A high-temperature-resistant nano-composite ceramic coating and a preparation method thereof

Abstract

The application relates to the technical field of ceramic coating, and discloses a high-temperature-resistant nano composite ceramic coating and a preparation method thereof, which comprises 15-18 parts of nano, 25-30 parts of nano, 10-12 parts of modified nano, 3-5 parts of nano, 35-40 parts of acidic silicon solution, 2-3 parts of nano and 1-2 parts of nano SiC. The high-temperature-resistant nano composite ceramic coating has excellent high-temperature resistance, chemical corrosion resistance and thermal shock resistance; the obtained composite ceramic coating is firmly combined with a base material; the preparation method has high controllability; and the method is suitable for the high-precision requirement of semiconductors.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic coating, in particular to a high-temperature-resistant nano-composite ceramic coating and a preparation method thereof. BACKGROUND

[0002] Ceramic coating is a general term for inorganic non-metallic coatings, which refers to a sprayed layer whose material is ceramic. Its composition includes oxide coatings, non-oxide coatings, silicate coatings, and composite ceramic coatings. Ceramic coatings have many properties, such as wear resistance, corrosion resistance, anti-sticking, high-temperature resistance, and good biocompatibility. These properties make ceramic coatings widely used in many fields. For example, in aero-engines, ceramic coatings can improve the high-temperature strength and corrosion resistance of turbine blades, thereby improving the performance of the engine. In the field of spaceflight, ceramic coatings can be used to protect important components of spacecraft, improve the reliability and life of spacecraft. In addition, ceramic coatings can also be used in the fields of automobile manufacturing, mechanical manufacturing, military industry, etc., to improve the performance and life of products.

[0003] During the use of semiconductor production equipment, the surface of the rack module and other structures needs to be coated with a ceramic coating to provide high-strength protection, high-temperature resistance, and chemical corrosion resistance, protect the equipment, improve the reliability of the equipment, and improve the thermal efficiency of the equipment. Under normal circumstances, a single ceramic coating cannot well meet the use requirements. When the coating substrate is heated and expands during the semiconductor production process, the single coating is prone to cracking and even large pieces of the coating fall off under thermal stress. Therefore, it is of great practical significance to propose a preparation method and process for a high-temperature-resistant nano-composite ceramic coating. SUMMARY

[0004] In view of this, the present application proposes a high-temperature-resistant nano-composite ceramic coating and a preparation method thereof, aiming to solve at least one of the problems in the background art.

[0005] The present application proposes a high-temperature-resistant nano-composite ceramic coating, which comprises the following components by mass fraction:

[0006] 15-18 parts of nano , 25-30 parts of nano , 10-12 parts of modified nano , 3-5 parts of nano , 35-40 parts of acidic silicon solution, 2-3 parts of nano , and 1-2 parts of nano SiC.

[0007] Preferably, the modified nano SiO2 is obtained by the following method:

[0008] Add 2-5 wt.% of nano , high speed stirring for 10-15 min, and then ultrasonic treatment for 20-30 min, to obtain a mixed solution;

[0009] Then, the mixed solution is placed in a high speed centrifuge, and after centrifugation at a speed of 5000 r / min for 10 min, the activated nano-SiO2 is obtained by washing and centrifugation with ethanol for 2-5 times. ;

[0010] The activated nano-SiO2 is placed in a hydrochloric acid solution with a pH value of 4-5, and after mixing, a second mixed solution is obtained.

[0011] The silane coupling agent is placed in the second mixed solution for reaction, and after stirring for 3-4 h, the modified nano-SiO2 is obtained by washing and centrifugation with ethanol for 2-5 times, and finally drying in an atmosphere at a temperature of 105-120℃ for 2 h. .

[0012] The application also provides a preparation method of the high-temperature-resistant nano-composite ceramic coating.

[0013] Substrate pretreatment: cleaning the surface of the substrate, and then ultrasonic cleaning and drying the substrate, and surface activation treatment of the substrate to obtain a pretreated substrate.

[0014] Material preparation: preparing ceramic coating raw material components, and mixing the ceramic coating raw material components in proportion to prepare a coating slurry.

[0015] Coating preparation: in a constant temperature and humidity environment, the coating slurry is sprayed on the surface of the substrate by layering gradient spraying to obtain a substrate with a coating.

[0016] Coating post-treatment: after drying treatment of the substrate with a coating, sintering treatment is performed to obtain a sintered high-temperature-resistant nano-composite ceramic coating based on a graphite surface.

[0017] Strengthening treatment: the surface of the sintered high-temperature-resistant nano-composite ceramic coating based on a graphite surface is subjected to strengthening treatment by plasma surface treatment to obtain the high-temperature-resistant nano-composite ceramic coating based on a graphite surface.

[0018] Preferably, the substrate is a graphite material, the surface of the substrate is cleaned by mechanical polishing, which specifically includes removing oil stains, impurities and oxides on the surface; the parameters of the ultrasonic cleaning are as follows: frequency 20-40 kHz, power 150-300 W, cleaning time 15-30 minutes, and the cleaning medium of the ultrasonic cleaning is anhydrous ethanol or deionized water; the parameters of the drying are as follows: temperature 105-120℃, and time 2 h.

[0019] Preferably, the activation treatment specifically comprises: immersing the dried substrate into a 5% dilute nitric acid solution at 60℃ for 30min, then taking out for cleaning, vacuum drying at 105℃ for 1h, and finally transferring into a sealed container under inert gas protection for standby.

[0020] Preferably, the gradient spraying specifically comprises: spraying 1-2 layers of primer with low flow rate to form a transition layer with a thickness of 5-10μm, spraying 2-3 layers of intermediate layer with medium flow rate, with a thickness of 10-15μm, and spraying 1 layer of surface layer with high flow rate, with a thickness of 5μm, and performing infrared pre-drying after each layer of spraying, wherein the infrared pre-drying temperature is 80℃, and the time is 3min.

[0021] Preferably, the nozzle flow rate of the low flow rate spraying is 10mL / min, and the distance is 50cm; the nozzle flow rate of the medium flow rate spraying is 15mL / min, and the distance is 40cm; and the nozzle flow rate of the high flow rate spraying is 20mL / min, and the distance is 30cm.

[0022] Preferably, the drying treatment in the coating post-treatment specifically comprises: placing the coated substrate into an oven at 105-120℃ for drying, and the time is 2h; and the sintering treatment specifically comprises: placing the coated substrate into a heating furnace, and increasing the temperature to 800-1050℃ at a heating rate of 5℃ / min, and keeping the temperature for 2-3h, and finally cooling to room temperature with the furnace.

[0023] Preferably, the plasma surface treatment specifically comprises: performing 3min plasma bombardment on the coating surface in an argon atmosphere, and the power of the plasma bombardment is 500W, and the gas pressure is 10Pa.

[0024] The application also provides an application of the high-temperature-resistant nano-composite ceramic coating in semiconductor production, and the high-temperature-resistant nano-composite ceramic coating based on a graphite surface is the nano-composite ceramic coating as described in the above technical solutions.

[0025] Compared with the prior art, the application has the following beneficial effects:

[0026] (1) excellent high-temperature resistance: the nano , , in the coating composition all have good high-temperature resistance, and in combination with sintering at 800-1050℃ and plasma strengthening treatment, the coating can maintain structural stability in a high-temperature environment (such as a high-temperature working condition in semiconductor production), without obvious cracking, falling off or weight loss, and is suitable for long-term high-temperature operation requirements of equipment.

[0027] (2) strong chemical corrosion resistance: the modified nano Optimize coating density, plasma treatment further seals the surface layer of the hole, so that the coating can resist hydrochloric acid, sodium hydroxide and semiconductor special cleaning fluid and other corrosive media, avoid corrosion medium penetration damage substrate, meet the semiconductor production chemical protection requirements.

[0028] (3) The coating is firmly combined with the substrate: the substrate is activated by dilute nitric acid to generate active groups, and the modified nano Play the role of "interface bridge", hierarchical gradient spraying builds transition layer to buffer thermal stress, and finally the coating has high bonding strength (pull-off strength ≥ 8.5 MPa, grid 0 level), which can resist external force and thermal shock in the operation of the equipment and reduce the risk of coating falling off.

[0029] (4) Outstanding thermal shock resistance: the hierarchical gradient structure balances the difference in thermal expansion coefficient between graphite and coating, and the plasma treatment repairs the surface microcracks. The coating still has no cracking after 50 cycles of "800℃-25℃ cold water", which can adapt to the temperature rise-cooling cycle working condition of semiconductor equipment and ensure long-term service stability.

[0030] (5) High process controllability, suitable for high precision requirements of semiconductor: the parameters at each link (such as ultrasonic cleaning frequency, spraying flow, sintering rate) are quantified, and the hierarchical gradient spraying precisely controls the thickness (20-30 μm) and uniformity of the coating, ensuring the consistency of the performance of the coating in batch production and meeting the stringent requirements of semiconductor equipment on coating precision. DETAILED DESCRIPTION

[0031] Now a variety of exemplary embodiments of the present application will be described in detail, which should not be considered as limiting the present application, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present application. It should be understood that the terms described in the present application are only for the description of the particular embodiments, and are not used to limit the present application.

[0032] In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value within the range and any other stated value or intermediate value within the range is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.

[0033] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application pertains. Although preferred methods and materials are described, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are concerned. In the event of any conflict between the content of this specification and any document incorporated by reference, the content of this specification will control.

[0034] Many modifications and variations of the described implementations of the application can be made without departing from its spirit or scope, as will be apparent to those skilled in the art. Other implementations of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only.

[0035] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended and do not exclude additional elements or steps.

[0036] The present application provides a high-temperature-resistant nano-composite ceramic coating, comprising the following components by mass fraction:

[0037] 15-18 parts of nano , 25-30 parts of nano , 10-12 parts of modified nano , 3-5 parts of nano , 35-40 parts of acidic silicon solution, 2-3 parts of nano , and 1-2 parts of nano SiC.

[0038] Preferably, the components by mass fraction are preferably: 15-16 parts of nano , 25-28 parts of nano , 10-11 parts of modified nano , 3-4 parts of nano , 35-36 parts of acidic silicon solution, 2 parts of nano , and 2 parts of nano SiC.

[0039] The present application does not make special limitations on the acidic silicon solution, and commercially available acidic silicon sol can be used, and only needs to meet the conditions that the solid content is 30-40%, the SiO2 particle size is 10-20 nm, and the pH value is 2-4.

[0040] In the present application, the modified nano is preferably obtained by the following method:

[0041] 2-5 wt.% of nano is added to a 1 mol / L sodium hydroxide solution, high-speed stirring is performed for 10-15 min, and then ultrasonic treatment is performed for 20-30 min to obtain a mixed solution;

[0042] Subsequently, the mixed solution is placed in a high-speed centrifuge, centrifuged at a speed of 5000 r / min for 10 min, washed with ethanol and centrifuged, and the operation is repeated 2-5 times to obtain activated nano ;

[0043] The activated nano Placed in a hydrochloric acid solution with a pH value of 4-5, mixed to obtain a second mixed solution;

[0044] The silane coupling agent is placed in the second mixed solution for reaction, and after stirring for 3-4 h, it is washed with ethanol, centrifuged 2-5 times, and finally dried in an atmosphere at a temperature of 105-120℃ for 2 h to obtain modified nano .

[0045] The modified nano SiO2 of the present application has the following effects:

[0046] The compatibility of nano SiO2 and the coating system is improved, and component separation is avoided: there are a large number of hydroxyl groups (-OH) on the surface of unmodified nano SiO2, which is easy to cause agglomeration due to intermolecular hydrogen bonds, and the interface bonding force between its hydrophilic surface and components such as acid silicon solution, nano , etc. in the coating is weak, which may lead to uneven dispersion of the coating slurry, ultimately causing the coating to crack and fall off. The present application uses the process of "sodium hydroxide activation + silane coupling agent modification" (firstly increasing the surface active site by alkali treatment, and then grafting organic functional groups with silane coupling agent), which can change the surface of nano SiO2 from "hydrophilic" to "amphoteric / hydrophobic", and can be more uniformly dispersed in the acid silicon solution matrix, reducing the agglomeration phenomenon and ensuring that the coating components form a stable overall structure, laying a foundation for subsequent high-temperature resistance and crack resistance.

[0047] The bonding strength of the coating and the graphite substrate is enhanced, and the interface failure is reduced: the surface of the graphite substrate is relatively smooth and has strong chemical inertness, so ordinary nano SiO2 is difficult to form a firm bond with the substrate, and is easy to peel off from the surface of the substrate due to the difference in thermal expansion coefficient. The modified nano SiO2: on the one hand, after alkali activation and pH adjustment with hydrochloric acid, more active groups (such as carboxyl and hydroxyl) are formed on the surface, which can chemically bond with the oxygen-containing functional groups (such as -COOH and -OH) produced after the graphite substrate is activated (soaked in 5% dilute nitric acid); on the other hand, the organic segment of the silane coupling agent can act as a "bridge", connecting one end of the nano SiO2 and the other end of the active site on the surface of the graphite substrate, significantly improving the interface bonding force between the coating and the substrate, and avoiding the peeling of the coating due to thermal stress under high-temperature working conditions (such as the heating process in semiconductor production).

[0048] The microstructure of the coating was optimized to improve its high-temperature resistance and thermal shock resistance: Semiconductor manufacturing equipment needs to withstand high-temperature environments for extended periods and may face temperature fluctuations (thermal shock). Single ceramic coatings are prone to cracking due to mismatched coefficients of thermal expansion. The addition of modified nano-SiO2 can act as a "micro-skeleton": its uniform particle size and good dispersion can fill the tiny pores inside the coating, reducing the increase in porosity caused by gas escape at high temperatures; at the same time, SiO2 itself has good high-temperature resistance, and its synergistic effect with nano-B2O3 and nano-ZrO2 can reduce the overall difference in the coefficient of thermal expansion of the coating, improve the structural stability of the coating at high temperatures, and reduce the risk of cracking caused by thermal shock.

[0049] To enhance the chemical corrosion resistance of the coating and adapt it to the semiconductor manufacturing environment: Semiconductor manufacturing processes may involve contact with corrosive media such as acids and alkalis, requiring the coating to possess a certain degree of chemical resistance to prevent corrosion. Modified nanomaterials... The functional groups (such as amino and epoxy groups) of the silane coupling agent on the surface can interact with other components in the coating (such as nano-coatings). (SiC) forms a cross-linked structure, constructing a denser "chemical barrier" to prevent corrosive media from penetrating into the coating or the substrate surface; simultaneously, It has high chemical stability and does not easily react with acids and alkalis, which can further enhance the coating's resistance to chemical corrosion and extend the service life of semiconductor devices.

[0050] This invention also provides a method for preparing the high-temperature resistant nanocomposite ceramic coating described above, comprising the following steps:

[0051] Substrate pretreatment: The substrate surface is cleaned, then ultrasonically cleaned and dried, and the substrate is surface activated to obtain the pretreated substrate;

[0052] Material preparation: Prepare ceramic coating raw material components, mix the ceramic coating raw material components in proportion, and prepare a coating slurry;

[0053] Coating preparation: In a constant temperature and humidity environment, the coating slurry is sprayed onto the surface of the substrate in a layered gradient spraying manner to obtain a substrate with a coating.

[0054] Post-coating treatment: After drying the coated substrate, sintering is performed to obtain a sintered high-temperature resistant nanocomposite ceramic coating based on graphite surface.

[0055] Strengthening treatment: The surface of the sintered graphite-based high-temperature resistant nanocomposite ceramic coating is strengthened by plasma surface treatment to obtain the graphite-based high-temperature resistant nanocomposite ceramic coating.

[0056] Pre-treatment of the substrate: clean the surface of the substrate, then ultrasonic cleaning and drying of the substrate, and the surface of the substrate is activated to obtain the pre-treatment of the substrate;

[0057] Before coating, the substrate is first pre-treated, the surface of the substrate is cleaned, the graphite substrate is easy to attach oil stains (such as lubricating oil in the processing process), dust impurities and oxide layer (graphite is easy to be slightly oxidized and form loose carbon oxide when exposed to air for a long time) during storage and processing. Through the steps of "mechanical polishing cleaning (remove oil stains, impurities and oxides) + ultrasonic cleaning (20-40 kHz frequency, 150-300 W power, clean for 15-30 min with anhydrous ethanol / deionized water)", all kinds of pollutants on the surface of the substrate can be completely removed: mechanical polishing can physically remove stubborn oxide layer and large particle impurities, and ultrasonic cleaning can strip small oil stains and residual impurities through high-frequency vibration, which can clear the obstacles for the combination of the subsequent coating and the substrate.

[0058] In addition, graphite itself has strong chemical inertness and few active sites on the surface. If the coating is directly sprayed, the coating components (such as modified nano acidic silicon solution) are difficult to form a firm bond with the substrate, and the coating is easy to crack and peel off under high temperature working conditions due to thermal stress (difference in thermal expansion coefficient between graphite and ceramic coating). The activation treatment of "5% dilute nitric acid soaking (60°C, 30 min) + 105°C vacuum drying + inert gas preservation" can improve the surface activity of the substrate in the following ways: introducing active functional groups: the strong oxidizing property of dilute nitric acid can etch micro-pits on the surface of graphite (increase the specific surface area) and generate oxygen-containing active groups (such as -COOH, -OH); enhancing the chemical bonding ability: these active groups can chemically bond with the active sites (such as carboxyl and silane coupling agent functional groups) on the surface of the modified nano coating, forming a strong bonding force at the "substrate-coating" interface; avoiding secondary pollution / oxidation: vacuum drying can prevent interface bubbles caused by water residue, and inert gas preservation can avoid re-oxidation of the activated substrate surface, ensuring the stable retention of active sites and providing a "highly active" substrate surface for subsequent coating preparation. The steps of "mechanical polishing (ensure surface flatness) + ultrasonic cleaning (uniformly remove impurities) + 105-120°C drying for 2h (completely remove water)" in the pre-treatment of the substrate can make the surface of the graphite substrate reach the state of "flat, clean, dry and active uniformity", ensuring that the coating slurry can be uniformly attached during the subsequent layered gradient spraying (5-10 μm for the bottom layer, 10-15 μm for the middle layer, and 5 μm for the surface layer), and forming a coating with consistent thickness and stable performance after sintering, which meets the high precision requirements of semiconductor production equipment for the coating.

[0059] In the application, the substrate is preferably a graphite material, the surface of the substrate is preferably cleaned by mechanical polishing, specifically including removing oil stains, impurities and oxides on the surface; the parameters of the ultrasonic cleaning are preferably: frequency 20-40 kHz, power 150-300 W, cleaning time 15-30 minutes, and the cleaning medium of the ultrasonic cleaning is anhydrous ethanol or deionized water; the parameters of the drying are preferably: temperature 105-120 DEG C, and time 2 h.

[0060] In the application, the activation treatment is specifically preferably: immersing the dried substrate into a 5% dilute nitric acid solution with a temperature of 60 DEG C for 30 min, then taking out and cleaning, vacuum drying at a temperature of 105 DEG C for 1 h, and finally transferring into a sealed container protected by inert gas for storage.

[0061] Material preparation: preparing ceramic coating raw material components, mixing the ceramic coating raw material components according to proportions to prepare coating slurry;

[0062] The application does not specially limit the mixing mode of the ceramic coating raw material components, and a single mixing mode can be adopted, or a multi-stage mixing mode can be adopted according to needs.

[0063] Coating preparation: in a constant temperature and humidity environment, the coating slurry is sprayed on the surface of the substrate by a layered gradient spraying mode to obtain a substrate with a coating;

[0064] In the application, a gradient structure of "transition layer-intermediate layer-surface layer" is constructed when the coating is prepared, the difference in thermal expansion coefficients is relieved, and the coating cracking is reduced. The difference in thermal expansion coefficients between the graphite substrate and the ceramic coating is large (the thermal expansion coefficient of graphite is about 4-6*10 -6 / ℃, and the thermal expansion coefficients of B4C, ZrO2 and other components in the ceramic coating are about 5-10*10 -6 / ℃), if a single thickness / flow rate spraying is adopted, the coating is prone to cracking and falling off due to thermal stress concentration under high temperature working conditions (such as the heating process in semiconductor production, and coating sintering at 800-1050 DEG C). The layered gradient spraying can realize the smooth transition of "graphite substrate-coating" by "forming a 5-10 mu m transition layer with a low flow rate (10 mL / min, 50 cm distance) in the bottom layer": the transition layer is thin in thickness and small in spraying pressure, can form a close combination with the activated graphite substrate (treated by 5% dilute nitric acid), and at the same time, the components can fully react with the active groups on the surface of the substrate through slow penetration, so as to reduce the thermal stress at the interface; the intermediate layer (15 mL / min, 40 cm distance, 10-15 mu m) acts as a "buffer layer", which can further balance the thermal expansion difference between the substrate and the surface layer; the surface layer (20 mL / min, 30 cm distance, 5 mu m) focuses on performance enhancement, and the three layers synergistically avoid the cracking risk of a single coating caused by the mismatch of thermal expansion from the structure.

[0065] The layered gradient spraying method can also optimize the coating micro-densification, reduce porosity and defects, and improve high-temperature resistance and corrosion resistance. Semiconductor production equipment needs to withstand high temperature (long-term above 800°C) and chemical corrosion (such as acid and alkali medium), and if the coating has porosity, it will cause high-temperature gas penetration and corrosive medium intrusion, eventually leading to coating failure or substrate damage. Layered gradient spraying can precisely control the coating densification through the combination of "flow + distance + infrared pre-baking": low flow + long distance in the bottom layer: the slurry is atomized more finely during spraying, the particles are deposited uniformly, and the transition layer formed can fill the small pits on the surface of the graphite substrate, reducing the porosity of the substrate-coating interface; medium flow + medium distance in the middle layer: 2-3 layers are added on the basis of the transition layer, and the spraying amount is gradually increased to further fill the possible small pores in the bottom layer and build a continuous "barrier layer"; high flow + short distance in the surface layer: the spraying pressure is larger, and the slurry particles are more tightly packed on the substrate surface. At the same time, 80°C, 3min infrared pre-baking after each layer of spraying can remove the solvent in the slurry (such as water in the acidic silicon solution) in time, avoiding the generation of bubble porosity due to solvent vaporization during high-temperature sintering.

[0066] The finally formed coating has gradually optimized densification from inside to outside, which can effectively block the penetration of high-temperature gas and corrosive medium, and adapt to the harsh environment of semiconductor production.

[0067] The performance of "bonding strength-strength-protection" is layered and adapted to meet multi-dimensional requirements. The core requirement of semiconductor production for ceramic coating is "strong bonding (not falling off), high temperature resistance (anti-high temperature deformation), and excellent protection (anti-corrosion)", and a single coating cannot meet the multi-dimensional performance requirements. Layered gradient spraying can achieve targeted performance optimization through layered design: bottom layer (transition layer): focus on "strong bonding force", low flow spraying ensures that the coating is in full contact with the substrate, and the active sites of the activated substrate are used to maximize the interfacial bonding force, solving the core problem of "coating falling off"; middle layer (buffer layer): focus on "structural strength and high temperature resistance", increase the overall thickness of the coating by 2-3 layers, and use the synergistic effect of nano-B2O3 (forming a glass phase to fill the gaps) and nano-Al2O3 (improving strength) to provide the coating with "structural support" for high temperature resistance and deformation resistance; surface layer: focus on "protection performance", the dense surface layer formed by high-flow spraying can directly resist external chemical corrosion and high-temperature erosion, and the concentrated effect of nano-SiC (wear-resistant) and nano-ZrO2 (anti-thermal shock) further strengthens the protection ability of the surface layer, achieving "bottom layer for bonding, middle layer for strength, and surface layer for protection".

[0068] Layered gradient spraying also improves process stability through "layered quantitative control":

[0069] Parameter precision: the flow rate (10 / 15 / 20 mL / min), distance (50 / 40 / 30 cm), layer number (1-2 / 2-3 / 1 layer), and thickness (5-10 / 10-15 / 5 µm) of the bottom layer / intermediate layer / surface layer are quantified, which can be precisely adjusted according to the requirements to avoid human operation errors;

[0070] Infrared pre-baking assistance: 80℃ pre-baking after spraying each layer can quickly fix the coating morphology, prevent the bottom layer slurry from being washed and deformed during subsequent spraying, and ensure the controllable thickness of each layer;

[0071] Finally, the overall thickness (20-30 µm) of the coating is uniform, and the performance of each layer is stable, which meets the requirements of high precision and high consistency of the coating for semiconductor equipment.

[0072] In the present application, the gradient spraying is specifically preferred as follows: 1-2 layers of the bottom layer are sprayed by low flow rate to form a transition layer with a thickness of 5-10 µm; 2-3 layers of the intermediate layer are sprayed by medium flow rate with a thickness of 10-15 µm; and 1 layer of the surface layer is sprayed by high flow rate with a thickness of 5 µm; and infrared pre-baking is performed after spraying each layer, the temperature of the infrared pre-baking is 80℃, and the time is 3 min.

[0073] In the present application, the nozzle flow rate of the low flow rate spraying is 10 mL / min, and the distance is 50 cm; the nozzle flow rate of the medium flow rate spraying is 15 mL / min, and the distance is 40 cm; and the nozzle flow rate of the high flow rate spraying is 20 mL / min, and the distance is 30 cm.

[0074] Coating post-processing: after the substrate with the coating is subjected to drying treatment, sintering treatment is performed to obtain the sintered graphite surface high-temperature-resistant nano-composite ceramic coating.

[0075] In the present application, the drying treatment in the coating post-processing is specifically preferred as follows: the substrate with the coating is placed in a 105-120℃ oven for drying for 2 h; and the sintering treatment is preferably as follows: the substrate with the coating is placed in a heating furnace, the temperature is increased to 800-1050℃ at a heating rate of 5℃ / min, and the temperature is maintained for 2-3 h, and finally the furnace is cooled to room temperature.

[0076] Strengthening treatment: the sintered graphite surface high-temperature-resistant nano-composite ceramic coating is subjected to strengthening treatment by plasma surface treatment to obtain the graphite surface high-temperature-resistant nano-composite ceramic coating.

[0077] The coating surface is finally subjected to strengthening treatment, and the strengthening treatment has the following effects:

[0078] The dense coating surface layer blocks the penetration of corrosive media and high-temperature gas: after sintering at 800-1050°C, the coating has formed a whole structure, but there may be small pores in the surface layer (due to solvent volatilization and slight shrinkage of components during sintering), which can become the penetration channel of "acid and alkaline corrosive media" (such as chemical reagents in the semiconductor cleaning process) and "high-temperature gas" (such as gas generated by equipment heating) in semiconductor production, leading to internal degradation of the coating or corrosion of the substrate.

[0079] Plasma surface treatment achieves surface densification by the following means: argon plasma at a power of 500W and a low pressure of 10Pa can form a high-energy ion stream (such as Ar + ), which can fill the small pores in the surface layer with "molten / plastic" ceramic components (such as SiO2, B2O3 glass phase) when bombarding the surface layer; at the same time, high-energy ions can promote the secondary diffusion and bonding of surface layer particles, reduce porosity, and finally form a "dense barrier" on the surface of the coating, completely blocking the penetration path of external harmful media, and strengthening the chemical corrosion resistance and high-temperature sealing performance of the coating.

[0080] Improve the surface hardness and wear resistance of the coating to resist mechanical damage in semiconductor production:

[0081] During assembly, maintenance or operation of semiconductor production equipment (such as rack modules), the coating surface may face slight friction (such as component docking, dust scouring), and if the surface hardness of the coating is insufficient, scratches and wear may occur, damaging the integrity of the coating.

[0082] The "high-energy effect" of plasma bombardment can significantly improve the surface hardness of the coating: on the one hand, high-energy ions can cause "lattice distortion" in the crystal structure of the coating surface layer, forming a more compact crystal arrangement (such as nano-SiC, surface crystallinity of the particles is improved); on the other hand, the energy of the plasma can promote the reconfiguration of chemical bonds in the surface layer components (such as the formation of more stable composite phases of SiO2 and ZrO2), enhancing the bonding force between the surface layer particles. Ultimately, the surface hardness of the coating is improved, the wear resistance is enhanced, and it can resist slight mechanical damage in semiconductor production, prolonging the service life of the coating.

[0083] Repairing the surface micro-cracks of the coating after sintering to avoid defect expansion leading to coating failure:

[0084] During the sintering and cooling process of the coating, due to the slight difference in the thermal expansion coefficients of the components, the surface layer may produce "micro-cracks" that are not visible to the naked eye (especially when the surface layer thickness is only 5μm and the structure is relatively fragile). If these micro-cracks are not treated, they will gradually expand into macro-cracks under long-term high-temperature cyclic (thermal shock) conditions of semiconductor equipment, eventually leading to coating cracking and peeling.

[0085] The plasma surface treatment can realize micro crack repair: when the high-energy argon plasma bombards the coating surface layer, heat and energy are transmitted to the surface layer, so that the local temperature of the surface layer is increased to a'semi-melting state' (without reaching the overall sintering temperature to avoid damage to the coating structure), at this time, the ceramic components (such as low-melting-point ) in the surface layer will have a certain fluidity and can fill into the micro crack gap; at the same time, the plasma energy can promote the recombination of particles at the crack edge, realize the 'healing' of the micro crack, prevent the defect from expanding from the source, ensure that the coating maintains the structural integrity in the high-temperature thermal shock environment (such as the temperature rise-cooling cycle of the semiconductor equipment), and avoid coating failure.

[0086] In the present application, the plasma surface treatment is specifically: the coating surface is subjected to plasma bombardment for 3min in an argon atmosphere, the power of the plasma bombardment is 500W, and the gas pressure is 10Pa.

[0087] The present application also provides application of the high-temperature-resistant nano-composite ceramic coating in semiconductor production, and the high-temperature-resistant nano-composite ceramic coating based on the graphite surface is the nano-composite ceramic coating in the above technical solution.

[0088] Example 1

[0089] I. Coating components

[0090] 15 parts of nano , 25 parts of nano , 10 parts of modified nano , 3 parts of nano , 35 parts of acidic silicon solution, 2 parts of nano , 1 part of nano SiC.

[0091] II. Preparation of modified nano

[0092] 2wt.% of nano is added to 1mol / L sodium hydroxide solution, high-speed stirring is carried out for 10min, and then ultrasonic treatment is carried out for 20min to obtain a mixed solution;

[0093] The mixed solution is placed in a high-speed centrifuge and centrifuged at a speed of 5000r / min for 10min, washed with ethanol and centrifuged, and the operation is repeated twice to obtain activated nano ;

[0094] The activated nano is placed in a hydrochloric acid solution with a pH value of 4, and a second mixed solution is obtained by mixing;

[0095] ​The second mixed solution was added with a silane coupling agent, washed with ethanol, centrifuged twice, and finally dried in an atmosphere at 105°C for 2h to obtain modified nano .

[0096] III. Coating preparation method

[0097] Substrate pretreatment: graphite was selected as the substrate, and mechanical polishing was used to remove surface oil stains, impurities and oxides; then ultrasonic cleaning was performed with a frequency of 20 kHz, a power of 150 W, a cleaning time of 15 minutes, and anhydrous ethanol as the cleaning medium; after cleaning, the substrate was dried at 105°C for 2h; the dried substrate was immersed in a 5% dilute nitric acid solution at 60°C for 30min, taken out, cleaned and vacuum dried at 105°C for 1h, and then stored in a sealed container under inert gas protection to obtain the pretreated substrate.

[0098] Material preparation: the raw materials were mixed according to the above coating component ratio to prepare the coating slurry.

[0099] Coating preparation: in a constant temperature and humidity environment, layered gradient spraying was adopted: low flow (nozzle flow 10mL / min, distance 50cm) was used to spray 1 layer of bottom layer to form a transition layer with a thickness of 5μm; medium flow (nozzle flow 15mL / min, distance 40cm) was used to spray 2 layers of middle layer with a thickness controlled at 10μm; high flow (nozzle flow 20mL / min, distance 30cm) was used to spray 1 layer of surface layer with a thickness of 5μm; after each layer was sprayed, infrared pre-drying was performed at 80°C for 3min to obtain the substrate with coating.

[0100] Coating post-treatment: the substrate with coating was placed in a 105°C oven and dried for 2h; then it was placed in a heating furnace and heated to 800°C at a rate of 5°C / min, and held for 2h, and then cooled to room temperature with the furnace to obtain the sintered coating.

[0101] Strengthening treatment: the surface of the sintered coating was subjected to 3min plasma bombardment in an argon atmosphere with a power of 500W and a gas pressure of 10Pa to obtain the high-temperature-resistant nano-composite ceramic coating.

[0102] Example 2

[0103] I. Coating components

[0104] 16.5 parts of nano , 27.5 parts of nano , 11 parts of modified nano , 4 parts of nano , 37.5 parts of acidic silicon solution, 2.5 parts of nano , 1.5 parts of nano SiC.

[0105] II. Modified nano Preparation

[0106] To 1 mol / L sodium hydroxide solution, 3.5 wt.% of nano was added, and high-speed stirring was carried out for 12 min, followed by ultrasonic treatment for 25 min, to obtain a mixed solution;

[0107] The mixed solution was placed in a high-speed centrifuge and centrifuged at a speed of 5000 r / min for 10 min, washed with ethanol and centrifuged, and the operation was repeated 3 times, to obtain activated nano ;

[0108] The activated nano was placed in a hydrochloric acid solution with a pH value of 4.5, and mixing was carried out to obtain a second mixed solution;

[0109] To the second mixed solution, a silane coupling agent was added, and after stirring for 3.5 h, the mixture was washed with ethanol and centrifuged 3 times, and finally dried in an atmosphere at 110°C for 2 h, to obtain modified nano .

[0110] III. Coating preparation method

[0111] Substrate pretreatment: graphite was selected as the substrate, and mechanical polishing was used to remove surface oil stains, impurities and oxides; the ultrasonic cleaning parameters were a frequency of 30 kHz, a power of 225 W and a cleaning time of 22 min, and deionized water was used as the cleaning medium; after cleaning, the substrate was dried at 110°C for 2 h; the dried substrate was immersed in a 5% dilute nitric acid solution at 60°C for 30 min, taken out, cleaned and dried in a vacuum oven at 105°C for 1 h, and then transferred into a sealed container under inert gas protection for storage, to obtain a pretreated substrate.

[0112] Material preparation: the raw materials were mixed according to the above coating component proportions, and a coating slurry was prepared.

[0113] Coating preparation: in a constant temperature and humidity environment, the substrate was sprayed in layers and gradients: 1.5 layers of the bottom layer were sprayed at a low flow rate (nozzle flow rate 10 mL / min, distance 50 cm), to form a transition layer with a thickness of 7.5 μm; 2.5 layers of the middle layer were sprayed at a medium flow rate (nozzle flow rate 15 mL / min, distance 40 cm), and the thickness was controlled at 12.5 μm; 1 layer of the surface layer was sprayed at a high flow rate (nozzle flow rate 20 mL / min, distance 30 cm), and the thickness was 5 μm; after each layer was sprayed, the substrate was pre-baked at 80°C for 3 min, to obtain a substrate with a coating.

[0114] Coating post-treatment: the substrate with the coating was placed in a 110°C oven and dried for 2 h; it was placed in a heating furnace, and the temperature was increased to 925°C at a heating rate of 5°C / min, and held for 2.5 h, and then the furnace was cooled to room temperature, to obtain a sintered coating.

[0115] Strengthening treatment: the surface of the sintered coating is subjected to plasma bombardment for 3 min in an argon atmosphere at a power of 500 W and a gas pressure of 10 Pa, to obtain a high-temperature-resistant nano-composite ceramic coating.

[0116] Example 3

[0117] I. Coating components

[0118] 18 parts of nano , 30 parts of nano , 12 parts of modified nano , 5 parts of nano , 40 parts of acidic silicon solution, 3 parts of nano , 2 parts of nano SiC.

[0119] II. Modified nano Preparation

[0120] 5wt.% of nano was added to a 1 mol / L sodium hydroxide solution, high-speed stirring was performed for 15 min, followed by ultrasonic treatment for 30 min, to obtain a mixed solution;

[0121] The mixed solution was placed in a high-speed centrifuge and centrifuged at a speed of 5000 r / min for 10 min, washed with ethanol and centrifuged, and the operation was repeated 5 times, to obtain activated nano .

[0122] The activated nano was placed in a hydrochloric acid solution with a pH value of 5, and a second mixed solution was obtained by mixing;

[0123] Silane coupling agent was added to the second mixed solution, and after stirring for 4 h, the mixture was washed with ethanol and centrifuged 5 times, and finally dried in an atmosphere at 120℃ for 2 h, to obtain modified nano .

[0124] III. Coating preparation method

[0125] Substrate pretreatment: graphite was selected as the substrate, and the surface was mechanically polished to remove oil stains, impurities and oxides; the ultrasonic cleaning parameters were a frequency of 40 kHz, a power of 300 W, and a cleaning time of 30 minutes, and the cleaning medium was anhydrous ethanol; after cleaning, the substrate was dried at 120℃ for 2 h; the dried substrate was immersed in a 5% dilute nitric acid solution at 60℃ for 30 min, taken out, cleaned and dried in a vacuum oven at 105℃ for 1 h, and then transferred to a sealed container under inert gas protection to obtain a pretreated substrate.

[0126] Material preparation: the raw materials were mixed according to the above coating component proportions to prepare a coating slurry.

[0127] Coating preparation: In a constant temperature and humidity environment, layered gradient spraying: low flow (nozzle flow 10 mL / min, distance 50 cm) spraying 2 layers of bottom layer to form a transition layer with a thickness of 10 μm; medium flow (nozzle flow 15 mL / min, distance 40 cm) spraying 3 layers of middle layer, thickness controlled at 15 μm; high flow (nozzle flow 20 mL / min, distance 30 cm) spraying 1 layer of surface layer, thickness 5 μm; after spraying each layer, infrared pre-drying at 80℃ for 3 min, to obtain the coated substrate.

[0128] Coating post-processing: put the coated substrate into a 120℃ oven and dry for 2h; put it into a heating furnace, increase the temperature to 1050℃ at a rate of 5℃ / min, keep it for 3h, and cool it to room temperature with the furnace, to obtain the sintered coating.

[0129] Strengthening treatment: plasma bombardment on the surface of the sintered coating in an argon atmosphere with a power of 500W and a gas pressure of 10Pa for 3min, to obtain a high-temperature-resistant nano-composite ceramic coating.

[0130] Test Example 1: High-temperature resistance test

[0131] 1. Test sample

[0132] The "graphite substrate + composite ceramic coating" samples prepared in Example 1, Example 2 and Example 3 are each 50mm x 50mm x 5mm in size, and 3 parallel samples are prepared for each group.

[0133] 2. Test equipment and parameters

[0134] Equipment: box-type resistance furnace (temperature control accuracy ±5℃), electronic analytical balance (accuracy 0.1mg), optical microscope (magnification 200x)

[0135] Test conditions: put the sample into the resistance furnace, increase the temperature to 1000℃ (higher than the upper limit of the sintering temperature, simulate extreme high temperature) at a rate of 5℃ / min, keep it for 48h, and cool it to room temperature with the furnace.

[0136] Test results are shown in Table 1

[0137] Table 1: High-temperature resistance test results

[0138]

[0139] Based on Table 1, the weight loss rate, appearance and thickness change of the coatings of the three groups of examples after 48h of high-temperature resistance at 1000℃ all meet the performance target, the weight loss rate is small, the appearance change is slight, and the high-temperature resistance performance is excellent, which can adapt to the high-temperature working conditions in semiconductor production.

[0140] Test Example 2: Chemical corrosion resistance test

[0141] 1. Test samples

[0142] Same as Test Example 1, each group of samples has 3 parallel samples, and the coating surface is cleaned with anhydrous ethanol before testing and dried.

[0143] 2. Test equipment and parameters

[0144] Equipment: constant temperature soaking tank (temperature control accuracy ±1℃), electronic analytical balance, scanning electron microscope (SEM)

[0145] Test medium and conditions: ①10wt.% hydrochloric acid solution (25℃, soaking for 24h); ②5wt.% sodium hydroxide solution (25℃, soaking for 24h); ③ cleaning solution commonly used in semiconductor production (ammonia-hydrogen peroxide mixture, volume ratio 1:1:5, 25℃, soaking for 24h).

[0146] The test results are shown in Table 2

[0147] Table 2 Test results of chemical corrosion resistance

[0148]

[0149] Based on Table 2, the weight loss rate of the coatings of the three groups of examples is low and there is no obvious corrosion defect on the surface after soaking in the three typical corrosion media for 24h, and the chemical corrosion resistance meets the protection requirements of the coating for semiconductor production.

[0150] Test Example 3 Bonding strength and thermal shock resistance test

[0151] 1. Test samples

[0152] Bonding strength test samples: Example 1-3 coating samples (size 50mm×50mm×5mm);

[0153] Thermal shock resistance test samples: same as Test Example 1, each group has 3 parallel samples.

[0154] 2. Test equipment and parameters

[0155] (1) Bonding strength test

[0156] Crosshatch method: a crosshatch knife (spacing 1mm) is used to draw a 10×10 grid on the surface of the coating, and then 3M tape is pasted and quickly torn off, and the coating peeling is observed;

[0157] Pull-off method: according to GB / T 5210-2006 "Color paint and varnish pull-off method adhesion test", a pull-off adhesion tester is used to test the interfacial pull-off strength of the coating and the graphite substrate.

[0158] (2) Thermal shock resistance test

[0159] Equipment: Box resistance furnace, cold water tank (25℃)

[0160] Cycling condition: Put the sample into the furnace, increase the temperature to 800℃ at 5℃ / min, keep for 30min, take out quickly and put into 25℃ cold water for 5min, complete one cycle, complete 50 cycles in total, observe the appearance change of the coating.

[0161] The test results are shown in Table 3

[0162] Table 3 Test results of bonding strength and thermal shock resistance

[0163]

[0164] Based on Table 3, the coating bonding strength (crosshatch 0 level, pull-off strength ≥8.5MPa) and thermal shock resistance (50 cycles without defects) of the three groups of examples all meet the performance target, which can effectively resist the external force and thermal shock in the operation of semiconductor equipment and ensure the long-term stable adhesion of the coating.

[0165] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application but not to limit it, although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that: the specific embodiments of the present application can still be modified or replaced by the equivalent, without departing from the spirit and scope of the present application, any modification or equivalent replacement, which should be covered in the protection scope of the claims of the present application.

Claims

1. A method for preparing a high-temperature resistant nanocomposite ceramic coating, characterized in that, The method comprises the following steps: Substrate pretreatment: clean the surface of the substrate, then ultrasonically clean and dry the substrate, and perform surface activation treatment on the substrate to obtain a pretreated substrate; Material preparation: prepare ceramic coating raw material components, mix the ceramic coating raw material components according to proportions to prepare a coating slurry, and the coating slurry comprises the following components in mass fractions: 15-18 parts of nano B4C, 25-30 parts of nano B2O3, 10-12 parts of modified nano SiO2, 3-5 parts of nano Al2O3, 35-40 parts of acidic silica sol, 2-3 parts of nano ZrO2 and 1-2 parts of nano SiC; Coating preparation: in a constant-temperature and constant-humidity environment, the coating slurry is sprayed on the surface of the substrate in a layered gradient spraying manner to obtain a substrate with a coating; Coating post-treatment: after drying treatment, the substrate with the coating is subjected to sintering treatment to obtain a sintered graphite surface-based high-temperature-resistant nano composite ceramic coating; Strengthening treatment: the surface of the sintered graphite surface-based high-temperature-resistant nano composite ceramic coating is subjected to strengthening treatment in a plasma surface treatment manner to obtain the graphite surface-based high-temperature-resistant nano composite ceramic coating. The modified nano SiO2 is obtained by sodium hydroxide activation and silane coupling agent modification.

2. The method of claim 1, wherein the high-temperature resistant nanocomposite ceramic coating is prepared by a process comprising: The modified nano SiO2 is obtained by the following method: 2-5 wt.% of nano SiO2 is added to 1 mol / L sodium hydroxide solution, high-speed stirring is performed for 10-15 min, and then ultrasonic treatment is performed for 20-30 min to obtain a mixed solution; Then the mixed solution is placed in a high-speed centrifuge, centrifuged at a speed of 5000 r / min for 10 min, washed and centrifuged with ethanol, and repeated 2-5 times to obtain activated nano SiO2; The activated nano SiO2 is placed in a hydrochloric acid solution with a pH value of 4-5, and a second mixed solution is obtained after mixing; The silane coupling agent is placed in the second mixed solution for reaction, stirred for 3-4 h, washed with ethanol and centrifuged 2-5 times, and finally dried in an atmosphere at a temperature of 105-120℃ for 2 h to obtain modified nano SiO2.

3. The method of claim 1, wherein the high-temperature resistant nanocomposite ceramic coating is prepared by a process comprising: The substrate is a graphite material, the surface of the substrate is cleaned by mechanical polishing, which specifically includes removing oil stains, impurities and oxides on the surface; the parameters of the ultrasonic cleaning are as follows: frequency 20-40 kHz, power 150-300 W, cleaning time 15-30 min, and the cleaning medium of the ultrasonic cleaning is anhydrous ethanol or deionized water; the drying parameters are as follows: temperature 105-120℃, time 2 h.

4. The method of claim 1, wherein the high-temperature resistant nanocomposite ceramic coating is prepared by a process comprising: The surface activation treatment is specifically as follows: the dried substrate is immersed in a 5% dilute nitric acid solution at a temperature of 60℃ for 30 min, then taken out for cleaning, vacuum dried at a temperature of 105℃ for 1 h, and finally transferred into a sealed container protected by inert gas for storage.

5. The method for preparing a high-temperature resistant nanocomposite ceramic coating according to claim 1, characterized in that, The layered gradient spraying is specifically: spraying 1-2 layers of bottom layer by low flow spraying to form a transition layer with a thickness of 5-10 μm; spraying 2-3 layers of middle layer by medium flow spraying, with a thickness controlled in 10-15 μm, spraying 1 layer of surface layer by high flow spraying, with a thickness of 5 μm, and infrared pre-drying after spraying each layer, wherein the temperature of the infrared pre-drying is 80 ℃, and the time is 3 min.

6. The method of claim 5, wherein the method further comprises the step of: The nozzle flow of the low flow spraying is 10 mL / min, and the distance is 50 cm; the nozzle flow of the medium flow spraying is 15 mL / min, and the distance is 40 cm; and the nozzle flow of the high flow spraying is 20 mL / min, and the distance is 30 cm.

7. The method of claim 1, wherein the method further comprises the step of: The drying treatment in the coating post-treatment is specifically: placing the substrate with coating into a 105-120 ℃ oven for drying, with a time of 2 h; and the sintering treatment is: placing the substrate with coating into a heating furnace, increasing the temperature to 800-1050 ℃ at a heating rate of 5 ℃ / min, keeping the temperature for 2-3 h, and finally cooling to room temperature with the furnace. ​ 8. The method of claim 1, wherein the nanocomposite ceramic coating is a high-temperature resistant nanocomposite ceramic coating. The plasma surface treatment is specifically: performing 3 min plasma bombardment on the coating surface in an argon atmosphere, wherein the power of the plasma bombardment is 500 W, and the gas pressure is 10 Pa.

9. Use of a high-temperature resistant nanocomposite ceramic coating in semiconductor production, characterized by The high-temperature-resistant nano-composite ceramic coating is the nano-composite ceramic coating according to claim 1. The high-temperature-resistant nano-composite ceramic coating is the nano-composite ceramic coating according to claim 1.

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