Surface treatment composition and method for producing wafer

Abstract

The present invention pertains to a surface treatment composition which is supplied as vapor to the surface of a wafer having a concave–convex pattern on the surface and is used to form a water-repellent protective film on the surface, the surface treatment composition containing a silylating agent and a solvent, wherein the silylating agent contains a silicon compound represented by (R1)3Si-X (R1's are each independently a group selected from the group consisting of a C1-10 hydrocarbon group and a C1-10 hydrocarbon group in which some or all of the hydrogen atoms are substituted with fluorine atoms, and X is an amino group), and the solvent contains at least 75 mass% of a hydrocarbon solvent per 100 mass% of the total amount of the solvent.

Description

Surface treatment composition and wafer manufacturing method

[0001] The present invention relates to a surface treatment composition and a method for producing a wafer.

[0002] Semiconductor devices for networks and digital home appliances are required to achieve ever higher performance, functionality, and lower power consumption. To meet this demand, circuit patterns are becoming increasingly finer. As this miniaturization progresses, pattern collapse of circuit patterns has become a problem. In semiconductor device manufacturing, cleaning processes are frequently used to remove particles and metal impurities, and as a result, cleaning processes account for 30 to 40 percent of the entire semiconductor manufacturing process. In this cleaning process, as the aspect ratio of patterns increases with the miniaturization of semiconductor devices, pattern collapse occurs when the gas-liquid interface passes through the pattern after cleaning or rinsing. This phenomenon is called pattern collapse. Preventing pattern collapse often requires changes to the pattern design and can lead to reduced production yields. Therefore, a method for preventing pattern collapse during the cleaning process is needed.

[0003] Forming a water-repellent protective film on the pattern surface is known to be an effective method for preventing pattern collapse. Since this water-repellent treatment must be performed without drying the pattern surface, a chemical liquid for forming a water-repellent protective film capable of making the pattern surface water-repellent is supplied to the pattern surface in a state where a cleaning liquid or the like is retained, and the water-repellent protective film is formed by replacing the cleaning liquid or the like with the chemical liquid.

[0004] One such technique is known from Patent Document 1. Patent Document 1 describes a surface treatment composition containing a silylating agent, diethyl carbonate, and propylene carbonate as a solvent (Example 5 of Patent Document 1).

[0005] International Publication No. 2019 / 193967

[0006] However, as a result of investigations by the present inventors, it has been found that there is room for improvement in the surface treatment composition described in Patent Document 1 above in terms of ease of increasing the water contact angle.

[0007] After further investigation, the present inventors found that the surface treatment composition is likely to have an increased water contact angle when a silicon compound such as trialkylsilylamine is used as a silylating agent in combination with a hydrocarbon solvent whose content in the solvent is 97% by mass or more. Further investigations revealed that a practically high contact angle can be maintained when the content of the hydrocarbon solvent in the solvent is 75% by mass or more, and thus the present invention was completed.

[0008] According to one aspect of the present invention, there are provided the following surface treatment composition and wafer manufacturing method.

[0009] 1. A surface treatment composition containing a silylating agent and a solvent, which is supplied as a vapor to a surface of a wafer having a textured pattern on the surface and is used to form a water-repellent protective film on the surface, wherein the silylating agent contains a silicon compound represented by formula (1): (R １ ) ３ Si-X (1) (where R １are each independently a group selected from the group consisting of hydrocarbon groups having 1 to 10 carbon atoms and hydrocarbon groups having 1 to 10 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms, and X is an amino group. 2. A surface treatment composition in which the solvent contains 75 mass% or more of a hydrocarbon solvent, based on 100 mass% of the total amount of the solvent. 2. A surface treatment composition in accordance with 1., in which the content of the hydrocarbon solvent is 97 mass% or more, based on 100 mass% of the total amount of the solvent. 3. A surface treatment composition in accordance with 1. or 2., in which the hydrocarbon solvent contains an aromatic hydrocarbon. 4. A surface treatment composition in accordance with any one of 1. to 3., in which the content of the silylating agent is 0.3 mass% or more and 30 mass% or less, based on 100 mass% of the surface treatment composition. 5. A surface treatment composition in accordance with 1. to 4. 5. The surface treatment composition according to any one of 1. to 4., wherein the boiling point difference between the boiling point of the solvent and the boiling point of the silylating agent at 1 atmosphere (boiling point of solvent - boiling point of silylating agent) is 20°C or more. 6. The surface treatment composition according to any one of 1. to 5., wherein the silicon compound comprises one or more selected from the group consisting of trimethylsilyldimethylamine, trimethylsilyldiethylamine, N-(trimethylsilyl)-tert-butylamine, hexamethyldisilazane, and compounds in which at least one trimethylsilyl group of these trimethylsilylamines is substituted with any one of an ethyldimethylsilyl group, a propyldimethylsilyl group, a butyldimethylsilyl group, a hexyldimethylsilyl group, an octyldimethylsilyl group, and a decyldimethylsilyl group. 7. The surface treatment composition according to any one of 1. to 6., wherein the water contact angle of the silicon wafer surface after the surface treatment is greater than 80°, as measured by the following procedure. (Procedure) A smooth silicon wafer having a thermally oxidized film layer on its surface is cleaned by immersing it in a 1% by mass aqueous solution of hydrofluoric acid at 25° C. for 10 minutes, then in pure water at 25° C. for 1 minute, and in 2-propanol (iPA) for 1 minute at 25° C. After cleaning, the silicon wafer is placed horizontally with a puddle of iPA on it, and vapor of the surface treatment composition is supplied to the silicon wafer.Next, the vapor is converted to a liquid state on the surface of the silicon wafer, and the iPA retained on the surface is replaced with the liquid. The silicon wafer is then immersed in iPA at 25°C for 1 minute. Air is then blown onto the silicon wafer to remove the iPA from the surface. The water contact angle is measured on the silicon wafer surface obtained by the above steps using 2 μl of pure water in accordance with JIS R 3257:1999 "Test method for wettability of substrate glass surfaces." 8. The surface treatment composition according to any one of 1. to 7., wherein the surface treatment composition does not contain an acyclic carbonate ester or contains an acyclic carbonate ester in an amount of 2 mass% or less relative to 100 mass% of the surface treatment composition. 9. The surface treatment composition according to any one of 1. to 8., wherein the surface treatment composition does not contain a catalyst or contains a catalyst in an amount of 2 mass% or less relative to 100 mass% of the surface treatment composition. 10. The surface treatment composition according to any one of 1. to 9. 1. The surface treatment composition according to any one of the above items, wherein the number of particles larger than 0.2 μm as measured using a light scattering liquid-borne particle detector is 1.0×10 per mL of the surface treatment composition. ４ 11. The surface treatment composition according to any one of 1. to 10., wherein the total content of Na, Mg, Ca, Mn, Fe, Cu, Li, Al, Cr, Ni, Zn, and Ag in the surface treatment composition is 100 ppb by mass or less, as measured by inductively coupled plasma mass spectrometry. 12. A method for manufacturing a wafer, comprising the steps of: preparing a wafer having a concave-convex pattern on its surface; supplying a cleaning liquid to the surface of the wafer to clean it; and supplying vapor of a surface treatment composition to the surface holding the cleaning liquid, changing the state of the vapor to a liquid on the surface, and replacing the cleaning liquid with the liquid, thereby forming a water-repellent protective film on at least a portion of the surface, wherein the surface treatment composition comprises a silylating agent and a solvent, and the silylating agent comprises a silicon compound represented by formula (1), (R １ ) ３ Si-X (1) (where R １are each independently a group selected from the group consisting of a hydrocarbon group having 1 to 10 carbon atoms and a hydrocarbon group having 1 to 10 carbon atoms in which some or all of the hydrogen atoms are substituted with fluorine atoms, and X is an amino group. 13. A method for manufacturing a wafer according to item 12, wherein the content of the hydrocarbon solvent is 97 mass% or more based on 100 mass% of the total amount of the solvent. 14. A method for manufacturing a wafer according to item 12 or 13, wherein the hydrocarbon solvent in the surface treatment composition comprises an aromatic hydrocarbon. 15. A method for manufacturing a wafer according to any one of items 12 to 14, wherein the content of the silylating agent in the surface treatment composition is 0.3 mass% or more and 30 mass% or less based on 100 mass% of the surface treatment composition. 16. A method for manufacturing a wafer according to item 12 to 15. 17. A method for manufacturing a wafer according to any one of 12. to 16., wherein in the surface treatment composition, the boiling point difference between the boiling point of the solvent and the boiling point of the silylating agent at 1 atmosphere (boiling point of solvent - boiling point of silylating agent) is 20°C or more. 18. A method for manufacturing a wafer according to any one of 12. to 16., wherein in the surface treatment composition, the silicon compound comprises one or more selected from the group consisting of trimethylsilyldimethylamine, trimethylsilyldiethylamine, N-(trimethylsilyl)-tert-butylamine, and hexamethyldisilazane, and compounds in which at least one trimethylsilyl group of these trimethylsilylamines is substituted with any one of an ethyldimethylsilyl group, a propyldimethylsilyl group, a butyldimethylsilyl group, a hexyldimethylsilyl group, an octyldimethylsilyl group, and a decyldimethylsilyl group. 1. A method for manufacturing a wafer according to any one of the above, wherein the surface treatment composition does not contain an acyclic carbonate ester or contains an acyclic carbonate ester in an amount of 2 mass % or less relative to 100 mass % of the surface treatment composition.19. The method for manufacturing a wafer according to any one of 12. to 18., wherein the surface treatment composition does not contain a catalyst or contains a catalyst in an amount of 2 mass% or less relative to 100 mass% of the surface treatment composition. 20. The method for manufacturing a wafer according to any one of 12. to 19., wherein the number of particles larger than 0.2 μm in the surface treatment composition, as measured using a light scattering liquid-borne particle detector, is 1.0 x 10 per mL of the surface treatment composition. ４ 21. A method for manufacturing a wafer according to any one of 12. to 20., wherein the total content of Na, Mg, Ca, Mn, Fe, Cu, Li, Al, Cr, Ni, Zn, and Ag in the surface treatment composition, as measured by inductively coupled plasma mass spectrometry, is 100 ppb by mass or less. 22. A method for manufacturing a wafer according to any one of 12. to 21., wherein vapor of the surface treatment composition is supplied while iPA is held on the surface of the wafer. 23. A method for manufacturing a wafer according to any one of 12. to 22., comprising a step of mixing materials for each component of the surface treatment composition, wherein the total amount of moisture in the materials is 2000 ppm by mass or less with respect to the total amount of the materials.

[0010] According to the present invention, there are provided a surface treatment composition that easily increases the water contact angle, and a method for producing a wafer using the same.

[0011] Fig. 2 is a schematic perspective view of a wafer having a fine uneven pattern on its surface. Fig. 3 is a schematic cross-sectional view showing a part of the aa' cross section in Fig. 1. Fig. 4 is a schematic cross-sectional view of a state in which vapor of a composition is supplied to a recessed portion holding a liquid. Fig. 5 is a schematic cross-sectional view of a wafer on which a water-repellent protective film is formed.

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are designated by similar reference numerals, and descriptions thereof will be omitted where appropriate. Furthermore, the drawings are schematic diagrams and do not correspond to actual dimensional proportions.

[0013] The surface treatment composition of this embodiment will be outlined below.

[0014] The surface treatment composition of this embodiment is supplied as a vapor to the surface of a wafer having a concave-convex pattern on its surface, and is used to form a water-repellent protective film on the surface. This surface treatment composition contains a silylating agent and a solvent, the silylating agent containing a silicon compound represented by the following formula (1), and the solvent containing 75 mass % or more of a hydrocarbon solvent relative to 100 mass % of the total amount of solvent. (R １ ) ３ Si-X (1) (where R １ are each independently a group selected from the group consisting of a hydrocarbon group having 1 to 10 carbon atoms and a hydrocarbon group having 1 to 10 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms, and X is an amino group.

[0015] By using the surface treatment composition of this embodiment and applying it to the production of a wafer having a concave-convex pattern on its surface, it is possible to prevent the concave-convex pattern from collapsing.

[0016] Here, the manufacturing of semiconductor wafers will be described as an example. In the manufacturing process of semiconductor wafers, a fine uneven pattern is formed on the surface of a substrate (wafer) through film formation, lithography, etching, and the like. Then, to clean the wafer surface, a wet process such as a cleaning process using water or an organic solvent is performed. A drying process is also performed to remove liquids such as cleaning solutions and rinse solutions that have adhered to the wafer during the wet process. It is known that during this drying process, wafers having a fine uneven pattern are prone to deformation and collapse of the uneven pattern. By forming a water-repellent protective film on the uneven pattern using vapor from a surface treatment composition and modifying the wafer surface so that it exhibits water repellency, it is possible to suppress deformation and collapse of the uneven pattern during the drying process. This allows for a wafer manufacturing method with excellent manufacturing stability.

[0017] According to the findings of the present inventors, it has been found that the water contact angle of the surface treatment composition can be easily increased by including the specified silicon compound as a silylating agent and using a hydrocarbon solvent whose content in the solvent is 97% by mass or more as a solvent. Furthermore, it has been found that a practically high contact angle can be maintained even by using a hydrocarbon solvent whose content in the solvent is increased to 75% by mass or more. From the viewpoint of improving the throughput of the manufacturing process, it is preferable to use a method that can easily increase the water contact angle even in a shorter time.

[0018] Although the detailed mechanism is unclear, by using a hydrocarbon solvent that is less likely to react with the specific silicon compound of the silylating agent as the main component of the solvent, it is possible to suppress the reaction in liquid, improve storage stability, and also suppress the reaction in gas (vapor), which is thought to make the surface treatment composition more likely to increase the water contact angle. Furthermore, the solvent with a high boiling point (low volatility) preferentially aggregates on the wafer surface and is replaced with the cleaning solution, which prevents the silylating agent from reacting with the cleaning solution and being consumed, which is thought to make it easier to increase the water contact angle.

[0019] The configuration of the surface treatment composition of this embodiment will be described in detail below.

[0020] (Silylating Agent) The surface treatment composition contains one or more silicon compounds of the following formula (1) as a silylating agent (hereinafter, the silicon compound represented by formula (1) may be simply referred to as a silicon compound). However, although the silylating agent may contain only the silicon compound of the following formula (1), it may also contain a silylating agent other than the silicon compound of the following formula (1) as long as the effects of the present invention are not impaired.

[0021] (R １ ) ３ Si-X (1) (where R １ are each independently a group selected from the group consisting of a hydrocarbon group having 1 to 10 carbon atoms and a hydrocarbon group having 1 to 10 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms, and X is an amino group.

[0022] The amino group may be a monovalent group obtained by removing hydrogen from ammonia, a primary amine, or a secondary amine, and may be, for example, —NH ２ , a dialkylamino group (-N(CH ３ ) ２ , -N(C ２ H ５ ) ２ etc.), t-butylamino group, allylamino group, —NHSi(CH ３ ) ３ , -NH-C(=O)-Si(CH ３ ) ３ , -NHC(=O)CH ３ , -NHC(=O)CF ３ , -N(CH ３ )C(=O)CH ３ , -N(CH ３ )C(=O)CF ３ , -NHC(=O)-OSi(CH ３ ) ３ , -NHC(=O)-NH-Si(CH ３ ) ３ (for example, N,N'-bis(trimethylsilyl)urea, etc.), a group having a nitrogen-containing ring (wherein the nitrogen atom constituting the ring is bonded to the aforementioned Si atom), etc. may also be used. Examples of the nitrogen-containing ring include a piperidine ring, an imidazole ring (for example, N-trimethylsilylimidazole, etc.), a triazole ring (for example, N-trimethylsilyltriazole, etc.), a tetrazole ring, an oxazolidinone ring, a morpholine ring, and other nitrogen-containing heterocycles. From the viewpoint of further increasing the water contact angle, the amino group is preferably a dialkylamino group, more preferably a dialkylamino group having 1 to 4 carbon atoms in the alkyl group, and more preferably a dimethylamino group (-N(CH ３ ) ２ It is more preferable that R １ From the viewpoint of further increasing the water contact angle, each of R preferably independently contains a hydrocarbon group having 1 to 10 carbon atoms, more preferably contains a hydrocarbon group having 1 to 6 carbon atoms, and further preferably contains a hydrocarbon group having 1 to 4 carbon atoms. １Preferably, contains a hydrocarbon group having 3 to 4 carbon atoms, more preferably a propyl group or a butyl group.

[0023] The silicon compound has one Si atom in one molecule and the above-mentioned R １and one amino group bonded thereto. Specific examples include trimethylsilylamines such as trimethylsilyldimethylamine, trimethylsilyldiethylamine, N-(trimethylsilyl)-tertiarybutylamine, hexamethyldisilazane, trimethylsilylpiperidine, and N-(trimethylsilyl)-imidazole, as well as compounds in which at least one trimethylsilyl group in the above trimethylsilylamines has been substituted with an ethyldimethylsilyl group, a propyldimethylsilyl group, a butyldimethylsilyl group, a hexyldimethylsilyl group, an octyldimethylsilyl group, or a decyldimethylsilyl group (specifically, ethyldimethylsilyldimethylamine, propyldimethylsilyldimethylamine, butyldimethylsilyldimethylamine, hexyldimethylsilyldimethylamine, octyldimethylsilyldimethylamine, and decyldimethylsilyldimethylamine). These compounds may be used alone or in combination of two or more. Among these, from the viewpoint of resistance to deactivation of the silylating agent upon vaporization (steam stability), at least one selected from the group consisting of trimethylsilyldimethylamine, trimethylsilyldiethylamine, N-(trimethylsilyl)-tert-butylamine, hexamethyldisilazane, and the trimethylsilylamines (trimethylsilyldimethylamine, trimethylsilyldiethylamine, N-(trimethylsilyl)-tert-butylamine, and hexamethyldisilazane) in which at least one trimethylsilyl group is an ethyldimethylsilyl group, a propyldimethylsilyl group, a butyldimethylsilyl group, a hexyldimethylsilyl group, an octyldimethylsilyl group, and a decyldimethylsilyl group (specifically, ethyldimethylsilyldimethylamine, propyldimethylsilyldimethylamine, butyldimethylsilyldimethylamine, hexyldimethylsilyldimethylamine, octyldimethylsilyldimethylamine, decyldimethylsilyldimethylamine, etc.) is preferred.From the viewpoint of silylation reactivity, at least one selected from the group consisting of trimethylsilyldimethylamine, trimethylsilyldiethylamine, and N-(trimethylsilyl)-tertiarybutylamine is more preferable. From the viewpoint of further increasing the water contact angle, at least one selected from the group consisting of trimethylsilyldimethylamine, propyldimethylsilyldimethylamine, and butyldimethylsilyldimethylamine is more preferable.

[0024] The lower limit of the content of the silylating agent is, for example, 0.3% by mass or more, preferably 1% by mass or more, and more preferably 2% by mass or more, based on 100% by mass of the surface treatment composition. This makes it easy for the surface treatment composition to increase the water contact angle. On the other hand, the upper limit of the content of the silylating agent is, for example, 30% by mass or less, preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, based on 100% by mass of the surface treatment composition. This improves storage stability.

[0025] The lower limit of the content of the silicon compound is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, based on 100% by mass of the silylating agent. This makes it easy for the surface treatment composition to increase the water contact angle. On the other hand, the upper limit of the content of the silicon compound is not particularly limited, based on 100% by mass of the silylating agent, but may be 100% by mass or less, or 98% by mass or less when multiple silylating agents are used in combination.

[0026] (Solvent) The surface treatment composition contains one or more hydrocarbon solvents as the solvent.

[0027] Examples of the hydrocarbon solvent include hydrocarbons having 5 to 24 carbon atoms that are liquid at 1 atmosphere, and may be hydrocarbons having not only a linear structure but also a branched structure or a cyclic structure. Furthermore, the hydrocarbons contained therein may have a double bond, and some of the hydrogen atoms may be substituted with halogen atoms.

[0028] Specific examples of hydrocarbon solvents include linear saturated aliphatic hydrocarbons such as n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-hexadecane, n-octadecane, and n-eicosane, as well as branched saturated aliphatic hydrocarbons corresponding to the number of carbon atoms therein; alicyclic hydrocarbons such as cyclohexane, methylcyclohexane, ethylcyclohexane, propylcyclohexane, isopropylcyclohexane, butylcyclohexane, amylcyclohexane, 1,1,3-trimethylcyclohexane, 1,1,4-trimethylcyclohexane, 1,2,3-trimethylcyclohexane, 1,2,4-trimethylcyclohexane, 1,3,5-trimethylcyclohexane, and decalin; cyclic hydrocarbons such as o-, m-, or p-), diphenylmenthane, limonene, terpinene (α-, β-, or γ-), bornane, norbornane, pinane, pinene (α- or β-), carane, and longifolene; aromatic hydrocarbons such as benzene, allylbenzene, toluene, styrene, xylene (o-, m-, or p-), ethylbenzene, 1,2-diethylbenzene, 1,3-diethylbenzene, 1,4-diethylbenzene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, n-butylbenzene, isobutylbenzene, and tert-butylbenzene; and halogenated hydrocarbons such as 1,3-bis(trifluoromethyl)benzene and 1,4-bis(trifluoromethyl)benzene. These may be used alone or in combination of two or more.Among these, from the viewpoint of ease in increasing the water contact angle, the hydrocarbon solvent is preferably at least one selected from the group consisting of 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, tert-butylbenzene, ethylbenzene, 1,3-bis(trifluoromethyl)benzene, 1,4-bis(trifluoromethyl)benzene, p-xylene, n-nonane, and isododecane, and more preferably at least one selected from the group consisting of 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, tert-butylbenzene, ethylbenzene, 1,3-bis(trifluoromethyl)benzene, 1,4-bis(trifluoromethyl)benzene, and p-xylene.

[0029] The ease of increasing the water contact angle was evaluated by measuring the water contact angle at five points on a sample obtained by puddling iPA on the surface of a smooth silicon wafer with a thermal oxide film, supplying vapor of the surface treatment composition to the puddle for 40 seconds under predetermined conditions, washing with iPA, and drying, as described later in the Examples.

[0030] Furthermore, from the viewpoint of easily suppressing the variation in the water contact angle, the hydrocarbon solvent preferably contains an aromatic hydrocarbon. Among aromatic hydrocarbons, it is more preferable to contain at least one selected from the group consisting of 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, tert-butylbenzene, ethylbenzene, 1,3-bis(trifluoromethyl)benzene, 1,4-bis(trifluoromethyl)benzene, and p-xylene. The variation in the water contact angle was evaluated using the standard deviation calculated from the measurement results of the water contact angle at five points on the above-mentioned sample.

[0031] The solvent contains hydrocarbon solvent in an amount of 75% by mass or more, preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 97% by mass or more, and even more preferably 99% by mass or more, based on a total solvent amount of 100% by mass. This makes it easier for the surface treatment composition to increase the water contact angle. By setting the content of hydrocarbon solvent in the solvent to 97% by mass or more and using the above-mentioned preferred types of hydrocarbon solvent in combination, it is possible to achieve a higher water contact angle while suppressing variation in the water contact angle. The solvent may also consist essentially of hydrocarbon solvent alone. The content of hydrocarbon solvent may be 100% by mass. In this case, it is acceptable for other solvents to be present to an undetectable extent.

[0032] The solvent may contain other solvents besides the hydrocarbon solvents described above, provided that the amount of the other solvents is 25% by mass or less, preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, even more preferably 5% by mass or less, even more preferably 3% by mass or less, and even more preferably 1% by mass or less, based on 100% by mass of the total amount of the solvents. The other solvents are preferably aprotic solvents, such as esters, ketones, halogen-containing solvents (excluding halogenated hydrocarbons in which at least a portion of the hydrogen atoms of the hydrocarbon solvents have been substituted with halogen atoms such as fluorine atoms), and derivatives of polyhydric alcohols having no OH groups. Propylene glycol monoethyl ether acetate (PGMEA) is preferably used.

[0033] (Surface Treatment Composition) In one example of this embodiment, the total content of the silicon compound and hydrocarbon solvent is, for example, 60 mass% or more, preferably 80 mass% or more, and more preferably 95 mass% or more, based on 100 mass% of the surface treatment composition. This makes it easier to increase the water contact angle. Furthermore, the surface treatment composition may consist only of a silylating agent and a hydrocarbon solvent, and preferably consists only of the silicon compound and a hydrocarbon solvent.

[0034] Furthermore, the surface treatment composition has a boiling point difference (boiling point of solvent - boiling point of silylating agent) between the boiling point of the solvent and the boiling point of the silylating agent at 1 atmosphere pressure of, for example, 10°C or higher, preferably 20°C or higher, more preferably 30°C or higher, even more preferably 40°C or higher, even more preferably 50°C or higher, and even more preferably 55°C or higher. This allows the solvent with a higher boiling point to preferentially aggregate on the wafer surface and be replaced with the cleaning solution, thereby preventing the silylating agent from being deactivated by contact with the cleaning solution. As a result, the surface treatment composition is likely to increase the water contact angle. The boiling point of the solvent may be such that the silylating agent does not thermally decompose during vaporization, and the boiling point difference is not particularly limited. For example, the boiling point difference may be 200°C or lower, 180°C or lower, 150°C or lower, 130°C or lower, or 110°C or lower. The boiling point of a solvent and a silylating agent containing multiple components is the boiling point of the component with the highest content (mass %) among the components contained in the solvent and the silylating agent (however, if there are two or more components with the highest content, the boiling point of the component with the highest temperature is used).

[0035] The surface treatment composition preferably contains a small amount of water, and particularly preferably contains substantially no water.

[0036] The surface treatment composition of this embodiment may contain other components in addition to the components described above, provided that the purpose of the present invention is not impaired. Examples of such other components include silylating agents other than the silicon compounds described above, solvents other than hydrocarbon solvents, surfactants, and antioxidants such as BHT (dibutylhydroxytoluene).

[0037] The surface treatment composition may be configured so that the surface treatment composition does not contain acyclic carbonate ester or contains acyclic carbonate ester in an amount of 2 mass% or less per 100 mass% of the surface treatment composition. By setting the content within the above range, storage stability can be improved. Alternatively, the surface treatment composition may be configured so that the surface treatment composition is substantially free of acyclic carbonate ester. Note that "substantially free" means that the content of the acyclic carbonate ester is to an extent that does not affect the performance of the surface treatment composition, and may be, for example, 1 mass% or less of the surface treatment composition.

[0038] The surface treatment composition may be configured to contain no catalyst or to contain a catalyst in an amount of 2 mass % or less relative to 100 mass % of the surface treatment composition. The catalyst promotes the reaction between the wafer surface and the silylating agent (the silicon compound described above). Furthermore, for the purpose of further improving storage stability, the surface treatment composition may be substantially free of a catalyst. Note that "substantially free" means that the catalyst does not affect the performance of the surface treatment composition, and may be present in an amount of, for example, 1 mass % or less in the surface treatment composition.

[0039] Examples of the catalyst include trimethylsilyl trifluoroacetate, trimethylsilyl trifluoromethanesulfonate, dimethylsilyl trifluoroacetate, dimethylsilyl trifluoromethanesulfonate, butyldimethylsilyl trifluoroacetate, butyldimethylsilyl trifluoromethanesulfonate, hexyldimethylsilyl trifluoroacetate, hexyldimethylsilyl trifluoromethanesulfonate, octyldimethylsilyl trifluoroacetate, octyldimethylsilyl trifluoromethanesulfonate, decyldimethylsilyl trifluoroacetate, decyldimethylsilyl trifluoromethanesulfonate, sulfonic acid, anhydrides of the sulfonic acid, salts of the sulfonic acid, sulfonic acid derivatives, sulfonic acid esters, sulfonimides, sulfonimide derivatives, sulfonmethides, sulfonmethide derivatives, acid imides, nitrogen-containing heterocyclic compounds, and silylated heterocyclic compounds.

[0040] The surface treatment composition of this embodiment is obtained by mixing the above-mentioned components. The obtained mixture may be purified using an adsorbent, a filter, or the like, as necessary. Alternatively, each component may be purified in advance by distillation, or may be purified using an adsorbent, a filter, or the like.

[0041] The surface treatment composition is configured so that the water contact angle of the silicon wafer surface after surface treatment, measured by the following procedure, is, for example, greater than 80°, preferably 81° or greater, more preferably 83° or greater, even more preferably 85° or greater, even more preferably 87° or greater, and even more preferably 89° or greater. It can be said that the larger the water contact angle, the more easily the surface treatment composition increases the water contact angle. (Procedure) A silicon wafer having a thermal oxide film layer on its surface is immersed in 1% by mass hydrofluoric acid at 25°C for 10 minutes, then immersed in pure water at 25°C for 1 minute, and then immersed in 2-propanol (iPA) at 25°C for 1 minute to be cleaned. The cleaned silicon wafer is placed horizontally with a puddle of iPA, and vapor of the surface treatment composition is supplied to the silicon wafer. Next, the vapor is converted to liquid on the surface of the silicon wafer, replacing the iPA retained on the surface with the liquid. Next, the silicon wafer is immersed in iPA at 25°C for 1 minute. Thereafter, air is blown onto the silicon wafer to remove the iPA from the surface. The water contact angle is measured on the silicon wafer surface obtained by the above process using 2 μl of pure water in accordance with JIS R 3257:1999 "Test method for wettability of substrate glass surfaces." Measurements are performed at five points on the silicon wafer sample, and the average value is used as the "water contact angle." The standard deviation calculated from the water contact angle measurement results at the five points is used as the "variation in water contact angle."

[0042] The surface treatment composition has a particle count of 1.0×10 per mL of the surface treatment composition, for example, 1.0×10, as measured using a light scattering liquid-borne particle detector. ４ 1.0 × 10 or less, preferably 1.0 × 10 ３ or less, more preferably 1.0 × 10 ２The particle size is configured so that the number of particles is no more than 1000. This prevents contamination of the vapor treatment device, the vaporization chamber that vaporizes the surface treatment composition, and other liquid delivery sections, which can lead to reduced device yield and reliability. While the number of particles larger than 0.2 μm is preferably as low as possible, it may be one or more per mL of the composition as long as it is within the above content range. Particle measurement in the liquid phase of the surface treatment composition is performed using a commercially available measuring device that employs a light-scattering liquid particle measurement method using a laser as a light source. The particle size refers to the light-scattering equivalent diameter based on a PSL (polystyrene latex) standard particle. Particles include particles such as dust, dirt, organic solids, and inorganic solids contained as impurities in the materials of each component of the surface treatment composition, as well as particles such as dust, dirt, organic solids, and inorganic solids introduced as contaminants during the preparation of the composition. These particles ultimately remain undissolved in the composition.

[0043] The surface treatment composition is configured so that the total content of Na, Mg, Ca, Mn, Fe, Cu, Li, Al, Cr, Ni, Zn, and Ag in the surface treatment composition, as measured by inductively coupled plasma mass spectrometry, is, for example, 100 mass ppb or less, preferably 10 mass ppb or less, and more preferably 1 mass ppb or less. This can prevent contamination of the vapor treatment apparatus, resulting in reduced device yield and reliability. On the other hand, as long as the total content is within the above range, the content of each element may be 0.0001 mass ppb or more relative to the total amount of the composition.

[0044] A method for producing a wafer using the surface treatment composition will be described below.

[0045] The wafer manufacturing method of this embodiment includes the steps of preparing a wafer having a concave-convex pattern on its surface, supplying a cleaning liquid to the surface of the wafer to clean it, and supplying vapor of the surface treatment composition to the surface holding the cleaning liquid, changing the vapor to a liquid state on the surface, replacing the cleaning liquid with the liquid, and forming a water-repellent protective film on at least a portion of the surface. In addition to the above steps, one or more of a pre-rinse (first rinse) step, a post-rinse (second rinse) step, a drying step, and a water-repellent protective film removal step may be performed. The surface treatment composition used in the wafer manufacturing method of this embodiment may be the same as the surface treatment composition described above.

[0046] 1 to 4 show an example of a process for manufacturing a wafer using a surface treatment composition. FIG. 1 is a schematic perspective view of a wafer 1 having a surface with a fine uneven pattern 2. FIG. 2 is a schematic cross-sectional view of the wafer 1 showing a portion of the aa' cross section in FIG. 1. FIG. 3 is a diagram showing a step of supplying vapor 9 of the composition to a recess 4 holding a liquid 8. FIG. 4 is a diagram showing a step of cleaning, with a liquid 10, the recess 4 on which a water-repellent protective film 11 has been formed using the composition.

[0047] First, a wafer 1 having a concave-convex pattern on its surface is prepared.

[0048] In the preparation process of the wafer 1, the following method may be used, which is one example of a method for forming a concave-convex pattern 2 on the wafer surface. First, a resist is applied to the wafer surface, and then the resist is exposed through a resist mask. Either the exposed or unexposed resist is removed to produce a resist having the desired concave-convex pattern. Alternatively, a resist having a concave-convex pattern can be obtained by pressing a mold having a pattern against the resist. Next, the wafer is etched. At this time, the substrate surface corresponding to the concave portions of the resist pattern is selectively etched. Finally, the resist is peeled off to obtain a wafer 1 having a concave-convex pattern 2 on its surface.

[0049] There are no particular limitations on the wafer on which the concave-convex pattern 2 is formed and the material of the concave-convex pattern 2. As the material of the wafer 1, various wafers can be used, such as a silicon wafer, a silicon carbide wafer, a wafer composed of multiple components including silicon element, a sapphire wafer, and various compound semiconductor wafers.

[0050] The material of the concave-convex pattern 2 may include one or more selected from the group consisting of Si, Ti, Ge, W, and Ru, as well as oxides, nitrides, nitrogen oxides, carbonitrides, and carbonoxides containing at least one of these. For example, the material of the concave-convex pattern 2 may include silicon-based materials such as silicon oxide, silicon nitride, polycrystalline silicon, single-crystalline silicon, and silicon germanium, metal-based materials such as titanium nitride, tungsten, ruthenium, tantalum nitride, and tin, combinations of these materials, and resist (photoresist) materials.

[0051] The concave-convex pattern 2 may be formed of a three-dimensional structure having, for example, one or more structures arranged along the vertical direction of the surface and / or one or more structures arranged along a horizontal direction perpendicular to the vertical direction. Examples of such a three-dimensional structure may constitute at least a part of a logic device or a memory device, such as a FinFET, a nanowire FET, a nanosheet FET, or other multi-gate FET, a three-dimensional memory cell, etc.

[0052] FIG. 2 is a cross-sectional view showing an example of a concave-convex pattern 2. In this embodiment, the pattern dimension of the concave-convex pattern 2 can be defined as at least one width dimension in the in-plane direction of the surface and / or at least one height dimension in the direction perpendicular to the surface. In the cross-sectional structure (in the substrate thickness direction) of the concave-convex pattern 2, at least one of the pattern dimensions of its width and height, or in the three-dimensional structure (three-dimensional coordinates of X, Y, and Z) of the concave-convex pattern 2, at least one of the pattern dimensions of its width (length in the X-axis direction), height (length in the Y-axis direction), and depth (length in the Z-axis direction) may be, for example, 30 nm or less, 20 nm or less, or 10 nm or less. This may also be the spacing between patterns. The surface treatment composition of this embodiment can be applied even when a wafer 1 having such a fine concave-convex pattern 2 is used.

[0053] Such a surface treatment composition is suitable for use in surface treatment of a wafer 1 having a concave-convex pattern 2 with a pattern dimension of 30 nm or less, preferably 20 nm or less.

[0054] The aspect ratio of the protrusions 3 may be, for example, 3 or more, 5 or more, or 10 or more. Pattern collapse can be suppressed even in a concave-convex pattern 2 having protrusions 3 with a fragile structure. On the other hand, the aspect ratio of the protrusions 3 is not particularly limited, but may be 100 or less. The aspect ratio of the protrusions 3 is expressed as the value obtained by dividing the height 6 of the protrusion by the width 7 of the protrusion.

[0055] The width 5 of the recess may be, for example, 70 nm or less, preferably 45 nm or less The width 5 of the recess is represented by the distance between adjacent protrusions 3 in the cross-sectional view of FIG.

[0056] Next, the surface of the wafer 1 is cleaned with a cleaning liquid. In the cleaning step, the surface of the wafer 1 may be brought into contact with an aqueous cleaning solution, which is one of the cleaning liquids. Examples of aqueous cleaning solutions include water, alcohol, an ammonium hydroxide aqueous solution, a tetramethylammonium aqueous solution, a hydrofluoric acid aqueous solution, a hydrochloric acid aqueous solution, a hydrogen peroxide aqueous solution, a sulfuric acid aqueous solution, and an organic solvent. These may be used alone or in combination of two or more.

[0057] The cleaning step may be performed once or twice or more times before the surface treatment step or the first rinse step described below. Other steps may be included between multiple cleaning steps or between a cleaning step and a surface treatment step.

[0058] Subsequently, if necessary, the surface of the wafer 1 may be brought into contact with a first rinse solution, which is one of cleaning solutions (first rinse step).

[0059] The first rinse solution may be a cleaning liquid different from the aqueous cleaning solution, such as water, an organic solvent, a mixture thereof, or a mixture of these with at least one of an acid, an alkali, a surfactant, and an oxidizing agent. Examples of organic solvents used in the first rinse solution include hydrocarbons, esters, ethers, ketones, halogen-containing solvents, sulfoxide-based solvents, alcohols, polyhydric alcohol derivatives, and nitrogen-containing solvents. Among these, it is preferable to use at least one organic solvent selected from alcohols having 3 or less carbon atoms, such as methanol, 1-propanol, and 2-propanol (isopropanol).

[0060] Alternatively, multiple types of first rinse solutions may be used. For example, rinsing may be performed in the order of an acidic or alkaline aqueous solution, followed by an organic solvent. Alternatively, an additional aqueous cleaning solution may be added, followed by rinsing in the order of an acidic or alkaline aqueous solution, the aqueous cleaning solution, and the organic solvent.

[0061] The first rinsing step may be performed once or twice or more times after the cleaning step or before the surface treatment step. Other steps may be included between multiple first rinsing steps or between the first rinsing step and the surface treatment step.

[0062] The cleaning liquid can be supplied by any known means, including, for example, a single wafer system, such as a cleaning method using a spin cleaning device in which a wafer is held substantially horizontally and rotated while a cleaning liquid is supplied near the center of rotation to clean the wafer one by one, and a batch system, such as a cleaning device in which multiple wafers are immersed in a cleaning tank and cleaned. The cleaning liquid may also be supplied as vapor, as in the case of the surface treatment composition described below. This allows the cleaning liquid to be retained in at least the recesses 4 of the concave-convex pattern 2 of the wafer 1.

[0063] Next, while a cleaning liquid (liquid 8) is held in at least the recesses 4 of the recessed / convex pattern 2, vapor 9 of the surface treatment composition of this embodiment is supplied to the surface of the recessed / convex pattern, causing the vapor 9 to change state to liquid 10 on the wafer surface, and replacing and holding the liquid 8 held in at least the recesses 4 with liquid 10, thereby forming a water-repellent protective film (protective film 11) on at least a portion of the wafer surface, for example, on the surface of the recesses 4.

[0064] When the vapor 9 of the surface treatment composition is supplied, the cleaning liquid (liquid 8) retained on the wafer surface may be the aqueous cleaning solution or the first rinse solution. From the viewpoint of manufacturing stability, the first rinse solution is preferred, and among these, 2-propanol (iPA) may be contained. That is, in one embodiment of the wafer manufacturing method, the vapor 9 of the surface treatment composition may be supplied in a state in which iPA is retained on the wafer surface.

[0065] The wafer manufacturing method may also include a step of mixing the components of the surface treatment composition, and the total amount of moisture in the materials may be, for example, 2000 ppm by mass or less, preferably 500 ppm by mass or less, more preferably 100 ppm by mass or less, and even more preferably 50 ppm by mass or less, relative to the total amount of the materials. The smaller the total amount of moisture in the materials, the more likely it is to obtain a surface treatment composition that easily increases the water contact angle, which is preferable.

[0066] Examples of a method for supplying the vapor 9 of the surface treatment composition include placing the wafer 1, with the liquid 8 held in at least the recesses 4 of the concave-convex pattern 2, in a chamber, and separately evaporating the surface treatment composition to obtain a vapor, which is then supplied to the surface of the concave-convex pattern via a pipe or a nozzle. A carrier gas such as nitrogen gas or dry air may be used for supplying the vapor.

[0067] However, the method for vaporizing the surface treatment composition is not particularly limited to the above-mentioned method, and examples thereof include a batch-type vaporization method in which a predetermined amount of the surface treatment composition in a liquid state is introduced into a vaporization chamber, and heated sufficiently to evaporate the entire amount of the surface treatment composition, and after the entire amount has evaporated, the vapor 9 is sent to a pipe or a nozzle to be supplied to the uneven pattern surface.

[0068] Another example is a continuous vaporization method in which droplets of the surface treatment composition are dropped onto a preheated small-scale vaporization section (for example, by providing a heating means in a part of a pipe), and the entire amount of the surface treatment composition is evaporated each time a drop is dropped, and the vapor 9 is sent to a pipe or a nozzle to be supplied to the uneven pattern surface.

[0069] The vaporization temperature is preferably kept at a temperature that does not pose a risk of thermal decomposition of the silylating agent, which is a protective film-forming component. A preferred vapor treatment condition is to introduce nitrogen gas and supply the mixed gas of the vapor and nitrogen gas obtained as described above to the concave-convex pattern surface after the composition of the mixed gas becomes constant. The ambient temperature near the substrate during treatment, i.e., the temperature of the vapor, is preferably lower than the boiling point of the liquid 8 held in the recesses 4. Meeting this requirement prevents the liquid 8 held in the recesses from volatilizing before being replaced with the surface treatment composition, thereby making it easier to suppress pattern collapse of the concave-convex pattern 2.

[0070] Fig. 3 is a schematic diagram showing a state in which steam 9 is supplied to a recess 4 holding a liquid 8. Fig. 4 is a schematic diagram showing a state in which a water-repellent protective film 11 has been formed on the recess 4 using a surface treatment composition. The wafer 1 in the schematic diagrams of Fig. 3 and Fig. 4 shows a part of the aa' cross section in Fig. 1.

[0071] 3 and 4, the supplied vapor 9 changes state to liquid 10 in the recess 4, and the liquid 8 held in the recess 4 is replaced by the liquid 10, so that the liquid 10 is held in the recess 4. Furthermore, in order to promote or stabilize the above-mentioned state change, the temperatures of the wafer 1 and the recess 4 may be adjusted by lowering them or keeping them constant.

[0072] On the wafer surface, the silylation agent in the liquid 10 reacts with the wafer surface, and the moieties having the water-repellent functional groups described above are fixed to the wafer surface, thereby forming a water-repellent protective film (protective film 11).

[0073] The protective film 11 does not necessarily have to be formed continuously, and does not necessarily have to be formed uniformly, but it is more preferable that it is formed continuously and uniformly, as this can impart better water repellency.

[0074] By replacing the liquid 8 retained on the wafer surface, such as the first rinse solution or aqueous cleaning solution, with the liquid 10 liquefied from the vapor 9 of the surface treatment composition, it becomes possible to perform the surface modification treatment, i.e., the formation of the protective film 11, before the surface of the concave-convex pattern 2 on the surface of the wafer 1 becomes dry. This makes it possible to prevent the concave-convex pattern 2 from collapsing.

[0075] If necessary, the liquid 10 held on the wafer surface may be subjected to known means such as heating, decompression, or drying to promote the formation of the protective film 11 .

[0076] Subsequently, if necessary, the wafer surface on which the protective film 11 is formed may be brought into contact with a second rinse solution (second rinse step). As the second rinse solution, any of the solutions exemplified for the first rinse solution can be used.

[0077] Alternatively, a plurality of types of second rinse solutions may be used. For example, rinsing can be performed by contacting the substrate with water and an organic solvent such as isopropanol in this order.

[0078] The second rinsing step may be performed once or twice or more times after the surface treatment step. Other steps may be included between the multiple second rinsing steps or between the second rinsing step and the surface treatment step.

[0079] Subsequently, after the formation of the protective film 11, a drying step may be performed, if necessary, to dry the surface of the wafer 1. The drying step can remove any liquid present on the surface of the wafer 1. The liquid may include the liquid 10, a second rinse solution, or a mixture thereof. As a drying method, known methods such as spin drying, iPA (2-propanol) vapor drying, Marangoni drying, heat drying, hot air drying, vacuum drying, and reduced pressure drying may be used.

[0080] The drying step may be performed once or twice or more times, for example, after the surface treatment step or after the second rinsing step. The drying step and the second rinsing step may be repeated alternately.

[0081] Subsequently, the protective film 11 on the surface of the wafer 1 may be removed (removal step). Examples of removal methods include heating, UV irradiation, ozone exposure, plasma irradiation, and corona discharge. Treatment with a concentrated fluid (which may contain an acid, a base, or an oxidizing agent), such as a supercritical fluid, or steam treatment may also be performed. These methods may be used alone or in combination of two or more. These treatments may be performed under atmospheric pressure or reduced pressure.

[0082] In this manner, a wafer 1 (semiconductor substrate) is obtained using the surface treatment composition of this embodiment.

[0083] 1 to 4 are directed to a wafer pattern, but the present invention is not limited thereto. In the substrate manufacturing method of this embodiment, a resist pattern is also targeted, and by using the surface treatment composition of the present invention in the cleaning and drying steps, it is possible to suppress collapse of the resist pattern.

[0084] Although the manufacturing method has been described in which the supplying step is performed after the cleaning step, the present invention is not limited to this and may be performed after various treatments performed on the concave-convex pattern 2. In addition to the above steps, the manufacturing method of the substrate may also use one or a combination of two or more known treatments. For example, a surface treatment such as a plasma treatment may be performed after the above removal step.

[0085] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention.

[0086] EXAMPLES Hereinafter, examples will be given that more specifically disclose embodiments of the present invention, but the present invention is not limited to these examples.

[0087] Example 1 (Preparation of Surface Treatment Composition) Trimethylsilyldimethylamine [(CH ３ ) ３ Si—N(CH ３ ) ２ 5 g of tert-butylbenzene (hereinafter referred to as "TMSDMA") was mixed with 95 g of tert-butylbenzene as a solvent to obtain a surface treatment composition (hereinafter referred to as "composition"). The composition immediately after preparation was evaluated in the manner described below, and the results are shown in Table 1.

[0088] (Evaluation of the Ease of Increasing the Water Contact Angle of a Composition (Evaluation of the Contact Angle of a Water-Repellent Protective Film Formed on a Wafer Surface)) Providing a wafer surface with a concave-convex pattern and replacing the cleaning liquid retained in at least the concave portions of the concave-convex pattern with another cleaning liquid have been variously studied in other literature and are already established techniques. In the present invention, the water-repellency imparting effect when a wafer was surface-treated with vapor of a composition was evaluated.

[0089] However, in the case of a wafer having a concave-convex pattern on its surface, the contact angle of the protective film 11 (water-repellent protective film) itself formed on the concave-convex pattern surface cannot be accurately evaluated.

[0090] As described in JIS R 3257:1999 "Testing Method for Wettability of Substrate Glass Surfaces," the water droplet contact angle is evaluated by dropping a few μl of water onto the surface of a sample (substrate) and measuring the angle between the water droplet and the substrate surface. However, in the case of a wafer having a pattern, the water droplet contact angle becomes very large. This is because the Wenzel effect and Cassie effect occur, and the contact angle is affected by the surface shape (roughness) of the substrate, increasing the apparent contact angle of the water droplet.

[0091] In this example, the vapor of the composition was applied to a wafer having a smooth surface to form a protective film on the wafer surface, and the protective film was regarded as a protective film formed on the surface of a wafer having a concave-convex pattern formed on its surface, and evaluation was carried out according to the following procedure. ２ A silicon wafer with a thermal oxide film having a layer was used.

[0092] (1) Cleaning of Silicon Wafer A 2 cm square smooth silicon wafer with a thermally oxidized film (a Si wafer having a 1 μm-thick thermally oxidized film layer on its surface; manufactured by Kyodo International) was immersed in a 1 mass % aqueous solution of hydrofluoric acid at 25° C. for 10 minutes, immersed in pure water at 25° C. for 1 minute, and subsequently immersed in 2-propanol (hereinafter referred to as “iPA”) at 25° C. for 1 minute.

[0093] (2) Surface Treatment of Silicon Wafer Surface with Steam After the above cleaning, the silicon wafer was placed horizontally in a steam treatment chamber with a puddle of iPA, and the solution-state composition prepared above was vaporized under the following steam supply conditions, and the vapor was supplied to the steam treatment chamber. The vapor was then converted to a liquid state at the wafer surface at 50°C or below, and the iPA retained on the wafer surface was replaced with the liquid.

[0094] Conditions for supplying the vapor of the above composition: 2 dm of nitrogen gas was supplied to a vaporization chamber heated to 165°C. ３ The solution composition prepared above was added dropwise at a rate of 0.01 g / sec while the solution was flowing at a flow rate of 1 / min. The entire amount of the solution was vaporized. The vapor was immediately supplied to the vapor treatment chamber by nitrogen gas flow. The treatment was carried out for 40 seconds.

[0095] (3) Cleaning of Silicon Wafer The silicon wafer was then removed from the steam treatment chamber and immersed in iPA at 25°C for 1 minute. Finally, the silicon wafer was removed from the iPA and air was blown onto it to remove the iPA from the surface. This resulted in a silicon wafer with a protective film formed on its surface.

[0096] (4) Measurement of Water Contact Angle of Protective Film 2 μl of pure water was placed on the wafer surface on which the protective film was formed, and the angle between the water droplet and the wafer surface (water contact angle) was measured at five points using a contact angle meter (CA-X model, manufactured by Kyowa Interface Science Co., Ltd.) in accordance with JIS R 3257:1999 "Test method for wettability of substrate glass surfaces," and the average value and standard deviation (variation in water contact angle within the wafer surface) were calculated. Note that the contact angle on the surface of a silicon wafer on which no protective film was formed, obtained by performing the processes (1) and (3) without performing the above (2), was less than 10°.

[0097]

[0098] Examples 2 to 31, and Comparative Examples 1 and 2: Compositions were prepared in the same manner as in Example 1, except that the solvents listed in Table 1 were used, and various evaluations were performed. The results are shown in Table 1. In Table 1, the boiling point difference between the silylating agent and the solvent was calculated using known literature values ​​or catalog values, and "-" indicates that no literature value was available and therefore not calculated. Furthermore, "-" for the variation in water contact angle indicates that it was not measured. The solvent in Example 24 was a mixed solvent containing 60 mass% of 1,2,4-trimethylbenzene and 40 mass% of isododecane relative to the total amount of solvent. The solvent in Example 25 was a mixed solvent containing 60 mass% of 1,3,5-trimethylbenzene and 40 mass% of isododecane. The solvent in Example 26 was a mixed solvent containing 60 mass% of tert-butylbenzene and 40 mass% of isododecane. The solvent in Example 27 was a mixed solvent containing 98 mass% of 1,2,4-trimethylbenzene relative to the total amount of solvent. %, and 2 mass% propylene glycol monoethyl ether acetate (PGMEA). The solvent of Example 28 is a mixed solvent of 80 mass% 1,2,4-trimethylbenzene and 20 mass% PGMEA. The solvent of Example 29 is a mixed solvent of 98 mass% tert-butylbenzene and 2 mass% PGMEA. The solvent of Example 30 is a mixed solvent of 80 mass% tert-butylbenzene and 20 mass% PGMEA. Furthermore, the solvent of Comparative Example 1 is a mixed solvent in which, based on the total amount of solvent, propylene carbonate is 47 mass% and diethyl carbonate is 53 mass%. The solvent of Comparative Example 2 is a mixed solvent in which, based on the total amount of solvent, 1,2,4-trimethylbenzene is 70 mass% and PGMEA is 30 mass%. Furthermore, the silylating agent of Examples 4 and 6 was propyldimethylsilyldimethylamine [PDMSDMA:CH ３ CH ２ CH ２ ) (CH ３ ) ２ Si—N(CH ３ ) ２ ], and the silylating agent in Examples 5 and 6 was butyldimethylsilyldimethylamine [BDMSDMA:(CH ３ CH ２ CH ２ CH ２ ) (CH ３ ) ２ Si—N(CH ３) ２ 〕

[0099] The water contact angles (average values) of the surface treatment compositions of Examples 1 to 31 were larger than those of Comparative Examples 1 and 2, indicating that the surface treatment compositions of the present invention are more likely to increase the water contact angle than conventional compositions. Furthermore, among the above examples, when 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, tert-butylbenzene, ethylbenzene, 1,3-bis(trifluoromethyl)benzene, 1,4-bis(trifluoromethyl)benzene, p-xylene, n-nonane, or isododecane was used as the solvent, the water contact angle was more likely to be increased. Furthermore, among the above examples, when 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, tert-butylbenzene, ethylbenzene, 1,3-bis(trifluoromethyl)benzene, 1,4-bis(trifluoromethyl)benzene, or p-xylene was used as the solvent, a higher water contact angle was obtained, and the standard deviation of the water contact angle was also smaller than 2.0.

[0100] This application claims priority based on Japanese Patent Application No. 2022-065098 filed on April 11, 2022, and Japanese Patent Application No. 2022-128657 filed on August 12, 2022, the disclosures of which are incorporated herein in their entireties.

[0101] REFERENCE SIGNS LIST 1 wafer 2 concave-convex pattern 3 convex portion 4 concave portion 5 width of concave portion 6 height of convex portion 7 width of convex portion 8 liquid 9 vapor 10 liquid 11 protective film

Claims

1. A surface treatment composition comprising a silylation agent and a solvent, the surface treatment composition being supplied as a vapor to a surface of a wafer having a concave-convex pattern on the surface and used to form a water-repellent protective film on the surface, the surface treatment composition comprising: The silylating agent comprises a silicon compound represented by formula (1), (R １ ) ３ Si-X (1) (However, R １ are each independently a group selected from the group consisting of a hydrocarbon group having 1 to 10 carbon atoms and a hydrocarbon group having 1 to 10 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms, and X is an amino group. The solvent contains 75 mass% or more of a hydrocarbon solvent in a total amount of 100 mass% of the solvent. Surface treatment composition.

2. The surface treatment composition according to claim 1, A surface treatment composition, wherein the content of the hydrocarbon solvent is 97 mass% or more with respect to 100 mass% of a total amount of the solvent.

3. The surface treatment composition according to claim 1 or 2, The surface treatment composition, wherein the hydrocarbon solvent comprises an aromatic hydrocarbon.

4. The surface treatment composition according to claim 1 or 2, A surface treatment composition, wherein the content of the silylating agent is 0.3 mass % or more and 30 mass % or less, based on 100 mass % of the surface treatment composition.

5. The surface treatment composition according to claim 1 or 2, The surface treatment composition, wherein the boiling point difference between the boiling point of the solvent and the boiling point of the silylating agent at 1 atmospheric pressure (boiling point of the solvent-boiling point of the silylating agent) is 20° C. or more.

6. The surface treatment composition according to claim 1 or 2, The silicon compound comprises one or more selected from the group consisting of trimethylsilyldimethylamine, trimethylsilyldiethylamine, N-(trimethylsilyl)-tertiarybutylamine, hexamethyldisilazane, and compounds in which at least one trimethylsilyl group of these trimethylsilylamines is substituted with any one of an ethyldimethylsilyl group, a propyldimethylsilyl group, a butyldimethylsilyl group, a hexyldimethylsilyl group, an octyldimethylsilyl group, and a decyldimethylsilyl group.

7. The surface treatment composition according to claim 1 or 2, A surface treatment composition, wherein the water contact angle of a silicon wafer surface after the surface treatment is greater than 80°, as measured by the following procedure. (procedure) A smooth silicon wafer having a thermal oxide layer on its surface is immersed in a 1 mass % aqueous solution of hydrofluoric acid at 25° C. for 10 minutes, in pure water at 25° C. for 1 minute, and in 2-propanol (iPA) at 25° C. for 1 minute for cleaning. The silicon wafer after cleaning is placed horizontally with a puddle of iPA on it, and the vapor of the surface treatment composition is supplied to the silicon wafer. Next, the vapor is changed into a liquid state on the surface of the silicon wafer, and the iPA held on the surface is replaced with the liquid. The silicon wafer is then immersed in iPA at 25° C. for 1 minute. Thereafter, air is blown onto the silicon wafer to remove the iPA from the surface. The water contact angle is measured on the silicon wafer surface obtained by the above steps using 2 μl of pure water in accordance with JIS R 3257:1999 “Test method for wettability of substrate glass surface”.

8. The surface treatment composition according to claim 1 or 2, The surface treatment composition does not contain a non-cyclic carbonate ester, or contains a non-cyclic carbonate ester in an amount of 2 mass % or less relative to 100 mass % of the surface treatment composition.

9. The surface treatment composition according to claim 1 or 2, A surface treatment composition which does not contain a catalyst or contains a catalyst in an amount of 2 mass% or less relative to 100 mass% of the surface treatment composition.

10. The surface treatment composition according to claim 1 or 2, The number of particles larger than 0.2 μm as measured using a light scattering liquid-borne particle detector is 1.0 × 10 per mL of the surface treatment composition. ４ The surface treatment composition has a particle size of 100 or less.

11. The surface treatment composition according to claim 1 or 2, A surface treatment composition, in which the total content of Na, Mg, Ca, Mn, Fe, Cu, Li, Al, Cr, Ni, Zn and Ag in the surface treatment composition is 100 ppb by mass or less, as measured by inductively coupled plasma mass spectrometry.

12. preparing a wafer having a concave-convex pattern on its surface; applying a cleaning liquid to the surface of the wafer to clean it; supplying vapor of a surface treatment composition to the surface holding the cleaning liquid, changing the state of the vapor to a liquid on the surface, and replacing the cleaning liquid with the liquid, thereby forming a water-repellent protective film on at least a portion of the surface, the surface treatment composition comprises a silylating agent and a solvent; The silylating agent comprises a silicon compound represented by formula (1), (R １ ) ３ Si-X (1) (However, R １ are each independently a group selected from the group consisting of a hydrocarbon group having 1 to 10 carbon atoms and a hydrocarbon group having 1 to 10 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms, and X is an amino group. The solvent contains 75 mass% or more of a hydrocarbon solvent in a total amount of 100 mass% of the solvent. A method for manufacturing a wafer.

13. 13. A method for manufacturing a wafer according to claim 12, comprising the steps of: A method for producing a wafer, wherein the content of the hydrocarbon solvent is 97 mass % or more with respect to a total amount of the solvent being 100 mass %.

14. A method for producing a wafer according to claim 12 or 13, comprising the steps of:

2. The method for producing a wafer, wherein in the surface treatment composition, the hydrocarbon solvent comprises an aromatic hydrocarbon.

15. A method for producing a wafer according to claim 12 or 13, comprising the steps of: A method for producing a wafer, wherein the content of the silylating agent in the surface treatment composition is 0.3 mass % or more and 30 mass % or less based on 100 mass % of the surface treatment composition.

16. A method for producing a wafer according to claim 12 or 13, comprising the steps of: In the surface treatment composition, the boiling point difference between the boiling point of the solvent and the boiling point of the silylation agent at 1 atmospheric pressure (boiling point of the solvent-boiling point of the silylation agent) is 20° C. or more.

17. A method for producing a wafer according to claim 12 or 13, comprising the steps of: The method for producing a wafer, wherein the silicon compound in the surface treatment composition contains one or more selected from the group consisting of trimethylsilyldimethylamine, trimethylsilyldiethylamine, N-(trimethylsilyl)-tertiarybutylamine, hexamethyldisilazane, and compounds in which at least one trimethylsilyl group of these trimethylsilylamines is substituted with any one of an ethyldimethylsilyl group, a propyldimethylsilyl group, a butyldimethylsilyl group, a hexyldimethylsilyl group, an octyldimethylsilyl group, and a decyldimethylsilyl group.

18. A method for producing a wafer according to claim 12 or 13, comprising the steps of: A method for producing a wafer, wherein the surface treatment composition does not contain a non-cyclic carbonate ester or contains a non-cyclic carbonate ester in an amount of 2 mass % or less relative to 100 mass % of the surface treatment composition.

19. A method for producing a wafer according to claim 12 or 13, comprising the steps of: A method for producing a wafer, wherein the surface treatment composition does not contain a catalyst or contains a catalyst in an amount of 2 mass % or less relative to 100 mass % of the surface treatment composition.

20. A method for producing a wafer according to claim 12 or 13, comprising the steps of: In the surface treatment composition, the number of particles larger than 0.2 μm as measured using a light scattering type liquid-borne particle detector is 1.0 × 10 per mL of the surface treatment composition. ４ The method of claim 1, wherein the number of wafers is less than or equal to 100.

21. A method for producing a wafer according to claim 12 or 13, comprising the steps of: A method for manufacturing a wafer, wherein the total content of Na, Mg, Ca, Mn, Fe, Cu, Li, Al, Cr, Ni, Zn and Ag in the surface treatment composition is 100 ppb by mass or less as measured by inductively coupled plasma mass spectrometry.

22. A method for producing a wafer according to claim 12 or 13, comprising the steps of: A method for manufacturing a wafer, comprising: supplying vapor of the surface treatment composition to the surface of the wafer while the iPA is held on the surface of the wafer.

23. A method for producing a wafer according to claim 12 or 13, comprising the steps of: A method for manufacturing a wafer, comprising: mixing materials of each component of the surface treatment composition, wherein a total amount of moisture in the materials is 2000 mass ppm or less with respect to a total amount of the materials.