of this embodiment, a plurality of deposition periods are included, and the specific changes of the gas flow in each period are as follows:

[0064] First stage, depositing the soft layer: between 0 and 5 minutes, the gas flow of methane is constant at 45 sccm, and the gas flow of silane is constant at 5 sccm;

[0065] Second stage, depositing the transition layer: between 5 and 20 minutes, the methane decreases linearly at a rate of-1.5 sccm / min (from 45 sccm to 22.5 sccm); the silane increases linearly at a rate of 0.5 sccm / min (from 5 sccm to 12.5 sccm); and the nitrous oxide increases linearly at a rate of 1 sccm / min (from 0 sccm to 15 sccm);

[0066] Third stage, depositing the hard layer: between 20 and 25 minutes: the gas flow of methane is constant at 22.5 sccm, the gas flow of silane is constant at 12.5 sccm, and the gas flow of nitrous oxide is constant at 15 sccm; the deposition is completed, and the hardness gradient film is obtained.

[0067] In this embodiment, the hardness gradient film is arranged on one side of the substrate, and is arranged in the order of the soft layer, the transition layer, and the hard layer from the substrate to the side away from the substrate, as shown in Figure 5 ; the thickness of the hardness gradient film is about 200 nm, and the hardness thereof is smoothly transitioned from 0.5 GPa to 4.0 GPa. After depositing an ITO film with a thickness of 120 nm on the hardness gradient film, a flexible conductive structure is formed, and the square resistance of the flexible conductive structure is 18 Ω / sq.

[0068] Comparative Example 1

[0069] This comparative example provides a method for preparing a hardness gradient film, including the following steps:

[0070] Step S1, equipment debugging and substrate pretreatment: the deposition equipment used in this experiment is a parallel plate PECVD system, and the substrate is a PET flexible film; the substrate is placed in the reaction cavity of the parallel plate PECVD system, and the reaction cavity is subjected to vacuumizing operation until the vacuum degree inside the cavity is 5x10-4Pa; and the surface temperature of the PET flexible film is 80°C by adjusting the temperature in the cavity;

[0071] Step S2, depositing a hardness gradient film on the substrate surface in stages: set the soft component gas as methane, the hard component gas as silane and nitrous oxide; set the total gas flow rate as 50 sccm, the working gas pressure in the reaction cavity as 10 Pa, the radio frequency power as 250 W, and the total deposition time as 25 minutes; during the deposition process, the specific changes of the gas flow rate are as follows:

[0072] First stage, depositing a soft layer: between 0 and 10 minutes, the gas flow rate of methane is constant at 50 sccm;

[0073] Second stage, depositing a hard layer: between 10 and 25 minutes: the gas flow rate of silane is constant at 25 sccm, and the gas flow rate of nitrous oxide is constant at 25 sccm; after the deposition is completed, a hardness gradient film is obtained.

[0074] In the present comparative example, the hardness gradient film is arranged on one side of the substrate, and is arranged in the order of a soft layer and a hard layer from the substrate to the side away from the substrate; the thickness of the hardness gradient film is about 200 nm. After depositing an ITO film with a thickness of 120 nm on the hardness gradient film, a flexible conductive structure is formed, the square resistance of the ITO film in the flexible conductive structure is 30 Ω / sq; and in the bending test, the ITO film has a small crack.

[0075] Comparative Example 2

[0076] The present comparative example provides a preparation method of a flexible conductive structure, comprising the following steps:

[0077] Step S1, equipment debugging and substrate pretreatment: the deposition equipment used in the present experiment is a parallel plate type PECVD system, and the substrate is a PET flexible film; the substrate is placed in the reaction cavity of the parallel plate type PECVD system, the reaction cavity is subjected to vacuumizing operation, and the vacuum degree inside the cavity is 5x10 −4 Pa; and the surface temperature of the PET flexible film is adjusted to 80℃ by adjusting the temperature in the cavity;

[0078] Step S2, depositing an ITO film on the substrate surface, the thickness of the ITO film is 120 nm, and a flexible conductive structure is obtained. The square resistance of the ITO film is 35 Ω / sq, and in the bending test, the ITO film of the flexible conductive structure has obvious cracking and peeling.

[0079] In order to further characterize the influence of the preparation method of the hardness gradient film on the hardness gradient film and the flexible conductive structure formed thereby, the present application carries out characterization tests from four dimensions of stress characteristics, gas barrier performance, ITO film square resistance (ASTM F43-20) and ITO film adhesion (HG / T 5299-2018), and the test results are summarized in Table 2.

[0080] Table 2. Performance characterization of flexible conductive structure in bending test

[0081]

[0082] From the performance comparison data in Table 2, it can be clearly seen that the hardness gradient film prepared based on the PECVD process provided by Example 1 realizes the "smooth connection" of the mechanical properties between the flexible substrate and the ITO film, and the stress relief effect is optimal; in the bending test, the ITO film has excellent adhesion, no cracks, and no peeling phenomenon, completely solving the problem of film cracking and peeling caused by interface stress concentration in the traditional structure (such as Comparative Examples 1-2). From the perspective of electrical performance guarantee, the hardness gradient film structure of Example 1 has excellent compactness and has efficient gas barrier function: it can effectively block the moisture and organic volatile substances released by the PET substrate in the ITO preparation process, and also provides a pure vacuum environment for the growth of the ITO film, avoiding the mixing of impurities into the ITO lattice to destroy the crystal structure. This advantage is directly reflected in the sheet resistance data: the sheet resistance of the flexible conductive structure of Example 1 is only 18 Ω / sq, which is much better than that of the comparative examples, which fully proves that the hardness gradient film can greatly improve the crystalline quality and carrier transport efficiency of the ITO film.

[0083] In summary, Example 1 fundamentally and simultaneously solves the two major problems of "mechanical reliability deficiency" and "electrical performance degradation" of ITO film in the field of flexible electronics, and realizes the synergistic optimization of the mechanical and electrical properties of the flexible conductive structure.

[0084] The above is only a preferred embodiment of the present application and does not limit the present application. Although the present application has been described in detail with reference to the examples, those skilled in the art can still modify the technical solutions described in the examples or make equivalent replacements to some technical features, but any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a hardness gradient thin film, characterized in that, Includes the following steps: Using a mixed gas as raw material, a thin film deposition reaction was carried out on the surface of a flexible substrate using the PECVD process to obtain a hardness gradient film. The mixed gas includes a soft component gas for forming a soft phase and a hard component gas for forming a hard phase; under the condition that the total flow rate of the mixed gas is constant, as the deposition reaction proceeds, the flow rate of the soft component gas is reduced and the flow rate of the hard component gas is increased.

2. The method for preparing a hardness gradient thin film according to claim 1, characterized in that, In the mixed gas, the soft component gas accounts for 0% to 100% by volume, and the remainder is the hard component gas.

3. The method for preparing a hardness gradient thin film according to claim 1, characterized in that, The flow control modes for the soft component gas and the hard component gas include any of the following: Mode 1: The deposition reaction process includes at least one transition deposition period; during the transition deposition period, the flow rate of the soft component gas decreases at a constant rate, and the flow rate of the hard component gas increases at a constant rate. Mode 2: The depositional reaction process includes multiple consecutive stable depositional periods; During the stable deposition period, the flow rates of soft component gas and hard component gas remain constant, and the flow rate of soft component gas in the later stable deposition period is lower than that in the earlier stable deposition period. Mode 3: The deposition reaction process includes multiple stable deposition periods and transitional deposition periods; wherein, during the stable deposition periods, the flow rates of soft component gas and hard component gas remain constant; during the transitional deposition periods, the flow rate of soft component gas decreases at a constant rate; and a transitional deposition period is set between any two adjacent stable deposition periods.

4. The method for preparing a hardness gradient thin film according to claim 3, characterized in that: During the transition deposition period, the rate of decrease in the flow rate of the soft component gas and the rate of increase in the flow rate of the hard component gas are both independently selected from 0.05 sccm / min to 100 sccm / min; Within the stable deposition period, the difference in soft component gas flow rate between any two adjacent stable deposition periods is 0.05 sccm to 100 sccm.

5. The method for preparing a hardness gradient thin film according to any one of claims 1 to 4, characterized in that, The soft component gas includes at least one of methane, ethane, propane, acetylene, benzene, toluene, hexamethyldisiloxane, and tetramethylsilane; And / or, the hard component gas includes at least one of silane, disilane, silicon tetrachloride, tetraethoxysilane, nitrous oxide, oxygen, carbon dioxide, ammonia, and nitrogen.

6. A hardness gradient thin film, characterized in that, The hardness gradient film includes a transition layer disposed between the flexible substrate and the ITO film; the hardness of the transition layer increases along the direction from the flexible substrate to the ITO film. The transition layer is prepared by a PECVD process using a mixed gas, which includes a soft component gas for forming a soft phase and a hard component gas for forming a hard phase.

7. The hardness gradient film according to claim 6, characterized in that, The transition layer includes multiple gradient layers and multiple homogenization layers; the hardness of the gradient layers increases along the direction from the flexible substrate to the ITO film, the hardness of the homogenization layers is uniform, and the gradient layers are disposed between adjacent homogenization layers.

8. The hardness gradient film according to any one of claims 6 to 7, characterized in that, It also includes a soft layer and a hard layer; the soft layer is disposed between the flexible substrate and the transition layer, and the hard layer is disposed between the transition layer and the ITO film, and the hardness of the soft layer, the transition layer and the hard layer increases sequentially along the direction from the flexible substrate to the ITO film.

9. The hardness gradient film according to any one of claims 8, characterized in that, The hardness of the soft layer is 0.3 GPa to 0.7 GPa, the hardness of the transition layer is 0.3 GPa to 4.5 GPa, and the hardness of the hard layer is 3.5 GPa to 4.5 GPa.

10. A flexible conductive structure for fabricating electrical components, characterized in that, It includes a flexible substrate, a hardness gradient film, and an ITO film arranged sequentially; the hardness gradient film is a hardness gradient film obtained by the preparation method according to any one of claims 1 to 5 or a hardness gradient film according to any one of claims 6 to 9.

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