JP2012015335A - Chemical for forming protective film, and cleaning method of wafer surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemical liquid for forming a protective film which reduces capillary force at an irregular pattern of a wafer in order to improve a cleaning step that tends to induce pattern collapse in a method of manufacturing a wafer where a fine irregular pattern is formed on the surface and silicon is contained at least partially in the irregular pattern.SOLUTION: The chemical liquid is used for forming a water-repellent protective film at least on the surface of recesses of an irregular pattern when cleaning a wafer having a fine irregular pattern containing silicon at least partially on the surface. The chemical contains 0.01-30 mass% of a silicon compound A represented by a general formula RSi(H)X, and an aprotic organic solvent.

Description

  The present invention relates to a substrate (wafer) cleaning technique for the purpose of improving the manufacturing yield of a device having a circuit pattern that is fine and has a high aspect ratio, particularly in the manufacture of semiconductor devices.

  In semiconductor devices for networks and digital home appliances, higher performance, higher functionality, and lower power consumption are required. For this reason, circuit patterns are being miniaturized, and accordingly, the particle size that causes a reduction in manufacturing yield is also miniaturized. As a result, a cleaning process intended to remove contaminants such as micronized particles is frequently used, and as a result, the cleaning process accounts for 30 to 40% of the entire semiconductor manufacturing process.

  On the other hand, in the conventional cleaning with the mixed ammonia cleaning agent, the damage to the wafer due to the basicity becomes a problem as the circuit pattern is miniaturized. For this reason, replacement with, for example, a dilute hydrofluoric acid-based cleaning agent with less damage is in progress.

  Thus, although the problem of damage to the wafer due to cleaning has been improved, the problem due to the increase in the aspect ratio of the pattern accompanying the miniaturization of the semiconductor device has become apparent. That is, after cleaning or rinsing, a phenomenon that the pattern collapses when the gas-liquid interface passes through the pattern causes a significant decrease in yield.

  This pattern collapse occurs when the wafer is pulled up from the cleaning liquid or the rinse liquid. This is said to be caused by a difference in residual liquid height between a portion where the aspect ratio of the pattern is high and a portion where the aspect ratio is low, thereby causing a difference in capillary force acting on the pattern. Note that the expression “falling” is sometimes referred to as “collapse”.

For this reason, if the capillary force is reduced, it can be expected that the difference in capillary force due to the difference in the residual liquid height will be reduced and the pattern collapse will be 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 (γ: surface tension, θ: contact angle, S: pattern dimension)

  Patent Document 1 discloses a technique for substituting the cleaning liquid from water to 2-propanol before passing through the gas-liquid interface as a technique for reducing γ and suppressing pattern collapse. However, while this method is effective for preventing pattern collapse, a solvent such as 2-propanol having a small γ tends to have a small normal contact angle and, as a result, tends to increase cos θ. Therefore, it is said that there is a limit, for example, the aspect ratio of the pattern that can be handled is 5 or less.

  Patent Document 2 discloses a technique for resist patterns as a technique for reducing cos θ to suppress pattern collapse. This method is a method of suppressing pattern collapse by setting cos θ close to 0 and reducing the capillary force to the limit by setting the contact angle near 90 °. However, since the disclosed technique is intended for a resist pattern, it modifies the resist itself, and can be finally removed together with the resist. Therefore, it is necessary to assume a method for removing the treatment agent after drying. Is not applicable to this purpose.

  Further, Patent Document 3 discloses that a wafer surface on which a concavo-convex pattern is formed by a film containing silicon is surface-modified by oxidation or the like, and a water-repellent protective film is formed on the surface using a water-soluble surfactant or silane coupling agent. A cleaning method is disclosed that reduces the capillary force and prevents the pattern from collapsing.

  In addition, as a technique for preventing pattern collapse of a semiconductor device, use of a critical fluid, use of liquid nitrogen, or the like has been proposed. However, although all have a certain effect, it is difficult to apply to a mass production process because the throughput is worse than the conventional cleaning process.

JP 2008-198958 A Japanese Patent Laid-Open No. 5-299336 Patent No. 4403202

  At the time of manufacturing a semiconductor device, the wafer surface is a surface having a fine uneven pattern. Capillary force of the concavo-convex pattern portion of the wafer during cleaning of a wafer having a fine concavo-convex pattern on the surface and at least a part of the concavo-convex pattern containing silicon (hereinafter referred to as “silicon wafer” or simply “wafer”) The water-repellent protective film (which may be referred to as “protective film”) is formed by the reaction of a silicon compound such as a silane coupling agent with an OH group introduced on the wafer surface.

  In order to shorten the cleaning process, it is necessary to efficiently form a protective film. However, the formation efficiency of the protective film depends on the contact probability between the OH group introduced on the wafer surface and the silicon compound. . Patent Document 3 discloses an example of using a silane coupling agent (undiluted). Although there is a suggestion that the silane coupling agent may be diluted with thinner, it is possible to promote the ester reaction of the silane coupling agent by increasing the liquid temperature or ultraviolet irradiation, that is, promoting the reaction with the OH group. Suggests the need.

  From the viewpoint of the chemical solution, the promotion of the reaction with the OH group is examined by increasing the amount of the silicon compound and increasing the contact probability between the OH group and the silicon compound. This leads to an increase in the amount of silicon compound in the chemical solution, and even if the silicon compound is diluted with thinner, it is easy to draw a conclusion that it should not be so diluted.

  The present invention relates to a chemical solution for forming a protective film for reducing a capillary force of a concave and convex pattern portion of a wafer for improving a cleaning process that easily induces pattern collapse, and in particular, a chemical solution that is effective in reducing the cost of the chemical solution, and An object of the present invention is to provide a method for cleaning a wafer surface using the chemical solution.

  The chemical solution for forming a protective film for reducing the capillary force of the uneven pattern portion of the wafer of the present invention (hereinafter referred to as “chemical solution for forming a protective film” or simply “chemical solution”) has a fine uneven pattern on the surface. A chemical solution for forming a water repellent protective film on at least the concave surface of the concavo-convex pattern at the time of cleaning a wafer in which at least a part of the pattern contains silicon, and the silicon compound A represented by the following general formula [1] is 0 A protective film-forming chemical solution comprising 0.01 to 30% by mass and an aprotic organic solvent.

Here, R ¹ is each independently a monovalent organic group containing a hydrocarbon group having 1 to 18 carbon atoms and a monovalent organic group containing a fluoroalkyl chain having 1 to 8 carbon atoms. X is at least one group selected from: a monovalent organic group in which the element bonded to Si is nitrogen, a monovalent organic group in which the element bonded to Si is oxygen, and , At least one group selected from halogen groups, a is an integer of 1 to 3, b is an integer of 0 to 2, and the sum of a and b is 1 to 3.

  The technical idea of the chemical solution of the present invention in which the aprotic organic solvent occupies the main component in the chemical solution is that the content of the silicon compound A forming the protective film is as small as 0.01 to 30% by mass. Surprisingly, it is based on a new finding that the formation efficiency of the protective film was good.

  Further, the silicon compound A may show basicity or acidity. When X is a monovalent organic group in which the element bonded to Si is nitrogen, it exhibits basicity. For example, in the case of hexamethyldisilazane, the pH is 10 at 100%. When X is a halogen group, it exhibits acidity. For example, in the case of trimethylchlorosilane, the pH becomes 0 in a state of 100%. Since the chemical solution is used for semiconductor cleaning, it needs to be purified for high purity. However, even if the basicity and acidity of the silicon compound A are high, the chemical solution of the present invention Since the silicon compound A was diluted to 30% or less, it was found that the basicity or acidity of the chemical solution was relaxed and effects such as easy purification by ion exchange were produced. . This will succeed in reducing the cost of the chemical solution. Moreover, the suitable chemical | medical solution of this invention occupies the quantity used as the main component of a chemical | medical solution with content of an aprotic organic solvent 50-99.99 mass%, and it is from a viewpoint that the basicity or acidity of a chemical | medical solution eases. It becomes more preferable.

  In the present specification, a pH value may be used as an index indicating the basicity or acidity of a chemical solution. Here, pH of a chemical | medical solution can be measured using a pH test paper (WR by ADVANTEC) at 25 degreeC, for example. For example, in the case of hexamethyldisilazane, the pH is 9 when the propylene glycol monomethyl ether acetate is used as a diluent solvent and the amount of hexamethyldisilazane is 20 to 30% by mass.

  In the chemical solution of the present invention, the content of the silicon compound A is preferably 0.01 to 30% by mass. If the content is less than 0.01% by mass, the effect of preventing the collapse of the concave / convex pattern becomes insufficient, and if it exceeds 30% by mass, the effect of preventing the collapse of the concave / convex pattern does not increase so much and the material cost increases. More preferably, it is 0.05-25 mass%, More preferably, it is 0.1-20 mass%.

  In the chemical solution of the present invention, the aprotic organic solvent preferably has a solubility in 100 parts by mass of water of 5 parts by mass or more. In this case, since the chemical solution has good compatibility with water, at the time of cleaning a wafer having a fine concavo-convex pattern on the surface and at least a part of the concavo-convex pattern containing silicon, water is present in the concave portions of the concavo-convex pattern. This water and chemical solution can be replaced in the stored state. Furthermore, the chemical solution and water can be replaced while the chemical solution is stored in the recess. Even if the silicon compound A does not have good water compatibility, the replacement step with the recesses during cleaning can be compatible with either “water → alcohol → chemical solution → alcohol → water” or “water → chemical solution → water”. Can do. If the content of the aprotic organic solvent in the chemical solution is small, the replacement of the chemical solution with water is slowed, resulting in a low throughput or an increase in the amount of chemical solution used, which is not preferable. In addition, when the content of the silicon compound A is reduced as the content is increased, the effect of preventing the concave / convex pattern from being collapsed becomes insufficient. For this reason, it is preferable that content of the aprotic organic solvent in the said chemical | medical solution is 50-99.99 mass%, More preferably, it is 60-99.95 mass%, More preferably, it is 65-99.9 mass%. It is.

  In addition, if the solubility of water in the aprotic organic solvent is reduced, the substitution between the chemical solution and water is delayed, resulting in a low throughput or an increase in the amount of chemical solution used, which is not preferable. For this reason, it is preferable that the solubility of water with respect to an aprotic organic solvent is 5 mass parts or more with respect to 100 mass parts of water, More preferably, it is 20 mass parts or more.

R ^{1 in the} general formula [1] reduces the surface energy of the protective film, and interacts between water or other liquid and the surface of the protective film (interface), for example, hydrogen bonding, intermolecular force. Etc. 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. Thereby, the contact angle of the liquid with respect to the article | item surface can be enlarged.

  The protective film is formed by chemically bonding X in the general formula [1] with Si of the silicon wafer. Therefore, when the cleaning liquid is removed from the recess of the silicon wafer, that is, when it is dried, since the protective film is formed on the surface of the recess, the capillary force on the surface of the recess is reduced, and pattern collapse occurs. It becomes difficult.

  Moreover, it is preferable that X in the silicon compound A is a monovalent organic group in which the element bonded to Si is nitrogen, and the chemical solution contains the acid A. This is preferable because the reaction between the silicon compound A and Si on the silicon wafer is fast and the water-repellent protective film can be formed in a short time.

  In addition, when the acid A is a Bronsted acid, the acid may react with the silicon compound A to reduce the silicon compound A or reduce the reactivity of the silicon compound A. For this reason, the acid A is preferably a Lewis acid.

  Moreover, it is preferable that the said chemical | medical solution has a boiling point in 70-220 degreeC. The boiling point within this range is particularly preferable when the chemical solution is supplied to the wafer surface having a fine concavo-convex pattern by the centrifugal force of the rotation of the wafer. A low boiling point is not preferable because the chemical solution is likely to dry before the chemical solution wets and spreads over the entire wafer surface. On the other hand, when the boiling point is high, the viscosity of the chemical solution is increased, and therefore, the chemical solution is difficult to uniformly spread over the entire wafer surface, which is not preferable. For this reason, the said boiling point is 70-220 degreeC, Especially 75-200 degreeC is preferable.

  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.

  In the present invention, when the cleaning liquid is removed from the recess, that is, when dried, the protective film is formed on at least the recess surface of the recess / protrusion pattern, so that the capillary force on the recess surface is reduced and the pattern collapses. Is less likely to occur.

  The chemical solution for forming a protective film of the present invention is used by replacing the cleaning solution with the chemical solution in the step of cleaning the wafer on which the uneven pattern is formed. Further, the replaced chemical liquid may be replaced with another cleaning liquid.

  As described above, the cleaning liquid is replaced with the protective film forming chemical solution, and the protective film is formed on at least the concave surface of the concave / convex pattern while the chemical liquid is held on at least the concave surface of the concave / convex pattern. The protective film of the present invention does not necessarily have to be formed continuously, and does not necessarily have to be formed uniformly. However, since it can impart better water repellency, it can be applied continuously and uniformly. More preferably, it is formed.

  Since the protective film formed by the protective film-forming chemical solution of the present invention exhibits an excellent pattern collapse preventing effect, the cleaning step in the method of manufacturing a wafer having a fine concavo-convex pattern on the surface is possible when the chemical solution is used. Is improved without lowering. Therefore, the method for producing a wafer having a fine concavo-convex pattern on the surface, which is carried out using the chemical solution for forming a protective film of the present invention, has high productivity.

  The chemical solution for forming a protective film according to the present invention can cope with a concavo-convex pattern having an aspect ratio of, for example, 7 or more which is expected to become higher in the future, and can reduce the cost of production of higher-density semiconductor devices. . In addition, the conventional apparatus can be applied without significant change, and as a result, can be applied to the manufacture of various semiconductor devices.

It is a figure which shows the schematic diagram when the wafer 1 made into the surface which has the fine uneven | corrugated pattern 2 on the surface is perspective. FIG. 2 shows a part of the a-a ′ cross section in FIG. 1. The schematic diagram of the state in which the recessed part 4 hold | maintained the protective film formation chemical | medical solution 8 at the washing | cleaning process is shown. It is a figure which shows the schematic diagram of the state by which the washing | cleaning liquid and / or the chemical | medical solution were hold | maintained at the recessed part 4 in which the water-repellent protective film was formed.

A suitable cleaning method for a wafer having a fine concavo-convex pattern on the surface and containing at least part of the concavo-convex pattern using the chemical solution for forming a protective film of the present invention,
(Step 1) A step of making the wafer surface a surface having a fine concavo-convex pattern, then subjecting the surface to an aqueous cleaning solution, and holding the aqueous cleaning solution on at least the concave surface of the concavo-convex pattern;
(Step 2) A step of replacing the aqueous cleaning liquid held on at least the concave surface of the concavo-convex pattern with a cleaning liquid A different from the aqueous cleaning liquid,
(Step 3) Replacing the cleaning liquid A with a protective film-forming chemical solution, and holding the chemical solution on at least the concave surface of the concave-convex pattern;
(Step 4) A step of removing liquid from the surface of the concavo-convex pattern by drying,
(Step 5) It includes a step of removing the water-repellent protective film by performing at least one treatment selected from irradiating the wafer surface with light, heating the wafer, and exposing the wafer to ozone.

  Further, after the step (Step 3) of holding the chemical solution for forming the protective film on at least the concave surface of the concavo-convex pattern, the chemical solution held on at least the concave surface of the concavo-convex pattern was replaced with a cleaning liquid B different from the chemical solution. Later, the process may be shifted to a step of removing the liquid from the surface of the concavo-convex pattern by drying (step 4). In addition, after the replacement with the cleaning liquid B, an aqueous cleaning liquid composed of an aqueous solution is held on at least the concave surface of the concave / convex pattern, and then the process may be shifted to a step of removing the liquid from the concave / convex pattern surface by drying (step 4). . In addition, the liquid removed in the said (process 4) is a washing | cleaning liquid and / or a chemical | medical solution.

  In the present invention, when the aprotic organic solvent contained in the protective film-forming chemical solution has a solubility of 5 parts by mass or more with respect to 100 parts by mass of water, the protective film-forming chemical solution can be replaced with an aqueous cleaning liquid. Therefore, the replacement with the cleaning liquid A and the replacement with the cleaning liquid B can be omitted.

  In the present invention, the cleaning method of the wafer is not particularly limited as long as the chemical liquid or the cleaning liquid can be held on at least the concave surface of the concave / convex pattern of the wafer. As a wafer cleaning method, a wafer cleaning method represented by spin cleaning in which a wafer is cleaned one by one by supplying liquid to the vicinity of the rotation center while rotating the wafer while holding the wafer substantially horizontal, or a plurality of cleaning methods in the cleaning tank. One example is a batch system in which a single wafer is immersed and washed. The form of the chemical solution or cleaning liquid when supplying the chemical solution or cleaning liquid to at least the concave surface of the concave / convex pattern of the wafer is not particularly limited as long as it becomes liquid when held on the concave surface, for example, , Liquid, vapor, etc.

  The silicon compound A in the chemical solution is preferably a compound represented by the following general formula [1].

Here, R ¹ is each independently a monovalent organic group containing a hydrocarbon group having 1 to 18 carbon atoms and a monovalent organic group containing a fluoroalkyl chain having 1 to 8 carbon atoms. X is at least one group selected from: a monovalent organic group in which the element bonded to Si is nitrogen, a monovalent organic group in which the element bonded to Si is oxygen, and , At least one group selected from halogen groups, a is an integer of 1 to 3, b is an integer of 0 to 2, and the sum of a and b is 1 to 3.

In the general formula [1], the monovalent organic group in which the element bonded to Si as X is nitrogen or oxygen includes not only hydrogen, carbon, nitrogen, and oxygen, but also silicon, sulfur, and halogen elements. May be. Examples of the monovalent organic group in which the element bonded to Si is nitrogen include an isocyanate group, an amino group, a dialkylamino group, an isothiocyanate group, an azide group, an acetamide 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 [2]), oxazolidinone ring (lower formula [3]), morpholine ring (lower formula [4] ), —NH—C (O) —Si (CH ₃ ) ₃ , —N (H) _{2 -c} (Si (H) _d R ² _3-d ) _c (R ² represents a part or all of hydrogen A monovalent hydrocarbon group having 1 to 18 carbon atoms which may be replaced by fluorine, c is 1 Et 2, d is like an integer) of 0-2. In addition, as the monovalent organic group of oxygen that is bonded to Si as X, there are those bonded to Si by Si—O—C or Si—O—S, and those bonded by Si—O—C. examples include alkoxy _{groups, -OC (CH 3) = CHCOCH} 3, -OC (CH 3) = N-Si (CH 3) 3, -OC (CF 3) = N-Si (CH 3) 3, - OC (O) —R ³ (R ³ is an alkyl group having 1 to 8 carbon atoms in which some or all of the hydrogen atoms may be replaced by fluorine atoms) and the like are bonded with Si—O—S. ^{_{examples, -OS (O 2) -R 2}} (R 2 is partially or carbon atoms, which may have all hydrogens replaced by fluorine monovalent hydrocarbon group having 1 to 18), and the like It is done. Furthermore, examples of the halogen group as X include a chloro group and a bromo group. In such a silicon compound A, the reactive site reacts quickly with silanol groups on the surface of the concave / convex pattern of the silicon wafer, and the silicon compound A chemically bonds with Si of the silicon wafer through a siloxane bond, Since the wafer surface can be covered with the hydrophobic R ¹ group, the capillary force on the concave surface of the wafer can be reduced in a short time.

  Moreover, it is more preferable that the number of X of the silicon compound A represented by 4-ab in the general formula [1] is 1 because the protective film can be formed uniformly.

R ¹ in the general formula [1] is independently selected from C _m H _{2m + 1} (m = 1 to 18) and C _n F _{2n + 1} CH ₂ CH ₂ (n = 1 to 8). One group is more preferable because when the protective film is formed on the surface of the concavo-convex pattern, the wettability of the surface can be further reduced, that is, excellent water repellency can be imparted to the surface. Moreover, it is more preferable that m and n are 1 to 8 because a protective film can be formed on the surface of the concavo-convex pattern in a short time.

Examples of the silicon compound A represented by the general formula [1] include CH ₃ Si (NH ₂ ) ₃ , C ₂ H ₅ Si (NH ₂ ) ₃ , C ₃ H ₇ Si (NH ₂ ) ₃ , C ₄ H ₉ Si (NH ₂ ) ₃ , C ₅ H ₁₁ Si (NH ₂ ) ₃ , C ₆ H ₁₃ Si (NH ₂ ) ₃ , C ₇ H ₁₅ Si (NH ₂ ) ₃ , C ₈ H ₁₇ Si (NH ₂ ) ₂ ) ₃ , C ₉ H ₁₉ Si (NH ₂ ) ₃ , C ₁₀ H ₂₁ Si (NH ₂ ) ₃ , C ₁₁ H ₂₃ Si (NH ₂ ) ₃ , C ₁₂ H ₂₅ Si (NH ₂ ) ₃ , C ₁₃ H ₂₇ Si (NH ₂ ) ₃ , C ₁₄ H ₂₉ Si (NH ₂ ) ₃ , C ₁₅ H ₃₁ Si (NH ₂ ) ₃ , C ₁₆ H ₃₃ Si (NH ₂ ) ₃ , C ₁₇ H ₃₅ Si (NH ₂₎ ) ₃ , C ₁₈ H ₃₇ Si (NH ₂ ) ₃ , ( _{CH 3) 2 Si (NH 2} ) 2, C 2 H 5 Si (CH 3) (NH 2) 2, (C 2 H 5) 2 Si (NH 2) 2, C 3 H 7 Si (CH 3) ( _{NH 2) 2, (C 3} H 7) 2 Si (NH 2) 2, C 4 H 9 Si (CH 3) (NH 2) 2, (C 4 H 9) 2 Si (NH 2) 2, C 5 H ₁₁ Si (CH ₃ ) (NH ₂ ) ₂ , C ₆ H ₁₃ Si (CH ₃ ) (NH ₂ ) ₂ , C ₇ H ₁₅ Si (CH ₃ ) (NH ₂ ) ₂ , C ₈ H ₁₇ Si (CH ₃ ) (NH ₂ ) ₂ , C ₉ H ₁₉ Si (CH ₃ ) (NH ₂ ) ₂ , C ₁₀ H ₂₁ Si (CH ₃ ) (NH ₂ ) ₂ , C ₁₁ H ₂₃ Si (CH ₃ ) (NH ₂ ) _{) 2, C 12 H 25 Si} (CH 3) (NH 2) 2, C 13 H 27 Si (CH _{) (NH 2) 2, C} 14 H 29 Si (CH 3) (NH 2) 2, C 15 H 31 Si (CH 3) (NH 2) 2, C 16 H 33 Si (CH 3) (NH 2) ₂ , C ₁₇ H ₃₅ Si (CH ₃ ) (NH ₂ ) ₂ , C ₁₈ H ₃₇ Si (CH ₃ ) (NH ₂ ) ₂ , (CH ₃ ) ₃ SiNH ₂ , C ₂ H ₅ Si (CH ₃ ) _{2 NH 2, (C 2 H 5} ) 2 Si (CH 3) NH 2, (C 2 H 5) 3 SiNH 2, C 3 H 7 Si (CH 3) 2 NH 2, (C 3 H 7) 2 Si ( CH ₃ ) NH ₂ , (C ₃ H ₇ ) ₃ SiNH ₂ , C ₄ H ₉ Si (CH ₃ ) ₂ NH ₂ , (C ₄ H ₉ ) ₃ SiNH ₂ , C ₅ H ₁₁ Si (CH ₃ ) ₂ NH ₂ , C ₆ H ₁₃ Si (CH ₃ ) ₂ NH ₂ , C ₇ H ₁₅ Si (CH ₃ ) ₂ NH ₂ , C ₈ H ₁₇ Si (CH ₃ ) ₂ NH ₂ , C ₉ H ₁₉ Si (CH ₃ ) ₂ NH ₂ , C ₁₀ H ₂₁ Si (CH ₃ ) ₂ NH ₂ , C _{11 H 23 Si (CH 3)} 2 NH 2, C 12 H 25 Si (CH 3) 2 NH 2, C 13 H 27 Si (CH 3) 2 NH 2, C 14 H 29 Si (CH 3) 2 NH 2 , C ₁₅ H ₃₁ Si (CH ₃ ) ₂ NH ₂ , C ₁₆ H ₃₃ Si (CH ₃ ) ₂ NH ₂ , C ₁₇ H ₃₅ Si (CH ₃ ) ₂ NH ₂ , C ₁₈ H ₃₇ Si (CH ₃ ) _{2 NH 2, (CH 3) 2} Si (H) NH 2, CH 3 Si (H) 2 NH 2, (C 2 H 5) 2 Si (H) NH 2, C 2 H 5 Si (H) 2 NH 2 , C ₂ H ₅ Si (CH ₃ ) (H) N _{H 2, (C 3 H 7} ) 2 Si (H) NH 2, C 3 H 7 Si (H) 2 NH 2, CF 3 CH 2 CH 2 Si (NH 2) 3, C 2 F 5 CH 2 CH 2 Si (NH ₂ ) ₃ , C ₃ F ₇ CH ₂ CH ₂ Si (NH ₂ ) ₃ , C ₄ F ₉ CH ₂ CH ₂ Si (NH ₂ ) ₃ , C ₅ F ₁₁ CH ₂ CH ₂ Si (NH ₂ ) ₃ , C ₆ F ₁₃ CH ₂ CH ₂ Si (NH ₂ ) ₃ , C ₇ F ₁₅ CH ₂ CH ₂ Si (NH ₂ ) ₃ , C ₈ F ₁₇ CH ₂ CH ₂ Si (NH ₂ ) ₃ , CF ₃ CH _{2 CH 2 Si (CH 3)} (NH 2) 2, C 2 F 5 CH 2 CH 2 Si (CH 3) (NH 2) 2, C 3 F 7 CH 2 CH 2 Si (CH 3) (NH 2) _{2, C 4 F 9 CH 2} CH 2 Si (CH 3) (NH _{2) 2, C 5 F 11} CH 2 CH 2 Si (CH 3) (NH 2) 2, C 6 F 13 CH 2 CH 2 Si (CH 3) (NH 2) 2, C 7 F 15 CH 2 CH 2 _{Si (CH 3) (NH 2} ) 2, C 8 F 17 CH 2 CH 2 Si (CH 3) (NH 2) 2, CF 3 CH 2 CH 2 Si (CH 3) 2 NH 2, C 2 F 5 CH ₂ CH ₂ Si (CH ₃ ) ₂ NH ₂ , C ₃ F ₇ CH ₂ CH ₂ Si (CH ₃ ) ₂ NH ₂ , C ₄ F ₉ CH ₂ CH ₂ Si (CH ₃ ) ₂ NH ₂ , C ₅ F _{11 CH 2 CH 2 Si (CH 3} ) 2 NH 2, C 6 F 13 CH 2 CH 2 Si (CH 3) 2 NH 2, C 7 F 15 CH 2 CH 2 Si (CH 3) 2 NH 2, C 8 F ₁₇ CH ₂ CH ₂ Si (CH ₃ ) An aminosilane such as ₂ NH ₂ , CF ₃ CH ₂ CH ₂ Si (CH ₃ ) (H) NH ₂ , or an amino group (—NH ₂ group) of the aminosilane is represented by —N═C═O, —N (CH _{3) 2, -N (C 2} H 5) 2, -N = C = S, -N 3, -NHC (O) CH 3, -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, an imidazole ring, an oxazolidinone ring, morpholine _{ring, -NH-C (O) -Si} (CH 3) 3, -N (H) 2-c ( ^{_{Si (H) d R 2 3}} -d) c (R 2 is not a part or all of the hydrogen replaced by fluorine Also a good monovalent hydrocarbon group having 1 to 18 carbon, c is 1 or 2, d is 0 to 2 integer), an alkoxy _{group, -OC (CH 3) = CHCOCH} 3, -OC (CH 3) = N-Si (CH ₃ ) ₃ , -OC (CF ₃ ) = N-Si (CH ₃ ) ₃ , -OS (O ₂ ) -R ² (R ² is a part or all of hydrogen replaced with fluorine. And a monovalent hydrocarbon group having 1 to 18 carbon atoms), —OC (O) —R ³ (R ³ is a carbon number in which some or all of the hydrogen atoms may be replaced by fluorine atoms) Are alkyl groups of 1 to 8), chloro groups, bromo groups, and the like.

Among these, X of the silicon compound A on the left side of the general formula [1] is —N (CH ₃ ) ₂ , —NH ₂ , —N (C ₂ H ₅ ) ₂ , —N (CH ₃ ) C (O ) CH ₃ , —N (CH ₃ ) C (O) CF ₃ , —NHC (O) —NH—Si (CH ₃ ) ₃ , imidazole ring, —NH—C (O) —Si (CH ₃ ) ₃ , _{-N (H) 2-r (} Si (H) j R 8 3-s) r (R 8 is a monovalent partially or carbon atoms, which may have all hydrogens replaced by fluorine 1-8 In which r is 1 or 2, and s is an integer of 0 to 2.

  The chemical solution preferably contains 50 to 99.99% by mass of an aprotic organic solvent. Here, the aprotic organic solvent preferably has a solubility in 100 parts by mass of water of 5 parts by mass or more. In addition, the solubility with respect to water points out the value in 20 degreeC. Examples of such solvents include ethers, ketones, sulfoxide solvents, polyhydric alcohol derivatives having no OH group, and nitrogen-containing compound solvents. Examples of the ethers include tetrahydrofuran, dioxane, etc., examples of the ketones include acetylacetone, acetone, cyclohexanone, etc., examples of the sulfoxide solvents include dimethyl sulfoxide, etc. Examples of alcohol derivatives having no OH group include diethylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol diacetate, ethylene glycol diacetate, ethylene Examples of nitrogen-containing compound solvents such as glycol dimethyl ether include N, N-dimethylform Amides, N- methyl-2-pyrrolidone, pyridine, and the like. Among these, diethylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol diacetate, ethylene glycol diacetate, ethylene glycol dimethyl ether, and cyclohexanone are preferable.

  As described above, the aprotic organic solvent preferably has a solubility with respect to 100 parts by mass of water of 5 parts by mass or more, but the chemical solution has an aprotic with a solubility with respect to 100 parts by mass of water of 5 parts by mass or more. An organic solvent other than the organic solvent may be contained. Examples of such organic solvents include hydrocarbons, esters, ethers, ketones, halogen-containing solvents, sulfoxide solvents, alcohols, polyhydric alcohol derivatives, nitrogen-containing compound solvents, and the like. Among these, aprotic hydrocarbons, esters, ethers, ketones, halogen-containing solvents, sulfoxide solvents, and polyhydric alcohol derivatives having no OH group are preferably used. Examples of the hydrocarbons include toluene, benzene, xylene, hexane, heptane, and octane. Examples of the esters include ethyl acetate, propyl acetate, butyl acetate, and ethyl acetoacetate, and the ether. Examples of such classes include diethyl ether, dipropyl ether, and dibutyl ether. Examples of the ketones include methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, cyclohexanone, and isophorone. Examples of the halogen-containing solvent include As perfluorocarbons such as perfluorooctane, perfluorononane, perfluorocyclopentane, perfluorocyclohexane, hexafluorobenzene, 1,1,1,3,3-pentafluorobutane, octafluorocyclopentane, , 3-dihydrodecafluoropentane, Zeolora H (manufactured by Nippon Zeon Co., Ltd.), methyl perfluoroisobutyl ether, methyl perfluorobutyl ether, ethyl perfluorobutyl ether, ethyl perfluoroisobutyl ether, Asahiklin AE-3000 (Asahi Glass) ), Novec HFE-7100, Novec HFE-7200, Novec7300, and Novec7600 (all manufactured by 3M), chlorocarbons such as tetrachloromethane, hydrochlorocarbons such as chloroform, and chlorofluorocarbons such as dichlorodifluoromethane. 1,1-dichloro-2,2,3,3,3-pentafluoropropane, 1,3-dichloro-1,1,2,2,3- There are hydrochlorofluorocarbons such as interfluoropropane, 1-chloro-3,3,3-trifluoropropene, 1,2-dichloro-3,3,3-trifluoropropene, perfluoroether, perfluoropolyether, etc. Examples of the polyhydric alcohol derivative having no OH group include ethylene glycol dibutyl ether. The chemical solution may not contain an aprotic organic solvent having a solubility in 100 parts by mass of water of 5 parts by mass or more.

  Moreover, it is preferable that the said chemical | medical solution has a boiling point in 70-220 degreeC. The boiling point within this range is particularly preferable when the chemical solution is supplied to the wafer surface having a fine concavo-convex pattern by the centrifugal force of the rotation of the wafer.

  Moreover, it is preferable that X in the silicon compound A is a monovalent organic group in which the element bonded to Si is nitrogen, and the chemical solution contains the acid A. This is preferable because the reaction between the silicon compound A and Si on the silicon wafer is fast and the water-repellent protective film can be formed in a short time.

  The concentration of the acid A is preferably 0.01 to 50% by mass with respect to 100% by mass of the total amount of the silicon compound A. If the addition amount is small, the catalytic effect of the acid is lowered, which is not preferable. Even if it is excessively added, the catalytic effect is not improved. On the contrary, there is a concern that the wafer surface may be eroded or remain as impurities on the wafer. For this reason, it is especially preferable that the density | concentration of the acid A is 0.02-40 mass% with respect to 100 mass% of total amounts of the said silicon compound A, Furthermore, 0.05-30 mass%.

  If the acid A contains water, the water contained in the chemical solution increases, and the protective film is hardly formed. For this reason, the acid A is preferably as the water content is small, and the preferable water content is 35% by mass or less, particularly preferably 10% by mass, and further preferably 5% by mass or less. Ideally, it is close to 0% by mass.

  Examples of the acid A include inorganic acids and organic acids. Examples of inorganic acids with low water content include hydrogen halides, sulfuric acid, perchloric acid, phosphoric acid, etc. Examples of organic acids include those in which some or all of the hydrogen is replaced by fluorine atoms, etc. There are good alkane sulfonic acids, carboxylic acids, benzene sulfonic acids, p-toluene sulfonic acids and the like.

  As the acid, a Lewis acid can also be used. The definition of Lewis acid is described in, for example, “Physical and Chemical Dictionary (Fifth Edition)”. Examples of Lewis acids include acid anhydrides, boron compounds, and silicon compounds. Examples of acid anhydrides include anhydrides in which some or all of hydrogen such as trifluoromethanesulfonic anhydride may be substituted with fluorine atoms or the like. Examples of boron compounds such as alkanesulfonic acid, acetic anhydride, trifluoroacetic anhydride, pentafluoropropionic anhydride, etc., such as carboxylic anhydrides in which part or all of hydrogen may be substituted with fluorine atoms, etc. include alkylboric acid Examples of silicon compounds such as esters, arylborates, tris (trifluoroacetoxy) borane, trialkoxyboroxine, trifluoroboron, etc., chlorosilane, part or all of hydrogen may be substituted with fluorine atoms, etc. Alkylsilylalkylsulfonates, some or all of the hydrogen Substituted with atom etc., and the like alkyl silyl esters. In addition, when the said silicon compound is used, at least one part of the said protective film may be formed with this silicon compound.

  When the acid A is a Bronsted acid, the acid reacts with the silicon compound A to reduce the silicon compound A or reduce the reactivity of the silicon compound A. It is preferable to contain a Lewis acid, and in particular, an acid anhydride and a silicon compound α represented by the following general formula [5] are preferable.

Here, R ⁴ is each independently a monovalent organic group containing a hydrocarbon group having 1 to 18 carbon atoms and a monovalent organic group containing a fluoroalkyl chain having 1 to 8 carbon atoms. And Y is independently of each other a halogen group, —O—S (O ₂ ) —R ′, and —O—C (O) —R ′ (R ′ is independently selected from It is at least one group selected from a monovalent hydrocarbon group having 1 to 8 carbon atoms in which some or all of hydrogen may be replaced by fluorine. Moreover, e is an integer of 1-3, f is an integer of 0-2, and the sum total of e and f is 1-3.

Examples of the acid A include CH ₃ SiCl ₃ , C ₂ H ₅ SiCl ₃ , C ₃ H ₇ SiCl ₃ , C ₄ H ₉ SiCl ₃ , C ₅ H ₁₁ SiCl ₃ , C ₆ H ₁₃ SiCl ₃ , and 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 , (CH ₃ ) ₂ SiCl ₂ , C ₂ H ₅ Si (CH ₃ ) Cl ₂ , (C ₂ H ₅ ) ₂ SiCl ₂ , C ₃ H ₇ Si (CH ₃ ) Cl ₂ , (C ₃ H ₇ ) ₂ SiCl ₂ , C ₄ H ₉ Si (CH ₃ ) Cl ₂ , (C ₄ H ₉ ) ₂ SiCl ₂ , C ₅ H ₁₁ Si (CH ₃ ) Cl ₂ , C ₆ H ₁₃ Si (CH ₃ ) Cl ₂ , C ₇ H ₁₅ Si ( CH ₃ ) Cl ₂ , C ₈ H ₁₇ Si (CH ₃ ) Cl ₂ , C ₉ H ₁₉ Si (CH ₃ ) Cl ₂ , C ₁₀ H ₂₁ Si (CH ₃ ) Cl ₂ , C ₁₁ H ₂₃ Si (CH ₃ ) Cl ₂ , C ₁₂ H ₂₅ Si (CH ₃ ) Cl ₂ , C ₁₃ H ₂₇ Si (CH ₃ ) Cl ₂ , C ₁₄ H ₂₉ Si (CH ₃ ) Cl ₂ , C ₁₅ H ₃₁ Si (CH ₃ ) Cl ₂ , C ₁₆ H ₃₃ Si (CH ₃ ) Cl ₂ , C ₁₇ H ₃₅ Si (CH ₃ ) Cl ₂ , C ₁₈ H ₃₇ Si (CH ₃ ) Cl ₂ , (CH ₃ ) ₃ SiCl, C ₂ H ₅ Si (CH ₃ ) ₂ Cl, (C ₂ H ₅ ) ₂ Si (CH ₃ ) Cl, (C ₂ H ₅ ) ₃ SiCl, C ₃ H ₇ Si (CH ₃ ) ₂ Cl, (C ₃ H ₇ ) ₂ Si (CH ₃ ) Cl, (C ₃ H ₇ ) ₃ SiCl, C ₄ H ₉ Si (CH ₃ ) ₂ Cl, (C ₄ H ₉ ) ₃ SiCl, C ₅ H ₁₁ Si (CH ₃ ) ₂ Cl, C ₆ H ₁₃ Si (CH ₃ ) ₂ Cl C ₇ H ₁₅ Si (CH ₃ ) ₂ Cl, C ₈ H ₁₇ Si (CH ₃ ) ₂ Cl, C ₉ H ₁₉ Si (CH ₃ ) ₂ Cl, C ₁₀ H ₂₁ Si (CH ₃ ) ₂ Cl, C _{11 H 23 Si (CH 3)} 2 Cl, C 12 H 25 Si (CH 3) 2 Cl, C 13 H 27 Si (CH 3) 2 Cl, C 14 H 29 Si (CH 3) 2 Cl, C 15 H ₃₁ Si (CH ₃ ) ₂ Cl, C ₁₆ H ₃₃ Si (CH ₃ ) ₂ Cl, C ₁₇ H ₃₅ Si (CH ₃ ) ₂ Cl, C ₁₈ H ₃₇ Si (CH ₃ ) ₂ Cl, (CH ₃ ) ₂ Si (H) Cl, CH ₃ Si (H) ₂ Cl, (C ₂ H ₅ ) ₂ Si (H) Cl, C ₂ H ₅ Si (H) ₂ Cl, C ₂ H ₅ Si (CH ₃ ) (H) Cl, (C ₃ H ₇ ) ₂ Si (H _{) Cl, C 3 H 7 Si} (H) 2 Cl, CF 3 CH 2 CH 2 SiCl 3, C 2 F 5 CH 2 CH 2 SiCl 3, C 3 F 7 CH 2 CH 2 SiCl 3, C 4 F 9 CH ₂ CH ₂ SiCl ₃ , C ₅ F ₁₁ CH ₂ CH ₂ SiCl ₃ , C ₆ F ₁₃ CH ₂ CH ₂ SiCl ₃ , C ₇ F ₁₅ CH ₂ CH ₂ SiCl ₃ , C ₈ F ₁₇ CH ₂ CH ₂ SiCl ₃ , CF ₃ CH ₂ CH ₂ Si (CH ₃ ) Cl ₂ , C ₂ F ₅ CH ₂ CH ₂ Si (CH ₃ ) Cl ₂ , C ₃ F ₇ CH ₂ CH ₂ Si (CH ₃ ) Cl ₂ , C ₄ F ₉ CH ₂ CH ₂ Si (CH _{3) Cl 2, C 5 F} 11 CH 2 CH 2 Si (CH 3) Cl 2, C 6 F 13 CH 2 CH 2 Si (CH 3) Cl 2, C 7 F 15 CH 2 CH 2 Si (CH 3) _{Cl 2, C 8 F 17 CH} 2 CH 2 Si (CH 3) Cl 2, CF 3 CH 2 CH 2 Si (CH 3) 2 Cl, C 2 F 5 CH 2 CH 2 Si (CH 3) 2 Cl, C _{3 F 7 CH 2 CH 2 Si} (CH 3) 2 Cl, C 4 F 9 CH 2 CH 2 Si (CH 3) 2 Cl, C 5 F 11 CH 2 CH 2 Si (CH 3) 2 Cl, C 6 F ₁₃ CH ₂ CH ₂ Si (CH _{) 2 Cl, C 7 F 15} CH 2 CH 2 Si (CH 3) 2 Cl, C 8 F 17 CH 2 CH 2 Si (CH 3) 2 Cl, CF 3 CH 2 CH 2 Si (CH 3) (H) Chlorosilane such as Cl, or the chloro group of the chlorosilane is replaced with another halogen group, —O—S (O ₂ ) —R ′, or —O—C (O) —R ′ (R ′ is part or all of Or a monovalent hydrocarbon group having 1 to 8 carbon atoms, which may be replaced by fluorine, and the like.

R— of the —O—S (O ₂ ) —R ′ group and the —O—C (O) —R ′ group that may be the —Y group of the general formula [5] is, for example, —CH _{3, -C 2 H 5, -C} 3 H 7, -C 4 H 9, -C 6 H 5, -C 6 H 4 -CH 3, -CF 3, -C 2 H 4 -CF 3, -C _{2 F 5, -C 6 F 5} , and the like -C ₆ F 4 -CH _3.

Among these, it is more preferable that the —Y group is a chloro group, —OC (O) —CF ₃ , —OS (O ₂ ) —CF ₃ because a protective film can be formed on the surface of the concavo-convex pattern in a short time.

  The acid A may be obtained by a reaction. For example, it may be obtained by reacting silicon compound B and acid B as represented by the following general formula [6].

^{_{Wherein, R 5 g (H) h}} Si-Z 4-g-h of the silicon compound B, A-H are acid ^{_{B, R 5 g (H)}} h Si-A 4-g-h is obtained from the reaction Represents acid A. R ⁵ is independently selected from a monovalent organic group containing a hydrocarbon group having 1 to 18 carbon atoms and a monovalent organic group containing a fluoroalkyl chain having 1 to 8 carbon atoms. At least one group, and A is, independently of each other, a halogen group, —O—S (O ₂ ) —R ′, and —O—C (O) —R ′ (R ′ is partly Or at least one group selected from monovalent hydrocarbon groups having 1 to 8 carbon atoms in which all hydrogens may be replaced by fluorine. Each Z independently represents a monovalent organic group in which the element bonded to Si is nitrogen. Moreover, g is an integer of 1-3, h is an integer of 0-2, and the sum total of g and h is 1-3. In Formula [6], ZH is a by-product and may be a component that does not contribute to the formation of the protective film.

  The chemical solution for forming a protective film of the present invention may contain a mixture of the silicon compound A and the acid A as a catalyst obtained by the reaction of the formula [6]. Further, the silicon compound B is excessively added to the acid B, and the silicon compound B not consumed in the reaction of the formula [6] reacts with the acid A generated by the reaction to form the protective film. You may do. That is, the surplus of the silicon compound B that has not been consumed in the reaction of the formula [6] may contribute to the formation of the protective film as the silicon compound A. The silicon compound B is preferably 0.2 to 100000 mol times, preferably 0.5 to 50000 mol times, and more preferably 1 to 10000 mol times with respect to the acid B. .

  In addition, as long as the acid A as a catalyst is obtained like the right side of said Formula [6], you may utilize reaction other than the reaction of the said silicon compound B and the acid B. FIG.

The monovalent organic group in which the element bonded to Si as Z of the silicon compound B on the left side of the formula [6] is nitrogen is not only hydrogen, carbon, nitrogen, oxygen but also silicon, sulfur, halogen elements, etc. It may be included. Examples of the monovalent organic group in which the element bonded to Si is nitrogen include an isocyanate group, an amino group, a dialkylamino group, an isothiocyanate group, an azide group, an acetamide 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, an imidazole ring, an oxazolidinone ring, morpholine _{ring, -NH-C (O) -Si} (CH 3) 3, -N (H _2-i (Si (H) _j R ⁶ _3-j ) _i (R ⁶ is a monovalent hydrocarbon group having 1 to 18 carbon atoms in which part or all of hydrogen may be replaced by fluorine. , I is 1 or 2, j is an integer of 0-2).

Among these, Z of the silicon compound B on the left side of the formula [6] is —N (CH ₃ ) ₂ , —NH ₂ , —N (C ₂ H ₅ ) ₂ , —N (CH ₃ ) C (O). _{CH 3, -N (CH 3)} C (O) CF 3, -NHC (O) -NH-Si (CH 3) 3, an imidazole ring, -NH-C (O) -Si (CH 3) 3, - _{N (H) 2-p (} Si (H) q R 7 3-q) p (R 7 is a part or all of hydrogen carbon atoms, which may have been replaced by fluorine monovalent 1-8 A hydrocarbon group, p is 1 or 2, and q is an integer of 0 to 2.

  Examples of the acid B on the left side of the formula [6] include inorganic acids and organic acids. Examples of inorganic acids include organic acids such as hydrogen halide, sulfuric acid, perchloric acid, and phosphoric acid. As alkane sulfonic acid, carboxylic acid, benzene sulfonic acid, p-toluene sulfonic acid, etc., in which some or all of hydrogen may be substituted with fluorine atoms or the like. In particular, hydrogen chloride, trifluoromethanesulfonic acid, and trifluoroacetic acid are preferable.

  The amount of water in the chemical solution is preferably 5000 ppm by mass or less with respect to the total amount of the chemical solution. When the amount of water exceeds 5000 ppm by mass, the activity of the silicon compound A and / or the reaction promoting effect of the acid A is reduced, and it becomes difficult to form the protective film in a short time. Therefore, it is preferable that the silicon compound A and the aprotic organic solvent contained in the chemical solution do not contain much water. The water content in the chemical solution may be 10 ppm or more.

  Moreover, it is preferable that the number of particles larger than 0.5 μm in particle measurement by a light scattering type submerged particle detector in the liquid phase of the chemical solution is 100 or less per 1 mL of the chemical solution. If the number of particles larger than 0.5 μm exceeds 100 per 1 mL of the chemical solution, pattern damage due to the particles may be induced, which causes a decrease in device yield and reliability. Further, it is preferable that the number of particles larger than 0.5 μm is 100 or less per mL of the chemical solution because washing with a solvent or water after forming the protective film can be omitted or reduced. For this reason, it is preferable that the number of particles larger than 0.5 μm per 1 mL of the chemical solution in the chemical solution is smaller, but the number of particles larger than 0.5 μm may be 1 or more per 1 mL of the chemical solution. The particle measurement in the liquid phase in the chemical solution in the present invention is performed by using a commercially available measuring device in the light scattering liquid particle measurement method using a laser as a light source. , PSL (polystyrene latex) standard particle-based light scattering equivalent diameter.

  Moreover, it is preferable that the metal impurity content of each element of Na, Mg, K, Ca, Mn, Fe and Cu in the chemical solution is 100 mass ppb or less with respect to the total amount of the chemical solution. The metal impurities of each element described above are all those that exist in the chemical solution in the form of metal fine particles, ions, colloids, complexes, oxides and nitrides, whether dissolved or undissolved. If the metal impurity content is more than 100 mass ppb with respect to the total amount of the chemical solution, the junction leakage current of the device may be increased, which causes a decrease in device yield and reliability. Moreover, it is preferable that the metal impurity content is 100 mass ppb or less with respect to the total amount of the chemical solution because washing with a solvent or water after forming the protective film can be omitted or reduced. In addition, 0.01 mass ppb or more of each said metal impurity content may be sufficient with respect to this chemical | medical solution total amount.

  In the method for preparing a chemical solution for forming a protective film in which the silicon compound A represented by the general formula [1] and the acid A as a catalyst are mixed and contained, the silicon compound A before mixing, the acid A, and after mixing It is preferable to purify at least one of the mixed solutions. When the protective film-forming chemical solution contains a solvent, the silicon compound A and the acid A before mixing may be in a solution state containing a solvent. In this case, the purification is performed before the silicon before mixing. The target may be at least one of compound A or a solution thereof, acid A or a solution thereof, and a mixed solution after mixing.

  The purification includes removal of water molecules by adsorbent such as molecular sieve or distillation, removal of metal impurities of each element of Na, Mg, K, Ca, Mn, Fe and Cu by ion exchange resin or distillation, and This is performed using at least one removing means among removing contaminants such as particles by filter filtration. In consideration of the activity of the chemical solution for forming the protective film and the cleanliness of the wafer, it is preferable to remove water molecules, remove metal impurities, and remove contaminants, and the removal order is not limited.

  Moreover, the chemical | medical solution for protective film formation of this invention can be stored in the state which divided the raw material into two or more, and can also be mixed and used before use. For example, when the silicon compound A and the acid A as the catalyst are used as a part of the raw material for the protective film forming chemical, the silicon compound A and the acid A as the catalyst can be stored separately and mixed before use. . When using the silicon compound B and the acid B, the silicon compound B and the acid B can be stored separately and mixed before use. The silicon compound and the acid before mixing may be in a solution state. In addition, the above silicon compound and acid can be stored in the same solution and mixed with another raw material before use.

  Hereinafter, a method of making the wafer surface a surface having a fine uneven pattern will be described. First, after applying a resist to the 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. . 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 concave portion of the resist pattern is selectively etched. Finally, when the resist is removed, a wafer having a fine uneven pattern is obtained.

  As a wafer having a fine concavo-convex pattern on the surface and at least a part of the concavo-convex pattern containing silicon, the wafer surface is formed with a silicon-containing film such as silicon, silicon oxide, silicon nitride, or the concavo-convex pattern. When the pattern is formed, those in which at least a part of the surface of the concavo-convex pattern contains silicon or silicon such as silicon oxide and silicon nitride are included.

  In addition, a wafer composed of a plurality of components including at least one selected from silicon, silicon oxide, and silicon nitride also repels at least one surface selected from silicon, silicon oxide, and silicon nitride. An aqueous protective film can be formed. As the wafer composed of the plurality of components, at least one selected from silicon, silicon oxide, and silicon nitride is formed on the wafer surface, or when a concavo-convex pattern is formed, at least one of the concavo-convex pattern is formed. A part whose part is at least one selected from silicon, silicon oxide, and silicon nitride is also included.

  After making the wafer surface a surface having a fine uneven pattern, cleaning the surface with an aqueous cleaning liquid and removing the aqueous cleaning liquid by drying or the like, the pattern collapses when the width of the concave portion is small and the aspect ratio of the convex portion is large. Is likely to occur. The concavo-convex pattern is defined as shown in FIGS. FIG. 1 is a schematic view when a wafer 1 whose surface is a surface having a fine concavo-convex pattern 2 is viewed in perspective, and FIG. 2 shows a part of a cross section aa ′ in FIG. . 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 in the cleaning process 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.

  In a preferred embodiment of the present invention, as described in the above (Step 1), after making the wafer surface a surface having a fine concavo-convex pattern, an aqueous cleaning solution is applied to the surface, and the aqueous cleaning solution is applied to at least the concave surface of the concavo-convex pattern. Hold. Then, as described in the above (Step 2), the aqueous cleaning liquid held on at least the concave surface of the concavo-convex pattern is replaced with a cleaning liquid A different from the aqueous cleaning liquid. Preferred examples of the cleaning liquid A include at least one of a chemical solution for forming a protective film specified in the present invention, water, an organic solvent, or a mixture thereof, or an acid, an alkali, a surfactant, and an oxidizing agent. Are mixed. Further, when a liquid other than the chemical liquid is used as the cleaning liquid A, it is preferable to replace the cleaning liquid A with the protective film-forming chemical liquid in a state where the cleaning liquid A is held on at least the concave surface of the concavo-convex pattern.

  Examples of the organic solvent which is one of the preferred examples of the cleaning liquid A include hydrocarbons, esters, ethers, ketones, halogen-containing solvents, sulfoxide solvents, alcohols, polyhydric alcohol derivatives, And nitrogen-containing compound solvents.

  Examples of the hydrocarbons include toluene, benzene, xylene, hexane, heptane, and octane. Examples of the esters include ethyl acetate, propyl acetate, butyl acetate, and ethyl acetoacetate, and the ether. Examples of such classes include diethyl ether, dipropyl ether, dibutyl ether, tetrahydrofuran, dioxane and the like, and examples of the ketones include acetone, acetylacetone, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, cyclohexanone, isophorone, and the like. Examples of the halogen-containing solvent include perfluorocarbons such as perfluorooctane, perfluorononane, perfluorocyclopentane, perfluorocyclohexane, hexafluorobenzene, 1,1,1, , 3-pentafluorobutane, octafluorocyclopentane, 2,3-dihydrodecafluoropentane, hydrofluorocarbons such as Zeolora H (manufactured by Nippon Zeon), methyl perfluoroisobutyl ether, methyl perfluorobutyl ether, ethyl perfluorobutyl ether, Hydrofluoroethers such as ethyl perfluoroisobutyl ether, Asahiklin AE-3000 (manufactured by Asahi Glass), Novec HFE-7100, Novec HFE-7200, Novec 7300, and Novec 7600 (all from 3M), chlorocarbons such as tetrachloromethane, chloroform Hydrochlorocarbons such as chlorofluorocarbons such as dichlorodifluoromethane, 1,1-dichloro-2,2,3,3,3-pe Tafluoropropane, 1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1-chloro-3,3,3-trifluoropropene, 1,2-dichloro-3,3,3- There are hydrochlorofluorocarbons such as trifluoropropene, perfluoroethers, perfluoropolyethers, etc. Examples of the sulfoxide solvents include dimethyl sulfoxide, and examples of alcohols include methanol, ethanol, propanol, butanol. Ethylene glycol, 1,3-propanediol, etc. Examples of the derivative of the polyhydric alcohol include diethylene glycol monoethyl ether, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether. , Propylene glycol monoethyl ether, 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 glycol dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol diacetate , Ethylene glycol diacetate, ethylene glycol diethyl ether, ethylene glycol dimethyl ether, etc. Examples of nitrogen-containing compound solvents include formamide, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone , Diethylamine, Examples include triethylamine and pyridine.

  Examples of acids that can be mixed with the cleaning liquid A 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 cleaning liquid A include ammonia and choline. Examples of the oxidizing agent that may be mixed with the cleaning liquid A include ozone and hydrogen peroxide.

  In addition, it is preferable that the cleaning liquid A is an organic solvent because the chemical liquid for forming a protective film can be provided to the recess without being brought into contact with water. Further, it is preferable that the cleaning liquid A contains an acid aqueous solution because the protective film can be formed in a short time.

  A plurality of cleaning liquids may be used as the cleaning liquid A. For example, two types of cleaning liquid containing the acid aqueous solution and the organic solvent cleaning liquid can be used.

  FIG. 3 is a schematic view showing a state in which the recess 4 holds the protective film forming chemical 8 in the cleaning process. The wafer in the schematic diagram of FIG. 3 shows a part of the a-a ′ cross section of FIG. 1. In the cleaning process, the protective film forming chemical is supplied to the wafer 1 on which the concave / convex pattern 2 is formed. At this time, the chemical solution is held in the recess 4 as shown in FIG. 3, and a protective film is formed on the surface of the recess 4 to make the surface water repellent.

  When the temperature of the protective film-forming chemical is increased, the protective film can be easily formed in a shorter time. The temperature at which a homogeneous protective film is easily formed is preferably 10 ° C. or higher and lower than the boiling point of the chemical solution, and more preferably 15 ° C. or higher and lower than 10 ° C. lower than the boiling point of the chemical solution. The temperature of the chemical solution is preferably maintained at the temperature even when held on at least the concave surface of the concave / convex pattern.

  Other cleaning liquids may also 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 A contains an acid aqueous solution, particularly preferably a solution containing an acid aqueous solution and an organic solvent having a boiling point of 100 ° C. or higher, the protective film can be shortened for a short time if the temperature of the cleaning liquid is raised near the boiling point of the cleaning liquid. It is preferable because it is easy to form.

  After the step (Step 3) of holding the protective film-forming chemical solution on at least the concave surface of the concave / convex pattern, after replacing the chemical solution held on at least the concave surface of the concave / convex pattern with a cleaning liquid B different from the chemical solution The step of removing the liquid from the surface of the concavo-convex pattern by drying (step 4) may be performed. Examples of the cleaning liquid B include an aqueous cleaning liquid composed of an aqueous solution, an organic solvent, or the aqueous cleaning liquid and the organic solvent. A mixture of at least one of an acid, an alkali and a surfactant, or a silicon compound A contained in a chemical solution for forming a protective film, and an acid A as a catalyst is lower than the chemical solution. The thing added so that it might become a density | concentration etc. are mentioned.

  Examples of the organic solvent which is one of the preferable examples of the cleaning liquid B include hydrocarbons, esters, ethers, ketones, halogen-containing solvents, sulfoxide solvents, alcohols, polyhydric alcohol derivatives, And nitrogen-containing compound solvents.

  Examples of the hydrocarbons include toluene, benzene, xylene, hexane, heptane, and octane. Examples of the esters include ethyl acetate, propyl acetate, butyl acetate, and ethyl acetoacetate, and the ether. Examples of such classes include diethyl ether, dipropyl ether, dibutyl ether, tetrahydrofuran, dioxane and the like, and examples of the ketones include acetone, acetylacetone, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, cyclohexanone, and isophorone. Examples of the halogen-containing solvent include perfluorocarbons such as perfluorooctane, perfluorononane, perfluorocyclopentane, perfluorocyclohexane, hexafluorobenzene, 1,1,1, , 3-pentafluorobutane, octafluorocyclopentane, 2,3-dihydrodecafluoropentane, hydrofluorocarbons such as Zeolora H (manufactured by Nippon Zeon), methyl perfluoroisobutyl ether, methyl perfluorobutyl ether, ethyl perfluorobutyl ether, Hydrofluoroethers such as ethyl perfluoroisobutyl ether, Asahiklin AE-3000 (manufactured by Asahi Glass), Novec HFE-7100, Novec HFE-7200, Novec 7300, and Novec 7600 (all from 3M), chlorocarbons such as tetrachloromethane, chloroform Hydrochlorocarbons such as chlorofluorocarbons such as dichlorodifluoromethane, 1,1-dichloro-2,2,3,3,3-pe Tafluoropropane, 1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1-chloro-3,3,3-trifluoropropene, 1,2-dichloro-3,3,3- There are hydrochlorofluorocarbons such as trifluoropropene, perfluoroethers, perfluoropolyethers, etc. Examples of the sulfoxide solvents include dimethyl sulfoxide, and examples of alcohols include methanol, ethanol, propanol, butanol. Ethylene glycol, 1,3-propanediol, etc. Examples of the derivative of the polyhydric alcohol include diethylene glycol monoethyl ether, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether. , Propylene glycol monoethyl ether, 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 glycol dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol diacetate , Ethylene glycol diacetate, ethylene glycol diethyl ether, ethylene glycol dimethyl ether, etc. Examples of nitrogen-containing compound solvents include formamide, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone , Diethylamine, Examples include triethylamine and pyridine.

  In addition, after the replacement with the cleaning liquid B, an aqueous cleaning liquid composed of an aqueous solution is held on at least the concave surface of the concave / convex pattern, and then the process may be shifted to a step of removing the liquid from the concave / convex pattern surface by drying (step 4). .

  A plurality of cleaning liquids may be used as the cleaning liquid B. For example, an organic solvent (preferably containing a water-soluble organic solvent) and an aqueous cleaning solution can be used.

  Examples of the aqueous cleaning liquid include water or water mainly containing water mixed with at least one organic solvent, acid or alkali in water (for example, the water content is 50% by mass or more). It is done. In particular, when water is used as the aqueous cleaning liquid, the contact angle θ with the liquid on at least the concave surface of the concave / convex pattern made water repellent by the chemical solution increases, and the capillary force P on the concave surface decreases, and further after drying. This is preferable because dirt on the wafer surface is less likely to remain.

  FIG. 4 shows a schematic diagram when the aqueous cleaning liquid is held in the recess 4 made water repellent by the protective film forming chemical. The wafer in the schematic diagram of FIG. 4 shows a part of the a-a ′ cross section of FIG. 1. The surface of the concavo-convex pattern is made water-repellent by forming the water-repellent protective film 10 with the chemical. The protective film 10 is held on the wafer surface even when the aqueous cleaning liquid 9 is removed from the uneven pattern surface.

When the protective film 10 is formed on at least the concave surface of the concave / convex pattern of the wafer with the chemical solution for forming the protective film, the contact angle is 50 to 130 ° when it is assumed that water is retained on the surface. It is preferable because it does not easily fall over. Further, the closer the contact angle is to 90 °, the smaller the capillary force on the surface of the recess and the more difficult the pattern collapse occurs. The capillary force is preferably 2.1 MN / m ² or less. It is preferable that the capillary force is 2.1 MN / m ² or less because pattern collapse hardly occurs. Also, when the capillary force is small, the collapse is further difficult to occur pattern, capillary force is particularly preferably 1.5Mn / ^{m 2} or less, more preferably 1.0 MN / ^{m 2} or less. Furthermore, it is ideal to adjust the contact angle with the cleaning liquid to around 90 ° so that the capillary force is as close to 0.0 MN / m ² as possible.

  Next, as described in the above (Step 4), a step of removing the liquid from the surface of the concavo-convex pattern by drying is performed. In this step, the liquid held on the uneven pattern surface is removed by drying. The drying is preferably performed by a known drying method such as spin drying, IPA (2-propanol) vapor drying, Marangoni drying, heat drying, hot air drying, or vacuum drying.

  When the liquid is removed from the surface of the concavo-convex pattern, the liquid held on the surface may be the chemical liquid, the cleaning liquid B, the aqueous cleaning liquid, and a mixture thereof. The liquid mixture containing the chemical liquid may be a liquid in the middle of replacing the chemical liquid with the cleaning liquid B, or may be a liquid mixture obtained by previously mixing the chemical liquid with a cleaning liquid different from the chemical liquid. Further, after the liquid is once removed from the uneven pattern surface, the uneven pattern surface is held with at least one selected from the cleaning liquid B, the aqueous cleaning liquid, and a mixture thereof, and then dried. Also good.

  Next, as described in the above (Step 5), by performing at least one treatment selected from light irradiation of the wafer surface, heating of the wafer, and exposure of the wafer to ozone, water repellency is achieved. A step of removing the protective film 10 is performed.

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, the wafer is heated at 400 to 700 ° C, preferably 500 to 700 ° C. This heating time is preferably 0.5 to 60 min, preferably 1 to 30 min. 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.

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

  In the step of removing the protective film on the wafer surface, the protective film on the wafer surface can be efficiently removed by combining the light irradiation treatment, the heat treatment, and the ozone exposure treatment. In this step, plasma irradiation, corona discharge, or the like may be used in combination.

Making the surface of the wafer a surface having a fine concavo-convex pattern and replacing the cleaning liquid held on at least the concave surface of the concavo-convex pattern with other cleaning liquids have already been established through various studies in other literature. Therefore, in the present invention, the evaluation of the chemical solution for forming a protective film was mainly performed. In addition, the formula P = 2 × γ × cos θ / S (γ: surface tension, θ: contact angle, S: pattern dimension) described in the background art, etc.
As can be seen from the above, the pattern collapse greatly depends on the contact angle of the cleaning liquid to the wafer surface, that is, the contact angle of the droplets and the surface tension of the cleaning liquid. In the case of the cleaning liquid held in the recess 4 of the concavo-convex pattern 2, the contact angle of the droplet and the capillary force on the surface of the recess, which can be considered as equivalent to the pattern collapse, are correlated. The capillary force may be derived from the evaluation of the contact angle of the droplet of the protective film 10. In the examples, water, which is a typical aqueous cleaning solution, was used as the cleaning solution.

  However, in the case of a wafer having a fine concavo-convex pattern on the surface, since the pattern is very fine, the contact angle of the protective film 10 formed on the concavo-convex pattern surface cannot be accurately evaluated.

  The contact angle of water droplets is evaluated by dropping several μl of water droplets on the sample (base material) surface as in JIS R 3257 “Test method for wettability of substrate glass surface”, and the angle between the water droplet and the substrate surface. It is made by measuring. 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 present invention, 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 fine uneven pattern 2 is formed. Various evaluations were made considering the protective film 10. In the present invention, as a wafer having a smooth surface, a silicon wafer having a surface having a thermal oxide film layer, a silicon nitride layer or a silicon layer and having a smooth surface is used.

  Details are described below. In the following, the evaluation method of the protective film forming chemical solution, the evaluation method of the wafer provided with the protective film forming chemical solution, the preparation of the protective film forming chemical solution, and after providing the protective film forming chemical solution to the wafer The evaluation results are stated.

[Method for evaluating protective film-forming chemical]
The following evaluations (1) to (2) were performed as evaluation methods for the chemical solution for forming a protective film.

(1) Water displacement of chemical solution for forming a protective film A silicon wafer with a smooth thermal oxide film (Si wafer having a 1 μm thick thermal oxide film layer on the surface) is immersed in a 1% by mass hydrofluoric acid aqueous solution at room temperature for 2 minutes. Then, it was immersed in pure water for 1 min. Next, the wafer was immersed in a protective film forming chemical solution for 5 minutes while the wafer was wet with pure water. After immersion, a product in which water did not remain on the wafer surface by visual observation was regarded as acceptable (denoted as “◯” in the table).

(2) pH measurement of chemical solution for forming protective film A 25 ° C chemical solution was attached to pH test paper (WR manufactured by ADVANTEC), and the pH was measured.

[Evaluation method of wafer provided with chemical solution for forming protective film]
The following evaluations (1) to (4) 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). It was measured by Interface Science: CA-X type). Here, the contact angle of the protective film in the range of 50 to 130 ° was determined to be acceptable (denoted as “◯” in the table).

(2) Evaluation of capillary force P was calculated using the following equation, and the capillary force (absolute value of P) was determined.
P = 2 × γ × cos θ / S
Here, γ is the surface tension, θ is the contact angle, and S is the pattern dimension. In the pattern with a line width of 45 nm, the pattern tends to collapse when the cleaning liquid is water when the wafer passes through the gas-liquid interface, and the pattern does not easily collapse when the wafer is 2-propanol. When the pattern size is 45 nm and the wafer surface is silicon oxide, the capillary force is 0.98 MN / m ² when the cleaning liquid is 2-propanol (surface tension: 22 mN / m, contact angle with silicon oxide: 1 °). On the other hand, the capillary force is 3.2 MN / m ^{2 in} water (surface tension: 72 mN / m, contact angle with silicon oxide: 2.5 °) having the largest surface tension among liquids excluding mercury. Therefore, the target is 2.1 MN / m ^{2 in the} middle, and if the capillary force when water is retained is 2.1 MN / m ² or less, it is accepted (indicated by ○ in the table), and 2.1 MN / m ² Those exceeding the mark were regarded as unacceptable (denoted as x in the table).

(3) Removability of protective film The sample was irradiated with UV light from a metal halide lamp for 2 hours under the following conditions. A sample having a water droplet contact angle of 30 ° or less after irradiation was regarded as acceptable (denoted as “◯” in the table).
-Lamp: M0155-L312 (strength: 1.5 kW) manufactured by Eye Graphics
Illuminance: The measured value under the following conditions is 128 mW / cm ²
Measuring device: UV intensity meter (Konica Minolta Sensing, UM-10)
-Light receiving part: UM-360
(Receiving wavelength: 310 to 400 nm, peak wavelength: 365 nm)
・ Measurement mode: Irradiance measurement

(4) 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) 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 of the wafer after removing the protective film is 1 nm or less, the wafer surface is not eroded by cleaning, and there is no residue of the chemical on the wafer surface. It was.

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 Trimethylchlorosilane [(CH ₃ ) ₃ SiCl] as silicon compound A; 5 g, solubility of propylene glycol monomethyl ether acetate (PGMEA, 100 parts by weight of water as water-soluble aprotic organic solvent) : 22 parts by weight); 95 g was mixed and stirred for about 5 minutes. The concentration of silicon compound A relative to the total amount of the water-repellent cleaning solution (hereinafter referred to as “silicon compound concentration”) was 5% by mass, based on the total amount of the water-repellent cleaning solution. A chemical solution for forming a protective film having a water-soluble aprotic organic solvent concentration (hereinafter referred to as “water-soluble organic solvent concentration”) of 95% by mass was obtained. Furthermore, water is removed from the chemical solution with molecular sieve 4A (made by Union Showa), then metal impurities are removed from the chemical solution with ion exchange resin (Nippon Pole's Ion Clean SL), and then filtered (Nippon Entegris). Particles were removed from the chemical solution using an optimizer) for purification. When the water content in the chemical solution after purification was measured with a Karl Fischer moisture meter (ADP-511, manufactured by Kyoto Electronics Co., Ltd.), the water content in the chemical solution after purification was 6 mass relative to the total amount of the chemical solution. ppm. Further, when the metal impurity content in the chemical solution after purification was measured by an inductively coupled plasma mass spectrometer (Yokogawa Analytical Systems, Agilent 7500cs type), Na, Mg, K, The metal impurity content of each element of Ca, Mn, Fe, and Cu is Na = 2 mass ppb, Mg = 0.04 mass ppb, K = 0.2 mass ppb, Ca = 1 mass with respect to the total amount of the chemical solution, respectively. It was ppb, Mn = 0.005 mass ppb, Fe = 0.08 mass ppb, Cu = 0.06 mass ppb. Further, when the number of particles larger than 0.5 μm in the particle measurement by the light scattering liquid particle detector in the liquid phase was measured with a light scattering liquid particle measuring device (Lion Co., Ltd., KS-42AF type), The number of particles larger than 0.5 μm was 2 per 1 mL of the drug solution. In addition, also in the examples after this example, the same purification was performed, the water content was 5000 ppm by mass or less with respect to the total amount of the chemical solution, and the metal of each element of Na, Mg, K, Ca, Mn, Fe and Cu Impurity content was 100 mass ppb or less with respect to the total amount of the chemical solution, and a chemical solution was confirmed that the number of particles larger than 0.5 μm was 100 or less per mL of the chemical solution.

(2) Cleaning of silicon wafer A silicon wafer with a smooth SiO ₂ film (Si wafer having a 1 μm thick thermal oxide film layer on the surface) is immersed in a 1% by mass hydrofluoric acid aqueous solution at room temperature for 2 minutes, and then purified water It was immersed for 1 min in 2-propanol (iPA) for 1 min. Further, a silicon wafer with a SiN film (a silicon wafer having a silicon nitride film with a thickness of 50 nm on the surface) produced by LP-CVD and a silicon wafer with a polysilicon film were immersed in a 1% by mass hydrofluoric acid aqueous solution for 2 min. Subsequently, it was immersed in pure water for 1 min, 28% by mass ammonia water: 30% by mass hydrogen peroxide water: water in a mixing solution of 1: 1: 5 for 1 min and in pure water for 1 min.

(3) Surface treatment with a protective film forming chemical on the silicon wafer surface The silicon wafer was immersed for 10 minutes at 20 ° C. in the protective film forming chemical prepared in “(1) Preparation of protective film forming chemical”. Thereafter, the silicon wafer was immersed in iPA for 1 min, and then immersed in pure water as an aqueous cleaning solution for 1 min. Finally, the silicon 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 60 °, which showed the effect of imparting water repellency. Moreover, when the capillary force when water was held was calculated using the formula described in the above “Evaluation of Capillary Force”, the capillary force was 1.6 MN / m ² and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 2
All were the same as Example 1 except that the concentration of silicon compound A in the chemical solution for forming the protective film was 10% by mass. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 68 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 1.2 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 3
All were the same as Example 2 except that dimethylchlorosilane [(CH ₃ ) ₂ Si (H) Cl] was used as the silicon compound A in the protective film forming chemical. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 78 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.7 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 4
All were the same as Example 2 except that (trifluoropropyl) trichlorosilane [CF ₃ CH ₂ CH ₂ SiCl ₃ ] was used as the silicon compound A in the chemical solution for forming the protective film. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 74 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.9 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 5
All were the same as Example 2 except that (trifluoropropyl) dimethylchlorosilane [CF ₃ CH ₂ CH ₂ Si (CH ₃ ) ₂ Cl] was used as the silicon compound A in the protective film-forming chemical solution. As shown in Table 1, the evaluation results showed that the contact angle after the surface treatment was 70 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 1.1 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 6
All were the same as in Example 2 except that (octyl) dimethylchlorosilane [C ₈ H ₁₇ Si (CH ₃ ) ₂ Cl] was used as the silicon compound A in the protective film-forming chemical solution. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 80 °, which showed the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.6 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 7
All were the same as Example 1 except that trimethylsilyl trifluoromethanesulfonate [(CH ₃ ) ₃ Si—OS (O ₂ ) CF ₃ ] was used as the silicon compound A in the protective film forming chemical. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 86 °, indicating water repellency imparting effect. Further, the capillary force when water was held was 0.2 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 8
3 g of trimethylmethoxysilane [(CH ₃ ) ₃ Si—OCH ₃ ] as the silicon compound A in the chemical solution for forming the protective film; trimethylsilyl trifluoromethanesulfonate [(CH ₃ ) ₃ Si—OS (O ₂ ) as an acid as a catalyst CF ₃ ]; 1 g and PGMEA; 96 g as a water-soluble aprotic organic solvent were mixed to obtain a protective film-forming chemical solution, and all the procedures were the same as in Example 1. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 9
All were the same as Example 8 except that the acid as a catalyst was trifluoromethanesulfonic anhydride [(CF ₃ SO ₂ ) ₂ O]. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 10
All were the same as Example 8 except that the acid as the catalyst was trifluoromethanesulfonic acid [CH ₃ S (O ₂ ) OH]. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 11
All were the same as Example 10 except that the concentration of silicon compound A in the chemical solution for forming the protective film was 10% by mass. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 88 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.1 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 12
All were the same as Example 8 except that the acid as the catalyst was 98% sulfuric acid [H ₂ SO ₄ ]. As shown in Table 1, the evaluation results showed that the contact angle after the surface treatment was 70 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 1.1 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 13
Hexamethyldisilazane [(H ₃ C) ₃ Si—NH—Si (CH ₃ ) ₃ ] as the silicon compound A in the protective film forming chemical solution; 1 g, PGMEA as the water-soluble aprotic organic solvent; 98.9 g Were mixed. Furthermore, all except that trimethylsilyl trifluoroacetate [(CH ₃ ) ₃ Si—OC (O) CF ₃ ]; 0.1 g was mixed as an acid as a catalyst to obtain a chemical solution for forming a protective film. Same as above. The pH values of the mixed solution of hexamethyldisilazane and PGMEA and the chemical solution for forming a protective film were 8 and 7, respectively. Moreover, as shown in Table 1, the evaluation results of the protective film showed a contact angle after the surface treatment of 84 °, indicating a water repellency imparting effect. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 14
All were the same as Example 13 except that the concentration of silicon compound A in the chemical solution for forming the protective film was 5 mass%. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 86 °, indicating water repellency imparting effect. Further, the capillary force when water was held was 0.2 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 15
All were the same as Example 13 except that the concentration of silicon compound A in the chemical solution for forming the protective film was 10% by mass. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 88 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.1 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 16
All were the same as Example 13 except that ethylene glycol monomethyl ether acetate (EGMEA, solubility in water: arbitrarily dissolved) was used as the water-soluble aprotic organic solvent in the chemical solution for forming the protective film. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 17
All were the same as Example 13 except that ethylene glycol dimethyl ether (monoglyme, solubility in water: arbitrarily dissolved) was used as the water-soluble aprotic organic solvent in the chemical solution for forming the protective film. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 82 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.4 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 18
All were the same as Example 13 except that diethylene glycol dimethyl ether (diglyme, solubility of water: arbitrarily dissolved) was used as the water-soluble aprotic organic solvent in the chemical solution for forming the protective film. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 82 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.4 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 19
Hexamethyldisilazane [(H ₃ C) ₃ Si—NH—Si (CH ₃ ) ₃ ] as the silicon compound A in the protective film forming chemical solution; 1 g, trimethylsilyl trifluoroacetate [(CH ₃ ) as the acid as the catalyst ₃ Si—OC (O) CF ₃ ]; 0.1 g, PGMEA as a water-soluble aprotic organic solvent; 88.9 g, fluorine-based solvent as other organic solvent (Novec HFE-7100 manufactured by Sumitomo 3M: Hydrofluoroether ); All were the same as Example 13 except that 10.0 g was mixed to obtain a chemical solution for forming a protective film. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 20
All were the same as Example 19 except that 1-chloro-3,3,3-trifluoropropene (CTFP) was used as the other solvent in the chemical solution for forming the protective film. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 21
All were the same as Example 19 except that 1,2 dichloro-3,3,3-trifluoropropene (DCTFP) was used as the other solvent in the protective film forming chemical. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 22
All were the same as Example 13 except that trimethylsilyl trifluoromethanesulfonate [(CH ₃ ) ₃ SiOS (O ₂ ) CF ₃ ] was used as the acid in the chemical solution for forming the protective film. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 80 °, which showed the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.6 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 23
All were the same as Example 13 except that trifluoroacetic anhydride [{CF ₃ C (O)} ₂ O] was used as the acid in the chemical solution for forming the protective film. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 82 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.4 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 24
All were the same as Example 13 except that trifluoromethanesulfonic anhydride [{CF ₃ S (O ₂ )} ₂ O] was used as the acid in the protective film forming chemical. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 80 °, which showed the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.6 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 25
All were the same as Example 13 except that trimethylsilylchlorosilane [(CH ₃ ) ₃ SiCl] was used as the acid in the chemical solution for forming the protective film. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 78 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.7 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 26
All were the same as Example 13 except that trifluoroacetic acid [CF ₃ C (O) OH] was used as the acid in the protective film forming chemical. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 27
All were the same as Example 13 except that trifluoromethanesulfonic acid [CF ₃ S (O ₂ ) OH] was used as the acid in the protective film forming chemical. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 80 °, which showed the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.6 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 28
Example 13 is the same as Example 13 except that tetramethyldisilazane [(H ₃ C) ₂ Si (H) —NH—Si (H) (CH ₃ ) ₂ ] is used as the silicon compound A in the protective film forming chemical solution. Same as above. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 86 °, indicating water repellency imparting effect. Further, the capillary force when water was held was 0.2 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 29
Examples All except that diphenyltetramethyldisilazane [C ₆ H ₅ Si (CH ₃ ) ₂ —NH—Si (CH ₃ ) ₂ C ₆ H ₅ ] was used as the silicon compound A in the chemical solution for forming the protective film Same as 28. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 86 °, indicating water repellency imparting effect. Further, the capillary force when water was held was 0.2 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 30
As silicon compound A in the chemical solution for forming a protective film, 1,3-bis (trifluoropropyl) tetramethyldisilazane [CF ₃ CH ₂ CH ₂ Si (CH ₃ ) ₂ —NH—Si (CH ₃ ) ₂ CH ₂ All were the same as Example 28 except that CH ₂ CF ₃ ] was used. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 31
All were the same as in Example 28 except that trimethylsilyldimethylamine [(CH ₃ ) ₃ Si—N (CH ₃ ) ₂ ] was used as the silicon compound A in the protective film forming chemical. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 82 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.4 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 32
All were the same as Example 28 except that trimethylsilyldiethylamine [(CH ₃ ) ₃ Si—N (C ₂ H ₅ ) ₂ ] was used as the silicon compound A in the protective film forming chemical. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 33
All were the same as in Example 28 except that trimethylsilyl isocyanate [(CH ₃ ) ₃ Si—NCO] was used as the silicon compound A in the protective film forming chemical. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 80 °, which showed the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.6 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 34
All were the same as Example 28 except that trimethylsilylimidazole represented by the following formula was used as the silicon compound A in the protective film forming chemical. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 82 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.4 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 35
The same as Example 28, except that butyldimethyl (dimethylamino) silane [C ₄ H ₉ Si (CH ₃ ) ₂ —N (CH ₃ ) ₂ ] was used as the silicon compound A in the protective film forming chemical. did. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 92 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.1 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 36
The same as Example 28, except that octyldimethyl (dimethylamino) silane [C ₈ H ₁₇ Si (CH ₃ ) ₂ —N (CH ₃ ) ₂ ] was used as the silicon compound A in the protective film forming chemical. did. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 104 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.8 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 37
Example 19 is the same as Example 19 except that tetramethyldisilazane [(H ₃ C) ₂ Si (H) —NH—Si (H) (CH ₃ ) ₂ ] is used as the silicon compound A in the protective film forming chemical. Same as above. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 38
All were the same as Example 28, except that trifluoroacetic anhydride [{CF ₃ C (O)} ₂ O] was used as the acid in the chemical solution for forming the protective film. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 86 °, indicating water repellency imparting effect. Further, the capillary force when water was held was 0.2 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 39
All were the same as in Example 28 except that trifluoromethanesulfonic anhydride [{CF ₃ S (O ₂ )} ₂ O] was used as the acid in the chemical solution for forming the protective film. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 82 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.4 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 40
All were the same as Example 28, except that trimethylsilylchlorosilane [(CH ₃ ) ₃ SiCl] was used as the acid in the protective film forming chemical. As shown in Table 1, the evaluation result showed that the contact angle after the surface treatment was 80 °, which showed the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.6 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 41
All were the same as in Example 28 except that trifluoroacetic acid [CF ₃ C (O) OH] was used as the acid in the protective film forming chemical. As shown in Table 2, the evaluation result showed that the contact angle after the surface treatment was 86 °, indicating the effect of imparting water repellency. Further, the capillary force when water was held was 0.2 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 42
All were the same as Example 28, except that trifluoromethanesulfonic acid [CF ₃ S (O ₂ ) OH] was used as the acid in the protective film forming chemical. As shown in Table 2, the evaluation result showed that the contact angle after the surface treatment was 82 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.4 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 43
All were the same as in Example 41 except that trimethylsilyldimethylamine [(CH ₃ ) ₃ Si—N (CH ₃ ) ₂ ] was used as the silicon compound A in the protective film forming chemical. As shown in Table 2, the evaluation result showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 44
All were the same as Example 41, except that trimethylsilyldiethylamine [(CH ₃ ) ₃ Si—N (C ₂ H ₅ ) ₂ ] was used as the silicon compound A in the protective film forming chemical. As shown in Table 2, the evaluation result showed that the contact angle after the surface treatment was 80 °, which showed the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.6 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 45
The same as Example 41, except that butyldimethyl (dimethylamino) silane [C ₄ H ₉ Si (CH ₃ ) ₂ —N (CH ₃ ) ₂ ] was used as the silicon compound A in the protective film forming chemical. did. As shown in Table 2, the evaluation result showed that the contact angle after the surface treatment was 92 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.1 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 46
The same as Example 41, except that octyldimethyl (dimethylamino) silane [C ₈ H ₁₇ Si (CH ₃ ) ₂ —N (CH ₃ ) ₂ ] was used as the silicon compound A in the protective film forming chemical. did. As shown in Table 2, the evaluation result showed that the contact angle after the surface treatment was 104 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.8 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 47
All were the same as Example 42, except that trimethylsilyldimethylamine [(CH ₃ ) ₃ Si—N (CH ₃ ) ₂ ] was used as the silicon compound A in the protective film forming chemical. As shown in Table 2, the evaluation result showed that the contact angle after the surface treatment was 86 °, indicating the effect of imparting water repellency. Further, the capillary force when water was held was 0.2 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 48
The same as Example 42, except that butyldimethyl (dimethylamino) silane [C ₄ H ₉ Si (CH ₃ ) ₂ —N (CH ₃ ) ₂ ] was used as the silicon compound A in the protective film forming chemical. did. As shown in Table 2, the evaluation result showed that the contact angle after the surface treatment was 94 °, indicating the effect of imparting water repellency. Further, the capillary force when water was held was 0.2 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 49
The same as Example 42, except that octyldimethyl (dimethylamino) silane [C ₈ H ₁₇ Si (CH ₃ ) ₂ —N (CH ₃ ) ₂ ] was used as the silicon compound A in the protective film forming chemical. did. As shown in Table 2, the evaluation result showed that the contact angle after the surface treatment was 104 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.8 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 50
In the above “(2) Cleaning of silicon wafer”, a silicon wafer with a smooth thermal oxide film (Si wafer having a thermal oxide film layer with a thickness of 1 μm on the surface) is immersed in a 1 mass% hydrofluoric acid aqueous solution at room temperature for 2 minutes. Then, it was immersed in pure water for 1 min. Further, it was the same as Example 13 except that it was immersed in a 0.3% by mass hydrochloric acid solution at 98 ° C. for 1 min, then immersed in pure water at room temperature for 1 min, and then immersed in 2-propanol (iPA) for 1 min. As shown in Table 2, the evaluation result showed that the contact angle after the surface treatment was 86 °, indicating the effect of imparting water repellency. Further, the capillary force when water was held was 0.2 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 51
Example 50 was the same as Example 50 except that a silicon wafer with a smooth silicon nitride film (Si wafer having a silicon nitride layer with a thickness of 0.3 μm on the surface) was used. As shown in Table 2, the evaluation result showed that the contact angle after the surface treatment was 78 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.7 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 52
In the above “(2) Cleaning of silicon wafer”, a silicon wafer with a smooth silicon nitride film (Si wafer having a silicon nitride layer having a thickness of 0.3 μm on the surface) is immersed in a 1% by mass hydrofluoric acid aqueous solution at room temperature for 2 min. And immersed in pure water for 1 min. Furthermore, after dipping for 1 min at 98 ° C. in a mixed solution of 0.6 mass% hydrochloric acid aqueous solution and ethylene glycol at a mass ratio of 50:50, and then dipping in pure water for 1 min at room temperature, 1 min in 2-propanol (iPA). The procedure was the same as Example 51 except for immersion. As shown in Table 2, the evaluation result showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 53
The procedure was the same as in Example 51 except that trifluoroacetic acid [CF ₃ C (O) OH] was used as the acid in the protective film forming chemical. As shown in Table 2, the evaluation result showed that the contact angle after the surface treatment was 78 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.7 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 54
The same procedure as in Example 51 was performed except that a smooth silicon wafer with a polysilicon film (Si wafer having a polysilicon layer with a thickness of 0.3 μm on the surface) was used. As shown in Table 2, the evaluation result showed that the contact angle after the surface treatment was 78 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.7 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 55
Example 52 was the same as Example 52 except that a smooth silicon wafer with a polysilicon film (Si wafer having a polysilicon layer with a thickness of 0.3 μm on the surface) was used. As shown in Table 2, the evaluation result showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Example 56
Example 53 was the same as Example 53 except that a smooth silicon wafer with a polysilicon film (Si wafer having a polysilicon layer with a thickness of 0.3 μm on the surface) was used. As shown in Table 2, the evaluation result showed that the contact angle after the surface treatment was 80 °, which showed the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.6 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation. Moreover, the water substitution property of the chemical solution for forming a protective film was good.

Comparative Example 1
The same procedure as in Example 1 was performed except that the silicon wafer was not supplied with the chemical solution for forming the protective film. That is, in this comparative example, a wafer having a surface state that is not water-repellent was evaluated. As shown in Table 2, the contact angle of the wafer was as low as 3 °, and the capillary force when water was retained was as large as 3.2 MN / m ² .

Comparative Example 2
All were the same as Example 13 except that only the fluorine-based solvent (Novec HFE-7100 manufactured by Sumitomo 3M) was used as the solvent in the chemical solution for forming the protective film. As shown in Table 2, the evaluation results showed that the water replacement property of the protective film forming chemical was poor.

Example 57
As silicon compound B, hexamethyldisilazane [(H ₃ C) ₃ Si—NH—Si (CH ₃ ) ₃ ]; 1 g, as acid B trifluoroacetic acid [CF ₃ C (O) OH]; 0.1 g 98.9 g of PGMEA as an organic solvent is mixed and reacted as shown in the following formula to protect trimethylsilyl trifluoroacetate as an acid catalyst (acid A), hexamethyldisilazane as a silicon compound A, and PGMEA as an organic solvent. The procedure was the same as Example 1 except that the film forming chemical solution was obtained. Hexamethyldisilazane contained in the chemical solution of this example is silicon compound B that was not consumed in the reaction for obtaining acid A, and the component functions as silicon compound A. As shown in Table 3, the evaluation results showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 58
All were the same as Example 57 except that a mixed solvent having a mass ratio of HFE-7100 and PGMEA of 95: 5 was used as the organic solvent in the protective film forming chemical solution. As shown in Table 3, the evaluation results showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 59
All were the same as Example 57 except that a mixed solvent having a mass ratio of CTFP and PGMEA of 95: 5 was used as the organic solvent in the protective film forming chemical solution. As shown in Table 3, the evaluation results showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 60
All were the same as in Example 57 except that a mixed solvent having a mass ratio of DCTFP and PGMEA of 95: 5 was used as the organic solvent in the protective film forming chemical solution. As shown in Table 3, the evaluation results showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 61
The acid B was the same as that of Example 58 except that trifluoromethanesulfonic acid [CF ₃ S (O ₂ ) OH] was used. As shown in Table 3, the evaluation results showed that the contact angle after the surface treatment was 80 °, which showed the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.6 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 62
All were the same as Example 61 except that a mixed solvent having a mass ratio of CTFP and PGMEA of 95: 5 was used as the organic solvent in the protective film forming chemical solution. As shown in Table 3, the evaluation results showed that the contact angle after the surface treatment was 80 °, which showed the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.6 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 63
As silicon compound B, tetramethyldisilazane [(H ₃ C) ₂ Si (H) —NH—Si (H) (CH ₃ ) ₂ ]; 1 g, trifluoroacetic acid [CF ₃ C (O) OH as acid B ] 0.1 g and PGMEA as an organic solvent: 98.9 g were mixed and reacted as shown in the following formula, whereby dimethylsilyl trifluoroacetate as an acid catalyst (acid A), tetramethyldisilazane as a silicon compound A, The same procedure as in Example 1 was conducted except that a protective film-forming chemical solution containing PGMEA as an organic solvent was obtained. Tetramethyldisilazane contained in the chemical solution of this example is silicon compound B that was not consumed in the reaction for obtaining acid A, and the component functions as silicon compound A. As shown in Table 3, the evaluation result showed that the contact angle after the surface treatment was 86 °, indicating the effect of imparting water repellency. Further, the capillary force when water was held was 0.2 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 64
All were the same as Example 63 except that the silicon compound B concentration was 10 mass%. As shown in Table 3, the evaluation result showed that the contact angle after the surface treatment was 88 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.1 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 65
All were the same as Example 63 except that a mixed solvent having a mass ratio of HFE-7100 and PGMEA of 95: 5 was used as the organic solvent in the protective film forming chemical solution. As shown in Table 3, the evaluation result showed that the contact angle after the surface treatment was 86 °, indicating the effect of imparting water repellency. Further, the capillary force when water was held was 0.2 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 66
The same procedure as in Example 65 was conducted except that trifluoromethanesulfonic acid [CF ₃ S (O ₂ ) OH] was used as the acid B. As shown in Table 3, the evaluation results showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 67
By using trimethylsilyldimethylamine [(CH ₃ ) ₃ Si—N (CH ₃ ) ₂ ] as the silicon compound B and reacting as shown in the following formula, trimethylsilyl trifluoroacetate, silicon compound as the acid catalyst (acid A) The procedure was the same as Example 63 except that a protective film-forming chemical solution containing trimethylsilyldimethylamine as A was obtained. Trimethylsilyldimethylamine contained in the chemical solution of this example is silicon compound B that was not consumed in the reaction for obtaining the acid A, and the component functions as silicon compound A. As shown in Table 3, the evaluation results showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 68
By using trimethylsilyldiethylamine [(CH ₃ ) ₃ Si—N (C ₂ H ₅ ) ₂ ] as the silicon compound B and reacting it as shown in the following formula, trimethylsilyl trifluoroacetate, silicon as an acid catalyst (acid A) The procedure was the same as Example 63 except that a protective film-forming chemical solution containing trimethylsilyldiethylamine as compound A was obtained. Trimethylsilyldiethylamine contained in the chemical solution of this example is silicon compound B that was not consumed in the reaction for obtaining the acid A, and the component functions as silicon compound A. As shown in Table 3, the evaluation results showed that the contact angle after the surface treatment was 80 °, which showed the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.6 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 69
By using butyldimethyl (dimethylamino) silane [C ₄ H ₉ Si (CH ₃ ) ₂ —N (CH ₃ ) ₂ ] as the silicon compound B and reacting it as shown in the following formula, an acid catalyst (acid A) Example 63 was the same as Example 63 except that a protective film-forming chemical solution containing butyldimethylsilyl trifluoroacetate as the silicon compound and butyldimethyl (dimethylamino) silane as the silicon compound A was obtained. Butyldimethyl (dimethylamino) silane contained in the chemical solution of this example is silicon compound B that was not consumed in the reaction for obtaining acid A, and the component functions as silicon compound A. As shown in Table 3, the evaluation result showed that the contact angle after the surface treatment was 92 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.1 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 70
As the silicon compound B, octyldimethyl (dimethylamino) silane [C ₈ H ₁₇ Si (CH ₃ ) ₂ —N (CH ₃ ) ₂ ] is used and reacted as in the following formula, whereby an acid catalyst (acid A) Example 63 was the same as Example 63 except that a protective film-forming chemical solution containing octyldimethylsilyl trifluoroacetate as the silicon compound and octyldimethyl (dimethylamino) silane as the silicon compound A was obtained. Octyldimethyl (dimethylamino) silane contained in the chemical solution of this example is silicon compound B that was not consumed in the reaction for obtaining acid A, and the component functions as silicon compound A. As shown in Table 3, the evaluation result showed that the contact angle after the surface treatment was 104 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.8 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 71
The same procedure as in Example 67 was performed except that trifluoromethanesulfonic acid [CF ₃ S (O ₂ ) OH] was used as the acid B. As shown in Table 3, the evaluation result showed that the contact angle after the surface treatment was 86 °, indicating the effect of imparting water repellency. Further, the capillary force when water was held was 0.2 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 72
The same procedure as in Example 69 was performed except that trifluoromethanesulfonic acid [CF ₃ S (O ₂ ) OH] was used as the acid B. As shown in Table 3, the evaluation result showed that the contact angle after the surface treatment was 94 °, indicating the effect of imparting water repellency. Further, the capillary force when water was held was 0.2 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 73
The same procedure as in Example 70 was performed except that trifluoromethanesulfonic acid [CF ₃ S (O ₂ ) OH] was used as the acid B. As shown in Table 3, the evaluation result showed that the contact angle after the surface treatment was 104 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.8 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 74
In the above “(2) Cleaning of silicon wafer”, a silicon wafer with a smooth thermal oxide film (Si wafer having a thermal oxide film layer with a thickness of 1 μm on the surface) is immersed in a 1 mass% hydrofluoric acid aqueous solution at room temperature for 2 minutes. Then, it was immersed in pure water for 1 min. Further, it was the same as Example 57 except that it was immersed in a 0.3 mass% hydrochloric acid aqueous solution at 98 ° C. for 1 min, then immersed in pure water at room temperature for 1 min, and then immersed in 2-propanol (iPA) for 1 min. As shown in Table 3, the evaluation result showed that the contact angle after the surface treatment was 86 °, indicating the effect of imparting water repellency. Further, the capillary force when water was held was 0.2 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 75
A silicon wafer with a smooth silicon nitride film (Si wafer having a silicon nitride layer with a thickness of 0.3 μm on the surface) was used, except that a silicon wafer with a smooth silicon nitride film was used. As shown in Table 3, the evaluation result showed that the contact angle after the surface treatment was 78 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.7 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 76
In the above “(2) Cleaning of silicon wafer”, a silicon wafer with a smooth silicon nitride film (Si wafer having a silicon nitride layer having a thickness of 0.3 μm on the surface) is immersed in a 1% by mass hydrofluoric acid aqueous solution at room temperature for 2 min. And immersed in pure water for 1 min. Furthermore, after dipping for 1 min at 98 ° C. in a mixed solution of 0.6 mass% hydrochloric acid aqueous solution and ethylene glycol at a mass ratio of 50:50, then dipping in pure water for 1 min at room temperature, then 1 min in 2-propanol (iPA). The procedure was the same as Example 75 except for immersion. As shown in Table 3, the evaluation results showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 77
All were the same as Example 75 except that a mixed solvent having a mass ratio of HFE-7100 and PGMEA of 95: 5 was used as the organic solvent in the protective film forming chemical. As shown in Table 3, the evaluation result showed that the contact angle after the surface treatment was 78 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.7 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 78
All were the same as Example 76 except that a mixed solvent having a mass ratio of HFE-7100 and PGMEA of 95: 5 was used as the organic solvent in the protective film forming chemical. As shown in Table 3, the evaluation results showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 79
The procedure was the same as Example 75 except that a smooth silicon wafer with a polysilicon film (Si wafer having a polysilicon layer with a thickness of 0.3 μm on the surface) was used. As shown in Table 3, the evaluation results showed that the contact angle after the surface treatment was 80 °, which showed the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.6 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

Example 80
The procedure was the same as Example 76, except that a smooth silicon wafer with a polysilicon film (Si wafer having a polysilicon layer with a thickness of 0.3 μm on the surface) was used. As shown in Table 3, the evaluation results showed that the contact angle after the surface treatment was 84 °, indicating the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.3 MN / m ² , and the capillary force was small. Further, the contact angle after UV irradiation was less than 10 °, and the water repellent 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 protective film forming chemical solution remained after UV irradiation.

DESCRIPTION OF SYMBOLS 1 Wafer 2 Fine uneven | corrugated pattern 3 on the wafer surface 3 Pattern convex part 4 Pattern concave part 5 Concave width 6 Convex part height 7 Convex part width 8 Cleaning liquid 9 held in the concave part 4 Aqueous system held in the concave part 4 Cleaning liquid 10 Water repellent protective film

Claims (5)

A chemical solution for forming a water-repellent protective film on at least the concave surface of the concavo-convex pattern when cleaning a wafer having a fine concavo-convex pattern on the surface and at least part of the concavo-convex pattern includes silicon,
A chemical solution for forming a protective film comprising 0.01 to 30% by mass of a silicon compound A represented by the following general formula [1] and an aprotic organic solvent.

Here, R ¹ is each independently a monovalent organic group containing a hydrocarbon group having 1 to 18 carbon atoms and a monovalent organic group containing a fluoroalkyl chain having 1 to 8 carbon atoms. X is at least one group selected from: a monovalent organic group in which the element bonded to Si is nitrogen, a monovalent organic group in which the element bonded to Si is oxygen, and , At least one group selected from halogen groups, a is an integer of 1 to 3, b is an integer of 0 to 2, and the sum of a and b is 1 to 3. The aprotic organic solvent has a solubility in 100 parts by mass of water of 5 parts by mass or more,
The protective film-forming chemical solution according to claim 1, wherein the protective film-forming chemical solution contains 50 to 99.99% by mass of the aprotic organic solvent. 3. The silicon compound A according to claim 1, wherein X in the silicon compound A is a monovalent organic group in which an element bonded to Si is nitrogen, and the protective film forming chemical contains acid A. Chemical solution for protective film formation. The protective film-forming chemical solution according to claim 1, wherein the protective film-forming chemical solution has a boiling point of 70 to 220 ° C. 5. A method for cleaning a wafer surface using the chemical solution for forming a protective film according to claim 1, wherein the surface has a fine concavo-convex pattern and at least part of the concavo-convex pattern includes silicon, and the method Is
Cleaning the wafer surface with a cleaning liquid;
Forming a water-repellent protective film on at least the concave surface of the concave-convex pattern using the protective film-forming chemical,
Removing the liquid retained on the surface of the uneven pattern from the surface of the uneven pattern;
After the step of removing the liquid, the protective film is removed by performing at least one treatment selected from irradiating the wafer surface with light, heating the wafer, and exposing the wafer to ozone. And a method for cleaning a wafer surface having a fine uneven pattern on the surface.

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