Atomic layer infiltration deposition composite film with strong Al-O bonding and preparation method thereof

Abstract

The present invention discloses an atomic layer infiltration deposition composite film with strong Al-O bonding, comprising an organic layer, an organic-inorganic hybrid layer, and an inorganic layer, wherein the organic layer is PET, PEN, or PI, the inorganic layer is aluminum oxide, titanium oxide, or zirconium oxide, and the organic-inorganic hybrid layer is a composite layer formed by the organic layer and the inorganic layer. The present invention provides a method for improving the adhesion ability of an inorganic coating material inside and on the surface of an organic substrate, the method being used to form a compact organic-inorganic hybrid layer with Al-O bonding inside a flexible substrate, and forming an inorganic thin film layer with Al-O bonding on the surface of the flexible substrate. The present invention relates to corona treatment of a flexible substrate to thereby improve the adhesion and bonding ability of an inorganic coating on the surface and inside of a flexible substrate, and is particularly suitable for packaging application scenarios of modified alumina composite films.

Description

Technical Field

[0001] The present invention belongs to the technical field of thin film materials, and in particular relates to an atomic layer infiltration deposition composite film based on strong Al-O bonding to improve the adhesion of aluminum oxide on the surface and inside of a flexible substrate, and a preparation method thereof. Background Art

[0002] Inorganic barrier films are typically deposited using methods such as evaporation, sputtering, chemical vapor deposition (CVD), and atomic layer deposition (ALD). Among these methods, ALD is one of the most promising technologies for industrial-scale deposition of high-quality barrier films due to its low preparation temperature and good uniformity. Thin Al2O3 coatings grown by atomic layer deposition (ALD) can serve as high-quality, non-porous barrier films. Atomic layer deposition allows the production of pinhole-free, highly uniform, and conformal Al2O3 films at low temperatures (0-100°C) and with atomic-scale thickness control, meeting many of the requirements of passivation layers as they provide high gas barrier properties, good thermal and mechanical stability, high optical transmittance, and good adhesion to a variety of substrates.

[0003] ALD is based on a continuous, self-limiting chemical reaction. Due to its self-limiting nature, the composition and thickness of the deposited film can be precisely controlled at the atomic scale. Furthermore, ALD is capable of depositing highly uniform films in high-aspect-ratio trenches or pores, which is difficult to achieve with traditional physical vapor deposition. ALD precursors are also crucial; they are typically metal-organic compounds, and their volatility, thermal stability, and self-limiting reactivity can significantly influence the growth behavior of ALD films. Thin films deposited by atomic layer deposition grow only one atomic layer per reaction, allowing for precise control of film thickness. Compared to traditional chemical vapor deposition (CVD) reactions, ALD requires relatively low reaction temperatures, making it a promising candidate for modifying the surfaces of certain materials that are sensitive to high temperatures. Furthermore, the ALD process alternates the introduction of precursors into the reaction chamber, preventing simultaneous presence of precursors within the chamber and avoiding chained CVD reactions. ALD technology relies heavily on the surface chemistry involved, which can significantly influence the properties of the deposited film, such as film thickness, morphology, conformality, and composition. Therefore, a comprehensive understanding of surface chemistry and its associated mechanisms is crucial.

[0004] While atomic layer deposition offers the aforementioned advantages, the surface of an untreated organic substrate is primarily carbon-based and has a very low oxygen content. Therefore, the inorganic aluminum oxide layer can only form simple physical adsorption or very weak C-Al chemical bonds on the organic substrate surface. The currently widely used alternating organic-inorganic multilayer structure is not only complex to prepare, but the interface between the inorganic layer and the organic substrate easily becomes a channel for water vapor diffusion, resulting in unsatisfactory results. Therefore, further improvements are urgently needed in this field to meet the higher quality and higher requirements of the atomic layer deposition aluminum oxide film preparation process. Summary of the Invention

[0005] In response to the above-mentioned deficiencies in the prior art and technical requirements, the present invention provides an atomic layer infiltration deposition composite film and a preparation method thereof that improves the adhesion of aluminum oxide on the surface and inside of a flexible substrate based on strong AI-O bonding. The present invention, by fully combining the characteristics and requirements of the atomic layer deposition aluminum oxide film packaging process, pre-treats the organic substrate in a targeted manner, adjusts the parameters and procedures of the entire atomic layer deposition process, and accordingly can perform the entire aluminum oxide film adhesion modification process efficiently and with high quality under simpler, easier-to-control deposition process conditions. A compact organic-inorganic hybrid structure with AI-O bonding is formed inside the flexible substrate, and an aluminum oxide structure with strong AI-O bonding is attached to the surface of the flexible substrate, which is particularly suitable for packaging applications. To achieve the above-mentioned purpose of the present invention, the present invention adopts the following technical solutions:

[0006] First, the present invention provides an atomic layer infiltration deposition composite film with strong Al-O bonding, comprising an organic layer and an organic-inorganic hybrid layer, including or excluding an inorganic layer. The material of the organic layer is preferably a flexible substrate material, such as at least one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyimide (PI) as the main material, although PET, PEN, or PI can also be directly used as the flexible substrate. The organic-inorganic hybrid layer is a hybrid layer of organic and inorganic materials formed by atomic layer infiltration of inorganic materials within the organic layer, i.e., a composite layer formed by the organic layer and the inorganic layer, with strong Al-O bonding formed between the inorganic layer and the organic layer. The material of the inorganic layer is preferably an inorganic material with aluminum oxide (Al2O3) as the main body, doped or not doped with titanium oxide (TiO2) and / or zirconium oxide (ZrO2), although aluminum oxide can also be directly used.

[0007] For the composite film, the thickness of the organic-inorganic hybrid layer is preferably 1-10 nm, and a strong Al-O bonding can be formed inside the organic layer.

[0008] Regarding the composite film, wherein the atomic layer deposition composite film further comprises an inorganic layer, and the thickness of the inorganic layer is 5-50nm. When the composite film does not include an inorganic layer, the composite film is a binary composite film structure, specifically, it may include but is not limited to PET / PET-AI2O3, PET / PET-TiO2, PET / PET-ZrO2, PEN / PEN-AI2O3, PEN / PEN-TiO2, PEN / PEN-ZrO2, PI / PI-AI2O3, PI / PI-TiO2, PI / PI-ZrO2; when the composite film includes an inorganic layer, the composite film is a ternary composite film structure. Composite film structures, specifically, may include but are not limited to PET / PET-Al2O3 / Al2O3, PET / PET-TiO2 / TiO2, PET / PET-ZrO2 / ZrO2, PEN / PEN-Al2O3 / Al2O3, PEN / PEN-TiO2 / TiO2, PEN / PEN-ZrO2 / ZrO2, PI / PI-Al2O3 / Al2O3, PI / PI-TiO2 / TiO2, and PI / PI-ZrO2 / ZrO2. The inventors have discovered that the presence of an inorganic layer depends on the depth of penetration of the inorganic layer into the organic layer and the number of cycles of the inorganic layer. If the number of cycles is low and the shut-off valve is closed for a long time, there may be no inorganic layer. If the number of cycles is high and the shut-off valve is closed for a short time, the inorganic layer partially penetrates into the flexible substrate to form an organic-inorganic hybrid layer, and partially forms an inorganic layer on the surface of the flexible substrate. When there is no inorganic layer, the thickness of the organic-inorganic hybrid layer directly reaches the predetermined deposition thickness.

[0009] For the composite film, the thickness of the organic layer may be 100-125 μm, and strong Al-O bonding can be formed on the surface of the organic layer.

[0010] Secondly, the present invention also provides a method for preparing the above-mentioned atomic layer deposition composite film, which includes introducing a metal organic precursor to atomically deposit an inorganic layer on the surface of the organic layer. Preferably, it can also include the step of corona treating the surface of the organic layer before atomic layer deposition of the inorganic layer. The corona treatment introduces oxygen-containing binding sites to further form strong AI-O bonding. Conventional atomic layer deposition processes do not involve corona pretreatment. Figure 2 Comparing the film structures before and after corona treatment: In conventional composite structures, the inorganic layer is simply physically adsorbed on the PEN surface and remains on the substrate surface without penetrating into the interior. However, after corona treatment, the present invention allows some of the inorganic layer to diffuse into the interior of the substrate, while others are deposited on the surface, forming strong Al-O bonds both within and on the substrate surface.

[0011] Preferably, the preparation method described above may further include a step of maintaining the pressure for 20-110 seconds after the metal-organic precursor is introduced. In conventional atomic layer deposition processes, nitrogen is immediately purged after the metal-organic precursor pulse, resulting in a chamber pressure of only a few tenths of a Torr. Therefore, the present invention introduces a shut-off valve closing process to significantly increase the pressure after the metal-organic precursor pulse, thereby increasing the probability of the metal precursor diffusing into the flexible substrate, further achieving modification of the composite film.

[0012] Preferably, the preparation method described above further includes the step of introducing an oxygen source precursor and maintaining the pressure for 20-110 seconds. In conventional atomic layer deposition processes, although the pressure can reach several hundred Torr after the ozone pulse, the pressure immediately drops after the nitrogen purge, and the pressure in the cavity cannot be maintained at a relatively high value. Therefore, by closing the stop valve, the pressure in the cavity is maintained at a relatively high value, increasing the probability of the oxygen source precursor diffusing into the flexible substrate, and further realizing the modification of the composite film. Figure 5 The differences in barrier properties among the blank control / corona pretreatment / corona + modified composite films further illustrate that the composite film synthesized by the present invention has been greatly improved in performance.

[0013] As a more preferred solution, the method for preparing the above-mentioned atomic layer deposition composite film of the present invention may include the following steps:

[0014] (1) Perform corona treatment on the surface of organic substrate: First, check whether the equipment is well grounded and whether the connection line between the discharge platform and the control box is loose. After the preparation is completed, set the current position of the panel to 0, the working times to 1, and adjust the discharge power to 0.8-1.5kw. Finally, place the treated material flat on the discharge platform and press the high-voltage start button.

[0015] (2) placing the organic substrate into an atomic layer deposition reactor, setting the reaction temperature of the atomic layer deposition chamber to 80°C-100°C, setting the air inlet and outlet temperatures of the atomic layer deposition chamber to 150°C-200°C, and cleaning the precursor passage;

[0016] (3) introducing a metal organic precursor pulse for a time length of 0.02s-2s, and then closing the stop valve for 20s-110s, wherein the metal organic precursor is an organic metal containing at least trimethylaluminum, which may or may not contain tetramethyl(dimethylamino)titanium and / or tetrakis(dimethylamide)zirconium; introducing a purge gas to remove the residue inside the sealed cavity;

[0017] (4) introducing an oxygen source precursor pulse for a time length of 0.5s-3s, and then closing the stop valve for 20s-110s, wherein the oxygen source precursor is ozone or pure water; introducing a purge gas to remove the residue inside the sealed cavity;

[0018] (5) Repeat steps (3) and (4) until the deposition thickness reaches the preset thickness.

[0019] Preferably, in the preparation method described above, the precursor cleaning passage in step (2) is to introduce a metal organic precursor pulse into the sealed cavity of the reactor, the time length is 0.02s-0.1s, the waiting time is set to 5s-10s, and the number of cycles is 10-50 times.

[0020] Preferably, in the preparation method described above, the oxygen source precursor in step (4) is ozone or pure water, with ozone being more preferred because the deposition temperature of the present invention is relatively low, and water is prone to undergoing a CVD chain reaction at relatively low temperatures, which can lead to surface defects and pinholes in the film, thereby affecting the film's barrier properties. Furthermore, since ozone is a gas, its pressure increase during the closing of the stop valve is much greater than that of a liquid, thus increasing its probability of penetrating into the substrate, further contributing to improved barrier properties.

[0021] Preferably, in the above-mentioned preparation method, the number of repeated cycles in step (5) is 40-300 times.

[0022] Furthermore, the method for preparing the above-mentioned atomic layer deposition composite film of the present invention may include the following steps:

[0023] (a) Preprocessing step

[0024] The flexible substrate to be processed is first cleaned, dried and placed on the surface of the corona treatment equipment, and a high-voltage operation is performed.

[0025] (b) Preparatory deposition and heating steps

[0026] The pretreated organic substrate was quickly placed into the sealed chamber of atomic layer deposition, the exhaust valve was opened to pump the reaction chamber pressure to below 1 Torr, the nitrogen carrier gas flow rate was set to 20 sccm and the carrier gas was introduced into the chamber for cleaning, the chamber reaction temperature of atomic layer deposition was set to 80℃-100℃, and the air inlet and outlet temperatures of the atomic layer deposition chamber were set to 150℃-200℃.

[0027] (c) Atomic layer deposition reaction steps for modified composite films

[0028] When the internal reaction temperature of the sealed cavity and the air inlet and outlet temperatures reach stable preset temperatures, the atomic layer deposition reaction step of the modified composite film is performed, and the above-mentioned carrier gas is continuously loaded throughout the entire process.

[0029] Furthermore, the pre-processing step (a) may specifically include the following steps:

[0030] (a1) The flexible substrate surface is first cleaned using acetone, anhydrous ethanol, and deionized water, sequentially. Acetone is used to remove organic stains from the organic substrate surface, anhydrous ethanol is used to remove residual acetone and inorganic impurities, and deionized water is used to remove ethanol and inorganic impurities from the substrate surface. The cleaning steps are performed in a clean ultrasonic cleaning machine, and the cleaning time for all solvents is set to 10 minutes. After cleaning, the surface is wiped clean of any residual moisture with a dust-free paper.

[0031] (a2) The cleaned organic substrate was placed in a vacuum drying oven set at 60°C and dried for 8 h.

[0032] (a3) The organic substrate is cut into 100 mm x 100 mm square samples, with the coated surface facing up. The flexible substrate is then corona treated. This pretreatment generates a large amount of ozone, a strong oxidant that oxidizes plastic molecules and creates oxygen-containing groups on their surface, significantly increasing their surface energy. This in turn improves the adhesion of the inorganic layer to the flexible substrate and its surface.

[0033] Furthermore, the atomic layer deposition reaction step of modifying the composite film in step (c) may specifically include the following:

[0034] (c1) Cleaning the metal organic precursor passage: introducing a metal organic precursor pulse into the sealed cavity, the time length is 0.02s-0.1s, the waiting time is set to 5s-10s, and the number of cycles is 10 times-50 times.

[0035] (c2) A metal organic precursor pulse is introduced into the sealed cavity for a time length of 0.02s-2s to increase the amount of metal organic precursor introduced, and then the stop valve is closed and waited for a time length of 20s-110s to allow the metal organic precursor to diffuse and penetrate the surface of the organic substrate, thereby filling the free volume of the organic substrate to form a compact organic-inorganic hybrid layer, wherein the precursor is TMA trimethylaluminum, TDMAT tetramethyl(dimethylamino)titanium or TDMA tetrakis(dimethylamide)zirconium.

[0036] (c3) Opening the stop valve for 10s-30s, and introducing a purge gas to remove the first precursor and reaction byproducts remaining in the sealed cavity.

[0037] (c4) introducing a pulse of an oxygen source precursor into the sealed cavity for a period of 0.5s-3s, then closing the shut-off valve and waiting for a period of 20s-110s, so that the metal organic precursor infiltrated into the surface of the flexible substrate reacts with the aforementioned oxygen source precursor to form an organic-inorganic hybrid layer, wherein the aforementioned oxygen source precursor is ozone or pure water.

[0038] (c5) Opening the stop valve for 10s-30s, and introducing a purge gas to remove the first precursor and reaction byproducts remaining in the sealed cavity.

[0039] (c6) Repeat sub-steps (c2) to (c5) in a cycle, preferably, the number of cycles is 40-300 times, until the thickness of the deposited inorganic layer reaches a preset thickness, thereby completing the preparation of the desired strong chemical bond and modified composite film.

[0040] As a preferred solution, in step (b), high-pressure nitrogen is preferably used to perform a cleaning process on the target substrate, and the vacuum operation is set to make the internal pressure of the sealed cavity less than or equal to 1 Torr.

[0041] As a further preferred solution, before the organic substrate sample is placed into the sealed cavity and after the sample is taken out from the sealed cavity, the sealed cavity needs to be operated in step (c1). The saturated vapor pressure of the metal organic precursor is relatively large and can be easily cleaned and converted into a gaseous state.

[0042] As a further preferred solution, in step (c1), the metal organic precursor is used as the first precursor, preferably trimethylaluminum. In step (c4), the oxygen source precursor is used as the second precursor, preferably gaseous ozone.

[0043] The inventors found that the thickness of the organic-inorganic hybrid layer is determined by the number of cycles and the closing time of the stop valve. However, the penetration of the inorganic layer material into the interior of the organic flexible substrate is limited, and it is difficult to accurately control the thickness of the inorganic layer penetration. Moreover, during the experiment, we generally prefer a longer closing time of the stop valve and a relatively large number of cycles. Therefore, after the organic-inorganic hybrid layer is formed, a partial inorganic layer will generally be formed.

[0044] The present invention's method for preparing an atomic layer deposition composite thin film enables atomic layer deposition of an inorganic layer within an organic layer while simultaneously depositing an inorganic layer on the surface of the organic layer. Therefore, the present invention provides a method for improving the adhesion of an inorganic coating to the surface and interior of an organic substrate. This method is used to form a compact organic-inorganic hybrid layer with strong Al-O bonding within a flexible substrate, and to form an inorganic coating with strong Al-O bonding on the surface of the flexible substrate. The present invention relates to inorganic thin film material technology, and more specifically, to corona treatment of a flexible substrate to improve the adhesion of an inorganic coating to the surface and interior of the flexible substrate.

[0045] Compared with the prior art, the technical advantages of the present invention are:

[0046] 1. The modified composite film with strong Al-O bonds prepared by this invention is primarily based on an organic thin film material with excellent light transmittance and mechanical properties. It leverages the advantages of corona pretreatment, which introduces oxygen-containing groups on the surface of a flexible substrate, thereby increasing the polymer's surface energy. Taking full advantage of the characteristics and requirements of the atomic layer deposition (ALD) aluminum oxide thin film encapsulation process, a shut-off valve is specifically introduced during the ALD process. This significantly increases the pressure after the metal precursor pulse, significantly enhancing the precursor's penetration and diffusion within the flexible substrate. This allows for the formation of strong Al-O bonds within and on the surface of the organic thin film material, further enhancing the film's barrier capability. Simultaneously, the process steps and reaction mechanisms of the entire process were studied and improved. Actual testing demonstrates that not only can the aluminum oxide film modification be performed at temperatures below 100°C, but the desired modified composite film with strong chemical bonds can be obtained with greater efficiency and higher quality.

[0047] 2. The corona pretreatment described in this invention introduces oxygen-containing groups onto the surface of the flexible substrate, thereby increasing the polymer's surface energy. This significantly enhances the adhesion and bonding of aluminum oxide to and on the flexible substrate, enabling the formation of a compact organic-inorganic hybrid layer with strong Al-O bonding and an inorganic layer with strong Al-O chemical bonding. Furthermore, the amorphous α-Al2O3 structure prepared in this invention is the most stable phase of aluminum oxide. The smooth, bright α-Al2O3 film reduces surface light scattering, resulting in excellent optical properties.

[0048] 3. The components provided by the present invention form an organic / organic-inorganic / inorganic composite structure (representing a three-layer structure), and good interfacial contact is formed between the layers. The strong Al-O bonding greatly improves the adhesion between the inorganic layer and the organic layer. The mutual coupling between the different functional layers can effectively reduce the defect density of each layer and improve the overall performance of the composite material.

[0049] 4. The process method of the present invention is easy to operate as a whole, has strong adaptability, and is characterized by high efficiency and high quality. Therefore, it is particularly suitable for packaging application scenarios of modified alumina composite films. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic diagram of the overall process flow of the strong chemical bond and modified composite film constructed according to the preferred embodiment of the present invention.

[0051] Figure 2 In the conventional composite structure shown, the inorganic layer is simply physically adsorbed on the PEN surface and remains on the substrate surface without penetrating into the interior. The corona pretreatment modified composite film is a schematic structural diagram of a modified composite film with strong Al-O bonding synthesized in an embodiment of the present invention. Part of the inorganic layer diffuses into the interior of the substrate, while part is deposited on the surface, forming strong Al-O bonding both within and on the substrate surface.

[0052] Figure 3 Schematic diagram of the reaction mechanism of the modified composite film with strong Al-O bonding synthesized according to the present invention.

[0053] Figure 4 This figure shows a comparison of the XPS spectra of a modified composite film (Example 4) after corona treatment and an unmodified composite film. The Al content in the surface layer of the modified composite film is significantly increased. The unmodified composite film (Example 3) was obtained by introducing the first and second precursors without waiting for 20-110 seconds.

[0054] Figure 5 1 is a comparison of the water vapor transmission rates of the composite film of the present invention that has been corona pretreated and modified (Example 1), the composite film that has been corona pretreated but not modified (Example 2), and the film that has not been corona pretreated and not modified (Example 5) measured using the Membrane Instrument Method. DETAILED DESCRIPTION

[0055] The following embodiments are further descriptions of the present invention to illustrate the technical content of the present invention, but the essential content of the present invention is not limited to the following embodiments. Ordinary technicians in this field can and should know that any simple changes or replacements based on the essential spirit of the present invention should fall within the scope of protection required by the present invention.

[0056] The corona pretreatment modified composite film according to the present invention is used to form a compact organic-inorganic hybrid layer with Al-O bonding inside the target substrate and to form an aluminum oxide film with strong Al-O bonding on the surface of the target substrate, and mainly comprises the following steps:

[0057] Step 1: Preprocessing step

[0058] The flexible substrate to be processed is first cleaned, dried and then subjected to corona pretreatment.

[0059] The flexible substrate surface is first cleaned using acetone, anhydrous ethanol, and deionized water, sequentially. Acetone is used to remove organic stains from the organic substrate surface, anhydrous ethanol is used to remove residual acetone and inorganic impurities, and deionized water is used to remove ethanol and inorganic impurities from the substrate surface. The cleaning steps are performed in a clean ultrasonic cleaning machine, and the cleaning time for all solvents is set to 10 minutes. After cleaning, the surface is wiped clean of any residual moisture with a dust-free paper towel.

[0060] Then, the cleaned organic substrate was placed in a vacuum drying oven and dried at 60° C. for 8 h.

[0061] Then cut the organic substrate into 100mm*100mm square samples, first check whether the corona equipment is well grounded, check whether the connection line between the discharge platform and the control box is loose, and after the preparation is completed, set the current position of the panel to 0, the working times to 1, and adjust the discharge power to about 1kw. Finally, place the processed material flat on the discharge platform and press the high-voltage start button.

[0062] Step 2: Preparatory deposition and heating steps

[0063] The pretreated organic substrate was quickly placed into the sealed chamber of atomic layer deposition, the exhaust valve was opened to pump the reaction chamber pressure to below 1 Torr, the nitrogen carrier gas flow rate was set to 20 sccm and the carrier gas was introduced into the chamber for cleaning, the chamber reaction temperature of atomic layer deposition was set to 80℃-100℃, and the air inlet and outlet temperatures of the atomic layer deposition chamber were set to 150℃-200℃.

[0064] Step 3: Atomic layer infiltration deposition reaction step

[0065] The pretreated organic substrate was quickly placed into the sealed chamber of atomic layer deposition, the exhaust valve was opened to pump the reaction chamber pressure to below 1 Torr, the nitrogen carrier gas flow rate was set to 20 sccm and the carrier gas was introduced into the chamber for cleaning, the chamber reaction temperature of atomic layer deposition was set to 80℃-100℃, and the air inlet and outlet temperatures of the atomic layer deposition chamber were set to 150℃-200℃.

[0066] First, clean the metal organic precursor passage: introduce a metal organic precursor pulse into the sealed cavity, the time length is 0.02s-0.1s, the waiting time is set to 5s-10s, and the number of cycles is 10 times-50 times (this step does not participate in the cycle).

[0067] Then, a metal organic precursor pulse is introduced into the sealed cavity for a time length of 0.02s-2s to increase the amount of metal organic precursor introduced, and then the stop valve is closed and waited for a time length of 20s-110s to allow the metal organic precursor to diffuse and penetrate inside the organic substrate, thereby filling the free volume of the organic substrate to form a compact organic-inorganic hybrid layer, wherein the precursor is TMA trimethylaluminum, TDMAT tetramethyl (dimethylamino) titanium or TDMA tetrakis (dimethylamide) zirconium.

[0068] Next, the stop valve is opened for 20 seconds, and a purge gas is introduced to remove the first precursor and reaction by-products remaining in the sealed cavity.

[0069] Then, an oxygen source precursor pulse is introduced into the sealed cavity for a time length of 0.5s-3s, and then the stop valve is closed and waiting is carried out. The waiting time is set to 20s-110s, so that the metal organic precursor infiltrated into the flexible substrate reacts with the aforementioned oxygen source precursor to form an organic-inorganic hybrid layer, wherein the aforementioned oxygen source precursor is ozone or pure water.

[0070] Then, the stop valve is opened for 20 seconds, and a purge gas is introduced to remove the first precursor and reaction by-products remaining in the sealed cavity.

[0071] The sub-steps are repeated cyclically, preferably, the number of cycles is 40-300 times, until the thickness of the inorganic layer deposited on the surface of the target substrate reaches a preset thickness, thereby completing the preparation of the desired strong chemical bond and modified composite film.

[0072] The present invention will be more clearly explained below through the use of several specific examples. For illustrative purposes, the instruments employed in these examples may include a Mocon water vapor transmission rate tester and an X-ray photoelectron spectrometer, and the reagents employed may include, for example, a PEN film, a carrier gas (nitrogen), an aluminum source (trimethylaluminum), and an oxygen source (ozone).

[0073] Example 1

[0074] Using atomic layer infiltration deposition technology, 200 cycles of aluminum oxide were grown on the surface of PEN organic thin film material that had been corona pretreated. The method includes the following steps:

[0075] First, PEN is corona pre-treated. During the corona treatment discharge process, a large amount of ozone is generated. Ozone is a strong oxidant that oxidizes plastic molecules and produces polar oxygen-containing groups such as carbonyl and peroxide on their surface, thereby increasing their surface energy and helping aluminum oxide form strong Al-O bonds on the surface and inside PEN. Corona treatment introduces a large number of oxygen-containing group binding sites, achieving the removal of carbon sources on the PEN surface. In the TMA half-cycle, the oxygen-containing groups at the end of the substrate surface react with TMA through a proton transfer ligand exchange reaction to form Al-O bonds and release volatile products. In the O3 half-cycle, the remaining surface methyl ligands react with the incoming ozone molecules through another proton transfer ligand exchange reaction. The strong Al-O bond is the main driving force of the surface reaction, and its reaction enthalpy is one of the highest among all ALD reactions. The reaction equations for the two half-reactions are as follows:

[0076] ||-O-C+AI(CH3)3(g)→||-O-Al(CH3)2+CH4(g)

[0077] ||-Al-CH3+O3(g)→||-Al-OH+CH4(g)

[0078] Next, prepare the alumina inorganic layer as follows:

[0079] (a1) Place the corona-treated PEN organic thin film sample into the chamber of an atomic layer deposition reactor. Set the chamber reaction temperature to 100°C. Open the exhaust valve to reduce the reaction chamber pressure to below 1 Torr. Set the nitrogen carrier gas flow rate to 20 sccm and introduce the carrier gas to clean the chamber. Set the chamber reaction temperature of the atomic layer deposition to 100°C. Set the temperature of the atomic layer deposition chamber inlet and outlet to 150°C.

[0080] (a2) Cleaning the metal organic precursor passage: a metal organic precursor pulse is introduced into the sealed cavity, the duration is 0.02 s, the waiting time is set to 10 s, and the number of cycles is 20.

[0081] (a3) The metal organic precursor TMA is introduced for a duration of 0.02 s, and then the shutoff valve is closed and a waiting period is set for 20 s. This allows TMA to fully penetrate the interior of the PEN film and fully combine with the oxygen-containing groups on the PEN surface to form strong AI-O bonds. Strong AI-O bonds are the main driving force of surface reactions, and their reaction enthalpy is one of the highest among all ALD reactions.

[0082] (a4) Opening the stop valve for 30 seconds and introducing a purge gas to remove the first precursor and reaction byproducts remaining in the sealed cavity.

[0083] (a5) The oxygen source precursor O3 is introduced for a period of 0.5 s to increase the amount introduced, and then the stop valve is closed and a waiting period is set to 20 s to allow the TMA that has infiltrated the PEN to react with the aforementioned O3 precursor to form a composite structure.

[0084] (a6) Opening the stop valve for 30 seconds and introducing a purge gas to remove the second precursor and reaction byproducts remaining in the sealed cavity.

[0085] (a7) Repeating substeps (a3) to (a6), preferably 200 times, until the thickness of the deposited inorganic layer reaches a predetermined thickness, thereby completing the preparation of the desired strong Al-O bond and atomic layer infiltration deposition composite film. Step (a2) must be performed on the sealed chamber before and after the sample is placed in the sealed chamber.

[0086] Example 2

[0087] Atomic layer deposition (ALD) was used to grow 200 cycles of aluminum oxide on the surface of a corona-pretreated PEN organic thin film material. The method includes the following steps:

[0088] (a1) Place the corona-treated PEN organic thin film sample into the chamber of an atomic layer deposition reactor. Set the chamber reaction temperature to 100°C. Open the exhaust valve to reduce the reaction chamber pressure to below 1 Torr. Set the nitrogen carrier gas flow rate to 20 sccm and introduce the carrier gas to clean the chamber. Set the chamber reaction temperature of the atomic layer deposition to 100°C. Set the temperature of the atomic layer deposition chamber inlet and outlet to 150°C.

[0089] (a2) Cleaning the metal organic precursor passage: a metal organic precursor pulse is introduced into the sealed cavity, the duration is 0.02 s, the waiting time is set to 10 s, and the number of cycles is 20.

[0090] (a3) A pulse of metal organic precursor (TMA, the first precursor) is introduced to allow TMA to fully combine with oxygen-containing groups on the PEN surface to form strong AI-O bonds. Strong AI-O bonds are the main driving force of surface reactions, and their reaction enthalpy is one of the highest among all ALD reactions. The reaction time is set to 0.02 s. The introduction of TMA into the chamber is stopped, and a purge gas is continuously introduced into the chamber to purge the remaining first precursor TMA and reaction byproducts in the chamber. This process lasts for 30 s.

[0091] (a4) A pulse of a second precursor, O3, is introduced into the chamber to react with the first precursor on the surface of the PEN substrate to be deposited, and the duration is 0.5 s. Then, the introduction of the second precursor, O3, into the chamber is stopped, and a cleaning gas is continuously introduced into the chamber to clean the residual precursor and reaction byproducts in the chamber, and the process lasts for 10 s.

[0092] (a5) Repeating substeps (a3) to (a4), preferably 200 times, until the thickness of the deposited inorganic layer reaches a predetermined thickness, thereby completing the preparation of the desired composite film with strong Al-O bonds and atomic layer infiltration deposition. Step (a2) must be performed on the sealed chamber before and after the sample is placed in the sealed chamber.

[0093] Example 3

[0094] Atomic layer deposition (ALD) was used to grow 40 cycles of aluminum oxide on the surface of a corona-pretreated PEN organic thin film material. The method includes the following steps:

[0095] (a1) Place the corona-treated PEN organic thin film sample into the chamber of an atomic layer deposition reactor. Set the chamber reaction temperature to 100°C. Open the exhaust valve to reduce the reaction chamber pressure to below 1 Torr. Set the nitrogen carrier gas flow rate to 20 sccm and introduce the carrier gas to clean the chamber. Set the chamber reaction temperature of the atomic layer deposition to 100°C. Set the temperature of the atomic layer deposition chamber inlet and outlet to 150°C.

[0096] (a2) Cleaning the metal organic precursor passage: a metal organic precursor pulse is introduced into the sealed cavity, the duration is 0.02 s, the waiting time is set to 10 s, and the number of cycles is 20.

[0097] (a3) A pulse of the metal organic precursor trimethylaluminum is introduced to allow the trimethylaluminum to fully combine with the oxygen-containing groups on the PEN surface to form a strong Al-O bond. The strong Al-O bond is the main driving force of the surface reaction, and its reaction enthalpy is one of the highest among all ALD reactions. The reaction time is set to 0.02 s. The introduction of trimethylaluminum into the chamber is stopped, and the purge gas is continuously introduced into the chamber to purge the remaining first precursor trimethylaluminum and reaction byproducts in the chamber. This process lasts for 30 s.

[0098] (a4) A pulse of a second precursor, ozone, is introduced into the cavity to react with the first precursor on the surface of the PEN substrate to be deposited, and the duration is 0.5 s. The introduction of the second precursor, ozone, into the cavity is stopped, and a cleaning gas is continuously introduced into the cavity to clean the residual precursor and reaction byproducts in the cavity, and the process lasts for 10 s.

[0099] (a5) Repeating substeps (a3) to (a4), preferably forty times, until the thickness of the inorganic layer deposited on the target substrate reaches a predetermined thickness, thereby completing the preparation of the desired composite film with strong Al-O bonds and atomic layer infiltration deposition. Step (a2) must be performed on the sealed chamber before and after the sample is placed in the sealed chamber.

[0100] Example 4

[0101] Using atomic layer infiltration deposition technology, 40 cycles of aluminum oxide were grown on the surface of PEN organic thin film material that had been corona pretreated. The method includes the following steps:

[0102] (a1) Place the corona-treated PEN organic thin film sample into the chamber of an atomic layer deposition reactor. Set the chamber reaction temperature to 100°C. Open the exhaust valve to reduce the reaction chamber pressure to below 1 Torr. Set the nitrogen carrier gas flow rate to 20 sccm and introduce the carrier gas to clean the chamber. Set the chamber reaction temperature of the atomic layer deposition to 100°C. Set the temperature of the atomic layer deposition chamber inlet and outlet to 150°C.

[0103] (a2) Cleaning the metal organic precursor passage: a metal organic precursor pulse is introduced into the sealed cavity, the duration is 0.02 s, the waiting time is set to 10 s, and the number of cycles is 20.

[0104] (a3) A pulse of the metal organic precursor TMA is introduced with a duration of 0.02 s, and then the shutoff valve is closed and a waiting period is set for 20 s. This allows TMA to fully penetrate the interior of the PEN film and fully combine with the oxygen-containing groups on the surface and inside the PEN to form strong Al-O bonds. Strong Al-O bonds are the main driving force of surface reactions, and their reaction enthalpy is one of the highest among all ALD reactions.

[0105] (a4) Opening the stop valve for 30 seconds and introducing a purge gas to remove the first precursor and reaction byproducts remaining in the sealed cavity.

[0106] (a5) Ozone, an oxygen source precursor, is introduced in pulses for a duration of 0.5 seconds to increase the amount introduced, and then the stop valve is closed and a waiting period is set to 20 seconds to allow the trimethylaluminum that has infiltrated the surface of the PEN to react with the aforementioned ozone precursor to form a composite structure.

[0107] (a6) Opening the stop valve for 30 seconds and introducing a purge gas to remove the second precursor and reaction byproducts remaining in the sealed cavity.

[0108] (a7) Repeating sub-steps (a3) to (a6), preferably forty times, until the thickness of the inorganic layer deposited on the surface of the target substrate reaches a predetermined thickness, thereby completing the preparation of the desired modified composite film with strong chemical bonds. Step (a2) must be performed on the sealed cavity before and after the sample is removed from the sealed cavity.

[0109] Example 5

[0110] Atomic layer deposition (ALD) was used to grow 200 cycles of aluminum oxide on the surface of a PEN organic thin film material that had not been corona pretreated. The method included the following steps:

[0111] (a1) Place the PEN organic thin film sample into the chamber of the atomic layer deposition reactor, set the chamber reaction temperature to 100°C, open the exhaust valve to pump the reaction chamber pressure to below 1 Torr, set the nitrogen carrier gas flow rate to 20 sccm and introduce the carrier gas to purge the chamber, set the chamber reaction temperature of the atomic layer deposition to 100°C, and set the atomic layer deposition chamber air inlet and outlet temperatures to 150°C.

[0112] (a2) Cleaning the metal organic precursor passage: a metal organic precursor pulse is introduced into the sealed cavity, the duration is 0.02 s, the waiting time is set to 10 s, and the number of cycles is 20.

[0113] (a3) A pulse of the metal organic precursor TMA is introduced to allow TMA to fully combine with the oxygen-containing groups on the PEN surface to form strong Al-O bonds. Strong Al-O bonds are the main driving force of surface reactions, and their reaction enthalpy is one of the highest among all ALD reactions. The reaction time is set to 0.02 s. The introduction of TMA into the chamber is stopped, and a purge gas is continuously introduced into the chamber to purge the remaining first precursor TMA and reaction byproducts in the chamber. This process lasts for 30 s.

[0114] (a4) A pulse of a second precursor, O3, is introduced into the chamber to react with the first precursor on the surface of the PEN substrate to be deposited, and the duration is 0.5 s. Then, the introduction of the second precursor, O3, into the chamber is stopped, and a cleaning gas is continuously introduced into the chamber to clean the residual precursor and reaction byproducts in the chamber, and the process lasts for 10 s.

[0115] (a5) Repeating sub-steps (a3) to (a4), preferably 200 times, until the thickness of the deposited inorganic layer reaches a predetermined thickness, thereby completing the preparation of the composite film. Step (a2) must be performed on the sealed cavity before the sample is placed in the sealed cavity and after the sample is removed from the sealed cavity.

[0116] Next, the elemental composition and content of the surface of the modified composite film obtained according to the process method of the present invention will be tested by X-ray photoelectron spectroscopy, and the water vapor permeability of the modified composite film obtained according to the process method of the present invention will be tested by a membrane water vapor permeability tester.

[0117] Figure 1 The figure is a schematic diagram of the overall preparation process of the modified composite film with strong Al-O bonding constructed according to the present invention. Figure 2 In the conventional composite structure shown, the inorganic layer is simply physically adsorbed on the PEN surface and remains on the substrate surface without penetrating into the interior. The corona pretreatment modified composite film is a schematic structural diagram of a modified composite film with strong Al-O bonding synthesized in an embodiment of the present invention. Part of the inorganic layer diffuses into the interior of the substrate, while part is deposited on the surface, forming strong Al-O bonding both within and on the substrate surface. Figure 3 Schematic diagram of the reaction mechanism of the composite film with strong Al-O bond and atomic layer infiltration deposition synthesized according to the present invention. Figure 1 、 2 As shown in Figure 3, the present invention effectively overcomes the process difficulties such as poor adhesion between the inorganic layer and the organic layer at a low deposition temperature, unsatisfactory optical and mechanical properties of the film, etc. by studying and modifying the processing method, reaction mechanism and multiple key parameters of the entire process. Therefore, the composite film is particularly suitable for packaging applications of atomic layer deposited aluminum oxide films.

[0118] The XPS results of the 40-cycle composite film in Examples 3 and 4 are as follows: Figure 4 As shown in the figure (since XPS can only measure the element content of about 10nm on the surface, we use 40 cycles) the AI element content in the surface of the modified composite film increases significantly.

[0119] The WVTR test results of 200 cycles of composite films in Examples 1, 2, and 5 are as follows: Figure 5 As shown in the figure, compared with the conventional PEN substrate that has not been corona treated and has not been modified, the barrier properties of the PEN organic film after corona treatment and corona + modification treatment are greatly improved.

[0120] In summary, compared with the existing technical solutions, this solution can realize the synthesis process of atomic layer infiltration deposition composite films with strong Al-O bonding in a manner that is easy to operate and highly applicable. It can not only significantly increase the Al element content on the surface of the final product, but also effectively improve the barrier properties of the PEN film. Therefore, it is particularly used in packaging applications of atomic layer deposition aluminum oxide films.

[0121] It should be noted that the technical contents of the present invention described above are only for the purpose of explaining and illustrating the technical essence of the present invention to enable those skilled in the art to understand the technical essence of the present invention. Therefore, the technical contents described above are not intended to limit the substantial protection scope of the present invention. The substantial protection scope of the present invention shall be based on the claims. Those skilled in the art should be aware that any modifications, equivalent substitutions, and improvements based on the substantial spirit of the present invention shall fall within the substantial protection scope of the present invention.

Claims

1. A method for preparing a composite film with strong Al-O bonding by atomic layer infiltration deposition, wherein the composite film comprises an organic-inorganic hybrid layer, wherein the organic-inorganic hybrid layer is a composite layer formed by the infiltration of an inorganic layer material into an organic layer, characterized in that: The preparation method comprises the following steps: (1) Corona pretreatment of the organic flexible substrate; (2) Place the organic substrate in an atomic layer deposition reactor, set the reaction temperature of the atomic layer deposition chamber to 80°C-100°C, set the temperature of the atomic layer deposition chamber inlet and outlet to 150°C-200°C, and clean the precursor passage; (3) introducing a metal organic precursor pulse for a time length of 0.02s-2s, then closing the stop valve and waiting for 20s-110s, wherein the metal organic precursor is an organic metal containing at least trimethylaluminum, which may or may not contain tetramethyl(dimethylamino)titanium and / or tetrakis(dimethylamide)zirconium; introducing a purge gas to remove the residue inside the sealed cavity; (4) introducing an oxygen source precursor pulse for a duration of 0.5s-3s, then closing the stop valve and waiting for 20s-110s, and introducing a purge gas to remove the residue inside the sealed cavity; (5) Repeat steps (3) and (4) until the deposition thickness reaches the preset thickness.

2. The preparation method according to claim 1, wherein The thickness of the organic-inorganic hybrid layer is 1-10 nm.

3. The preparation method according to claim 1, wherein The composite film includes an inorganic layer, and the thickness of the inorganic layer is 5-50 nm.

4. The preparation method according to claim 1, wherein The composite film includes an organic layer, and the thickness of the organic layer is 100-125 μm.

5. The preparation method according to claim 1, wherein The cleaning precursor passage in step (2) is to introduce a metal organic precursor pulse into the sealed cavity of the reactor, the time length is 0.02s-0.1s, the waiting time is set to 5s-10s, and the number of cycles is 10 times-50 times.

6. The preparation method according to claim 1, wherein The number of repeated cycles in step (5) is 40-300 times.

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