JP5974515B2 - Water repellent protective film forming chemical, water repellent protective film forming chemical kit, and wafer cleaning method - Google Patents

Description

  The present invention relates to a substrate wafer cleaning technique in semiconductor device manufacturing or the like.

  In the manufacture of semiconductor chips, a fine uneven pattern is formed on the surface of a silicon wafer through film formation, lithography, etching, etc., and then a cleaning liquid such as water or an organic solvent is used to clean the wafer surface. Washing is done. The elements are in the direction of miniaturization, and the interval between the concave and convex patterns is becoming narrower. For this reason, after the cleaning, when the cleaning liquid is dried from the wafer surface, a problem that the concave / convex pattern collapses due to the capillary force acting on the concave portion of the wafer is likely to occur. This problem has become more prominent particularly in semiconductor chips of the 20 nm and 10 nm generations where the uneven pattern spacing is narrower.

For this reason, if the capillary force acting on the concave portion is reduced, it can be expected that the pattern collapse is eliminated. The magnitude of the capillary force is the absolute value of P obtained by the following formula. From this formula, it is expected that the capillary force can be reduced by reducing γ or cos θ.
P = 2 × γ × cos θ / S
(Wherein γ is the surface tension of the liquid held in the recess, θ is the contact angle between the recess surface and the liquid held in the recess, and S is the width of the recess.)

  As a method for cleaning the wafer surface while preventing the pattern from collapsing, Patent Document 1 discloses a method in which water remaining on the wafer surface is replaced with isopropanol and then dried. In Patent Document 2, after cleaning the wafer surface with water, a water-repellent protective film is formed on the concavo-convex pattern portion containing silicon with a silane coupling agent, and then rinsed with water and then dried. A method is disclosed. This protective film is finally removed. Since the pattern portion is made water-repellent by the protective film when rinsing with water, the effect of suppressing the collapse of the concavo-convex pattern is produced. This method is said to be effective even for patterns having an aspect ratio of 8 or more. Furthermore, Patent Document 3 discloses a silylating agent containing at least one compound having a disilazane structure as a surface treatment agent capable of efficiently forming a water-repellent protective film, and a solvent containing a 5- or 6-membered lactone compound. It is disclosed to use a surface treatment agent containing

JP 2003-45843 A Japanese Patent No. 4403202 JP 2011-91349 A

  As described in the background art, when trying to prevent pattern collapse by making the surface of the concave / convex pattern of the wafer water repellent, the contact angle when assuming that water is retained on the surface after water repellent is larger. Since the capillary force acting on the concave portion calculated from the equation of capillary force is reduced, it is desired that water repellency superior to conventional silane coupling agents is imparted to the wafer surface. In the wafer cleaning process, it is necessary to quickly form a water-repellent protective film on the wafer surface for the water repellency. In order to quickly form a water-repellent protective film and to give better water repellency, in order to increase the reactivity between the silane coupling agent and reactive sites such as silanol groups present on the wafer surface, It is effective to use a solvent. However, particularly when a silane coupling agent containing a large number of carbon atoms in the hydrophobic group is used, it is difficult to dissolve in the solvent as described above, and the uneven pattern is caused by the presence of an insoluble component. There was a problem that there was a risk of damage. According to the present invention, an insoluble component is generated in a method of cleaning a wafer containing silicon oxide on the surface (hereinafter, sometimes simply referred to as “wafer”) using a liquid while preventing collapse of the concavo-convex pattern. A water repellent protective film forming chemical that can form a water repellent protective film (hereinafter, simply referred to as “protective film”) that imparts excellent water repellency to the uneven pattern surface (hereinafter, Simply “protective film-forming chemical solution” or “chemical solution”), a water-repellent protective film-forming chemical solution kit for obtaining the chemical solution (hereinafter sometimes simply referred to as “chemical solution kit”), It is another object of the present invention to provide a method for cleaning a wafer using a chemical solution obtained from the chemical solution or the chemical solution kit.

  In the present invention, the water-repellent protective film is a film that is formed on the wafer surface to lower the wettability of the wafer surface, that is, a film that imparts water repellency. In the present invention, the water repellency means that the surface energy of the article surface is reduced and the interaction (for example, hydrogen bond, intermolecular force) between water or other liquid and the article surface is reduced. It is. In particular, the effect of reducing the interaction with water is great, but it has the effect of reducing the interaction with a mixed liquid of water and a liquid other than water or a liquid other than water. By reducing the interaction, the contact angle of the liquid with the article surface can be increased.

  When the wafer is processed using the chemical solution of the present invention, when the liquid such as the cleaning liquid is removed from the concave portion of the concave / convex pattern of the wafer, that is, when dried, the protective film is formed at least on the concave surface. Therefore, the capillary force acting on the concave portion is reduced, and the pattern collapse hardly occurs.

In the present invention, a water repellent protective film is formed on at least the concave surface of the wafer after the cleaning step of the wafer having an uneven pattern on the surface and containing silicon oxide on at least the concave surface of the concave / convex pattern before the drying step. A chemical solution for forming a water-repellent protective film, wherein the chemical solution is a chemical solution containing a silicon compound and a non-aqueous solvent, wherein the silicon compound is represented by the following general formula [1], A mass ratio of at least one solvent (I) selected from a lactone solvent and a carbonate solvent and a solvent (II) soluble in a silicon compound other than the solvent (I) is 40:60 to 97: 3 A chemical solution for forming a water repellent protective film.
R ¹ _a SiX _4-a [1]
[In the formula [1], each R ¹ independently represents a hydrogen group, a monovalent hydrocarbon group having 1 to 18 carbon atoms in which some or all of the hydrogen elements may be replaced by halogen elements. The total number of carbon atoms contained in all the hydrocarbon groups bonded to the silicon element is at least one group selected from the group consisting of 6 or more. X is independently of each other a monovalent functional group in which the element bonded to the silicon element is nitrogen, a monovalent functional group in which the element bonded to the silicon element is oxygen, a halogen group, a nitrile group, and , —CO—NH—Si (CH ₃ ) _3, at least one group selected from the group consisting of 3; ]

The silicon compound can chemically react with the concavo-convex pattern and the silanol group on the wafer surface. As a result, the silicon element of the silicon compound is chemically reacted with the concavo-convex pattern and the silicon element on the wafer surface via a siloxane bond. Can be bonded to each other to form a water-repellent protective film, and the surface can exhibit water repellency. The hydrocarbon group represented by R ¹ in the general formula [1] is a hydrophobic group, and the hydrophobic group is large, that is, the total number of carbon atoms contained in all the hydrocarbon groups bonded to silicon element. When the protective film is formed with a thickness of 6 or more (in other words, the total number of carbon atoms contained in a number of R ¹ groups represented by R ¹ _a is 6 or more), the wafer surface has better water repellency. Can be granted.

  The solvent contained in the chemical solution is a non-aqueous solvent. When the solvent contained in the chemical solution is water, the reactive site of the silicon compound in the chemical solution (X in the general formula [1]) is hydrolyzed with water to generate a silanol group (Si-OH), Since the reactive site also reacts with this silanol group, silicon compounds are bonded to each other to form a dimer. This dimer has a low reactivity with the silanol group on the uneven pattern surface or wafer surface, and therefore cannot sufficiently impart water repellency to the uneven pattern surface or wafer surface, or to impart water repellency. There is a problem that it takes a long time. Therefore, the raw material of the chemical solution and the raw material of the chemical solution kit for obtaining the chemical solution described later preferably have a low water content.

The nonaqueous solvent contained in the chemical solution is a mass ratio of at least one solvent (I) selected from a lactone solvent and a carbonate solvent and a solvent (II) soluble in a silicon compound other than the solvent (I). 40:60 to 97: 3. The reason for using the solvent (I), in the silane coupling-ring reaction of the silicon-containing compound and the silanol group as described above, and there is a tendency to promote the silane coupling reaction. When the solvent (I) is used, the reaction promoting effect is considered to occur because the silanol group, which is a reaction point on the wafer surface, is not solvated and becomes more reactive.

  However, the solvent (I) is difficult to dissolve a silicon compound having a large hydrophobic group. Therefore, the present inventors have conducted extensive research in view of such problems, and as a result, by adding the solvent (II) to the solvent (I), a better reaction promoting effect can be obtained while improving the solubility of the silicon compound. In addition, the inventors have found that an excellent water repellency imparting effect can be obtained even when the silicon compound concentration is low, and the present invention has been achieved. Solvent (I) and solvent (II) are comprised by mass ratio 40: 60-97: 3. When the content of the solvent (I) in 100% by mass of the non-aqueous solvent contained in the chemical solution is less than 40% by mass, it is difficult to obtain the merit of the reaction promoting effect by using the solvent (I). When the content of the solvent (I) is more than 97% by mass, it is difficult to dissolve the silicon compound having a large hydrophobic group, and the undissolved silicon compound may exist. The ratio of the solvent (I) to the solvent (II) is more preferably 70:30 to 95: 5 by mass ratio. When the content of the solvent (I) in 100% by mass of the non-aqueous solvent contained in the chemical solution is 70% by mass or more, even if the concentration of the silicon compound is low, excellent water repellency is imparted by the above-described reaction promoting effect. Since an effect is acquired, it is preferable. Moreover, since the content rate of the said solvent (I) is 95 mass% or less, since a silicon compound is easy to dissolve and there is no undissolved residue, it is preferable.

  Examples of such a solvent (I) include γ-butyrolactone, γ-valerolactone, γ-hexanolactone, γ-heptanolactone, γ-octanolactone, γ-nonanolactone, γ-decanolactone, γ-undecanolactone, γ-dodecanolactone, δ-valerolactone, δ-hexanolactone, δ-octanolactone, δ-nonanolactone, δ-decanolactone, δ-undecanolactone, δ-dodecanolactone, ε-hexanolactone, etc. Examples include lactone solvents and carbonate solvents such as propylene carbonate. Of these, lactone solvents are more preferable because of their high polarity and excellent reaction promotion effect.

  In addition, since the silicon compound easily reacts with a protic solvent, and as a result, the reactivity of the silicon compound tends to decrease, the solvent (I) and the solvent (II) used as the non-aqueous solvent are: Both are preferably aprotic solvents.

Examples of the solvent (II) include hydrocarbons, esters, ethers, ketones, halogen-containing solvents, sulfoxide solvents, polyhydric alcohol derivatives having no hydroxyl group, and nitrogen element containing no NH bond. A solvent is mentioned. Examples of said hydrocarbons are toluene, benzene, xylene, hexane, heptane, include octane, examples of the esters include ethyl acetate, propyl acetate, butyl acetate, hexyl acetate, etc. acetoacetic ethyl acetate Examples of the ethers include diethyl ether, dipropyl ether, dibutyl ether, tetrahydrofuran, dioxane, and the like. Examples of the ketones include acetone, acetylacetone, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, and the like. Examples of the halogen-containing solvent include perfluorocarbons such as perfluorooctane, perfluorononane, perfluorocyclopentane, perfluorocyclohexane, hexafluorobenzene, 1, 1, 1, 3, 3-pe. Hydrofluorocarbons such as tafluorobutane, octafluorocyclopentane, 2,3-dihydrodecafluoropentane, Zeolora H (manufactured by Zeon Corporation), methyl perfluoroisobutyl ether, methyl perfluorobutyl ether, ethyl perfluorobutyl ether, ethyl Hydrofluoroethers such as perfluoroisobutyl ether, Asahiklin AE-3000 (Asahi Glass Co., Ltd.), Novec HFE-7100, Novec HFE-7200, Novec7300, and Novec7600 (all manufactured by 3M), and chlorocarbons such as tetrachloromethane , Hydrochlorocarbons such as chloroform, chlorofluorocarbons such as dichlorodifluoromethane, 1,1-dichloro-2,2,3 , 3,3-pentafluoropropane, 1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1-chloro-3,3,3-trifluoropropene, 1,2-dichloro-3 , 3,3-trifluoropropene and other hydrochlorofluorocarbons, perfluoroethers, perfluoropolyethers, etc. Examples of the sulfoxide solvents include dimethyl sulfoxide and the like, polyhydric alcohol derivatives having no hydroxyl groups Examples of diethylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, diethylene Recall dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol diacetate, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, dipropylene glycol dimethyl ether, ethylene glycol diacetate, ethylene glycol diethyl ether, ethylene glycol dimethyl ether Examples of the nitrogen element-containing solvent having no N—H bond include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, triethylamine, and pyridine.

  X in the general formula [1] is a reactive site having reactivity with a silanol group which is a reaction site of the wafer, the reactive site reacts with the silanol group of the wafer, and the silicon compound is bonded to the siloxane bond. The protective film is formed by chemically bonding to the silicon element of the wafer via When cleaning the wafer using the cleaning liquid, when the cleaning liquid is removed from the concave portion of the wafer, that is, when the wafer is dried, if the protective film is formed on the surface of the concave portion, the capillary force acting on the concave portion is reduced. Pattern collapse is less likely to occur.

The monovalent functional group in which the element bonded to the silicon element, which is an example of X in the general formula [1], is nitrogen, includes hydrogen, carbon, boron, nitrogen, phosphorus, oxygen, sulfur, silicon, germanium, fluorine, chlorine Further, elements such as bromine and iodine may be contained. Examples of the functional group include isocyanate group, amino group, alkylamino group, dialkylamino group, isothiocyanate group, azide group, acetamide group, —NHSi (CH ₃ ) ₃ group, —NHSi (CH ₃ ) ₂ C _4. H _{9 group, -NHSi (CH 3) 2 C} 8 H 17 _{group, -N (CH 3) C (} O) CH 3, -N (CH 3) C (O) CF 3, -N = C (CH 3 ) OSi (CH ₃ ) ₃ , —N═C (CF ₃ ) OSi (CH ₃ ) ₃ , —NHC (O) —OSi (CH ₃ ) ₃ , —NHC (O) —NH—Si (CH ₃ ) ₃ , Imidazole ring (formula [4]), oxazolidinone ring (formula [5]), morpholine ring (formula [6]), —NH—C (O) —Si (CH ₃ ) ₃ , —N (H ^{_{) 2-b (Si (H}} ) c R 4 3-c) b (R 4 is Part or all of the monovalent hydrocarbon group of carbon atoms, which may hydrogen elements have been replaced by fluorine element is 1 to 18, b is 1 or 2, c is an integer of 0 to 2), and the like.

In addition, the monovalent functional group in which the element bonded to the silicon element, which is an example of X in the general formula [1], is oxygen is hydrogen, carbon, boron, nitrogen, phosphorus, oxygen, sulfur, silicon, germanium, fluorine Further, elements such as chlorine, bromine and iodine may be contained. Examples of the functional group, an alkoxy _{group, -OC (CH 3) = CHCOCH} 3, -OC (CH 3) = N-Si (CH 3) 3, -OC (CF 3) = N-Si (CH 3 ) ₃ , —O—CO—R ⁵ (R ⁵ is a monovalent hydrocarbon group having 1 to 18 carbon atoms in which some or all of the hydrogen elements may be substituted with fluorine elements, etc.), some Alternatively, there is an alkyl sulfonate group in which all hydrogen elements may be substituted with fluorine element or the like.

  Examples of the halogen group as an example of X in the general formula [1] include a fluoro group, a chloro group, a bromo group, and an iodo group. Of these, a chloro group is more preferred.

Examples of the silicon compound represented by the general formula [1] include C ₄ H ₉ (CH ₃ ) ₂ SiCl, C ₅ H ₁₁ (CH ₃ ) ₂ SiCl, C ₆ H ₁₃ (CH ₃ ) ₂ SiCl, C ₇ H ₁₅ (CH ₃ ) ₂ SiCl, C ₈ H ₁₇ (CH ₃ ) ₂ SiCl, C ₉ H ₁₉ (CH ₃ ) ₂ SiCl, C ₁₀ H ₂₁ (CH ₃ ) ₂ SiCl, C ₁₁ H ₂₃ (CH ₃ ) ₂ SiCl, C ₁₂ H ₂₅ (CH ₃ ) ₂ SiCl, C ₁₃ H ₂₇ (CH ₃ ) ₂ SiCl, C ₁₄ H ₂₉ (CH ₃ ) ₂ SiCl, C ₁₅ H ₃₁ (CH ₃ ) ₂ SiCl, C _{16 H 33 (CH 3) 2} SiCl, C 17 H 35 (CH 3) 2 SiCl, C 18 H 37 (CH 3) 2 SiCl, C 5 H 11 (CH 3) HSiCl _{C 6 H 13 (CH 3)} HSiCl, C 7 H 15 (CH 3) HSiCl, C 8 H 17 (CH 3) HSiCl, C 9 H 19 (CH 3) HSiCl, C 10 H 21 (CH 3) HSiCl, _{C 11 H 23 (CH 3)} HSiCl, C 12 H 25 (CH 3) HSiCl, C 13 H 27 (CH 3) HSiCl, C 14 H 29 (CH 3) HSiCl, C 15 H 31 (CH 3) HSiCl, _{C 16 H 33 (CH 3)} HSiCl, C 17 H 35 (CH 3) HSiCl, C 18 H 37 (CH 3) HSiCl, C 2 F 5 C 2 H 4 (CH 3) 2 SiCl, C 3 F 7 C _{2 H 4 (CH 3) 2} SiCl, C 4 F 9 C 2 H 4 (CH 3) 2 SiCl, C 5 F 11 C 2 H 4 (CH 3) 2 S _{Cl, C 6 F 13 C 2} H 4 (CH 3) 2 SiCl, C 7 F 15 C 2 H 4 (CH 3) 2 SiCl, C 8 F 17 C 2 H 4 (CH 3) 2 SiCl, (C 2 H ₅ ) ₃ SiCl, C ₃ H ₇ (C ₂ H ₅ ) ₂ SiCl, C ₄ H ₉ (C ₂ H ₅ ) ₂ SiCl, C ₅ H ₁₁ (C ₂ H ₅ ) ₂ SiCl, C ₆ H ₁₃ ( C ₂ H ₅ ) ₂ SiCl, C ₇ H ₁₅ (C ₂ H ₅ ) ₂ SiCl, C ₈ H ₁₇ (C ₂ H ₅ ) ₂ SiCl, C ₉ H ₁₉ (C ₂ H ₅ ) ₂ SiCl, C ₁₀ H ₂₁ (C ₂ H ₅ ) ₂ SiCl, C ₁₁ H ₂₃ (C ₂ H ₅ ) ₂ SiCl, C ₁₂ H ₂₅ (C ₂ H ₅ ) ₂ SiCl, C ₁₃ H ₂₇ (C ₂ H ₅ ) ₂ SiCl, C ₁₄ H ₂₉ (C ₂ H ₅ ) ₂ Si Cl, C ₁₅ H ₃₁ (C ₂ H ₅ ) ₂ SiCl, C ₁₆ H ₃₃ (C ₂ H ₅ ) ₂ SiCl, C ₁₇ H ₃₅ (C ₂ H ₅ ) ₂ SiCl, C ₁₈ H ₃₇ (C ₂ H ₅ ) ₂ SiCl, (C ₄ H ₉ ) ₃ SiCl, C ₅ H ₁₁ (C ₄ H ₉ ) ₂ SiCl, C ₆ H ₁₃ (C ₄ H ₉ ) ₂ SiCl, C ₇ H ₁₅ (C ₄ H ₉ ) ₂ SiCl, C ₈ H ₁₇ (C ₄ H ₉ ) ₂ SiCl, C ₉ H ₁₉ (C ₄ H ₉ ) ₂ SiCl, C ₁₀ H ₂₁ (C ₄ H ₉ ) ₂ SiCl, C ₁₁ H ₂₃ (C ₄ H ₉ ) ₂ SiCl, C ₁₂ H ₂₅ (C ₄ H ₉ ) ₂ SiCl, C ₁₃ H ₂₇ (C ₄ H ₉ ) ₂ SiCl, C ₁₄ H ₂₉ (C ₄ H ₉ ) ₂ SiCl, C ₁₅ H ₃₁ (C ₄₎ H ₉ ) ₂ SiCl, C _{16 H 33 (C 4 H 9} ) 2 SiCl, C 17 H 35 (C 4 H 9) 2 SiCl, C 18 H 37 (C 4 H 9) 2 SiCl, CF 3 C 2 H 4 (C 4 H 9) ₂ SiCl, C ₂ F ₅ C ₂ H ₄ (C ₄ H ₉ ) ₂ SiCl, C ₃ F ₇ C ₂ H ₄ (C ₄ H ₉ ) ₂ SiCl, C ₄ F ₉ C ₂ H ₄ (C ₄ H ₉ ) ₂ SiCl, C ₅ F ₁₁ C ₂ H ₄ (C ₄ H ₉ ) ₂ SiCl, C ₆ F ₁₃ C ₂ H ₄ (C ₄ H ₉ ) ₂ SiCl, C ₇ F ₁₅ C ₂ H ₄ (C ₄ H ₉ ) ₂ SiCl, C ₈ F ₁₇ C ₂ H ₄ (C ₄ H ₉ ) ₂ SiCl, C ₅ H ₁₁ (CH ₃ ) SiCl ₂ , C ₆ H ₁₃ (CH ₃ ) SiCl ₂ , C ₇ H ₁₅ (CH ₃ ) SiCl ₂ , C ₈ H ₁₇ (CH ₃ ) SiC l ₂ , C ₉ H ₁₉ (CH ₃ ) SiCl ₂ , C ₁₀ H ₂₁ (CH ₃ ) SiCl ₂ , C ₁₁ H ₂₃ (CH ₃ ) SiCl ₂ , C ₁₂ H ₂₅ (CH ₃ ) SiCl ₂ , C ₁₃ H ₂₇ (CH ₃ ) SiCl ₂ , C ₁₄ H ₂₉ (CH ₃ ) SiCl ₂ , C ₁₅ H ₃₁ (CH ₃ ) SiCl ₂ , C ₁₆ H ₃₃ (CH ₃ ) SiCl ₂ , C ₁₇ H ₃₅ (CH ₃ ) SiCl ₂ , C ₁₈ H ₃₇ (CH ₃ ) SiCl ₂ , C ₃ F ₇ C ₂ H ₄ (CH ₃ ) SiCl ₂ , C ₄ F ₉ C ₂ H ₄ (CH ₃ ) SiCl ₂ , C ₅ F ₁₁ C ₂ H ₄ (CH ₃ ) SiCl ₂ , C ₆ F ₁₃ C ₂ H ₄ (CH ₃ ) SiCl ₂ , C ₇ F ₁₅ C ₂ H ₄ (CH ₃ ) SiCl ₂ , C ₈ F ₁₇ C ₂ H ₄ (CH _{3 ) SiCl 2, C 6 H 13} SiCl 3, C 7 H 15 SiCl 3, C 8 H 17 SiCl 3, C 9 H 19 SiCl 3, C 10 H 21 SiCl 3, C 11 H 23 SiCl 3, C 12 H 25 SiCl ₃ , C ₁₃ H ₂₇ SiCl ₃ , C ₁₄ H ₂₉ SiCl ₃ , C ₁₅ H ₃₁ SiCl ₃ , C ₁₆ H ₃₃ SiCl ₃ , C ₁₇ H ₃₅ SiCl ₃ , C ₁₈ H ₃₇ SiCl ₃ , C ₄ F ₉ C ₂ H ₄ SiCl ₃ , C ₅ F ₁₁ C ₂ H ₄ SiCl ₃ , C ₆ F ₁₃ C ₂ H ₄ SiCl ₃ , C ₇ F ₁₅ C ₂ H ₄ SiCl ₃ , C ₈ F ₁₇ C ₂ H ₄ SiCl _3, etc. Or a chloro group of the chlorosilane compound having 1 to 18 carbon atoms such as a methoxy group or an ethoxy group. Of or _{alkoxy, -OC (CH 3) = CHCOCH} 3, -OC (CH 3) = N-Si (CH 3) 3, -OC (CF 3) = N-Si (CH 3) 3, -O- CO—R ⁵ (R ⁵ is a monovalent hydrocarbon group having 1 to 18 carbon atoms in which some or all of the hydrogen elements may be substituted with fluorine elements, etc.), some or all of the hydrogen elements are Alkyl sulfonate group, isocyanate group, isothiocyanate group, azide group, acetamide group, —NHSi (CH ₃ ) ₃ group, —NHSi (CH ₃ ) ₂ C ₄ H ₉ which may be substituted with fluorine element or the like
_{Group, -NHSi (CH 3) 2 C} 8 H 17 _{group, -N (CH 3) C (} O) CH 3, -N (CH 3) C (O) CF 3, -N = C (CH 3) OSi _{(CH 3) 3, -N =} C (CF 3) OSi (CH 3) 3, -NHC (O) -OSi (CH 3) 3, -NHC (O) -NH-Si (CH 3) 3, imidazole ring, oxazolidinone ring, morpholine _{ring, -NH-C (O) -Si} (CH 3) 3, -N (H) 2-b (Si (H) c R 4 3-c) b (R 4 part Or a monovalent hydrocarbon group having 1 to 18 carbon atoms in which all hydrogen elements may be replaced by fluorine elements, b is an integer of 1 or 2, and c is an integer of 0 to 2, and a fluoro group, a bromo group, Examples include an iodo group, a nitrile group, or a compound substituted with —CO—NH—Si (CH ₃ ) ₃ . It is.

Among the above silicon compounds, when the hydrogen element of the hydrocarbon group represented by R ¹ in the general formula [1] is substituted with a halogen element, the halogen element to be substituted is a fluorine element in consideration of water repellency. Preferably there is.

  The chemical solution for forming a water repellent protective film may contain two or more silicon compounds represented by the general formula [1].

  Further, when the chemical solution for forming the water repellent protective film is in a state of being maintained at a temperature of 10 ° C. to 160 ° C., the silicon compound is likely to be dissolved in the chemical solution, so that a more uniform chemical solution is obtained. The temperature is preferably 50 to 120 ° C. In the protective film forming step described later, it is preferable that the chemical solution is maintained at a temperature of 10 ° C. to 160 ° C. because the protective film can be easily formed in a shorter time. In particular, 50 to 120 ° C. is preferable.

It is more preferable that the number of X of the silicon compound represented by 4-a in the general formula [1] is 1 (that is, a = 3) because the protective film can be formed uniformly. Moreover, among the silicon compounds represented by the general formula [1], R ¹ is one hydrocarbon group having 4 to 18 carbon atoms in which some or all of the hydrogen elements may be substituted with halogen elements. A compound composed of two methyl groups (that is, a compound represented by the following general formula [2]) is preferable because it has a higher reactivity with the silanol groups on the surface of the concavo-convex pattern and the wafer surface. This is because the steric hindrance due to the hydrophobic group has a great influence on the reactivity of the silicon compound with the silanol group on the uneven pattern surface or wafer surface, and the hydrocarbon group bonded to the silicon element excludes the longest one. This is because the remaining two are preferably shorter.
R ² (CH ₃ ) ₂ SiX [2]
[In the formula [2], R ² is a monovalent hydrocarbon group having 4 to 18 carbon atoms in which some or all of the hydrogen elements may be replaced with halogen elements, and X is bonded to the silicon element. From the group consisting of a monovalent functional group in which the element is nitrogen, a monovalent functional group in which the element bonded to the silicon element is oxygen, a halogen group, a nitrile group, and —CO—NH—Si (CH ₃ ) ₃ At least one group selected. ]

In consideration of the reactivity of the silicon compound with respect to the silanol group on the wafer surface, the silicon compound is more preferably a silicon compound represented by the following general formula [3].
^{_{R 2 (CH 3) 2 Si}} -N (R 3) 2 [3]
[In the formula [3], R ² is a monovalent hydrocarbon group having 4 to 18 carbon atoms in which some or all of the hydrogen elements may be replaced by halogen elements, and R ³ is a methyl group, ethyl Group, propyl group, or butyl group. ]

Examples of the silicon compound represented by the general formula [3] include C ₄ H ₉ (CH ₃ ) ₂ SiN (CH ₃ ) ₂ , C ₅ H ₁₁ (CH ₃ ) ₂ SiN (CH ₃ ) ₂ , C _{6 H 13 (CH 3) 2} SiN (CH 3) 2, C 7 H 15 (CH 3) 2 SiN (CH 3) 2, C 8 H 17 (CH 3) 2 SiN (CH 3) 2, C 9 H ₁₉ (CH ₃ ) ₂ SiN (CH ₃ ) ₂ , C ₁₀ H ₂₁ (CH ₃ ) ₂ SiN (CH ₃ ) ₂ , C ₁₁ H ₂₃ (CH ₃ ) ₂ SiN (CH ₃ ) ₂ , C ₁₂ H ₂₅ ( CH ₃ ) ₂ SiN (CH ₃ ) ₂ , C ₁₃ H ₂₇ (CH ₃ ) ₂ SiN (CH ₃ ) ₂ , C ₁₄ H ₂₉ (CH ₃ ) ₂ SiN (CH ₃ ) ₂ , C ₁₅ H ₃₁ (CH _{3 ) 2 SiN (CH 3) 2} , _{16 H 33 (CH 3) 2} SiN (CH 3) 2, C 17 H 35 (CH 3) 2 SiN (CH 3) 2, C 18 H 37 (CH 3) 2 SiN (CH 3) 2, C 5 H _{11 (CH 3) HSiN (CH} 3) 2, C 6 H 13 (CH 3) HSiN (CH 3) 2, C 7 H 15 (CH 3) HSiN (CH 3) 2, C 8 H 17 (CH 3) _{HSiN (CH 3) 2, C} 9 H 19 (CH 3) HSiN (CH 3) 2, C 10 H 21 (CH 3) HSiN (CH 3) 2, C 11 H 23 (CH 3) HSiN (CH 3) ₂ , C ₁₂ H ₂₅ (CH ₃ ) HSiN (CH ₃ ) ₂ , C ₁₃ H ₂₇ (CH ₃ ) HSiN (CH ₃ ) ₂ , C ₁₄ H ₂₉ (CH ₃ ) HSiN (CH ₃ ) ₂ , C ₁₅ H _{31 (CH 3) HSiN (CH 3} ) 2, C 16 H 33 (CH 3) HSiN (CH 3) 2, C 17 H 35 (CH 3) HSiN (CH 3) 2, C 18 H 37 (CH 3) HSiN (CH ₃ ) ₂ , C ₂ F ₅ C ₂ H ₄ (CH ₃ ) ₂ SiN (CH ₃ ) ₂ , C ₃ F ₇ C ₂ H ₄ (CH ₃ ) ₂ SiN (CH ₃ ) ₂ , C ₄ F _{9 C 2 H 4 (CH 3)} 2 SiN (CH 3) 2, C 5 F 11 C 2 H 4 (CH 3) 2 SiN (CH 3) 2, C 6 F 13 C 2 H 4 (CH 3) 2 SiN _{(CH 3) 2, C 7} F 15 C 2 H 4 (CH 3) 2 SiN (CH 3) 2, C 8 F 17 C 2 H 4 (CH 3) 2 SiN (CH 3) 2, (C 2 H _{5) 3 SiN (CH 3)} 2, C 3 H 7 (C 2 _{5) 2 SiN (CH 3)} 2, C 4 H 9 (C 2 H 5) 2 SiN (CH 3) 2, C 5 H 11 (C 2 H 5) 2 SiN (CH 3) 2, C 6 H 13 _{(C 2 H 5) 2 SiN} (CH 3) 2, C 7 H 15 (C 2 H 5) 2 SiN (CH 3) 2, C 8 H 17 (C 2 H 5) 2 SiN (CH 3) 2, _{C 9 H 19 (C 2 H} 5) 2 SiN (CH 3) 2, C 10 H 21 (C 2 H 5) 2 SiN (CH 3) 2, C 11 H 23 (C 2 H 5) 2 SiN (CH _{3) 2, C 12 H 25} (C 2 H 5) 2 SiN (CH 3) 2, C 13 H 27 (C 2 H 5) 2 SiN (CH 3) 2, C 14 H 29 (C 2 H 5) _{2 SiN (CH 3) 2,} C 15 H 31 (C 2 H 5) 2 SiN _{CH 3) 2, C 16 H} 33 (C 2 H 5) 2 SiN (CH 3) 2, C 17 H 35 (C 2 H 5) 2 SiN (CH 3) 2, C 18 H 37 (C 2 H 5 ) ₂ SiN (CH ₃ ) ₂ , (C ₄ H ₉ ) ₃ SiN (CH ₃ ) ₂ , C ₅ H ₁₁ (C ₄ H ₉ ) ₂ SiN (CH ₃ ) ₂ , C ₆ H ₁₃ (C ₄ H ₉₎ ) ₂ SiN (CH ₃ ) ₂ , C ₇ H ₁₅ (C ₄ H ₉ ) ₂ SiN (CH ₃ ) ₂ , C ₈ H ₁₇ (C ₄ H ₉ ) ₂ SiN (CH ₃ ) ₂ , C ₉ H ₁₉ ( _{C 4 H 9) 2 SiN (} CH 3) 2, C 10 H 21 (C 4 H 9) 2 SiN (CH 3) 2, C 11 H 23 (C 4 H 9) 2 SiN (CH 3) 2, C ₁₂ H ₂₅ (C ₄ H ₉ ) ₂ SiN (CH ₃ ) ₂ , C ₁₃ H _{2 7} (C ₄ H ₉ ) ₂ SiN (CH ₃ ) ₂ , C ₁₄ H ₂₉ (C ₄ H ₉ ) ₂ SiN (CH ₃ ) ₂ , C ₁₅ H ₃₁ (C ₄ H ₉ ) ₂ SiN (CH ₃ ) ₂ C ₁₆ H ₃₃ (C ₄ H ₉ ) ₂ SiN (CH ₃ ) ₂ , C ₁₇ H ₃₅ (C ₄ H ₉ ) ₂ SiN (CH ₃ ) ₂ , C ₁₈ H ₃₇ (C ₄ H ₉ ) ₂ SiN ( CH ₃ ) ₂ , C ₅ H ₁₁ (CH ₃ ) Si [N (CH ₃ ) ₂ ] ₂ , C ₆ H ₁₃ (CH ₃ ) Si [N (CH ₃ ) ₂ ] ₂ , C ₇ H ₁₅ (CH ₃ ) Si [N (CH ₃ ) ₂ ] ₂ , C ₈ H ₁₇ (CH ₃ ) Si [N (CH ₃ ) ₂ ] ₂ , C ₉ H ₁₉ (CH ₃ ) Si [N (CH ₃ ) ₂ ] ₂ , C ₁₀ H ₂₁ (CH ₃ ) Si [N (CH ₃ ) ₂ ] ₂ , C ₁₁ H ₂₃ (CH _{3) Si [N (CH 3} ) 2] 2, C 12 H 25 (CH 3) Si [N (CH 3) 2] 2, C 13 H 27 (CH 3) Si [N (CH 3) 2] 2 , C ₁₄ H ₂₉ (CH ₃ ) Si [N (CH ₃ ) ₂ ] ₂ , C ₁₅ H ₃₁ (CH ₃ ) Si [N (CH ₃ ) ₂ ] ₂ , C ₁₆ H ₃₃ (CH ₃ ) Si [N (CH ₃ ) ₂ ] ₂ , C ₁₇ H ₃₅ (CH ₃ ) Si [N (CH ₃ ) ₂ ] ₂ , C ₁₈ H ₃₇ (CH ₃ ) Si [N (CH ₃ ) ₂ ] ₂ , C ₃ F _{7 C 2 H 4 (CH 3)} Si [N (CH 3) 2] 2, C 4 F 9 C 2 H 4 (CH 3) Si [N (CH 3) 2] 2, C 5 F 11 C 2 H 4 (CH ₃ ) Si [N (CH ₃ ) ₂ ] ₂ , C ₆ F ₁₃ C ₂ H ₄ (CH ₃ ) Si [N (CH _{3) 2] 2, C 7} F 15 C 2 H 4 (CH 3) Si [N (CH 3) 2] 2, C 8 F 17 C 2 H 4 (CH 3
) Si [N (CH ₃ ) ₂ ] ₂ , C ₆ H ₁₃ Si [N (CH ₃ ) ₂ ] ₃ , C ₇ H ₁₅ Si [N (CH ₃ ) ₂ ] ₃ , C ₈ H ₁₇ Si [N ( _{CH 3) 2] 3, C} 9 H 19 Si [N (CH 3) 2] 3, C 10 H 21 Si [N (CH 3) 2] 3, C 11 H 23 Si [N (CH 3) 2] ₃ , C ₁₂ H ₂₅ Si [N (CH ₃ ) ₂ ] ₃ , C ₁₃ H ₂₇ Si [N (CH ₃ ) ₂ ] ₃ , C ₁₄ H ₂₉ Si [N (CH ₃ ) ₂ ] ₃ , C ₁₅ H ₃₁ Si [N (CH ₃ ) ₂ ] ₃ , C ₁₆ H ₃₃ Si [N (CH ₃ ) ₂ ] ₃ , C ₁₇ H ₃₅ Si [N (CH ₃ ) ₂ ] ₃ , C ₁₈ H ₃₇ Si [N ( _{CH 3) 2] 3, C} 4 F 9 C 2 H 4 Si [N (CH 3) 2] 3, C 5 F 1 _{C 2 H 4 Si [N (} CH 3) 2] 3, C 6 F 13 C 2 H 4 Si [N (CH 3) 2] 3, C 7 F 15 C 2 H 4 Si [N (CH 3) 2 _{] 3, C 8 F 17 C} 2 H 4 Si [N (CH 3) 2] 3, C 4 H 9 (CH 3) 2 SiN (C 2 H 5) 2, C 5 H 11 (CH 3) 2 SiN (C ₂ H ₅ ) ₂ , C ₆ H ₁₃ (CH ₃ ) ₂ SiN (C ₂ H ₅ ) ₂ , C ₇ H ₁₅ (CH ₃ ) ₂ SiN (C ₂ H ₅ ) ₂ , C ₈ H ₁₇ (CH ₃ ) ₂ SiN (C ₂ H ₅ ) ₂ , C ₉ H ₁₉ (CH ₃ ) ₂ SiN (C ₂ H ₅ ) ₂ , C ₁₀ H ₂₁ (CH ₃ ) ₂ SiN (C ₂ H ₅ ) ₂ , C _{11 H 23 (CH 3) 2 SiN} (C 2 H 5) 2, C 12 H 25 (CH 3) 2 SiN (C ₂ H ₅ ) ₂ , C ₁₃ H ₂₇ (CH ₃ ) ₂ SiN (C ₂ H ₅ ) ₂ , C ₁₄ H ₂₉ (CH ₃ ) ₂ SiN (C ₂ H ₅ ) ₂ , C ₁₅ H ₃₁ (CH ₃ ) ₂ SiN (C ₂ H ₅ ) ₂ , C ₁₆ H ₃₃ (CH ₃ ) ₂ SiN (C ₂ H ₅ ) ₂ , C ₁₇ H ₃₅ (CH ₃ ) ₂ SiN (C ₂ H ₅ ) ₂ , C _{18 H 37 (CH 3) 2 SiN} (C 2 H 5) 2, C 4 F 9 C 2 H 4 (CH 3) 2 SiN (C 2 H 5) 2, C 4 F 9 C 2 H 4 (CH 3) ₂ SiN (C ₂ H ₅ ) ₂ , C ₅ F ₁₁ C ₂ H ₄ (CH ₃ ) ₂ SiN (C ₂ H ₅ ) ₂ , C ₆ F ₁₃ C ₂ H ₄ (CH ₃ ) ₂ SiN (C ₂ H _{5) 2, C 7 F 15} C 2 H 4 (CH 3) 2 SiN (C 2 H 5) 2 _{C 8 F 17 C 2 H 4} (CH 3) 2 SiN (C 2 H 5) 2, (C 2 H 5) 3 SiN (C 2 H 5) 2, C 3 H 7 (C 2 H 5) 2 SiN _{(C 2 H 5) 2,} C 4 H 9 (C 2 H 5) 2 SiN (C 2 H 5) 2, C 5 H 11 (C 2 H 5) 2 SiN (C 2 H 5) 2, C 6 _{H 13 (C 2 H 5)} 2 SiN (C 2 H 5) 2, C 7 H 15 (C 2 H 5) 2 SiN (C 2 H 5) 2, C 8 H 17 (C 2 H 5) 2 SiN (C ₂ H ₅ ) ₂ , C ₉ H ₁₉ (C ₂ H ₅ ) ₂ SiN (C ₂ H ₅ ) ₂ , C ₁₀ H ₂₁ (C ₂ H ₅ ) ₂ SiN (C ₂ H ₅ ) ₂ , C _{11 H 23 (C 2 H 5)} 2 SiN (C 2 H 5) 2, C 12 H 25 (C 2 H 5) 2 SiN (C 2 _{5) 2, C 13 H 27} (C 2 H 5) 2 SiN (C 2 H 5) 2, C 14 H 29 (C 2 H 5) 2 SiN (C 2 H 5) 2, C 15 H 31 (C _{2 H 5) 2 SiN (C} 2 H 5) 2, C 16 H 33 (C 2 H 5) 2 SiN (C 2 H 5) 2, C 17 H 35 (C 2 H 5) 2 SiN (C 2 H ₅ ) ₂ , C ₁₈ H ₃₇ (C ₂ H ₅ ) ₂ SiN (C ₂ H ₅ ) ₂ , (C ₄ H ₉ ) ₃ SiN (C ₂ H ₅ ) ₂ , C ₅ H ₁₁ (C ₄ H ₉ ) ₂ SiN (C ₂ H ₅ ) ₂ , C ₆ H ₁₃ (C ₄ H ₉ ) ₂ SiN (C ₂ H ₅ ) ₂ , C ₇ H ₁₅ (C ₄ H ₉ ) ₂ SiN (C ₂ H ₅ ) ₂ , _{C 8 H 17 (C 4 H} 9) 2 SiN (C 2 H 5) 2, C 9 H 19 (C 4 H 9) 2 S iN (C ₂ H ₅ ) ₂ , C ₁₀ H ₂₁ (C ₄ H ₉ ) ₂ SiN (C ₂ H ₅ ) ₂ , C ₁₁ H ₂₃ (C ₄ H ₉ ) ₂ SiN (C ₂ H ₅ ) ₂ , C _{12 H 25 (C 4 H 9} ) 2 SiN (C 2 H 5) 2, C 13 H 27 (C 4 H 9) 2 SiN (C 2 H 5) 2, C 14 H 29 (C 4 H 9) 2 SiN (C ₂ H ₅ ) ₂ , C ₁₅ H ₃₁ (C ₄ H ₉ ) ₂ SiN (C ₂ H ₅ ) ₂ , C ₁₆ H ₃₃ (C ₄ H ₉ ) ₂ SiN (C ₂ H ₅ ) ₂ , C ₁₇ H ₃₅ (C ₄ H ₉ ) ₂ SiN (C ₂ H ₅ ) ₂ , C ₁₈ H ₃₇ (C ₄ H ₉ ) ₂ SiN (C ₂ H ₅ ) ₂ or the like, or the above nitrogen element Examples thereof include compounds in which a methyl group or an ethyl group is replaced with a propyl group or a butyl group.

  Moreover, it is preferable that the silicon compound density | concentration in the said chemical | medical solution for water-repellent protective film formation is 0.1-4 mass%. In the chemical solution of the present invention, excellent water repellency can be imparted to the wafer surface as long as the silicon compound concentration is 0.1% by mass or more due to the effect of promoting the silane coupling reaction by the solvent (I) as described above. This is preferable because it is possible. In consideration of the cost of the chemical solution, the concentration of the silicon compound is preferably low, and the upper limit is preferably 4% by mass.

  The chemical solution preferably further contains an acid in order to promote the reaction between the silicon compound as the protective film forming agent and the silanol groups on the concave / convex pattern surface or the wafer surface. As such an acid, a water-free acid such as trifluoroacetic acid, trifluoroacetic anhydride, pentafluoropropionic acid, pentafluoropropionic anhydride, trifluoromethanesulfonic acid, trifluoromethanesulfonic anhydride, sulfuric acid, hydrogen chloride and the like is preferable. Used for. In particular, in consideration of the reaction promoting effect, acids such as trifluoroacetic acid, trifluoroacetic anhydride, trifluoromethanesulfonic acid, trifluoromethanesulfonic anhydride, sulfuric acid, and hydrogen chloride are preferable, and the acid may not contain moisture. preferable.

In particular, when the number of carbon atoms of the hydrophobic group R ¹ in the general formula [1] increases, the reactivity of the silicon compound with respect to silanol groups on the uneven pattern surface or wafer surface may decrease due to steric hindrance. In this case, by adding an acid that does not contain water, the reaction between the silanol group on the uneven pattern surface and the wafer surface and the silicon compound is promoted, which compensates for the decrease in reactivity due to steric hindrance of the hydrophobic group There is.

  The addition amount of the acid is preferably 0.01 to 100% by mass with respect to 100% by mass of the total amount of the silicon compound. When the amount added is small, it is difficult to obtain a reaction promoting effect. Moreover, even if it adds excessively, the reaction promotion effect will not improve, and conversely, the reaction promotion effect may fall. Further, there is a concern that the impurities remain on the surface of the concave / convex pattern or the wafer surface as impurities. For this reason, 0.01-100 mass% is preferable, and, as for the addition amount of the said acid, More preferably, it is 0.1-50 mass%. Considering this, the amount of acid added to the total amount of the chemical solution is preferably 0.0001 to 50% by mass, more preferably 0.001 to 33% by mass with respect to 100% by mass of the total amount of the chemical solution.

  The present invention also provides a water-repellent protective film-forming chemical solution kit for obtaining the above-described water-repellent protective film-forming chemical solution, wherein the chemical solution kit comprises a silicon compound represented by the general formula [1] and a solvent. Water repellent, characterized in that it comprises a treatment liquid A having (I) and / or solvent (II), an acid, and a treatment liquid B having the solvent (I) and / or solvent (II). This is a chemical solution kit for forming a protective film.

  The said chemical | medical solution kit is what makes the said chemical | medical solution by mixing the processing liquid A and the processing liquid B which were stored separately, and a silicon compound, solvent (I), and solvent (II) are the above-mentioned. The thing similar to what was described with the chemical | medical solution for water-repellent protective film formation can be used. In addition, the content ratio of the solvent (I) and the solvent (II) contained in the treatment liquids A and B is not particularly limited, but when the treatment liquid A and the treatment liquid B are mixed to obtain the chemical liquid, the chemical liquid The solvent (I) and the solvent (II) contained in are prepared so as to be composed of 40:60 to 97: 3 by mass ratio.

  The solvent (I) used in the chemical solution kit is preferably a lactone solvent that has high polarity and is excellent in the reaction promoting effect.

  Moreover, it is preferable that the silicon compound used with the said chemical | medical solution kit is a silicon compound represented by the said General formula [2].

  Moreover, it is preferable that the silicon compound used with the said chemical | medical solution kit is a silicon compound represented by the said General formula [3].

Further, the present invention provides a step shown below in the cleaning of a wafer having a concavo-convex pattern on the surface and containing silicon oxide on at least the concave surface of the concavo-convex pattern,
Cleaning the wafer surface with a cleaning liquid;
A water repellent protective film forming step of holding a water repellent protective film forming chemical in at least the concave portion of the wafer and forming a water repellent protective film on the concave surface;
A drying process to remove the liquid on the wafer surface;
A water-repellent protective film removing step for removing the water-repellent protective film from the surface of the recess, wherein the water-repellent protective film-forming chemical solution or the water-repellent protective film-forming chemical solution kit is included in the water-repellent protective film-forming step. The wafer cleaning method is characterized by using the obtained chemical solution for forming a water repellent protective film.

  Further, the water repellent protective film removing step is selected from irradiating the wafer surface with light, heating the wafer, irradiating the wafer surface with plasma, exposing the wafer surface to ozone, and corona discharging the wafer. It is preferable to carry out by at least one processing method.

  By using the chemical solution for forming a water-repellent protective film of the present invention, a chemical kit for obtaining the chemical solution, and a wafer cleaning method using the chemical solution or a chemical solution obtained from the chemical solution kit, the surface has an uneven pattern. Since the water-repellent protective film can be quickly formed on the surface of the wafer containing silicon oxide on at least the concave surface of the concave-convex pattern, and more excellent water-repellent performance can be imparted. Succeeds in suppressing pattern collapse. By applying the present invention, even when a silicon compound having a large hydrophobic group is used to form a water-repellent protective film, an insoluble component is not generated, and a uniform chemical solution for forming a water-repellent protective film can be obtained. In addition, it is possible to impart excellent water repellency to the wafer surface.

The schematic diagram when the wafer 1 by which the surface was made into the surface which has the uneven | corrugated pattern 2 is seen. The schematic diagram which showed a part of a-a 'cross section in FIG. The schematic diagram of the state in which the recessed part 4 hold | maintained the chemical | medical solution 8 for water-repellent protective film formation in the water-repellent protective film formation process. The schematic diagram of the state by which the liquid 9 was hold | maintained at the recessed part 4 in which the water-repellent protective film 10 was formed.

A wafer having an uneven pattern on the surface is often obtained by the following procedure. First, after applying a resist to a smooth wafer surface, the resist is exposed through a resist mask, and the resist having a desired concavo-convex pattern is produced by etching away the exposed resist or the resist that has not been exposed. To do. Moreover, the resist which has an uneven | corrugated pattern can be obtained also by pressing the mold which has a pattern to a resist. Next, the wafer is etched. At this time, the wafer surface corresponding to the concave portion of the resist pattern is selectively etched. Finally, when the resist is removed, a wafer having a concavo-convex pattern is obtained.

  Examples of the wafer include a silicon wafer and a silicon wafer on which a silicon oxide film is formed by a thermal oxidation method, a CVD method, a sputtering method, or the like. Further, a wafer composed of a plurality of components including silicon oxide, a silicon carbide wafer, and a wafer in which a silicon oxide film is formed on the wafer can be used as the wafer. Furthermore, a silicon oxide film may be formed on a wafer that does not contain silicon elements, such as a sapphire wafer, various compound semiconductor wafers, and a plastic wafer. The chemical solution is protected on the surface of the wafer containing silicon oxide, the surface of the silicon oxide film formed on the wafer, and the surface of the wafer or the portion of the concavo-convex pattern formed on the film where silicon oxide exists. A film can be formed to make it water repellent.

  The wafer having a concavo-convex pattern on the surface obtained as described above is cleaned in the cleaning step in order to remove particles and the like. In the wafer cleaning method of the present invention, in order to perform efficient cleaning without causing pattern collapse, at least the cleaning step and the water-repellent protective film forming step are always held at least in the recesses of the wafer. In the state. In addition, when the water-repellent protective film-forming chemical solution held in the concave portion of the wafer is replaced with another liquid after the water-repellent protective film forming step, the liquid is always held in at least the concave portion of the wafer as described above. It is preferable to carry out in the state. In the present invention, as long as the cleaning liquid, the chemical liquid, and other liquids can be held in at least the concave portions of the concave / convex pattern of the wafer, the cleaning liquid, chemical liquid, and other liquid supply methods (hereinafter, these methods are generically referred to). In some cases, “cleaning method” may be described). As a wafer cleaning method, a single wafer represented by spin cleaning (processing) in which a wafer is cleaned (processed) one by one by supplying liquid to the vicinity of the center of rotation while holding and rotating the wafer substantially horizontal. Examples thereof include a batch system in which a plurality of wafers are immersed and cleaned (processed) in a cleaning tank. It should be noted that the form of the cleaning liquid, the chemical liquid, and the other liquid when supplying the cleaning liquid, the chemical liquid, and the other liquid to at least the concave portion of the concave / convex pattern of the wafer may be a liquid when held in the concave portion. For example, there are liquid and vapor.

  Examples of the cleaning liquid used in the cleaning step include water, water in which at least one of organic solvents, acids, alkalis, surfactants, hydrogen peroxide, and ozone is mixed as a main component (for example, water For example, an aqueous cleaning liquid or an organic solvent.

  In the cleaning step, when an aqueous cleaning liquid containing water is used as the cleaning liquid, the aqueous cleaning liquid is held at least in the recess and comes into contact with the surface of the recess. In the case of a wafer containing silicon oxide on the concave surface, silanol groups are formed on a part of the surface by contact with an aqueous cleaning solution. Since the silicon compound contained in the chemical solution for forming a water-repellent protective film of the present invention has a large hydrophobic group, when forming a protective film by reacting with the silanol group formed as described above, the silicon compound is formed on the concave surface of the wafer. It is possible to exhibit excellent water repellency.

  Oxidation of the wafer surface as described above proceeds even when pure water at room temperature is used as the aqueous cleaning liquid, but if a strongly acidic aqueous solution is used as the aqueous cleaning liquid or the temperature of the aqueous cleaning liquid is increased, Since it tends to proceed, an acid may be added to the aqueous cleaning solution for the purpose of promoting the oxidation, or the temperature of the aqueous cleaning solution may be increased. Further, hydrogen peroxide or ozone may be added for the purpose of promoting the oxidation.

  Examples of the organic solvent which is one of the preferable examples of the cleaning liquid include hydrocarbons, esters, ethers, ketones, halogen-containing solvents, sulfoxide solvents, lactone solvents, carbonate solvents, alcohols. And derivatives of polyhydric alcohols, nitrogen element-containing solvents, and the like.

  Examples of acids that can be mixed in the aqueous cleaning liquid include inorganic acids and organic acids. Examples of inorganic acids include hydrofluoric acid, buffered hydrofluoric acid, sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, etc. Examples of organic acids include methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid , Acetic acid, trifluoroacetic acid, pentafluoropropionic acid and the like. Examples of the alkali that may be mixed in the aqueous cleaning liquid include ammonia and choline. Examples of the oxidizing agent that may be mixed in the aqueous cleaning liquid include ozone and hydrogen peroxide.

  A plurality of cleaning liquids may be used as the cleaning liquid. For example, a cleaning solution containing an acid aqueous solution or an alkaline aqueous solution and the organic solvent may be used as the cleaning solution, and the cleaning may be performed in the order of a cleaning solution containing an acid aqueous solution or an alkaline aqueous solution → the organic solvent. Further, for example, the cleaning may be performed in the order of a cleaning solution containing an acid aqueous solution or an alkali aqueous solution → an aqueous cleaning solution → the organic solvent.

  In the cleaning step, the cleaning liquid may be held at a temperature of 10 ° C. or higher and lower than the boiling point of the cleaning liquid. For example, when the cleaning liquid contains an aqueous acid solution, particularly preferably a solution containing an aqueous acid solution and an organic solvent having a boiling point of 100 ° C. or higher, the protective film can be formed in a short time by increasing the temperature of the cleaning liquid to around the boiling point of the cleaning liquid. It is preferable because it is easy to form.

  If the used cleaning liquid is removed from the wafer surface by drying or the like after the cleaning step, pattern collapse tends to occur when the width of the concave portion is small and the aspect ratio of the convex portion is large. The concavo-convex pattern is defined as shown in FIGS. FIG. 1 is a schematic view of a wafer 1 whose surface has a concavo-convex pattern 2 as viewed from the perspective, and FIG. 2 shows a part of the a-a ′ cross section in FIG. 1. As shown in FIG. 2, the width 5 of the concave portion is indicated by the interval between the convex portion 3 and the convex portion 3, and the aspect ratio of the convex portion is expressed by dividing the height 6 of the convex portion by the width 7 of the convex portion. Is done. Pattern collapse tends to occur when the width of the recess is 70 nm or less, particularly 45 nm or less, and the aspect ratio is 4 or more, particularly 6 or more.

  The cleaning liquid held in at least the concave portion of the concave / convex pattern of the wafer in the cleaning step is replaced with a chemical solution for forming the water repellent protective film in the water repellent protective film forming step. FIG. 3 is a schematic view showing a state in which the recess 4 holds the protective film forming chemical 8 in the water repellent protective film forming step. The wafer in the schematic diagram of FIG. 3 shows a part of the a-a ′ cross section of FIG. 1. The protective film-forming chemical solution is held in the recess 4, and a protective film is formed on the surface of the recess 4, thereby making the surface water repellent. Note that the protective film of the present invention does not necessarily have to be formed continuously, and does not necessarily have to be formed uniformly, but because it can impart better water repellency, More preferably, it is uniformly formed.

  After the water repellent protective film forming step, the chemical solution held in at least the concave portion of the concave / convex pattern may be replaced with a rinse solution different from the chemical solution, and then the drying step may be performed. Examples of the rinsing liquid include an aqueous cleaning liquid composed of an aqueous solution, an organic solvent, a mixture of the aqueous cleaning liquid and an organic solvent, and a mixture of at least one of an acid, an alkali, and a surfactant. Or a compound in which a silicon compound or an acid contained in the chemical solution for forming a protective film is added so as to have a lower concentration than the chemical solution.

  Examples of the organic solvent which is one of preferred examples of the rinsing liquid include hydrocarbons, esters, ethers, ketones, halogen-containing solvents, sulfoxide solvents, lactone solvents, carbonate solvents, alcohols. , Derivatives of polyhydric alcohols, nitrogen element-containing solvents, and the like.

  When water is used as the rinsing liquid, at least the concave surface of the concavo-convex pattern made water repellent by the chemical liquid has a large contact angle θ with the liquid, and the capillary force acting on the concave part is reduced. This is preferable because dirt is less likely to remain on the surface. A plurality of cleaning liquids may be used as the rinsing liquid. For example, an organic solvent (preferably containing a water-soluble organic solvent) and an aqueous cleaning solution can be used in succession.

  FIG. 4 shows a schematic view when the liquid 9 is held in the recess 4 that has been made water-repellent by the chemical solution for forming the water-repellent protective film. The wafer in the schematic diagram of FIG. 4 shows a part of the a-a ′ cross section of FIG. 1. A water repellent protective film 10 is formed on the surface of the recess 4. At this time, the liquid 9 held in the recess 4 may be the chemical liquid, a rinse liquid after replacement from the chemical liquid, or a liquid in the middle of replacement (mixed liquid of the chemical liquid and the rinse liquid). The water repellent protective film 10 is held on the wafer surface even when the liquid 9 is removed from the recess 4.

  When a water-repellent protective film is present on the surface of the recess as in the recess 4 of FIG. 4, the contact angle between the surface of the recess and the liquid held in the recess is increased, and the capillary force acting on the recess is reduced.

  As shown in FIG. 4, when the protective film 10 is formed on the surface of the recess, the contact angle when assuming that water is held on the surface is larger than the capillary force formula described in the background art. Since the capillary force acting on the concave portion is small, pattern collapse is less likely to occur, which is preferable.

Next, a drying process is performed. In this step, the liquid held on the uneven pattern surface is removed by drying. The drying is performed by a known drying method such as natural drying, air drying, N ₂ gas drying, spin drying method, IPA (2-propanol) vapor drying, Marangoni drying, heat drying, air drying, hot air drying, vacuum drying, and the like. Preferably it is done.

  Prior to the drying step, the liquid held in the recess is the chemical solution, the rinse solution, or a mixed solution of the chemical solution and the rinse solution. The liquid mixture containing the chemical liquid may be a liquid in the middle of replacing the chemical liquid with the rinse liquid, or may be a liquid mixture obtained by previously mixing the chemical liquid with the rinse liquid. In order to efficiently remove the liquid, the retained liquid may be drained and removed, and then the remaining liquid may be dried.

  Next, the water repellent protective film removing step is performed. When the protective film 10 is removed, it is effective to cut the C—C bond and C—F bond in the protective film. The method is not particularly limited as long as it can cut the bond, for example, irradiating the wafer surface with light, heating the wafer, exposing the wafer to ozone, irradiating the wafer surface with plasma, For example, corona discharge on the wafer surface may be mentioned.

When the protective film 10 is removed by light irradiation, it is effective to cut the C—C bond and the C—F bond in the protective film 10, and for this purpose, their binding energy is 83 kcal / mol. It is preferable to irradiate ultraviolet rays including wavelengths shorter than 340 nm and 240 nm, which are energy corresponding to 116 kcal / mol. As this light source, a metal halide lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, an excimer lamp, a carbon arc, or the like is used. If the ultraviolet irradiation intensity is a metal halide lamp, for example, measurement with an illuminometer (irradiance intensity meter UM-10 manufactured by Konica Minolta Sensing, light receiving unit UM-360 [peak sensitivity wavelength: 365 nm, measurement wavelength range: 310 to 400 nm]) 100 mW / cm ² or more is preferable in value, 200 mW / cm ² or more is particularly preferable. When the irradiation intensity is less than 100 mW / cm ² , it takes a long time to remove the protective film 10. In addition, a low-pressure mercury lamp is preferable because ultraviolet rays having a shorter wavelength are irradiated, and thus the protective film 10 can be removed in a short time even if the irradiation intensity is low.

  Further, when the protective film 10 is removed by light irradiation, ozone is generated at the same time as the constituent components of the protective film 10 are decomposed by ultraviolet rays, and the constituent components of the protective film 10 are oxidized and volatilized by the ozone. Is particularly preferable. As this light source, a low-pressure mercury lamp or an excimer lamp is used. Further, the wafer may be heated while irradiating light.

  When the wafer is heated, it is preferable to heat the wafer at 400 to 700 ° C, preferably 500 to 700 ° C. The heating time is preferably 1 to 60 minutes, preferably 10 to 30 minutes. In this process, ozone exposure, plasma irradiation, corona discharge, etc. may be used in combination. Further, light irradiation may be performed while heating the wafer.

  Methods for removing the protective film by heating include a method of bringing a wafer into contact with a heat source and a method of placing the wafer in a heated atmosphere such as a heat treatment furnace. The method of placing the wafer in a heated atmosphere is easy to operate because it is easy to uniformly apply energy for removing the protective film to the wafer surface even when processing a plurality of wafers. This is an industrially advantageous method that requires a short processing time and a high processing capacity.

  When the wafer is exposed to ozone, ozone generated by ultraviolet irradiation with a low-pressure mercury lamp or the like or low-temperature discharge with a high voltage may be provided to the wafer surface. The wafer may be irradiated with light while being exposed to ozone, or may be heated.

  By combining the light irradiation, heating, ozone exposure, plasma irradiation, and corona discharge, the protective film on the wafer surface can be efficiently removed.

  Making the surface of the wafer a surface having a concavo-convex pattern, replacing the cleaning liquid held at least in the concave portion of the concavo-convex pattern with another cleaning liquid, various studies have been made in other literatures, etc. and already established techniques Thus, in this example, the evaluation was mainly performed on the protective film forming chemical solution.

Formulas mentioned in the background art
P = 2 × γ × cos θ / S
(Wherein γ is the surface tension of the liquid held in the recess, θ is the contact angle between the recess surface and the liquid held in the recess, and S is the width of the recess.)
As can be seen from the above, the absolute value of the capillary force P causing the pattern collapse greatly depends on the contact angle of the liquid with respect to the wafer surface, that is, the contact angle of the droplet and the surface tension of the liquid. In the case of the liquid held in the concave portion 4 of the concave-convex pattern 2, the contact angle of the droplet and the capillary force acting on the concave portion, which can be considered as equivalent to the pattern collapse, have a correlation. The capillary force may be derived from the evaluation of the contact angle of the droplet of the water repellent protective film 10 formed on the surface. In the examples, water, which is a typical water-based cleaning liquid, was used as the liquid.

  The contact angle of water droplets is evaluated by dropping a few μl of water droplets on the surface of the sample (base material) as described in JIS R 3257 “Testing method for wettability of substrate glass surface”. This is done by measuring the angle. However, in the case of a wafer having a pattern, the contact angle becomes very large. This is because a Wenzel effect and a Cassie effect occur, and the contact angle is affected by the surface shape (roughness) of the substrate, and the apparent contact angle of water droplets increases. Therefore, in the case of a wafer having a concavo-convex pattern on the surface, the contact angle of the protective film 10 itself formed on the concavo-convex pattern surface cannot be accurately evaluated.

Therefore, in this embodiment, the chemical solution is applied to a wafer having a smooth surface, a protective film is formed on the wafer surface, and the protective film is formed on the surface of the wafer 1 on which the uneven pattern 2 is formed. The film 10 was considered and various evaluations were performed. In this example, a “silicon wafer with SiO ₂ film” (indicated as SiO _{2 in the} table) having a silicon oxide layer on a silicon wafer having a smooth surface was used as the wafer having a smooth surface.

  Details are described below. In the following, a method for evaluating a wafer provided with a chemical solution for forming a protective film, preparation of the chemical solution for forming the protective film, and an evaluation result after providing the chemical solution for forming a protective film on the wafer are described.

[Evaluation method of wafer provided with chemical solution for forming protective film]
The following evaluations (1) to (3) were performed as methods for evaluating a wafer provided with a chemical solution for forming a protective film.

(1) Contact angle evaluation of the protective film formed on the wafer surface About 2 μl of pure water is placed on the surface of the wafer on which the protective film is formed, and the angle (contact angle) formed between the water droplet and the wafer surface is measured by a contact angle meter (Kyowa). The contact angle was measured with Interface Science: CA-X type.

(2) Removability of protective film The sample was irradiated with UV light from a low-pressure mercury lamp for 1 minute under the following conditions. A sample in which the contact angle of water droplets was 10 ° or less after irradiation was regarded as acceptable.
・ Lamp: Sen Special Light Source PL2003N-10
Illuminance: 15 mW / cm ² (distance from light source to sample is 10 mm)

(3) Evaluation of surface smoothness of wafer after removal of protective film Surface observation was performed with an atomic force electron microscope (Seiko-Electronics: SPI3700, 2.5 μm square scan), and centerline average surface roughness: Ra (nm) was determined. Asked. Ra is a three-dimensional extension of the centerline average roughness defined in JIS B 0601 to the measurement surface. “The absolute value of the deviation from the reference surface to the specified surface is averaged. The value was calculated by the following formula. If the Ra value on the wafer surface after removing the protective film was 1 nm or less, the wafer surface was not eroded by the cleaning, and no residue of the protective film was present on the wafer surface.
Here, X _L , X _R , Y _B , and Y _T indicate measurement ranges of the X coordinate and the Y coordinate, respectively. S ₀ is an area when the measurement surface is ideally flat, and is a value of (X _R −X _L ) × (Y _B −Y _T ). Moreover, F (X, Y) is, the measurement point (X, Y) in height, _{Z 0} represents the average height within the measurement surface.

[Example 1]
(1) Preparation of chemical solution for forming protective film Octyldimethyldimethylaminosilane [C ₈ H ₁₇ (CH ₃ ) ₂ SiN (CH ₃ ) ₂ ] as a silicon compound; 0.5 g, trifluoroacetic anhydride [(CF ₃ CO as an acid) ) ₂ O]; 0.18 g, solvent (I) as γ- butyrolactone (hereinafter, may be referred to as "GBL"); 89.388g and solvent (II) as dipropylene glycol monomethyl ether acetate (hereinafter " All may be mixed at room temperature using a non-aqueous solvent mixed with 9.932 g [CH ₃ CH (OCH ₃ ) CH ₂ OCH ₂ CH (OCOCH ₃ ) CH ₃ ]; , The concentration of the silicon compound with respect to the total amount of the chemical solution for forming the protective film (hereinafter referred to as “silicon compound concentration”) is 0 5% by mass, concentration of acid with respect to the total amount of silicon compound (hereinafter referred to as “acid concentration with respect to silicon compound”) is 36% by mass, concentration of acid with respect to the total amount of chemical solution for forming a protective film (hereinafter referred to as “acid concentration in chemical solution”) Is obtained as 0.18% by mass, and a non-aqueous solvent (I) and solvent (II) mass ratio is 90:10. It was confirmed that the obtained chemical solution for forming a protective film was a uniform solution free of insoluble components of the silicon compound by visual observation at 20 ° C. In addition, the appearance of the chemical solution as described above is described as “uniform” in Table 1, and there is an insoluble component of the silicon compound by visual observation. Describe.

(2) Cleaning of wafer A silicon wafer with a smooth silicon oxide film (a silicon wafer having a thermal oxide film layer having a thickness of 1 μm on the surface) is immersed in a 1% by mass hydrofluoric acid aqueous solution for 2 minutes at room temperature and then immersed in pure water. It was immersed in 2-propanol for 1 minute for 1 minute.

(3) Surface treatment of the wafer surface with a protective film forming chemical solution The silicon wafer with the silicon oxide film was added to the protective film forming chemical solution prepared in the above-mentioned “(1) Preparation of protective film forming chemical solution” at 20 ° C. Immerse for a minute. Thereafter, the wafer was immersed in 2-propanol at room temperature for 1 minute, and then immersed in pure water for 1 minute. Finally, the wafer was taken out from the pure water and air was blown to remove the pure water on the surface.

  When the obtained wafer was evaluated in the manner described in “Method for evaluating wafer provided with protective film forming chemical solution”, as shown in Table 1, the initial contact angle before the surface treatment was less than 10 °. However, the contact angle after the surface treatment was 103 °, showing an excellent water repellency imparting effect. Moreover, the contact angle after UV irradiation was less than 10 °, and the protective film could be removed. Furthermore, the Ra value of the wafer after UV irradiation was less than 0.5 nm, and it was confirmed that the wafer was not eroded during cleaning, and that no residue of the water-repellent protective film remained after UV irradiation.

[Examples 2 to 6]
The type of the solvent (II) used in Example 1, the mass ratio of the solvent (I) and the solvent (II) in the non-aqueous solvent was appropriately changed, and the wafer was subjected to a surface treatment and further evaluated. The results are shown in Table 1. In Table 1, EHA means ethyl hexyl acetate and PGMEA means propylene glycol monomethyl ether acetate. In all examples and comparative examples, the temperature of the chemical solution when the appearance was evaluated was 20 ° C.

[Example 7]
Octyldimethyldimethylaminosilane [C ₈ H ₁₇ (CH ₃ ) ₂ SiN (CH ₃ ) ₂ ] as the silicon compound; 0.5 g, GBL as the solvent (I); 44.694 g and DPGMEA as the solvent (II); 4.966 g All were mixed at room temperature using a non-aqueous solvent mixed with to prepare a treatment liquid A. Further, trifluoroacetic anhydride [(CF ₃ CO) ₂ O]; 0.18 g as an acid, GBL as a solvent (I); 44.694 g, and DPGMEA as a solvent (II); All were mixed at room temperature to prepare a treatment solution B. The treatment liquid A and the treatment liquid B are mixed at room temperature and stirred for about 5 minutes. The silicon compound concentration is 0.5 mass%, the acid concentration with respect to the silicon compound is 36 mass%, and the acid concentration in the chemical liquid is 0.18 mass. %, A chemical solution for forming a protective film having a mass ratio of the nonaqueous solvent (I) to the solvent (II) of 90:10 was obtained. When the surface treatment of the wafer was performed in the same manner as in Example 1 using the obtained protective film-forming chemical, as shown in Table 1, the initial contact angle before the surface treatment was less than 10 °. The contact angle after the treatment was 103 °, showing an excellent water repellency imparting effect. Moreover, the contact angle after UV irradiation was less than 10 °, and the protective film could be removed. Furthermore, the Ra value of the wafer after UV irradiation was less than 0.5 nm, and it was confirmed that the wafer was not eroded during cleaning, and that no residue of the water-repellent protective film remained after UV irradiation.

[Comparative Example 1]
A chemical solution for forming a protective film was prepared in the same procedure as in Example 1 except that only GBL was used as the non-aqueous solvent. The obtained protective film-forming chemical was visually non-uniform at 20 ° C.

[Comparative Example 2]
Trimethylsilyldimethylamine [(CH ₃ ) ₃ SiN (CH ₃ ) ₂ ]; 0.5 g as a silicon compound, trifluoroacetic anhydride [(CF ₃ CO) ₂ O] as an acid; 0.18 g, GBL as a solvent (I) 89.388 g and DPGMEA as solvent (II); using non-aqueous solvent mixed with 9.932 g, all are mixed at room temperature and stirred for about 5 minutes, so that the silicon compound concentration is 0.5% by mass; A protective film-forming chemical solution having a mass ratio of non-aqueous solvent (I) to solvent (II) of 90:10 was obtained. In addition, it confirmed visually that the obtained chemical | medical solution for protective film formation was uniform in 20 degreeC.

  Then, when the surface treatment of the wafer was performed in the same manner as in Example 1, as shown in Table 1, the initial contact angle before the surface treatment was less than 10 °, but the contact angle after the surface treatment was 87 °. Although the water-repellent imparting effect was excellent, the contact angle was smaller than that of Example 1.

[Comparative Example 3]
Trifluoropropyldimethyldisilazane [[CF ₃ (CH ₂ ) ₂ (CH ₃ ) ₂ Si] ₂ NH] as a silicon compound; 0.5 g, trifluoroacetic anhydride [(CF ₃ CO) ₂ O] as an acid; 0 .18 g, GBL as solvent (I); 89.388 g and DPGMEA as solvent (II); 9.932 g mixed in a non-aqueous solvent at room temperature and stirred for about 5 minutes to A protective film-forming chemical solution having a compound concentration of 0.5% by mass and a mass ratio of 90:10 as solvent (I) and solvent (II) as a non-aqueous solvent was obtained. In addition, it confirmed visually that the obtained chemical | medical solution for protective film formation was uniform in 20 degreeC.

  Thereafter, the wafer surface treatment was performed in the same manner as in Example 1. As shown in Table 1, the initial contact angle before the surface treatment was less than 10 °, but the contact angle after the surface treatment was 92 °. Although the water-repellent imparting effect was excellent, the contact angle was smaller than that of Example 1.

  In Comparative Example 1 using only the lactone solvent (I) as the non-aqueous solvent, the silicon compound containing many carbon atoms in the hydrophobic group is not completely dissolved, and there is an insoluble component. The obtained chemical solution was non-uniform. On the other hand, in the above examples, since the non-aqueous solvent containing the solvent (I) and the solvent (II) in an appropriate ratio is used, none of the above insoluble components exist. It was uniform.

  Further, in the above examples, since a silicon compound containing a large number of carbon atoms in the hydrophobic group is used, a water repellency superior to Comparative Examples 2 and 3 in which the silicon compound is not used is applied to the wafer. Could be granted.

  Therefore, by applying the present invention, even when a silicon compound having a large hydrophobic group is used to form a water-repellent protective film, an insoluble component is not generated, and a uniform chemical solution for forming a water-repellent protective film is formed. Further, it is possible to impart more excellent water repellency to the wafer.

DESCRIPTION OF SYMBOLS 1 Wafer 2 Uneven | corrugated pattern on wafer surface 3 Convex part of pattern 4 Concave part of pattern 5 Concave width 6 Convex height 7 Convex part width 8 Water repellent protective film forming chemical 9 Liquid 10 Water repellent protective film

Claims (14)

A water repellency for forming a water repellent protective film on at least the concave surface of the wafer after the cleaning step and before the drying step of the wafer having a concave and convex pattern on the surface and containing silicon oxide on at least the concave surface of the concave and convex pattern A chemical for forming a protective film,
The chemical solution,
A protective film forming agent comprising only a silicon compound represented by the following general formula [1]:
A chemical solution containing a non-aqueous solvent,
The non-aqueous solvent is 40:60 by mass ratio of at least one solvent (I) selected from lactone solvents and carbonate solvents and a solvent (II) soluble in a silicon compound other than the solvent (I). It is comprised by -97: 3, The chemical | medical solution for water-repellent protective film formation characterized by the above-mentioned.
R ¹ _a SiX _4-a [1]
[In the formula [1], each R ¹ independently represents a hydrogen group, a monovalent hydrocarbon group having 1 to 18 carbon atoms in which some or all of the hydrogen elements may be replaced by halogen elements. The total number of carbon atoms contained in all the hydrocarbon groups bonded to the silicon element is at least one group selected from the group consisting of 6 or more. Further, X are each independently of the other isocyanate group, an amino group, an alkylamino group, a dialkylamino group, an isothiocyanate group, an azide group, acetamido _{group, -N (CH 3) C (} O) CH 3, -N _{(CH 3) C (O)} CF 3, -N = C (CH 3) OSi (CH 3) 3, -N = C (CF 3) OSi (CH 3) 3, -NHC (O) -OSi (CH ₃ ) ₃ , —NHC (O) —NH—Si (CH ₃ ) ₃ , imidazole ring (lower formula [4]), oxazolidinone ring (lower formula [5]), morpholine ring (lower formula [6]), − NH—C (O) —Si (CH ₃ ) ₃ , a monovalent functional group in which the element bonded to the silicon element is oxygen, a halogen group, a nitrile group, and —CO—NH—Si (CH ₃ ) ₃ At least one group selected from the group consisting of There, a is an integer of 1 to 3. ]

The nonaqueous solvent in the chemical solution for forming a water repellent protective film is composed of the solvent (I) and the solvent (II) in a mass ratio of 70:30 to 95: 5. 2. A chemical solution for forming a water-repellent protective film according to 1. The chemical solution for forming a water-repellent protective film according to claim 1 or 2, wherein the solvent (I) is a lactone solvent. The water-repellent protective film formation according to any one of claims 1 to 3, wherein the water-repellent protective film-forming chemical solution is maintained at a temperature of 10 ° C to 160 ° C. Chemical solution. The chemical solution for forming a water-repellent protective film according to any one of claims 1 to 4, wherein the silicon compound is a silicon compound represented by the following general formula [2].
R ² (CH ₃ ) ₂ SiX [2]
[In the formula [2], R ² is a monovalent hydrocarbon group having 4 to 18 carbon atoms in which some or all of the hydrogen elements may be replaced by halogen elements, and X is an isocyanate group, amino group, an alkylamino group, a dialkylamino group, an isothiocyanate group, an azide group, acetamido _{group, -N (CH 3) C (} O) CH 3, -N (CH 3) C (O) CF 3, -N = C _{(CH 3) OSi (CH 3} ) 3, -N = C (CF 3) OSi (CH 3) 3, -NHC (O) -OSi (CH 3) 3, -NHC (O) -NH-Si (CH ₃ ) ₃ , imidazole ring (lower formula [4]), oxazolidinone ring (lower formula [5]), morpholine ring (lower formula [6]), —NH—C (O) —Si (CH ₃ ) ₃ , silicon Monovalent functional group or halogen group in which the element binding element is oxygen Nitrile groups, and at least one group selected from the group consisting of _{-CO-NH-Si (CH 3} ) 3. ]

The chemical solution for forming a water-repellent protective film according to any one of claims 1 to 5, wherein the silicon compound is a silicon compound represented by the following general formula [3].
_{^{R 2 (CH 3) 2 Si}} -N (R 3) 2 [3]
[In the formula [3], R ² is a monovalent hydrocarbon group having 4 to 18 carbon atoms in which some or all of the hydrogen elements may be replaced by halogen elements, and R ³ is a methyl group, ethyl Group, propyl group, or butyl group. ] The chemical solution for forming a water-repellent protective film according to any one of claims 1 to 6, wherein a concentration of the silicon compound in the chemical solution for forming a water-repellent protective film is 0.1 to 4% by mass. . 8. The water repellent protective film-forming chemical solution according to claim 1, further comprising an acid in the water-repellent protective film-forming chemical solution. A water-repellent protective film-forming chemical solution kit for obtaining the water-repellent protective film-forming chemical solution according to claim 8, wherein the chemical solution kit comprises a silicon compound represented by the general formula [1] and a solvent (I ) And / or solvent (II), an acid, and a treatment liquid B having the solvent (I) and / or solvent (II). Chemical solution kit for formation. The chemical kit for forming a water-repellent protective film according to claim 9, wherein the solvent (I) is a lactone solvent. The chemical kit for forming a water-repellent protective film according to claim 9 or 10, wherein the silicon compound is a silicon compound represented by the general formula [2]. The chemical kit for forming a water-repellent protective film according to any one of claims 9 to 11, wherein the silicon compound is a silicon compound represented by the general formula [3]. In the cleaning of a wafer having a concavo-convex pattern on the surface and containing silicon oxide on at least the concave surface of the concavo-convex pattern, the steps shown below,
Cleaning the wafer surface with a cleaning liquid;
A water repellent protective film forming step of holding a water repellent protective film forming chemical in at least the concave portion of the wafer and forming a water repellent protective film on the concave surface;
A drying process to remove the liquid on the wafer surface;
A chemical solution for forming a water-repellent protective film according to any one of claims 1 to 8, comprising a water-repellent protective film removing step of removing the water-repellent protective film from the concave surface, A method for cleaning a wafer, comprising using a water-repellent protective film-forming chemical obtained from the water-repellent protective film-forming chemical liquid kit according to any one of claims 9 to 12. The water repellent protective film removing step is at least selected from irradiating the wafer surface with light, heating the wafer, irradiating the wafer surface with plasma, exposing the wafer surface to ozone, and corona discharging the wafer. The wafer cleaning method according to claim 13, wherein the wafer cleaning method is performed by one processing method.