A substrate interface pretreatment method for anisotropic magnetoresistance film deposition

Abstract

This invention discloses a substrate interface pretreatment method for anisotropic magnetoresistive thin film deposition, belonging to the field of pre-deposition processing technology for thin film deposition. The method includes: (1) wiping the substrate surface with dilute hydrofluoric acid; (2) placing the substrate into a deposition chamber and evacuating it to a vacuum level ≤1×10⁻⁶. ‑6 Torr; (3) Introduce a protective atmosphere and perform a stepwise heating treatment on the substrate, including at least three steps: 100 ℃, 300 ℃, and 500 ℃. Hold each step for 20 min to 30 min to allow hydrofluoric acid to remove the oxide layer in situ and activate the surface; (4) Cool down to room temperature, stop the gas supply, and evacuate. This invention uses a synergistic process of wiping with dilute hydrofluoric acid and stepwise heating in the chamber to sequentially complete the removal of physically adsorbed water, selective reaction of the oxide layer, and activation of surface polarization bonds. The average thickness of the remaining oxide layer is ≤5 nm, and the density of surface active polarization bonds is increased by more than 10 times. The entire process is carried out in situ to avoid secondary contamination and significantly enhances the adhesion and crystal quality of the subsequently deposited film.

Description

Technical Field

[0001] This invention relates to the field of pretreatment processes for thin film deposition, specifically an in-situ substrate interface pretreatment method for thin film deposition, suitable for preparing anisotropic magnetoresistive manganese oxide thin films with strong adhesion and high service stability. Background Technology

[0002] In thin film deposition processes, the substrate surface condition is one of the key factors determining the nucleation mode, growth orientation, interfacial adhesion, and final device performance. An ideal substrate surface should be atomically clean and chemically active to enable epitaxial or preferentially oriented thin film growth. However, widely used commercial substrates such as silicon-based, silicon nitride-based, silicon oxide-based, and mica substrates inevitably develop natural oxide layers and adsorb environmental impurities during storage and transfer. These surface contamination layers not only passivate nucleation centers, leading to a decrease in thin film crystallinity, but also create defects at the interfaces, causing cracking, warping, and even detachment of the film under temperature changes or external stress, severely impairing device stability and lifespan.

[0003] Traditional substrate pretreatment is typically performed outside the deposition chamber, such as wet cleaning with organic solvents or strong acids before being transferred into the chamber. This approach has the following inherent drawbacks: First, during the transfer process after cleaning, the substrate is exposed to the atmosphere again, and re-adsorption and re-oxidation can occur within seconds, making it impossible to guarantee a truly clean surface. Second, conventional cleaning relies heavily on chemical etching, making it difficult to precisely control the depth of oxide layer removal, which can easily cause surface damage or residue. Third, the lack of an effective in-situ activation step makes it difficult to provide a highly active growth interface instantly before deposition, limiting the bonding strength of the initial thin film layer.

[0004] Therefore, there is an urgent need for a pretreatment method that can be highly integrated with the deposition chamber, efficiently remove the oxide layer on the substrate surface, and achieve in-situ surface activation. Summary of the Invention

[0005] The purpose of this invention is to provide a substrate interface pretreatment method for anisotropic magnetoresistive thin film deposition, so as to solve the technical problems of secondary contamination, incomplete oxide layer removal, and insufficient surface activation in the substrate pretreatment of the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A substrate interface pretreatment method for anisotropic magnetoresistive thin film deposition includes the following steps: (1) Provide a substrate and wipe the surface of the substrate with dilute hydrofluoric acid; (2) Place the wiped substrate into the deposition chamber and evacuate the chamber to a background vacuum of ≤1×10⁻⁶. -6 Torr; (3) A protective atmosphere is introduced into the cavity, and the substrate is subjected to a stepped heating process under the atmosphere. The temperature steps include at least a first temperature step of 100 ℃, a second temperature step of 300 ℃ and a third temperature step of 500 ℃. The temperature is maintained at each temperature step for 20 min to 30 min, so that hydrofluoric acid reacts in situ with the oxide layer on the substrate surface at high temperature to remove the oxide layer and activate the surface. (4) After the reaction is complete, gradually lower the substrate temperature to room temperature, then stop the protective atmosphere and evacuate the chamber again to ≤1×10 -6 Torr is used to obtain the substrate after interface pretreatment.

[0007] Preferably, in step (1), the concentration of dilute hydrofluoric acid is 0.5%~2%, and the wiping time is 3 min~10 min; the wiping operation involves using a dust-free paper dipped in dilute hydrofluoric acid to thoroughly and gently wipe the substrate surface.

[0008] Preferably, the substrate in step (1) is selected from SiN. δ One of Si or mica; the SiN δ The substrate thickness is 40 μm to 10000 μm, and δ = 1.00 to 1.33; the Si substrate thickness is 20 μm to 10000 μm, and the crystal plane index is [missing value]. <100> , <111> or <110> The type is P-type or N-type; the mica substrate is natural muscovite or fluorinated mica, with a thickness of 100 μm to 10000 μm and a surface roughness of ≤0.5 nm.

[0009] Preferably, when the substrate is SiN δ When the substrate is a Si substrate, the concentration of dilute hydrofluoric acid is preferably 1.0% to 2.0%; when the substrate is a mica substrate, the concentration of dilute hydrofluoric acid is preferably 1.5% to 2.0%; when the substrate is a mica substrate, the concentration of dilute hydrofluoric acid is preferably 0.5% to 1.0%.

[0010] Preferably, in step (3), the heating rate of the stepped heating is 5 ℃ / min to 50 ℃ / min; wherein, when the substrate is a mica substrate, the heating rate is preferably 5 ℃ / min to 15 ℃ / min.

[0011] Preferably, in step (4), the cooling rate of the substrate temperature is 5 ℃ / min to 30 ℃ / min; wherein, when the substrate is a mica substrate, the cooling rate is preferably 5 ℃ / min to 10 ℃ / min.

[0012] Preferably, in step (3), the protective atmosphere introduced is high-purity argon gas with a purity ≥ 99.99%.

[0013] Preferably, in step (3), the first temperature step of 100 ℃ is held for 25 min to 30 min to remove physically adsorbed water on the substrate surface; the second temperature step of 300 ℃ is held for 25 min to 30 min to remove chemically adsorbed impurities and thermally decompose residual acid radicals; and the third temperature step of 500 ℃ is held for 20 min to 25 min to activate the polarization bonds on the substrate surface and form highly activated surface states.

[0014] Preferably, the synergistic effect of steps (1) and (3) is as follows: a trace amount of dilute hydrofluoric acid is pre-attached to the micro-defects of the oxide layer on the substrate surface during the room temperature wiping process. In the subsequent stepwise heating process, the activity of hydrofluoric acid gradually increases with the temperature, and successively goes through the surface diffusion and penetration stage at 100 ℃, the selective reaction stage with the oxide layer at 300 ℃, and the reaction product volatilization and surface activation stage at 500 ℃, so as to achieve the gradual and precise peeling of the oxide layer.

[0015] Preferably, after treatment by the pretreatment method, the average thickness of the remaining oxide layer on the substrate surface is ≤5 nm, and the surface active polarization bond density is more than 10 times higher than that of the untreated substrate.

[0016] Preferably, the entire process from step (1) to step (4) is completed in situ within the deposition chamber. From the time the substrate is wiped with dilute hydrofluoric acid until the start of film deposition, it is not exposed to the atmospheric environment, thus avoiding secondary oxidation and re-contamination during the "processing-transfer" process.

[0017] Preferably, the method further includes a thin film deposition step after step (4), wherein the thin film is an anisotropic magnetoresistive thin film, and the substrate is heated to a temperature of 200 ℃ to 800 ℃ during the thin film deposition process.

[0018] The present invention also provides a method for SiN δ The substrate interface pretreatment method includes the following steps: (1) Provide a SiN δ The substrate surface was wiped with a 1.0% to 2.0% dilute hydrofluoric acid solution for 5 to 10 minutes. (2) Place the wiped substrate into the deposition chamber and evacuate the chamber to a background vacuum of ≤1×10⁻⁶. -6 Torr; (3) High-purity argon gas with a purity of ≥99.99% is introduced into the cavity as a protective atmosphere, and the substrate is heated to 100 ℃ for 25 min to 30 min, 300 ℃ for 25 min to 30 min, and 500 ℃ for 20 min to 25 min at a heating rate of 20 ℃ / min to 50 ℃ / min. (4) Cool the substrate to room temperature at a cooling rate of 15 ℃ / min~30 ℃ / min, stop the argon gas supply, and evacuate the cavity again to a vacuum of ≤1×10 -6 Torr yielded SiN with a residual oxide layer thickness ≤ 5 nm and surface activation. δ Substrate.

[0019] This invention also provides an interface pretreatment method for fluorine-crystalline mica substrates, comprising the following steps: (1) Provide a fluorine crystal mica substrate with a surface roughness ≤0.5 nm, and gently wipe the substrate surface with a dilute hydrofluoric acid concentration of 0.5%~1.0% for 8 min~10 min; (2) Place the wiped substrate into the deposition chamber and evacuate the chamber to a background vacuum of ≤1×10⁻⁶. -6 Torr; (3) High-purity argon gas with a purity of ≥99.99% is introduced into the cavity as a protective atmosphere, and the substrate is heated to 100 ℃ for 30 min, 300 ℃ for 30 min, and 500 ℃ for 30 min at a heating rate of 5 ℃ / min to 15 ℃ / min. (4) Cool the substrate to room temperature at a cooling rate of 5 ℃ / min~10 ℃ / min, stop the argon gas supply, and evacuate the cavity again to a vacuum of ≤1×10 -6 Torr yielded a fluorinated mica substrate with a remaining oxide layer thickness ≤ 5 nm and surface activation.

[0020] This invention also provides an interface pretreatment method for fluorine-crystalline mica substrates, comprising the following steps: (1) Provide a fluorine crystal mica substrate with a surface roughness ≤0.5 nm, and gently wipe the substrate surface with a dilute hydrofluoric acid concentration of 0.5%~1.0% for 8 min~10 min; (2) Place the wiped substrate into the deposition chamber and evacuate the chamber to a background vacuum of ≤1×10⁻ 6 Torr; (3) High-purity argon gas with a purity of ≥99.99% is introduced into the cavity as a protective atmosphere, and the substrate is heated to 100 ℃ for 30 min, 300 ℃ for 30 min, and 500 ℃ for 30 min at a heating rate of 5 ℃ / min to 15 ℃ / min. (4) Cool the substrate to room temperature at a cooling rate of 5 ℃ / min~10 ℃ / min, stop the argon gas supply, and evacuate the cavity again to a vacuum of ≤1×10⁻ 6 Torr yielded a fluorinated mica substrate with a remaining oxide layer thickness ≤ 5 nm and surface activation.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention creatively employs an in-situ treatment process that combines “dilute hydrofluoric acid surface wiping” with “stepwise heating and heat preservation in the deposition chamber”. Trace amounts of hydrofluoric acid undergo in-situ gas-phase reaction or surface chemical reaction with the natural oxide layer on the substrate surface at high temperature, which can precisely etch it to a thickness of ≤5 nm. At the same time, thermal desorption removes organic impurities, achieving atomic-level clean treatment of the substrate surface before deposition.

[0022] (2) The method of the present invention, under a protective high-purity argon atmosphere, through a multi-step heat preservation mode of 100 ℃, 300 ℃, and 500 ℃, not only removes adsorbed water and residual acid radicals, but also activates the polarization bonds on the substrate surface at the end of the high-temperature steps, forming a highly activated surface state. This activated surface has a very strong chemical affinity for the subsequent plasma plume of magnetoresistive manganese oxide, which can significantly promote uniform high-density nucleation and greatly enhance the interfacial adhesion between the film and the substrate.

[0023] (3) The entire process of this invention is completed in situ within the thin film deposition chamber, completely eliminating secondary pollution during the “processing-transfer” process and ensuring uninterrupted and continuous operation from surface activation to thin film growth. As a result, the final composite thin film has a low interface defect density and the internal stress is effectively released, fundamentally solving the long-term service reliability problems such as film detachment and cracking caused by weak interface bonding.

[0024] (4) The present invention optimizes the combination of parameters such as dilute hydrofluoric acid concentration, heating and cooling rate and holding time for different substrate materials, which not only ensures the effective removal of oxide layer, but also avoids excessive corrosion or thermal damage to substrate surface, thus broadening the applicability of the method to different substrate systems. Attached Figure Description

[0025] To more clearly illustrate the technical solutions involved in the embodiments of the present invention or the prior art, the accompanying drawings included in the description of the embodiments or the prior art will be briefly introduced below. It should be noted that these drawings only show some specific embodiments recorded in the present invention and do not cover all possible implementations.

[0026] Figure 1 The pretreated SiN in Example 1 δ Atomic force microscope image of the substrate; Figure 2 The X-ray diffraction pattern of the fluorine crystal mica substrate after pretreatment in Example 3; Figure 3 The SiN pretreated with 2.0% dilute hydrofluoric acid in Example 4. δ Scanning microscope image of the substrate; Figure 4The image shows the X-ray diffraction pattern of the pretreated natural muscovite substrate in Example 5. Detailed Implementation

[0027] The technical solution of the present invention will now be described in detail and comprehensively. It should be noted that the embodiments described are only a part of the present invention and do not cover all embodiments. Furthermore, all other embodiments that can be obtained by those skilled in the art based on the embodiments provided by the present invention without creative effort should also fall within the protection scope of the present invention. In the following embodiments, unless otherwise specified, the instruments and materials used are commercially available.

[0028] Example 1: This example applies to SiN δ The substrate undergoes interface pretreatment for subsequent deposition of high-entropy manganese oxide polycrystalline composite films.

[0029] (1) Substrate preparation. SiN is selected. δ Substrate, δ=1.10, thickness 200 μm, area 1 cm² 2 The square. Using a lint-free paper soaked in a 1% dilute hydrofluoric acid solution, gently and evenly wipe the entire substrate surface for 5 minutes, so that a trace amount of hydrofluoric acid is pre-adhered to the micro-defects in the natural oxide layer on the substrate surface.

[0030] (2) Cavity loading and vacuuming. Immediately load the wiped substrate into the pulsed laser deposition cavity, close the cavity door, and start the vacuuming process to achieve a base vacuum of 8 × 10⁻⁶. -7 Torr. This step ensures that the substrate remains completely unexposed to the atmosphere after being wiped with dilute hydrofluoric acid.

[0031] (3) Argon gas introduction and stepped heating. High-purity argon gas with a purity of 99.999% was continuously introduced into the cavity as a protective atmosphere. The substrate was gradually heated to 100 ℃ at a heating rate of 30 ℃ / min and held for 25 min; then heated to 300 ℃ at the same rate and held for 25 min; finally heated to 500 ℃ at 20 ℃ / min and held for 20 min. During the step-by-step heating process, the trace amounts of hydrofluoric acid remaining on the substrate surface reacted with the natural oxide layer to generate volatile fluorides, which were carried away by the gas flow. At the same time, thermal desorption removed the impurities adsorbed on the surface.

[0032] (4) Cooling and obtaining the activated surface. After the holding process is completed, the substrate temperature is gradually reduced to room temperature at a cooling rate of 15 °C / min. The high-purity argon gas is stopped, and the cavity is evacuated again to a vacuum of 5 × 10⁻⁶. -7 Torr, that is, SiN after interface pretreatment δ Substrate.

[0033] Atomic force microscopy characterization revealed that the average thickness of the remaining oxide layer on the substrate surface was 3.5 nm, and the surface exhibited a highly activated state. This embodiment shows that the pretreated SiN... δ Atomic force microscopy image of the substrate as shown Figure 1 As shown.

[0034] Example 2: This example applies to P-type Si <100> The substrate undergoes interface pretreatment.

[0035] (1) Substrate preparation. P-type Si is selected. <100> Substrate, resistivity 1 Ω·cm~10 Ω·cm, thickness 400 μm, area 0.25 cm². 2 The substrate is circular. Wipe the substrate surface with a 2% dilute hydrofluoric acid solution using a lint-free paper towel for 3 minutes.

[0036] (2) Cavity loading and vacuuming. Immediately load the wiped substrate into the pulsed laser deposition cavity, close the cavity door, and start the vacuuming process to achieve a base vacuum of 8 × 10⁻⁶. -7 Torr. This step ensures that the substrate remains completely unexposed to the atmosphere after being wiped with dilute hydrofluoric acid.

[0037] (3) Argon gas introduction and stepped heating. High-purity argon gas with a purity of 99.999% was continuously introduced into the cavity as a protective atmosphere. The substrate was gradually heated to 100 ℃ at a heating rate of 50 ℃ / min and held for 30 min; then heated to 300 ℃ at the same rate and held for 30 min; then heated to 500 ℃ and held for 30 min. During the step-heating process, the trace amounts of hydrofluoric acid remaining on the substrate surface reacted with the natural oxide layer to generate volatile fluorides, which were carried away by the gas flow. At the same time, thermal desorption removed the impurities adsorbed on the surface.

[0038] (4) Cooling and obtaining the activated surface. After the holding process is completed, the substrate temperature is gradually reduced to room temperature at a cooling rate of 30 °C / min. The high-purity argon gas is stopped, and the cavity is evacuated again to a vacuum of 5 × 10⁻⁶. -7 Torr, that is, SiN after interface pretreatment δ Substrate.

[0039] After treatment in this embodiment, the average thickness of the remaining oxide layer on the Si substrate surface is 2.1 nm, and the surface silicon polarization bond density is significantly increased.

[0040] Example 3: This example demonstrates interface pretreatment of a fluorine crystal mica substrate.

[0041] (1) Substrate preparation. A fluorinated mica substrate with a thickness of 500 μm, a surface roughness of 0.3 nm, and a size of 4 cm² was selected. The surface was gently wiped for 10 min with a 0.5% dilute hydrofluoric acid solution using a lint-free paper. Since mica has a layered silicate structure, a low concentration of hydrofluoric acid can effectively remove surface adsorbates and a slight hydration layer.

[0042] (2) Place the wiped substrate into the deposition chamber and evacuate the chamber to a background vacuum of ≤1×10⁻⁶. -6 Torr; (3) High-purity argon gas with a purity of ≥99.99% is introduced into the cavity as a protective atmosphere. The substrate is heated to 100 ℃ for 30 min, 300 ℃ for 30 min, and 500 ℃ for 30 min at a heating rate of 5 ℃ / min. The heating rate of 5 ℃ / min is to prevent interlayer cracking of mica due to the anisotropy of thermal expansion coefficient. (4) Cool the substrate to room temperature at a cooling rate of 5 °C / min, and slowly cool it to maintain the flatness of the mica. Stop the argon gas supply and evacuate the cavity again to a vacuum of ≤1×10⁻⁶. -6 Torr yielded a fluorinated mica substrate with a remaining oxide layer thickness ≤ 5 nm and surface activation.

[0043] After pretreatment in this embodiment, the surface roughness of the mica substrate remained at 0.35 nm, the remaining contamination layer thickness was ≤5 nm, and the content of surface-active polarization bonds was significantly increased. The X-ray diffraction pattern of the fluorine-crystal mica substrate after pretreatment in this embodiment is shown below. Figure 2 As shown.

[0044] Example 4: To verify the effect of different hydrofluoric acid concentrations on the pretreatment effect in this invention, this example uses dilute hydrofluoric acid with concentrations of 0.5%, 1.0%, and 2.0% to pretreat SiN. δ The substrate is pretreated, and the remaining steps are the same as in Example 1.

[0045] The results showed that with increasing hydrofluoric acid concentration, the thickness of the remaining oxide layer decreased from 4.8 nm (0.5% concentration group) to 1.5 nm (2.0% concentration group). However, slight pitting appeared on the surface of the 2.0% concentration group. Pretreatment of SiN with 2.0% dilute hydrofluoric acid... δ Scanning microscope image of the substrate as shown Figure 3 As shown. Considering both surface cleanliness and integrity, the 1.0% concentration group (with a remaining oxide layer of 3.5 nm and no surface damage) is the preferred option. This demonstrates that the concentration range set in this invention combines effectiveness and material compatibility. When the substrate is SiN... δ When using a substrate, the concentration of dilute hydrofluoric acid is preferably 1.0% to 2.0%.

[0046] Example 5: This example demonstrates interface pretreatment of a natural muscovite substrate.

[0047] (1) Substrate preparation and wiping with dilute hydrofluoric acid. A natural mica substrate with a thickness of 800 μm, a surface roughness of 0.4 nm, and a size of 6 cm² was selected. 2 Use a lint-free paper towel soaked in a 0.8% dilute hydrofluoric acid solution to gently wipe the surface for 10 minutes.

[0048] (2) Cavity loading and vacuuming. Same as in Example 1.

[0049] (3) Propagate a protective atmosphere and raise the temperature in stages. Raise the substrate to 100℃ for 30 min, 300℃ for 30 min, and 500℃ for 30 min at a heating rate of 10℃ / min.

[0050] (4) Cooling and obtaining an activated surface. The substrate was cooled to room temperature at a cooling rate of 8 °C / min, and the rest was the same as in Example 1.

[0051] In this embodiment, the natural muscovite contains a small amount of structural water, and its heating rate is slightly higher than that of fluorinated mica but still much lower than that of the Si-based substrate. The surface roughness after pretreatment is 0.42 nm, and the remaining contamination layer thickness is 4.8 nm. The X-ray diffraction pattern of the pretreated natural muscovite substrate in this embodiment is shown below. Figure 4 As shown.

[0052] Example 6: To verify the pretreatment effect, anisotropic magnetoresistive thin films were deposited on the substrates treated in Examples 1-3 using pulsed laser deposition. Deposition conditions: oxygen pressure 15 Pa, substrate temperature 650 ℃, energy density 1.5 J / cm², pulse number 5000 pulses.

[0053] The resulting film bonded well to the substrate, with no detachment or cracking observed. X-ray diffraction patterns showed that the film grew with good preferred orientation, proving that the interface pretreatment method of this invention effectively improved the nucleation and growth quality of the film.

[0054] The technical solutions of this invention are not limited to the specific embodiments described above. Any technical modifications, alterations, substitutions, and variations made to the technical solutions of this invention without departing from the spirit and scope of the claims are within the protection scope of this invention.

Claims

1. A substrate interface pretreatment method for anisotropic magnetoresistive thin film deposition, characterized in that, Includes the following steps: (1) Provide a substrate and wipe the surface of the substrate with dilute hydrofluoric acid; (2) Place the wiped substrate into the deposition chamber and evacuate the chamber to a background vacuum of ≤1×10⁻⁶. -6 Torr; (3) A protective atmosphere is introduced into the cavity, and the substrate is subjected to a stepped heating process under the atmosphere. The temperature steps include at least a first temperature step of 100 ℃, a second temperature step of 300 ℃ and a third temperature step of 500 ℃. The temperature is maintained at each temperature step for 20 min to 30 min, so that hydrofluoric acid reacts in situ with the oxide layer on the substrate surface at high temperature to remove the oxide layer and activate the surface. (4) After the reaction is complete, gradually lower the substrate temperature to room temperature, then stop the protective atmosphere and evacuate the chamber again to ≤1×10 -6 Torr, to obtain the substrate after interface pretreatment.

2. The substrate interface pretreatment method according to claim 1, characterized in that, In step (1), the concentration of dilute hydrofluoric acid is 0.5%~2%, and the wiping time is 3 min~10 min; the wiping operation involves using a dust-free paper dipped in dilute hydrofluoric acid to thoroughly and gently wipe the substrate surface.

3. The substrate interface pretreatment method according to claim 1, characterized in that, The substrate in step (1) is selected from SiN δ One of Si or mica; the SiN δ The substrate thickness is 40 μm to 10000 μm, and δ = 1.00 to 1.33; the Si substrate thickness is 20 μm to 10000 μm, and the crystal plane index is [missing value]. <100> , <111> or <110> The type is P-type or N-type; the mica substrate is natural muscovite or fluorinated mica, with a thickness of 100 μm to 10000 μm and a surface roughness of ≤0.5 nm.

4. The substrate interface pretreatment method according to claim 3, characterized in that, When the substrate is SiN δ When the substrate is a Si substrate, the concentration of dilute hydrofluoric acid is preferably 1.0% to 2.0%; when the substrate is a mica substrate, the concentration of dilute hydrofluoric acid is preferably 1.5% to 2.0%; when the substrate is a mica substrate, the concentration of dilute hydrofluoric acid is preferably 0.5% to 1.0%.

5. The substrate interface pretreatment method according to claim 1, characterized in that, In step (3), the heating rate of the stepped heating is 5 ℃ / min to 50 ℃ / min; wherein, when the substrate is a mica substrate, the heating rate is preferably 5 ℃ / min to 15 ℃ / min.

6. The substrate interface pretreatment method according to claim 1, characterized in that, In step (4), the cooling rate of the substrate temperature is gradually reduced from 5 ℃ / min to 30 ℃ / min; wherein, when the substrate is a mica substrate, the cooling rate is preferably 5 ℃ / min to 10 ℃ / min.

7. The substrate interface pretreatment method according to claim 1, characterized in that, In step (3), the protective atmosphere introduced is high-purity argon gas with a purity ≥99.99%.

8. The substrate interface pretreatment method according to claim 1, characterized in that, In step (3), the first temperature step of 100 ℃ is held for 25 min to 30 min to remove physically adsorbed water on the substrate surface; the second temperature step of 300 ℃ is held for 25 min to 30 min to remove chemically adsorbed impurities and thermally decompose residual acid radicals; the third temperature step of 500 ℃ is held for 20 min to 25 min to activate the polarization bonds on the substrate surface and form highly activated surface states.

9. The substrate interface pretreatment method according to claim 1, characterized in that, After treatment by the aforementioned pretreatment method, the average thickness of the remaining oxide layer on the substrate surface is ≤5 nm, and the surface active polarization bond density is increased by more than 10 times compared with the untreated substrate.

10. A substrate interface pretreatment method for thin film deposition, characterized in that, Includes the following steps: (1) Provide a SiN δ The substrate surface was wiped with a 1.0% to 2.0% dilute hydrofluoric acid solution for 5 to 10 minutes. (2) Place the wiped substrate into the deposition chamber and evacuate the chamber to a background vacuum of ≤1×10⁻⁶. -6 Torr; (3) Introduce high-purity argon gas with a purity of ≥99.99% into the cavity as a protective atmosphere, and heat the substrate sequentially to 100℃ for 25 min to 30 min, 300℃ for 25 min to 30 min, and 500℃ for 20 min to 25 min at a heating rate of 20 ℃ / min to 50 ℃ / min. (4) Cool the substrate to room temperature at a cooling rate of 15 ℃ / min~30 ℃ / min, stop the argon gas supply, and evacuate the cavity again to a vacuum of ≤1×10 -6 Torr yielded SiN with a residual oxide layer thickness ≤ 5 nm and surface activation. δ Substrate.

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