JP5648053B2 - Chemical solution for forming wafer pattern protective film, method for preparing chemical solution, and wafer processing method - Google Patents

Description

  The present invention is a water-repellent protective film that is effective in reducing the capillary force of the pattern portion in order to prevent the concave-convex pattern from falling down (also referred to as collapse) when cleaning the wafer surface on which a fine concave-convex pattern is formed. The present invention relates to a chemical solution for forming a liquid, a chemical solution preparation method, and a wafer processing method using the chemical solution preparation method.

  In the manufacture of semiconductor chips, a fine uneven pattern is formed on the silicon wafer surface through lithography, etching, and the like, and thereafter, cleaning is performed using water (pure water) in order to clean the wafer surface. The elements are in the direction of miniaturization, and the interval between the concave and convex patterns is becoming narrower. For this reason, the problem that the concavo-convex pattern collapses due to the capillary force generated when washing with water (pure water) and drying the water from the wafer surface is becoming more likely. This problem has become more prominent particularly in semiconductor chips having a pattern size of 20 nm and 10 nm in which the uneven pattern interval is narrower.

  As a method for cleaning the wafer surface while preventing the pattern from collapsing, Patent Document 1 discloses a method in which water remaining on the wafer surface is replaced with isopropanol and then dried. In Patent Document 2, after cleaning the wafer surface with water, a water-repellent protective film (this protective film is finally removed) is formed on the uneven pattern portion, and then rinsed with water and then dried. The method of doing is disclosed. This method is said to be effective even for patterns having an aspect ratio of 8 or more.

In addition, although not focusing on prevention of pattern collapse separately from these, as a method for cleaning a semiconductor wafer, Patent Document 3 immerses the wafer in a tank storing pure water, and then lifts the wafer from the tank. A method for exposing a wafer to a gas containing vapor of 1,1,1,3,3,3-hexafluoro-2-propanol for draining is disclosed.
JP 2003-45843 A Japanese Patent No. 4403202 JP 2009-212445 A

  The wafer cleaning method includes the steps of immersing the wafer in water, then pulling the wafer out of the water and exposing the wafer to chemical vapor. The wafer cleaning method includes a process of cleaning a plurality of wafers at a time. Although it is an effective method for increasing efficiency, it has been found that the following two problems need to be solved when applying to a cleaning method for forming a water-repellent protective film with a focus on prevention of collapse of the concavo-convex pattern.

1) The chemical solution for forming the water-repellent protective film should be easily vaporized. 2) The vaporized chemical solution and the water remaining on the wafer surface are compatible, and the water-repellent protective film is formed on the uneven pattern portion. Can form

  The present invention relates to cleaning of a wafer surface on which an uneven pattern is formed, and an object thereof is to provide a chemical solution that can be applied to this wafer cleaning method.

Liquid chemical for forming a protective film of a wafer pattern according to claim 1, when cleaning a silicon wafer having a fine irregular pattern on its surface, a chemical solution for forming a water-repellent protective film uneven pattern surface, hydrofluoroether 93.5 to 97.499% by mass of at least one fluorine-containing solvent selected from the group consisting of ether and hydrochlorofluorocarbons ;
2-5% by weight of propylene glycol monomethyl ether acetate ;
0.5-5% by mass of at least one silazane compound selected from the group consisting of hexamethyldisilazane and tetramethyldisilazane;
0.001 to 0.25% by mass of at least one acid selected from the group consisting of trifluoroacetic acid, trifluoroacetic anhydride, and trimethylsilyl trifluoroacetate
It is characterized by including.

1) Providing a chemical solution for forming a water-repellent protective film that is easy to evaporate, as described above in the section “Problems to be Solved by the Invention”. This solves the problem that water remaining on the surface of the wafer is compatible with each other and a water-repellent protective film can be formed on the concavo-convex pattern portion, which is suitable for the wafer cleaning method. In particular, the present invention is suitable for a wafer cleaning method including a step of immersing a wafer in water, then pulling the wafer out of water and exposing the wafer to chemical vapor. That is, in this cleaning method, when a silicon wafer having a concavo-convex pattern having a silicon compound such as silicon oxide, silicon nitride, or silicon is immersed in water, OH groups are introduced into the concavo-convex pattern surface including these layers. The Then, the wafer is lifted from the water and exposed to the atmosphere of the chemical solution vapor, so that the chemical solution vapor is dissolved in the water held in the uneven pattern portion.

  In this process, the silazane compound reacts with the OH group on the surface of the concavo-convex pattern to form a water repellent protective film on the surface of the concavo-convex pattern. Thereafter, the wafer is dried, and the water-repellent protective film is removed from the wafer by UV irradiation, ozone treatment, heat treatment or the like.

The method for preparing a chemical solution according to claim 2 is at least one selected from the group consisting of hydrofluoroether and hydrochlorofluorocarbon before mixing in the method for preparing a chemical solution according to claim 1. A fluorine-containing solvent of
Propylene glycol monomethyl ether acetate ;
At least one silazane compound selected from the group consisting of hexamethyldisilazane and tetramethyldisilazane;
By purifying at least one of at least one acid selected from the group consisting of trifluoroacetic acid, trifluoroacetic anhydride, and trimethylsilyl trifluoroacetate and a mixed liquid after mixing, the amount of water in the chemical liquid Is a method for preparing a chemical solution for forming a water-repellent protective film on the surface of the concavo-convex pattern, characterized in that the total amount of the chemical solution is 5000 mass ppm or less.

The wafer processing method according to claim 3 is a wafer processing method for processing a wafer with a chemical solution, wherein a vapor generation step of supplying an inert gas to the chemical solution to generate a vapor of the chemical solution, and a wafer are housed. A heating step of heating the inside of the chamber and a supply step of supplying the vapor of the chemical solution generated in the vapor generation step to the wafer surface.

The wafer processing method according to claim 4 is a wafer processing method for processing a wafer with a chemical solution, wherein a heating step for heating the inside of the chamber containing the wafer, a pressure reduction step for reducing the pressure inside the chamber, and the pressure reduction step, A supply step of supplying the chemical solution stored in the tank to the wafer surface due to a pressure difference in the chamber and the tank in which the chemical solution is stored according to claim 1.

  Since the chemical solution for forming a protective film for a wafer pattern of the present invention is easily vaporized and is excellent in compatibility with water, a water-repellent protective film can be efficiently formed on the surface of the concave / convex pattern of the wafer by a wafer cleaning method.

It is a figure which shows typically the example of an apparatus used when wash | cleaning a wafer using the chemical | medical solution of this invention. It is a figure which shows schematic structure of the 1st wafer processing apparatus for enforcing the wafer processing method of this invention. It is a figure which shows schematic structure of the 2nd wafer processing apparatus for enforcing the wafer processing method of this invention.

The chemical solution for forming a protective film of the wafer pattern of the present invention is a chemical solution for forming a water-repellent protective film on the surface of the concavo-convex pattern when cleaning a silicon wafer having a fine concavo-convex pattern on the surface,
93.5 to 97.499% by mass of at least one fluorine-containing solvent selected from the group consisting of hydrofluorocarbons, hydrofluoroethers, perfluorocarbons, hydrochlorofluorocarbons;
2 to 5% by mass of at least one glycol ether acetate selected from the group consisting of ethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate;
0.5-5% by mass of at least one silazane compound selected from the group consisting of hexamethyldisilazane and tetramethyldisilazane;
It contains 0.001 to 0.25% by mass of at least one acid selected from the group consisting of trifluoroacetic acid, trifluoroacetic anhydride, trimethylsilyl trifluoroacetate, and dimethylsilyl trifluoroacetate.

  When the concentration of the silazane compound is low, the water-repellent protective film cannot be sufficiently formed. On the other hand, since the silazane compound is flammable, the risk of flammability increases as the concentration increases. Since the chemical solution for forming a protective film of the present invention is vaporized, it is important to reduce the risk of flammability. As mentioned above, the density | concentration of the said silazane compound is 0.5-5 mass%, and 0.7-4 mass% is more preferable.

  At least one acid selected from the group consisting of trifluoroacetic acid, trifluoroacetic anhydride, trimethylsilyl trifluoroacetate, and dimethylsilyl trifluoroacetate promotes the reaction between the silazane compound and the OH group on the surface of the concavo-convex pattern. To be successful. When the acid concentration is small, the promoting effect is small. However, since the acid reacts with the silazane compound to reduce the reactivity of the silazane compound, the storage stability of the protective film-forming chemical solution decreases when the acid concentration is high. For this reason, the density | concentration of the said acid is 0.001-0.25 mass%, and 0.005-0.25 mass% is especially preferable.

  The glycol ether acetate is water-soluble and is effective in enhancing the compatibility between the chemical solution for forming a protective film of the present invention and water. However, since the boiling point is high, it becomes difficult to vaporize the chemical solution when the concentration is high. For this reason, the density | concentration of the said glycol ether acetate is 2-5 mass%, and 2.5-4 mass% is more preferable.

  The fluorinated solvent has low flammability (that is, high flash point) and low boiling point. For this reason, when the concentration is high, the protective film-forming chemical solution has low flammability (that is, the flash point becomes high), and can be vaporized safely. However, if the concentration is too high, the concentrations of the silazane compound, the acid, and the glycol ether acetate are lowered. For this reason, a density | concentration is 93.5-97.499 mass%, and 94.0-97.0 mass% is more preferable.

  The method for preparing a chemical solution for forming a protective film of the present invention comprises a step of mixing the fluorinated solvent, the ether acetate, the silazane compound, and the acid so as to have a desired ratio.

  The silazane compound and the acid may react to reduce the reactivity of the silazane compound. For this reason, when the silazane compound and the acid are mixed, it is preferable to dilute at least one of the silazane compound and the acid with the fluorine-containing solvent or the ether acetate so that the rapid progress of the reaction can be prevented. .

  In addition, the method for preparing a chemical solution of the present invention includes a step of mixing the fluorine-containing solvent, the glycol ether acetate, the silazane compound, and the acid so as to have a desired ratio. At least one of the fluorine solvent, glycol ether acetate, silazane compound, acid, and the mixed solution after mixing may be purified by an adsorbent such as molecular sieve or by distillation to remove moisture. The silazane compound and acid before mixing may be in a state containing a solvent (a fluorine-containing solvent, glycol ether acetate). All the solutions may be purified before mixing, or the solution after mixing may be purified.

  The water content in the chemical solution for forming a protective film is preferably 5000 ppm by mass or less, particularly preferably 1000 ppm by mass or less, more preferably 500 ppm by mass or less, based on the total amount of the chemical solution. The moisture content may be 50 mass ppm or more.

  In addition to the fluorine-containing solvent, the glycol ether acetate, the silazane compound, and the acid, the chemical solution for forming a protective film of the present invention contains other additives and the like as long as the object of the present invention is not impaired. May be. Examples of the additive include oxidizing agents such as hydrogen peroxide and ozone, and surfactants. In addition, when there is a material that cannot form a protective film with the silazane compound in a part of the uneven pattern of the wafer, a material that can form a protective film may be added to the material.

  As a method for cleaning a wafer having a fine concavo-convex pattern on the surface, a method using the chemical solution of the present invention will be described below. The wafer W on which the concavo-convex pattern surface is formed is introduced into a cleaning apparatus 1 as shown in FIG. Here, the concavo-convex pattern surface is formed by various concavo-convex pattern forming methods such as the RIE method, and a concavo-convex pattern interval of 45 nm or less and an aspect ratio of 5 or more are preferably used. The surface of the concave / convex pattern includes silicon, and the surface includes at least one of silicon oxide, silicon nitride, polysilicon, and single crystal silicon.

  The wafer W is held on the support material 4 by the holder 5 of the wafer W, and is immersed together with the support material 4 in the aqueous cleaning liquid 2 in the water cleaning tank 3. Here, the aqueous cleaning liquid 2 includes water or water in which at least one of an organic solvent, an acid, an alkali, and an oxidizing substance is mixed with water as a main component (for example, the water content is 50% by mass or more). To do. There may be a plurality of aqueous cleaning liquids 2. In consideration of the cleanliness, the aqueous cleaning liquid is preferably water or, when there are a plurality of water-based cleaning liquids, the last is water.

  For example, after being held in the aqueous cleaning liquid 2 for 0.5 to 10 minutes, the wafer W is pulled up together with the support material 4. At this time, the concave / convex pattern concave portion is in a state filled with the aqueous cleaning liquid. After the wafer W is pulled up from the aqueous cleaning liquid, the tank 3 is preferably discharged out of the apparatus 1 or closed and closed from the environment inside the apparatus 1.

  Thereafter, the protective film-forming chemical solution is vaporized by a device (not shown), and the vaporized protective film-forming chemical solution is introduced into the device 1 through piping or the like. Fill with steam. By appropriately maintaining this state, replacement of the vapor of the protective film forming chemical solution with the aqueous cleaning solution filled in the concave and convex pattern recesses occurs.

  Hydroxyl groups are generated on the surface of the concavo-convex pattern by the previous aqueous cleaning liquid, and a water-repellent protective film is formed by the reaction between the hydroxyl groups and the silazane compound. After the formation of the protective film, the wafer W is dried in the apparatus 1 or in a state of being taken out from the apparatus 1, and the water-repellent protective film is removed.

  The removal of the water-repellent protective film is a process of removing the water-repellent protective film by performing at least one treatment selected from irradiating the wafer surface with light, heating the wafer, and exposing the wafer to ozone. Is done. In this step, plasma irradiation, corona discharge, or the like may be used in combination.

  The degree of water repellency can be measured by the contact angle with water. However, in the case of a wafer having a fine concavo-convex pattern on the surface, since the pattern is very fine, the contact angle of the protective film itself formed on the concavo-convex pattern surface cannot be accurately evaluated. The contact angle of water droplets is evaluated by dropping several μl of water droplets on the sample (base material) surface as in JIS R 3257 “Test method for wettability of substrate glass surface”, and the angle between the water droplet and the substrate surface. It is made by measuring. However, in the case of a wafer having a pattern, the contact angle becomes very large. This is because a Wenzel effect and a Cassie effect occur, and the contact angle is affected by the surface shape (roughness) of the substrate, and the apparent contact angle of water droplets increases.

  Therefore, in the present invention, the chemical solution is applied to a wafer having a smooth surface, a protective film is formed on the wafer surface, and the protective film is formed on the surface of the wafer having a fine uneven pattern formed on the surface. It was considered and evaluated. In the present invention, as a wafer having a smooth surface, a silicon wafer having a thermal oxide film layer on the surface and a smooth surface was used.

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

[Evaluation method of wafer provided with chemical solution for forming protective film]
The following evaluations (1) and (2) were performed as methods for evaluating a wafer provided with a chemical solution for forming a protective film.

(1) Contact angle evaluation of the protective film formed on the wafer surface About 2 μl of pure water is placed on the surface of the wafer on which the protective film is formed, and the angle (contact angle) formed between the water droplet and the wafer surface is measured by a contact angle meter (Kyowa). It was measured by Interface Science: CA-X type). Here, the contact angle of the protective film in the range of 50 to 130 ° was determined to be acceptable (denoted as “◯” in the table).

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

Example 1
(1) Preparation of chemical solution for protective film formation As fluorine-containing solvent, 3M hydrofluoroether (Novec HFE-7100); 95.4 g, propylene glycol monomethyl ether acetate (PGMEA); 3 g as glycol ether acetate were mixed. Water was removed from the mixed solution by molecular sieve 4A (Union Showa) and purification was performed. Subsequently, hexamethyldisilazane [(H ₃ C) ₃ Si—NH—Si (CH ₃ ) ₃ ]; 1.5 g as a silazane compound, 1.5 g as an acid, trimethylsilyl trifluoroacetate [(CH ₃ ) ₃ Si-OC (O) CF ₃ ]; 0.1 g is mixed, and the water content in the liquid is 10 ppm by mass or less, the concentration of the fluorinated solvent: 95.4% by mass, the concentration of glycol ether acetate; 3 A protective film-forming chemical solution having a mass%, a silazane compound concentration of 1.5 mass%, and an acid concentration of 0.1 mass% was obtained. The water content in the chemical solution was measured with a Karl Fischer moisture meter (manufactured by Kyoto Electronics, ADP-511 type).

(2) Cleaning of wafer A silicon wafer with a smooth thermal oxide film (a Si wafer having a 1 μm thick thermal oxide film layer on the surface) is immersed in a 1% by mass hydrofluoric acid aqueous solution at room temperature for 2 minutes, and then immersed in pure water for 1 min. Soaked.

(3) Surface treatment with a protective film forming chemical on the wafer surface 100 ml of the protective film forming chemical prepared in “(1) Preparation of protective film forming chemical” is placed in a 1 liter beaker, and the beaker is heated with a heater. The chemical solution was boiled by heating. When the boiling was stabilized, the wafer prepared in the above “(2) Wafer cleaning” was placed in a beaker without being immersed in the chemical solution while being wetted with water, and the vapor of the chemical solution was supplied to the wafer. After maintaining this state for 3 minutes, the wafer was taken out and dried naturally.

When the obtained wafer was evaluated in the manner described in “Method for evaluating wafer provided with protective film forming chemical solution”, as shown in Table 1, the initial contact angle before the surface treatment was less than 10 °. However, the contact angle after the surface treatment was 80 °, which showed the effect of imparting water repellency. Further, the capillary force when water was held was 0.6 MN / m ² , and the capillary force was small.

Example 2
All were the same as Example 1 except that trifluoroacetic acid was used as the acid. As a result, as shown in Table 1, the initial contact angle before the surface treatment was less than 10 °, but the contact angle after the surface treatment was 78 °, which showed the effect of imparting water repellency. Moreover, the capillary force when water was held was 0.7 MN / m ² , and the capillary force was small.

Example 3
The procedure was the same as in Example 1 except that trifluoroacetic anhydride was used as the acid. As a result, as shown in Table 1, the initial contact angle before the surface treatment was less than 10 °, but the contact angle after the surface treatment was 80 °, which showed the effect of imparting water repellency. Further, the capillary force when water was held was 0.6 MN / m ² , and the capillary force was small.

Example 4
All were the same as Example 1 except that 1,2-dichloro-3,3,3-trifluoropropene (DCTFP) was used as the fluorine-containing solvent. As a result, as shown in Table 1, although the initial contact angle before the surface treatment was less than 10 °, the contact angle after the surface treatment was 82 °, which showed the effect of imparting water repellency. Further, the capillary force when water was held was 0.4 MN / m ² , and the capillary force was small.

Example 5
The same procedure as in Example 1 was conducted except that tetramethyldisilazane [(H ₃ C) ₂ Si (H) —NH—Si (H) (CH ₃ ) ₂ ] was used as the silazane compound. As a result, as shown in Table 1, although the initial contact angle before the surface treatment was less than 10 °, the contact angle after the surface treatment was 82 °, which showed the effect of imparting water repellency. Further, the capillary force when water was held was 0.4 MN / m ² , and the capillary force was small.

Example 6
All were the same as Example 5 except that trifluoroacetic acid was used as the acid. As a result, as shown in Table 1, the initial contact angle before the surface treatment was less than 10 °, but the contact angle after the surface treatment was 80 °, which showed the effect of imparting water repellency. Further, the capillary force when water was held was 0.6 MN / m ² , and the capillary force was small.

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

Comparative Example 2
All were the same as Example 1 except that the silazane compound concentration was 0.1 mass% and the fluorine-containing solvent concentration was 96.8 mass%. As shown in Table 1, the contact angle after the surface treatment was as low as 30 °, and the capillary force when water was retained was as high as 2.8 MN / m ² as shown in Table 1.

Comparative Example 3
Example 1 was the same as Example 1 except that the acid concentration was 0.0001% by mass and the fluorine-containing solvent concentration was 95.4999% by mass. As shown in Table 1, the contact angle after the surface treatment was as low as 36 °, and the capillary force when water was retained was as large as 2.6 MN / m ² .

  In addition, the apparatus which uses the chemical | medical solution prepared by the preparation method by this invention is not restricted to the washing | cleaning apparatus shown in FIG.

FIG. 2 is a diagram showing a schematic configuration of a first wafer processing apparatus for carrying out the wafer processing method of the present invention. The first wafer processing apparatus includes a chamber 10 and a tank 20.

A holding mechanism 11 is accommodated in the chamber 10 to hold the wafer W. A motor 12 is connected to the lower surface of the holding mechanism 11. When the motor 12 is driven to rotate, the holding mechanism 11 holding the wafer W rotates. A heater 13 for heating the wafer W is built in the holding mechanism 11.

  On the upper side of the holding mechanism 11, a cylindrical nozzle 14 facing the surface of the wafer W held by the holding mechanism 11 is provided. A plurality of holes (not shown) for supplying the chemical vapor to the surface of the wafer W are formed in the nozzle.

Connected between the chamber 10 and the tank 20 is a supply pipe 21 for supplying the vapor of the chemical solution from the tank 20 to the nozzle 14 in the chamber 10.

The tank 20 is connected to the downstream side of the chemical liquid supply pipe 22 for supplying the chemical liquid. Further, the downstream end of a nitrogen gas supply pipe 24 for supplying nitrogen gas, which is an inert gas, to the tank 20 is connected to the tank 20. When nitrogen gas is supplied into the chemical solution stored in the tank 20, the chemical solution is bubbled and chemical vapor is generated in the tank 20.

The wafer processing method using this first wafer processing apparatus is as follows.
First, the chemical solution is supplied to the tank 20 through the chemical solution supply pipe 22.

Next, nitrogen gas is supplied into the chemical solution stored in the tank 20 through the supply pipe 24. The chemical liquid is bubbled by the nitrogen gas, and chemical vapor is generated in the tank 20.

Next, driving of the motor 12 is started, and heating of the wafer W by the heater 13 is started. The heating temperature of the wafer W at this time is between room temperature and 80 ° C. The chemical vapor generated in the tank 20 is supplied to the chamber 10 and supplied from the nozzle 14 to the wafer W held by the holding mechanism 11. Thereby, since the surface of the wafer W is water-repellent by the chemical solution of the present invention, the fine pattern can be prevented from being collapsed by the surface tension.

Note that the downstream side of the cleaning liquid supply pipe 23 for supplying the cleaning liquid to the tank 20 is connected, and the cleaning liquid is supplied to the tank 20 at a timing different from that of the chemical liquid so that vapor is generated and supplied to the wafer. good.

FIG. 3 is a diagram showing a schematic configuration of a second wafer processing apparatus for carrying out the wafer processing method of the present invention. The difference from the first wafer processing apparatus shown in FIG. 2 is that the chemical liquid stored in the tank 20 is bubbled to generate chemical vapor, or the inside of the chamber 10 is decompressed, The only difference is whether the chemical vapor is supplied to the chamber 10 by utilizing the pressure difference. Therefore, in the second wafer processing apparatus, the decompression pipe 18 for decompressing the inside of the chamber 10 is connected to the side portion of the chamber 10. In the second wafer processing apparatus, the nitrogen gas supply pipe 24 (see FIG. 2) for supplying nitrogen gas to the tank 20 is not provided.

The wafer processing method using this second wafer processing apparatus is as follows.
First, the chemical solution is supplied to the tank 20 through the chemical solution supply pipe 22.
Next, the inside of the chamber 10 is first depressurized via the decompression pipe 18.

Next, driving of the motor 12 is started, and heating of the wafer W by the heater 13 is started. The heating temperature of the wafer W at this time is between room temperature and 80 ° C. Then, the chemical vapor generated in the tank 20 due to the pressure difference between the chamber 10 and the tank 20 is supplied to the chamber 10 and supplied from the nozzle 14 to the wafer W held in the holding mechanism 11. Thereby, since the surface of the wafer W is water-repellent by the chemical solution of the present invention, the fine pattern can be prevented from being collapsed by the surface tension.

Note that the downstream side of the cleaning liquid supply pipe 23 for supplying the cleaning liquid to the tank 20 is connected, and the cleaning liquid is supplied to the tank 20 at a timing different from that of the chemical liquid so that vapor is generated and supplied to the wafer. good.

W Semiconductor wafer 1 on which an uneven pattern surface is formed 1 Apparatus used when cleaning a wafer using the chemical solution of the present invention 2 Water-based cleaning solution 3 Water cleaning tank 4 Wafer W support material 5 Wafer W holder

Claims (4)

This is a chemical solution for forming a water-repellent protective film on the surface of the concavo-convex pattern when cleaning a silicon wafer having a fine concavo-convex pattern on the surface, and the chemical solution is concavo-convex as vapor after OH groups are introduced into the concavo-convex pattern surface. Supplied to the surface of the pattern,
93.5 to 97.499% by mass of at least one fluorine-containing solvent selected from the group consisting of hydrofluoroethers and hydrochlorofluorocarbons ;
2-5% by weight of propylene glycol monomethyl ether acetate ;
0.5-5% by mass of at least one silazane compound selected from the group consisting of hexamethyldisilazane and tetramethyldisilazane;
0.001 to 0.25% by mass of at least one acid selected from the group consisting of trifluoroacetic acid, trifluoroacetic anhydride, and trimethylsilyl trifluoroacetate
A chemical solution characterized by containing. A method for preparing a chemical solution for preparing the chemical solution according to claim 1, wherein
At least one fluorine-containing solvent selected from the group consisting of hydrofluoroethers and hydrochlorofluorocarbons ;
Propylene glycol monomethyl ether acetate ;
At least one silazane compound selected from the group consisting of hexamethyldisilazane and tetramethyldisilazane;
By purifying at least one of at least one acid selected from the group consisting of trifluoroacetic acid, trifluoroacetic anhydride, and trimethylsilyl trifluoroacetate and a mixed liquid after mixing, the amount of water in the chemical liquid The preparation method of the chemical | medical solution for forming a water-repellent protective film on the uneven | corrugated pattern surface characterized by making 5000 mass ppm or less into this chemical | medical solution total amount. In a wafer processing method for processing a wafer with a chemical,
A steam generation step of supplying an inert gas to the chemical liquid of claim 1 to generate a vapor of the chemical liquid;
A heating step for heating the inside of the chamber containing the wafer;
And a supplying step of supplying the vapor of the chemical solution generated in the vapor generating step to the wafer surface. In a wafer processing method for processing a wafer with a chemical,
A heating step for heating the inside of the chamber containing the wafer;
A decompression step of decompressing the chamber;
2. A wafer processing method comprising: a tank in which the chemical solution of claim 1 is stored by the pressure reducing step; and a supply step of supplying the chemical solution stored in the tank to the wafer surface due to a pressure difference in the chamber. .

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