A high adhesion metal oxide coating method

Abstract

The application relates to the technical field of material surface, and discloses a high-adhesion metal oxide coating method, which aims to solve the problems of insufficient adhesion, poor compactness and difficulty in being compatible with low-temperature flexible substrates in traditional coating processes. The method comprises the following steps: performing oxygen-argon plasma activation on a substrate to generate high-density active hydroxyl groups; adopting atomic layer deposition to form a metal precursor layer; converting the metal precursor layer into a compact initial film layer in situ through low-temperature plasma-assisted oxidation; depositing a main functional metal oxide film layer through magnetron sputtering; and finally performing gradient annealing treatment to release stress and optimize the crystal lattice structure. Through the above multi-step synergistic process, the chemical bonding between the film layer and the substrate is realized, the adhesion and compactness are significantly improved, the method is suitable for various planar or curved substrates such as silicon wafers, glass, stainless steel and polyimide, and the process compatibility is high, so that the method can meet the large-scale production requirements of semiconductor, display and flexible electronic devices.

Description

Technical Field

[0001] This invention relates to the field of material surface technology, specifically to a method for coating high-adhesion metal oxide films. Background Technology

[0002] With the continuous advancement of advanced manufacturing and precision device technologies, metal oxide coatings are widely used in semiconductors, display panels, photovoltaic devices, and protective coatings due to their excellent optical, electrical, and chemical stability. These coatings are typically prepared using processes such as physical vapor deposition, chemical vapor deposition, or sol-gel methods. Their performance depends not only on the film composition and microstructure but also, and more importantly, on the interfacial bonding strength between the film and the substrate. Under harsh operating conditions such as high humidity, high temperature, or mechanical stress, insufficient adhesion can easily lead to film peeling, cracking, or functional failure, severely limiting the reliability and lifespan of devices.

[0003] However, existing metal oxide coating processes generally suffer from weak interfacial adhesion. On the one hand, traditional deposition methods struggle to form effective chemical bonds on inactive or low surface energy substrates, making the physically adsorbed interfacial bonding susceptible to environmental disturbances. On the other hand, while high-temperature annealing to improve density can enhance crystallinity, it often introduces interfacial stress during cooling due to thermal expansion mismatch, thus weakening adhesion. Furthermore, although some wet chemical methods can form films at low temperatures, residual organic matter or hydroxyl groups are difficult to completely remove, causing interfacial contamination and further reducing the bonding strength between the film and the substrate.

[0004] Therefore, there is an urgent need for a high-adhesion metal oxide coating method that can significantly enhance the interfacial bonding ability between the film layer and various substrates while taking into account both process compatibility and film quality. Summary of the Invention

[0005] The purpose of this invention is to provide a method for coating metal oxides with high adhesion, which can effectively solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for high-adhesion metal oxide coating includes the following specific steps: Step 1: Plasma activation pretreatment of the substrate surface: The substrate to be coated is placed in a vacuum chamber, and a mixture of oxygen and argon is introduced, wherein the volume ratio of oxygen to argon is a predetermined ratio, a radio frequency power of a predetermined power value is applied, and the treatment time is a predetermined time period, so as to generate high-density active hydroxyl groups on the substrate surface; Step 2: Deposition of a metal precursor layer on the activated substrate surface: Atomic layer deposition is used, with titanium tetrachloride or trimethylaluminum as the metal source and water vapor as the oxidant. Under predetermined temperature and pressure conditions, a predetermined number of deposition cycles are performed to form a metal precursor layer with a predetermined thickness; Step 3: Low-temperature plasma-assisted oxidation of the metal precursor layer: The oxidation is carried out at a temperature not exceeding... Under the condition of a preset upper temperature limit, oxygen plasma is introduced, the plasma power is a preset power value, and the processing time is a predetermined time period, so that the metal precursor layer is transformed in situ into a dense metal oxide initial film layer; Step 4: Continue to deposit the main functional metal oxide film layer on the initial film layer: using magnetron sputtering process, with a high-purity metal target as the sputtering source, in an argon-oxygen mixed atmosphere, the oxygen partial pressure ratio is a predetermined ratio, the sputtering power is a preset power value, and the deposition time is a predetermined time period, to form a main functional film layer with a predetermined thickness; Step 5: Perform gradient annealing treatment on the composite film layer: place the coated substrate in an annealing furnace, heat it to the preset annealing temperature at a predetermined heating rate, hold it at the temperature for a predetermined time, and then cool it to room temperature at a predetermined cooling rate to complete the interface stress release and lattice reconstruction.

[0008] Preferably, in step 1, the substrate material includes silicon wafers, glass, stainless steel, or polyimide flexible substrates. After plasma activation treatment, the water contact angle on the substrate surface is less than a preset angle threshold, and the surface energy is increased to above a predetermined surface energy.

[0009] Preferably, in step 2, each cycle of atomic layer deposition includes predetermined time parameters for the metal source pulse time, purge time, oxidant pulse time, and secondary purge time, ensuring that precursor molecules undergo self-limiting chemisorption on the surface and avoiding three-dimensional island growth.

[0010] Preferably, in step 3, during the low-temperature plasma-assisted oxidation process, the plasma electron temperature is controlled within a preset electron temperature range to promote the directional formation of metal-oxygen bonds while suppressing hydroxyl residues, so that the hydroxyl content in the initial film is lower than a preset atomic percentage threshold.

[0011] Preferably, in step 4, magnetron sputtering uses a DC or RF power supply, the target-substrate distance is a predetermined distance, the working gas pressure is a predetermined gas pressure value, and the substrate bias during deposition is a preset negative bias value, so as to enhance the surface migration ability of sputtered particles and improve the film density to a predetermined density or higher.

[0012] Preferably, in step 5, the heating stage of the gradient annealing process is carried out in an inert nitrogen atmosphere, with the oxygen partial pressure lower than a preset low oxygen partial pressure threshold to prevent excessive oxidation of the film; the holding stage is switched to an oxygen-containing atmosphere, with the oxygen partial pressure at a predetermined oxygen partial pressure value to promote the repair of oxygen vacancies at grain boundaries; and the cooling stage is restored to an inert atmosphere to match the difference in thermal expansion coefficients between the substrate and the film.

[0013] Preferably, the main functional metal oxide film is one of titanium dioxide, aluminum oxide, zinc oxide or indium tin oxide, and its crystal structure is anatase, amorphous or cubic phase, which can be controlled by adjusting the sputtering oxygen partial pressure and annealing temperature according to application requirements.

[0014] Preferably, the total thickness of the composite film is within a predetermined thickness range, wherein the thickness ratio of the initial film to the main functional film is a predetermined ratio, which ensures that the interfacial chemical bonding strength is maximized, while maintaining the optical transmittance of the main functional film greater than or equal to a preset transmittance threshold.

[0015] Preferably, the method is applicable to curved or three-dimensional microstructure substrates, and uniform film coating is achieved by rotating the substrate support. The film thickness uniformity deviation is less than the preset uniformity tolerance, the adhesion reaches the preset adhesion level after scratch testing, and the critical load is greater than or equal to the preset load threshold.

[0016] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0017] 1. Significantly improves interface bonding strength

[0018] By combining plasma activation with atomic layer deposition, a high-density active hydroxyl group is constructed on the substrate surface, and an initial chemically bonded metal oxide film is formed in situ, transforming the relationship between the film and the substrate from physical adsorption to chemical bonding. Testing showed that the adhesion of the coating obtained by this invention on a silicon substrate is several times greater than that of the traditional sol-gel method, the critical load for scratch testing is increased from below the preset low load threshold to above the preset high load threshold, and no peeling occurs after aging for a predetermined time under high temperature and high humidity conditions.

[0019] 2. Balancing low-temperature processing and high density

[0020] Low-temperature plasma-assisted oxidation is used instead of high-temperature annealing, and the temperature of key oxidation steps is controlled below a preset low-temperature threshold, which is suitable for flexible substrates such as polyimide. At the same time, through the synergistic effect of magnetron sputtering and gradient annealing, the density of the main functional film layer reaches a predetermined high density and the porosity is lower than the preset porosity threshold, which is significantly better than the porous structure film layer obtained by traditional wet chemical methods, and effectively blocks water vapor and ion permeation.

[0021] 3. Adaptable to various substrates and functional requirements

[0022] This method can prepare various metal oxide films, such as titanium dioxide and aluminum oxide, by adjusting the type of precursor, sputtering parameters, and annealing regime. It is suitable for semiconductors, display panels, photovoltaics, and flexible electronic devices. Even on low surface energy substrates such as polytetrafluoroethylene, this method can still produce stable films with adhesion exceeding a preset adhesion threshold, solving the problem of difficult film formation on inactive substrates using traditional processes.

[0023] 4. Strong process compatibility and scalability

[0024] All steps are completed in standard vacuum equipment, eliminating the need for complex chemical reagents or ultra-high temperature conditions, and are highly compatible with existing semiconductor manufacturing processes. Single-batch processing time is less than the predetermined process cycle, and film thickness uniformity exceeds the preset uniformity tolerance, meeting the industrialization requirements for large-area flat panel displays or roll-to-roll flexible device production. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall technical solution of the coating method of the present invention;

[0026] Figure 2 This is a schematic diagram of the process of synergistic construction of chemically bonded interfaces by plasma activation and atomic layer deposition in this invention;

[0027] Figure 3 This is a flowchart of the multi-stage process flow for low-temperature plasma-assisted oxidation and magnetron sputtering composite film formation in this invention.

[0028] Figure 4 This is a schematic diagram of the gradient annealing process for interface stress release and lattice reconstruction in this invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1

[0031] In the above-described high-adhesion metal oxide coating method, step 1 involves plasma activation pretreatment of the substrate surface. Specifically, the substrate to be coated is placed in a vacuum chamber, and a mixture of oxygen and argon is introduced, wherein the volume ratio of oxygen to argon is a predetermined ratio between 1:4 and 1:9. A preset power value of 50 W to 200 W is applied, and the treatment time is a predetermined period of 30 s to 180 s to generate high-density active hydroxyl groups on the substrate surface. The working pressure of the vacuum chamber is maintained within the range of 1 Pa to 10 Pa. The inlet rates of oxygen and argon are independently adjusted by a mass flow controller to ensure that the deviation of the mixed gas ratio does not exceed ±2%. The operating frequency of the RF power supply is 13.56 MHz, and the matching network automatically adjusts the impedance to maintain stable power output, with its fluctuation range controlled within ±3 W. The substrate is fixed on a heatable electrostatic chuck, and the chuck temperature is maintained between 25 ℃ and 80 ℃ during the treatment process to avoid thermal stress causing substrate deformation. After this treatment, the water contact angle on the substrate surface is less than a preset angle threshold of 10°, and the surface energy is increased to a predetermined surface energy of over 72 mN / m. The substrate material includes silicon wafers, glass, stainless steel, or flexible polyimide substrates. The polyimide substrate has a thickness of 12.5 μm to 125 μm and a glass transition temperature of not less than 360 °C to ensure structural stability in subsequent low-temperature processes. For curved or three-dimensional microstructure substrates, a six-axis rotating support system is used. This support rotates synchronously around the main and secondary axes at a speed of 0.5 rpm to 5 rpm during plasma treatment to ensure uniform plasma bombardment of all exposed surfaces, with surface activation uniformity deviation controlled within ±5%.

[0032] In the above-mentioned high-adhesion metal oxide coating method, step 2 involves depositing a metal precursor layer on the activated substrate surface. Specifically, atomic layer deposition is employed, using titanium tetrachloride (TiCl4) or trimethylaluminum (TMA, Al(CH3)3) as the metal source and water vapor as the oxidant. Under predetermined temperature conditions of 100 ℃ to 250 ℃ and predetermined pressure conditions of 0.1 Torr to 1 Torr, the deposition is cyclically deposited 5 to 50 times to form a metal precursor layer with a thickness of 0.5 nm to 5 nm. Each atomic layer deposition cycle is strictly divided into four sub-steps: A) The metal source pulse time is set to 0.1 s to 1 s; B) The first purging time is set to 5 s to 20 s, using high-purity nitrogen (purity ≥99.999%) at a flow rate of 100 sccm to 500 sccm to remove unreacted precursors; C) The oxidant pulse time is set to 0.05 s to 0.5 s, with water vapor generated by a bubbler at 40 ℃ to 80 ℃ and transported by a carrier gas; D) The second purging time is set to 10 s to 30 s to completely remove reaction byproducts and residual water vapor. The entire cycle time is 16 s to 51.5 s, and the deposition rate is stabilized at 0.1 Å / cycle to 0.3 Å / cycle. The precursor storage tank is equipped with a temperature control system, maintaining TiCl4 at 20 ℃ ± 1 ℃ and TMA at -10 ℃ ± 2 ℃ to ensure constant vapor pressure. The inner wall of the reaction chamber is lined with quartz to prevent metal halides from corroding the chamber. During deposition, the high-density active hydroxyl groups (-OH) on the substrate surface undergo self-limiting chemisorption with the metal precursor molecules, forming M-O-Si or M-O-C bonds (M represents Ti or Al). The monolayer coverage exceeds 95%, effectively avoiding the three-dimensional island growth mode and ensuring that the precursor layer has atomic-level flatness and chemical homogeneity.

[0033] In the above-mentioned high-adhesion metal oxide coating method, step 3 involves low-temperature plasma-assisted oxidation of the metal precursor layer. Specifically, under a preset temperature limit not exceeding 150 °C, oxygen plasma is introduced at a preset power of 30 W to 150 W for a predetermined processing time of 60 s to 300 s, transforming the metal precursor layer in situ into a dense initial metal oxide film. The plasma is generated by an inductively coupled plasma (ICP) source with an operating frequency of 13.56 MHz, an oxygen flow rate of 10 sccm to 50 sccm, and a chamber pressure maintained at 5 mTorr to 20 mTorr. The plasma electron temperature is controlled within a preset electron temperature range of 1.5 eV to 3.0 eV, and the radio frequency power is adjusted in real time using a Langmuir probe to ensure that the electron energy distribution is concentrated in the optimal range for promoting the directional formation of metal-oxygen bonds. Under these conditions, the TiCl4-derived precursor layer transforms into amorphous TiO2, and the TMA-derived precursor layer transforms into amorphous Al2O3, with a conversion rate exceeding 99.5%. The hydroxyl content in the initial film is below the preset atomic percentage threshold of 2 at.%, confirmed quantitatively by X-ray photoelectron spectroscopy (XPS). During oxidation, the substrate temperature is precisely controlled by a back-side helium cooling system with a temperature control accuracy of ±2 °C to prevent thermal degradation of heat-sensitive substrates such as polyimide. After this step, the initial film density reaches ≥3.2 g / cm³ (for TiO2) or ≥3.0 g / cm³ (for Al2O3), the porosity is less than 3%, and a continuous Ti—O—Si or Al—O—Si chemical bond network is formed between the film and the substrate, with a calculated interfacial binding energy of not less than 2.5 eV.

[0034] In the above-described high-adhesion metal oxide coating method, step 4 involves further depositing a main functional metal oxide film layer on the initial film layer. Specifically, a magnetron sputtering process is employed, using a high-purity (≥99.99%) metal target as the sputtering source. The sputtering is carried out in an argon-oxygen mixed atmosphere with an oxygen partial pressure ratio of 5% to 30% (a predetermined proportion), a sputtering power of 100 W to 500 W (a predetermined power value), and a deposition time of 60 s to 600 s (a predetermined time period), forming a main functional film layer with a thickness of 50 nm to 500 nm. The magnetron sputtering system is equipped with a DC or RF power supply, a target-substrate distance of 50 mm to 150 mm, and a working gas pressure of 0.5 Pa to 3 Pa (a predetermined gas pressure value). During deposition, a preset negative bias voltage of -20 V to -100 V is applied to the substrate. This bias voltage is provided by a pulsed DC power supply with a duty cycle of 50% and a frequency of 100 kHz to enhance the surface migration ability of sputtered particles and improve the film density to a predetermined density of over 95%. Target selection is based on the target film composition: pure titanium targets are used for titanium dioxide, pure aluminum targets for aluminum oxide, pure zinc targets for zinc oxide, and In₂O₃:SnO₂ (90:10 wt%) ceramic targets for indium tin oxide (ITO). Oxygen and argon are introduced through independent mass flow controllers, with a total gas flow rate of 20 sccm to 100 sccm. The oxygen partial pressure is monitored in real-time and adjusted in a closed loop using a residual gas analyzer (RGA). During sputtering, the substrate temperature is maintained between 80 °C and 120 °C, controlled by a liquid nitrogen-cooled backplate and an infrared heating lamp. The deposition rate is dynamically adjusted based on the target material and power, typically ranging from 0.1 nm / s to 1 nm / s. The resulting main functional film has a crystal structure of anatase (TiO2), amorphous (Al2O3), or cubic (ITO). The phase structure is controlled by adjusting the sputtering oxygen partial pressure and subsequent annealing temperature: for example, TiO2 forms anatase phase at an oxygen partial pressure of 15% and an annealing temperature of 450 °C, while remaining amorphous at an oxygen partial pressure of 5% and an annealing temperature of 300 °C.

[0035] In the above-mentioned high-adhesion metal oxide coating method, step 5 involves gradient annealing of the composite film. Specifically, the coated substrate is placed in a tube annealing furnace and heated to a preset annealing temperature of 300°C to 500°C at a predetermined heating rate of 2°C / min to 10°C / min, held at that temperature for a predetermined time of 30 min to 120 min, and then cooled to room temperature at a predetermined cooling rate of 1°C / min to 5°C / min to complete the release of interfacial stress and lattice reconstruction. The gradient annealing process is performed in three stages: the heating stage is carried out in an inert nitrogen atmosphere with a nitrogen purity ≥99.999% and an oxygen partial pressure below a preset low oxygen partial pressure threshold of 1 ppm to prevent excessive oxidation of the film during the heating process; the holding stage is switched to an oxygen-containing atmosphere, introducing a mixture of 5% oxygen and 95% nitrogen with an oxygen partial pressure of 5 × 10⁻⁶. 4 A predetermined oxygen partial pressure of Pa promotes the repair of oxygen vacancies at grain boundaries, increasing carrier concentration and optical transmittance. During the cooling phase, the atmosphere is restored to pure nitrogen, and the oxygen partial pressure drops below 1 ppm again to match the difference in thermal expansion coefficients between the substrate and the film, suppressing the formation of thermal stress-induced microcracks. Temperature uniformity within the annealing furnace is controlled within ±3 °C, monitored in real-time by a multi-point thermocouple array. For the polyimide flexible substrate, the upper limit of the annealing temperature is set at 250 °C, and both the heating and cooling rates are set at a low value of 2 °C / min to avoid substrate shrinkage or warping. After this treatment, the interfacial shear strength of the composite film is increased to over 80 MPa, the optical transmittance (at 550 nm wavelength) is greater than or equal to the preset transmittance threshold of 85%, and the film resistivity (for ITO) is reduced to... the following.

[0036] The total thickness of the composite film is within a predetermined range of 50.5 nm to 505 nm, wherein the thickness ratio of the initial film to the main functional film is a predetermined ratio of 1:10 to 1:100. This ratio is achieved by precisely controlling the number of atomic layer deposition cycles and the magnetron sputtering time to ensure maximum interfacial chemical bonding strength while maintaining the optical and electrical properties of the main functional film. For example, when the total thickness is 200 nm, the initial film thickness is 2 nm and the main functional film thickness is 198 nm. At this ratio, the interfacial bonding energy reaches its peak, while the transmittance at a wavelength of 550 nm remains at 87%.

[0037] To verify the feasibility of this method in practical applications, the following specific application scenario was constructed: In the manufacturing of flexible OLED display panels, a 125 μm thick polyimide substrate was used as the substrate. First, step 1 was performed: O2 / Ar = 1:6 (volume ratio) was introduced into a vacuum chamber, with an RF power of 120 W, a processing time of 120 s, and a substrate temperature of 60 ℃, resulting in an activated surface with a water contact angle of 8° and a surface energy of 75 mN / m. Next, step 2 was performed: atomic layer deposition was carried out using TMA and H2O, 30 cycles, with the following sub-step parameters: TMA pulse 0.5 s, purge 15 s, H2O pulse 0.2 s, secondary purge 20 s, and deposition temperature of 150 ℃, forming a 3 nm thick Al precursor layer. Then, step 3 was performed: oxygen plasma treatment was performed at 120 ℃, with a power of 80 W, a time of 180 s, and an electron temperature of 2.2 eV, obtaining a 3 nm thick amorphous Al2O3 initial film with a hydroxyl content of 1.5 at.%. Then, step 4 was performed: magnetron sputtering was carried out using a pure aluminum target, with an oxygen partial pressure of 20%, a sputtering power of 300 W, a substrate bias of -50 V, and a deposition time of 300 s, forming a 197 nm thick Al2O3 main functional film with a density of 96%. Finally, step 5 was performed: gradient annealing was carried out, with a heating rate of 5 ℃ / min to 250 ℃ (nitrogen atmosphere), a holding time of 60 min (switching to 5% O2 / N2), and a cooling rate of 3 ℃ / min (returning to nitrogen atmosphere). The final result was an Al2O3 composite film with a total thickness of 200 nm, a transmittance of 86.5% at 550 nm, and a water vapor transmission rate (WVTR) lower than [value missing]. The adhesion has reached HF-1 level after scratch testing, and the critical load is 45 mN, which meets the requirements for flexible display packaging.

[0038] Example 2

[0039] In another specific application scenario, to address the anti-reflection and passivation requirements of silicon-based photovoltaic cells, p-type monocrystalline silicon wafers are used ( <100> The substrate was selected from the crystal orientation (resistivity 1–3 Ω·cm). Step 1: O2 / Ar = 1:4, RF power 150 W, processing time 90 s, to obtain a surface with a water contact angle of 7°. Step 2: Atomic layer deposition of TiCl4 and H2O was performed, 20 cycles, to form a 2 nm Ti precursor layer. Step 3: Oxygen plasma treatment, power 100 W, time 150 s, 150 ℃, to obtain a 2 nm amorphous TiO2 initial film. Step 4: Pure titanium target magnetron sputtering, oxygen partial pressure 15%, power 400 W, bias voltage -80 V, deposition for 400 s, to form a 398 nm TiO2 main functional film. Step 5: Gradient annealing, heating 8 ℃ / min to 450 ℃ (N2), holding for 90 min (20% O2 / N2), cooling 4 ℃ / min. The final film is anatase TiO2 with a thickness of 400 nm, a transmittance of 88% at 550 nm, a refractive index of 2.45, a surface recombination rate of less than 10 cm / s, and an absolute improvement in cell efficiency of 0.8%.

[0040] Example 3

[0041] For the application of ITO transparent conductive film in touch screens, a soda-lime glass substrate was used. Step 1: O2 / Ar = 1:8, power 100 W, time 60 s. Step 2: Since ITO cannot be directly deposited via ALD, steps 2 and 3 are omitted, and step 4 is performed directly on the activated glass: In2O3:SnO2 ceramic target sputtering, oxygen partial pressure 8%, power 350 W, bias -30 V, deposition for 200 s, forming a 150 nm ITO film. Step 5: Annealing at 350 ℃, heating at 5 ℃ / min, holding at 60 min (10% O2 / N2), cooling at 2 ℃ / min. The resulting film has a sheet resistance of 15 Ω / □, a transmittance of 89% at 550 nm, and a critical adhesion load of 50 mN. This variation demonstrates that when the main functional film layer itself can achieve good adhesion directly through sputtering, the precursor layer construction step can be omitted, but plasma activation and gradient annealing are still retained to optimize performance.

[0042] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for coating a high-adhesion metal oxide film, characterized in that, Includes the following steps: Plasma activation pretreatment is performed on the substrate surface. The substrate to be coated is placed in a vacuum chamber, a mixture of oxygen and argon is introduced, radio frequency power is applied, and the treatment is carried out for a predetermined time period to generate high-density active hydroxyl groups on the substrate surface. A metal precursor layer is deposited on the activated substrate surface using atomic layer deposition (ALD) with titanium tetrachloride or trimethylaluminum as the metal source and water vapor as the oxidant. The layer is deposited cyclically a predetermined number of times under predetermined temperature and pressure conditions to form a metal precursor layer of predetermined thickness. Low-temperature plasma-assisted oxidation of the metal precursor layer is performed. Oxygen plasma is introduced under the condition that the temperature does not exceed the preset upper limit of temperature and the treatment is carried out for a predetermined time period, so that the metal precursor layer is transformed in situ into a dense metal oxide initial film layer. On the initial film layer, a main functional metal oxide film layer is deposited. A magnetron sputtering process is used with a high-purity metal target as the sputtering source. In an argon-oxygen mixed atmosphere, the oxygen partial pressure ratio, sputtering power and deposition time are controlled to form a main functional film layer with a predetermined thickness. The composite film is subjected to gradient annealing. The temperature is raised to a preset annealing temperature at a predetermined heating rate and held at that temperature. Then, it is cooled to room temperature at a predetermined cooling rate to complete the release of interfacial stress and lattice reconstruction.

2. The high-adhesion metal oxide coating method according to claim 1, characterized in that, In the plasma activation pretreatment, the volume ratio of oxygen to argon is 1:4 to 1:9, the radio frequency power is 50 W to 200 W, the treatment time is 30 s to 180 s, the working pressure of the vacuum chamber is 1 Pa to 10 Pa, the water contact angle of the substrate surface is less than 10°, and the surface energy is greater than 72 mN / m.

3. The high-adhesion metal oxide coating method according to claim 1, characterized in that, In the atomic layer deposition process, each deposition cycle includes four sub-steps: a metal source pulse, a first purge, an oxidant pulse, and a second purge. The metal source pulse duration is 0.1 s to 1 s, the first purge duration is 5 s to 20 s, the oxidant pulse duration is 0.05 s to 0.5 s, the second purge duration is 10 s to 30 s, the deposition temperature is 100 ℃ to 250 ℃, the chamber pressure is 0.1 Torr to 1 Torr, and the number of cycles is 5 to 50.

4. The high-adhesion metal oxide coating method according to claim 1, characterized in that, During the low-temperature plasma-assisted oxidation process, the processing temperature does not exceed 150 °C, the plasma power is 30 W to 150 W, the processing time is 60 s to 300 s, the plasma electron temperature is 1.5 eV to 3.0 eV, and the hydroxyl content in the initial film is less than 2 at.%.

5. The method for high adhesion metal oxide coating according to claim 1, characterized in that, In the magnetron sputtering process, the oxygen partial pressure ratio is 5% to 30%, the sputtering power is 100 W to 500 W, the deposition time is 60 s to 600 s, the target-substrate distance is 50 mm to 150 mm, the working gas pressure is 0.5 Pa to 3 Pa, and a negative bias voltage of -20 V to -100 V is applied to the substrate.

6. The method for high adhesion metal oxide coating according to claim 1, characterized in that, In the gradient annealing process, the heating rate is 2 ℃ / min to 10 ℃ / min, the annealing temperature is 300 ℃ to 500 ℃, the holding time is 30 min to 120 min, and the cooling rate is 1 ℃ / min to 5 ℃ / min. The heating and cooling stages are carried out in an inert nitrogen atmosphere, and the holding stage is carried out in an oxygen-containing atmosphere.

7. The method for high adhesion metal oxide coating according to claim 1, characterized in that, The main functional metal oxide film is titanium dioxide, aluminum oxide, zinc oxide or indium tin oxide, and its crystal structure is anatase, amorphous or cubic phase. The phase structure is controlled by adjusting the sputtering oxygen partial pressure and annealing temperature.

8. The method for high adhesion metal oxide coating according to claim 1, characterized in that, The total thickness of the composite film is 50.5 nm to 505 nm, and the thickness ratio of the initial film to the main functional film is 1:10 to 1:

100. This ratio ensures that the interfacial chemical bonding strength is maximized and the optical transmittance of the main functional film is not less than 85%.

9. The method for high adhesion metal oxide coating according to claim 1, characterized in that, The substrate is a silicon wafer, glass, stainless steel, or polyimide flexible substrate. When the substrate is a curved surface or a three-dimensional microstructure, uniform processing is achieved through a rotating support system during plasma activation, deposition, and annealing, and the film thickness uniformity deviation is less than the preset tolerance.

10. The method for high adhesion metal oxide coating according to claim 1, characterized in that, When the main functional film layer is indium tin oxide, the metal precursor layer deposition and low-temperature plasma-assisted oxidation steps are omitted. Magnetron sputtering deposition is performed directly on the plasma-activated substrate, followed by gradient annealing.

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