JP2013042094A - Wafer cleaning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer cleaning method capable of reducing pattern collapse by reducing influence of capillary force acting on an uneven pattern in cleaning of a surface of a wafer having the uneven pattern.SOLUTION: The wafer cleaning method comprises: a cleaning step of cleaning a surface of a wafer on which an uneven pattern is formed on the surface with a cleaning liquid; a melt filling step of replacing the cleaning liquid remaining in a recess of the wafer after the cleaning step with a melt for filling in which a treatment agent for filling containing a sublimable material was melt by heating; a cooling deposition step of depositing a solid sublimable material by cooling the melt filled in the recess; and a sublimation and removal step of removing the solid sublimable material deposited on the recess by sublimation. The melt for filling is a melt in which the treatment agent for filling was melt in a temperature range in which the temperature is higher than or equal to a melting point of the contained sublimable material and less than or equal to "melting point plus 25°C".

Description

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

  In the manufacture of semiconductor chips, a fine uneven pattern is formed on the wafer surface through film formation, lithography, etching, etc., and then water (pure water) or an organic solvent is used to clean the wafer surface. Cleaning is done. The elements are in the direction of miniaturization, and the interval between the concave and convex patterns is becoming narrower. For this reason, when washing with water (pure water) and removing the water remaining in the concave portion of the concave / convex pattern by drying from the wafer surface, the capillary phenomenon caused by the pressure difference between the water remaining in the concave portion and the external air Due to the bending force acting on the surface, the problem that the concavo-convex pattern falls tends to occur. This problem has become more prominent in semiconductor chips having a line width (recess width) of 20 nm or 10 nm generation, particularly in the case of a pattern with a concave and convex pattern, for example, a line-and-space pattern. . Further, along with diversification of wafer pattern shapes, some convex portions have fragile locations, and the problem that pattern collapse occurs due to the capillary force acting also in those locations has become prominent. Yes.

  In Patent Document 1, after cleaning and rinsing the substrate surface on which the circuit pattern is formed, the rinsing liquid remaining in the concave portions of the concavo-convex pattern is replaced with a filler, the filler is solidified, and the solidified filler is removed. A substrate processing system is disclosed.

  Patent Document 2 discloses a technique for preventing sticking by pouring a sublimable material dissolved in a solvent into an uneven portion or a movable portion of a semiconductor device, and then evaporating the solvent to precipitate the sublimable material. Yes. This sublimable material is subsequently sublimed and removed.

  In Patent Documents 3 and 4, after cleaning the micro gap between the thin film and the substrate, the sublimable substance in a molten state is attached to the micro gap before the cleaning solution is dried, and the sublimable substance is solidified. A method for preventing the thin film and the substrate or the thin film and the thin film from being in close contact with each other by the surface tension of the cleaning liquid in the minute gap when the cleaning liquid remaining in the concave portions of the uneven pattern is dried by sublimating the sublimable substance later is disclosed. ing.

  Further, a method using supercritical carbon dioxide (Patent Document 5) and a method using freeze drying (Patent Documents 6 and 7) are also disclosed, but all of them require special equipment and conditions. There is a problem that the operation is complicated and the cost increases as a result.

JP 2011-124313 A JP 2008-010638 A JP-A-9-190996 JP-A-9-260337 JP 2008-130585 A JP 11-294948 A US Pat. No. 5,013,693

  Pattern collapse is caused by capillary force acting on the pattern when the wafer is dried. Further, along with the diversification of wafer pattern shapes, some of the convex portions have fragile locations, and the capillary force may act on the locations to cause pattern collapse.

  For this reason, instead of removing the liquid remaining in the concave portion of the pattern directly by drying, the liquid can be expected to be eliminated by replacing it with a solid that can be removed in a subsequent process and removing the solid. Patent Document 1 describes a technique for filling a recess between circuit patterns to prevent the pattern from collapsing. However, polymers and photoresists disclosed as a filler are themselves expensive. In order to solidify after filling, it is necessary to carry out the reaction under special conditions, and the apparatus and processing method therefor become complicated, resulting in a problem of high cost. Also, in the method of removing the solidified filler by plasma treatment or development treatment, there is a risk that the wafer surface may be damaged by the removal, and the removal apparatus and treatment method become complicated, resulting in high cost. There is a problem.

  Patent Documents 2 to 4 describe a method for depositing a sublimable material, but it is not assumed to reduce pattern collapse due to the action of capillary force on the disclosed structures and minute gaps. Therefore, there was room for improvement in order to apply for this purpose.

  It is an object of the present invention to provide a wafer cleaning method that reduces the influence of capillary force acting on the concavo-convex pattern and reduces pattern collapse in cleaning the surface of a wafer having a concavo-convex pattern on the surface.

The present invention
A cleaning step of cleaning the surface of the wafer having a concavo-convex pattern on the surface with a cleaning liquid;
A melt filling process, in which the cleaning liquid remaining in the recesses of the wafer after the cleaning process is replaced with a filling melt obtained by melting a filling processing agent containing a sublimation substance by heating, and filling.
A cooling precipitation step of precipitating a solid sublimable material by cooling the melt filled in the recess,
A method for cleaning a wafer having a sublimation removal step, wherein a solid sublimable substance deposited in the recess is removed by sublimation, wherein the filling melt has a melting point of not less than the melting point of the sublimable substance contained and a melting point of + 25 ° C. or less. A wafer cleaning method characterized by being a melt obtained by melting a processing agent for filling within a temperature range.

  When the filling melt is a melt obtained by melting the filling treatment agent within a temperature range of not less than the melting point of the sublimable substance contained and not less than the melting point + 25 ° C., the sublimable substance can be evaporated in the melt. The accompanying bubble generation is reduced. Therefore, in the melt filling step, when the melt is caused to flow into the recess of the wafer, bubbles are hardly generated in the recess, and as a result, the filling can be performed while suppressing the action of the capillary force. Since the sublimable substance does not melt at a temperature lower than the melting point, that is, does not become a melt, the cleaning liquid cannot be replaced. A temperature exceeding the melting point + 25 ° C. results in a melt containing the sublimable substance, but the sublimable substance evaporates too quickly, so even if the cleaning liquid remaining in the recesses of the wafer can be replaced with the melt, When the sublimable substance evaporates from the liquid, the concave portion cannot be sufficiently filled. In addition, since more bubbles are generated in the melt, bubbles are likely to be generated in the recesses, and capillary forces act on the recesses due to the bubbles, leading to collapse of the pattern. When the melt is a melt obtained by melting the filling treatment agent within the temperature range of the melting point of the sublimable substance to be contained and the melting point + 15 ° C. or less, the temperature of the melt can be cooled more quickly during the cooling precipitation process. Therefore, the amount of evaporation and reduction of the sublimable substance during the cooling precipitation process can be reduced, and as a result, the recesses on the entire surface of the wafer can be more easily filled.

  The filling treatment agent may contain 60% by mass or more of a sublimable substance and 40% by mass or less of an organic solvent. When the sublimable substance is less than 60% by mass and the organic solvent is more than 40% by mass, the solid deposited in the cooling deposition process becomes porous or the deposited solid tends to decrease, and the sublimated substance is sufficient for the recess of the wafer. It is not preferable because it may be difficult to fill the wafer, and a capillary force may act on the concave portion of the wafer by the organic solvent contained. From the viewpoint of sufficiently filling the concave portion of the wafer with the sublimable substance and reducing the capillary force that may act on the concave portion of the wafer by the organic solvent contained, the filling treatment agent contains 95 mass of the sublimable substance. More preferably, the organic solvent is contained in an amount of 5% by mass or less.

  In addition, the filling treatment agent may be made of a sublimable substance from the viewpoint of sufficiently filling the concave portion of the wafer with the sublimable substance and preventing the capillary force from acting on the concave portion of the wafer.

  The organic solvent is preferably an organic solvent having a boiling point higher than the temperature of the filling melt.

  Moreover, it is preferable that the cleaning liquid remaining in the concave portion of the wafer after the cleaning process is an organic solvent having a boiling point higher than the temperature of the filling melt.

  Moreover, it is preferable that the cleaning liquid remaining in the concave portion of the wafer after the cleaning process is soluble in the filling melt.

  Further, in the melt filling step, the cleaning liquid remaining in the recesses is melted for filling by supplying the filling melt to the concave / convex pattern of the wafer by a spin method or immersing the wafer in the filling melt tank. Replacement with a liquid is preferred.

  In addition, the number of particles larger than 0.5 μm in the particle measurement by the light scattering type submerged particle detector in the liquid phase in the filling treatment agent is obtained when the treatment agent is melted by heating to obtain a filling melt. It is preferable that 100 or less per 1 mL of the melt. If the number of particles larger than 0.5 μm is more than 100 per mL of the melt, the particles may cause damage to the pattern, which may cause a decrease in device yield and reliability. The number of particles larger than 0.5 μm may be 1 or more per 1 mL of the melt. In addition, since it is difficult to directly measure the number of particles in the melt, the measurement of particles in the melt in the present invention is performed by, for example, dissolving 1 mL of the melt in an organic solvent such as isopropyl alcohol in advance. On the other hand, measurement is performed using a commercially available measuring device in a light scattering type liquid particle measurement method using a laser as a light source, and the particle size of particles is light scattering based on PSL (polystyrene latex) standard particles. Means equivalent diameter.

  Moreover, it is preferable that the metal impurity content of each element of Na, Mg, K, Ca, Mn, Fe, and Cu in the said processing agent for filling is 100 mass ppb or less with respect to this processing agent total amount. The metal impurities of each element described above are all in the form of metal fine particles, ions, colloids, complexes, oxides and nitrides, whether dissolved or undissolved, in the treatment agent. If the metal impurity content is more than 100 mass ppb with respect to the total amount of the processing agent, there is a possibility that the junction leakage current of the device using the wafer increases, which may cause a decrease in device yield and reliability. is there. In addition, 0.01 mass ppb or more of each may be sufficient as said metal impurity content with respect to this processing agent total amount. The content of metal impurities in the filling treatment agent is such that all volatile components and evaporation components are volatilized and evaporated from a predetermined amount of the filling treatment agent, and the remaining residue is dissolved in hydrofluoric acid. The metal impurity content of can be measured by using a commercially available inductively coupled plasma mass spectrometer and the metal impurity content in the filling treatment agent can be calculated therefrom.

  In Patent Documents 1 to 4, there is a risk of inducing damage to the pattern when solidifying a solid in a concave portion of a wafer or depositing a sublimable substance in the concave portion, and the yield and reliability of devices using the wafer are reduced. However, in the present invention, it is not considered to mix particles that cause a decrease in the surface of the concave portion or metal impurities that may increase the junction leakage current of the device using the wafer. By setting the content of the particles and metal impurities within the above-described range, it is possible to improve the problems caused by them.

  In addition, the processing agent for filling includes a sublimation substance obtained by sublimation purification or distillation purification, a sublimation substance obtained by sublimation purification or distillation purification of a mixture of a sublimation substance and an organic solvent, and a sublimation substance obtained by sublimation purification or distillation purification in advance. And at least one selected from the group consisting of an organic solvent previously distilled and purified and 0.5 μm in particle measurement by a light scattering submerged particle detector in the liquid phase of the treatment agent When the treatment agent is melted by heating to obtain a filling melt, the number of larger particles is reduced to 100 or less per 1 ml of the melt, so that Na, Mg, K, Ca, Mn, Fe in the treatment agent are reduced. And it is preferable because the metal impurity content of each element of Cu and Cu is easily set to 100 mass ppb or less with respect to the total amount of the treatment agent. Sublimation purification is a method of purification using differences in sublimation and deposition temperatures of substances having sublimation properties.

  The sublimable substance is preferably at least one substance selected from the group consisting of naphthalene, paradichlorobenzene, tetrachlorodifluoroethane, camphor, and alkylamine carbonate.

  Further, in the cooling precipitation step, the melt is allowed to cool under atmospheric pressure, allowed to cool under pressure, and a coolant is brought into contact with a portion where the uneven pattern is not formed on the wafer. It is preferable to cool by at least one method selected from the group consisting of:

  In the cooling precipitation step, when a solid sublimable substance is deposited in the concave portion, if the organic solvent is present together with the solid sublimable substance in the concave portion, the organic solvent is evaporated and then the sublimation removing step. It is preferable to carry out. This is because the concave portion is filled and protected with a solid sublimable substance, so that the influence of capillary force when the organic solvent evaporates is suppressed.

  Further, in the sublimation removing step, the solid sublimable substance is sublimated at a temperature below room temperature to the melting point of the sublimable substance under atmospheric pressure, or at a temperature below the melting point of the sublimable substance under reduced pressure. Sublimation is preferred.

  Moreover, this invention is a processing agent for a filling containing the sublimable substance used with the cleaning method of the wafer in any one of said.

  The filling agent may contain 60% by mass or more of a sublimable substance and 40% by mass or less of an organic solvent. From the viewpoint of sufficiently filling the concave portion of the wafer with the sublimable substance and reducing the capillary force that may act on the concave portion of the wafer by the organic solvent contained, the filling treatment agent contains 95 mass of the sublimable substance. More preferably, the organic solvent is contained in an amount of 5% by mass or less. In addition, the filling treatment agent may be made of a sublimable substance from the viewpoint of sufficiently filling the concave portion of the wafer with the sublimable substance and preventing the capillary force from acting on the concave portion of the wafer.

  Moreover, it is preferable that the said organic solvent in the said processing agent for a filling is an organic solvent whose boiling point is higher than the temperature of the said melt for filling.

  In addition, the number of particles larger than 0.5 μm in the particle measurement by the light scattering type submerged particle detector in the liquid phase in the filling treatment agent was melted by heating to obtain a filling melt. The amount of metal impurities of each element of Na, Mg, K, Ca, Mn, Fe and Cu is 100 mass ppb or less with respect to the total amount of the treating agent for filling. Preferably there is.

  In addition, the processing agent for filling includes a sublimation substance obtained by sublimation purification or distillation purification, a sublimation substance obtained by sublimation purification or distillation purification of a mixture of a sublimation substance and an organic solvent, and a sublimation substance obtained by sublimation purification or distillation purification in advance. And at least one selected from the group consisting of a mixture of an organic solvent purified by distillation in advance.

  The sublimable substance is preferably at least one substance selected from the group consisting of naphthalene, paradichlorobenzene, tetrachlorodifluoroethane, camphor, and alkylamine carbonate.

  In the wafer cleaning method of the present invention, the cleaning liquid remaining in the concave portion of the wafer having a concavo-convex pattern on the surface is replaced with a filling melt obtained by melting a filling treatment agent containing a sublimation substance by heating, and after filling, This is a method in which a solid sublimable substance is precipitated by cooling and the solid sublimable substance is removed by sublimation, and the liquid such as the cleaning liquid is dried and removed from the recess without requiring special equipment or special conditions. It is possible to suppress the influence of the capillary force acting at the time, and as a result, there is an effect of reducing the pattern collapse. In addition, since the filling melt is a melt in which the filling treatment agent is melted within a temperature range of the melting point of the sublimable substance to be contained and the melting point + 25 ° C. or less, bubbles are generated in the melt. As a result, it can be filled while suppressing the action of capillary force.

The schematic diagram when the wafer 1 by which the surface was made into the surface which has the uneven | corrugated pattern 2 is seen. FIG. 2 shows a part of a cross section a-a ′ in FIG. 1. The figure which filled the melt for filling into the recessed part of the uneven | corrugated pattern 2. FIG. The figure which precipitated the solid of a sublimable substance in the recessed part of the uneven | corrugated pattern 2. FIG.

The present invention will be described in detail below. A preferred method for cleaning a wafer according to an embodiment of the present invention is as follows:
A cleaning step of cleaning the surface of the wafer having a concavo-convex pattern on the surface with a cleaning liquid;
A melt filling process, in which the cleaning liquid remaining in the recesses of the wafer after the cleaning process is replaced with a filling melt obtained by melting a filling processing agent containing a sublimation substance by heating, and filling.
A cooling precipitation step of precipitating a solid sublimable material by cooling the melt filled in the recess,
A sublimation removing step of removing the solid sublimable substance deposited in the concave portion by sublimation;

  The uneven pattern formed on the wafer surface is schematically shown in FIGS. FIG. 1 is a schematic view of a wafer 1 whose surface is a surface having a concavo-convex pattern 2, and FIG. 2 is a partial pattern of a convex portion 3 of a cross-section aa ′ in FIG. The recessed part 4 is shown. The width 5 of the concave portion of the pattern is indicated by the interval between the convex portion 3 and the convex portion 3 of the pattern as shown in FIG. 2, and is also referred to as “line width”. The aspect ratio of the convex portion 3 is expressed by dividing the height 6 of the convex portion 3 by the width 7 of the convex portion. Furthermore, the shape of the concavo-convex pattern may be a cylinder type used in a DRAM or the like.

  When the cleaning method considering the pattern collapse as in the cleaning method of the present invention is not performed, the pattern collapse in the cleaning process is such that the width 5 of the recess 4 is 70 nm or less, particularly 45 nm or less, and the aspect ratio is 4 or more. Tends to occur when the number is 6 or more. Moreover, even if the pattern is out of the above range, in the case of a pattern shape having a fragile portion in the convex portion, there is a possibility that the collapse of the pattern occurs due to the capillary force acting on the portion.

  An example of a method for forming an uneven pattern on the wafer surface is shown below. First, after applying a resist to the wafer surface, the resist is exposed through a resist mask, and the exposed resist or the resist that has not been exposed is removed by etching to produce a resist having a desired concavo-convex pattern. Moreover, the resist which has an uneven | corrugated pattern can be obtained also by pressing the mold which has a pattern to a resist. Next, the wafer is etched. At this time, the concave portion of the resist pattern is selectively etched. Finally, when the resist is removed, a wafer having a concavo-convex pattern on the surface is obtained.

  Regardless of the material of the concavo-convex pattern used in the cleaning method of the present invention and the concavo-convex pattern, as a wafer, as the wafer, a silicon wafer, a silicon carbide wafer, a wafer composed of a plurality of components containing silicon element, Various wafers such as sapphire wafers, various compound semiconductor wafers, and plastic wafers can be used. In addition, as for the material of the concavo-convex pattern, silicon-based materials such as silicon oxide, silicon nitride, polycrystalline silicon, and single-crystal silicon, metal-based materials such as titanium nitride, tungsten, ruthenium, tantalum nitride, and tin, and combinations of these materials Can be used.

  In the cleaning process, the wafer cleaning method is not particularly limited. As a wafer cleaning method, a wafer cleaning method represented by spin cleaning, in which a wafer is cleaned one by one by supplying a cleaning liquid near the rotation center while rotating the wafer while holding the wafer substantially horizontal, or a plurality of cleaning methods in a cleaning tank. One example is a batch system in which a single wafer is immersed and washed. The form of the cleaning liquid when supplying the cleaning liquid to the uneven pattern surface of the wafer is not particularly limited as long as it becomes liquid when held on the uneven pattern surface, and examples thereof include liquid and vapor. .

  The cleaning liquid in the cleaning step is at least one of an aqueous cleaning liquid mainly containing water or a cleaning liquid A different from the aqueous cleaning liquid. The cleaning liquid A is an organic solvent or a mixture of an aqueous cleaning liquid and an organic solvent. In addition, the aqueous cleaning liquid may be replaced with the cleaning liquid A after the wafer surface on which the concavo-convex pattern is formed is cleaned with the aqueous cleaning liquid. In particular, it is particularly preferable to use the cleaning liquid A made of an organic solvent in consideration of the substitution with the filling melt in the subsequent step.

  Examples of the water-based cleaning liquid include pure water or water in which at least one of organic solvents, acids, alkalis, surfactants, hydrogen peroxide, and ozone is mixed in water as a main component (for example, water content rate). Is 50% by mass or more).

  The organic solvent that may be used as the cleaning liquid A is not particularly limited, but hydrocarbons, esters, ethers, ketones, halogen-containing solvents, sulfoxide solvents, alcohols, polyhydric alcohols, polyhydric alcohols. Examples thereof include derivatives and nitrogen-containing compound solvents.

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

  Among the cleaning liquid A composed of the above organic solvent, if the organic solvent has a boiling point higher than the temperature of the filling melt in the melt filling step of the present invention, the organic solvent will boil at the time of replacement with the filling melt. Since the bubble which originates becomes difficult to generate | occur | produce and it becomes easy to suppress the effect | action of capillary force by this bubble as a result, it is especially preferable. However, those having a particularly high boiling point of the organic solvent tend to have a high viscosity, and as a result, the replacement with the filling melt tends to be difficult. Therefore, the upper limit of the boiling point of the organic solvent is particularly 250 ° C. preferable. In addition, if it has solubility in the filling melt used in the subsequent step, the cleaning liquid A remaining in the recesses does not phase separate from the filling melt that has flowed into the recesses. It is preferable because it can be more efficiently substituted by being dissolved in and incorporated into the solution. In addition, having solubility in the filling melt means that the cleaning liquid A is melted in the melt at any concentration without phase separation at the melt temperature in the melt filling step. . The preferred organic solvent varies depending on the sublimation substance used. For example, when naphthalene is used as the sublimation substance, the organic solvent includes cyclohexanone, diethylene glycol monoethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoester. Butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate, diethylene glycol dimethyl ether, Diethylene glycol ethyl ester Ether, diethylene glycol diethyl ether, diethylene glycol diacetate, triethylene glycol dimethyl ether, ethylene glycol diacetate, ethylene glycol diethyl ether, ethylene glycol dimethyl ether.

  In the melt filling step, the cleaning liquid remaining in the concave portion of the wafer is replaced with a filling melt obtained by melting a filling processing agent containing a sublimable substance by heating. The method for supplying the filling melt to the wafer surface in the melt filling step is not particularly limited. Typical filling melt supply method is a spin method in which the filling melt is supplied near the center of rotation while holding and rotating the wafer almost horizontally to replace and fill the wafer uneven pattern one by one. And a batch system in which a plurality of wafers are immersed in a filling melt tank to replace and fill the concavo-convex pattern of the wafers. FIG. 3 shows a state in which the concave / convex pattern 4 is filled with the filling melt 8.

  The sublimation substance contained in the processing agent for filling is not particularly limited as long as it has sublimability, and a substance having a sublimation point that becomes a gas from a solid to a liquid when heated at normal pressure, In addition, it refers to both a substance that becomes a gas from a solid through a liquid when heated at normal pressure, has a melting point, and gradually sublimates below the melting point. However, in the cleaning method using the filling melt of the present invention, considering the preparation of the filling melt, a substance that becomes a gas from a solid through a liquid, has a melting point, and uses a substance that gradually sublimates below the melting point. It is more preferable. Examples of sublimable substances having these properties include naphthalene, paradichlorobenzene, tetrachlorodifluoroethane, camphor, and alkylamine carbonates. The sublimable substance can be used as a filling melt melted by heating at a temperature equal to or higher than the melting point of each material. When a sublimable substance does not have a melting point at normal pressure and sublimates when heated, it can be melted by pressurization.

  The filling melt is a melt obtained by melting the filling treatment agent in a temperature range of the melting point of the sublimable substance to be contained and the melting point + 25 ° C. or less. At a temperature below the melting point of the sublimable substance, it is difficult to form a melt, that is, a liquid. On the other hand, at a temperature exceeding (melting point + 25 ° C.), the generation of bubbles in the melt increases due to evaporation of the sublimable substance. When bubbles are generated in the recess, a capillary force acts on the recess, leading to a collapse of the pattern. Furthermore, at temperatures exceeding (melting point + 25 ° C.), the sublimable substance evaporates too early, so that the sublimable substance evaporates from the melt while the wafer surface melt is cooled in the subsequent cooling step. As a result, a wafer surface that cannot be filled with the deposited solid sublimable substance is generated.

  The filling treatment agent may contain an organic solvent for the purpose of improving the leveling property when it is made into a melt. However, when the amount of the organic solvent is too large, it is not preferable because the pattern collapse is likely to occur due to the capillary force of the organic solvent that evaporates when the sublimable substance is deposited in the cooling deposition step. In addition, the higher the content of the organic solvent, the more likely the solid deposited in the cooling deposition step becomes porous or the less deposited solid, so that the effect of preventing pattern collapse that is the object of the present invention may be reduced. . Considering these, the amount of the organic solvent is preferably small, and the amount of the sublimable substance contained in the filling treatment agent is preferably 60% by mass or more, and more preferably 95% by mass or more.

  The type of the organic solvent is not particularly limited, but hydrocarbons, esters, ethers, ketones, halogen-containing solvents, sulfoxide solvents, alcohols, polyhydric alcohols, polyhydric alcohol derivatives, nitrogen-containing compounds A compound solvent etc. are mentioned.

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

  Among the above organic solvents, when the boiling point is higher than the temperature of the filling melt in the melt filling step of the present invention, bubbles derived from boiling of the organic solvent at the time of replacement with the cleaning liquid and filling Since it becomes difficult to generate | occur | produce and it becomes easy to suppress the effect | action of the capillary force by this bubble as a result, it is especially preferable.

  Thereafter, in the cooling precipitation step, the melt filled in the recesses is cooled to precipitate a solid sublimable substance, and the recesses are filled with the solid. FIG. 4 shows a state in which the concave portion 4 is filled with a solid 9 of a sublimable substance. The filled solid 9 suppresses pattern collapse. This cooling may be performed under atmospheric pressure or under pressure, or may be performed by bringing a coolant such as water into contact with a portion of the wafer where the uneven pattern is not formed.

  Finally, in the sublimation removal step, the solid sublimable substance is removed by sublimation. The removal in this case may be performed under atmospheric pressure or may be performed under reduced pressure. When a substance that has a melting point and gradually sublimates below the melting point is used as a sublimation substance when heated at normal pressure, it will become atmospheric pressure when heated at a temperature above the melting point of the sublimation substance. Below, the sublimable substance melts and becomes a liquid, and there is a possibility that the pattern collapses due to the capillary force when the liquid volatilizes. Therefore, in this case, it is preferable to sublime over time at a temperature from room temperature to a temperature lower than the melting point of the sublimable substance, or sublimation under reduced pressure. Under reduced pressure, a substance having a melting point when heated under atmospheric pressure may sublime.

  The cleaning method of the present invention may be cleaned in combination with other known cleaning methods that prevent collapse of the concavo-convex pattern. In particular, it is preferable to perform the cleaning method of the present invention in combination with a method of forming a water-repellent protective film on the surface of the concavo-convex pattern because the effect of preventing collapse of the concavo-convex pattern becomes higher. By holding a chemical solution for forming a water repellent protective film for forming a water repellent protective film on the uneven pattern surface of the wafer, the water repellent protective film can be formed on the uneven pattern surface. After forming a water-repellent protective film on the surface of the concavo-convex pattern, the cleaning process of the present invention may be performed, or after performing the cleaning process, a water-repellent protective film is formed on the surface of the concavo-convex pattern Then, it may be transferred to the melt filling step. In addition, after the sublimation removal process of the present invention, the water-repellent protective film is formed by, for example, irradiating the wafer surface with light, heating the wafer, exposing the wafer to ozone, irradiating the wafer surface with plasma, It can be removed by a treatment such as corona discharge on the surface.

  As the water-repellent protective film-forming chemical, any compound that forms a water-repellent protective film contained in the chemical (hereinafter referred to as “compound”) can be used as long as it can form a water-repellent protective film on the surface of the uneven pattern. The type of A) is also not particularly limited. As an example of compound A, for example, when the uneven pattern surface is a silicon-based material such as silicon oxide, silicon nitride, polycrystalline silicon or single crystal silicon, hexamethyldisilazane (HMDS), trimethylsilyldiethylamine (TMSDEA), tetramethyldisilane Examples include silane coupling agents such as silazane, trimethylsilyldimethylamine, octyldimethylsilyldimethylamine, trimethylsilylimidazole, trimethylchlorosilane, propyldimethylchlorosilane, octyldimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, trimethylmethoxysilane, and trimethylethoxysilane. . Further, when the surface of the concave / convex pattern is other than the above-mentioned silicon-based material, a substance that binds or adsorbs to the surface of the material and imparts water repellency to the surface of the concave / convex pattern may be used as the compound A.

  Examples of the solvent that may be used for dilution in the chemical solution for forming a water-repellent protective film include, for example, hydrocarbons, esters, ethers, ketones, halogen-containing solvents, sulfoxide solvents, alcohols, and polyhydric alcohol derivatives. An organic solvent such as a nitrogen-containing compound solvent is preferably used. Of these, hydrocarbons, esters, ethers, ketones, halogen-containing solvents, sulfoxide solvents, and polyhydric alcohol derivatives that do not have an OH group can be used to shorten the protective film on the surface of the concavo-convex pattern. It is more preferable because it can be formed in time.

[Appearance evaluation of melt for filling and melt filled in melt filling step]
The appearance of the filling melt was visually observed, and it was confirmed whether the melt was able to completely melt the filling treatment agent and whether bubbles were generated. In addition, in a wafer having a concavo-convex pattern on the surface, since there is no confirmation of defects such as bubbles or phase separation in the melt filling process, the same operation as in the melt filling process is performed on the smooth wafer surface. The appearance was observed in a state where the melt was filled on the wafer surface, and the presence or absence of the defects was confirmed.

[Evaluation of the number of particles larger than 0.5 μm in the treating agent for filling]
Since it is difficult to directly measure the number of particles in the filling treatment agent, the treatment agent is previously melted by heating to obtain a filling melt, and 1 mL of the melt is dissolved in isopropyl alcohol. The number of particles larger than 0.5 μm was measured using a light scattering type in-liquid particle measuring device (manufactured by Rion, KS-42AF type). The isopropyl alcohol used was previously purified by distillation and filter purification.

[Evaluation of metal impurity content in processing agent for filling]
All the volatile components and evaporating components are volatilized and evaporated from a predetermined amount of the filling treatment agent, the remaining residue is dissolved in hydrofluoric acid, and the content of metal impurities in the solution is measured by an inductively coupled plasma mass spectrometer ( Yokogawa Analytical Systems, Inc., Agilent 7500cs type) was used, and the metal impurity content in the processing agent for filling was calculated therefrom.

[Example 1]
(I-1) Preparation of Filling Melt Naphthalene (melting point: 80 ° C.), which is a sublimation substance, was previously purified by sublimation and used as a filling treatment agent. The filling treatment agent was melted at 85 ° C. in a beaker to prepare a filling melt tank. When the melt was visually observed, no foam was observed and the melt was a uniform liquid. The number of particles larger than 0.5 μm in the particle measurement by the light scattering liquid particle detector in the liquid phase in the filling treatment agent is determined by melting the treatment agent by heating and filling the filling melt. The number was 100 or less per 1 mL of the melt. Moreover, the metal impurity content of each element of Na, Mg, K, Ca, Mn, Fe, and Cu in the treatment agent was 100 mass ppb or less with respect to the treatment agent total amount. In addition, also in the examples and comparative examples after this example, the same purification was performed, and when the number of particles larger than 0.5 μm was melted by heating the treatment agent, the melt was used as a filling melt. It was confirmed that the metal impurity content of each element of Na, Mg, K, Ca, Mn, Fe, and Cu was 100 mass ppb or less with respect to the total amount of the processing agent.

(I-2) Cleaning Step A wafer with a smooth titanium nitride film (a silicon wafer having a titanium nitride layer with a thickness of 50 nm on the surface) is immersed in 1% by mass of hydrogen peroxide at room temperature for 1 minute, and then purified water After soaking for 1 minute, soaked in isopropyl alcohol (iPA) at room temperature for 1 minute, and then in propylene glycol monomethyl ether acetate (PGMEA) having a boiling point of 146 ° C. and soluble in naphthalene melt for 1 minute at room temperature. Soaked.

(I-3) Melt filling step The wafer with the titanium nitride film prepared in (I-2) was transferred from the PGMEA immersion tank to the filling melt tank and immersed in the filling melt for 3 minutes. At this time, since there were no bubbles on the surface of the wafer with the titanium nitride film and no phase separation was observed, it was confirmed that no trouble occurred in the melt filling step.

(I-4) Cooling Precipitation Step The wafer was pulled up from the filling melt, and the wafer was left to stand at room temperature and allowed to cool. Ten minutes later, when the appearance of the wafer surface was observed, solid naphthalene deposited uniformly on the entire wafer surface was observed by visual observation.

(I-5) Sublimation removal step The wafer with the solid naphthalene obtained in (I-4) was reduced to 1 mmHg in a vacuum oven and then heated to 80 ° C. All of the naphthalene sublimated and disappeared.

[Example 2]
It implemented on the same conditions as Example 1 except the temperature of the melt in a melt filling process having been 90 degreeC. When the filling melt was visually observed, no foaming was observed and the liquid was uniform. As in Example 1, when the wafer with the titanium nitride film was immersed in the filling melt in the melt filling step, there were no bubbles on the surface of the wafer and no phase separation was observed. It was confirmed that no defects occurred in the filling process. Further, when the cooling precipitation process was performed in the same manner as in Example 1, solid naphthalene deposited uniformly on the entire wafer surface was observed by visual observation. Further, it was confirmed that all the solid naphthalene on the wafer was sublimated and disappeared by the same sublimation removing process as in Example 1.

[Example 3]
Except that the temperature of the melt in the melt filling step was set to 100 ° C., the filling melt carried out under the same conditions as in Example 1 was visually observed. As a result, foaming was not observed and the liquid was uniform. As in Example 1, when the wafer with the titanium nitride film was immersed in the filling melt in the melt filling step, there were no bubbles on the surface of the wafer and no phase separation was observed. It was confirmed that no defects occurred in the filling process. Further, when the cooling precipitation process was performed in the same manner as in Example 1, solid naphthalene deposited on the entire wafer surface was observed by visual observation, but the amount of solid naphthalene deposited was small and partially visible. There was a part. This is presumably because the temperature of the melt was high and it took a long time to cool the melt, and as a result, the amount of the sublimable substance evaporated and decreased during the cooling precipitation process increased. Further, it was confirmed that all the solid naphthalene on the wafer was sublimated and disappeared by the same sublimation removing process as in Example 1.

[Example 4]
A mixture of naphthalene that had been purified by sublimation in advance and cyclohexanone that had been purified by distillation in advance (boiling point: 156 ° C.) at 80:20 (mass ratio) was used as a treating agent for filling. The filling agent was melted at 85 ° C. in a beaker. When this melt was visually observed, foaming was not seen and it was a uniform liquid. It implemented on the same conditions as Example 1 except having made the said melt into the melt for filling. As in Example 1, when a wafer with a titanium nitride film was immersed in the melt in the melt filling step, there were no bubbles on the surface of the wafer and no phase separation was observed. It was confirmed that no defects occurred in the process. Further, when the cooling precipitation process was performed in the same manner as in Example 1, solid naphthalene deposited uniformly on the entire wafer surface was observed by visual observation. Further, it was confirmed that all the solid naphthalene on the wafer was sublimated and disappeared by the same sublimation removing process as in Example 1.

[Example 5]
It implemented on the same conditions as Example 4 except the mass ratio of naphthalene and cyclohexanone of the processing agent for filling having been 55:45. When the filling melt was visually observed, no foaming was observed and the liquid was uniform. As in Example 4, when a wafer with a titanium nitride film was immersed in the melt in the melt filling step, there were no bubbles on the surface of the wafer and no phase separation was observed. It was confirmed that no defects occurred in the process. Further, when the cooling precipitation process was performed in the same manner as in Example 4, solid naphthalene deposited on the entire surface of the wafer was observed by visual observation, but the amount of solid naphthalene deposited was small and partially visible. There was a part. This is presumably because there was little sublimable substance precipitated from the melt during the cooling precipitation process due to the low content of the sublimable substance in the filling treatment agent. Further, it was confirmed that all the solid naphthalene on the wafer was sublimated and disappeared by the same sublimation removing process as in Example 4.

[Example 6]
As a cleaning process, a wafer with a smooth titanium nitride film (a silicon wafer having a titanium nitride layer having a thickness of 50 nm on the surface) is immersed in 1% by mass of hydrogen peroxide at room temperature for 1 minute, and then immersed in pure water for 1 minute. After that, it was immersed in isopropyl alcohol (iPA) at room temperature for 1 minute, and then immersed in cyclohexanone having a boiling point of 156 ° C. and soluble in naphthalene melt for 1 minute at room temperature. The other conditions were the same as in Example 1. As in Example 1, when a wafer with a titanium nitride film was immersed in the melt in the melt filling step, there were no bubbles on the surface of the wafer and no phase separation was observed. It was confirmed that no defects occurred in the process. Further, when the cooling precipitation process was performed in the same manner as in Example 1, solid naphthalene deposited uniformly on the entire wafer surface was observed by visual observation. Further, it was confirmed that all the solid naphthalene on the wafer was sublimated and disappeared by the same sublimation removing process as in Example 1.

[Example 7]
As a cleaning process, a wafer with a smooth titanium nitride film (a silicon wafer having a titanium nitride layer having a thickness of 50 nm on the surface) is immersed in 1% by mass of hydrogen peroxide at room temperature for 1 minute, and then immersed in pure water for 1 minute. After that, it was immersed in isopropyl alcohol (iPA) at room temperature for 1 minute, and then immersed in Novec HFE-7100 manufactured by Sumitomo 3M, which has a boiling point of 61 ° C. and soluble in naphthalene melt, at room temperature for 1 minute. The other conditions were the same as in Example 1. As in Example 1, when a wafer with a titanium nitride film was immersed in the melt in the melt filling step, bubbles were observed on the surface of the wafer although no phase separation was observed. Further, when the cooling precipitation process was performed in the same manner as in Example 1, solid naphthalene deposited uniformly on the entire wafer surface was observed by visual observation. Further, it was confirmed that all the solid naphthalene on the wafer was sublimated and disappeared by the same sublimation removing process as in Example 1.

[Example 8]
A filling treatment agent was prepared by mixing naphthalene which had been purified by sublimation in advance and Novec HFE-7100 (boiling point: 61 ° C.) manufactured by Sumitomo 3M, which had been previously purified by distillation, at 80:20 (mass ratio). The filling agent was melted at 85 ° C. in a beaker. When this melt was visually observed, although it was a uniform liquid, foaming was observed. It implemented on the same conditions as Example 1 except having made the said melt into the melt for filling. As in Example 1, when a wafer with a titanium nitride film was immersed in the melt in the melt filling step, bubbles were observed on the surface of the wafer although no phase separation was observed. Further, when the cooling precipitation process was performed in the same manner as in Example 1, solid naphthalene deposited uniformly on the entire wafer surface was observed by visual observation. Further, it was confirmed that all the solid naphthalene on the wafer was sublimated and disappeared by the same sublimation removing process as in Example 1.

[Example 9]
As a cleaning process, a wafer with a smooth titanium nitride film (a silicon wafer having a titanium nitride layer having a thickness of 50 nm on the surface) is immersed in 1% by mass of hydrogen peroxide at room temperature for 1 minute, and then immersed in pure water for 1 minute. Then, it was immersed in isopropyl alcohol (iPA) at room temperature for 1 minute, and then immersed in pure water having a boiling point of 100 ° C. and not soluble in naphthalene melt for 1 minute at room temperature. The other conditions were the same as in Example 1. As in Example 1, when a wafer with a titanium nitride film was immersed in the melt in the melt filling step, no phase bubbles were observed on the surface of the wafer, but phase separation was observed in part. Moreover, when the cooling precipitation process was performed like Example 1, the solid naphthalene which precipitated nonuniformly on the wafer surface by visual observation had adhered. Further, it was confirmed that all the solid naphthalene on the wafer was sublimated and disappeared by the same sublimation removing process as in Example 1.

[Comparative Example 1]
Naphthalene, which has been subjected to sublimation purification in advance, was used as a filling treatment agent, and the treatment agent was heated to 75 ° C., which is a temperature lower than the melting point of naphthalene, to obtain a filling melt. did not become.

[Comparative Example 2]
It implemented on the same conditions as Example 1 except the temperature of the melt in a melt filling process having been 110 degreeC. When the filling melt was visually observed, although it was a uniform liquid, foaming was observed. As in Example 1, when a wafer with a titanium nitride film was immersed in the melt for filling in the melt filling step, phase separation was not observed on the surface of the wafer, but it was confirmed that bubbles were present. did. Further, when the cooling precipitation process was performed in the same manner as in Example 1, it was confirmed by visual observation that about 50% of the wafer surface area had deposited solid naphthalene adhered, and it could not be filled sufficiently. It was done. This is presumably because the temperature of the melt was too high and it took a long time to cool the melt, and as a result, the amount of sublimable substances evaporated and reduced during the cooling precipitation process increased.

DESCRIPTION OF SYMBOLS 1 Wafer 2 Fine uneven | corrugated pattern 3 on the wafer surface 3 Pattern convex part 4 Pattern concave part 5 Concave width 6 Convex height 7 Convex width 8 Filling melt 9 Precipitated solid sublimation substance

Claims (17)

A cleaning step of cleaning the surface of the wafer having a concavo-convex pattern on the surface with a cleaning liquid;
A melt filling process, in which the cleaning liquid remaining in the recesses of the wafer after the cleaning process is replaced with a filling melt obtained by melting a filling processing agent containing a sublimation substance by heating, and filling.
A cooling precipitation step of precipitating a solid sublimable material by cooling the melt filled in the recess,
A method for cleaning a wafer having a sublimation removal step of removing a solid sublimable substance deposited in the recess by sublimation,
The wafer cleaning method, wherein the filling melt is a melt obtained by melting the filling treatment agent in a temperature range of not less than the melting point of the sublimable substance contained and not more than the melting point + 25 ° C. 2. The wafer cleaning method according to claim 1, wherein the filling treatment agent contains 60% by mass or more of a sublimable substance and 40% by mass or less of an organic solvent. The method for cleaning a wafer according to claim 1, wherein the organic solvent is an organic solvent having a boiling point higher than the temperature of the filling melt. 4. The wafer cleaning according to claim 1, wherein the cleaning liquid remaining in the concave portion of the wafer after the cleaning step is an organic solvent having a boiling point higher than the temperature of the filling melt. Method. The method for cleaning a wafer according to claim 1, wherein the cleaning liquid remaining in the concave portion of the wafer after the cleaning process is soluble in the filling melt. In the melt filling step, the cleaning liquid remaining in the recesses is filled with the filling melt by supplying the filling melt to the concave / convex pattern of the wafer by a spin method or immersing the wafer in the filling melt tank. 6. The wafer cleaning method according to claim 1, wherein the wafer is replaced. When the number of particles larger than 0.5 μm in the particle measurement by the light scattering type submerged particle detector in the liquid phase in the filling agent is melted by heating to form a filling melt. The number of metal impurities of each element of Na, Mg, K, Ca, Mn, Fe, and Cu in the processing agent is 100 mass ppb or less with respect to the total amount of the processing agent. The wafer cleaning method according to claim 1, wherein the wafer is cleaned. The processing agent for filling is obtained by sublimation-purifying or distillation-purifying a sublimable substance, sublimation-purified or distillation-purifying a mixture of a sublimation substance and an organic solvent, and 8. The wafer cleaning method according to claim 1, wherein the wafer cleaning method is at least one selected from the group consisting of a mixture of a distilled and purified organic solvent. 9. The sublimable substance is at least one substance selected from the group consisting of naphthalene, paradichlorobenzene, tetrachlorodifluoroethane, camphor, and alkylamine carbonate. The wafer cleaning method according to any one of the above. In the cooling deposition step, the melt is allowed to cool under atmospheric pressure, allowed to cool under pressure, and a coolant is brought into contact with a portion of the wafer where the uneven pattern is not formed. The wafer cleaning method according to claim 1, wherein the wafer is cooled by at least one method selected from the group. In the sublimation removing step, the solid sublimable substance is sublimated at a temperature below room temperature to the melting point of the sublimable substance under atmospheric pressure, or sublimated at a temperature below the melting point of the sublimable substance under reduced pressure. The wafer cleaning method according to claim 1, wherein the wafer is cleaned. The processing agent for filling containing the sublimation substance used with the cleaning method of the wafer in any one of Claims 1 thru | or 11. The filling treatment agent according to claim 12, wherein the filling treatment agent contains 60% by mass or more of a sublimable substance and 40% by mass or less of an organic solvent. 14. The filling treatment agent according to claim 12 or 13, wherein the organic solvent in the filling treatment agent is an organic solvent having a boiling point higher than the temperature of the filling melt. When the number of particles larger than 0.5 μm in the particle measurement by the light scattering type submerged particle detector in the liquid phase in the filling agent is melted by heating to form a filling melt. 100 or less per 1 mL of the melt, and the metal impurity content of each element of Na, Mg, K, Ca, Mn, Fe and Cu is 100 mass ppb or less with respect to the total amount of the processing agent for filling. The processing agent for filling according to any one of claims 12 to 14, characterized by these. The processing agent for filling is obtained by sublimation-purifying or distillation-purifying a sublimable substance, sublimation-purified or distillation-purifying a mixture of a sublimation substance and an organic solvent, and The filling treatment agent according to any one of claims 12 to 15, wherein the treatment agent is at least one selected from the group consisting of a mixture of a distilled and purified organic solvent. 17. The sublimable substance is at least one substance selected from the group consisting of naphthalene, paradichlorobenzene, tetrachlorodifluoroethane, camphor, and alkylamine carbonates. The filling treatment agent according to any one of the above.