Surface treatment method and surface-treated substrate

Abstract

A surface treatment method according to the present invention comprises: a step for forming a coating film of an organosilicon compound on the surface of a substrate; a step for heating the substrate; a step for bringing the coating film into contact with a medium containing water to form a water-repellent treatment layer; and a step for drying the water-repellent treatment layer.

Description

Surface treatment method and surface-treated substrate

[0001] The present invention relates to a surface treatment method and a surface-treated substrate.

[0002] Film technologies such as photolithography are used to form or microfabricate microelements in various fields, such as the manufacture of semiconductor integrated circuits such as LSIs, display surfaces of FPDs, and circuit boards such as color filters and thermal heads. Generally, a photoresist film is formed by applying a resist to the surface of a substrate, a predetermined pattern is exposed to the photoresist film by photolithography, and the substrate on which the exposed photoresist film is laminated is then immersed in a developer for development, thereby forming a predetermined resist pattern on the substrate. The patterned film on which the resist pattern is formed is used as an etching mask or the like to form or microfabricate microelements.

[0003] In order to improve the adhesion between substrate and photoresist film, the method of forming a water-repellent coating on the surface of substrate is carried out to surface treat the substrate.For example, as the method of surface treating substrate, the hydrophobic organosilane or hydrophobic polyorganosiloxane having silanol group or silicon atom-bonded hydrolyzable group is attached to the coating containing polysilazane formed on the surface of substrate, then the substrate is heated, this coating is converted into silica layer, and organosilane or polyorganosiloxane is bonded to the silica of the silica layer, so as to form a water-repellent silica layer, the water-repellent treatment method of the surface of substrate is disclosed (for example, see Patent Document 1).

[0004] Japanese Patent Application Publication No. 2008-237957

[0005] However, the method of Patent Document 1 has a problem in that the contact angle of the water-repellent silica layer with water is too high, so even if an attempt is made to form a resist pattern by applying a resist to the surface of the water-repellent silica layer, the resist is repelled from the water-repellent silica layer, making it impossible to form a photoresist film on the surface of the water-repellent silica layer.

[0006] An object of one aspect of the present invention is to provide a surface treatment method that can maintain adhesion between a coating formed on a substrate surface and a resist applied to the coating surface.

[0007] One aspect of the present invention is a surface treatment method comprising the steps of: forming a coating of an organosilicon compound on a surface of a substrate; heating the substrate; bringing the coating into contact with a medium containing water to form a water-repellent treatment layer; and drying the water-repellent treatment layer.

[0008] The surface treatment method according to one aspect of the present invention can maintain adhesion between a coating formed on a substrate surface and a resist applied to the coating surface.

[0009] 1 is a flowchart showing an example of a surface treatment method according to an embodiment of the present invention; FIG. 2 is a cross-sectional view showing an example of a state in which a coating of an organosilicon compound is formed on the surface of a substrate; FIG. 3 is an explanatory view explaining the formation of a coating when hexamethyldisilazane is used as the organosilicon compound; FIG. 4 is a cross-sectional view showing an example of a state in which a water-repellent treatment layer is formed on the surface of a substrate; FIG. 5 is a diagram showing the water contact angle of a coating after a substrate is immersed in HMDS to form a coating of HMDS on the surface of the substrate; and FIG. 6 is a diagram showing the water contact angle of a water-repellent treatment layer formed by immersing a substrate having a coating formed on its surface in pure water.

[0010] Hereinafter, embodiments of the present invention will be described in detail. To facilitate understanding of the description, the same components in each drawing are denoted by the same reference numerals, and duplicate descriptions will be omitted. The scale of each component in the drawings may differ from the actual scale. In this specification, unless otherwise specified, the symbol "to" indicating a range of values ​​means that the values ​​before and after it are included as the lower and upper limits.

[0011] <Surface Treatment Method> A surface treatment method according to an embodiment of the present invention (hereinafter simply referred to as "this embodiment") will be described. The surface treatment method according to this embodiment adjusts the magnitude of the water contact angle by reducing the contact angle with water (hereinafter simply referred to as "water contact angle") of a hydrophobic coating formed on the surface of a substrate when the substrate surface is subjected to a water-repellent treatment before the resist is applied to the surface side of the substrate. This prevents the resist from being repelled from the coating surface when the resist is applied to the coating surface, and allows the coating formed on the substrate surface to maintain adhesion to the resist applied to its surface.

[0012] 1 is a flowchart showing an example of a surface treatment method according to the present embodiment. As shown in FIG. 1, in the surface treatment method according to the present embodiment, a coating containing an organosilicon compound is formed on a substrate (coating formation step: step S11).

[0013] 2, by bringing an organosilicon compound into contact with a substrate 10, a coating 20 containing the organosilicon compound is formed on the surface of the substrate 10. The coating 20 may be formed on the entire surface of the substrate 10, or may be formed only on both main surfaces of the substrate 10.

[0014] The substrate 10 may have hydroxyl groups (OH groups) on its surface. The OH groups on the surface of the substrate 10 may be generated due to the adsorption of moisture, such as water vapor, from the ambient air. Alternatively, the OH groups may be generated on the surface of an oxide film made of oxide that is naturally generated when the components that make up the substrate 10 are oxidized. Furthermore, the OH groups may be bonded to the surface of the substrate 10 by any method.

[0015] When the substrate 10 is a substrate containing silicon, such as silica, in the atmosphere, the surface of the substrate 10 usually has an oxide film formed thereon, such as an oxide of Si (SiO ２ ) is generated, and silanol groups (HO-Si≡) are present. When silanol groups are present on the surface of the substrate 10, the surface of the substrate 10 becomes hydrophilic. When resist is directly applied to the surface of the substrate 10, the developer may penetrate between the substrate 10 and the resist during development, making the resist pattern more likely to peel off. In particular, when the developer contains water as its main component, the developer may easily penetrate between the substrate 10 and the resist, making the resist pattern more likely to peel off. The organosilicon compound contained in the coating 20 contains a hydrophobic methyl group (-CH ３ ) bonded to the surface of the substrate 10, and by reacting with the silanol groups on the surface of the substrate 10, the silanol groups are covered with methyl groups, so that the surface of the substrate 10 becomes hydrophobic. For example, as shown in FIG. 3, when the organosilicon compound is hexamethyldisilazane (HMDS), the Si of HMDS bonds with the silanol groups on the surface of the substrate 10, and the silanol groups become -OSi(CH ３ ) ３The resulting methyl group is covered with a methyl group, which becomes a hydrophobic group. Therefore, the coating 20 formed on the surface of the substrate 10 has hydrophobic properties. By forming the coating 20 on the surface of the substrate 10 and making the surface of the substrate 10 hydrophobic, it is possible to prevent the developer from penetrating between the coating 20 and the resist applied to its surface.

[0016] The substrate 10 may be made of various inorganic and organic materials, and may be a material on whose surface OH groups can be generated. Materials for the inorganic substrate include silicon (Si), silica (SiO ２ ), silicon carbide (SiC), sapphire, compound semiconductors, titanium, titanium alloys, silver, copper, aluminum, vanadium, chromium, niobium, tantalum, nickel, zinc, zirconium, molybdenum, tungsten, ruthenium, rhodium, palladium, hafnium, steel, stainless steel, duralumin, and glass. Organic substrates include synthetic resins such as polyethylene resin, polypropylene resin, acrylic resin, polyamide resin, polyester resin, polycarbonate resin, polyvinyl alcohol, poval resin, ABS resin, polyimide resin, epoxy resin, and polyurethane resin, as well as natural materials such as synthetic wood, bamboo, and wood. These materials may be used alone or in combination of two or more. Among these, examples of substrate materials that can generate OH groups on the surface include silicon, silica, silicon carbide, sapphire, compound semiconductors, titanium, silver, copper, aluminum, vanadium, chromium, niobium, tantalum, nickel, zinc, zirconium, molybdenum, tungsten, ruthenium, rhodium, palladium, and hafnium.

[0017] The substrate 10 has a plate-like shape, but may have any other suitable shape depending on the intended use of the article, such as a tube, sheet, film, foil, tape, block, or cloth.

[0018] The substrate 10 is preferably washed in advance to remove particles adhering to the surface of the substrate 10, leaving the substrate free of particles. Examples of cleaning methods that can be used include shower cleaning, immersion cleaning, scrub cleaning, steam cleaning, spin cleaning, and ultrasonic cleaning. These cleaning methods may be used alone or in combination of two or more. Water or a cleaning solution is generally used for cleaning. An acidic aqueous solution or an alkaline aqueous solution may be used as the cleaning solution.

[0019] The method for forming the coating 20 on the substrate 10 is not particularly limited, and any appropriate method may be used. For example, dip coating, spin coating, vaporization, roll coating, flow coating, inkjet printing, spray coating, printing, bar coating, and gravure printing can be used. In the dip coating method, the substrate 10 is immersed in a solution containing an organosilicon compound. In the spin coating method, a solution containing an organosilicon compound is dropped approximately at the center of the surface (main surface) of the substrate 10, and then the substrate 10 is rotated at high speed around its axis to coat the solution containing the organosilicon compound almost uniformly on the surface of the substrate 10. In the vaporization method, vapor containing the vaporized organosilicon compound is adsorbed onto the surface of the substrate 10. Among these, the dip coating method is preferred because it allows the coating 20 to be formed on a large number of substrates 10 and is easy to form the coating 20 on the substrate 10.

[0020] The water contact angle of the coating 20 may be, for example, 85° or more, depending on the conditions under which the coating 20 is formed.

[0021] The method for measuring the water contact angle is not particularly limited, and a general measurement method may be used. For example, a water droplet is dropped on the surface of the coating 20 formed on the surface of the substrate 10 at 25°C, and the contact angle of the water droplet is measured using a QI optical mirror contact angle meter. The water contact angle can be calculated by determining the radius r and height h of the droplet and substituting these values ​​into the following equation (2), which is a conversion of the following equation (1). tan θ １ =h / r...(1) θ=2arctan(h / r)...(2)

[0022] The water contact angle can also be determined using the θ / 2 method. The θ / 2 method involves measuring the angle θ1 of a line connecting the left and right endpoints of a droplet dropped on the surface of the coating 20 to the apex of the droplet in a cross section passing through the apex, with the surface of the coating 20, and then doubling this angle θ1 to determine the contact angle θ. The contact angle θ determined by the θ / 2 method is defined as the water contact angle.

[0023] The water dropped onto the surface of the coating 20 may be pure water.

[0024] In measuring the water contact angle, a test specimen on which the coating 20 is formed may be used in addition to the substrate 10 on whose surface the coating 20 is formed.

[0025] If the solvent of the solution containing the organosilicon compound remains on the surface of the coating 20, the water contact angle of the coating 20 is measured after the solvent has been removed.

[0026] The thickness of the coating 20 can be appropriately set depending on the purpose. For example, the thickness of the coating 20 can be set so that the thickness of the water-repellent treatment layer 30 (see FIG. 4) after drying in the drying step (step S14) described below is preferably 0.1 nm to 10 nm.

[0027] When forming the coating 20 of the organosilicon compound on the substrate 10, the time for which the organosilicon compound is brought into contact with the substrate 10 is not particularly limited, and any method may be used depending on the type of organosilicon compound, the method for forming the coating 20 on the substrate 10, etc.

[0028] When a dip coating method is used as a method for forming the coating 20 on the substrate 10, the immersion time for immersing the substrate 10 in a solution containing an organosilicon compound is preferably 20 minutes or longer. When using the dip coating method, in the initial stage of immersing the substrate 10 in a solution containing an organosilicon compound, there are many areas on the surface of the substrate 10 where the organosilicon compound is not adsorbed, and the water contact angle of the coating 20 formed on the surface of the substrate 10 increases slowly until the water contact angle of the coating 20 reaches approximately 85°, which may result in insufficient formation of the coating 20. As a result, there are areas on the surface of the substrate 10 where the water contact angle of the coating 20 is unstable, which may result in variations in the water contact angle of the coating 20. If the immersion time for immersing the substrate 10 in a solution containing an organosilicon compound is 20 minutes or longer, the organosilicon compound is sufficiently adsorbed on the surface of the substrate 10, the coating 20 is formed over almost the entire surface of the substrate 10, and the water contact angle of the coating 20 can be approximately constant at approximately 85°.

[0029] The upper limit of the immersion time for immersing the substrate 10 in the solution containing the organosilicon compound is not particularly limited, but may be set to, for example, about 90 minutes in consideration of the degree of formation of the coating 20 and productivity, etc. When the coating 20 is formed on the entire surface of the substrate 10, the water contact angle of the coating 20 becomes substantially constant at about 85° and does not increase further in proportion to the immersion time, and therefore, an effect commensurate with the immersion time cannot be obtained.

[0030] The organosilicon compound is a compound having a silicon-nitrogen bond, and functions as a silane coupling agent or a silylating agent. Examples of the organosilicon compound include silylamines such as HMDS, trimethylsilyldimethylamine (TMSDMA), trimethylsilyldiethylamine (TMSDEA), and trimethylsilylimidazole (TMSI), as well as silylamides such as 3-glycidyloxypropyltrimethoxysilane, 3-(trimethoxysilyl)propyl methacrylate, 3-aminopropyltriethoxysilane, and (3-mercaptopropyl)trimethoxysilane. Among these, the organosilicon compound is preferably HMDS. HMDS has a methyl group (-CH ) that is hydrophobic and binds to the surface of the substrate 10. ３) and reacts with two silanol groups on the surface of the substrate 10, thereby covering the silanol groups with methyl groups, making it easy to make the surface of the substrate 10 hydrophobic.

[0031] Next, as shown in FIG. 1, the substrate 10 having the coating 20 formed on its surface is heated (heating step: step S12).

[0032] The heating method is not particularly limited, and any general heating method for coating films may be used as long as it can remove the solvent in the coating film 20. For example, a heater may be used as the heating method.

[0033] The heating temperature may be within a range that can remove the solvent in the coating 20 and does not cause thermal damage to the substrate 10 and the coating 20, and may be, for example, 70°C to 120°C. If the heating temperature is 70°C to 120°C, it is possible to remove the solvent in the coating 20 while suppressing thermal damage to the substrate 10 and the coating 20. The heating temperature is preferably 75°C or higher, and more preferably 80°C or higher.

[0034] The heating time may be within a range that allows the solvent in the coating 20 to be removed without causing thermal damage to the substrate 10 and the coating 20, and may be, for example, 5 minutes to 30 hours. If the heating time is 5 minutes to 30 hours, it is possible to remove the solvent in the coating 20 while suppressing thermal damage to the substrate 10 and the coating 20. The heating time is preferably 30 minutes or more, and more preferably 1 hour or more.

[0035] Next, the coating 20 is brought into contact with a medium containing water (medium contact step: step S13).

[0036] Although water that is commonly used may be used, it is preferable to use water that is highly pure and contains little or no impurities, such as pure water or ultrapure water.

[0037] The organosilicon compound contained in the coating 20 tends to react easily with water. By exposing the substrate 10 having the coating 20 formed on its surface to a high-humidity environment and bringing the coating 20 into contact with a medium containing water, the organosilicon compound contained in the coating 20 is hydrolyzed. As a result, as shown in FIG. 4 , a substrate 10 is obtained having a water-repellent treatment layer 30 formed on its surface, where the organosilicon compound contained in the coating 20 has been hydrolyzed. It is believed that the hydrolysis of the organosilicon compound reduces the area of ​​the organosilicon compound present on the surface of the coating 20, and the organosilicon compound is present in a sparse state on the surface of the coating 20. Therefore, it can be said that the area of ​​the organosilicon compound present on the surface of the water-repellent treatment layer 30 is smaller than that of the coating 20.

[0038] The high humidity environment may be, for example, RH 70% or higher.

[0039] When the organosilicon compound contained in the coating 20 is hydrolyzed, trimethylsilanol (TMS), hexamethylenedisiloxane (HMDSO), etc. are generated, and ammonia (NH ３ ) is generated. TMS, HMDSO and NH ３ Compounds resulting from the hydrolysis of the organosilicon compound, such as , separate from the surface of the coating 20.

[0040] Among organosilicon compounds, HMDS has a property of being particularly reactive with water. Therefore, when the coating 20 contains HMDS as an organosilicon compound, the hydrolysis of the HMDS contained in the coating 20 is more likely to proceed by bringing the coating 20 into contact with a medium containing water.

[0041] The hydrolysis of the organosilicon compound contained in the coating 20 can be confirmed by the presence of TMS, HMDSO, or NH ３ The concentration of can be confirmed by analysis using an analytical device generally used for qualitative or quantitative analysis of compounds, such as a Fourier transform infrared spectrophotometer (FT-IR), a reflectance-enhanced spectrophotometer (RAS), a photoacoustic spectrophotometer (PAS), or an X-ray photoelectron spectrophotometer (XPS).

[0042] The water-containing medium may be only water or water vapor, and in addition to water and water vapor, an alcohol aqueous solution or the like can also be used as the water-containing medium.

[0043] The method for contacting the coating 20 with a water-containing medium is not particularly limited, and any appropriate method may be used as long as it is possible to expose the substrate 10 having the coating 20 formed on its surface to a high-humidity environment and bring the coating 20 into contact with a water-containing medium. Examples of methods for contacting the coating 20 with a water-containing medium include dip coating, evaporation, and spray coating. Among these, dip coating is preferred because it allows the entire surface of the coating 20 to easily come into contact with water almost uniformly.

[0044] When using the dip coating method, the speed at which the substrate 10 having the coating 20 formed on its surface is immersed in the medium and pulled up is not particularly limited, and may be any speed appropriate depending on the size of the substrate 10, the type of coating 20, etc.

[0045] The temperature of the water-containing medium is not particularly limited and may be room temperature.

[0046] The contact time when the coating 20 is brought into contact with water is preferably 5 minutes to 30 hours. If the contact time is 5 minutes or more, the organosilicon compound contained in the coating 20 can be sufficiently hydrolyzed. If the contact time is 30 hours or less, it is possible to prevent the organosilicon compound of the coating 20 from being hydrolyzed and losing the water-repellent properties of the coating 20, and it is also possible to reduce the water contact angle of the surface of the coating 20. The immersion time is preferably 1 hour or more, and more preferably 3 hours or more.

[0047] Next, as shown in FIG. 1, the substrate 10 on which the water-repellent treatment layer 30 has been formed is dried to remove solvents, such as water, remaining in the medium adhering to the water-repellent treatment layer 30 (drying step: step S14).

[0048] The drying method is not particularly limited, and may be a general drying method for a coating film as long as it can remove the solvent in the medium remaining on the water-repellent treatment layer 30. For example, a heater or the like may be used as the drying method.

[0049] The drying temperature may be within a range that can remove the solvent in the water-repellent treatment layer 30 and does not cause heat damage to the substrate 10 and the water-repellent treatment layer 30, and may be, for example, 80°C to 100°C. If the drying temperature is 80°C to 100°C, it is possible to remove the solvent in the medium that remains on the water-repellent treatment layer 30 while suppressing heat damage to the substrate 10 and the water-repellent treatment layer 30. The drying temperature is preferably 85°C or higher, and more preferably 90°C or higher.

[0050] The drying time may be within a range that can remove the solvent in the medium remaining on the water-repellent treatment layer 30 and that does not cause heat damage to the substrate 10 and the water-repellent treatment layer 30, and is preferably, for example, 5 minutes to 30 hours. If the drying time is 5 minutes to 30 hours, it is possible to remove the solvent in the water-repellent treatment layer 30 while suppressing heat damage to the substrate 10 and the water-repellent treatment layer 30. The drying time is preferably 1 hour or longer, and more preferably 80°C or higher.

[0051] In the drying step, the water-repellent treatment layer 30 is dried to remove the solvent in the medium remaining on the water-repellent treatment layer 30, thereby obtaining a substrate 10 having a water-repellent treatment layer 30 formed on its surface, in which at least a portion of the organosilicon compound contained in the coating 20 has been hydrolyzed, as shown in Figure 4.

[0052] The water contact angle of the water-repellent treatment layer 30 after drying is preferably 60° or more and less than 85°. The water contact angle of the water-repellent treatment layer 30 after drying is more preferably 82° or less. If the water contact angle is 60° or more, the water-repellent treatment layer 30 can exhibit hydrophobicity. If the water contact angle is less than 85°, the resist applied to the surface of the water-repellent treatment layer 30 is prevented from being repelled, and the water-repellent treatment layer 30 can maintain adhesion to the resist.

[0053] The water contact angle of the water-repellent treatment layer 30 can be measured using the same method as that used to measure the water contact angle of the coating film 20 described above.

[0054] The surface treatment method according to this embodiment provides a surface-treated substrate 1, as shown in FIG. 4, which includes a substrate 10 and a water-repellent treatment layer 30 formed on the surface of the substrate 10, the water-repellent treatment layer 30 being formed by hydrolysis of the organosilicon compound in the coating 20 and having a water contact angle of 60° or more and less than 85° after drying.

[0055] Thus, the surface treatment method according to this embodiment includes a coating formation step (step S11), a medium contact step (step S13), and a drying step (step S14). In the surface treatment method according to this embodiment, a coating 20 is formed on the surface of the substrate 10 in the coating formation step (step S11), the organosilicon compound contained in the coating 20 is hydrolyzed in the medium contact step (step S13), and the water-repellent treatment layer 30 formed after medium contact is dried in the drying step (step S14). The surface treatment method according to this embodiment can reduce the water contact angle of the surface of the water-repellent treatment layer 30 after drying by hydrolyzing the organosilicon compound contained in the coating 20. Therefore, the surface treatment method according to this embodiment forms a water-repellent treatment layer 30 on the surface of the substrate 10, and when a resist is applied to the surface of the water-repellent treatment layer 30 formed on the surface of the substrate 10, the adhesion between the water-repellent treatment layer 30 formed on the surface of the substrate 10 and the resist applied to the surface can be maintained.

[0056] Furthermore, in the surface treatment method according to this embodiment, a water-repellent treatment layer 30 is formed on the surface of the substrate 10, so resist is not applied to the surface of the substrate 10. If resist is applied directly to the surface of the substrate 10, the adhesion between the substrate 10 and the resist is weak, and therefore, during development, the developer may penetrate into the interface between the substrate 10 and the patterned film having the resist pattern formed by exposing the resist, potentially causing the patterned film to peel off from the substrate 10. In particular, when the developer contains water as its main component, the developer easily penetrates between the substrate 10 and the patterned film. In the surface treatment method according to this embodiment, a water-repellent treatment layer 30 is formed on the surface of the substrate 10, so resist is applied to the surface of the water-repellent treatment layer 30. Because the adhesion between the water-repellent treatment layer 30 and the resist can be maintained, penetration of the developer into the interface between the water-repellent treatment layer 30 and the resist can be suppressed during development. Therefore, the surface treatment method according to this embodiment can suppress peeling of the resist from the water-repellent treatment layer 30 during development.

[0057] Furthermore, in the surface treatment method according to this embodiment, the water contact angle of the surface of the coating 20 after drying can be adjusted to any desired value by contacting the surface of the coating 20 with water and adjusting the contact time in the medium contact step, eliminating the need for special equipment and complicated processes. For example, one method for adjusting the water contact angle of the surface of the substrate 10 is to perform oxygen plasma treatment while supplying fluorine. This method requires the design of special equipment and uses fluorine and oxygen as supply gases for each treatment, resulting in high product costs and a heavy environmental impact. Another method for adjusting the water contact angle is to select a silane coupling agent with a different reaction mechanism. This method requires the preparation of multiple silane coupling agents to adjust the water contact angle, making the surface treatment process complicated. In the surface treatment method according to this embodiment, the water contact angle of the surface of the coating 20 after drying can be adjusted to any desired value by contacting the surface of the coating 20 with water and adjusting the contact time in the medium contact step. The surface treatment method according to this embodiment does not require the use of special equipment or complicated processes, and therefore can adjust the water contact angle on the surface of the water-repellent treatment layer 30 efficiently, easily, and at low cost while minimizing the burden on the environment.

[0058] As described above, the surface treatment method according to this embodiment can maintain adhesion between the water-repellent treatment layer 30 formed on the surface of the substrate 10 and the resist applied to that surface while suppressing peeling of the resist from the substrate 10 during development, and therefore can be suitably used when forming a resist pattern using photolithography to form microelements or perform microfabrication. Therefore, the surface treatment method according to this embodiment can be suitably used when manufacturing semiconductor integrated circuits such as LSIs, display surfaces of FPDs, circuit boards such as color filters and thermal heads, etc.

[0059] Although the embodiments have been described above, they are presented as examples and the present invention is not limited to the above embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, or modifications can be made without departing from the spirit of the invention. The above embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as set forth in the claims.

[0060] The present embodiment will be described in more detail below with reference to examples, but the present embodiment is not limited to these examples.

[0061] <Surface Treatment> [Example 1] Substrate (SiO ２) was immersed in a container for 30 minutes in HMDS, a silane coupling agent. With HMDS coated on the surface of the substrate, the substrate was removed from the HMDS and heat-treated in an oven at 85°C for 10 minutes to form a coating of HMDS on the surface of the substrate. The substrate with the coating formed on its surface was then immersed in pure water in a container for 1 hour to form a water-repellent layer by hydrolyzing at least a portion of the HMDS contained in the coating. The substrate with the water-repellent layer formed on its surface was then removed from the pure water and dried in an oven at 100°C for 30 minutes. Figure 5 shows the water contact angle of the coating after the substrate was immersed in HMDS to form an HMDS coating on the surface of the substrate. Figure 6 shows the water contact angle of the water-repellent layer formed by immersing the substrate with the coating formed on its surface in pure water. If the water contact angle is 85° or more, the resist applied to the surface of the substrate, coating, or water-repellent treatment layer will be repelled, so a water contact angle of less than 85° can be considered to be good.

[0062] [Examples 2 to 6, Comparative Example 1] The surface treatment of the substrate was carried out in the same manner as in Example 1, except that the immersion time in HMDS in Example 1 was changed to the following HMDS immersion times. The water contact angles of the HMDS coating formed on the substrate surface by immersing the substrate in HMDS and the water-repellent treatment layer formed on the substrate surface are shown in Figure 5. (Immersion time in HMDS) Comparative Example 1: 0 min Example 2: 5 min Example 3: 10 min Example 4: 20 min Example 5: 40 min Example 6: 60 min

[0063] [Examples 1-1 to 1-5, Comparative Example 2] The surface treatment of the substrate was carried out in the same manner as in Example 1, except that the immersion time in pure water in Example 1 was changed to the following immersion times in pure water. The water contact angle of the coating after the substrate on which the coating was formed was immersed in pure water is shown in Figure 6. (Immersion time in pure water) Comparative Example 2: 0 minutes Example 1-1: 4 hours Example 1-2: 8 hours Example 1-3: 15 hours Example 1-4: 35 hours Example 1-5: 54 hours

[0064] As shown in Figure 5, in Examples 1 to 6, the water-repellent treatment layers formed by immersing the coating in pure water had a water contact angle of less than 85°. Also, as shown in Figure 6, in Examples 1-1 to 1-5, the water-repellent treatment layers formed by immersing the coating in pure water had a water contact angle of less than 85°. On the other hand, in Comparative Example 2, the water contact angle of the water-repellent treatment layer was 85° or more.

[0065] Therefore, it was confirmed that, according to the surface treatment method of this embodiment, a coating containing HMDS is formed on the surface of a substrate, and even if the water contact angle of the coating is 85° or more, the water contact angle of the water-repellent treatment layer formed on the surface of the substrate can be adjusted to the range of 45° to 85° by adjusting the immersion time of the coating in pure water. Therefore, by using the surface treatment method of this embodiment, it is possible to maintain adhesion between the water-repellent treatment layer formed on the surface of the substrate and the resist applied to that surface.

[0066] Note that aspects of the present invention are as follows, for example. <1> A surface treatment method comprising the steps of forming a coating of an organosilicon compound on the surface of a substrate, heating the substrate, bringing the coating into contact with a medium containing water to form a water-repellent treatment layer, and drying the water-repellent treatment layer. <2> The surface treatment method according to <1>, wherein the step of bringing the coating into contact with water hydrolyzes the organosilicon compound contained in the coating. <3> The surface treatment method according to <1> or <2>, wherein the organosilicon compound is a compound having a silicon-nitrogen bond. <4> The surface treatment method according to any one of <1> to <3>, wherein the organosilicon compound comprises at least one component selected from the group consisting of hexamethyldisilazane, trimethylsilyldimethylamine, trimethylsilyldiethylamine, trimethylsilylimidazole, 3-glycidyloxypropyltrimethoxysilane, 3-(trimethoxysilyl)propyl methacrylate, 3-aminopropyltriethoxysilane, and (3-mercaptopropyl)trimethoxysilane. <5> The surface treatment method according to any one of <1> to <4>, wherein the substrate comprises at least one material selected from the group consisting of silicon, silica, silicon carbide, sapphire, and compound semiconductors. <6> The surface treatment method according to any one of <1> to <5>, wherein the contact time when the coating is brought into contact with water is 5 minutes to 30 hours. <7> The surface treatment method according to any one of <1> to <6>, wherein the step of forming a coating of an organosilicon compound on the surface of the substrate uses a dip coating method, a spin coating method, or a vaporization method. <8> The surface treatment method according to any one of <1> to <7>, wherein the water contact angle of the water repellent treatment layer after drying is 60° or more and less than 85°. <9> A surface-treated substrate comprising a water repellent treatment layer having an organosilicon compound on a substrate surface, wherein the water contact angle of the water repellent treatment layer after drying is 60° or more and less than 85°.

[0067] This application claims priority based on Japanese Patent Application No. 2024-21675, filed with the Japan Patent Office on February 16, 2024, and incorporates the entire contents of said application by reference.

[0068] 10: Substrate 20: Coating 30: Water-repellent treatment layer

Claims

1. A surface treatment method comprising the steps of: forming a coating of an organosilicon compound on the surface of a substrate; heating the substrate; bringing the coating into contact with a medium containing water to form a water-repellent treatment layer; and drying the water-repellent treatment layer.

2. The surface treatment method according to claim 1, wherein the step of bringing the coating into contact with water hydrolyzes the organosilicon compound contained in the coating.

3. The surface treatment method according to claim 1 or 2, wherein the organosilicon compound is a compound having a silicon-nitrogen bond.

4. The surface treatment method according to claim 1 or 2, wherein the organosilicon compound contains at least one component selected from the group consisting of hexamethyldisilazane, trimethylsilyldimethylamine, trimethylsilyldiethylamine, trimethylsilylimidazole, 3-glycidyloxypropyltrimethoxysilane, 3-(trimethoxysilyl)propyl methacrylate, 3-aminopropyltriethoxysilane, and (3-mercaptopropyl)trimethoxysilane.

5. The surface treatment method according to claim 1 or 2, wherein the substrate comprises at least one material selected from the group consisting of silicon, silica, silicon carbide, sapphire, and compound semiconductors.

6. The surface treatment method according to claim 1 or 2, wherein the contact time when the coating is brought into contact with the water is 5 minutes to 30 hours.

7. The surface treatment method according to claim 1 or 2, wherein the step of forming a coating of an organosilicon compound on the surface of the substrate uses a dip coating method, a spin coating method or a vaporization method.

8. The surface treatment method according to claim 1 or 2, wherein the water contact angle of the water repellent treatment layer after drying is 60° or more and less than 85°.

9. A surface-treated substrate comprising a water-repellent treatment layer containing an organosilicon compound on the surface of the substrate, wherein the water-repellent treatment layer has a water contact angle of 60° or more and less than 85° after drying.

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