JP2013042093A - Wafer cleaning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for cleaning a surface of a wafer having an uneven pattern, reducing pattern collapse by reducing an influence of capillary force acting on the uneven pattern.SOLUTION: A wafer cleaning method comprises the steps of: cleaning a surface of a wafer on which an uneven pattern is formed, by using a cleaning liquid; replacing the cleaning liquid remaining in recesses of the wafer after the cleaning step with a treatment liquid obtained by dissolving or melting a treatment agent for filling containing a sublimable material, to fill the recesses with the treatment liquid; depositing the solid sublimable material from the treatment liquid filled in the recesses; and removing the solid sublimable material deposited on the recesses by sublimation.

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 processing liquid filling step, in which the cleaning liquid remaining in the concave portion of the wafer after the cleaning process is replaced with a filling processing liquid in which a filling processing agent containing a sublimable substance is dissolved or melted, and then filled.
Precipitating a solid sublimable substance from the treatment liquid filled in the recess, a solid precipitation step,
A method for cleaning a wafer, comprising: a sublimation removing step of removing a solid sublimable substance deposited in the concave portion by sublimation.

  Since the processing liquid is in a state in which a processing agent for filling containing a sublimable substance is dissolved or melted, the cleaning liquid remaining in the concave portion of the concave / convex pattern of the wafer can be replaced with the processing liquid. The processing liquid for filling can be 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 solid deposition process tends to be porous or the deposited solid is less likely, 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 material 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 cleaning liquid remaining in the concave portion of the wafer after the cleaning process is soluble in the processing liquid for filling.

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

  Further, the number of particles larger than 0.5 μm in the particle measurement by the light scattering type in-liquid particle detector in the liquid phase in the filling treatment agent is obtained by dissolving or melting the filling treatment agent. It is preferable that the number is 100 or less per mL of the treatment liquid. If the number of particles larger than 0.5 μm exceeds 100 per 1 mL of the processing solution, there is a risk of causing damage to the pattern due to the particles, 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 treatment liquid. In addition, since it is difficult to directly measure the number of particles in the treatment liquid, the particle measurement in the filling treatment agent in the present invention is performed by, for example, dissolving 1 mL of the treatment liquid in an organic solvent such as isopropyl alcohol in advance. The solution is measured by using a commercially available measuring device in a light scattering type in-liquid particle measurement method using a laser as a light source. The particle size of the particle is based on PSL (polystyrene latex) standard particle standard. It means the light scattering equivalent diameter.

  Moreover, it is preferable that the metal impurity content of each element of Na, Mg, K, Ca, Mn, Fe, and Cu in the 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 dissolved or melted to obtain a treatment solution for filling, the number of larger particles is reduced to 100 or less per 1 mL of the treatment solution, and 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, the solid precipitation step may be performed by leaving the treatment liquid under atmospheric pressure, allowing it to cool under atmospheric pressure, leaving it under pressure, allowing it to cool under pressure, and unevenness in the wafer. It is preferable to carry out by at least one method selected from the group consisting of bringing a coolant into contact with a portion where no pattern is formed.

  In the solid precipitation step, when a solid sublimable substance is precipitated in the concave portion, and the organic solvent is present in the concave portion together with the solid sublimable substance, the organic solvent is evaporated and then the sublimation removal 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, it is preferable that the viscosity of the processing liquid for filling which melt | dissolved or melt | dissolved the processing agent for filling used in the said processing liquid filling process is 0.05-100 mPa * s in the temperature of the processing liquid of this processing liquid filling process. . It is preferable for the viscosity of the processing liquid to fall within the above range because the processing liquid for filling can be sufficiently filled in the concave portions of the concave / convex pattern of the wafer. When the viscosity is less than 0.05 mPa · s, it is difficult to handle due to dripping or the like, and as a result, the amount used may increase and the cost may increase. The reason why the viscosity becomes too low is that the viscosity is too low because the solvent content in the processing solution is too high, and the viscosity is too high when the sublimable substance is melted by heating. May become too low. Moreover, when the viscosity is more than 100 mPa · s, it is difficult to sufficiently fill the recess with a treatment liquid, which is not preferable. More preferably, it is 0.5-50 mPa * s.

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

  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 material 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.

  In addition, the number of particles larger than 0.5 μm in the particle measurement by the light scattering type in-liquid particle detector in the liquid phase in the filling treatment agent dissolves or melts the filling treatment agent, thereby filling the treatment solution. The amount of the metal impurities of each element of Na, Mg, K, Ca, Mn, Fe, and Cu is 100 mass ppb each with respect to the total amount of the processing agent for filling. The following is preferable.

  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, in the particle measurement by the light scattering liquid particle detector in the liquid phase in the filling agent. The number of particles larger than 0.5 μm is reduced to 100 or less per 1 mL of the treatment liquid when dissolving or melting the treatment agent for filling to obtain a treatment liquid for filling, Na, Mg, It is preferable because the metal impurity content of each element of K, Ca, Mn, Fe, and Cu is easily set to 100 mass ppb or less with respect to the total amount of the processing agent for filling.

  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, after the cleaning liquid remaining in the concave portion of the wafer having a concavo-convex pattern on the surface is replaced with a filling processing liquid in which a filling processing agent containing a sublimation substance is dissolved or melted, the filling is performed. This is a method for precipitating a solid sublimable substance and removing the solid sublimable substance by sublimation. When a liquid such as a cleaning liquid is removed from the recess by drying without requiring a special device or special conditions. It is possible to suppress the influence of the capillary force that acts on the film, and as a result, there is an effect of reducing the pattern collapse.

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 recessed part of the uneven | corrugated pattern 2 with the processing liquid for filling. The figure which filled the recessed part of the uneven | corrugated pattern 2 with the solid of the sublimable substance.

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 processing liquid filling step, in which the cleaning liquid remaining in the concave portion of the wafer after the cleaning process is replaced with a filling processing liquid in which a filling processing agent containing a sublimable substance is dissolved or melted, and then filled.
Precipitating a solid sublimable substance from the treatment liquid filled in the recess, a solid precipitation step,
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 substitution with the processing liquid for filling in the subsequent process.

  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 liquids A composed of the above organic solvents, if the cleaning liquid A is soluble in the processing liquid for filling used in the subsequent process, the cleaning liquid A remaining in the concave portion is in phase with the filling processing liquid that has flowed into the concave portion. It is preferable because substitution can be performed more efficiently by dissolving and taking in the treatment liquid without separation. In addition, having solubility in the treatment liquid for filling means that the cleaning liquid A is dissolved in the treatment liquid at any concentration without phase separation at the treatment liquid temperature in the treatment liquid filling step. .

  In the treatment liquid filling step, the cleaning liquid remaining in the concave portion of the wafer is replaced with a filling treatment liquid in a state where a filling treatment agent containing a sublimable substance is dissolved or melted. In addition, when using the above-mentioned filling treatment liquid in a state where the filling treatment agent is dissolved, the sublimable substance may be dissolved in the organic solvent at room temperature, or dissolved by heating to a temperature below the melting point of the sublimable substance. You may let them. In addition, the filling treatment liquid in a state where the filling treatment agent is melted is a treatment liquid obtained by melting at a temperature equal to or higher than the melting point of the sublimable substance to be contained. There is no particular limitation on the method for supplying the filling processing liquid to the wafer surface in the processing liquid filling step. The supply method of the filling processing liquid is typified by a spin method in which the filling processing liquid is supplied near the center of rotation while holding and rotating the wafer substantially 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 processing solution tank to replace and fill the uneven pattern of the wafers. FIG. 3 shows a state in which the concave / convex pattern 4 is filled with the processing liquid 8 for filling.

  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. Examples of sublimable substances having these properties include naphthalene, paradichlorobenzene, tetrachlorodifluoroethane, camphor, and alkylamine carbonates. The sublimable substance can be made into a treatment liquid for filling by dissolving in an organic solvent or melting by heating at a melting point or higher of each material. When the sublimable substance does not have a melting point at normal pressure and sublimates when heated, it can be melted by pressurization to form a treatment liquid.

  The processing agent for filling may contain an organic solvent for the purpose of improving leveling properties when used as a processing liquid. However, when the amount of the organic solvent is too large, it is not preferable because the pattern collapse easily occurs due to the capillary force of the organic solvent that evaporates when the sublimable substance is precipitated in the solid precipitation step. In addition, the higher the content of the organic solvent, the more likely the solid deposited in the solid 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.

  Thereafter, in the solid deposition step, a solid sublimable substance is deposited from the treatment liquid filled in the recess, and the recess is 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. In the solid deposition step, the solid sublimable substance may be precipitated by cooling the treatment liquid, or the solid sublimation substance may be precipitated by volatilizing the organic solvent contained in the treatment liquid. Also good. The 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, the process liquid filling step may be performed. 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.

DESCRIPTION OF SYMBOLS 1 Wafer 2 Fine concavo-convex pattern on wafer surface 3 Pattern convex part 4 Pattern concave part 5 Concave width 6 Convex height 7 Convex width 8 Filling treatment liquid 9 Precipitated solid sublimation substance

Claims (15)

A cleaning step of cleaning the surface of the wafer having a concavo-convex pattern on the surface with a cleaning liquid;
A processing liquid filling step, in which the cleaning liquid remaining in the concave portion of the wafer after the cleaning process is replaced with a filling processing liquid in which a filling processing agent containing a sublimable substance is dissolved or melted, and then filled.
Precipitating a solid sublimable substance from the treatment liquid filled in the recess, a solid precipitation step,
A method for cleaning a wafer, comprising a sublimation removing step of removing a solid sublimable substance deposited in the recess by sublimation. 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. 3. The wafer cleaning method according to claim 1, wherein the cleaning liquid remaining in the concave portion of the wafer after the cleaning process is soluble in the processing liquid for filling. In the processing liquid filling step, the cleaning liquid remaining in the recesses is supplied with the filling processing liquid by supplying the filling processing liquid to the concave / convex pattern of the wafer by a spin method or immersing the wafer in the filling processing liquid tank. 4. The wafer cleaning method according to claim 1, wherein the wafer is replaced. In the filling agent, the number of particles larger than 0.5 μm in the particle measurement by the light scattering type in-liquid particle detector in the liquid phase dissolves or melts the filling agent to obtain a filling treatment solution. The amount of metal impurities of each element of Na, Mg, K, Ca, Mn, Fe and Cu in the processing agent for filling is 100 or less per 1 mL of the processing solution. The wafer cleaning method according to claim 1, wherein each wafer has a mass of 100 ppb or less. 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 6. 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. The sublimable substance is at least one substance selected from the group consisting of naphthalene, paradichlorobenzene, tetrachlorodifluoroethane, camphor, and an alkylamine carbonate. The wafer cleaning method according to any one of the above. In the solid deposition step, the treatment liquid is allowed to stand under atmospheric pressure, allowed to cool under atmospheric pressure, allowed to stand under pressure, allowed to cool under pressure, and a concavo-convex pattern on the wafer. The wafer cleaning method according to claim 1, wherein the cleaning method is performed by at least one method selected from the group consisting of bringing a coolant into contact with a portion not formed. 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 viscosity of the treatment liquid for filling in which the treatment agent for filling used in the treatment liquid filling step is dissolved or melted is 0.05 to 100 mPa · s at the temperature of the treatment liquid in the treatment liquid filling step. A method for cleaning a wafer according to any one of claims 1 to 9. 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 10. The filling treatment agent according to claim 11, 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. In the filling agent, the number of particles larger than 0.5 μm in the particle measurement by the light scattering type in-liquid particle detector in the liquid phase dissolves or melts the filling agent to obtain a filling treatment solution. 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 processing agent for filling. The filling treatment agent according to claim 11 or 12, wherein the treatment agent is a filling agent. 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 11 to 13, which is at least one selected from the group consisting of a mixture of a distilled and purified organic solvent. 15. 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.