JP2013098303A - Cleaning and drying agent, and method of cleaning and drying substrate using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a cleaning and drying agent which is used for cleaning and drying an extremely fine and precise pattern, releases no fluorine ion, and has no flash point; and a method of cleaning and drying a substrate.SOLUTION: The cleaning and drying agent contains fluorine-containing tertiary alcohol represented by the general formula (1) or fluorine-containing tertiary diol represented by the general formula (2).

Description

  The present invention relates to a cleaning / drying agent and a cleaning / drying method for cleaning inorganic members such as glass surfaces and metal surfaces. In particular, the present invention relates to a cleaning / drying agent for cleaning a substrate such as a semiconductor silicon wafer, a photomask, an optical disk, or a glass substrate for a liquid crystal display, and a method for cleaning and drying a substrate using the same.

  Integrated circuits such as semiconductor devices have been remarkably miniaturized. Photomask drawing patterns used for manufacturing integrated circuits on semiconductor devices by photolithography and the like, and patterns of black matrix (BM) substrates for liquid crystal displays Are also becoming finer. Hereinafter, a drawing pattern and its transfer pattern in which a circuit pattern or a pixel pattern is formed on a substrate are simply referred to as a pattern.

  In order to form a very fine pattern on a semiconductor device or photomask, for example, removal of dirt and polishing powder on a base plate such as a silicon wafer or a glass substrate, and then from a substrate with a metal thin film on which a Cr film or the like is formed Cleaning is necessary for the purpose of removal of dirt, removal of process residues such as resist, developing solution or etching solution in photolithography, and removal of foreign matters from the environment, such as dust generated from equipment and people, in these processes. . Furthermore, it is preferable that the substrate is dry at the end of cleaning, and it is important that there is no dry spot.

  The finer the microstructure on the device, the more advanced the cleaning method is required. For example, in cleaning using ion-exchanged water or pure water after removing particles (hereinafter sometimes simply referred to as water), if the draining after cleaning is poor, detergent residue due to residual detergent and silica on the substrate surface There is a risk that dry spots such as watermarks will be generated by dissolving and drying in pure water, and the fine structure may be broken due to the surface tension of pure water. There was a problem that it was difficult to clean the aspect ratio pattern.

  As a method for cleaning and drying the substrate using an organic solvent, a cleaning and drying method using isopropyl alcohol (2-propanol, hereinafter abbreviated as IPA) vapor (hereinafter sometimes abbreviated as IPA vapor cleaning) is known. In the IPA vapor cleaning, the substrate is put together with the holder in a tank in which the IPA vapor generated by heating the IPA is refluxed (hereinafter sometimes abbreviated as IPA vapor tank), and the IPA is condensed on the substrate surface. This is a washing and drying method in which foreign matter or dirt is washed out and dried while pulling up from the IPA vapor tank. Compared with air blow drying by air nozzle or air knife after hot pure water tank pull-up drying and warm pure water rinse, There is little generation of dry marks on the mark. Also, in the case of water-based cleaning in which the previous stage has a detergent tank, a rinsing tank, etc., water and IPA can be quickly replaced by transferring the substrate immediately after coming out of the final stage pure water tank to the IPA vapor tank, and drying. It is suitably employed as a drying method for preventing jimi.

  However, IPA vapor cleaning uses flammable IPA. If the IPA vapor tank becomes too large, it becomes difficult to circulate IPA in the IPA vapor tank. There were problems such as being unsuitable for the method.

  For example, Patent Document 1 discloses a substrate processing apparatus that can prevent the dissolution of an organic solvent vapor in pure water and suppress the transfer of particles, and uses IPA vapor to replace the pure water on the substrate surface. Is used. In any case, the cleaning and drying method using a flammable organic solvent has a problem that there is a need for fire prevention measures and explosion-proof equipment for the cleaning device.

  Further, in Patent Document 2, in order to solve the above problem, nonflammable 1,1,1,3,3,3-hexafluoro-2-propanol (hereinafter abbreviated as HFIP) is drained instead of IPA. A substrate drying apparatus used as an agent is disclosed. HFIP is a flame retardant fluorine-containing alcohol, has a moderate acid dissociation constant (pKa), and is expected to have a high cleaning effect.

  Cleaning methods that do not use a flammable organic solvent include a method in which carbon dioxide in a liquid state or a supercritical state is brought into contact with the substrate, and a method in which supercritical hydrofluorocarbon is brought into contact with the substrate.

  For example, a method using carbon dioxide in a liquid state or a supercritical state has a low surface tension of carbon dioxide and has an effect of cleaning an extremely fine pattern structure of a substrate, and is proposed as an alternative to aqueous cleaning. However, carbon dioxide in a liquid state or a supercritical state must be obtained with an expensive pressure device, which is difficult to use industrially and cannot be said to be an effective cleaning method.

  On the other hand, in the method using supercritical hydrofluorocarbon, the surface tension of supercritical hydrofluorocarbon is low and a cleaning effect can be expected. Hydrofluorocarbons (hereinafter sometimes abbreviated as HFC's) are chlorofluorocarbons (hereinafter referred to as CFC). This is a substitute CFC that is less environmentally friendly than the ozone layer and is known to be less effective for substrate cleaning. For example, Leblanc describes in "Non-Patent Document 1" that "they (HFCs) do not contain chlorine but are insufficient cleaning agents due to their high vapor pressure and low solubility". This is because, as described in Non-Patent Document 2, “(HFCs) are useful as carriers for other solvents and as rinsing agents, but the Kauributanol number (which is an indicator of solubility power) is about 10 “There is little or no solvent power for most soils involved by itself,” is supported by Kanegsberg.

  Non-Patent Document 1 and Non-Patent Document 2, even if cleaning is performed using only liquefied carbon dioxide, supercritical carbon dioxide, liquefied hydrofluorocarbon, or supercritical hydrofluorocarbon, the soil itself is not soluble, and substrate cleaning is performed. When performed, it was necessary to use a solvent that is highly soluble in dirt.

JP 2002-252201 A JP 2009-212445 A

The Evolution of Cleaning Solvents, Precision Cleaning, May, 1997, p.14 Precision Cleaning Without Ozone Depleting Chemicals ", Chemistry & Industry, October, 1996, p. 788

In order to enhance the cleaning effect in substrate cleaning, cleaning at −20 ° C. or higher is usually required, and the cleaning power increases as the temperature increases, and the substrate can be easily dried. However, when the stability of HFIP at high temperature and 150 ° C. was tested, it was found that fluoride ions were generated. This indicates that the carbon to which the OH group of 1,1,1,3,3,3-hexafluoro-2-propanol is bonded is bonded to two electron-withdrawing trifluoromethyl groups and bonded to the carbon. The hydrogen was estimated to have a higher acidity than hydrocarbon-based hydrogen, and was thought to be due to the concerted elimination of fluorine bound to β-carbon by the following reaction.

Eventually, HFIP becomes difluorovinyl ether. In the present invention, the fluoride ion means an anion (F ⁻ ) in which a fluorine atom obtains one electron and is ionized alone.

  Fluoride ions are known to cleave silyl (Si) -oxygen bonds, attacking the silicon substrate and peeling off the silicon from the silicon substrate to become dust. Since it can be a cause of structural defects, there is a problem that it is difficult to use HFIP as a cleaning / drying agent for silicon wafers and glass substrates that use semiconductor wafers, photomasks, or glass substrates for liquid crystal display devices.

In addition, there is a method of cleaning a silicon wafer in pure water under an alkaline atmosphere such as ammonia and then drying it. If an auxiliary agent that lowers the surface tension is added, a high aspect ratio pattern on the silicon wafer is formed. It is known to make it difficult to collapse. When HFIP was used as the auxiliary agent, as shown below, it was considered that HFIP reacts with ammonia to form a complex, and then the release of hydrogen atoms causes the generation of fluoride ions.

  Fluorine-containing secondary alcohols such as HFIP tend to generate fluoride ions by containing polarized OH sites and unstable hydrogen atoms at −20 ° C. or more, and silicon wafers, glass substrates for masks or glass substrates for liquid crystals There was a problem that it was difficult to use in the washing and drying process.

  The present invention solves the above-described problems, and provides a non-flammable cleaning / drying agent that has high cleaning ability and does not generate fluoride ions during cleaning, and a method for cleaning and drying a substrate that does not generate dry spots using the same. For the purpose.

  The fluorine-containing tertiary alcohol or fluorine-containing tertiary diol hardly generates fluoride ions at a cleaning temperature of −20 ° C. or higher. The problem was solved in the cleaning / drying agent containing the fluorine-containing tertiary alcohol or the fluorine-containing tertiary diol and the method of cleaning / drying the substrate using the same.

  In other words, in HFIP, it was considered that the generation of fluoride ions would be eliminated unless a hydrogen atom was directly bonded to a carbon atom to which a hydroxyl group was directly bonded. Therefore, the present inventors confirmed the stability of the fluorine-containing tertiary alcohol at 150 ° C., and found that generation of fluoride ions was not observed for a long time. Usually, fluorine compounds are known to have non-flammability when the fluorine content is large, specifically when the fluorine content is 40% by mass or more, and most fluorine-containing tertiary alcohols are non-flammable.

  Compared with HFIP, which is a fluorinated secondary alcohol, the fluorinated tertiary alcohol and the fluorinated tertiary diol do not generate fluoride ions. Excellent cleaning effect.

  In addition, by bringing the substrate into contact with a substrate whose surface was wet with pure water, it was easily replaced with water on the substrate, and a dry substrate free from dry spots was obtained.

    That is, this invention is comprised by the following inventions 1-8.

[Invention 1]
General formula (1):

(In the formula, R ^{1 to} R ³ are each independently a linear alkyl group having 1 to 7 carbon atoms or a cyclic alkyl group having 3 to 7 carbon atoms, and a part of hydrogen atoms in the alkyl group. Or all are substituted with fluorine atoms.)
Or a fluorine-containing tertiary alcohol represented by the general formula (2):

(In the formula, R ^{4 to} R ⁷ are each independently a linear alkyl group having 1 to 7 carbon atoms or a cyclic alkyl group having 3 to 7 carbon atoms, and a part of hydrogen atoms in the alkyl group. Or all are substituted with fluorine atoms.)
A cleaning / drying agent comprising a fluorine-containing tertiary diol represented by:

[Invention 2]
The cleaning / drying agent according to invention 1, wherein at least one of R ^{1 to} R ³ is a trifluoromethyl group, and at least two of R ^{4 to} R ⁷ are trifluoromethyl groups.

[Invention 3]
Furthermore, pure water, carbon dioxide, alcohol, nitrile, ketone, amide, sulfoxide, ether, hydrofluorocarbon, hydrofluoroether, at least one compound selected from the group consisting of hydrocarbons and aromatic hydrocarbons is added, The cleaning / drying agent of Invention 1 or Invention 2.

[Invention 4]
The cleaning / drying agent according to any one of Inventions 1 to 3, which is distilled after contacting with an ion exchange resin or mixing with a basic aqueous solution.

[Invention 5]
General formula (1):

(In the formula, R ^{1 to} R ³ are each independently a linear alkyl group having 1 to 7 carbon atoms or a cyclic alkyl group having 3 to 7 carbon atoms, and a part of hydrogen atoms in the alkyl group. Or all are substituted with fluorine atoms.)
Or a fluorine-containing tertiary alcohol represented by the general formula (2):

(In the formula, R ^{4 to} R ⁷ are each independently a linear alkyl group having 1 to 7 carbon atoms or a cyclic alkyl group having 3 to 7 carbon atoms, and a part of hydrogen atoms in the alkyl group. Or all are substituted with fluorine atoms.)
A cleaning and drying method for a substrate, wherein the substrate is brought into contact with a fluorine-containing tertiary diol represented by the formula, and the substrate is cleaned and dried at a temperature of −20 ° C. or higher and 200 ° C. or lower.

[Invention 6]
To the fluorine-containing tertiary alcohol represented by the general formula (1) or the fluorine-containing tertiary diol represented by the general formula (2), pure water, carbon dioxide, alcohol, nitrile, ketone, amide, sulfoxide, ether, The method of Invention 5, wherein at least one compound selected from the group consisting of hydrofluorocarbons, hydrofluoroethers, hydrocarbons and aromatic hydrocarbons is added and then contacted with the substrate.

[Invention 7]
The fluorine-containing tertiary alcohol represented by the general formula (1) or the fluorine-containing tertiary diol represented by the general formula (2) is contacted with an ion exchange resin or mixed with a basic aqueous solution and then distilled, The method of invention 5 or 6, wherein the contact is made.

[Invention 8]
The fluorine-containing tertiary alcohol represented by the general formula (1) or the fluorine-containing tertiary diol represented by the general formula (2) is contacted with an ion exchange resin or mixed with a basic aqueous solution and then distilled to obtain pure water. , Carbon dioxide, alcohol, nitrile, ketone, amide, sulfoxide, ether, hydrofluorocarbon, hydrofluoroether, at least one compound selected from the group consisting of hydrocarbons and aromatic hydrocarbons, and then contact with the substrate The method of invention 5 or 6.

  The cleaning / drying agent of the present invention contains a specific fluorine-containing tertiary alcohol or fluorine-containing tertiary diol, is nonflammable at a fluorine content of 40% by mass or more, and contains a semiconductor silicon wafer having a pattern formed on the surface It is suitably used as a cleaning / drying agent for photomasks, optical disks, glass substrates for liquid crystal displays, and the like. Further, fluoride ions are not generated even at a temperature of −20 ° C. or higher.

  Further, the specific fluorine-containing tertiary alcohol or fluorine-containing tertiary diol used in the substrate cleaning and drying method of the present invention can be easily replaced with water on the surface of the substrate coated with water, so that the final cleaning step is completed. By providing a step, it is possible to provide a dry substrate that does not have a dry spot after cleaning. The substrate cleaning / drying method of the present invention is suitably used for drying a substrate immediately before a metal thin film forming step such as Cr film formation and a resist coating step.

  Hereinafter, the fluorine-containing alcohol, fluorine-containing tertiary diol, other compounds, and the cleaning and drying method used in the cleaning and drying agent of the present invention and the substrate cleaning and drying method using the same will be described in order.

1. Fluorine-containing tertiary alcohol The fluorine-containing tertiary alcohol used in the cleaning / drying agent of the present invention and the substrate cleaning / drying method using the same is represented by the general formula (1):

(In the formula, R ^{1 to} R ³ are each independently a linear alkyl group having 1 to 7 carbon atoms or a cyclic alkyl group having 3 to 7 carbon atoms, and a part of hydrogen atoms in the alkyl group. Or all are substituted with fluorine atoms.)
It is represented by

  The fluorine-containing tertiary alcohol can suppress the generation of fluoride ions even under basic conditions because hydrogen is not bonded to carbon bonded to an OH group.

  In order for the fluorine-containing tertiary alcohol to have nonflammability, the fluorine-containing tertiary alcohol represented by the general formula (1) preferably contains 40% by mass or more of fluorine.

Specifically, in the general formula (1), all of R ^{1 to} R ³ are trifluoromethyl groups, 1,1,1,3,3,3-hexafluoro-2-trifluoromethyl-2- Propanol (also known as 1,1,1,3,3,3-hexafluoro-2- (trifluoromethyl) propan-2-ol, hereinafter sometimes referred to as PFTB), or ^{1 in} R ^{1 to} R ³ 1,1,1,3,3,3-hexafluoro-2-methylpropan-2-ol (hereinafter sometimes referred to as HFTB), one of which is a methyl group and the other two are trifluoromethyl groups And is preferably used in the cleaning / drying agent of the present invention and the method for cleaning and drying a substrate using the same.

2. Fluorine-containing tertiary diol The fluorine-containing tertiary diol used in the cleaning / drying agent of the present invention and the substrate cleaning / drying method using the same is represented by the general formula (2):

(In the formula, R ^{4 to} R ⁷ are each independently a linear alkyl group having 1 to 7 carbon atoms or a cyclic alkyl group having 3 to 7 carbon atoms, and a part of hydrogen atoms in the alkyl group. Or all are substituted with fluorine atoms.)
It is represented by

  The fluorine-containing tertiary diol can suppress generation of fluoride ions even under basic conditions because hydrogen is not bonded to carbon bonded with an OH group.

  In order for the fluorine-containing tertiary alcohol to have nonflammability, the fluorine content in the desired fluorine-grade diol represented by the general formula (2) is preferably 40% or more.

Specifically, in the general formula (2), 1,1,1,4,4,4-hexafluoro-2,3-bis (trifluoro) in which all of R ^{4 to} R ⁷ are trifluoromethyl groups. Methyl) -2,3-butanediol (hereinafter sometimes referred to as PFPi), and is preferably used in the cleaning / drying agent of the present invention and the substrate cleaning / drying method using the same.

3. Removal of fluoride ion In the synthesis of a fluorine-containing alcohol, when an alcohol containing no fluorine atom is fluorinated, there is a possibility of containing a fluoride ion. In the present invention, a fluorine-containing tertiary alcohol or fluorine-containing alcohol may be used. When the tertiary diol contains fluoride ions as contamination, the fluoride ions immerse the silicon wafer or the glass substrate. Therefore, the cleaning / drying agent of the present invention and the substrate cleaning / drying method using the same are used. It is preferable to remove fluoride ions before use.

As a result of intensive studies on the method for removing fluoride ions, the present inventors adsorb fluoride ions on the ion exchange resin even if fluoride ions are present in the fluorine-containing tertiary alcohol or fluorine-containing tertiary diol. Or by neutralization with a basic aqueous solution to form a salt. Specific examples of the basic aqueous solution include sodium bicarbonate water (sodium hydrogen carbonate, NaHCO ₃ aqueous solution). After the fluorine-containing tertiary alcohol or the fluorine-containing tertiary diol is washed several times with sodium bicarbonate water, distillation is performed. It is preferable to repeat several times, in which case the fluorine-containing tertiary alcohol or fluorine-containing tertiary diol is mixed with a solvent as a cleaning aid and a drying aid, and then washed with distilled water or ion-exchanged water and distilled. preferable.

4). Addition of other compounds Both the fluorine-containing tertiary alcohol and the fluorine-containing tertiary diol used in the cleaning / drying agent of the present invention and the method of cleaning / drying a substrate using the same are polarized compounds, and have a fluorine-carbon bond. Since the compound which has it is lipophilic, it is effective in removing both aqueous stains containing ionicity and oily stains adhering to the substrate. Further, fluorine-containing tertiary as an auxiliary agent for adjusting viscosity or melting point, further improving cleaning ability, dissolving ionic and oily soils, or adjusting the drying speed to obtain quick-drying after cleaning Other compounds other than alcohol and fluorine-containing tertiary diol may be added as an additive.

  Examples of such compounds include pure water, carbon dioxide, alcohols, nitriles, amides, sulfoxides, ethers, hydrofluorocarbons, hydrofluoroethers, hydrocarbons or aromatic hydrocarbons, and these compounds include fluorine-containing tertiary compounds. The alcohol or fluorine-containing tertiary diol may be added alone or in combination.

 Specifically, the alcohol includes methanol, ethanol, n-propanol, isopropanol or ethylene glycol, the nitrile includes acetonitrile or benzonitrile, the ketone includes acetone, methyl ethyl ketone, diethyl ketone, methyl-n-propyl ketone, Examples include methyl-iso-propylketone, methyl-n-butylketone, or methyl-iso-butylketone, and amides include N, N-dimethylformamide, N, N-dimethylacetamide, or N, N-dimethylimidazolidinone. The sulfoxide includes dimethyl sulfoxide, the ether includes diethyl ether, diisopropyl ether, dibutyl ether, or tetrahydrofuran, and the hydrofluorocarbon includes ISO. 17: HFC-23, HFC-32, HFC-125, HFC-134a, HFC-143a, HFC-152a, HFC-227ea, HFC-236fa, HFC-245fa, HFC -365mfc, HFC-43-10mee or HFC-447ef, and the hydrofluoroether is represented by a refrigerant number defined in ISO 817: 2005, and HFE-245mc, HFE-143m, HFE-254pc, HFE-347pc- f, HFE-55-10 mec-fc, HFE-7100, HFE-7200, HFE-7300 or HFE-7600, and aromatic hydrocarbons include benzene, toluene, xylene, mesitylene, perfluorobenzene, hydrocarbons The pig , Pentane, hexane or heptane and the like, it is preferable to use at least one compound selected from these compounds.

  Among these compounds, a high content of combustible compounds belonging to hazardous materials under the Fire Service Law is not preferable because it is contrary to the gist of the present invention to obtain a flame-retardant cleaning / drying agent. Therefore, when the compound used as an additive is flammable belonging to a dangerous substance under the Fire Service Law, the amount of addition is the fluorine-containing tertiary alcohol in the cleaning / drying agent of the present invention and the substrate cleaning / drying method using the same. 0.1 mass% or more and 200 mass% or less are preferable on the basis of fluorine-containing tertiary diol, More preferably, it is 0.5 mass% or more and 50 mass% or less. Specifically, it is preferably 0.001 g or more and 2 g or less, more preferably 0.005 g or more and 0.5 g or less, with respect to 1 g of fluorine-containing tertiary alcohol or fluorine-containing tertiary diol. If the addition amount is less than 0.1% by mass, the above-described addition effect cannot be obtained, and if it exceeds 200% by mass (twice), the flash point is lowered and combustibility becomes unfavorable.

  Hydrofluorocarbons and hydrofluoroethers often have no flash point due to the effect of fluorine content, and even if they are high, they often do not belong to dangerous materials under the Fire Service Law. The amount of the hydrofluorocarbon-based compound or hydrofluoroether compound that does not belong to a hazardous material under the Fire Service Law is arbitrary in the cleaning / drying agent and the cleaning method of the present invention, but fluorine-containing tertiary alcohol or fluorine-containing tertiary diol is used. As a reference, 0.1 mass% or more and 1000 mass% or less are preferable, More preferably, it is 0.5 mass% or more and 500 mass% or less. Specifically, 0.001 g or more and 10 g or less, more preferably 0.005 g or more and 5 g or less is added to 1 g of fluorine-containing tertiary alcohol or fluorine-containing tertiary diol. When the addition amount is less than 0.1% by mass, the above-described addition effect cannot be obtained, and when it exceeds 1000% by mass (10 times), the cleaning performance due to the inclusion of the fluorine-containing tertiary alcohol or fluorine-containing tertiary diol. Deteriorates.

  Compounds other than those described above, i.e., pure water and carbon dioxide, do not have any flash point, and can be mixed in any proportion for the above purpose. The amount of water and carbon dioxide that can be mixed is a specific amount for each fluorine-containing tertiary alcohol or fluorine-containing tertiary diol compound, but 0% based on the fluorine-containing tertiary alcohol or fluorine-containing tertiary diol. It is preferably 1% by mass or more and 10000% by mass or less, and more preferably 0.5% by mass or more and 1000% by mass or less. Specifically, 0.001 g or more and 100 g or less, more preferably 0.005 g or more and 1 g or less is added to 1 g of fluorine-containing tertiary alcohol or fluorine-containing tertiary diol. When the addition amount is less than 0.1% by mass, the above-described addition effect cannot be obtained, and when it exceeds 10,000% by mass (100 times), the cleaning performance due to the inclusion of the fluorine-containing tertiary alcohol or fluorine-containing tertiary diol. Deteriorates.

5. Substrate cleaning / drying method The temperature at which the substrate is cleaned and dried using the cleaning / drying agent of the present invention is within the range where the fluorine-containing tertiary alcohol or fluorine-containing tertiary diol contained in the cleaning / drying agent of the present invention does not solidify. It can be adjusted as long as it is not solidified by adding the aforementioned additives. The cleaning effect improves as the cleaning temperature increases. However, when cleaning at a temperature exceeding the boiling point of the cleaning / drying agent composition of the present invention, consideration is given so that the cleaning / drying agent does not flow out of the apparatus such as a reflux tank. Thus, it is preferable to determine the upper limit. A preferable washing temperature is −20 ° C. or more and 200 ° C. or less, and more preferably 30 ° C. or more and 150 or less. When the cleaning temperature is less than −20 ° C., the cleaning effect is small, the substrate after cleaning is in a painted state, and there is a possibility that dirt adhesion and cleaning spots may occur, which is not practical. The cleaning desiccant easily flows out of the apparatus such as the reflux tank, and if the tank is used as a sealed tank, a rise in the pressure of the apparatus becomes a problem. The cleaning and drying may be performed at a constant temperature within the above temperature range, or after cleaning at a low temperature within the above temperature range, the substrate may be dried at a higher temperature.

  In the method for cleaning and drying a substrate according to the present invention, in order to improve the cleaning effect and facilitate the replacement of water with a fluorine-containing tertiary alcohol or fluorine-containing tertiary diol in drying, these are vapor phase-liquid phase. It is preferable to use a supercritical fluid that is at the critical point. In general, the temperature and pressure for making a cleaning / drying agent containing a fluorine-containing tertiary alcohol or fluorine-containing tertiary diol or a composition used for drying a supercritical fluid requires high temperature and high pressure, and those skilled in the art will know. Can be easily determined. Specifically, a supercritical fluid is a point on the phase diagram that indicates the limits of the temperature and pressure range where a phase transition between a gas phase and a liquid phase of a substance can occur. It refers to the state of matter.

  As described above, the cleaning / drying apparatus can be either an open system or a closed system. However, if the cleaning temperature exceeds the boiling point of the cleaning desiccant, the cleaning / drying apparatus can be refluxed or sealed. It is desirable to use system devices. When the temperature at the time of washing or drying does not exceed the boiling point of the composition of the washing and drying agent, either an open system or a closed system may be used.

  In the cleaning / drying agent of the present invention and the substrate cleaning / drying method using the same, the used cleaning / drying agent can be discarded by a predetermined method. After removal, it may be used again for washing and drying as a washing and drying agent. When using an additive having a different boiling point when reused, the fluorine-containing tertiary alcohol, fluorine-containing tertiary diol or addition contained in the cleaning / drying agent is added for the purpose of adjusting the composition of the cleaning / drying agent again. Any deficient product can be added to the recovered material and used again as a washing and drying agent.

  Hereinafter, specific examples of the cleaning / drying agent of the present invention and the method of cleaning / drying a substrate using the same will be described by way of examples. As for the method of cleaning and drying the substrate, the flame retardancy of the cleaning and drying agent and the superiority of the cleaning and drying performance are shown. In addition, the purity of the composition contained in the washing / drying agent was measured by gas chromatography and represented by area% with respect to other compounds. The present invention is not limited to the following examples.

First, as shown in Examples 1 to 3 and Comparative Example 1, each washing and drying agent was prepared. A commercially available fluorine ion trapping agent (trade name, halogen killer, manufactured by Vitec Co., Ltd.) was used. Halogen killer is expressed by the chemical formula MgxAly (OH) z.X.nH ₂ O (X is an anion root) and has a high anion adsorption exchange ability, and it is said that halogen ions can be efficiently removed. .

[Example 1]
3 g of a commercially available fluorine ion trapping agent (trade name, halogen killer, manufactured by V-Tech Co., Ltd.) and 1,1,1,3,3,3-hexafluoro-2- (trifluoromethyl) propane which is a fluorine-containing tertiary alcohol 2-ol was added to 300 g (hereinafter abbreviated as PFTB), and 30 g of pure water was added at 10 ° C. or lower. After stirring for 30 minutes at room temperature (20 ° C.), precision distillation was performed, and the product was recovered with a purity of 99.9% by area or more in gas chromatography at a yield of 267 g. The recovered PFTB was a colorless and transparent liquid. When the content of fluoride ion was measured by ion chromatography, it was confirmed that it was 10 ppb or less.

[Example 2]
Instead of PFTB, 300 g of 1,1,1,3,3,3-hexafluoro-2-methylpropan-2-ol (hereinafter abbreviated as HFTB), which is a fluorine-containing tertiary alcohol, like PTFB, is used. Then, the operation was performed in the same procedure as in Example 1, and the purity in gas chromatography was 99.9 area% or more and the yield was 244 g. The recovered HFTB was a colorless and transparent liquid. When the content of fluoride ions was confirmed by ion chromatography, it was confirmed to be 10 ppb or less.

[Example 3]
Instead of PFTB, fluorine-containing tertiary diol, 1,1,1,4,4,4-hexafluoro-2,3-bis (trifluoromethyl) butane-2,3-diol (hereinafter referred to as PFPi) The same procedure as in Example 1 was performed using 300 g, and the purity in gas chromatography was 99.9 area% or more and the yield was 220 g. The recovered PFPi was a colorless and transparent liquid. When the content of fluoride ions was confirmed by ion chromatography, it was confirmed to be 10 ppb or less.

[Comparative Example 1]
Instead of PFTB, HFIP (1,1,1,3,3,3-hexafluoro-2-propanol) 300 g, which is a fluorine-containing secondary alcohol, was used in the same procedure as in Example 1. The purity in gas chromatography was 99.9 area% or more and the yield was 280 g. The recovered HFIP was a colorless and transparent liquid. When the fluoride ion content was confirmed by ion chromatography, it was confirmed that 60 ppb was contained.

The structural formulas of PFTB, HFTB, PFPi, and HFIP used in the above examples and comparative examples are shown below.

Next, after precision distillation, PFTB (Example 1) and HFTB (Example 2) which are fluorine-containing tertiary alcohol, PFPi (Example 3) which is a fluorine-containing tertiary diol, and HFIP which is a fluorine-containing secondary alcohol. (Comparative Example 1) Each 30 mL was placed in a 50 mL stainless steel autoclave, sealed, and heated in an oil bath at 150 ° C. for 48 hours. After cooling to room temperature, the lid was opened and 5 mL of the contents were taken out. The remainder was heated at 150 ° C. for 48 hours, cooled to room temperature (20 ° C.) after heating, the lid was opened, and the contents were taken out. The content of the fluoride ion was measured by ion chromatography for the obtained contents. Table 1 shows the heat resistance evaluation results together with the coloring of the contents.

The measurement results of the fluoride ion content shown in Table 1 show that fluorine-containing tertiary alcohols (PFTB, HFTB) and fluorine-containing tertiary diols (PFPi) in which all the α-positions are bonded by a carbon substituent and have no carbon-hydrogen bond. ) Showed that fluoride ions were not liberated even when continuously heated at 150 ° C. Specifically, as shown in Examples 1 to 3 in Table 1, PFTB was 48 hours, 15 ppb, 96 hours, and 20 ppb. HFTB was 48 hours, 30 ppb, 96 hours, 46 ppb. PFPi was 48 hours, 18 ppb, 96 hours, 21 ppb. After 48 hours, no coloring was observed, and after 96 hours, only HFTB was colored slightly yellow, indicating high heat resistance.

  In comparison, HFIP, which is a fluorine-containing secondary alcohol having a hydrogen-carbon bond at the α-position carbon and a fluorine-carbon bond at the β-position carbon, releases fluoride ions by continuous heating at 150 ° C. . As shown in Comparative Example 1 of Table 1, they were 48 hours, 220 ppb, and 96 hours 397 ppb. Further, it was colored yellow after 48 hours and was colored brown after 96 hours. It has been found that when the cleaning desiccant contains fluoride ions in the order of several hundreds of ppb, the surface of the silicon wafer having a high aspect ratio pattern microstructure is damaged.

  From the results shown in Table 1, the fluorine content of the fluorine-containing tertiary alcohol (PFTB, HFTB) and fluorine-containing tertiary diol (PFPi) is 46 ppb (HFTB) even when continuously heated at 150 ° C. for 96 hours. It is found that it is effective to use the cleaning / drying agent containing the fluorine-containing tertiary alcohol and fluorine-containing tertiary diol of the present invention and the cleaning / drying method using the same in the cleaning and drying process of the silicon wafer. It was.

[Reference example]
Without adding the above-mentioned fluorine ion trapping agent (trade name, Halogen Killer, manufactured by Vitec Co., Ltd.), 100 g of pure water was added to 300 g of PFTB, and the lower layer separated into two layers after stirring was taken out using a separating funnel As a result of precision distillation, it was possible to recover the gas chromatography with a purity of 99.9% by area or more and a yield of 275 g. When the fluoride ion content was confirmed by ion chromatography, it was confirmed to be 500 ppb.

  That is, it was found that it was difficult to remove fluoride ions by the method of washing the fluorinated alcohol with pure water.

  The cleaning / drying agent and the substrate cleaning / drying method using the cleaning / drying agent of the present invention are suitably used in a cleaning-drying process for semiconductor silicon wafers, liquid crystal display devices, photomasks, and optical disk glass substrates.

  In recent years, in the manufacturing process by lithography of semiconductor devices whose structures have been miniaturized, in order to prevent pattern collapse after cleaning-drying in each process such as resist film formation, etching, resist peeling, etc., or A cleaning and drying method using a cleaning liquid to which a surfactant is added has been studied. The cleaning / drying agent and the method for cleaning / drying a substrate using the same according to the present invention can be preferably used because the cleaning / drying agent used for cleaning / drying can be a supercritical fluid.

  Moreover, the plating process in semiconductor device manufacture is the key to wiring, and the method for cleaning and drying a substrate of the present invention is effective in cleaning and drying in plating of a semiconductor device.

  The cleaning / drying agent and the method of cleaning / drying a substrate using the same according to the present invention are used in the deposition of inorganic compounds, deposition, electroplating, and chemical plating in the production of metal thin films, metal oxide films, and composite films. It is useful in washing and drying, which are processes or subsequent processes.

Claims (8)

General formula (1):

(In the formula, R ^{1 to} R ³ are each independently a linear alkyl group having 1 to 7 carbon atoms or a cyclic alkyl group having 3 to 7 carbon atoms, and a part of hydrogen atoms in the alkyl group. Or all are substituted with fluorine atoms.)
Or a fluorine-containing tertiary alcohol represented by the general formula (2):

(In Formula (2), R < ⁴ > -R < ⁷ > is respectively independently a C1-C7 linear alkyl group or a C3-C7 cyclic alkyl group, and the hydrogen atom in the said alkyl group Is partially or entirely substituted with a fluorine atom.)
A cleaning / drying agent comprising a fluorine-containing tertiary diol represented by: The cleaning / drying agent according to claim 1, wherein at least one of R ^{1 to} R ³ is a trifluoromethyl group and at least two of R ^{4 to} R ⁷ are trifluoromethyl groups.   Furthermore, pure water, carbon dioxide, alcohol, nitrile, ketone, amide, sulfoxide, ether, hydrofluorocarbon, hydrofluoroether, at least one compound selected from the group consisting of hydrocarbons and aromatic hydrocarbons is added, The cleaning / drying agent according to claim 1 or 2.   A cleaning / drying agent obtained by distillation after the cleaning / drying agent according to any one of claims 1 to 3 is brought into contact with an ion exchange resin or mixed with a basic aqueous solution. General formula (1):

(In the formula, R ^{1 to} R ³ are each independently a linear alkyl group having 1 to 7 carbon atoms or a cyclic alkyl group having 3 to 7 carbon atoms, and a part of hydrogen atoms in the alkyl group. Or all are substituted with fluorine atoms.)
Or a fluorine-containing tertiary alcohol represented by the general formula (2):

(In Formula (2), R < ⁴ > -R < ⁷ > is respectively independently a C1-C7 linear alkyl group or a C3-C7 cyclic alkyl group, and the hydrogen atom in the said alkyl group Is partially or entirely substituted with a fluorine atom.)
A cleaning and drying method for a substrate, wherein the substrate is brought into contact with a fluorine-containing tertiary diol represented by the formula, and the substrate is cleaned and dried at a temperature of −20 ° C. or higher and 200 ° C. or lower.   To the fluorine-containing tertiary alcohol represented by the general formula (1) or the fluorine-containing tertiary diol represented by the general formula (2), pure water, carbon dioxide, alcohol, nitrile, ketone, amide, sulfoxide, ether, 6. The method according to claim 5, wherein at least one compound selected from the group consisting of hydrofluorocarbons, hydrofluoroethers, hydrocarbons and aromatic hydrocarbons is added and then contacted with the substrate.   The fluorine-containing tertiary alcohol represented by the general formula (1) or the fluorine-containing tertiary diol represented by the general formula (2) is contacted with an ion exchange resin or mixed with a basic aqueous solution and then distilled, The method according to claim 5 or 6, wherein the contact is performed.   The fluorine-containing tertiary alcohol represented by the general formula (1) or the fluorine-containing tertiary diol represented by the general formula (2) is contacted with an ion exchange resin or mixed with a basic aqueous solution and then distilled to obtain pure water, After adding at least one compound selected from the group consisting of carbon dioxide, alcohol, nitrile, ketone, amide, sulfoxide, ether, hydrofluorocarbon, hydrofluoroether, hydrocarbon and aromatic hydrocarbon, contact with the substrate; 7. A method according to claim 5 or claim 6.