TW201303002A - Liquid Chemical for Forming Water Repellent Protecting Film, and Process for Cleaning Wafers Using the Same - Google Patents

Abstract

A liquid chemical for forming a water repellent protecting film on a wafer having at its surface an uneven pattern and containing at least one kind of element selected from the group consisting of titanium, tungsten, aluminum, copper, tin, tantalum and ruthenium at surfaces of recessed portions of the uneven pattern, the water repellent protecting film being formed at least on the surfaces of the recessed portions. The liquid chemical is characterized by including: a water repellent protecting film forming agent; and water, and characterized in that the water repellent protecting film forming agent is at least one selected from compounds represented by the following general formula [1] and salt compounds thereof and that the concentration of the water relative to the total quantity of a solvent contained in the liquid chemical is not smaller than 50 mass %.

Description

Water-repellent protective film forming liquid and cleaning method using the same

The present invention relates to a cleaning technique of a substrate (wafer) in the manufacture of a semiconductor element or the like.

In the semiconductor components for networking or digital home appliances, further high performance, high functionality, or low power consumption have been demanded. Therefore, the circuit pattern is being miniaturized, and as the miniaturization progresses, the pattern of the circuit pattern collapses. In the manufacture of a semiconductor element, a cleaning step for removing fine particles or metal impurities is often employed, and as a result, the cleaning step accounts for 3 to 40% of the entire semiconductor manufacturing step. In the cleaning step, when the aspect ratio of the pattern in which the semiconductor element is miniaturized becomes high, the phenomenon in which the pattern collapses when the gas-liquid interface passes through the pattern after washing or rinsing is a pattern collapse.

Patent Document 1 discloses a technique for suppressing pattern collapse, which discloses a technique in which a cleaning liquid is replaced with water to 2-propanol before a gas-liquid interface passes through a pattern. However, it can be said that there is a limit, for example, the aspect ratio of the pattern that can be handled is 5 or less.

Further, in Patent Document 2, as a method of suppressing pattern collapse, a technique for a resist pattern is disclosed. This method is a method of suppressing pattern collapse by reducing the capillary force to the limit.

However, the technique disclosed above is directed to a resist pattern, and the resist itself is modified, and finally, it can be removed together with the resist. Therefore, it is not necessary to envisage a method of removing the treated agent after drying, and it is not applicable. For the purpose.

Further, Patent Document 3 discloses a cleaning method in which a pair of oxidation or the like is used. The surface of the wafer having the uneven pattern formed by the film containing ruthenium is surface-modified, and a water-repellent protective agent or a decane coupling agent is used to form a water-repellent protective film on the surface to reduce the capillary force and prevent the chip from collapsing.

Further, Patent Documents 4 and 5 disclose a technique for preventing pattern collapse by using a treatment liquid containing a decylating agent represented by N,N-dimethylaminotrimethylnonane and a solvent to perform hydrophobic treatment. .

Prior technical literature Patent literature

Patent Document 1: Japanese Patent Laid-Open Publication No. 2008-198958

Patent Document 2: Japanese Patent Laid-Open No. Hei 5-299336

Patent Document 3: Japanese Patent No. 4403202

Patent Document 4: Japanese Patent Laid-Open Publication No. 2010-129932

Patent Document 5: International Publication No. 10/47196

The present invention relates to a cleaning technique of a substrate (wafer) for improving the manufacturing yield of an element having a circuit pattern which is fine and has a relatively high aspect ratio in the manufacture of a semiconductor element or the like, and particularly relates to an improvement of the substrate (wafer) which is easy to cause The washing step of disintegrating the concave-convex pattern of the wafer having the uneven pattern on the surface is a purpose of the aqueous liquid protective film forming chemical liquid or the like. Conventionally, wafers containing germanium on the surface have been used as the wafers, but with the diversification of patterns, the use of a group selected from the group consisting of titanium, tungsten, aluminum, copper, tin, antimony, and antimony has begun. A wafer of at least one element (hereinafter sometimes referred to as "metal wafer" or simply "wafer"). However, as in the above metal system In the case where a wafer having a reactive functional group such as a stanol-based substrate is not sufficiently formed on the surface of the wafer, even if the treatment liquid and the treatment method described in Patent Documents 3 to 5 are used, the water repellency preventing the collapse of the pattern cannot be formed. The protective film has a problem that the pattern cannot be prevented from collapsing. Further, since the treatment liquids described in Patent Documents 3 to 5 are flammable liquids containing an organic solvent, there is room for improvement in terms of safety and environmental load. An object of the present invention is to provide a protective film forming chemical liquid which is formed into a water-repellent protective film and which is used to form a liquid retaining film in the concave portion by forming a water-repellent protective film on at least a concave portion surface of the metal-based wafer. The interaction of the surface of the recess is weakened, and the cleaning step which easily causes the pattern to collapse is improved.

In addition, the present invention relates to a cleaning technique of a substrate (wafer) for improving the manufacturing yield of an element having a circuit pattern which is fine and has a relatively high aspect ratio, particularly in the manufacture of a semiconductor element, and the like. A method of cleaning a wafer for removing a water-repellent protective film forming liquid for the purpose of a cleaning step of causing a concave-convex pattern collapse of a wafer having a concave-convex pattern on the surface. In the case of using the treatment liquid and the treatment method described in Patent Documents 3 to 5, the treatment liquid absorbs moisture of the environment (outside gas) during the treatment. Further, since water or an alcohol (for example, 2-propanol: iPA or the like) is used in the washing step, the treatment liquid may be brought into contact with or mixed with water or alcohol, and as a result, the water repellency of the treatment liquid may be lowered. Happening. Therefore, the above-mentioned treatment liquid is in a state of being discarded without being reused. A further object of the present invention is to provide a cleaning method capable of economically cleaning a wafer by reusing a chemical solution for forming a protective film.

Pattern collapse occurs when the gas-liquid interface passes through the pattern while the wafer is drying. It can be said that the reason is that a residual liquid level difference occurs between the relatively high and vertical portions of the pattern, and the capillary force acting on the pattern causes a difference.

Therefore, if the capillary force is reduced, it is expected that the difference in capillary force caused by the difference in the level of the residual liquid is lowered, and the pattern collapse is eliminated. The magnitude of the capillary force is an absolute value of P obtained by the following formula. According to this formula, when γ or cos θ is decreased, it is expected that the capillary force can be reduced.

P = 2 × γ × cos θ / S (wherein γ is the surface tension of the liquid held in the concave portion, θ is the contact angle between the surface of the concave portion and the liquid held in the concave portion, and S is the width of the concave portion)

<First Aspect of the Invention>

The first aspect of the present invention is a chemical solution for forming a water-repellent protective film (hereinafter, referred to as "a protective liquid for forming a protective film" or simply as a "medicine liquid"), which is characterized in that it is formed on the surface. a concave-convex pattern, wherein the surface of the concave portion of the concave-convex pattern contains at least the surface of the concave portion of the wafer selected from at least one of the group consisting of titanium, tungsten, aluminum, copper, tin, antimony, and antimony to form a water-repellent protection a film (hereinafter sometimes referred to simply as "protective film"); the chemical liquid contains a water-repellent protective film forming agent (hereinafter sometimes referred to as "protective film forming agent") and water; and the water-repellent protective film forming agent is It is at least one selected from the group consisting of a compound represented by the following formula [1] and a salt compound thereof; and the concentration of water contained in the above-mentioned chemical solution is 50% by mass based on the total amount of the solvent. on.

(In the formula [1], R ¹ is a monovalent hydrocarbon group in which a part or all of hydrogen elements may be substituted by a fluorine element and has a carbon number of 1 to 18, and R ^{2 is} independently of each other to contain a part or all of hydrogen elements via a fluorine element. a monovalent organic group substituted with a hydrocarbon group of 1 to 18, a being an integer of 0 to 2)

By using the protective film forming agent represented by the above formula [1], a water-repellent protective film can be formed on at least the surface of the concave portion of the metal-based wafer. In the protective film forming agent, a P-OH group and/or a P=O group (hereinafter, collectively referred to as "functional portion") may have an affinity for a substance containing the above metal element. Here, the affinity means that adsorption is carried out between a surface of a substance containing the metal element and a functional part of the protective film forming agent by a vanguard force or an electrostatic interaction, and/or The surface of the substance reacts with the functional portion of the protective film forming agent to form a chemical bond, and is adsorbed. Further, R ¹ is a hydrophobic portion of the protective film forming agent, and when the protective film forming agent is adsorbed to the metal element of the metal wafer, the hydrophobic portion is arranged outward from the surface of the wafer, and as a result, the The surface of the wafer is hydrophobic.

The metal-based wafer is characterized in that at least one element selected from the group consisting of titanium, tungsten, aluminum, copper, tin, antimony, and antimony is contained on the surface of the concave portion of the concave-convex pattern, and preferably contains titanium, Among the groups of aluminum and bismuth The at least one element of the composition is preferably one containing at least one of titanium and bismuth, and particularly preferably containing titanium. In the case where the surface of the concave portion of the concave-convex pattern contains a germanium element wafer, a large amount of stanol groups (SiOH groups) are present on the surface, and the stanol group becomes a reaction point with the decane coupling agent, so that a water-repellent protective film is easily formed on the surface of the concave portion. . On the other hand, in the metal-based wafer, the number of reaction points corresponding to the stanol group on the surface is small, and it is difficult to form a protective film by using a compound such as a decane coupling agent. Further, in the present invention, a wafer having a concavo-convex pattern on its surface is a wafer which is in a state in which a concave-convex pattern is formed on the surface by etching or imprinting. In addition, even if other processors such as metal wiring are applied to the wafer, any object having a concave-convex pattern on the surface thereof may be used.

The water-repellent protective film forming agent is preferably one which is soluble in water. When the solubility is too small, it is difficult to sufficiently contain the water-repellent protective film forming agent in the aqueous solution for forming a water-repellent protective film, which is not preferable. On the other hand, if the solubility is too large, it is difficult to impart sufficient water repellency to the surface of the metal wafer, which is not preferable. Therefore, the water-repellent protective film forming agent has a solubility in water of preferably 5 to 100,000 ppm by mass, more preferably 10 to 50,000 ppm by mass, still more preferably 15 to 10,000 ppm by mass.

Further, the water-repellent protective film forming agent is preferably at least one selected from the group consisting of a compound represented by the following formula [2] and a salt compound thereof.

(In the formula [2], R ³ is a monovalent hydrocarbon group in which a part or all of the hydrogen element may be substituted by a fluorine element and has a carbon number of 1 to 18)

Further, the water repellent protective film forming agent is more preferably a compound represented by the above formula [2].

The protective film forming chemical solution of the present invention is used by replacing the cleaning liquid with the chemical liquid in the cleaning step of the metal-based wafer. Further, the chemical liquid to be replaced may be replaced with another cleaning liquid.

As described above, the cleaning liquid is replaced with the protective film forming chemical liquid, and the protective film can be formed on at least the concave portion surface of the concave-convex pattern while the chemical liquid is held in at least the concave portion of the concave-convex pattern. The protective film of the present invention is not necessarily formed continuously, and it is not necessarily uniformly formed, but it is more preferably continuously and uniformly formed in order to impart more excellent water repellency.

In the present invention, the protective film refers to a water-repellent protective film which is formed on at least the concave portion by holding the protective film forming chemical solution in at least the concave portion during cleaning of the metal-based wafer. The protective film is formed of a water-repellent protective film forming agent and/or a reactant thereof, and is a film that reduces the wettability of the surface of the wafer, that is, a film that imparts water repellency. In the present invention, the term "water repellency" means that the surface energy of the surface of the article is lowered, and interaction (such as hydrogen bonding, intermolecular force, etc.) is weakened between water or other liquid and the surface of the article (interface). In particular, the effect of weakening the interaction of water is large, but there is also an effect of weakening the interaction between a mixture of water and a liquid other than water or a liquid other than water. By the weakening of the interaction, the contact angle of the liquid relative to the surface of the article can be increased.

Moreover, the method for cleaning a wafer of the present invention is characterized in that the wafer is a watch The surface is formed with a concave-convex pattern, and the concave portion surface of the concave-convex pattern contains at least one element selected from the group consisting of titanium, tungsten, aluminum, copper, tin, antimony, and antimony; the method includes at least: a concave-convex pattern a step of forming a water-repellent protective film for retaining a protective film forming liquid in at least a concave portion, a drying step of removing the liquid from the concave-convex pattern by drying, and a film removing step of removing the protective film; and the protective film forming chemical liquid contains a water-repellent protective film forming agent and water; the water-repellent protective film forming agent is at least one selected from the group consisting of the compound represented by the above formula [1] and a salt compound thereof; and the water contained in the liquid solution is relative to the solvent The concentration of the amount is 50% by mass or more.

In the present invention, when the liquid is removed from the concave portion, that is, when the drying is performed, the protective film is formed on at least the surface of the concave portion of the concave-convex pattern. Therefore, the capillary force acting on the concave portion is reduced, and the drying is less likely to occur. The pattern collapsed. Further, the protective film is removed after the drying step.

Moreover, it is preferable to include an aqueous washing step of holding the aqueous cleaning liquid in at least the concave portion of the concave-convex pattern before the water-repellent protective film forming step.

Furthermore, it is preferable that the water-repellent protective film forming agent is at least one selected from the group consisting of the compound represented by the above formula [2] and a salt compound thereof, and more preferably the water-repellent protective film forming agent is selected. At least one of the compounds represented by the above formula [2].

<Second view of the present invention>

A second aspect of the present invention is a method for cleaning a wafer, characterized in that a surface of the wafer is formed with a concave-convex pattern, and a surface of the concave portion of the concave-convex pattern is selected from the group consisting of titanium, tungsten, aluminum, copper, tin, and antimony. And a wafer of at least one of the groups of the group (hereinafter referred to as "metal wafer" or simply "wafer"); the method includes at least a water-repellent protective film forming step, A water-repellent protective film forming chemical solution for forming a water-repellent protective film forming agent for forming a water-repellent protective film (hereinafter sometimes referred to as "protective film") on the surface of the wafer (hereinafter, it may be referred to as " The protective film forming chemical solution (or simply "medicine liquid") is supplied to at least the concave portion of the wafer, and a water-repellent protective film is formed on the surface of the concave portion; and the remaining water-repellent property generated in the water-repellent protective film forming step is formed. The chemical solution for forming a protective film and/or the chemical solution for forming a water-repellent protective film after the step of forming the water-repellent protective film are recovered and reused, and the water-repellent protective film forming agent is a compound having no hydrolyzable functional group.

The metal-based wafer includes at least one element selected from the group consisting of titanium, tungsten, aluminum, copper, tin, antimony, and antimony, and preferably contains titanium selected from the group consisting of titanium, tungsten, aluminum, copper, tin, antimony, and antimony. The at least one element selected from the group consisting of tungsten, aluminum, and tantalum is more preferably one containing at least one of titanium, tantalum, and tungsten, and particularly preferably containing titanium. In the case where the surface of the concave portion of the concave-convex pattern contains a germanium element wafer, a large amount of stanol groups (SiOH groups) are present on the surface, and the stanol group becomes a reaction point with the decane coupling agent, so that a water-repellent protective film is easily formed on the surface of the concave portion. . On the other hand, in a metal-based wafer, the reaction point corresponding to a stanol group on the surface is small, and it is difficult to benefit. A protective film is formed using a compound such as a decane coupling agent. Further, in the present invention, a wafer having a concavo-convex pattern on its surface is a wafer which is in a state in which a concave-convex pattern is formed on the surface by etching or imprinting. In addition, even if other processing such as metal wiring is performed on the wafer, any object having a concave-convex pattern on the surface thereof may be used.

The protective film forming chemical solution is used by replacing the cleaning liquid with the chemical liquid in the cleaning step of the metal-based wafer. Further, the chemical liquid to be replaced may be replaced with another cleaning liquid.

As described above, the cleaning liquid is replaced with the protective film forming chemical liquid, and the protective film can be formed on at least the concave portion surface of the concave-convex pattern while the chemical liquid is held in at least the concave portion of the concave-convex pattern. The protective film of the present invention is not necessarily formed continuously, and it is not necessarily uniformly formed, but it is more preferably continuously and uniformly formed in order to impart more excellent water repellency.

In the present invention, the protective film refers to a water-repellent protective film which is formed on at least the concave portion by holding the protective film forming chemical solution in at least the concave portion during cleaning of the metal-based wafer. The protective film is formed of a water-repellent protective film forming agent and/or a reactant thereof, and is a film that reduces the wettability of the surface of the wafer, that is, a film that imparts water repellency. In the present invention, the term "water repellency" means that the surface energy of the surface of the article is lowered, and interaction (such as hydrogen bonding, intermolecular force, etc.) is weakened between water or other liquid and the surface of the article (interface). In particular, the effect of weakening the interaction of water is large, but there is also an effect of weakening the interaction between a mixture of water and a liquid other than water or a liquid other than water. By the weakening of the interaction, the contact angle of the liquid relative to the surface of the article can be increased.

When the chemical liquid is held in at least the concave portion of the concave-convex pattern, the chemical liquid comes into contact with the outside air, so that it is easy to mix the water into the chemical liquid. Since the water-repellent protective film forming agent used in the present invention is a compound having no hydrolyzable functional group, it is not hydrolyzed by the water to be mixed, and the performance is lowered. Therefore, the above chemical solution can maintain the performance after the water-repellent protective film forming step. Therefore, the remaining portion of the chemical liquid generated in the water-repellent protective film forming step or the chemical liquid after the water-repellent protective film forming step can be reused if it is recovered.

The wafer on which the uneven pattern is formed on the surface is often washed with a washing liquid containing water and/or alcohol. When the washing liquid used herein is mixed or brought into contact with the chemical liquid, the amount of the washing liquid is more than the case where the external gas is mixed into the chemical liquid. Therefore, the method for cleaning a wafer of the present invention is particularly effective in the process of the step of washing the surface of the wafer with a washing liquid containing water and/or alcohol before the step of forming the water-repellent protective film.

In addition, the water-repellent protective film forming agent contained in the chemical solution for forming a water-repellent protective film used in the method for cleaning a wafer of the present invention is preferably selected from the following general formulas [1] to [6]. At least one of a compound and a salt compound thereof.

(In the formula [1], R ¹ is a monovalent hydrocarbon group in which a part or all of hydrogen elements may be substituted by a fluorine element and has a carbon number of 1 to 18, and R ^{2 is} independently of each other to contain a part or all of hydrogen elements via a fluorine element. a monovalent organic group substituted with a hydrocarbon group of 1 to 18, a being an integer of 0 to 2) (In the formula [2], R ³ is a monovalent hydrocarbon group in which a part or all of hydrogen elements may be substituted by a fluorine element and has a carbon number of 1 to 18, R ⁴ is a hydrogen group, or a part or all of hydrogen elements may pass through a fluorine element a substituted monovalent hydrocarbon group having 1 to 8 carbon atoms. [Chemical 5](R ⁵ ) _b -NH _3b [3] (In the formula [3], R ⁵ is a part or all of hydrogen element which may pass through a fluorine element The substituted carbon number is a monovalent hydrocarbon group of 1 to 18, and b is an integer of 1 to 3) [6] R ⁶ (X) _c [4] (In the formula [4], X is independently a thiol group or an aldehyde, respectively. a group, c is an integer of 1 to 6, and R ⁶ is a part or all of a hydrogen element which may be substituted by a fluorine element and has a monovalent hydrocarbon group having 1 to 18 carbon atoms, which is a hydrogen element or a fluorine element substituted by an X group) (In the formula [5], R ⁷ is a monovalent hydrocarbon group in which a part or all of the hydrogen element may be substituted by a fluorine element and has a carbon number of 1 to 18) (In the formula [6], R ⁸ is a monovalent hydrocarbon group in which a part or all of the hydrogen element may be substituted by a fluorine element and has a carbon number of 1 to 18)

By using the protective film forming agent represented by the above general formulas [1] to [6], a water-repellent protective film can be formed on at least the surface of the recessed portion of the above-described metal-based wafer. a P-OH group, a P=O group, a C(O)OR ⁴ group, an NH _3-b group, an X group, a -CONHOH group, or a functional group of the following formula [9] in the protective film forming agent (hereinafter, These are collectively referred to as "functional parts" and have an affinity for a substance containing the above metal element. Here, the affinity means that it is adsorbed and/or borrowed by acting between a surface of a substance containing the metal element and a functional part of the protective film forming agent by a van der Waals force or an electrostatic interaction or the like. The surface of the substance is reacted with a functional portion of the protective film forming agent to form a chemical bond and adsorbed. Further, R ¹ , R ³ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are hydrophobic portions of the protective film forming agent, and when the protective film forming agent is adsorbed to the metal element of the metal wafer, the hydrophobic portion Arranged from the surface of the wafer toward the outside, as a result, the surface of the wafer can be made hydrophobic.

Further, the water-repellent protective film forming agent is preferably at least one selected from the group consisting of a compound represented by the following general formulas [7] and [8], and a salt compound thereof.

(In the formula [7], R ⁹ is a monovalent hydrocarbon group in which a part or all of the hydrogen element may be substituted by a fluorine element and has a carbon number of 1 to 18) [11] R ¹⁰ -NH ₂ [8] (Formula [8] Wherein R ¹⁰ is a monovalent hydrocarbon group having a carbon number of 1 to 18 which may be substituted by a fluorine element of a part or all of the hydrogen element)

Since the protective film formed by the protective film forming chemical solution of the present invention is excellent in water repellency, a concave-convex pattern can be formed on the surface, and the surface of the concave portion of the concave-convex pattern is selected from the group consisting of titanium, tungsten, aluminum, copper, tin, antimony, The interaction between the liquid held in the concave portion and the surface of the concave portion of the wafer of at least one of the groups of the group is weakened, and the pattern collapse preventing effect can be exhibited. When this chemical liquid is used, the washing step in the method of manufacturing a wafer having a concave-convex pattern on the surface can be improved without lowering the yield. Therefore, the method for producing a wafer having a concave-convex pattern on the surface by using the protective film forming chemical solution of the present invention is highly productive. Further, the protective film forming liquid of the present invention is a water contained in the chemical liquid relative to the solvent When the concentration of the total amount is 50% by mass or more, when the content is a nonaqueous solvent, the content is a small amount (50% by mass or less based on the total amount of the solvent contained in the chemical solution), and thus it is safe. A more excellent liquid, a liquid with a smaller environmental load. Moreover, since the chemical solution for forming a protective film of the present invention can be used repeatedly, if the chemical liquid is used, the wafer can be economically cleaned.

Further, in the wafer cleaning method of the present invention, the water-repellent protective film forming chemical liquid can be used repeatedly, so that the wafer can be economically cleaned.

<First Aspect According to the Invention>

First, the present invention will be described in detail based on the first aspect.

Before the surface treatment using the chemical solution for forming a protective film of the present invention, it is usually the case that the pretreatment steps listed below are often carried out.

a pretreatment step 1 of forming a surface of the wafer with a concave-convex pattern; a pretreatment step 2 of washing the surface of the wafer with an aqueous cleaning solution; and replacing the aqueous cleaning solution with a different aqueous cleaning solution The pretreatment step 3 of the cleaning solution A (hereinafter, abbreviated as "washing liquid A").

Furthermore, there are cases where the pre-processing step 2 or the pre-processing step 3 is omitted.

In the above pretreatment step 1, the pattern forming method is first, applying a resist on the surface of the wafer, and thereafter exposing the resist via a resist mask, and exposing the exposed resist or not The exposed resist is etched away to form a resist having a desired concavo-convex pattern. Further, by pressing the patterned mold against the resist, a resist having a concavo-convex pattern can also be obtained. The wafer is then etched. At this time, the surface of the wafer corresponding to the concave portion of the resist pattern is selectively etched. most Thereafter, if the resist is peeled off, a wafer having a concavo-convex pattern can be obtained.

By the pretreatment step described above, a concave-convex pattern is formed on the surface, and at least one element selected from the group consisting of titanium, tungsten, aluminum, copper, tin, antimony, and antimony is contained on the surface of the concave portion of the concavo-convex pattern. Wafer (metal wafer). Examples of the metal-based wafer include a substance containing at least one element selected from the group consisting of titanium, tungsten, aluminum, copper, tin, antimony, and antimony (hereinafter, referred to as "metal-based substance" The layer is coated with a wafer, a wafer containing a plurality of components including germanium and/or germanium dioxide (SiO ₂ ), a silicon carbide wafer, a sapphire wafer, various compound semiconductor wafers, a plastic wafer, or the like. On the surface, a multilayer film is formed on the wafer, at least one of which is a layer of the above-described metal-based substance, and the above-described uneven pattern forming step is performed in a layer including the metal-based substance layer. Further, when the concave-convex pattern is formed, at least one of the surfaces of the concave-convex pattern surface of the concave-convex pattern is the metal-based material.

Examples of the metal-based material include titanium nitride, titanium oxide, and titanium; and tungsten or tungsten oxide; and aluminum; As the material containing copper element, there are copper, copper oxide, etc.; as a substance containing tin element, tin, acidified tin, etc.; as a substance containing a bismuth element, there are ruthenium, ruthenium oxide, ruthenium nitride, etc.; As a substance containing a cerium element, there are cerium, cerium oxide, and the like.

Further, the protective film may be formed on the surface of the metal-based material for a wafer including a plurality of components containing the metal-based substance. As a wafer including the plurality of components, it is also included in at least one part of the surface of the recess When the metal-based substance is formed, or when a concave-convex pattern is formed, at least one of the surfaces of the concave portion becomes the metal-based substance. Further, the protective film formed by the chemical solution of the present invention may be at least the surface of the metal-based substance portion of the uneven pattern. Therefore, the protective film may be formed on at least one of the surfaces of the recessed portions of the metal-based wafer.

In addition, since the chemical solution for forming a protective film of the present invention is easy to form an excellent water-repellent protective film on the surface of the article containing the titanium element on the surface, the wafer is preferably formed with a concave-convex pattern on the surface and a concave portion of the concave-convex pattern. A wafer containing titanium on its surface.

Examples of the aqueous cleaning solution used in the pretreatment step 2 include water or at least one of an organic solvent, hydrogen peroxide, ozone, an acid, a base, and a surfactant prepared by mixing in water. The aqueous solution (for example, the water content is 10% by mass or more).

Further, in the pretreatment step 2, the replacement with the aqueous cleaning solution may be carried out twice or more. The aqueous cleaning solution used at this time may be different.

In the pretreatment step 2, after the surface is washed with the aqueous cleaning solution, the water-based cleaning solution is directly removed by drying or the like, or the water-based cleaning solution is replaced with water, and then the water is removed by drying or the like. The width of the concave portion is small, and the longitudinal and lateral directions of the convex portion are relatively large, and the pattern collapse is likely to occur. This concave-convex pattern is defined as described in FIGS. 1 and 2 . Fig. 1 is a view showing an example of a schematic view when a wafer 1 having a surface having a concave-convex pattern 2 is formed by stereoscopic observation, and Fig. 2 is a view showing a portion of the a-a' cross section of Fig. 1. The width 5 of the concave portion is represented by the interval between the convex portion 3 and the convex portion 3 as shown in Fig. 2, 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. The pattern collapse in the washing step is likely to occur when the width of the concave portion is 70 nm or less, particularly 45 nm or less, and the aspect ratio is 4 or more, particularly 6 or more.

In the present invention, the cleaning method of the wafer is not particularly limited as long as the chemical liquid cleaning liquid can be held in at least the concave portion of the concave-convex pattern of the wafer. As a method of cleaning the wafer, a wafer in which the wafer is held at a substantially horizontal level and rotated to supply a liquid toward the vicinity of the center of rotation, and the wafer is washed one by one by washing, or a single sheet method may be used. A plurality of wafers are immersed in a washing tank to wash the batch. In addition, the form of the chemical liquid or the cleaning liquid when the chemical liquid or the cleaning liquid is supplied to at least the concave portion of the concave-convex pattern of the wafer is not particularly limited as long as it is liquid when held in the concave portion. For example, there are liquids, vapors, and the like.

The cleaning solution A used in the pretreatment step 3 means an organic solvent, a mixture of the organic solvent and the aqueous cleaning solution, and at least one of an acid, a base, and a surfactant mixed with the cleaning liquid. .

Examples of the organic solvent which is one of preferable examples of the cleaning liquid A include hydrocarbons, esters, ethers, ketones, solvents containing halogen elements, anthraquinone solvents, alcohols, and polyols. A derivative, a solvent containing a nitrogen element, or the like.

Further, from the viewpoint of cleanliness, the cleaning liquid A is preferably an organic solvent, a mixture of water and an organic solvent. In addition, when the organic solvent contains a water-soluble organic solvent (having a solubility of 5 parts by mass or more based on 100 parts by mass of water), it is preferably replaced with an aqueous cleaning solution.

Further, in the pretreatment step 3, the replacement with the cleaning solution A can be performed twice. on. In other words, the aqueous cleaning solution used in the pretreatment step 2 may be replaced with the first cleaning liquid A, and then replaced with a plurality of cleaning liquids A different from the cleaning liquid A, and then replaced with the above-mentioned cleaning liquid A. A protective film forming drug solution.

In the case where the aqueous cleaning solution used in the pretreatment step 2 can be directly replaced with the protective liquid for forming the protective film, the replacement by the cleaning liquid A may be omitted (pretreatment step 3). Since the chemical solution for forming a protective film of the present invention contains water, the replacement by the above-mentioned cleaning liquid A can be easily omitted (pretreatment step 3), and as a result, the steps can be simplified.

FIG. 3 is a schematic view showing a state in which the protective film forming chemical liquid 8 is held in the concave portion 4 in the protective film forming step. The wafer of the schematic diagram of Fig. 3 represents one of the a-a' sections of Fig. 1. At this time, the surface is dialed by the formation of a protective film on the surface of the concave portion 4.

The water-repellent protective film forming agent contained in the chemical solution for forming a water-repellent protective film to be used in the method for cleaning a wafer of the present invention is selected from the compound represented by the above formula [1] and a salt compound thereof. At least one.

The hydrocarbon group contained in R ² of the above formula [1] may, for example, be an alkyl group, an alkylene group or a hydrogen atom which is partially or wholly replaced by a fluorine element.

Further, R ^{2 is} preferably -OR ⁴ (R ⁴ is a hydrocarbon group having 1 to 18 carbon atoms). Further, when the carbon number of R ⁴ is from 1 to 8, particularly from 1 to 4, more excellent water repellency can be imparted, which is preferable. Further, R ^{4 is} preferably a linear alkyl group.

Furthermore, the water-repellent protective film forming agent is preferably a compound represented by the above formula [2] and a salt compound thereof, which is selected from the above formula [1] and has a water repellency. At least one of them.

Examples of R ¹ and R ^{3 in the} above formulas [1] and [2] include, for example, an alkyl group, a phenyl group, a hydrogen atom of a phenyl group substituted by an alkyl group, a naphthyl group, and a hydrogen element partially or wholly of one or more of the hydrocarbon groups. Substituted by fluorine element, etc.

Further, when the carbon numbers of R ¹ and R ^{3 in} the above formulas [1] and [2] are 2 to 16, particularly 4 to 14, and further 6 to 14, more excellent water repellency can be imparted, so that good. Further, the hydrocarbon group in which a part or all of the hydrogen element described above may be substituted with a fluorine element is preferably an alkyl group, and more preferably a linear alkyl group. When the hydrocarbon group is a linear alkyl group, when the protective film is formed, the hydrophobic portion of the protective film forming agent is easily aligned in the vertical direction with respect to the surface of the protective film, and the water repellency imparting effect is further improved. good. Further, in order to impart more excellent water repellency, R ¹ and R ^{3 of the} above formulas [1] and [2] are preferably a hydrocarbon group in which a part or all of hydrogen elements are substituted with a fluorine element.

The protective film forming agent may be a salt compound of the compound represented by the above formulas [1] and [2], for example, an ammonium salt or an amine salt.

Further, the concentration of the protective film forming agent in the protective film forming chemical solution is preferably 0.0005 to 2% by mass based on the total amount of the chemical liquid. When it is less than 0.0005 mass%, the water-repellent imparting effect tends to be insufficient, and if it exceeds 2 mass%, it tends to be less likely to be dissolved in the solvent contained in the above-mentioned chemical solution. Further, it is preferably 0.001 to 1% by mass, particularly preferably 0.0015 to 0.8% by mass.

Further, the chemical solution for forming a protective film may contain a solvent other than water. As the solvent, an organic solvent can be used and mixed in water at a concentration equal to or lower than the saturated solubility of water.

As the organic solvent, for example, a hydrocarbon, an ester, an ether, a ketone, a solvent containing a halogen element, an anthraquinone solvent, a lactone solvent, a carbonate solvent, an alcohol, a derivative of a polyhydric alcohol, or the like can be used. A solvent containing nitrogen or a mixture thereof. Examples of the hydrocarbons include toluene, benzene, xylene, hexane, heptane, and octane; and examples of the ester include ethyl acetate, propyl acetate, butyl acetate, and ethyl acetate. Etc.; as an example of the above ethers, there are diethyl ether, dipropyl ether, dibutyl ether, tetrahydrofuran, two Examples of the ketones include acetone, acetamidine acetone, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, and cyclohexanone; and examples of the solvent containing the halogen element, Perfluorooctane, perfluorodecane, perfluorocyclopentane, perfluorocyclohexane, hexafluorobenzene, etc., perfluorocarbon, 1,1,1,3,3-pentafluorobutane, octafluorocyclopentane Hydrogen fluoride such as alkane, 2,3-dihydro decafluoropentane, Zeorora H (manufactured by ZEON, Japan), methyl perfluoroisobutyl ether, methyl perfluorobutyl ether, ethyl perfluorobutyl ether, ethyl all Hydrofluoroether such as fluoroisobutyl ether, Asahiklin AE-3000 (manufactured by Asahi Glass), Novec HFE-7100, Novec HFE-7200, Novec 7300, Novec 7600 (all manufactured by 3M), chlorocarbon such as tetrachloromethane, chloroform, etc. Hydrochlorocarbon, chlorofluorocarbon such as dichlorodifluoromethane, 1,1-dichloro-2,2,3,3,3-pentafluoropropane, 1,3-dichloro-1,1,2,2, Hydrochlorofluorocarbons such as 3-pentafluoropropane, 1-chloro-3,3,3-trifluoropropene, 1,2-dichloro-3,3,3-trifluoropropene, perfluoroether, perfluoropolyether Examples of the solvent of the above-mentioned fluorene are dimethyl hydrazine or the like; and examples of the solvent of the above lactone include γ-butyrolactone, γ-valerolactone, γ-caprolactone, γ- Lactone, γ-octanolactone, γ-decalactone, γ-decalactone, γ-undecalactone, γ-dodecanolactone, δ-valerolactone, δ-caprolactone, δ-xin Lactone, δ-decalactone, δ-decalactone, δ-undecalactone, δ-dodecanolactone, ε-caprolactone, etc.; as an example of the above carbonate-based solvent, there is dimethyl carbonate , ethyl methyl carbonate, diethyl carbonate, propylene carbonate, etc.; as an example of alcohol, there are methanol, ethanol, propanol, butanol, ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, triethylene glycol, tripropylene glycol, tetraethylene glycol, tetrapropylene glycol, glycerin Etc.; as examples of the above derivatives of the polyol, there are ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethyl Glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl Ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monopropyl ether, tetraethylene glycol Butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether , tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether, tetrapropylene glycol monomethyl ether, butanediol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether , ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol diacetate, diethylene glycol dimethyl ether, diethylene glycol Ethyl methyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, diethylene glycol dibutyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethyl Glycol monobutyl ether acetate, diethylene glycol diacetate, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol butyl methyl ether, triethyl Glycol monomethyl ether acetate, triethylene glycol monoethyl ether acetate, triethylene glycol monobutyl ether acetate, triethylene glycol diacetate, tetraethylene glycol Methyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, tetraethylene glycol monomethyl ether acetate, tetraethylene glycol monoethyl ether acetate, tetraethylene glycol monobutyl ether acetate, Tetraethylene glycol diacetate, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dibutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, propylene glycol diacetic acid Ester, dipropylene glycol dimethyl ether, dipropylene glycol methyl propyl ether, dipropylene glycol diethyl ether, dipropylene glycol dibutyl ether, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, dipropylene glycol monobutyl ether Acid ester, dipropylene glycol diacetate, tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, tripropylene glycol dibutyl ether, tripropylene glycol monomethyl ether acetate, tripropylene glycol monoethyl ether acetate, tripropylene glycol monobutyl ether Acid ester, tripropylene glycol diacetate, tetrapropylene glycol dimethyl ether, tetrapropylene glycol monomethyl ether acetate, tetrapropylene glycol diacetate, butanediol dimethyl ether, butanediol monomethyl ether acetate, butyl Diol diacetate, triacetin, etc.; as a solvent containing nitrogen For example, there are methotrexate, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, diethylamine, triethylamine, Pyridine, etc.

Further, in consideration of the protective film forming ability of the protective film forming chemical solution, the solvent contained in the chemical liquid is preferably water, or an ester, an ether, a ketone or a polyol having no hydroxyl group is mixed in water. a mixture of derivatives. Further, in consideration of the solubility in water, the solvent to be mixed in water is preferably a derivative of a polyol, and when a derivative of a polyol having no hydroxyl group is used, a protective film for forming a protective film is formed. It can be higher, so it is especially good. Further, the protective film forming agent of the alcohol or the polyol derivative having a hydroxyl group is excellent in solubility. Therefore, when the solvent is used as the solvent contained in the chemical solution, the protective film forming agent can be dissolved at a high concentration, and a chemical solution having a high protective film formation property can be easily obtained. Therefore, the solvent can be used as the above. The solvent contained in the liquid.

Further, when the amount of water contained in the chemical liquid increases, the firing point of the chemical liquid tends to increase, and as a result, the risk of the chemical liquid is lowered. Therefore, the concentration of the water contained in the chemical solution is preferably 60% by mass or more, and more preferably 70% by mass or more based on the total amount of the solvent.

Further, in order to promote the formation of the protective film by the protective film forming agent, a catalyst may be added to the protective film forming chemical solution. The amount of the catalyst added is preferably from 0.01 to 50% by mass based on 100% by mass of the total amount of the protective film forming agent.

When the protective film forming chemical liquid is raised in temperature, it becomes easy to form the protective film in a shorter period of time. The temperature at which the homogeneous protective film is easily formed is preferably maintained at 10 ° C or higher and does not reach the boiling point of the chemical solution, and is preferably maintained at 15 ° C or higher and lower than the boiling point of the chemical solution by 10 ° C or lower. It is preferable that the temperature of the chemical liquid is maintained at the temperature even when it is held in at least the concave portion of the concave-convex pattern.

The protective film forming chemical liquid used in the protective film forming step can also be used in the subsequent processing of other wafers. For example, in the case of the above-described single-chip method, it is supplied to a certain wafer, and the chemical liquid detached from the wafer is recovered, and can be reused in the subsequent processing of other wafers. Further, in the case of the above-described batch method, a certain batch of chemical liquid treatment is performed in the treatment tank, and after the wafer is taken out, the chemical liquid remaining in the treatment tank can be used for the next batch of treatment. in.

Further, the re-used chemical solution can be used after a part of the chemical liquid is discarded, and a new chemical liquid can be added and used. Further, it is also possible to perform removal of metal impurities by ion exchange resin or distillation, and filtration of particles by a filter. It is used after purification operations such as removal of contaminants.

After the protective film forming step, the chemical liquid held in at least the concave portion of the concave-convex pattern may be replaced with a cleaning liquid different from the chemical liquid (hereinafter, referred to as "cleaning liquid B") ( Hereinafter, it may be referred to as "post-washing step"), and then moved to a drying step. Examples of the cleaning solution B include a water-based cleaning solution, an organic solvent, a mixture of the aqueous cleaning solution and an organic solvent, or at least one of an acid, a base, and a surfactant mixed therein. And the protective film forming agent used for the protective film forming chemical liquid is contained in such a state as to be lower than the concentration of the chemical liquid. The cleaning liquid B is more preferably water, an organic solvent or a mixture of the above water and an organic solvent from the viewpoint of removal of fine particles or metal impurities.

Further, in the post-washing step, the replacement with the above-mentioned cleaning liquid B may be performed twice or more. In other words, the protective liquid for forming a protective film may be replaced with the first cleaning liquid B, and then replaced with a plurality of cleaning liquids B different from the cleaning liquid B of the first type, and then moved to a drying step.

Examples of the organic solvent which is one of preferable examples of the cleaning liquid B include hydrocarbons, esters, ethers, ketones, solvents containing a halogen element, an anthraquinone solvent, a lactone solvent, and carbonic acid. An ester solvent, an alcohol, a derivative of a polyhydric alcohol, a solvent containing a nitrogen element, or the like.

Further, when the protective film formed on the surface of the wafer by the chemical solution of the present invention uses an organic solvent as the cleaning liquid B, the water repellency is hardly lowered by the post-cleaning step, which is preferable.

A mode diagram in which a liquid is held in the recess 4 which is dialyzed by the protective film forming liquid is shown in Fig. 4 . The wafer diagram of the schematic diagram of FIG. 4 represents FIG. One of the a-a' sections. The surface of the concavo-convex pattern is water-repellent by forming the protective film 10 from the above-mentioned chemical liquid. Further, the protective film 10 is also held on the surface of the wafer when the liquid 9 is removed from the concave-convex pattern.

When the protective film 10 is formed on the surface of at least the concave portion of the concave-convex pattern of the wafer by the protective film forming chemical solution, if the contact angle is assumed to be 50 to 130° when water is held on the surface, pattern collapse is less likely to occur. Therefore, it is better. Further, in the case where the pattern collapse is less likely to occur, the contact angle is preferably 65 to 115°.

Furthermore, the post-cleaning step may be omitted as long as possible. When the concentration of the protective film forming agent in the chemical solution for forming a protective film of the present invention is within the above range, the residue of the protective film is not easily left on the surface of the wafer after the film removing step, so that the post-cleaning step can be easily omitted. As a result, the steps are easily simplified.

In the case where the post-cleaning step is omitted, the higher the concentration of water in the protective film forming solution, the larger the contact angle of the protective film forming liquid phase to the surface after the protective film is formed, and thus the effect is easily reduced. The capillary force in the concave portion causes a pattern collapse to be less likely to occur when the chemical liquid is removed. Therefore, the concentration of the water contained in the protective film forming solution with respect to the total amount of the solvent is preferably 80% by mass or more, and more preferably 90% by mass or more.

Next, as described in the drying step described above, the step of removing the liquid held in the concave portion 4 in which the protective film is formed by the chemical liquid from the concave-convex pattern by drying is performed. At this time, the liquid held in the concave portion may be the above-mentioned chemical liquid used in the protective film forming step, and used in the post-washing step. The cleaning solution B may be a mixed liquid of the above. In the above-mentioned mixed liquid, the protective film forming agent contained in the protective film forming chemical liquid is contained so as to be lower than the concentration of the chemical liquid, and the mixed liquid may be replaced by the chemical liquid B in the middle of the cleaning liquid B. The liquid in the state may be a mixed liquid obtained by mixing the above-mentioned protective film forming agent in the cleaning liquid B in advance. From the viewpoint of the cleanliness of the wafer, it is particularly preferably water, an organic solvent, or a mixture of water and an organic solvent. Further, after the liquid is temporarily removed from the surface of the uneven pattern, the cleaning liquid B may be held on the surface of the concave-convex pattern, and then dried.

Further, in the case of performing the cleaning treatment (post-cleaning step) by the surface treatment of the above-mentioned chemical liquid, the time of the step is maintained from the viewpoint of removing particles or impurities on the surface of the concave-convex pattern. The time of the cleaning liquid B is preferably 10 seconds or longer, more preferably 20 seconds or longer. From the viewpoint of maintaining the water-repellent property of the protective film formed on the surface of the uneven pattern, if an organic solvent is used as the cleaning liquid B, the water repellency of the wafer surface can be maintained even after the post-cleaning. Therefore, it is better. On the other hand, if the time of the post-cleaning treatment becomes too long, the productivity is deteriorated, and therefore it is preferably within 15 minutes.

Further, since the contact angle of the water with respect to the surface after the formation of the protective film is large, the capillary force acting on the concave portion is easily reduced, and as a result, pattern collapse is less likely to occur when the chemical liquid is removed. Water may also be used as the above-mentioned cleaning liquid B.

In the above drying step, the liquid holding the concave-convex pattern is removed by drying. The drying is preferably by spin drying, IPA (2-propanol) vapor drying Drying, malangani drying, heat drying, air drying, warm air drying, vacuum drying, etc. are well known drying methods.

Next, the step of removing the protective film is carried out as described in the above-described film removal step. When the water-repellent protective film is removed, it is effective to cut the C-C bond and the C-F bond in the water-repellent protective film. The method is not particularly limited as long as the bond can be cut, and examples thereof include light irradiation on the surface of the wafer, heating of the wafer, exposure of the wafer to ozone, and surface irradiation of the wafer. Plasma irradiation, corona discharge on the surface of the wafer, and the like.

In the case where the protective film is removed by light irradiation, it is preferred that the irradiation includes an energy shorter than a bond energy of 83 kcal/mol or 116 kcal/mol which is equivalent to a CC bond or a CF bond in the protective film. Ultraviolet light at wavelengths of 340 nm and 240 nm. As the light source, a metal halide lamp, a low pressure mercury lamp, a high pressure mercury lamp, an excimer lamp, a carbon arc lamp or the like can be used. The ultraviolet irradiation intensity is a metal halide lamp, for example, an illuminance meter (illumination 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) The measurement value of ]) is preferably 100 mW/cm ² or more, and more preferably 200 mW/cm ² or more. Further, if the irradiation intensity is less than 100 mW/cm ² , it takes a long time to remove the protective film. Further, in the case of a low-pressure mercury lamp, ultraviolet rays having a shorter wavelength are irradiated. Therefore, even if the irradiation intensity is low, the protective film can be removed in a short time, which is preferable.

Further, when the protective film is removed by light irradiation, ozone is generated while decomposing the constituent components of the protective film by ultraviolet rays. When the constituent components of the protective film are oxidized and volatilized by the ozone, the treatment time is shortened, which is particularly preferable. As the light source, a low pressure mercury lamp, an excimer lamp or the like can be used. Further, it is also possible to perform heating by irradiating the wafer while performing light irradiation.

In the case of heating the wafer, it is preferred to heat the wafer at 400 to 1000 ° C, preferably 500 to 900 ° C. The heating time is preferably carried out at a temperature of from 10 seconds to 60 minutes, preferably from 30 seconds to 10 minutes. Further, in this step, ozone exposure, plasma irradiation, corona discharge, or the like may be used in combination. Further, it is also possible to perform light irradiation while heating the wafer.

The method of removing the protective film by heating includes a method of bringing the wafer into contact with a heat source, a method of placing the wafer in a heated environment such as a heat treatment furnace, and the like. Furthermore, the method of placing the wafer in a heated environment facilitates evenly imparting energy for removing the protective film to the surface of the wafer even when processing a plurality of wafers. It is an industrially advantageous method which is easy to handle and can be processed in a short time and has a high processing capacity.

In the case where the wafer is exposed to ozone, it is preferable to supply ozone generated by ultraviolet irradiation such as a low-pressure mercury lamp or low-temperature discharge using a high voltage to the wafer surface. The wafer can be exposed to light while exposed to ozone, and can be heated.

In the film removal step, the protective film on the surface of the wafer can be effectively removed by combining the above-described light irradiation, heating, ozone exposure, plasma irradiation, corona discharge, or the like.

<Second view according to the present invention>

Next, the present invention will be described in detail based on the second aspect.

Before the surface treatment using the above-mentioned protective film forming chemical liquid is carried out, it is usually the case that the pretreatment steps listed below are often carried out.

a pretreatment step 1 of forming a surface of the wafer with a concave-convex pattern; a pretreatment step 2 of washing the surface of the wafer with an aqueous cleaning solution; and replacing the aqueous cleaning solution with a different aqueous cleaning solution The pretreatment step 3 of the cleaning solution A (hereinafter, abbreviated as "washing liquid A").

Furthermore, there are cases where the pre-processing step 2 or the pre-processing step 3 is omitted.

In the above pretreatment step 1, the pattern forming method is first, applying a resist on the surface of the wafer, and thereafter exposing the resist via a resist mask, and exposing the exposed resist or not The exposed resist is etched away to form a resist having a desired concavo-convex pattern. Further, by pressing the patterned mold against the resist, a resist having a concavo-convex pattern can also be obtained. The wafer is then etched. At this time, the surface of the wafer corresponding to the concave portion of the resist pattern is selectively etched. Finally, if the resist is peeled off, a wafer having a concavo-convex pattern can be obtained.

By the pretreatment step described above, a concave-convex pattern is formed on the surface, and at least one element selected from the group consisting of titanium, tungsten, aluminum, copper, tin, antimony, and antimony is contained on the surface of the concave portion of the concavo-convex pattern. Wafer (metal wafer). Examples of the metal-based wafer include a substance containing at least one element selected from the group consisting of titanium, tungsten, aluminum, copper, tin, antimony, and antimony (hereinafter, referred to as "metal-based substance" The layer is coated with a wafer, a wafer containing a plurality of components including germanium and/or germanium dioxide (SiO ₂ ), a silicon carbide wafer, a sapphire wafer, various compound semiconductor wafers, a plastic wafer, or the like. On the surface, a multilayer film is formed on the wafer, at least one of which is a layer of the above-described metal-based substance, and the above-described uneven pattern forming step is performed in a layer including the metal-based substance layer. Further, when the concave-convex pattern is formed, at least one of the surfaces of the concave-convex pattern surface of the concave-convex pattern is the metal-based material.

Examples of the metal-based material include titanium nitride, titanium oxide, and titanium; and tungsten or tungsten oxide; and aluminum; As the material containing copper element, there are copper, copper oxide, etc.; as a substance containing tin element, tin, acidified tin, etc.; as a substance containing a bismuth element, there are ruthenium, ruthenium oxide, ruthenium nitride, etc.; As a substance containing a cerium element, there are cerium, cerium oxide, and the like.

Further, the protective film may be formed on the surface of the metal-based material for a wafer including a plurality of components containing the metal-based substance. The wafer including the plurality of components is also included in at least one of the surface of the concave portion in which the metal-based substance is formed, or at least one of the surface of the concave portion is formed as the metal-based substance when the concave-convex pattern is formed. Further, the protective film formed by the chemical solution of the present invention is a surface of at least the metal-based substance portion of the uneven pattern. Therefore, the protective film may be formed on at least one of the surfaces of the recessed portions of the metal-based wafer.

In addition, since the protective film forming chemical liquid is likely to form an excellent water-repellent protective film on the surface of the article containing the titanium element on the surface, the wafer is preferably formed with a concave-convex pattern on the surface and contained on the concave portion surface of the concave-convex pattern. Wafer of titanium.

Examples of the aqueous cleaning solution used in the pretreatment step 2 include water or at least one of an organic solvent, hydrogen peroxide, ozone, an acid, a base, and a surfactant prepared by mixing in water. The aqueous solution (for example, the water content is 10% by mass or more).

Further, in the pretreatment step 2, the replacement with the aqueous cleaning solution may be carried out twice or more. The aqueous cleaning solution used at this time may be different.

In the pretreatment step 2, after the surface is washed with the aqueous cleaning solution, the water-based cleaning solution is directly removed by drying or the like, or the water-based cleaning solution is replaced with water, and then the water is removed by drying or the like. The width of the concave portion is small, and the longitudinal and lateral directions of the convex portion are relatively large, and the pattern collapse is likely to occur. This concave-convex pattern is defined as described in FIGS. 1 and 2 . Fig. 1 is a view showing an example of a schematic view when a wafer 1 having a surface having a concave-convex pattern 2 is formed by stereoscopic observation, and Fig. 2 is a view showing a portion of the a-a' cross section of Fig. 1. The width 5 of the concave portion is represented by the interval between the convex portion 3 and the convex portion 3 as shown in Fig. 2, 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. The pattern collapse in the washing step is likely to occur when the width of the concave portion is 70 nm or less, particularly 45 nm or less, and the aspect ratio is 4 or more, particularly 6 or more.

In the present invention, the cleaning method of the wafer is not particularly limited as long as the chemical liquid cleaning liquid can be held in at least the concave portion of the concave-convex pattern of the wafer. As a method of cleaning the wafer, a wafer in which the wafer is held at a substantially horizontal level and rotated to supply a liquid toward the vicinity of the center of rotation, and the wafer is washed one by one by washing, or a single sheet method may be used. A plurality of wafers are immersed in a washing tank to wash the batch. Furthermore, as a concave-convex pattern to the wafer The form of the chemical solution or the cleaning solution when the chemical solution or the cleaning solution is supplied to the concave portion is not particularly limited as long as it is liquid when held in the concave portion, and is, for example, a liquid or a vapor.

The cleaning solution A used in the pretreatment step 3 means an organic solvent, a mixture of the organic solvent and the aqueous cleaning solution, and at least one of an acid, a base, and a surfactant mixed with the cleaning liquid. . Furthermore, it is preferable to replace the cleaning liquid A with the protective film forming chemical liquid, and to hold the protective film forming chemical liquid in at least the concave portion of the concave-convex pattern (water-repellent protective film forming step).

Examples of the organic solvent which is one of preferable examples of the cleaning liquid A include hydrocarbons, esters, ethers, ketones, solvents containing halogen elements, anthraquinone solvents, alcohols, and polyols. A derivative, a solvent containing a nitrogen element, or the like.

Further, from the viewpoint of cleanliness, the cleaning liquid A is preferably an organic solvent, a mixture of water and an organic solvent. In addition, when the organic solvent contains a water-soluble organic solvent (having a solubility of 5 parts by mass or more based on 100 parts by mass of water), it is preferably replaced with an aqueous cleaning solution.

Further, in the pretreatment step 3, the replacement with the cleaning liquid A can be carried out twice or more. In other words, the aqueous cleaning solution used in the pretreatment step 2 may be replaced with the first cleaning liquid A, and then replaced with a plurality of cleaning liquids A different from the cleaning liquid A, and then replaced with the above-mentioned cleaning liquid A. A protective film forming drug solution.

In the case where the aqueous cleaning solution used in the pretreatment step 2 can be directly replaced with the protective liquid for forming the protective film, the replacement by the cleaning liquid A may be omitted (pretreatment step 3).

Moreover, the cleaning method of the wafer of the present invention is preferably performed before the water-repellent protective film forming step, that is, as the pre-treatment step 2 and/or the pre-treatment step 3, including using a cleaning liquid containing water and/or alcohol. The step of washing the surface of the wafer described above.

FIG. 3 is a schematic view showing a state in which the protective film forming chemical liquid 8 is held in the concave portion 4 in the protective film forming step. The wafer of the schematic diagram of Fig. 3 represents one of the a-a' sections of Fig. 1. At this time, the surface is dialed by the formation of a protective film on the surface of the concave portion 4.

The water-repellent protective film forming agent contained in the aqueous solution for forming a water-repellent protective film to be used in the method for cleaning a wafer of the present invention is preferably selected from the compounds represented by the above general formulas [1] to [6] and At least one of its salt compounds.

The hydrocarbon group contained in R ² of the above formula [1] may, for example, be an alkyl group, an alkylene group or a hydrogen atom which is partially or wholly replaced by a fluorine element.

Further, R ^{2 is} preferably -OR ¹¹ (R ¹¹ is a hydrocarbon group having 1 to 18 carbon atoms). Further, when the carbon number of R ¹¹ is from 1 to 8, particularly from 1 to 4, more excellent water repellency can be imparted, which is preferable. Further, R ^{11 is} preferably a linear alkyl group.

Further, in order to impart more excellent water repellency, the water repellency protective film forming agent is preferably selected from the above formula [7] and the above formula [3] in which a is 2 of the above formula [1]. b is at least one of the compound represented by the above formula [8] and a salt compound thereof.

Moreover, it is preferable that the water-repellent protective film forming agent is at least one selected from the compounds represented by the following general formulas [7] and [8].

Further, the water-repellent protective film forming agent is particularly preferably a compound represented by the above formula [7].

Examples of R ¹ , R ³ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ^{10 in the} above formulas [1] to [8] include, for example, an alkyl group, a phenyl group or a phenyl group. The base substituent, the naphthyl group, and some or all of the hydrogen elements of the hydrocarbon groups are substituted by a fluorine element or the like.

Further, the carbon numbers of R ¹ , R ³ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ^{10 in} the above general formulae [1] to [8] are 2 to 16, especially 4 to 14 Furthermore, it is 6 to 14, and it is preferable to provide more excellent water repellency. Further, the hydrocarbon group in which a part or all of the hydrogen element described above may be substituted with a fluorine element is preferably an alkyl group, and more preferably a linear alkyl group. When the hydrocarbon group is a linear alkyl group, when the protective film is formed, the hydrophobic portion of the protective film forming agent is easily aligned in the vertical direction with respect to the surface of the protective film, so that the water repellency imparting effect can be further improved. Better. Further, in order to impart more excellent water repellency, R ¹ , R ³ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ^{10 of the} above formulas [1] to [8] are preferably A hydrocarbon group in which part or all of the hydrogen element is replaced by a fluorine element.

The protective film forming agent may be a salt compound of the compound represented by the above formulas [1], [2], [4], [5], and [7], for example, an ammonium salt or an amine salt. Further, the protective film forming agent may be a salt compound of a compound represented by the above formulas [3], [6] and [8], for example, a salt such as a carbonate, a hydrochloride, a sulfate or a phosphate.

In addition, the concentration of the protective film forming agent in the protective film forming chemical solution is preferably 0.0005 to 2% by mass based on 100% by mass of the total amount of the chemical liquid. When it is less than 0.0005 mass%, the water-repellent imparting effect tends to be insufficient, and if it exceeds 2 mass%, there is a tendency that it is hard to be dissolved in the solvent used in the above-mentioned chemical liquid. Further, it is preferably 0.001 to 1% by mass, particularly preferably 0.0015 to 0.8% by mass.

As a solvent used for the chemical solution for forming a protective film, water, an organic solvent, and a mixed liquid of water and an organic solvent can be preferably used. As the organic solvent, for example, a hydrocarbon, an ester, an ether, a ketone, a solvent containing a halogen element, an anthraquinone solvent, a lactone solvent, a carbonate solvent, an alcohol, or a derivative of a polyol can be preferably used. a substance, a solvent containing nitrogen, or a mixture thereof.

Specific examples of the organic solvent include the same as those enumerated in the first aspect of the present invention.

In addition, when non-combustible is used in part or all of the solvent, the protective film forming chemical liquid is incombustible, or the burning point is high, and the risk of the chemical liquid is lowered, which is preferable. The solvent containing a halogen element is mostly nonflammable, and the solvent containing a nonflammable halogen element is preferably used as a nonflammable organic solvent. Further, water can also be preferably used as a nonflammable solvent.

Further, since the derivative of the polyhydric alcohol is often a higher ignition point, the risk of the protective film forming chemical solution can be lowered, which is preferable.

Moreover, in consideration of the protective film forming ability of the protective film forming chemical solution, the solvent is preferably a hydrocarbon, an ester, an ether, a ketone, a derivative of a polyol having no hydroxyl group, water, or the like. Mixture. Further, in consideration of the substitution property with the aqueous cleaning solution, a derivative of a polyol having no hydroxyl group, water, or a mixed liquid thereof is preferable. Further, the protective film forming agent of the alcohol or the polyol derivative having a hydroxyl group is excellent in solubility. Therefore, when the solvent is used as the solvent contained in the chemical solution, the protective film forming agent can be dissolved at a high concentration, and a chemical solution having a high protective film formation property can be easily obtained. Therefore, the solvent can be used as the above. The solvent contained in the liquid.

Further, in order to promote the formation of the protective film by the protective film forming agent, a catalyst may be added to the protective film forming chemical solution. The amount of the catalyst added is preferably from 0.01 to 50% by mass based on 100% by mass of the total amount of the protective film forming agent.

When the protective film forming chemical liquid is raised in temperature, it becomes easy to form the protective film in a shorter period of time. The temperature at which the homogeneous protective film is easily formed is preferably maintained at 10 ° C or higher and does not reach the boiling point of the chemical solution, and is preferably maintained at 15 ° C or higher and lower than the boiling point of the chemical solution by 10 ° C or lower. It is preferable that the temperature of the chemical liquid is maintained at the temperature even when it is held in at least the concave portion of the concave-convex pattern.

The protective film forming chemical liquid used in the protective film forming step can also be used in the subsequent processing of other wafers. For example, in the case of the above-described single-chip method, it is supplied to a certain wafer, and the chemical liquid detached from the wafer is recovered, and can be reused in the subsequent processing of other wafers. Further, in the case of the above-described batch method, a certain batch of chemical liquid treatment is performed in the treatment tank, and after the wafer is taken out, the chemical liquid remaining in the treatment tank can be used for the next batch of treatment. in.

Further, the re-used chemical solution can be used after a part of the chemical liquid is discarded, and a new chemical liquid can be added and used. Further, it is also used after a purification operation such as removal of water molecules such as molecular sieves or removal of water molecules such as distillation, removal of metal impurities by ion exchange resin or distillation, removal of contaminants such as fine particles filtered by a filter, and the like.

After the protective film forming step, the liquid system remaining in the concave portion of the wafer is removed by drying (hereinafter, the drying operation is sometimes referred to as "dry" Drying step").

Further, after the protective film forming step, the chemical liquid held in at least the concave portion of the concave-convex pattern may be replaced with a cleaning liquid different from the chemical liquid (hereinafter, it may be referred to as "cleaning liquid B"). (The following may be referred to as "post-washing step"), and then moved to the drying step. Examples of the cleaning solution B include a water-based cleaning solution, an organic solvent, a mixture of the aqueous cleaning solution and an organic solvent, or at least one of an acid, a base, and a surfactant mixed therein. And the protective film forming agent used for the protective film forming chemical liquid is contained in such a state as to be lower than the concentration of the chemical liquid. The cleaning liquid B is more preferably water, an organic solvent or a mixture of the above water and an organic solvent from the viewpoint of removal of fine particles or metal impurities.

Further, in the post-washing step, the replacement with the above-mentioned cleaning liquid B may be performed twice or more. In other words, the protective liquid for forming a protective film may be replaced with the first cleaning liquid B, and then replaced with a plurality of cleaning liquids B different from the cleaning liquid B of the first type, and then moved to a drying step.

Examples of the organic solvent which is one of preferable examples of the cleaning liquid B include hydrocarbons, esters, ethers, ketones, solvents containing a halogen element, an anthraquinone solvent, a lactone solvent, and carbonic acid. An ester solvent, an alcohol, a derivative of a polyhydric alcohol, a solvent containing a nitrogen element, or the like.

Further, when the protective film formed on the surface of the wafer by the chemical solution of the present invention uses an organic solvent as the cleaning liquid B, the water repellency is hardly lowered by the post-cleaning step, which is particularly preferable.

A mode diagram in which a liquid is held in the recess 4 which is dialyzed by the protective film forming liquid is shown in Fig. 4 . The wafer diagram of the schematic diagram of FIG. 4 represents FIG. One of the a-a' sections. The surface of the concavo-convex pattern is water-repellent by forming the protective film 10 from the above-mentioned chemical liquid. Further, the protective film 10 is also held on the surface of the wafer when the liquid 9 is removed from the concave-convex pattern.

When the protective film 10 is formed on the surface of at least the concave portion of the concave-convex pattern of the wafer by the protective film forming chemical solution, if the contact angle is assumed to be 50 to 130° when water is held on the surface, pattern collapse is less likely to occur. Therefore, it is better. Further, in the case where the pattern collapse is less likely to occur, the contact angle is preferably 65 to 115°.

Next, as described in the drying step described above, the step of removing the liquid held in the concave portion 4 in which the protective film is formed by the chemical liquid from the concave-convex pattern by drying is performed. At this time, the liquid held in the concave portion may be the above-mentioned chemical liquid used in the protective film forming step, the above-mentioned cleaning liquid B used in the post-cleaning step, or a mixed liquid of these. In the above-mentioned mixed liquid, the protective film forming agent contained in the protective film forming chemical liquid is contained so as to be lower than the concentration of the chemical liquid, and the mixed liquid may be replaced by the chemical liquid B in the middle of the cleaning liquid B. The liquid in the state may be a mixed liquid obtained by mixing the above-mentioned protective film forming agent in the cleaning liquid B in advance. From the viewpoint of the cleanliness of the wafer, it is particularly preferably water, an organic solvent, or a mixture of water and an organic solvent. Further, after the liquid is temporarily removed from the surface of the uneven pattern, the cleaning liquid B may be held on the surface of the concave-convex pattern, and then dried.

Further, in the case of performing the cleaning treatment (post-cleaning step) by the surface treatment of the above-mentioned chemical liquid, the time of the step is maintained from the viewpoint of removing particles or impurities on the surface of the concave-convex pattern. Cleaning solution B The time is preferably 5 seconds or longer, preferably 10 seconds or longer, more preferably 20 seconds or longer. From the viewpoint of maintaining the water-repellent property of the protective film formed on the surface of the uneven pattern, if an organic solvent is used as the cleaning liquid B, the water repellency of the wafer surface can be maintained even after the post-cleaning. Therefore, it is better. On the other hand, if the time of the post-cleaning treatment becomes too long, the productivity is deteriorated, and therefore it is preferably within 15 minutes.

Further, since the contact angle of the water with respect to the surface after the formation of the protective film is large, the capillary force acting on the concave portion is easily reduced, and as a result, pattern collapse is less likely to occur when the chemical liquid is removed. Water may also be used as the above-mentioned cleaning liquid B.

In the above drying step, the liquid held in the concave-convex pattern is removed by drying. The drying is preferably carried out by a known drying method such as spin drying, IPA (2-propanol) vapor drying, mazonic drying, heat drying, air drying, warm air drying, vacuum drying, or the like.

After the drying step, the protective film formed on the surface of the wafer is removed (hereinafter, the removal operation is referred to as "film removal step"). When the water-repellent protective film is removed, it is effective to cut the C-C bond and the C-F bond in the water-repellent protective film. The method is not particularly limited as long as the bond can be cut. For example, light irradiation on the surface of the wafer, heating of the wafer, exposure of the wafer to ozone, and electricity on the surface of the wafer are exemplified. Plasma irradiation, corona discharge on the surface of the wafer, and the like.

In the case where the protective film is removed by light irradiation, it is preferred that the irradiation includes an energy shorter than a bond energy of 83 kcal/mol or 116 kcal/mol which is equivalent to a CC bond or a CF bond in the protective film. Ultraviolet light at wavelengths of 340 nm and 240 nm. As the light source, a metal halide lamp, a low pressure mercury lamp, a high pressure mercury lamp, an excimer lamp, a carbon arc lamp or the like can be used. The ultraviolet irradiation intensity is a metal halide lamp, for example, an illuminance meter (illumination 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) The measurement value of ]) is preferably 100 mW/cm ² or more, and more preferably 200 mW/cm ² or more. Further, if the irradiation intensity is less than 100 mW/cm ² , it takes a long time to remove the protective film. Further, in the case of a low-pressure mercury lamp, ultraviolet rays having a shorter wavelength are irradiated. Therefore, even if the irradiation intensity is low, the protective film can be removed in a short time, which is preferable.

In the case where the protective film is removed by light irradiation, ozone is generated by decomposing the constituent components of the protective film by ultraviolet rays, and the constituent components of the protective film are oxidized and volatilized by the ozone. It is shorter, so it is especially good. As the light source, a low pressure mercury lamp, an excimer lamp or the like can be used. Further, it is also possible to perform heating by irradiating the wafer while performing light irradiation.

In the case of heating the wafer, it is preferred to heat the wafer at 400 to 1000 ° C, preferably 500 to 900 ° C. The heating time is preferably carried out at a temperature of from 10 seconds to 60 minutes, preferably from 30 seconds to 10 minutes. Further, in this step, ozone exposure, plasma irradiation, corona discharge, or the like may be used in combination. Further, it is also possible to perform light irradiation while heating the wafer.

The method of removing the protective film by heating includes a method of bringing the wafer into contact with a heat source, a method of placing the wafer in a heated environment such as a heat treatment furnace, and the like. Furthermore, the method of placing the wafer in a heated environment is even In the case where a plurality of wafers are processed, it is easy to uniformly apply energy for removing the protective film to the surface of the wafer, and in this respect, it is industrially simple in that the processing is simple and the processing can be completed in a short time. Favorable method.

In the case where the wafer is exposed to ozone, it is preferable to supply ozone generated by ultraviolet irradiation such as a low-pressure mercury lamp or low-temperature discharge using a high voltage to the wafer surface. The wafer can be exposed to light while exposed to ozone, and can be heated.

In the film removal step, the protective film on the surface of the wafer can be effectively removed by combining the above-described light irradiation, heating, ozone exposure, plasma irradiation, and corona discharge.

Example

A cleaning liquid in which the surface of the wafer is formed into a surface having a concavo-convex pattern and replaced with at least a concave portion of the concave-convex pattern by another cleaning liquid has been studied in other literatures and the like, and is an established technique. In the invention, the evaluation of the chemical solution for forming a protective film is performed. Further, as shown by the following formula P = 2 × γ × cos θ / S (where γ is the surface tension of the liquid held in the concave portion, and θ is the contact angle of the surface of the concave portion with the liquid held in the concave portion, S is the width of the recess)

As is clear, the pattern collapse depends mostly on the contact angle of the cleaning liquid with 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 concave portion 4 of the concave-convex pattern 2, the contact angle of the liquid droplets may be related to the capillary force acting on the concave portion equivalent to the pattern collapse, and thus may also be of the above formula. Comment on the contact angle with the droplets of the protective film 10. The price is derived from the capillary force. Further, in the examples, water as a representative of the aqueous washing liquid is used as the washing liquid. If it is assumed that the contact angle is 50 to 130° when water is held on the surface of the protective film, pattern collapse is less likely to occur, and therefore, if it is 65 to 115°, pattern collapse is less likely to occur. Especially good.

However, in the case of a wafer having a concave-convex pattern on its surface, the contact angle of the protective film 10 itself formed on the surface of the concave-convex pattern cannot be accurately evaluated.

The contact angle of the water droplets is evaluated by adding a few μl of water droplets to the surface of the sample (substrate) as described in JIS R 3257 "Test method for wettability of the surface of the substrate glass", by water droplets and the surface of the substrate. The measurement of the angle formed is carried out. However, in the case of a patterned wafer, the contact angle becomes very large. The reason for this is that since the Wenzel effect or the Cassie effect is generated, the contact angle is affected by the surface shape (roughness) of the substrate, and the apparent contact angle of the water droplets is increased.

Therefore, in the first embodiment of the first aspect of the present invention, the chemical liquid is supplied to a wafer having a smooth surface, and a protective film is formed on the surface of the wafer, and the protective film is formed as a concave-convex pattern formed on the surface. The protective film 10 on the surface of the wafer 1 was subjected to various evaluations. Further, in the first embodiment, the wafer having a smooth surface is used for a wafer having a titanium nitride layer and having a titanium nitride layer on a wafer having a smooth surface (indicated as TiN in the table), And on the wafer with a smooth surface, the wafer with the tantalum layer on the wafer (denoted as Ru).

<Example I>

The details are described below. Hereinafter, the evaluation method of the wafer to which the protective film forming chemical solution is supplied, the preparation of the protective film forming chemical liquid, and the evaluation result after the protective film forming chemical liquid is supplied to the wafer will be described.

[Evaluation method of wafer supplied with protective film forming liquid]

As evaluation methods of the wafer to which the protective film forming chemical liquid is supplied, the following evaluations (1) to (3) are performed.

(1) Evaluation of contact angle of protective film formed on the surface of the wafer

About 2 μl of pure water was dropped on the surface of the wafer on which the protective film was formed, and the angle (contact angle) between the water droplet and the surface of the wafer was measured by a contact angle meter (manufactured by Kyowa Interface Science: CA-X type). Here, the contact angle of the protective film is set to be in the range of 50 to 130°.

(2) Removal of protective film

The sample was irradiated with UV light (UltraViolet, ultraviolet light) of a metal halide lamp for 2 hours under the following conditions, and the removal property of the protective film in the film removal step was evaluated. After the irradiation, the contact angle of the water droplets was set to 30 or less, and it was set as a pass.

. Light: M015-L312 manufactured by EYE GRAPHICS (strength: 1.5 kW)

. Illuminance: The measured value under the following conditions is 128 mW/cm ²

. Measuring device: UV intensity meter (manufactured by Konica Minolta Sensing, UM-10)

. Receiving department: UM-360

(light receiving wavelength: 310~400 nm, peak wavelength: 365 nm)

. Measurement mode: illuminance measurement

(3) Surface smoothness evaluation of the wafer after removal of the protective film

The surface observation was performed by an atomic force electron microscope (manufactured by Seiko Instruments: SPI3700, 2.5 μm square scan), and the difference in the center line average surface roughness of the surface before and after the wafer cleaning: Ra (nm) ΔRa (nm) was determined. In addition, the Ra system applies the center line average roughness defined in JIS B 0601 to the measurement surface and expands it three-dimensionally as the value obtained by averaging the absolute value of the deviation from the reference surface to the designated surface. It is calculated by the following formula.

Here, X _L , X _R , Y _B , and Y _T represent the measurement ranges of the X coordinate and the Y coordinate, respectively. S ₀ is an area when the measurement surface is desirably flat, and is set to a value of (X _R - X _L ) × (Y _{B -} Y _T ). Further, F(X, Y) represents the height at the measurement point (X, Y), and Z ₀ represents the average height in the measurement plane.

The Ra value of the wafer surface before the formation of the protective film and the Ra value of the wafer surface after the removal of the protective film are measured, and if the difference (ΔRa) between the two is within ±1 nm, the wafer surface is not washed. It was clean and corroded, and the residue of the above protective film was not present on the surface of the wafer, and it was made acceptable.

[Example I-1]

(1) Preparation of protective liquid for forming a protective film

Octadecylphosphonic acid [C ₁₈ H ₃₇ P(O)(OH) ₂ ] 0.002 g as a water-repellent protective film forming agent, 90 g of water as a solvent, propylene glycol monomethyl ether acetate (hereinafter, In the case of the "PGMEA", 9.98 g, the mixture is stirred for 18 hours, and the concentration of the protective film forming agent relative to the total amount of the protective film forming liquid (hereinafter referred to as "protective film forming agent concentration") is 20 ppm by mass. The concentration of the water contained in the protective film forming solution with respect to the total amount of the solvent (hereinafter referred to as "water concentration") is 90% by mass of the protective film forming chemical liquid.

(2) Washing of wafers with titanium nitride film

As a pretreatment step 2, a smooth wafer with a titanium nitride film (a silicon nitride layer having a titanium nitride layer having a thickness of 50 nm on the surface) is immersed in 1% by mass of hydrogen peroxide water for 1 minute, followed by pure The mixture was immersed in water for 1 minute, and further, as a pretreatment step 3, immersed in isopropyl alcohol (hereinafter referred to as "iPA") for 1 minute.

(3) Surface treatment using a protective film forming liquid for the surface of a wafer with a titanium nitride film

In the protective film forming step, the wafer with the titanium nitride film is immersed in the protective film forming chemical solution prepared in the above "(1) Preparation of protective film forming solution" at 20 ° C for 10 minutes. A protective film is formed on the surface of the wafer. Thereafter, as a post-cleaning step, the wafer with the titanium nitride film is immersed in iPA for 1 minute, and as a drying step, the wafer with the titanium nitride film is taken out from the iPA, and air is sprayed. The surface of the iPA is removed.

The titanium nitride film-attached wafer obtained by the method described in "Evaluation Method of Wafer Provided with Protective Film Forming Liquid" was evaluated as shown in Table 1, and the initial stage before surface treatment. When the contact angle is less than 10°, the contact angle after the surface treatment is 106°, and the water repellency imparting effect is excellent. Further, the contact angle after UV irradiation was less than 10°, and the protective film was removed. Further, the ΔRa value of the wafer after the UV irradiation was within ±0.5 nm, and the wafer was not corroded during the cleaning, and it was confirmed that the residue of the protective film did not remain after the UV irradiation.

[Examples I-2 to I-53]

The protective film forming agent, the protective film forming agent concentration, the solvent of the protective film forming chemical solution, the temperature of the protective film forming chemical liquid, and the post-cleaning step are appropriately changed, and the surface treatment of the wafer is performed. Further, the evaluation was carried out. The results are shown in Tables 1 and 2. Furthermore, in Examples I-8, I-12, I-13, I-16, I-20, I-21, I-23, I-27, I-28, I-32, I-33, In I-38, I-39, I-43, I-44, I-46, I-47, and I-49 to I-53, the post-washing step was not performed. That is, after the water-repellent protective film forming step, the wafer with the titanium nitride film is taken out from the chemical liquid, and air is sprayed to remove the chemical liquid on the surface.

In the table, "C ₁₂ H ₂₅ P(O)(OH) ₂ ") means dodecylphosphonic acid, and "C ₁₀ H ₂₁ P(O)(OH) ₂ " means decylphosphonic acid. "C ₈ H ₁₇ P(O)(OH) ₂ " represents octylphosphonic acid, and "C ₆ F ₁₃ -C ₂ H ₄ -P(O)(OH) ₂ ") means perfluorohexylethylphosphonic acid "C ₆ H ₁₃ P(O)(OH) ₂ " represents hexylphosphonic acid, and "C ₄ H ₉ P(O)(OH) ₂ ") means butylphosphonic acid, "C ₆ H ₅ P(O (OH) ₂ ′′ represents phenylphosphonic acid. Further, "DGEEA" means diethylene glycol monoethyl ether acetate, and "PGME" means propylene glycol monomethyl ether.

[Examples I-54]

As a pretreatment step 2, a smooth wafer with a ruthenium film (a ruthenium wafer having a thickness of 300 nm on the surface) is immersed in 1% by mass of ammonia water for 1 minute, and then immersed in pure water for 1 minute. Further, as a pretreatment step 3, it was immersed in iPA for 1 minute. The same manner as in Example I-1 was carried out except that the protective film was formed on the surface of the wafer.

The wafer with the ruthenium film on which the protective film was formed was evaluated by the method described in the "Method for Evaluating a Wafer with a Protective Film Forming Liquid", and the results are as shown in Table 2, and the initial period before the surface treatment. When the contact angle was less than 10°, the contact angle after the surface treatment was 72°, and the water repellency imparting effect was exhibited. Further, the contact angle after UV irradiation was less than 10°, and the protective film was removed. Further, the ΔRa value of the wafer after the UV irradiation was within ±0.5 nm, and the wafer was not corroded during the cleaning, and it was confirmed that the residue of the protective film did not remain after the UV irradiation.

[Examples I-55~I-61]

The protective film forming agent, the protective film forming agent concentration, the solvent of the protective film forming chemical solution, and the temperature of the protective film forming chemical liquid used in Example I-54 were appropriately changed, and the surface treatment of the wafer was performed, and the evaluation was further performed. The results are shown in Table 2.

[Comparative Example I-1]

First, as a protective film forming agent, 0.01 g of N,N-dimethylaminotrimethylnonane [(CH ₃ ) ₃ SiN(CH ₃ ) ₂ ] as a decane coupling agent, 50 g of water as a solvent, DGEEA 49.99 g was mixed and stirred for 18 hours to obtain a protective film forming drug solution having a protective film forming agent concentration of 100 ppm by mass and a water concentration of 50% by mass. Then, washing and surface treatment of the wafer with the titanium nitride film were carried out in the same manner as in Example I-1. The evaluation results are shown in Table 2. The contact angle after the surface treatment was 10°, and no water repellency imparting effect was observed.

[Comparative Example I-2]

Using the protective film forming chemical solution of Comparative Example I-1, the wafer with the ruthenium film was washed and surface-treated in the same manner as in Example I-54. The evaluation results are shown in Table 2. The contact angle after the surface treatment was 16°, and no water-repellent imparting effect was observed.

Next, in the second embodiment of the second aspect of the present invention, the chemical liquid is supplied to a wafer having a smooth surface, and a protective film is formed on the surface of the wafer, and the protective film is formed as a concave-convex pattern formed on the surface. The protective film 10 on the surface of the wafer 1 was subjected to various evaluations. Further, in the embodiment II, the wafer having a smooth surface is used for "a wafer having a titanium nitride film" (TiN in the table) having a titanium nitride layer on a wafer having a smooth surface. A wafer with a tungsten layer on the surface of the wafer with a tungsten layer (denoted as W in the table) and a wafer with a germanium layer on the wafer with a smooth surface (marked as Ru in the table).

<Example II>

The details are described below. Hereinafter, the method of evaluating the contact angle of the protective film formed on the surface of the wafer, the preparation of the chemical solution for forming the protective film, and the evaluation result of supplying the chemical solution for forming the protective film to the wafer will be described.

[Evaluation of Contact Angle of Protective Film Formed on Wafer Surface]

Adding about 2 μl of pure water to the surface of the wafer on which the protective film is formed, and utilizing The antennae (concord interface science: CA-X type) measures the angle (contact angle) between the water droplet and the surface of the wafer. Here, the contact angle of the protective film is set to be in the range of 50 to 130°.

[Example II-1]

(i-1) Preparation of protective film forming liquid

Octadecylphosphonic acid [C ₁₈ H ₃₇ P(O)(OH) ₂ ] 0.002 g as a water-repellent protective film forming agent, propylene glycol monomethyl ether acetate as a solvent (hereinafter, referred to as "PGMEA" 99.998 g was mixed and stirred for 18 hours to obtain a protective film forming drug having a concentration of the protective film forming agent relative to the total amount of the protective film forming liquid (hereinafter referred to as "protective film forming agent concentration") of 0.002% by mass. liquid.

(i-2) Washing of wafers with titanium nitride film

As a pretreatment step 2, a smooth wafer with a titanium nitride film (a silicon nitride layer having a titanium nitride layer having a thickness of 50 nm on the surface) is immersed in 1% by mass of hydrogen peroxide water for 1 minute, followed by pure The mixture was immersed in water for 1 minute, and further, as a pretreatment step 3, immersed in isopropyl alcohol (hereinafter referred to as "iPA") for 1 minute.

(i-3) Surface treatment using a protective film forming liquid for the surface of a wafer with a titanium nitride film

In the protective film forming step, the wafer with the titanium nitride film is immersed in the protective film forming solution prepared in the above "(i-1) Preparation of Protective Film Forming Liquid" at 20 ° C for 10 minutes. A protective film is formed on the surface of the wafer. In addition, iPA which is 1% by mass based on the total amount of the protective film forming chemical solution is mixed into the protective film forming chemical liquid. Thereafter, as a post-cleaning step, the wafer with the titanium nitride film is immersed in iPA For 10 seconds, as a drying step, the wafer with the titanium nitride film was taken out from the iPA, and air was sprayed to remove the iPA on the surface.

(i-4) Evaluation of reusability

The immersion in the protective film forming chemical solution after the "(i-3) surface treatment using the protective film forming chemical liquid on the surface of the wafer on which the titanium nitride film is attached" is performed four times in (i-3) The user performs surface treatment operations on different batches of wafers. By this, iPA which is 5% by mass based on the total amount of the protective film forming chemical solution is mixed into the protective film forming chemical liquid.

The wafer with the titanium nitride film obtained by surface treatment in the first batch was evaluated by the method described in "Evaluation of Contact Angle of Protective Film Formed on Wafer Surface", and the results are shown in Table 3. The initial contact angle before the surface treatment was less than 10°, and the contact angle after the surface treatment was 106°, which exhibited an excellent water-repellent imparting effect. Further, the wafer obtained by the surface treatment in the fifth batch also had a contact angle of 106°, which was confirmed to be reusable.

[Examples II-2 to II-50]

The washing liquid of the pretreatment step 2 or 3 used in the example II-1 is appropriately changed (in the table, it is referred to as "the solvent mixed in the chemical solution forming liquid for the protective film", and further, when the solvent is water When the pretreatment step 3 is not performed, the protective film forming step, the protective film forming agent concentration, the protective film forming agent concentration, and the solvent for the protective film forming chemical solution are not subjected to the surface treatment of the wafer. Further, the evaluation was carried out. The results are shown in Tables 3 and 4.

In the table, "C ₁₂ H ₂₅ P(O)(OH) ₂ ") means dodecylphosphonic acid, and "C ₁₀ H ₂₁ P(O)(OH) ₂ " means decylphosphonic acid. "C ₈ H ₁₇ P(O)(OH) ₂ " represents octylphosphonic acid, and "C ₆ F ₁₃ -C ₂ H ₄ -P(O)(OH) ₂ ") means perfluorohexylethylphosphonic acid "C ₆ H ₁₃ P(O)(OH) ₂ " represents hexylphosphonic acid, and "C ₄ H ₉ P(O)(OH) ₂ ") means butylphosphonic acid, "C ₆ H ₅ P(O (OH) ₂ ′′ represents phenylphosphonic acid. Further, "C ₁₄ H ₂₉ NH ₂ " means tetradecylamine, "C ₁₂ H ₂₅ NH ₂ " means dodecylamine, and "C ₆ F ₁₃ -C ₂ H ₄ -NH ₂ " means Flurohexylethylamine, "C ₈ H ₁₇ NH ₂ " means octylamine, "C ₁₂ H ₂₅ SH" means dodecanethiol, and "C ₈ H ₁₇ COOH" means decanoic acid. Further, "DGEEA" means diethylene glycol monoethyl ether, "DGEEA/iPA" means a solvent obtained by mixing DGEEA and iPA at a mass ratio of 95:5, and "DGEEA/water" means quality of DGEEA and water. A solvent which is a mixture of 95:5, "water/PGME" means a solvent obtained by mixing water with propylene glycol monomethyl ether at a mass ratio of 70:30, and "water/iPA" means a mass ratio of water to iPA. 70:30 mixed solvent.

[Example II-51]

(ii-1) Preparation of protective film forming liquid

The octadecylphosphonic acid [C ₁₈ H ₃₇ P(O)(OH) ₂ ] 0.002 g as a water-repellent protective film forming agent was mixed with PGMEA 99.998 g as a solvent, and stirred for 18 hours to obtain a protective film formation. The drug solution for forming a protective film having a concentration of 0.002% by mass.

(ii-2) Washing of wafers with tungsten film

As a pretreatment step 2, the wafer with the tungsten film is smoothed (the surface has The tantalum wafer of a tungsten layer having a thickness of 50 nm was immersed in 1% by mass of ammonia water for 1 minute, and then immersed in pure water for 1 minute, and further, as a pretreatment step 3, immersed in iPA for 1 minute.

(ii-3) Surface treatment using a protective film forming solution for a wafer surface on which a tungsten film is attached

In the protective film forming step, the wafer with the tungsten film was immersed in the protective film forming chemical solution prepared in the above "(ii-1) Preparation of protective film forming solution" at 20 ° C for 10 minutes. In addition, iPA of 1% by mass based on the total amount of the protective film forming chemical solution can be mixed into the protective film forming chemical liquid. Thereafter, as a post-cleaning step, the wafer with the tungsten film was immersed in iPA for 10 seconds. As a drying step, the wafer with the tungsten film was taken out from the iPA, and air was sprayed to remove the iPA on the surface.

(ii-4) Evaluation of reusability

The immersion in the protective film forming chemical solution after the "(ii-3) surface treatment using the protective film forming chemical solution on the surface of the wafer with the tungsten film" is performed four times, and the user in (ii-3) Surface treatment with different batches of wafers. By this, iPA which is 5% by mass based on the total amount of the protective film forming chemical solution is mixed into the protective film forming chemical liquid.

The wafer with the tungsten film obtained by surface treatment in the first batch was evaluated by the method described in "Evaluation of Contact Angle of Protective Film Formed on Wafer Surface", and the results are shown in Table 4. When the initial contact angle before the treatment was less than 10°, the contact angle after the surface treatment was 68°, and the water repellency imparting effect was exhibited. Further, the wafer obtained by the surface treatment in the fifth batch also had a contact angle of 68°, which was confirmed to be reusable.

[Example II-52~II-70]

The solvent of the pretreatment step 2 or 3 used in Example II-51, the protective film forming agent, the protective film forming agent concentration, and the solvent for the protective film forming chemical solution are appropriately changed, and the surface treatment of the wafer is performed. Its evaluation. The results are shown in Table 4.

[Examples II-71]

As a pretreatment step 2, a smooth wafer with a ruthenium film (a ruthenium wafer having a thickness of 300 nm on the surface) is immersed in 1% by mass of ammonia water for 1 minute, and then immersed in pure water for 1 minute. Further, as a pretreatment step 3, it was immersed in iPA for 1 minute. The wafer was subjected to surface treatment in the same manner as in Example II-51 using this wafer.

The wafer with the ruthenium film obtained by surface treatment in the first batch was evaluated by the method described in "Evaluation of Contact Angle of Protective Film Formed on Wafer Surface", and the results are shown in Table 4. When the initial contact angle before the treatment was less than 10°, the contact angle after the surface treatment was 72°, and the water repellency imparting effect was exhibited. Moreover, the wafer obtained by the surface treatment in the fifth batch also had a contact angle of 70°, and it was confirmed that it could be reused.

[Examples II-72~II-96]

By appropriately changing the cleaning liquid, the protective film forming agent, the protective film forming agent concentration, and the solvent for the protective film forming chemical liquid used in the pretreatment step 2 or 3 used in Example II-71, the surface treatment of the wafer is performed, and further, Its evaluation. The results are shown in Tables 4 and 5.

[Comparative Example II-1]

N,N-dimethylaminotrimethylnonane [(CH ₃ ) ₃ SiN(CH ₃ ) ₂ ] 5 g as a protective film forming agent, PGMEA 95 g as a solvent, and mixed, and stirred for about 5 minutes. Further, a chemical solution having a protective film forming agent concentration of 5% by mass was obtained. The chemical solution was used as the chemical solution for forming a protective film, and the same procedure as in Example II-2 was carried out.

The wafer with the titanium nitride film obtained by surface treatment in the first batch was evaluated by the method described in "Evaluation of Contact Angle of Protective Film Formed on Wafer Surface", and the results are shown in Table 5. When the initial contact angle before the surface treatment was less than 10°, the contact angle after the surface treatment was 18°, and the water repellency imparting effect was insufficient. Further, the wafer contact angle obtained by the surface treatment in the fifth batch was less than 10°, which was equivalent to the initial stage, and no water-repellent imparting effect was observed, and thus it was confirmed that it could not be reused.

1‧‧‧ wafer

2‧‧‧ concave and convex pattern on the surface of the wafer

3‧‧‧The convex part of the pattern

4‧‧‧The recess of the pattern

5‧‧‧Width of the recess

6‧‧‧ Height of the convex part

7‧‧‧Width of the convex part

8‧‧‧ Protective liquid for forming a protective film held in the recess 4

9‧‧‧Liquid held in the recess 4

10‧‧‧Protective film

FIG. 1 is a view showing an example of a schematic view when the wafer 1 having the surface of the uneven pattern 2 is formed by stereoscopic observation.

Figure 2 is a schematic view showing a portion of the a-a' section of Figure 1.

Fig. 3 is a schematic view showing a state in which the protective film forming chemical liquid 8 is held in the concave portion 4 in the washing step.

Fig. 4 is a schematic view showing a state in which a liquid is held in the concave portion 4 in which the protective film is formed.

1‧‧‧ wafer

3‧‧‧The convex part of the pattern

4‧‧‧The recess of the pattern

9‧‧‧Liquid held in the recess 4

10‧‧‧Protective film

Claims (11)

A water-repellent protective film forming chemical liquid, which is characterized in that a concave-convex pattern is formed on a surface thereof, and a concave portion surface of the concave-convex pattern is selected from the group consisting of titanium, tungsten, aluminum, copper, tin, antimony, and bismuth. a surface of at least one of the recesses of at least one of the plurality of elements forming a water-repellent protective film; the chemical liquid containing a water-repellent protective film forming agent and water; and the water-repellent protective film forming agent is selected from the group consisting of At least one of the compound represented by the formula [1] and a salt compound thereof; the concentration of the water contained in the chemical solution relative to the total amount of the solvent is 50% by mass or more; (In the formula [1], R ¹ is a monovalent hydrocarbon group in which a part or all of hydrogen elements may be substituted by a fluorine element and has a carbon number of 1 to 18, and R ^{2 is} independently of each other to contain a part or all of hydrogen elements via a fluorine element. The substituted monovalent organic group having a carbon number of 1 to 18, a is an integer of 0 to 2. The aqueous solution for forming a water-repellent protective film according to claim 1, wherein the water-repellent protective film forming agent is at least one selected from the group consisting of a compound represented by the following formula [2] and a salt compound thereof: (In the formula [2], R ³ is a monovalent hydrocarbon group in which a part or all of the hydrogen element may be substituted with a fluorine element and has a carbon number of 1 to 18). A method for cleaning a wafer, characterized in that the wafer is formed with a concave-convex pattern on a surface thereof, and the surface of the concave portion of the concave-convex pattern is selected from the group consisting of titanium, tungsten, aluminum, copper, tin, antimony, and antimony. In at least one element of the group, the method includes at least a step of forming a water-repellent protective film for holding a protective film forming liquid in at least a concave portion of the concave-convex pattern, a drying step of removing the liquid from the concave-convex pattern by drying, and a film removing step of removing a protective film, wherein the protective film forming chemical liquid contains a water repellent protective film forming agent and water; and the water repellent protective film forming agent is a compound selected from the following general formula [1] and a salt thereof At least one of the compounds; the concentration of the water contained in the chemical solution relative to the total amount of the solvent is 50% by mass or more; (In the formula [1], R ¹ is a monovalent hydrocarbon group in which a part or all of hydrogen elements may be substituted by a fluorine element and has a carbon number of 1 to 18, and R ^{2 is} independently of each other to contain a part or all of hydrogen elements via a fluorine element. The substituted monovalent organic group having a carbon number of 1 to 18, a is an integer of 0 to 2. The method for cleaning a wafer according to claim 3, wherein before the water-repellent protective film forming step, the water system is included in at least the concave portion of the concave-convex pattern The washing process of the water of the washing liquid. The method for cleaning a wafer according to claim 3 or 4, wherein the water-repellent protective film forming agent is at least one selected from the group consisting of a compound represented by the following formula [2] and a salt compound thereof: (In the formula [2], R ³ is a monovalent hydrocarbon group in which a part or all of the hydrogen element may be substituted with a fluorine element and has a carbon number of 1 to 18). The method of cleaning a wafer according to claim 3 or 4, wherein the wafer is a wafer containing at least one of titanium and tantalum on at least a concave surface of the concave-convex pattern. A method for cleaning a wafer, characterized in that the wafer is formed with a concave-convex pattern on a surface thereof, and the surface of the concave portion of the concave-convex pattern is selected from the group consisting of titanium, tungsten, aluminum, copper, tin, antimony, and antimony. At least one element of the group; the method comprising at least a water-repellent protective film forming step of forming a water-repellent protective film containing a water-repellent protective film forming agent for forming a water-repellent protective film on the surface of the wafer The chemical liquid is supplied to at least the concave portion of the wafer, and a water-repellent protective film is formed on the surface of the concave portion; the remaining water-repellent protective film forming chemical liquid generated in the water-repellent protective film forming step, and/or the water repellency Recycling and recycling of the water-repellent protective film forming liquid after the protective film forming step, and the above dialing The aqueous protective film forming agent is a compound having no hydrolyzable functional group. The method of cleaning a wafer according to claim 7, wherein before the step of forming the water-repellent protective film, the step of washing the surface of the wafer with a washing liquid containing water and/or alcohol is used. The method for cleaning a wafer according to claim 7 or 8, wherein the water-repellent protective film forming agent is at least one selected from the group consisting of a compound represented by the following general formulas [1] to [6] and a salt compound thereof: (In the formula [1], R ¹ is a monovalent hydrocarbon group in which a part or all of hydrogen elements may be substituted by a fluorine element and has a carbon number of 1 to 18, and R ^{2 is} independently of each other to contain a part or all of hydrogen elements via a fluorine element. a monovalent organic group substituted with a hydrocarbon group of 1 to 18, a being an integer of 0 to 2); (In the formula [2], R ³ is a monovalent hydrocarbon group in which a part or all of hydrogen elements may be substituted by a fluorine element and has a carbon number of 1 to 18, R ⁴ is a hydrogen group, or a part or all of hydrogen elements may pass through a fluorine element a substituted monovalent hydrocarbon group having a carbon number of 1 to 8); [Chemical Formula 18] (R ⁵ ) _b -NH _3-b [3] (In the formula [3], R ⁵ is a part or all of hydrogen element may be fluorine-containing The element has a carbon number of 1 to 18, and b is an integer of 1 to 3; [Chem. 19] R ⁶ (X) _c [4] (in the formula [4], X is independently a thiol group, Or an aldehyde group, c is an integer of 1 to 6, and R ⁶ is a monovalent hydrocarbon group having a carbon number of 1 to 18 which may be substituted by a fluorine element, and is a hydrogen element or a fluorine element via the X group. Replacer) (In the formula [5], R ⁷ is a monovalent hydrocarbon group in which a part or all of the hydrogen element may be substituted by a fluorine element and has a carbon number of 1 to 18); (In the formula [6], R ⁸ is a monovalent hydrocarbon group having a carbon number of 1 to 18 in which a part or all of the hydrogen element may be substituted by a fluorine element). The method for cleaning a wafer according to claim 7 or 8, wherein the water-repellent protective film forming agent is at least one selected from the group consisting of a compound represented by the following general formulas [7] and [8] and a salt compound thereof: 22] (In the formula [7], R ⁹ is a monovalent hydrocarbon group in which a part or all of the hydrogen element may be substituted by a fluorine element and has a carbon number of 1 to 18); [Chem. 23] R ¹⁰ -NH ₂ [8] (Formula [8] In the formula, R ¹⁰ is a monovalent hydrocarbon group having a carbon number of 1 to 18 in which a part or all of the hydrogen element may be substituted by a fluorine element. The method of cleaning a wafer according to claim 7 or 8, wherein the wafer is a wafer containing at least one of titanium, tantalum and tungsten on at least a concave surface of the concave-convex pattern.