Fluorosilicone-nano ceramic hybrid coating and preparation method thereof

Abstract

The invention provides a fluorine silicon-nano ceramic hybrid coating, which is characterized in that the fluorine silicon-nano ceramic hybrid coating is arranged on a substrate; in an area x [mu] m away from the substrate, the mass ratio of the fluorosilicone resin is y1%, and the mass ratio of the nano ceramic is y2%; y1 = a-kx, y2 = kx + b, 70 < = a < = 90, and 10 < = b < = 30. The invention discloses a preparation process of the coating, the coating is prepared from fluorosilicone resin and nano ceramic, and curing conditions in the process preparation process are regulated and controlled, so that the coating can stably work in a wide temperature range of-70 DEG C to 250 DEG C, the preparation cost of the coating can be effectively reduced, the pollution resistance of the coating can be improved, and the service life of the coating can be prolonged. And the high-cleanliness requirement of semiconductor manufacturing is met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ceramic materials, and particularly relates to a fluorosilicon-nanoceramic hybrid coating and a preparation method thereof. BACKGROUND

[0002] In a semiconductor manufacturing process, wafers and photomasks are core production materials, and their purity, surface integrity and pollution-free transmission are key factors to ensure product yield and process stability. Wafer boxes (such as FOUP) and photomask boxes (such as EUV photomask boxes) are key carriers for protecting wafers and photomasks from pollution, mechanical damage and environmental interference. Wafer boxes and photomask boxes are mainly made of plastic materials. However, during the storage and transmission of wafers and photomasks, wear particles and accumulated static electricity are generated due to frequent friction, and metal ion pollution (Na + ) is released during temperature changes and cleaning processes, resulting in wafer surface defects and affecting product yield and process accuracy. The current solution is to coat a protective coating on the inner surface of the semiconductor carrier to improve the anti-pollution and stability of the carrier.

[0003] The commonly used coating is fluorocarbon coating (PFA / PTFE), which can significantly reduce the risk of wafer surface particle pollution, but it is easily decomposed in high temperature (> 150℃) environment, and is brittle in low temperature environment (<-30℃), and the multi-layer structure process is complex and the cost is high. Therefore, a coating technology with high cleanliness, wide temperature range adaptability and low process cost needs to be developed. SUMMARY

[0004] The application provides a fluorosilicon-nanoceramic hybrid coating and a preparation method thereof. By using fluorosilicon resin and nanoceramics, the coating prepared by compounding and hybridizing the fluorosilicon resin and the nanoceramics on a substrate has high cleanliness, wide temperature range adaptability and low process cost.

[0005] In a first aspect, the present application provides a fluorosilicon-nanoceramic hybrid coating, comprising a fluorosilicon resin and a nanoceramic; the fluorosilicon-nanoceramic hybrid coating is arranged on a substrate; in a region x microns away from the substrate in the fluorosilicon-nanoceramic hybrid coating, the mass percentage of the fluorosilicon resin is y1%, and the mass percentage of the nanoceramic is y2%; y1=a-kx, y2=kx+b, 70≤a≤90, 10≤b≤30. The present application arranges the fluorosilicon resin and the nanoceramic on the substrate after hybridization. The fluorosilicon resin spontaneously moves towards the substrate due to its low surface energy, while the nanoceramic remains inside due to its high surface energy and moves away from the substrate. As the hybridization process proceeds, the nanoceramic and the fluorosilicon resin interpenetrate and crosslink to form a network structure. The content of fluorosilicon resin near the substrate is high, and the content of nanoceramic on the surface away from the substrate is high. This forms a transition from high nanoceramic content on the surface to high fluorosilicon resin content on the substrate. The coating can withstand high temperatures without deformation due to the high content of nanoceramic on the surface, and the high content of fluorosilicon resin on the substrate has elasticity, which can reduce the stress caused by thermal expansion and contraction during extreme temperature changes, thereby avoiding cracking of the coating. During the storage and transportation of wafers and photomasks, the high hardness of the nanoceramic and the low surface energy of the fluorosilicon resin work together to make the coating surface smooth and hydrophobic, reducing wear particles and particle adhesion caused by frequent friction during transportation. The nanoceramic, which is an insulator and inert material, can prevent static adsorption of particles while not being eroded by organic solvents during cleaning processes, thereby achieving high cleanliness of the coating. In addition, the fluorosilicon resin and the nanoceramic spontaneously form a functional layer due to the difference in surface energy, which can reduce the number of coating steps, reduce equipment investment and process cost. Therefore, the coating made of fluorosilicon resin and nanoceramic has high cleanliness, wide temperature range adaptability, and low process cost.

[0006] In some embodiments, when the fluorosilicon-nanoceramic hybrid coating only includes the fluorosilicon resin and the nanoceramic without other components, the sum of the mass percentages of the fluorosilicon resin and the nanoceramic is 100%, that is, a+b=100.

[0007] In some embodiments, 75≤a≤85, 15≤b≤25. When this condition is met, the fluorosilicon-nanoceramic hybrid coating prepared has high cleanliness, wide temperature range adaptability, and low process cost.

[0008] In some embodiments, 40≤y1≤90; 10≤y2≤60. When this condition is met, the fluorosilicon-nanoceramic hybrid coating prepared has high cleanliness, wide temperature range adaptability, and low process cost.

[0009] In some embodiments, the fluorosilicon-nanoceramic hybrid coating has a thickness of h μm, 50≤h≤80, and 0≤x≤h. When this condition is satisfied, the coating prepared has high cleanliness, wide temperature range adaptability, and low process cost.

[0010] In some embodiments, the fluorosilicon resin is copolymerized from methyl trifluoropropyl siloxane and tetramethyl tetravinylcyclotetrasiloxane; the molar ratio of methyl trifluoropropyl siloxane to tetramethyl tetravinylcyclotetrasiloxane is 70-95:5-30. When this condition is satisfied, the alkoxy and fluorine are covalently bonded to form a composite structure, the excellent heat and cold resistance of the organosilicon resin is maintained, and the solvent resistance, aging resistance, and extremely low surface energy of the fluorine compound are also possessed, so that the coating prepared has high cleanliness, wide temperature range adaptability, and low process cost.

[0011] In some embodiments, the nanoceramic includes zirconium oxide and silicon dioxide; the mass ratio of zirconium oxide to silicon dioxide is 70-80:20-30. When this condition is satisfied, the zirconium oxide and silicon dioxide in the nanoceramic form a composite structure with a synergistic effect, the excellent ion barrier property (Na + resistance), wear resistance, impact resistance, and resistance to extremely high temperature of zirconium oxide are maintained, and the high surface smoothness and electrical insulation of silicon dioxide are also possessed, so that the coating prepared has high cleanliness, wide temperature range adaptability, and low process cost.

[0012] In some embodiments, the nanoceramic has a particle size of 10-50 nm. When this condition is satisfied, the fluorosilicon-nanoceramic hybrid coating prepared has high cleanliness, wide temperature range adaptability, and low process cost.

[0013] In a second aspect, the application further provides a preparation method of a fluorosilicon-nanoceramic hybrid coating, including the following steps: Step S1: mixing fluorosilicon resin, nano-ceramics and ethanol solvent according to the mass ratio of 5:3:92 to obtain a mixture; adding 92% formic acid relative to the volume of the mixture to the mixture to catalyze hydrolysis, and ultrasonic dispersion to form a stable sol, the ultrasonic dispersion temperature is 25-30℃, the time is 30-40min, and the frequency is 40kHz; Step S2: spraying the stable sol on the surface of the substrate to form a wet film; the temperature of the substrate during spraying is 60-80℃, and the thickness of the wet film is 50-80μm; Step S3: performing a three-time heat treatment curing process on the wet film, including: the first time heat treatment curing temperature is 70-80℃, and the time is 120-150min; the second time heat treatment curing temperature is 140-160℃, and the time is 60-80min; the third time heat treatment curing temperature is 180-200℃, and the time is 20-40min. By gradually increasing the curing temperature and adjusting the curing time, the structure and performance of the fluorosilicon-nano-ceramic coating can be more accurately controlled. In the first curing, a lower temperature is used to induce cross-linking of the fluorosilicon resin, so that the nano-ceramic particles slowly settle in the fluorosilicon resin with high viscosity, and the particles can be uniformly dispersed. In the second curing, the temperature is increased to move the fluorine-containing segments in the fluorosilicon resin towards the substrate, while the nano-ceramic remains inside and moves away from the substrate, thereby promoting the formation of a nano-ceramic network. By slowly increasing the temperature, the stress generated by the rapid cross-linking of nano-ceramic and resin is reduced. In the third curing, the nano-ceramic is deeply cross-linked by high temperature to eliminate the stress generated in the previous two curing processes, prevent the coating from cracking, and realize the chemical bonding of fluorosilicon-ceramic, so that the prepared coating has high cleanliness, wide temperature range adaptability and low process cost.

[0014] In some embodiments, by adjusting the curing temperature of the second heat treatment, the settling rate of the fluorosilicon resin can be adjusted, and thus the distribution of the fluorosilicon resin and the nano-ceramic in the coating can be adjusted. For example, when the curing temperature of the second heat treatment is lowered, the settling rate of the fluorosilicon resin slows down, and the difference between the mass ratio of fluorosilicon resin in the bottom layer (close to the substrate) and the surface layer (far from the substrate) in the fluorosilicon-nano-ceramic hybrid coating decreases, that is, the k value decreases, and vice versa, the k value increases.

[0015] In some embodiments, the application also provides a preparation method of a fluorosilicon resin, including the following steps: Step S1: mixing methyl trifluoropropyl siloxane and tetramethyl tetravinyl cyclosiloxane according to a molar ratio of 70-95:5-30 to obtain a first mixture; Step S2: mixing the first mixture of step S1 and an ethanol solvent according to a mass ratio of 2-6:4-8 to obtain a second mixture; adding 92% formic acid to the second mixture in a volume ratio of the second mixture to catalyze hydrolysis, and reacting under ultrasonic dispersion to form a fluorosilicon resin; the temperature of ultrasonic dispersion is 25-30 DEG C, the time is 30-40 min, and the frequency is 40 kHz. By adopting fluorine and organic silicon resin copolymerization to form a fluorosilicon resin, the alkoxy and fluorine can be covalently bonded to form a composite structure, the excellent heat and cold resistance of the organic silicon resin is maintained, and the solvent resistance, aging resistance and extremely low surface energy of the fluorine compound are combined, so that the prepared coating has high cleanliness, wide temperature range adaptability and low process cost.

[0016] In some embodiments, by adjusting the mass ratio of fluorosilicon resin and nano ceramic in the raw material, the mass proportion of fluorosilicon resin and nano ceramic can be adjusted, for example, when the mass ratio of fluorosilicon resin and nano ceramic is increased, the mass proportion of fluorosilicon resin is increased and the mass proportion of nano ceramic is reduced, and when other conditions remain unchanged, the corresponding a value is also increased and the b value is reduced.

[0017] In some embodiments, the surface of the fluorosilicon-nano ceramic hybrid coating also has a silicon dioxide oxidation film, which is formed after the fluorosilicon resin is heat treated and combined with oxygen in the air, and can improve the stability of the fluorosilicon-nano ceramic hybrid coating and further improve the cleanliness and temperature range adaptability of the coating. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 A cross-sectional structure schematic diagram of a fluorosilicon-nano ceramic hybrid coating provided for example 1 of the present application; wherein 1 is a silicon dioxide oxidation film, 2 is a fluorosilicon-nano ceramic hybrid coating, and 3 is a substrate; Figure 2 A fluorosilicon-nano ceramic hybrid coating preparation process flowchart provided for example 1 of the present application; Figure 3 A distribution schematic diagram of surface resistance measurement points provided by the present application. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the following combines examples to further explain the present application. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0020] Example 1 Methyltrifluoropropylsiloxane and tetramethyltetra-vinylcyclotetrasiloxane with a molar ratio of 75:25 are weighed, mixed, and then added to ethanol with a mass ratio of 6:4 to obtain a mixture. The mixture is catalytically hydrolyzed with 92% formic acid relative to the volume of the mixture, ultrasonically dispersed at 30℃ and a frequency of 40 kHz for 30 min, and then copolymerized to form a fluorosilicon resin prepolymer.

[0021] Zirconium oxide and silicon dioxide are mixed in a mass ratio of 70:30 to form a nano-ceramic powder, wherein the particle size of the nano-ceramic powder is 50 nm.

[0022] The fluorosilicon resin prepolymer, nano-ceramic powder (particle size 50 nm), and ethanol solvent are mixed in a mass ratio of 5:3:92 to obtain a mixture. The mixture is catalytically hydrolyzed with 92% formic acid relative to the volume of the mixture, ultrasonically dispersed at 30℃ and a frequency of 40 kHz for 30 min to form a stable sol. The sol is sprayed onto the surface of the substrate at 60℃ using a conventional air spraying device to form a wet film. The wet film is subjected to three curing heat treatments, with the first heat treatment at a curing temperature of 80℃ for 120 min, the second heat treatment at a curing temperature of 150℃ for 60 min, and the third heat treatment at a curing temperature of 200℃ for 30 min.

[0023] The fluorosilicon-nano ceramic hybrid coating of the present embodiment includes fluorosilicon resin and nano ceramic; the fluorosilicon-nano ceramic hybrid coating is arranged on a substrate; the thickness of the fluorosilicon-nano ceramic hybrid coating is 60 μm, wherein in a region x μm away from the substrate, the mass percentage of the fluorosilicon resin is y1%, and the mass percentage of the nano ceramic is y2%; y1 = 70-0.5x, 40≤y1≤70; y2 = 0.5x+30, 30≤y2≤60.

[0024] Example 2 The fluorosilicon-nano ceramic hybrid coating of the present embodiment differs from that of Example 1 only in that in a region x μm away from the substrate, the mass percentage of the fluorosilicon resin is y1%, and the mass percentage of the nano ceramic is y2%; y1 = 75-0.25x, 60≤y1≤75; y2 = 0.25x+25, 25≤y2≤40.

[0025] Example 3 The fluorosilicon-nano ceramic hybrid coating of the present embodiment differs from that of Example 1 only in that in a region x μm away from the substrate, the mass percentage of the fluorosilicon resin is y1%, and the mass percentage of the nano ceramic is y2%; y1 = 85-0.25x, 70≤y1≤85; y2 = 0.25x+15, 15≤y2≤30.

[0026] Example 4 The fluorosilicon-nanoceramic hybrid coating of the embodiment differs from the embodiment 1 only in that: in the region of x μm from the substrate, the mass percentage of the fluorosilicon resin is y1%, and the mass percentage of the nanoceramic is y2%; y1 = 90-0.25x, 75≤y1≤90; y2 = 0.25x+10, 10≤y2≤25.

[0027] Embodiment 5 The fluorosilicon-nanoceramic hybrid coating of the embodiment differs from the embodiment 1 only in that: the thickness of the fluorosilicon-nanoceramic hybrid coating is 90 μm.

[0028] Embodiment 6 The fluorosilicon-nanoceramic hybrid coating of the embodiment differs from the embodiment 1 only in that: the molar ratio of the methyltrifluoropropylsiloxane to the tetramethyltetra-vinylcyclotetrasiloxane is 65:35.

[0029] Embodiment 7 The fluorosilicon-nanoceramic hybrid coating of the embodiment differs from the embodiment 1 only in that: the mass ratio of the zirconium oxide to the silicon dioxide is 85:15.

[0030] Embodiment 8 The fluorosilicon-nanoceramic hybrid coating of the embodiment differs from the embodiment 1 only in that: the particle size of the nanoceramic is 60 nm.

[0031] Comparative Example 1 Compared with the preparation method of the embodiment 1, the difference is that the fluorosilicon resin is replaced by a fluorocarbon resin (PFA / PTFE).

[0032] Comparative Example 2 Compared with the preparation method of the embodiment 1, the difference is that the wet film is only subjected to one-time curing heat treatment, the curing temperature is 200 ℃, and the time is 150 min.

[0033] Test Example 1 The coatings of the embodiments and the comparative examples are subjected to extreme temperature test, wafer contamination test, and surface resistance measurement. The extreme temperature test includes low temperature performance test and high temperature aging test. The low temperature performance test is to test the crack resistance and surface resistance change rate of the coating according to ASTM D522, and the condition is -70 ℃. The high temperature aging test is to test the mass loss and particle release amount of the coating under the condition of continuous high temperature at 250 ℃ for 500 h. The wafer contamination test is to load 12-inch wafers in a FOUP wafer box, and to test the metal ion contamination amount (Na + ) and the particle addition amount after 200 cycles. The surface resistance of the coating is tested when the surface temperature of the coating is 60 ℃, and the maximum value and the minimum value of the surface resistance after the test form a range value. The specific test method is as follows: refer to Figure 3The distribution of the surface resistance measurement points is shown in the figure. A 100mm*100mm rectangular area is selected, and 9 test points are arranged in a 3*3 distribution in the rectangular area. The 3 test points in the first row are each 10mm away from the upper edge of the rectangular area, the 3 points in the first column are each 10mm away from the left edge of the rectangular area, the 3 test points in the third row are each 10mm away from the lower edge of the rectangular area, and the 3 test points in the third column are each 10mm away from the right edge of the rectangular area. The vertical distance between adjacent rows of test points is 40mm, and the horizontal distance between adjacent columns of test points is 40mm. Each point is measured 3 times, with an interval of 1 hour between each test, and a total of 9 points are measured.

[0034] Table 1

[0035] As can be seen from the above table, the fluorosilicon-nanoceramic hybrid coating prepared in the embodiment has high cleanliness, wide temperature range adaptability and low process cost. When the fluorosilicon resin and the nanoceramic are compounded and hybridized and arranged on the substrate, cracks can be avoided under low temperature conditions, and the surface resistance change rate can be small. Under high temperature conditions, the coating mass loss and particle release amount can be reduced, and thus the coating has high cleanliness and wide temperature range adaptability. During the storage and transportation of wafers, when a semiconductor carrier coated with a fluorosilicon-nanoceramic hybrid coating is used, the metal ion pollution amount (Na + ) and the particle addition amount can be reduced, and thus the coating has high cleanliness. In addition, the surface resistance of the fluorosilicon-nanoceramic hybrid coating is small, which can avoid the accumulation of static electricity and reduce particle adsorption, so that the coating has high cleanliness. The use of the fluorosilicon-nanoceramic hybrid coating can also reduce the process cost, and further enable the fluorosilicon-nanoceramic hybrid coating to have high cleanliness, wide temperature range adaptability and low process cost.

[0036] Test Example 2 Table 2

[0037] As can be seen from the above table, the fluorosilicon-nanoceramic hybrid coating prepared in the embodiment has high cleanliness and wide temperature range adaptability. When the fluorosilicon resin and the nanoceramic are compounded and hybridized and arranged on the substrate, the surface resistance change rate can be small under low temperature conditions, thereby reducing the accumulation of static electricity and reducing particle adsorption. Under high temperature conditions, the coating particle release amount can be reduced, and thus the coating has high cleanliness and wide temperature range adaptability. During the storage and transportation of wafers, when a semiconductor carrier coated with a fluorosilicon-nanoceramic hybrid coating is used, the metal ion pollution amount (Na + ) and the particle addition amount can be reduced, and thus the coating has high cleanliness.

[0038] In particular, when the nano-ceramic content is high at the surface far from the substrate, the coating can have high surface smoothness, electrical insulation, so that during the storage and transmission of the wafer, the particle pollution caused by friction can be reduced and the particle adsorption can be reduced, thereby the coating has high cleanliness; when the fluorosilicone content is high near the substrate, the coating can have elasticity, reduce the stress caused by thermal expansion and contraction at extreme temperature changes, thereby the coating can have wide temperature range adaptability; especially, when the mass ratio of fluorosilicone and nano-ceramic in the fluorosilicone-nano-ceramic hybrid coating meets: the fluorosilicone-nano-ceramic hybrid coating is arranged on the substrate; the thickness of the fluorosilicone-nano-ceramic hybrid coating is 60 μm, wherein in the region of x μm away from the substrate, the mass ratio of fluorosilicone is y1%, and the mass ratio of nano-ceramic is y2%; y1=75-0.25x, 60≤y1≤75; y2=0.25x+25, 25≤y2≤40, the fluorosilicone-nano-ceramic hybrid coating can have high cleanliness and wide temperature range adaptability.

Claims

1. A fluorosilicon-nanoceramic hybrid coating, characterized in that, The fluorosilicon-nanoceramic hybrid coating is disposed on a substrate; In a region x microns away from the substrate in the fluorosilicon-nanoceramic hybrid coating, the mass percentage of the fluorosilicon resin is y1%, and the mass percentage of the nanoceramic is y2%; y1=a-kx, y2=kx+b, 70≤a≤90, 10≤b≤30.

2. The fluoro-silicon-nanoceramic hybrid coating of claim 1, wherein, 75≤a≤85, 15≤b≤25.

3. The fluoro-silicon-nanoceramic hybrid coating of claim 1, wherein, 40≤y1≤90; 10≤y2≤60.

4. The fluoro-silicon-nanoceramic hybrid coating of claim 2, wherein, The thickness of the fluorosilicon-nanoceramic hybrid coating is h microns, 50≤h≤80, and 0≤x≤h.

5. The fluoro-silicon-nanoceramic hybrid coating of claim 3, wherein, The fluorosilicon resin is copolymerized from methyl trifluoropropyl siloxane and tetramethyl tetravinyl cyclosiloxane; the molar ratio of the methyl trifluoropropyl siloxane to the tetramethyl tetravinyl cyclosiloxane is 70-95:5-30.

6. The fluoro-silicon-nanoceramic hybrid coating of claim 3, wherein, The nanoceramic includes zirconium oxide and silicon dioxide; the mass ratio of the zirconium oxide to the silicon dioxide is 70-80:20-30.

7. The fluorosilicon-nanoceramic hybrid coating of claim 6, wherein, The particle size of the nanoceramic is 10-50 nm.

8. The method for preparing the fluorosilicon-nanoceramic hybrid coating according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: Step S1: the fluorosilicon resin, the nanoceramic, and an ethanol solvent are mixed in a mass ratio of 5:3:92 to obtain a mixture; 92% formic acid is added to the mixture to catalyze hydrolysis, and ultrasonic dispersion is performed to form a stable sol; the ultrasonic dispersion is performed at a temperature of 25-30°C for 30-40 min at a frequency of 40 kHz; Step S2: the stable sol is sprayed on the surface of the substrate to form a wet film; the temperature of the substrate during spraying is 60-80°C, and the thickness of the wet film is 50-80 microns; Step S3: the wet film is subjected to a three-time heat treatment curing process, including: the first-time heat treatment is performed at a curing temperature of 70-80°C for 120-150 min; the second-time heat treatment is performed at a curing temperature of 140-160°C for 60-80 min; and the third-time heat treatment is performed at a curing temperature of 180-200°C for 20-40 min.

9. The method of claim 8, wherein the fluorosilicon-nanoceramic hybrid coating is prepared by a process comprising: The preparation method of the fluorosilicon resin comprises the following steps: Step S1: the methyl trifluoropropyl siloxane and the tetramethyl tetravinyl cyclosiloxane are mixed in a molar ratio of 70-95:5-30 to obtain a first mixture; Step S2: the first mixture in step S1 and an ethanol solvent are mixed in a mass ratio of 2-6:4-8 to obtain a second mixture; 92% formic acid is added to the second mixture to catalyze hydrolysis, and the fluorosilicon resin is formed by reaction under ultrasonic dispersion; the ultrasonic dispersion is performed at a temperature of 25-30°C for 30-40 min at a frequency of 40 kHz.

10. A semiconductor carrier, characterized by The inner surface of the semiconductor carrier is coated with the fluorosilicon-nanoceramic hybrid coating in any one of claims 1-7.

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