JP7407581B2 - Organic solvent solution of quaternary ammonium hydroxide - Google Patents

Description

The present invention relates to a processing liquid composition for semiconductor manufacturing based on an organic solvent solution of quaternary ammonium hydroxide.

Solutions containing quaternary ammonium hydroxide are used as developing solutions for photoresists (sometimes simply referred to as "resists") and modified photoresists (for example, after ion implantation processes) in the manufacturing process of semiconductor devices, liquid crystal display devices, etc. photoresist, photoresist after ashing, etc.), as a stripping solution and cleaning solution, and as a silicon etching solution.

For example, in a photoresist development process, a negative or positive photoresist containing a resin such as novolac resin or polystyrene resin is applied to the surface of the substrate, and a photomask for pattern formation is applied to the applied photoresist. The irradiated photoresist is cured or solubilized by irradiating it with light, and a photoresist pattern is formed by removing the uncured or solubilized photoresist using a developer. be done.

The formed photoresist pattern serves to selectively treat areas not covered by the photoresist pattern in subsequent processes (eg, etching, doping, ion implantation, etc.). Thereafter, the photoresist pattern that is no longer needed is removed from the substrate surface using a resist stripping solution after undergoing an ashing process as required. If necessary, the substrate is further cleaned with a cleaning solution to remove resist residue.

Conventionally, aqueous solutions of quaternary ammonium hydroxide have been used for these applications. However, when the photoresist pattern undergoes a process such as ion implantation, the photoresist pattern is altered and a carbonaceous crust is formed on its surface. A modified photoresist with a crust formed on its surface is not easy to remove with a conventional aqueous quaternary ammonium hydroxide solution. Furthermore, the ashing residue of the photoresist pattern also has properties close to carbonaceous, and is not easy to remove with a conventional aqueous quaternary ammonium hydroxide solution.

Therefore, in order to more effectively remove such modified photoresist or photoresist ashing residue, an organic solvent solution of quaternary ammonium hydroxide is used instead of an aqueous solution of quaternary ammonium hydroxide. It is proposed that. Compared to an aqueous solution, an organic solvent solution of quaternary ammonium hydroxide corrodes metal materials used for wiring and inorganic base materials such as Si, SiO _x , SiN _x , Al, TiN, W, and Ta. It is also advantageous in that it is difficult to use.

Patent No. 4673935 Patent No. 4224651 Patent No. 4678673 Patent No. 6165442 International publication 2016/163384 pamphlet International publication 2017/169832 pamphlet

From the viewpoint of improving the ability to remove ashing residues of modified photoresists or photoresists, and from the viewpoint of compatibility with metal materials and inorganic substrate materials, the amount of water in the organic solvent solution of quaternary ammonium hydroxide should be low. desirable. Further, from the viewpoint of increasing the manufacturing yield of semiconductor devices, it is desirable that the content of metal impurities in the organic solvent solution of quaternary ammonium hydroxide is low.

However, for example, tetramethylammonium hydroxide (TMAH), which is a type of quaternary ammonium hydroxide, can be used in an aqueous solution with a concentration of 2.38 to 25% by mass, or as a crystalline solid of TMAH pentahydrate (purity 97 to 98%). However, anhydrous TMAH that is substantially free of water is not commercially available.

Generally, quaternary ammonium hydroxide is produced by electrolyzing an aqueous solution of a quaternary ammonium halide such as tetramethylammonium chloride (TMAC) (electrolytic method). Through this electrolysis, halide ions, which are counter ions of quaternary ammonium ions, are exchanged with hydroxide ions, and an aqueous solution of quaternary ammonium hydroxide is produced. For example, the concentration of a TMAH aqueous solution produced by an electrolytic method is usually about 20 to 25% by mass. According to the electrolytic method, it is possible to produce a highly pure quaternary ammonium hydroxide aqueous solution in which the content of metal impurities is approximately 0.1 mass ppm or less for each metal, and especially for TMAH, the content of metal impurities is It is possible to produce a highly pure quaternary ammonium hydroxide aqueous solution containing 0.001 mass ppm or less (that is, 1 mass ppb or less) of metal.

However, it is extremely difficult to obtain anhydrous quaternary ammonium hydroxide from an aqueous quaternary ammonium hydroxide solution. For example, when the concentration of the TMAH aqueous solution increases, a crystalline solid of TMAH pentahydrate (TMAH content: about 50% by mass) precipitates. Even if a crystalline solid of TMAH pentahydrate is heated, TMAH trihydrate (TMAH content: approximately 63% by mass) may be produced, but at the same time, TMAH decomposition (generation and release of trimethylamine) may occur. ) progresses.

A salt exchange method is known as a method for producing an organic solvent solution of quaternary ammonium hydroxide. For example, by mixing tetramethylammonium chloride (TMAC) and potassium hydroxide (KOH) in methanol, TMAH and potassium chloride (KCl) are generated, and KCl, which has low solubility in methanol, is precipitated. A TMAH methanol solution is obtained by filtering off the precipitated KCl. Although it is possible to obtain a TMAH methanol solution with a relatively low water content by the salt exchange method, the solution contains impurities such as KCl and water in an amount of about 0.5 to several mass %. As described above, by the salt exchange method, it is not possible to obtain a highly pure TMAH methanol solution useful in semiconductor manufacturing processes.

As another method for producing an organic solvent solution of quaternary ammonium hydroxide, Patent Document 1 describes a method for producing a concentrated solution of quaternary ammonium hydroxide in the form of hydrous crystals or an aqueous solution. A mixture is prepared by mixing class ammonium with a water-soluble organic solvent selected from the group consisting of glycol ethers, glycols, and triols, and the mixture is thin-film distilled under reduced pressure to obtain a distillate. A production method is described which is characterized by distilling off. Patent Document 1 states, for example, that a propylene glycol solution of TMAH (TMAH content: 12.6 mass%, water content: 2.0 mass%) was obtained by thin film distillation using a 25 mass% TMAH aqueous solution as a starting material. is listed.

However, when the present inventors tried the method described in Patent Document 1 using a high-purity quaternary ammonium hydroxide aqueous solution as a starting material, they found that the quaternary ammonium hydroxide obtained by thin film distillation was Metal impurities significantly exceeding 0.1 mass ppm were detected in the organic solvent solution. From the viewpoint of use in the manufacturing process of semiconductor devices, it is desirable that the metal impurity content in the organic solvent solution of quaternary ammonium hydroxide is at least 0.1 mass ppm or less for each metal.

As described above, a quaternary ammonium hydroxide organic solvent solution having a sufficiently high purity from the viewpoint of semiconductor manufacturing process applications has not yet been obtained.

An object of the present invention is to provide a processing liquid composition for semiconductor manufacturing based on a quaternary ammonium hydroxide organic solvent solution having a high level of purity useful for semiconductor manufacturing process applications.

The present invention includes the following embodiments [1] to [6].
[1] Quaternary ammonium hydroxide,
A processing liquid composition for semiconductor manufacturing, comprising a first organic solvent that dissolves the quaternary ammonium hydroxide,
The first organic solvent is a water-soluble organic solvent having a plurality of hydroxy groups,
The water content in the composition is 1.0% by mass or less based on the total amount of the composition,
The content of Na, Mg, Al, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn in the composition is each 100 mass ppb or less based on the total amount of the composition,
A processing liquid composition for semiconductor manufacturing, characterized in that the content of Cl in the composition is 100 mass ppb or less based on the total amount of the composition.

[2] The water content in the composition is 0.5% by mass or less based on the total amount of the composition,
The content of Na, Mg, Al, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn in the composition is each 50 mass ppb or less based on the total amount of the composition,
The processing liquid composition for semiconductor manufacturing according to [1], wherein the content of Cl in the composition is 80 mass ppb or less based on the total amount of the composition.

[3] The water content in the composition is 0.3% by mass or less based on the total amount of the composition,
The content of Na, Mg, Al, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn in the composition is each 20 mass ppb or less based on the total amount of the composition,
The processing liquid composition for semiconductor manufacturing according to [1] or [2], wherein the content of Cl in the composition is 50 mass ppb or less based on the total amount of the composition.

[4] The processing liquid composition for semiconductor manufacturing according to any one of [1] to [3], wherein the content of the quaternary ammonium hydroxide is 5.0% by mass or more based on the total amount of the composition.

[5] The content of the quaternary ammonium hydroxide is 2.38 to 25.0% by mass based on the total amount of the composition,
The processing liquid composition for semiconductor manufacturing according to any one of [1] to [3], wherein the quaternary ammonium hydroxide is tetramethylammonium hydroxide.

[6] The first organic solvent is one or more alcohols selected from dihydric alcohols and trihydric alcohols having a boiling point of 150 to 300°C and consisting of carbon atoms, hydrogen atoms, and oxygen atoms [1] to The processing liquid composition for semiconductor manufacturing according to any one of [5].

According to the present invention, it is possible to provide a processing liquid composition for semiconductor manufacturing based on a quaternary ammonium hydroxide organic solvent solution having a high level of purity useful for semiconductor manufacturing process applications.

FIG. 1 is a diagram schematically illustrating a falling film type thin film distillation apparatus 10A according to one embodiment. FIG. 3 is a cross-sectional view schematically illustrating details of an evaporation container 37 in the apparatus 10A. FIG. 3 is a diagram schematically illustrating a thin film distillation apparatus 10B according to another embodiment. FIG. 7 is a diagram schematically explaining a thin film distillation apparatus 10C according to another embodiment.

The above-described effects and advantages of the present invention will be made clear from the detailed description below. Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to these forms. Note that the drawings do not necessarily reflect exact dimensions. Further, in the figures, some symbols and hatching may be omitted. In this specification, unless otherwise specified, the notation "A to B" for numerical values A and B means "above A and below B". In such a notation, if a unit is attached only to the numerical value B, the unit shall also be applied to the numerical value A. Furthermore, the words "or" and "or" shall mean a logical sum unless otherwise specified. Regarding elements E ₁ and E ₂ , the notation "E ₁ and/or E ₂ " means "E ₁ or E ₂ , or a combination thereof", and the elements E ₁ , ..., E _N (N is 3 (integers above), the notation "E ₁ , ..., E _N-1 , and/or E _N " means "E ₁ , ..., E _N-1 , or E _N , or a combination thereof". do.

<1. Processing liquid composition for semiconductor manufacturing>
The processing liquid composition for semiconductor manufacturing of the present invention (hereinafter sometimes simply referred to as "composition") comprises: quaternary ammonium hydroxide; and a first organic solvent that dissolves the quaternary ammonium hydroxide. Contains. The first organic solvent is a water-soluble organic solvent having a plurality of hydroxy groups.

(1.1 Quaternary ammonium hydroxide)
Quaternary ammonium hydroxide (hereinafter sometimes referred to as "QAH") is an ionic compound composed of an ammonium cation with four organic groups bonded to a nitrogen atom and a hydroxide ion (anion). be. The composition of the present invention may contain only one type of quaternary ammonium hydroxide, or may contain two or more types of quaternary ammonium hydroxide. Examples of quaternary ammonium hydroxide include compounds represented by the following general formula (1).

一般式（１）において、Ｒ^１～Ｒ^４はそれぞれ独立に、ヒドロキシ基を有していてもよい炭化水素基であり、好ましくはヒドロキシ基を有していてもよいアルキル基である。レジスト及び変性レジストの除去性能及びエッチング性能等の観点からは、Ｒ^１～Ｒ^４は特に好ましくはヒドロキシ基を有していてもよい炭素数１～４のアルキル基である。Ｒ^１～Ｒ^４の具体例としては、メチル基、エチル基、プロピル基、ブチル基、２－ヒドロキシエチル基等を挙げることができる。

In general formula (1), R ¹ to R ⁴ are each independently a hydrocarbon group that may have a hydroxy group, preferably an alkyl group that may have a hydroxy group. From the viewpoint of resist and modified resist removal performance, etching performance, etc., R ¹ to R ⁴ are particularly preferably alkyl groups having 1 to 4 carbon atoms that may have a hydroxy group. Specific examples of R ¹ to R ⁴ include methyl group, ethyl group, propyl group, butyl group, and 2-hydroxyethyl group.

In general formula (1), R ¹ to R ⁴ may be the same or different from each other. In one embodiment, R ¹ to R ⁴ may be the same group, preferably an alkyl group having 1 to 4 carbon atoms. In other embodiments, R ¹ to R ³ may be the same group (first group), and R ⁴ may be a different group from R ¹ to R ³ (second group). In one embodiment, the first group and the second group can each independently be an alkyl group having 1 to 4 carbon atoms. In other embodiments, the first group can be a C1-4 alkyl group and the second group can be a C1-4 hydroxyalkyl group.

Specific examples of quaternary ammonium hydroxide include tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutylammonium hydroxide (TBAH), and trimethyl-2 -Hydroxyethylammonium hydroxide (also known as choline hydroxide) and the like.

Among these, TMAH is particularly preferable because it has particularly excellent resist and modified resist removal performance, etching performance, etc., is inexpensive, and has a wide range of uses. In addition, compounds in which part or all of the methyl group of TMAH is replaced with other groups such as ethyl group, propyl group, butyl group, such as TEAH, TPAH, TBAH, choline hydroxide, etc., have the ability to remove resists and modified resists. Although it is inferior to TMAH in etching performance, etc., it is sometimes preferred at semiconductor device manufacturing sites because it is not a poisonous substance and is compatible with the resist material used.

In one embodiment, the content of quaternary ammonium hydroxide in the composition may be 2.38-25.0% by weight. In one preferred embodiment, TMAH can be used as the quaternary ammonium hydroxide, and the content of TMAH in the composition can be 2.38 to 25.0% by mass based on the total amount of the composition. .

In one embodiment, the content of quaternary ammonium hydroxide in the composition may be preferably 5.0% by mass or more, more preferably 8.0% by mass or more, based on the total amount of the composition. When the content of quaternary ammonium hydroxide in the composition is at least the above lower limit, distribution costs of the composition can be saved. The upper limit of the content is not particularly limited, but may be 72% by mass or less in one embodiment, and 55% by mass or less in another embodiment. When the content of quaternary ammonium hydroxide in the composition is less than or equal to the above-mentioned upper limit, the increase in viscosity of the composition is suppressed, so handling, liquid feeding, mixing, etc. when using the composition are facilitated. becomes easier.

The concentration of quaternary ammonium hydroxide in the composition can be accurately measured using a potentiometric titration device, liquid chromatography, or the like. These measuring means may be used alone or in combination.

(1.2 First organic solvent)
The composition of the present invention contains, as a solvent, a first organic solvent that dissolves the quaternary ammonium hydroxide. The first organic solvent is a water-soluble organic solvent having a plurality of hydroxy groups. As the first organic solvent, one type of solvent may be used alone, or two or more types of solvents may be used in combination.

Since a water-soluble organic solvent having two or more hydroxy groups has a higher boiling point than water, it is possible to reduce the amount of water in the composition by distilling water off from the composition. The boiling point of the first organic solvent at a pressure of 0.1 MPa is preferably 150 to 300°C, more preferably 150 to 200°C. When the boiling point of the first organic solvent is 150° C. or higher, the first organic solvent is difficult to distill off when water is distilled off, making it easy to reduce the amount of water in the composition. Moreover, since the viscosity of the first organic solvent whose boiling point is not higher than the above upper limit is not so high, it is possible to improve the efficiency in distilling off water.

As the first organic solvent, one or more types selected from dihydric or trihydric alcohols having a boiling point of 150 to 300° C. consisting of carbon atoms, hydrogen atoms, and oxygen atoms, more preferably dihydric or trihydric aliphatic alcohols. alcohol can be preferably used. The melting point of the first organic solvent is preferably 25°C or lower, more preferably 20°C or lower.

Specific examples of preferred first organic solvents include ethylene glycol (boiling point 197°C), propylene glycol (boiling point 188°C), diethylene glycol (boiling point 244°C), dipropylene glycol (boiling point 232°C), and tripropylene glycol (boiling point 267°C). ), dihydric alcohols such as hexylene glycol (2-methyl-2,4-pentanediol) (boiling point 198°C); and trihydric alcohols such as glycerin (boiling point 290°C); and combinations thereof. Can be done.

Among these, alcohols having a hydroxyl group bonded to a secondary or tertiary carbon atom, such as propylene glycol, dipropylene glycol, tripropylene glycol, and hexylene glycol, are preferred from the viewpoint of storage stability of the composition. It can be preferably used as the organic solvent of 1. Among them, propylene glycol and hexylene glycol are particularly preferred from the viewpoint of the above-mentioned boiling point and storage stability of the composition, and are also preferred from the viewpoint of availability and cost.

(1.3 Second organic solvent)
Furthermore, the composition of the present invention may further contain an organic solvent other than the water-soluble organic solvent having a plurality of hydroxy groups (hereinafter sometimes referred to as a "second organic solvent") depending on the object to be treated. You can stay there. Examples of the second organic solvent include organic solvents known as organic solvents to be added to processing liquid compositions for semiconductor manufacturing. Preferred examples of the second organic solvent include water-soluble organic solvents (water-soluble monohydric alcohols) having only one hydroxyl group, such as methanol, ethanol, 1-propanol, 2-propanol, and n-butanol. Can be done. These water-soluble monohydric alcohols having only one hydroxy group can be preferably used, for example, to adjust the viscosity of the composition.

The proportion of the first organic solvent in the total organic solvent in the composition of the present invention is preferably 50% by mass or more, more preferably 75% by mass or more, and 95% by mass based on the total amount of organic solvent. % or more, and particularly preferably substantially 100% by mass. Here, the first organic solvent occupies "substantially 100% by mass" of all the organic solvents in the composition means that all the organic solvents in the composition consist only of the first organic solvent, or , means that the entire organic solvent in the composition consists of the above-mentioned first organic solvent and unavoidable impurities.

(1.4 Moisture content in composition)
The water content in the composition is 1.0% by mass or less, preferably 0.5% by mass or less, more preferably 0.3% by mass or less, based on the total amount of the composition. When the water content in the composition is below the above upper limit, it is possible to improve the removal performance of modified photoresists and ashing residues of photoresists, and to reduce corrosivity to metal materials and inorganic base materials. . The lower limit of the water content in the composition is not particularly limited, but may be, for example, 0.05% by mass or more.

The amount of water in a composition can be measured by gas chromatography, or by combining gas chromatography with a Karl Fischer moisture meter using the Karl Fischer method (hereinafter sometimes referred to as "Karl Fischer titration"). can also be measured. The Karl Fischer moisture meter allows measurement with simple operations, but the values measured by Karl Fischer titration may contain errors due to interfering reactions in the presence of alkali. On the other hand, according to gas chromatography, it is possible to accurately measure the water content regardless of the presence or absence of an alkali, but the measurement operation is not necessarily simple. For a solution having an alkaline concentration similar to that of the composition, a calibration curve is created in advance in which the water content measured by a Karl Fischer moisture meter is plotted on the vertical axis and the water content measured by gas chromatography is plotted on the horizontal axis, respectively. By correcting the measured value by the Karl Fischer moisture meter using the calibration curve, it is possible to accurately quantify the moisture content with a simple operation. Note that commercially available devices can be used as the gas chromatography and Karl Fischer moisture meter, respectively.

The operation of correcting the moisture content measured by the Karl Fischer moisture meter using a calibration curve can be preferably carried out by the following steps (1) to (6).
(1) The amount of water in the same organic solvent as that in the composition to be measured is measured by Karl Fischer titration. By adding water to the organic solvent, for example, five types of solutions (hereinafter sometimes referred to as "water/organic solvent solution") having different amounts of water are prepared. The amount of water added to the organic solvent is selected so that the amount of water in the composition to be measured is included in the range of the amount of water in the water/organic solvent solution. For example, if the water content in the composition to be measured is considered to be 0.05 to 5.0% by mass, then The amount of water added to the organic solvent can be determined so that there are five stages. In addition, the water content in the five types of water/organic solvent solutions prepared was measured by Karl Fischer titration, and the obtained value was in good agreement with the theoretical value calculated from the water content in the organic solvent and the amount of water added. It is desirable to confirm that there is a match.
(2) Each of the five types of water/organic solvent solutions prepared in (1) above was analyzed by gas chromatography (hereinafter sometimes referred to as "GC"), including the peaks of water and organic solvent. Get the GC chart. Taking the area of the water peak in the obtained GC chart as the vertical axis (Y), calculate the amount of water in the water/organic solvent solution (theoretical value calculated from the amount of water in the organic solvent and the amount of water added). Plot on the horizontal axis (X). By calculating a regression line using the least squares method with Y as the objective variable and X as the explanatory variable, a calibration curve (hereinafter referred to as "first calibration curve") that gives the water content from the area of the water peak in the GC chart is created. ) is obtained.
(3) As a standard solution, a concentrated aqueous solution (in a concentrated aqueous solution) of the same quaternary ammonium hydroxide (QAH) as in the composition to be measured is added to the same organic solvent as that in the composition to be measured. The QAH concentration of (can be as high as the available range, for example, 10 to 25% by mass) is added to prepare five types of mixed solutions. The amount of water in the organic solvent is accurately measured by Karl Fischer titration in (1) above. The QAH concentration in the QAH concentrated aqueous solution is accurately measured using a potentiometric automatic titrator. Accordingly, the water content in the QAH concentrated aqueous solution is also determined at the same time. The mixing mass ratio of the organic solvent and the QAH concentrated aqueous solution is selected so that the water content in the mixed liquid is in the same five levels as in (1) above.
(4) Analyze each of the five standard solutions prepared in (3) above by gas chromatography, and use the first calibration curve obtained in (2) above to calculate the area of the water peak in the GC chart. Obtain the water content in each standard solution. In general, the measured value of water content by GC is based on the theory of the water content in the standard solution calculated from the water content in the organic solvent, the water content in the QAH concentrated aqueous solution, and the mixing mass ratio of the organic solvent and the QAH concentrated aqueous solution. shows good agreement with the values.
(5) Measure the water content of each of the five standard solutions prepared in (3) above by Karl Fischer titration. For each standard solution, the water content measured by Karl Fischer titration is plotted on the vertical axis (Y), and the water content in the standard solution measured by GC in (3) above is plotted on the horizontal axis (X). Calibration that corrects the water content measured by Karl Fischer titration to the water content measured by GC for an organic solvent solution containing QAH and water by calculating a regression line using the least squares method with Y as the objective variable and X as the explanatory variable. A curve (hereinafter sometimes referred to as "second calibration curve") is obtained.
(6) Measure the water content of the actual composition to be measured by Karl Fischer titration, and use the second calibration curve obtained in (5) above to calculate the water content measured by GC. Correct the amount.

Note that it is not essential to measure the water content in the composition by Karl Fischer titration. By using the first calibration curve obtained by the above steps (1) and (2), the amount of water in the composition containing an alkali can be accurately measured by gas chromatography analysis.

The ratio (moisture content/quaternary ammonium hydroxide content) of the water content (unit: mass %) in the composition to the quaternary ammonium hydroxide content (unit: mass %) in the composition is , preferably 0.42 or less, more preferably 0.21 or less, still more preferably 0.10 or less. When the ratio is equal to or less than the above upper limit value, it becomes possible to further reduce the corrosivity to metal materials and inorganic base materials while maintaining or improving the removal performance of the modified photoresist and the ashing residue of the photoresist. The lower limit of the ratio is not particularly limited, but may be, for example, 0.0007 or more.

(1.5 Impurities in the composition)
The content of metal impurities in the composition is 100 mass ppb or less for each of Na, Mg, Al, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn based on the total amount of the composition. , preferably 50 mass ppb or less, more preferably 20 mass ppb or less. In this specification, the content of metal impurities in a composition means the total content of the metal elements, regardless of whether they are zero-valent metals or metal ions.

The content of chlorine impurities (Cl) in the composition is 100 mass ppb or less, preferably 80 mass ppb or less, and more preferably 50 mass ppb or less, based on the total amount of the composition. As used herein, the content of chlorine impurities in the composition means the total content of elemental chlorine. Note that in the composition, chlorine impurities usually exist in the form of chloride ions (Cl ⁻ ).

The content of metal impurities in the composition can be measured with a microanalysis device such as an inductively coupled plasma mass spectrometer (ICP-MS). Further, the content of chlorine impurities can be measured using a microanalysis device such as ion chromatography.

The ratio of the content of the metal impurities (unit: mass ppb) in the composition to the quaternary ammonium hydroxide content (unit: mass %) in the composition (content of metal impurities/quaternary hydroxide) The ammonium content is preferably 42 or less, more preferably 21 or less, still more preferably 10 or less for each of the above metal elements. When the ratio is equal to or less than the above upper limit value, it becomes possible to further increase the manufacturing yield of semiconductor devices while maintaining or improving the removal performance of the modified photoresist and the ashing residue of the photoresist. The lower limit of the ratio is not particularly limited, and is preferably as low as possible, but may be, for example, 0.0001 or more, taking into consideration the quantification limit of a metal impurity measuring device.

Ratio of the content of chlorine impurities in the composition (unit: mass ppb) to the quaternary ammonium hydroxide content (unit: mass %) in the composition (chlorine content/quaternary ammonium hydroxide content) ) is preferably 42 or less, more preferably 34 or less, even more preferably 21 or less. When the ratio is equal to or less than the above upper limit value, it becomes possible to further increase the manufacturing yield of semiconductor devices while maintaining or improving the removal performance of the modified photoresist and the ashing residue of the photoresist. The lower limit of the ratio is not particularly limited, and is preferably as low as possible, but may be, for example, 0.001 or more, taking into consideration the quantification limit of a chlorine impurity measuring device.

(1.6 Usage)
The composition of the present invention can be preferably used, for example, as a chemical solution such as a photoresist developer, a modified resist stripping solution and cleaning solution, and a silicon etching solution used in the manufacturing process of semiconductor devices.

In the field of semiconductor manufacturing, not only the above-mentioned various chemical solutions themselves but also concentrated liquids used to prepare the above-mentioned various chemical solutions by diluting with a solvent etc. are also referred to as processing solutions. In this specification, not only compositions having a concentration that can be used as they are as the various chemical solutions mentioned above, but also concentrated solutions that are subject to such dilution are considered to fall under the category of "processing liquid composition for semiconductor manufacturing." . The composition of the present invention can also be preferably used as the above-mentioned concentrated liquid. For example, by diluting (adjusting the concentration) the composition of the present invention with the first organic solvent, the second organic solvent, water, an aqueous quaternary ammonium hydroxide solution, or a combination thereof, a desired amount of water can be obtained. A chemical solution having a quaternary ammonium oxide concentration and a solvent composition can be obtained.

<2. Manufacturing (1)>
In one embodiment, the composition of the present invention can be used, for example, in a step (a) of removing water from the raw material mixture by thin film distillation of the raw material mixture using a thin film distillation apparatus (hereinafter referred to as "step (a)"). ) (hereinafter sometimes referred to as "the method according to the first embodiment").

(2.1 Raw material mixture)
The raw material mixture includes quaternary ammonium hydroxide (hereinafter sometimes referred to as "QAH"), water, and a first organic solvent that dissolves the quaternary ammonium hydroxide. The first organic solvent is a water-soluble organic solvent having a plurality of hydroxy groups.

(2.1.1 Quaternary ammonium hydroxide)
In the raw material mixture, as the quaternary ammonium hydroxide, the quaternary ammonium hydroxide described in Section 1.1 above can be used, and its preferred embodiments are also the same as above.

(2.1.2 First organic solvent)
In the raw material mixture, as the first organic solvent, a water-soluble organic solvent having a plurality of hydroxy groups as described in Section 1.2 above can be used, and its preferred embodiments are also the same as above. As the first organic solvent in the raw material mixture, one type of solvent may be used alone, or two or more types of solvents may be used in combination.

(2.1.3 Composition of raw material mixture)
Although the ratio of the above three components in the raw material mixture is not particularly limited, it is desirable that the amount of water be as small as possible. The quaternary ammonium hydroxides currently commercially available on an industrial scale are usually produced by electrolytic methods and are often distributed in the form of aqueous solutions. For example, the TMAH concentration of currently commercially available concentrated aqueous solutions of TMAH is typically on the order of 20-25% by weight. For example, currently commercially available concentrated aqueous solutions of TEAH, TPAH, TBAH, and choline hydroxide typically have a concentration of about 10 to 55% by weight. The raw material mixture can be prepared, for example, by mixing an aqueous quaternary ammonium hydroxide solution and the above-mentioned water-soluble organic solvent. The mixing ratio of quaternary ammonium hydroxide and water in the raw material mixture thus prepared reflects the concentration of the aqueous quaternary ammonium hydroxide solution used. From the viewpoint of reducing the amount of water to be distilled off in thin film distillation, it is desirable that the concentration of the quaternary ammonium hydroxide aqueous solution used for preparing the raw material mixture is high. For example, a crystalline solid such as TMAH pentahydrate can be used by dissolving it in a water-soluble organic solvent, but highly concentrated aqueous solutions of quaternary ammonium hydroxide and crystalline solids are often expensive. The amount of water in the raw material mixture can be determined by taking into consideration the cost of obtaining the quaternary ammonium hydroxide aqueous solution and the crystalline solid, the content of impurities, and the like.

The content of the first organic solvent in the raw material mixture is, for example, preferably 30 to 85% by mass, more preferably 40 to 85% by mass, still more preferably 40 to 80% by mass, particularly preferably may be 60-80% by weight.

The content of quaternary ammonium hydroxide in the raw material mixture is, for example, preferably 2.0 to 40% by mass, more preferably 2.0 to 30% by mass, and even more preferably 2.0% by mass based on the total amount of the raw material mixture. 25%, particularly preferably 5.0 to 10% by weight. The amount of water in the raw material mixture may be, for example, preferably 10 to 30% by mass, more preferably 15 to 30% by mass, based on the total amount of the raw material mixture.

It is desirable that the amount of impurities in the raw material mixture is small. In particular, metal impurities and non-volatile impurities such as chloride ions, carbonate ions, nitrate ions, and sulfate ions are difficult to remove by thin-film distillation, so it is desirable that they be small.

Metal impurities exist in solution as ions or fine particles. In this specification, metal impurities include both metal ions and metal particles. From the viewpoint of obtaining the high-purity composition described above, the content of each metal impurity in the raw material mixture is Na, Mg, Al, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and For each Zn, the amount may be preferably 50 mass ppb or less, more preferably 20 mass ppb or less, still more preferably 10 mass ppb or less, based on the total amount of the raw material mixture.

The content of chlorine impurities in the raw material mixture may be, for example, preferably 50 mass ppb or less, more preferably 30 mass ppb or less, still more preferably 20 mass ppb or less, based on the total amount of the raw material mixture.

The content of each metal impurity in the quaternary ammonium hydroxide aqueous solution used for preparing the raw material mixture is preferably 100 mass ppb or less, more preferably 1 mass ppb or less, based on the total amount of the aqueous solution. Furthermore, even when a crystalline solid raw material such as TMAH pentahydrate is used as the quaternary ammonium hydroxide source instead of an aqueous solution, the content of each metal impurity is 100 mass ppb or less based on the total amount of the crystalline solid raw material. It is preferable.

The content of each metal impurity in the first organic solvent used for preparing the raw material mixture is preferably 50 mass ppb or less, more preferably 10 mass ppb or less, based on the total amount of the first organic solvent. If the impurity content in the commercially available first organic solvent is high, the purity can be increased by distilling the first organic solvent alone.

The first organic solvent used to prepare the raw material mixture does not have to be an anhydrous solvent, but from the perspective of increasing the efficiency of thin film distillation, the amount of water in the first organic solvent used to prepare the raw material mixture is as follows: It is preferably 1% by mass or less, more preferably 0.5% by mass or less, based on the total amount of the first organic solvent.

(2.2 Step (a): Thin film distillation)
Step (a) is a step of removing water from the raw material mixture by subjecting the raw material mixture to thin film distillation using a thin film distillation apparatus. Thin film distillation involves forming a thin film of a raw material liquid under reduced pressure, heating the thin film, evaporating a part of it according to the vapor pressure of the components contained in the raw material liquid, and cooling and condensing the vapor. This is a method of separating the distillate and the residue (including the dissolved material). By subjecting the raw material mixture described above to thin film distillation, water can be distilled off from the raw material mixture and an organic solvent solution of quaternary ammonium hydroxide can be recovered as a residual liquid. A part of the organic solvent may be distilled off together with the water. The water (and part of the organic solvent) distilled off from the raw material mixture is recovered as a distillate. According to thin film distillation, water can be distilled off while suppressing thermal decomposition of quaternary ammonium hydroxide.

(2.2.1 Thin film distillation device)
In step (a), as the thin film distillation apparatus, known thin film distillation apparatuses such as a falling film type, centrifugal type, rotary type, blade type, and rising type can be used. Among these, a falling film type thin film distillation apparatus is used. can be particularly preferably used. FIG. 1 schematically shows a thin film distillation apparatus 10A (hereinafter sometimes referred to as "thin film distillation apparatus 10A" or simply "apparatus 10A") according to one embodiment that can be used in step (a). FIG. The apparatus 10A is a falling film short-stroke thin film distillation apparatus.

The thin film distillation apparatus 10A includes a raw material container 31 that stores a raw material mixture, an evaporator (evaporator) 37 in which distillation is actually performed, and a raw material pipe 33 that transfers the raw material mixture from the raw material container 31 to the evaporator 37. Equipped with. As shown in FIG. 1, a needle valve 32 is provided in the middle of the raw material pipe 33. The apparatus 10A further includes a residue recovery container 12 connected to the evaporation container 37 and receiving the distillation residue, a distillate recovery container 13 connected to the evaporation container 37 and receiving the distillate, and a distillation residue recovery container 13 connected to the evaporation container 37 and receiving the distillation residue. A glass pipe 8 for flow rate confirmation and a gear pump (liquid feeding pump) 10 (on the residual liquid side) installed in the middle of a flow path leading the distillate to the residual liquid recovery container 12, and a distillate recovery container for transporting the distillate from the evaporation container 37. 13, a glass pipe 9 for checking the flow rate and a gear pump (liquid pump) 11 (on the distillate side), a vacuum pump 15 that decompresses the inside of the evaporation container 37, and a A cold trap 14 is provided in the middle of a flow path leading to a vacuum pump 15.

The raw material mixture leaves the raw material container 31, passes through the needle valve 32 and the raw material piping 33, and flows into the evaporation container (evaporator) 37. The vacuum pump 15, needle valve 32, and (residue liquid side and distillate side) gear pumps (liquid feeding pumps) 10 and 11 maintain the inside of the system including the evaporation container 37 at a constant degree of vacuum. The raw material mixture in the raw material container 31 spontaneously flows into the raw material pipe 33 via the needle valve 32 due to the pressure difference between the vacuum degree in the system and the atmospheric pressure.

In the thin film distillation apparatus 10A, the wetted parts in the flow path of the raw material mixture from the raw material container 31 to the evaporation container 37, specifically, the wetted parts on the inner surface of the raw material container 31, and (of the needle valve 32) The liquid contact parts of the raw material pipe 33 (including the liquid contact parts) are preferably made of resin. Since the liquid contact part is made of resin, it is possible to suppress elution of the metal material from the liquid contact part. Quaternary ammonium hydroxide available as a raw material must contain water. Generally, water is involved in the elution reaction of metal materials. Since the liquid contact part in the flow path of the raw material mixture from the raw material container 31 to the evaporation container 37 is made of resin, the raw material mixture in which quaternary ammonium hydroxide and water coexist comes into contact with the metal material. Since the time required for this can be shortened, it is possible to suppress a reaction in which the metal material is eluted into the liquid from the liquid-contacted part and becomes a metal impurity in the liquid. From the viewpoint of further suppressing elution of the metal material from the liquid-contacted part, it is preferable that the liquid-contacted part in the flow path from the evaporation container 37 to the residual liquid recovery container 12 is also made of resin.

As the resin constituting the liquid contact portion, a resin material having durability against aqueous alkaline solutions and water-soluble organic solvents can be preferably used. Examples of such resin materials include polytetrafluoroethylene (PTFE), perfluoroalkoxyalkanes (PFA), perfluoroethylene propene copolymers (FEP), ethylene-tetrafluoroethylene copolymers (ETFE), polyvinylidene fluoride (PVDF), ); polyolefin resins such as polyethylene (PE) and polypropylene (PP); thermoplastic resins such as acrylonitrile-butadiene-styrene copolymer synthetic resins (ABS resins), nylon, acrylic resins, acetal resins, and hard vinyl chloride. and thermosetting resins such as melamine resins, furan resins, and epoxy resins. Among them, polyethylene, polypropylene, and fluororesin are particularly preferably used because they are easy to process and elute a small amount of metal impurities.

As a small-diameter pipe that does not require much strength as a structural material, a pipe made only of resin may be used. On the other hand, in large-diameter piping and raw material container 31 that require strength, it is preferable that the structural members be made of a metal material (for example, stainless steel, etc.) and that the liquid contact parts be covered with the resin material. The resin coating on the liquid-contacting part only needs to have a thickness that does not peel off, and preferably has a thickness of about 0.5 to 5 mm, for example.

Although glass is also known as a material that is not easily attacked by chemicals, a raw material mixture containing water and a highly basic substance such as quaternary ammonium hydroxide may gradually degrade even if it is made of glass. Since there is a possibility of corrosion, it is preferable to use resin rather than glass as the material constituting the liquid contact part.

When the resin material has a porous structure, metal impurities may be eluted from inside the resin, so the resin material is preferably a non-porous resin material. The content of metal impurities in the resin material constituting the liquid contact part is preferably 1 mass ppm or less, more preferably 0.1 mass ppm or less, based on the total amount of resin, for each of Na, Ca, Al, and Fe. . Such high purity resins are commercially available.

The reason why Na, Ca, Al, and Fe are mentioned here as metal impurities in the resin is, firstly, that these four types of metal impurities are typical impurities that mix in the resin; If the content of each of these in the resin is 0.1 mass ppm or less, generally the content of other metal impurities in the resin is also 0.1 mass ppm or less in most cases, and In addition, it is difficult to fully understand the content of all kinds of metal impurities, and it is rare for manufacturers to provide sufficient data on commercially available resins. Strictly speaking, the content of each of the above-mentioned Na, Mg, Al, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn in the resin is preferably 1 mass ppm or less. , more preferably 0.1 mass ppm or less.

FIG. 2 is a cross-sectional view schematically explaining details of the evaporation container 37 in the apparatus 10A. In FIG. 2, elements that already appear in FIG. 1 are given the same reference numerals as those in FIG. 1, and their explanations will be omitted. The apparatus 10A includes an evaporation container 37 and a first flow path (raw material piping 33) that introduces the raw material mixture from the upper part of the evaporation container 37 into the inside of the evaporation container 37. The raw material mixture introduced into the evaporation container 37 from the first channel (raw material piping 33) becomes a liquid film and flows down along the inner wall surface of the evaporation container 37. The device 10A further includes a heating surface 24 disposed on the inner wall surface that heats the liquid film flowing down along the inner wall surface, and a heating surface 24 disposed inside the evaporation container 37 that cools and liquefies the vapor generated from the liquid film. a condenser (internal condenser) 22; a second flow path for recovering the distillate liquefied by the condenser 22 from the evaporation container 37 to the distillate recovery container 13; A third flow path is provided for collecting the residual liquid flowing down from the evaporation container 37 into the residual liquid recovery container 12. The device 10A also includes a wiper (roller wiper) 21 that is arranged inside the evaporation container 37 and rotates along the inner wall surface of the evaporation container 37. The raw material mixture introduced into the evaporation container 37 from the first channel (piping 33) is applied to the inner wall surface by the rotating wiper 21 to form a liquid film.

The heating surface 24 is heated by a circulating heating medium 25. The flow rate when introducing the raw material mixture 23 into the evaporation container 37 can be adjusted using the needle valve 32 or a flow rate regulator (not shown). A liquid film is formed on the inner wall of the evaporation container 37 by the roller wiper 21, heat exchange is performed on the heating surface 24 arranged on the inner wall surface of the evaporation container 37, and water is evaporated. Usually, at the same time, a portion of the organic solvent also evaporates depending on the vapor pressure of the organic solvent. The evaporated water and organic solvent are condensed into a distillate in a condenser (internal condenser) 22 arranged near the center of the evaporation container 37 and separated from the liquid film. The condenser 22 is cooled by a circulating refrigerant 26.

The inner wall of the evaporation vessel 37 is generally made of a metal material with high corrosion resistance such as stainless steel from the comprehensive viewpoint of material properties such as heat resistance, abrasion resistance, corrosion resistance, thermal conductivity, and strength. is preferred. From the viewpoint of further suppressing the elution of metal impurities, it is conceivable to configure the inner wall of the evaporation container 37 with a resin member or a resin-coated metal member; In the case of a thin film, the efficiency of heat exchange between the liquid film and the heating medium 25 on the heating surface 24 decreases, so it becomes necessary to control the temperature of the heating surface 24 to a higher temperature. There is a possibility that thermal decomposition of quaternary ammonium hydroxide will proceed during distillation. Further, since the roller wiper 21 rotates inside the evaporation container 37, if the inner wall of the evaporation container 37 is also made of a resin member or a resin-coated member, when the roller wiper 21 comes into contact with the inner wall of the evaporation container 37, the evaporation container There is a possibility that the resin may peel off from the inner wall of the container 37 and resin pieces may be mixed into the recovered residual liquid.

Even if the inner wall of the evaporation container 37 is made of a metal material, the content of metal impurities in the resulting composition (residual liquid) does not deteriorate significantly. The reasons for this are not completely understood, but there are three possible reasons: (1) The residence time of the liquid film on the inner wall of the evaporation vessel is from several seconds to several minutes, which is a short time for metal impurities to be eluted. (2) Water is required for the reaction in which metal materials are eluted into alkaline liquid, but in thin film distillation, most of the water is removed from the liquid film in a short time, so the conditions for metal impurities to be eluted are not met. (3) The composition obtained by the production method of the present invention usually has a higher viscosity than the water-soluble organic solvent in the composition. Further, the raw material mixture has a relatively high viscosity depending on the viscosity of the water-soluble organic solvent and the concentration of quaternary ammonium hydroxide, but the viscosity further increases as water is distilled off. That is, when the raw material mixture passes through the heating surface 24 of the evaporation container 37, most of the water is lost in a short time at the interface between the heating surface 24 and the liquid film, and the viscosity of the liquid increases, causing the inside of the liquid film to It is thought that this makes it difficult for water to come into contact with the heating surface 24, and as a result, elution of metal impurities is suppressed.

As the roller wiper 21, one made of resin can be used, but it is preferable that a reinforcing member such as glass fiber is not blended into the resin material constituting the roller wiper 21. Since the roller wiper 21 continues to be in contact with the raw material mixture and the liquid film during thin film distillation, if the resin constituting the roller wiper 21 contains glass fibers, metal impurities such as Al and Ca in the glass fibers will be removed. It may be eluted into the liquid. Furthermore, if glass fibers are included in the resin constituting the roller wiper 21, when the roller wiper 21 comes into contact with the inner wall surface of the evaporation container 37, glass fiber fragments and fine particles generated from the inner wall surface may form a residue. There is a risk of contamination with the liquid.

Preferred examples of the resin material constituting the roller wiper 21 include polyacetal (POM), polyamide (PA), polycarbonate (PC), modified polyphenylene ether (m-PPE), polybutylene terephthalate (PBT), and ultra-high molecular weight polyethylene ( Heat-resistant general-purpose engineering plastics such as UHPE) and syndiotactic polystyrene (SPS); and super engineering plastics such as polyetheretherketone (PEEK), polyimide (PI), polyetherimide (PEI), and fluororesins. Examples include resins with relatively high strength. Among them, PEEK, PI, fluororesin, etc. can be preferably used from the viewpoint of heat resistance, strength, purity, etc.

The distillate condensed by the condenser 22 is guided to the distillate recovery container 13 and collected through a second flow path including a gear pump (liquid pump) 11 (on the distillate side). Further, uncondensed steam is captured and recovered by the cold trap 14. The residual liquid that has flowed down from the heating surface 24 after the water has been distilled off is guided to the residual liquid recovery container 12 through a third channel equipped with a gear pump (liquid feeding pump) 10 (on the residual liquid side) and is collected.

In the thin film distillation apparatus 10A (FIG. 1), for the purpose of checking the flow of the liquid after distillation, a glass pipe 8 for checking the flow rate of the residual liquid (hereinafter referred to as "glass piping") is connected to the third flow path for recovering the residual liquid. There is a glass pipe 9 (hereinafter sometimes referred to as "glass pipe 9") for checking the flow rate on the distillate side in the second channel for recovering the distillate. , respectively. However, glass pipes 8 and 9 are not necessarily required. Rather, since the glass pipes 8 and 9 are made of glass, they may become a source of contamination (a source of elution of metal impurities). From the viewpoint of further reducing the content of metal impurities in the composition (residual liquid) to be produced, for example, instead of using the thin film distillation apparatus 10A (FIG. 1), glass can be removed from the third channel of the thin film distillation apparatus 10A. A thin film distillation apparatus 10B (FIG. 3) with piping 8 removed can be preferably used.

The thin film distillation apparatus 10A (FIG. 1) is provided in the middle of a third flow path that guides the residual liquid from the evaporation container 37 to the residual liquid recovery container 12 as an element for maintaining airtightness in the system including the inside of the evaporation container 37. (residue liquid side) gear pump (liquid sending pump) 10 and a second flow path that leads the distillate from the evaporation container 37 to the distillate recovery container 13 (distillate side) A gear pump (liquid feeding pump) 11 is provided. The gear pumps (liquid pumps) 10 and 11 are liquid pumps that push out the liquid on the residual liquid side or the distillate side toward the recovery container 12 or 13 while keeping the system airtight. The material of each part (casing, gear, etc.) used in the liquid contact parts of the liquid transfer pump that also serves as airtightness may be a metal material (for example, stainless steel, etc.) having sufficient corrosion resistance. The reason for this is the same as the reason why the inner wall of the evaporation container does not need to be coated with resin. In other words, the water content of the residual liquid that comes into contact with the wetted part of the liquid feeding pump 10 on the residual liquid side is sufficiently low, and the time that the residual liquid contacts the liquid wetted part of the liquid feeding pump 10 is sufficiently short, so that the liquid cannot be fed. Even if the wetted part of the pump 10 is made of a metal material such as stainless steel, it is considered that almost no metal impurities are leached from the wetted part of the liquid pump 10 into the residual liquid. However, from the viewpoint of further reducing the content of metal impurities in the produced composition, a liquid pump having a wetted part made of resin such as engineering plastic or super engineering plastic is used as the liquid pump 10 on the residual liquid side. It is also possible to use

Examples of the vacuum pump 15 include an oil rotary pump (rotary pump), an oil diffusion pump, a cryopump, a swinging piston vacuum pump, a mechanical booster pump, a diaphragm pump, a roots-type dry pump, a screw-type dry pump, and a scroll. Known vacuum pumps such as a type dry pump and a vane type dry pump can be mentioned. As the vacuum pump 15, one vacuum pump may be used alone, or a plurality of vacuum pumps may be used in combination.

The cold trap 14 condenses or solidifies the vapor that has not been condensed in the condenser 22 into a liquid or solid, and prevents evaporated water and organic solvent from reaching the vacuum pump 15. This serves to prevent oil or oil mist vaporized from flowing into the evaporation container 37 side and contaminating the system. As the cold trap 14, a known cold trap device can be used. The cold trap 14 can be cooled using, for example, dry ice, a coolant mixture of dry ice and an organic solvent (alcohol, acetone, hexane, etc.), liquid nitrogen, a circulating refrigerant, or the like.

In the above description, the thin film distillation apparatuses 10A (FIG. 1) and 10B (FIG. 3), which are equipped with the liquid sending pumps 10 and 11 only on the downstream side of the evaporation container 37, have been taken as examples. A liquid feeding pump may also be provided on the upstream side of the. FIG. 4 is a diagram schematically illustrating a thin film distillation apparatus 10C (hereinafter sometimes simply referred to as "apparatus 10C") according to such another embodiment. In FIG. 4, elements that have already appeared in FIGS. 1 to 3 are designated by the same reference numerals as those in FIGS. 1 to 3, and their explanations will be omitted. The thin film distillation apparatus 10C has a raw material pipe 3 instead of the raw material pipe 33 that leads the raw material mixture from the raw material container 31 to the evaporation container 37, and a raw material gear pump 4 is installed in the middle of the raw material pipe 3 and downstream of the needle valve 32. This differs from the thin film distillation apparatus 10A (FIG. 1) in that it further includes a preheater 5, and a degasser 6 in this order from the upstream side. In the apparatus 10C, the wetted parts in the flow path of the raw material mixture from the raw material container 31 to the evaporation container 37, that is, the raw material piping 3 (including the needle valve 32), the raw material gear pump 4, and the preheater (preheater) 5 and the liquid contact parts of the degasser (degasser) 6 are preferably made of a resin material. However, since configuring all the wetted parts of the raw material gear pump 4, preheater 5, and degasser 6 from resin materials generally increases the device cost, the device 10A described above As in and 10B, a thin film distillation apparatus without the raw material gear pump 4, preheater 5, and degasser 6 can be preferably employed.

In the above description, the thin film distillation apparatuses 10A (FIG. 1), 10B (FIG. 3), and 10C (FIG. 4) each having a needle valve as the valve 32 are taken as examples, but the valve 32 is not necessarily a needle valve. It is not necessary, and instead of the needle valve, other known valves such as a diaphragm valve, butterfly valve, ball valve, gate valve, etc. can be used as the valve 32.

Examples of commercially available thin-film distillation equipment that can be used in step (a) include short-stroke distillation equipment (manufactured by UIC); Wipren (registered trademark), Exeba (registered trademark) (both manufactured by Kobelco Kankyo Co., Ltd.); Control, Sebcon (registered trademark) (both manufactured by Hitachi Plant Mechanics); Viscon, Film Truder (both manufactured by Buss-SMS-Canzler GmbH, available from Kimura Kakoki); Evaliator, Examples include Hi-U Blusher, Wall Wetter (both manufactured by Kansai Kagaku Kikai Seisakusho Co., Ltd.); NRH (manufactured by Nichinan Kikai Co., Ltd.); and Everpol (registered trademark) (manufactured by Okawara Seisakusho Co., Ltd.). Since quaternary ammonium hydroxide decomposes when heated for a long time, it is preferable to use a falling film type thin film distillation apparatus from the viewpoint of increasing distillation efficiency. From the same viewpoint, a short-stroke thin film distillation apparatus can be preferably used, and a falling-film short-stroke thin film distillation apparatus can be particularly preferably used.
Note that in this specification, a falling film type thin film distillation apparatus is a device in which a thin film (liquid film) of liquid introduced into the evaporation container is formed on the heating surface inside the evaporation container (for example, by a rotary blade, etc.). Refers to a thin film distillation apparatus that performs distillation while a liquid film is allowed to flow down along the line. A short-step thin-film distillation device (short-step distillation device) is a thin-film distillation device that has been developed to improve separation performance based on the technical idea of molecular distillation. In a short-step distillation apparatus, a condenser is arranged inside a cylindrical evaporation vessel such that a cooling surface of the condenser faces a heating surface of the evaporation vessel. Distillation using a short-step distillation apparatus (short-step distillation) is often performed under a pressure of about medium vacuum (on the order of 10 ⁻¹ to 10 ² Pa).

Note that when using the above-mentioned commercially available thin film distillation apparatus, it is preferable to use an apparatus modified so that the liquid-contacting part on the upstream side of the evaporation container is made of resin.

(2.2.2 Distillation conditions)
The properties of the organic solvent solution of quaternary ammonium hydroxide obtained by thin film distillation are as follows: the temperature of the raw material mixture just before entering the evaporation container 37 (first temperature), the temperature of the heating surface 24 of the evaporation container 37 (second temperature), temperature) and the degree of vacuum of the system.

The temperature (first temperature) of the raw material mixture immediately before entering the evaporation container 37 is preferably 70°C or lower, more preferably 60°C or lower. By setting the first temperature at or below the upper limit value, it is possible to further reduce the elution of metal impurities from the evaporation container 37 when the raw material mixture with a high water content contacts the inner wall surface of the evaporation container 37. It becomes possible. Further, the first temperature is preferably 5°C or higher, more preferably 15°C or higher. When the first temperature is equal to or higher than the above lower limit, it becomes possible to suppress the formation of precipitates containing quaternary ammonium hydroxide and further improve the evaporation efficiency.

The temperature of the heating surface 24 (second temperature) is preferably higher than the first temperature, preferably 60 to 140°C, more preferably 70 to 120°C. When the second temperature is equal to or higher than the lower limit value, the evaporation efficiency can be further increased and the amount of water in the liquid film can be quickly reduced, so that the elution of metal impurities from the evaporation container 37 can be further reduced. It becomes possible. Further, by setting the second temperature to the above upper limit value or less, it becomes possible to reduce evaporation of the organic solvent and further reduce elution of metal impurities from the evaporation container 37. In this specification, the "temperature of the heating surface" of the thin film distillation apparatus means the temperature of the heat source that heats the liquid film.

The degree of vacuum of the system (the degree of vacuum inside the evaporation container 37 or from the evaporation container 37 to the front of the vacuum pump) is preferably 600 Pa or less, more preferably 550 Pa or less, even more preferably 400 Pa or less, and in one embodiment, 200 Pa or less. It can be. By setting the degree of vacuum of the system to the above upper limit value or less, the evaporation efficiency can be increased and the amount of water in the liquid film can be quickly reduced, making it possible to further reduce the elution of metal impurities from the evaporation container 37. become. The lower limit of the degree of vacuum is not particularly limited, but may be 0.1 Pa or more in one embodiment, and 1 Pa or more in another embodiment. When the degree of vacuum of the system is equal to or higher than the above lower limit value, it becomes easy to avoid clogging of the exhaust system piping by evaporated matter that condenses or solidifies in the cold trap 14. The degree of vacuum in the system can be measured using a pressure measuring device (not shown) such as a manometer or a vacuum gauge provided in the middle of the exhaust system piping connecting the evaporation container 37 and the vacuum pump 15. In one embodiment, a pressure measurement device may be provided between the cold trap 14 and the vacuum pump 15.

A preferable feed rate of the raw material mixture to the evaporation vessel 37 may vary depending on the scale of the thin film distillation apparatus. If the feed rate is too high, evaporation efficiency will decrease, and if the feed rate is too low, productivity will decrease. If the distillation conditions such as the temperature of the heating surface 24 and the degree of vacuum in the evaporation container 37 are the same, the larger the heat transfer area (area of the heating surface 24) of the thin film distillation apparatus is, the higher the feed rate can be. . For example, when using a thin film distillation apparatus with a heat transfer area of 0.1 m ² , the feed rate can be preferably 1 to 10 kg/hour. The temperature of the raw material mixture just before entering the evaporation container 37 (first temperature), the temperature of the heating surface 24 (second temperature), and the degree of vacuum of the system (inside the evaporation container 37 or from the evaporation container 37 to the front of the vacuum pump) When the degree of vacuum) is within the above range, the feed rate per unit area of the heating surface 24 can be, for example, 10 to 100 kg/hour·m ² .

Through step (a), water can be removed by evaporation from the raw material mixture to obtain a solution of quaternary ammonium hydroxide in an organic solvent.

(2.3 Step (b): Cleaning step)
In one embodiment, before step (a), the liquid contact part in the flow path of the raw material mixture from the raw material container 31 to the evaporation container 37 (for example, in the above-mentioned apparatus 10A, the inner surface of the raw material container 31 A step (hereinafter referred to as "step (b)") of cleaning the liquid-contacted parts and the liquid-contacted parts of the raw material pipe 33 (including the liquid-contacted part of the needle valve 32) with the solution containing the quaternary ammonium hydroxide. ”) is preferable. Preferred examples of the cleaning liquid used for cleaning in step (b) include solutions containing the above-mentioned quaternary ammonium hydroxide, such as an aqueous solution of quaternary ammonium hydroxide used as part of the raw material and a raw material mixture. Among these, a solution containing the same quaternary ammonium hydroxide as the quaternary ammonium hydroxide contained in the raw material mixture can be particularly preferably used as the cleaning liquid. The content of metal impurities in the solution (cleaning solution) containing quaternary ammonium hydroxide is as follows for each of Na, Mg, Al, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn. It is preferably 0.05 mass ppm or less, more preferably 0.02 mass ppm or less, still more preferably 0.01 mass ppm or less, based on the total amount of solution.

Cleaning of the liquid-contacted parts can be carried out, for example, by circulating the cleaning liquid for about 10 minutes to 2 hours through the parts (for example, made of resin) that make up the liquid-contacted parts, or by passing the cleaning liquid through the parts (for example, made of resin) that make up the liquid-contacted parts. This can be done by storing and holding the above-mentioned cleaning liquid. By performing step (b) before step (a), metal impurities in a state where they can be eluted are reduced or removed from the surface of the parts that make up the wetted parts. It becomes possible to further reduce eluted metal impurities. In one preferred embodiment, after cleaning the wetted parts with an aqueous quaternary ammonium hydroxide solution or a raw material mixture, the wetted parts are further cleaned with water containing extremely low metal impurities, such as ultrapure water or pure water. It may be washed (rinsed) for a short time. According to this form of step (b), it is possible to further reduce the amount of metal impurities eluted from the liquid contact portion in step (a). For example, if it is clear that leachable metal impurities have already been reduced or removed from the surface of the (e.g., resin) member constituting the wetted part, water in a form that does not undergo step (b) may be used. It is also possible to use a method for producing a solution of quaternary ammonium oxide in an organic solvent.

It is also possible to clean the wetted parts with an acid aqueous solution, but when the acidic aqueous solution comes into contact with the wetted parts, the anions contained in the acidic aqueous solution tend to remain on the resin surface. It takes time to remove it by cleaning with water or pure water. Therefore, it is preferable not to use an acid aqueous solution to clean the wetted parts, and use a solution containing quaternary ammonium hydroxide and/or a solution containing metal impurities such as pure water or ultrapure water to clean the wetted parts. It is preferable to use very little water.

(2.4 Properties of organic solvent solution of quaternary ammonium hydroxide)
(2.4.1 Quaternary ammonium hydroxide content)
In one embodiment, the content of quaternary ammonium hydroxide in an organic solvent solution of quaternary ammonium hydroxide (hereinafter sometimes referred to as "organic solvent solution" or simply "solution") obtained by thin film distillation. The amount may be preferably 5.0% by weight or more, more preferably 8.0% by weight or more, based on the total amount of solution. When the content of quaternary ammonium hydroxide in the solution is equal to or higher than the above lower limit, the distribution cost of the solution can be saved. The upper limit of the content is not particularly limited, but may be 72% by mass or less in one embodiment, and 55% by mass or less in another embodiment. When the content of quaternary ammonium hydroxide in the solution is below the above upper limit, the increase in viscosity of the solution is suppressed, making handling, feeding, mixing, etc. when using the solution easier. .

The concentration of quaternary ammonium hydroxide in a solution can be accurately measured using a potentiometric titration device, liquid chromatography, or the like. These measuring means may be used alone or in combination. These measuring methods can also be applied to measuring the concentration of quaternary ammonium hydroxide in the raw material mixture.

In one embodiment, the content of quaternary ammonium hydroxide in the solution may be 2.38 to 25.0% by weight based on the total amount of the solution. In one preferred embodiment, TMAH can be used as the quaternary ammonium hydroxide, and the content of TMAH in the solution can be 2.38 to 25.0% by mass based on the total amount of the solution.

(2.4.2 Moisture content)
The water content in the solution obtained by thin film distillation can be 1.0% by mass or less, preferably 0.5% by mass or less, more preferably 0.3% by mass or less based on the total amount of the composition. be able to. By setting the water content in the solution to the above upper limit, the water content in the composition produced using this solution is 1.0% by mass or less, preferably 0.5% by mass or less, more preferably Since it is easy to reduce the concentration to 0.3% by mass or less, the removal performance of the modified photoresist and photoresist ashing residue of the composition manufactured using this solution is improved, and the corrosion resistance of metal materials and inorganic substrate materials is improved. This makes it possible to reduce the The lower limit of the water content in the solution is not particularly limited, but may be, for example, 0.05% by mass or more.

The amount of water in the solution can preferably be determined by a method similar to that described in Section 1.4 above in connection with the compositions of the invention.

The ratio (water content/quaternary ammonium hydroxide content) of the water content (unit: mass %) in the solution to the quaternary ammonium hydroxide content (unit: mass %) in the solution is preferably is 0.42 or less, more preferably 0.21 or less, still more preferably 0.10 or less. When the ratio is equal to or less than the above upper limit value, it becomes possible to further reduce the corrosivity to metal materials and inorganic base materials while maintaining or improving the removal performance of the modified photoresist and the ashing residue of the photoresist. The lower limit of the ratio is not particularly limited, but may be, for example, 0.0007 or more.

(2.4.3 Impurity content)
The content of metal impurities in the solution obtained by thin film distillation is preferably 100% for each of Na, Mg, Al, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn based on the total amount of the solution. It is not more than 50 ppb by mass, more preferably not more than 50 ppb by mass, even more preferably not more than 20 ppb by mass. In this specification, the content of metal impurities in a solution means the total content of the metal elements, regardless of whether they are zero-valent metals or metal ions.

The content of chlorine impurities (Cl) in the solution is preferably 100 mass ppb or less, more preferably 80 mass ppb or less, and even more preferably 50 mass ppb or less, based on the total amount of the solution. As used herein, the content of chlorine impurities in a solution means the total content of elemental chlorine. Note that in the solution, chlorine impurities usually exist in the form of chloride ions (Cl ⁻ ).

The content of metal impurities in the solution can be measured using a microanalysis device such as an inductively coupled plasma mass spectrometer (ICP-MS). Further, the content of chlorine impurities can be measured using a microanalysis device such as ion chromatography. These methods for measuring the metal impurity and chlorine impurity contents can also be applied to measuring the metal impurity and chlorine impurity contents in the raw material mixture.

Ratio of the content of the metal impurities in the solution (unit: mass ppb) to the content of quaternary ammonium hydroxide in the solution (unit: mass %) (content of metal impurities/quaternary ammonium hydroxide content) The amount) is preferably 42 or less, more preferably 21 or less, still more preferably 10 or less for each of the above metal elements. When the ratio is equal to or less than the above upper limit value, it becomes possible to further increase the manufacturing yield of semiconductor devices while maintaining or improving the removal performance of the modified photoresist and the ashing residue of the photoresist. The lower limit of the ratio is not particularly limited, and is preferably as low as possible, but may be, for example, 0.0001 or more, taking into consideration the quantification limit of a metal impurity measuring device.

The ratio (chlorine content/quaternary ammonium hydroxide content) of the content of chlorine impurities in the solution (unit: mass ppb) to the quaternary ammonium hydroxide content (unit: mass %) in the solution is , preferably 42 or less, more preferably 34 or less, still more preferably 21 or less. When the ratio is equal to or less than the above upper limit value, it becomes possible to further increase the manufacturing yield of semiconductor devices while maintaining or improving the removal performance of the modified photoresist and the ashing residue of the photoresist. The lower limit of the ratio is not particularly limited, and is preferably as low as possible, but may be, for example, 0.001 or more, taking into consideration the quantification limit of a chlorine impurity measuring device.

(2.4.4 Usage)
A solution obtained by thin film distillation can be used, for example, as it is as a composition of the present invention. Alternatively, for example, the composition of the present invention having a desired quaternary ammonium hydroxide concentration can be obtained by diluting a solution obtained by thin film distillation with the first organic solvent, the second organic solvent, or a combination thereof. can get things.

Furthermore, by adding water to the composition of the present invention, it is also possible to produce various chemical solutions with controlled water content. That is, it is also possible to use the composition of the present invention as a raw material for producing a drug solution having a controlled water content. As explained in Section 2.1.3 above, simply diluting a commercially available quaternary ammonium hydroxide aqueous solution with an organic solvent on an industrial scale will not reduce the quaternary ammonium hydroxide concentration and the organic solvent concentration. In some cases, it may not be possible to obtain a solution having a composition within the desired range. The composition of the present invention is also useful as a raw material for obtaining a quaternary ammonium hydroxide solution having such a composition.
For example, the etching rate of an etching solution such as a silicon etching solution may be required to be controlled depending on the moisture content. In such applications, it is required to strictly control the water content in the chemical solution. By adding highly purified water such as ultrapure water to the composition of the present invention, a solution whose water content is strictly controlled can be obtained. The addition of water in such applications is performed, for example, when the water content in the solution is preferably 1.0 to 40% by mass, more preferably 2.0 to 30% by mass, even more preferably 3.0% by mass, based on the total amount of the solution. It can be carried out so that the amount is 0 to 20% by mass. The water content that the solution should have after adding water is determined, for example, by the desired etching rate. In order to adjust both the water content and the concentration of quaternary ammonium hydroxide, the organic solvent (first organic solvent, second organic solvent, or combinations thereof) may be added together with water.

<3. Manufacturing (2)>
In another embodiment, the composition of the present invention comprises the step (i) of obtaining an organic solvent solution of quaternary ammonium hydroxide by the method according to the first embodiment (hereinafter referred to as "step (i)"). ), (ii) a step of determining the concentration of quaternary ammonium hydroxide in the solution (hereinafter sometimes referred to as "step (ii)"), and (iii) a step of determining the concentration of quaternary ammonium hydroxide in the solution. A method (hereinafter referred to as "second step (iii)") that includes a step (hereinafter sometimes referred to as "step (iii)") of adjusting the concentration of quaternary ammonium hydroxide in the solution by adding an organic solvent to the solution. It can be preferably manufactured by a method according to an embodiment.

(3.1 Step (i): Solution manufacturing process)
Step (i) is a step of obtaining an organic solvent solution of quaternary ammonium hydroxide by the method according to the first embodiment, the details of which are described in 2. above. As explained in Sec.

(3.2 Step (ii): Concentration understanding step)
Step (ii) is a step of determining the concentration of quaternary ammonium hydroxide in the solution obtained in step (i). The concentration of quaternary ammonium hydroxide in the solution can be preferably measured by a method similar to the method described in Section 2.4.1 above in connection with the method according to the first embodiment. . Note that an organic solvent solution of quaternary ammonium hydroxide is produced by the method according to the first embodiment under the same conditions (composition of the raw material mixture and distillation conditions) as the conditions in which step (i) was performed. If the concentration of quaternary ammonium hydroxide in the solution has been measured in the past, the concentration of quaternary ammonium hydroxide in the solution measured in the past operation record can be obtained in step (i). may be regarded as the concentration of quaternary ammonium hydroxide in the solution.

The concentration of quaternary ammonium hydroxide in a solution can be accurately measured using a commercially available measuring device such as a potentiometric titrator or a liquid chromatograph. These measuring means may be used alone or in combination. As the sample used for measurement, a sample taken from the solution may be used as it is, or a diluted sample obtained by accurately diluting the sample taken from the solution with a solvent (for example, water, etc.) may be used.

The potentiometric titration device is a device that performs measurements using the potentiometric titration method specified in JIS K0113. Potentiometric titration devices that can perform automatic measurements are commercially available and can be preferably used. Potentiometric titration is an electrochemical method that determines the volumetric equivalence point based on the change in electrode potential between an indicator and reference electrode in response to the concentration (activity) of the component of interest in the solution being titrated. It is a measurement method.
A potentiometric titration device consists of a titration tank into which the solution to be titrated is placed, a buret for adding the standard solution to the titration tank, an indicator electrode and a reference electrode to be placed in the solution, and a potential difference to measure the potential difference between the two electrodes. It will be equipped with a meter. Measurement using a potentiometric titration device is performed, for example, as follows. The solution to be titrated is placed in a titration tank, a suitable indicator electrode and a reference electrode are inserted into it, and the potential difference between the two electrodes is measured by a potentiometer. Next, a predetermined amount of the standard solution is dropped from the buret into the titration tank, stirred thoroughly to cause the standard solution and the solution to be titrated to react, and then the potential difference between the two electrodes is measured. By repeating this operation and recording the potential difference between the two electrodes corresponding to the amount of standard solution added, a potential difference-standard solution addition amount curve (hereinafter sometimes referred to as "potentiometric titration curve") is obtained. In the obtained potentiometric titration curve, the end point of the titration can be determined by determining the amount of standard solution added that corresponds to the point where the potential difference suddenly changes. The concentration of the target component in the solution to be titrated can be calculated from the amount and concentration of the standard solution added dropwise up to the end point of the titration, the reaction molar ratio of the titration reaction, and the like. When measuring the concentration of quaternary ammonium hydroxide, an acid such as sulfuric acid or hydrochloric acid (for example, 1.0N or less) is usually used as a standard solution. When the solution contains only one type of quaternary ammonium hydroxide, the concentration of quaternary ammonium hydroxide (mol/L) in the solution can be quickly and easily measured by potentiometric titration. Furthermore, even if the solution contains two or more types of quaternary ammonium hydroxide, the total concentration (mol/L) of quaternary ammonium hydroxide in the solution can be quickly and easily measured by potentiometric titration. can.

If the mixing ratio of quaternary ammonium hydroxide in a solution containing two or more types of quaternary ammonium hydroxide is unknown, the mixture of quaternary ammonium hydroxide in the solution can be determined by using liquid chromatography. Accurately measure molar ratios. For example, prepare a standard sample with a known concentration for each quaternary ammonium hydroxide (the concentration of quaternary ammonium hydroxide (mol/L) in the standard sample can be accurately measured by potentiometric titration); A calibration curve is created by measuring each of the mixtures obtained by mixing them at different mixing ratios using liquid chromatography and plotting the ratio of peak intensities in the chromatogram against the mixing ratio; An organic solvent solution of quaternary ammonium hydroxide containing two or more types of quaternary ammonium hydroxide whose ratio is unknown is measured by liquid chromatography; using a calibration curve from the ratio of peak intensities in the chromatogram. , the mixing molar ratio of quaternary ammonium hydroxide in the solution can be determined. The total concentration (mol/L) of quaternary ammonium hydroxide in a solution can be measured by potentiometric titration as described above. The concentration of each quaternary ammonium hydroxide in a solution containing quaternary ammonium hydroxide can be accurately measured.
However, the mixing ratio of quaternary ammonium hydroxide in the raw material mixture is often known at the time of preparing the raw material mixture containing two or more types of quaternary ammonium hydroxide. Furthermore, even if the raw material mixture is subjected to thin film distillation in step (i), the quaternary ammonium hydroxide does not evaporate. Therefore, in reality, it is often not necessary to measure by liquid chromatography.

The measurement method described above can also be used for measuring the concentration of quaternary ammonium hydroxide in the composition according to the first aspect of the present invention and for measuring the concentration of quaternary ammonium hydroxide in the raw material mixture. Applicable.

(3.3 Step (iii): Dilution step)
Step (iii) is a step of adjusting the concentration of quaternary ammonium hydroxide in the solution obtained in step (i) by adding an organic solvent to the solution. That is, this is a step of diluting the solution obtained in step (i) with an organic solvent.

(3.3.1 Dilution solvent)
As the organic solvent used in step (iii) (hereinafter sometimes referred to as "dilution solvent"), an organic solvent that is miscible with the first organic solvent contained in the solution obtained in step (i) above is used. be able to. Examples of preferred diluting solvents include the water-soluble organic solvents (first organic solvents) having a plurality of hydroxy groups, which are described in Section 1.2 above in connection with the composition of the present invention. The same applies to preferred embodiments. In one embodiment, the same water-soluble organic solvent as the first organic solvent contained in the solution obtained in step (i) can be particularly preferably used as the diluting solvent.
Furthermore, as explained in Section 1.3 above in relation to the composition of the present invention, the composition of the present invention can be used in addition to a water-soluble organic solvent having a plurality of hydroxy groups (first organic solvent) as a solvent. The organic solvent may further contain an organic solvent (second organic solvent) other than the water-soluble organic solvent having a plurality of hydroxy groups. In order to obtain a composition containing such a second organic solvent, the first organic solvent and the second organic solvent may be used in combination as the diluting solvent in step (iii). Examples of the second organic solvent include the organic solvents described in Section 1.3 above, and preferred embodiments thereof are also the same as above.
In step (iii), the amount of each organic solvent constituting the dilution solvent can be determined so that the concentration of each component in the produced composition is within a desired range.

The water content in the diluting solvent is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.3% by mass or less, based on the total amount of the diluting solvent. When the water content in the diluting solvent is below the above upper limit, for example, in applications such as stripping solutions and cleaning solutions, the obtained composition improves the removal performance of modified photoresist and photoresist ashing residue, and also improves the ability to remove ashing residue from metal materials. And it becomes possible to reduce the corrosivity to inorganic base materials. The lower limit of the water content in the diluting solvent is not particularly limited, but may be, for example, 0.05% by mass or more.

The content of metal impurities in the dilution solvent is preferably 100 mass ppb or less for each of Na, Mg, Al, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn based on the total amount of the dilution solvent. , more preferably 50 mass ppb or less, still more preferably 20 mass ppb or less. In this specification, the content of metal impurities in the dilution solvent means the total content of the metal elements, regardless of whether they are zero-valent metals or metal ions.

The content of Cl (chlorine impurity) in the diluent solvent is preferably 100 mass ppb or less, more preferably 80 mass ppb or less, and still more preferably 50 mass ppb or less, based on the total amount of the diluent solvent. As used herein, the content of chlorine impurities in the dilution solvent means the total content of elemental chlorine. Note that in the diluted solvent, chlorine impurities usually exist in the form of chloride ions (Cl ⁻ ).

The content of metal impurities in the dilution solvent can be measured by a microanalyzer such as an inductively coupled plasma mass spectrometer (ICP-MS). Further, the content of chlorine impurities can be measured using a microanalysis device such as ion chromatography.

(3.3.2 Dilution conditions)
In step (iii), the amount of diluting solvent added to the solution obtained in step (i) can be such that the composition of the invention is obtained. Such an amount can be determined from the concentration of quaternary ammonium hydroxide in the composition to be produced and the concentration of quaternary ammonium hydroxide in the solution obtained in step (i).

By going through steps (i) to (iii), the processing liquid composition for semiconductor manufacturing according to the first aspect of the present invention can be preferably produced.

(3.4 Manufacture of other chemical solutions)
The method according to the second embodiment described above uses a composition modified such that the water content exceeds 1.0% by mass based on the total amount of the composition, such as the etching solution described in Section 2.4.4 above. It can also be applied to the production of (chemical solutions). In the step (iii) (dilution step) described in Section 3.3 above, by further adding an amount of water (for example, ultrapure water, etc.) as required, the water content is reduced to 1.5% based on the total amount of the composition. It is possible to produce compositions modified with greater than 0% by weight. In such a modified form of the production method, the organic solvent (dilution solvent) used in step (iii) (dilution step) has a concentration of metal impurities and chlorine impurities within the range explained in Section 3.3.1 above. As long as the water content is more than 1.0% by mass.

Hereinafter, the present invention will be explained in more detail using Examples and Comparative Examples. However, the following examples are merely examples for explaining the present invention, and the present invention is not limited to these examples.

(Measuring method)
In Examples and Comparative Examples, the concentration of quaternary ammonium hydroxide in the solution was measured by potentiometric titration using an automatic potentiometric titrator AT-610 (manufactured by Kyoto Denshi Kogyo).

The amount of water in the obtained solution was obtained by correcting the value measured by Karl Fischer titration using a calibration curve. The moisture content was measured by Karl Fischer titration using a Karl Fischer moisture meter MKA-510 (manufactured by Kyoto Denshi Kogyo). The water content is measured by gas chromatography (hereinafter sometimes simply referred to as "GC") using a Shimadzu gas chromatograph GC-2014 (column: DB-WAX (manufactured by Agilent Technologies), detector: thermal conductivity type detector).

Correction of the moisture content measured by Karl Fischer titration using a calibration curve was performed according to the following steps (1) to (6).
(1) The same organic solvent as the organic solvent in the solution to be measured (propylene glycol if the organic solvent in the solution is propylene glycol (PG), hexylene glycol if the organic solvent in the solution is hexylene glycol (HG)). The water content inside was measured by Karl Fischer titration. Subsequently, by adding a small amount of water to the organic solvent, five types of solutions (hereinafter sometimes referred to as "water/organic solvent solutions") having different water contents were prepared. The amount of water added to the organic solvent can be determined in 5 steps (0.25% by mass, 0.50% by mass, 1.0% by mass, 2.0% by mass and 5.0% by mass). When the amount of water in the five types of water/organic solvent solutions prepared was measured by Karl Fischer titration, the obtained values were in good agreement with the theoretical value calculated from the amount of water in the organic solvent and the amount of water added. It was confirmed that
(2) Each of the five types of water/organic solvent solutions prepared in (1) above was analyzed by gas chromatography (GC) to obtain a GC chart containing peaks for water and organic solvent. Taking the area of the water peak in the obtained GC chart as the vertical axis (Y), calculate the amount of water in the water/organic solvent solution (theoretical value calculated from the amount of water in the organic solvent and the amount of water added). When plotted on the horizontal axis (X), both showed a good linear correlation. By calculating a regression line using the least squares method with Y as the objective variable and X as the explanatory variable, a calibration curve (first calibration curve) giving the water content from the area of the water peak in the GC chart was obtained.
(3) As a standard solution, a concentrated aqueous solution of QAH that is the same as the quaternary ammonium hydroxide (QAH) in the solution to be measured (QAH in the solution is 25% by mass TMAH aqueous solution if TMAH, 20% by mass TEAH aqueous solution if QAH in the solution is TEAH, 10% by mass TPAH aqueous solution if QAH in the solution is TPAH, 10% by mass TBAH aqueous solution if QAH in the solution is TBAH.) in a small amount. By adding these, five types of mixed liquids were prepared. The amount of water in the organic solvent is accurately measured by Karl Fischer titration in (1) above. The QAH concentration in the QAH concentrated aqueous solution was accurately measured using a potentiometric automatic titrator (thereby, the water content in the QAH concentrated aqueous solution was also determined at the same time). The mixing mass ratio of the organic solvent and the QAH concentrated aqueous solution was selected so that the water content in the mixture was in the same five levels of 0.25 to 5.0% by mass as in (1) above.
(4) The amount of water in the standard solution was measured by GC. That is, each of the five standard solutions prepared in (3) above was analyzed by gas chromatography, and each was calculated from the area of the water peak in the GC chart using the first calibration curve obtained in (2) above. The water content in the standard solution was obtained. The measured value of water content by this GC is the theoretical value of the water content in the standard solution calculated from the water content in the organic solvent, the water content in the QAH concentrated aqueous solution, and the mixing mass ratio of the organic solvent and the QAH concentrated aqueous solution. It was confirmed that the results showed good agreement.
(5) The water content of each of the five standard solutions prepared in (3) above was measured by Karl Fischer titration. For each standard solution, the water content measured by Karl Fischer titration was plotted on the vertical axis (Y), and the water content in the standard solution measured by GC in (3) above was plotted on the horizontal axis (X). Calibration that corrects the water content measured by Karl Fischer titration to the water content measured by GC for an organic solvent solution containing QAH and water by calculating a regression line using the least squares method with Y as the objective variable and X as the explanatory variable. A curve (second calibration curve) was obtained.
(6) Measure the water content of the actual solution to be measured by Karl Fischer titration, and use the obtained measurement value with the second calibration curve obtained in (5) above to determine the water content measured by GC. Corrected to.

The content of each metal impurity in the obtained solution was measured by inductively coupled plasma mass spectrometry (ICP-MS) using ICP-MS 7500cx manufactured by Agilent Technologies. The amount of chloride ions in the obtained solution was determined by pretreating the solution using a pretreatment cartridge for removing cations, and then using an ion chromatography ICS-1100 manufactured by Thermo Fisher Scientific (column: Dionex (registered trademark) Ionpac). (registered trademark) AS7 anion exchange column, eluent: additive-containing NaOH aqueous solution, detector: electrical conductivity detector), and measured by ion exchange chromatography.

(Thin film distillation equipment)
As the thin film distillation apparatus, a commercially available falling film type short path thin film distillation apparatus (manufactured by UIC, KD-10, heat transfer area 0.1 m ² ) was used as it was when purchased or with modification. Using. The device configuration in each example and comparative example is as follows.

Apparatus C: As shown in FIG. 4 (thin film distillation apparatus 10C), in order from the upstream side, raw material container 31, valve 32, piping 3, raw material gear pump 4, preheater 5, degasser 6, evaporation container (roller wiper 21 and internal (including condenser 22) 37, (residue liquid side and distillate side) glass piping for flow rate confirmation 8 and 9, (residue liquid side and distillate side) gear pumps 10 and 11, residue liquid recovery container 12, distillate It includes a recovery container 13, a vacuum pump (rotary pump and Roots pump) 15, a cold trap 14, and other piping and valves that connect them.

Regarding the material of the wetted parts in device C, the roller wiper 21 is made of a composite material of PTFE and glass fiber, and the other wetted parts are made of stainless steel (SUS304, SUS316L, SUS316Ti, SUS630 or equivalent). The residual liquid collection container 12 and the distillate collection container 13 are made of PE. The area of the heating surface 24 is 0.1 m ² .

Apparatus A: As shown in FIG. 1 (thin film distillation apparatus 10A), the raw material gear pump 4, preheater 5, and degasser 6 were removed from the configuration of apparatus C, and the valve 32 was changed to a needle valve.

Regarding the materials of the liquid contact parts in device A, the raw material container 31 was made of PE, the piping 33 was made of PFA, and the needle valve 32 for flow rate adjustment was made of PTFE. Furthermore, the material of the roller wiper 21 inside the evaporation container 37 was changed from a composite material of PTFE and glass fiber to PEEK (without glass fiber).

Small samples were cut out from the PE, PFA, PTFE, and PEEK resins used in the wetted parts of device A, decomposed, and analyzed by ICP-MS to determine each of Na, Ca, Al, and Fe in each resin. As a result of measuring metal impurities, they were all 1 mass ppm or less.

Apparatus B: As shown in FIG. 3 (thin film distillation apparatus 10B), the glass pipe 8 for checking the flow rate (on the residual liquid side) was further removed from the apparatus A. Further, the piping 38 from the outlet of the evaporation container 37 to the residual liquid collection container 12 and the distillate collection container 13 were each made of PFA.

In any of the apparatuses A to C, the degree of vacuum in the system was measured by a vacuum gauge (not shown) provided between the cold trap 14 and the vacuum pump 15.

The abbreviations and sources of materials used in each Example and Comparative Example are as follows.
25% by mass TMAH aqueous solution: TMAH aqueous solution with a tetramethylammonium hydroxide (TMAH) concentration of 25% by mass (manufactured by Tokuyama)
PG: Propylene glycol (manufactured by AGC)
HG: Hexylene glycol (manufactured by Mitsui Chemicals)

In addition, a TEAH aqueous solution, a TPAH aqueous solution, and a TBAH aqueous solution (all manufactured by Wako Pure Chemical Industries, Ltd.) were each purified by an aqueous two-tank electrolysis method, and a TEAH aqueous solution with a TEAH concentration of 20% by mass (20% by mass TEAH aqueous solution ), a TPAH aqueous solution with a TPAH concentration of 10% by mass (10% by mass TPAH aqueous solution), and a TBAH aqueous solution with a TBAH concentration of 10% by mass (10% by mass TBAH aqueous solution) were prepared, respectively, and the quaternary ammonium hydroxide as a raw material was prepared. It was used as an aqueous solution. In addition, the raw material quaternary ammonium hydroxide aqueous solution and water-soluble organic solvent were stored in a room at a room temperature of 23° C., and then used to prepare the raw material mixture.

Table 1 shows the content of metal impurities in the raw material mixtures used in each Example and Comparative Example. In Table 1, "<1" means that the value was less than 1 mass ppb.

<Comparative example 1>
An organic solvent solution of quaternary ammonium hydroxide was produced by performing thin film distillation using apparatus C (thin film distillation apparatus 10C (FIG. 4)).

The piping of the apparatus was previously disassembled, cleaned, and assembled, and then cleaned by alternately passing a TMAH aqueous solution with a TMAH concentration of 25% by mass and ultrapure water twice each.

A raw material mixture prepared by mixing 4 kg of a 25% by mass TMAH aqueous solution and 20 kg of PG in a PE clean bottle was placed in a raw material container made of SUS304 (TMAH aqueous solution/PG mixing mass ratio = 1/5). Preheater temperature 70℃, temperature of the raw material mixture just before entering the distillation container 68℃, temperature of the heating surface of the evaporation container (heating medium temperature) 100℃, degree of vacuum 1900Pa, feed rate 7.0kg/hour (heating surface temperature) Thin film distillation was performed under the conditions of feed rate per unit area: 70 kg/hour·m ² ), and a PG solution (approximately 8 kg) containing TMAH was obtained in a residual liquid collection container. Table 2 shows each condition. In Table 2, the "mixing ratio" for the raw material mixture means the mixing mass ratio of the quaternary ammonium hydroxide aqueous solution and the water-soluble organic solvent (quaternary ammonium hydroxide aqueous solution/water-soluble organic solvent). Table 3 shows the TMAH concentration, water content, content of each metal impurity, and chloride ion content in the obtained solution. In Table 3, "TXAH concentration" means the quaternary ammonium hydroxide concentration, and "<1" means that the value was less than 1 mass ppb.

<Example 1>
A solution of quaternary ammonium hydroxide in an organic solvent (composition of the present invention) was produced by performing thin film distillation (step (a)) using apparatus A (thin film distillation apparatus 10A (FIG. 1)).

The piping of the apparatus was previously disassembled, cleaned, and assembled, and then cleaned by alternately passing a TMAH aqueous solution with a TMAH concentration of 25% by mass and ultrapure water twice (step (b)).

A raw material mixture prepared by mixing 4 kg of a 25% by mass TMAH aqueous solution and 16 kg of PG in a PE clean bottle was placed in a PE raw material container (TMAH aqueous solution/PG mixing mass ratio = 1/4). The temperature of the raw material mixture immediately before entering the distillation container is 23°C, the temperature of the heating surface of the evaporation container (heating medium temperature) is 100°C, the degree of vacuum is 600 Pa, the feed rate is 10.0 kg/hour (the feed rate per unit area of the heating surface) A PG solution (approximately ⁵ kg) containing TMAH was obtained in the residual liquid collection container by performing thin film distillation under the following conditions (step (a)). The conditions and results are shown in Tables 2 and 3, respectively.

<Example 2>
Using apparatus A (thin film distillation apparatus 10A (FIG. 1)), the same equipment cleaning (step (b)) as in Example 1 is performed, and then thin film distillation (step (a)) is performed to remove hydroxide. A solution of quaternary ammonium in an organic solvent (composition of the present invention) was prepared.

A raw material mixture prepared by mixing 4 kg of a 25% by mass TMAH aqueous solution and 16 kg of PG in a PE clean bottle was placed in a PE raw material container (TMAH aqueous solution/PG mixing mass ratio = 1/4). The temperature of the raw material mixture immediately before entering the distillation vessel is 23°C, the temperature of the heating surface of the evaporation vessel (heating medium temperature) is 105°C, the degree of vacuum is 500Pa, and the feed rate is 7.0 kg/hour (feed rate per unit area of the heating surface). Thin film distillation was carried out under the conditions of: 70 kg/hour·m ² ), and a PG solution (approximately 4 kg) containing TMAH was obtained in a residual liquid collection container. The conditions and results are shown in Tables 2 and 3, respectively.

<Example 3>
Using apparatus B (thin film distillation apparatus 10B (FIG. 3)), the same equipment cleaning (step (b)) as in Example 1 is performed, and then thin film distillation (step (a)) is performed to remove hydroxide. A solution of quaternary ammonium in an organic solvent (composition of the present invention) was prepared.

A raw material mixture prepared by mixing 4 kg of a 25% by mass TMAH aqueous solution and 16 kg of PG in a PE clean bottle was placed in a PE raw material container (TMAH aqueous solution/PG mixing mass ratio = 1/4). The temperature of the raw material mixture immediately before entering the distillation container is 23°C, the temperature of the heating surface of the evaporation container (heating medium temperature) is 105°C, the degree of vacuum is 500 Pa, and the feed rate is 5.0 kg/hour (feed rate per unit area of the heating surface). Thin film distillation was carried out under the conditions of: 50 kg/hour·m ² ), and a PG solution (approximately 4 kg) containing TMAH was obtained in a residual liquid collection container. The conditions and results are shown in Tables 2 and 3, respectively.

<Example 4>
Thin film distillation was performed in the same manner as in Example 3 except that the degree of vacuum was 300 Pa, to obtain a PG solution (approximately 3 kg) containing TMAH in the residual liquid collection container. The conditions and results are shown in Tables 2 and 3, respectively.

<Example 5>
Same as Example 3 except that the temperature of the heating surface (thermal medium temperature) was 80° C., the degree of vacuum was 16 Pa, and the feed rate was 2.5 kg/hour (feed rate per unit area of heating surface: 25 kg/hour m ² ). By carrying out thin film distillation, a PG solution (approximately 4 kg) containing TMAH was obtained in a residual liquid collection container. The conditions and results are shown in Tables 2 and 3, respectively.

<Example 6>
Using apparatus B (thin film distillation apparatus 10B (FIG. 3)), the same equipment cleaning as in Example 1 was performed (step (b)), and then thin film distillation (step (a)) was performed to remove hydroxide. A solution of quaternary ammonium in an organic solvent (composition of the present invention) was prepared.

A raw material mixture prepared by mixing 4 kg of a 25% by mass TMAH aqueous solution and 8 kg of PG in a PE clean bottle was placed in a PE raw material container (TMAH aqueous solution/PG mixing mass ratio = 1/2). The temperature of the raw material mixture immediately before entering the distillation container is 23°C, the temperature of the heating surface of the evaporation container (heating medium temperature) is 105°C, the degree of vacuum is 16 Pa, and the feed rate is 2.5 kg/hour (feed rate per unit area of the heating surface). Thin film distillation was carried out under the conditions of: 25 kg/hour·m ² ), and a PG solution (approximately 3 kg) containing TMAH was obtained in a residual liquid collection container. The conditions and results are shown in Tables 2 and 3, respectively.

<Example 7>
Using apparatus B (thin film distillation apparatus 10B (FIG. 3)), the same equipment cleaning (step (b)) as in Example 1 is performed, and then thin film distillation (step (a)) is performed to remove hydroxide. A solution of quaternary ammonium in an organic solvent (composition of the present invention) was prepared.

A raw material mixture prepared by mixing 4 kg of a 25% by mass TMAH aqueous solution and 16 kg of HG in a PE clean bottle was placed in a PE raw material container (TMAH aqueous solution/HG mixing mass ratio = 1/4). The temperature of the raw material mixture immediately before entering the distillation container is 23°C, the temperature of the heating surface of the evaporation container (heating medium temperature) is 105°C, the degree of vacuum is 500 Pa, and the feed rate is 7.0 kg/hour (feed rate per unit area of the heating surface). Thin film distillation was carried out under the conditions of: 70 kg/hour·m ² ), and an HG solution (approximately 4 kg) containing TMAH was obtained in a residual liquid collection container. The conditions and results are shown in Tables 2 and 3, respectively.

<Example 8>
Using apparatus B (thin film distillation apparatus 10B (FIG. 3)), apparatus cleaning was performed in the same manner as in Example 1 (step (b)). However, instead of the TMAH aqueous solution, a 20% by mass TEAH aqueous solution was used as the cleaning liquid. Thereafter, a solution of quaternary ammonium hydroxide in an organic solvent (composition of the present invention) was produced by performing thin film distillation (step (a)) according to the following procedure.

A raw material mixture prepared by mixing 4 kg of a 20% by mass TEAH aqueous solution and 16 kg of PG in a PE clean bottle was placed in a PE raw material container (TEAH aqueous solution/PG mixing mass ratio = 1/4). The temperature of the raw material mixture immediately before entering the distillation container is 23°C, the temperature of the heating surface of the evaporation container (heating medium temperature) is 105°C, the degree of vacuum is 100 Pa, and the feed rate is 5.0 kg/hour (feed rate per unit area of the heating surface). Thin film distillation was carried out under the conditions of: 50 kg/hour·m ² ), and a PG solution (approximately 4 kg) containing TEAH was obtained in a residual liquid collection container. The conditions and results are shown in Tables 2 and 3, respectively.

<Examples 9 and 10>
Thin films were prepared in the same manner as in Example 8, except that the TEAH aqueous solution used for cleaning and preparing the raw material mixture was changed to a 10% by mass TPAH aqueous solution (Example 9) or a 10% by mass TBAH aqueous solution (Example 10). Distillation was carried out, and a PG solution (approximately 4 kg) containing TPAH or a PG solution (approximately 4 kg) containing TBAH was obtained in a residual liquid collection container. The conditions and results are shown in Tables 2 and 3, respectively.

In the TMAH PG solution obtained in Comparative Example 1, the content of metal impurities Na, Ca, and Fe exceeded 100 mass ppb, and the chlorine impurity also exceeded 100 mass ppb.
In Examples 1 to 10, for various quaternary ammonium hydroxides, high-purity hydroxide containing 1.0% by mass or less of water, 100 mass ppb or less of each metal impurity, and 100 mass ppb or less of chlorine impurities was used. A quaternary ammonium organic solvent solution was obtained. Such a high-purity quaternary ammonium hydroxide organic solvent solution has not been previously available. Depending on the thin film distillation conditions, it was also possible to reduce the water content to 0.3% by mass or less, each metal impurity to 20 mass ppb or less, and the chlorine impurity to 50 mass ppb or less (Example 5-6). The quaternary ammonium hydroxide organic solvent solutions obtained in Examples 1 to 10 had a concentration and purity that allowed them to be used as they were as processing liquid compositions for semiconductor manufacturing. The quaternary ammonium hydroxide organic solvent solutions obtained in Examples 1 to 10 above were further subjected to step (iii) of the method according to the second embodiment described above (see Section 3.3 above). By doing so, it is also possible to obtain a processing liquid composition for semiconductor manufacturing.

3, 33 Raw material piping 4 Raw material gear pump 5 Preheater (preheater)
6 Degasser (degasser)
8, 9 Glass piping for flow rate confirmation 10 Liquid feed pump ((residual liquid side) gear pump)
11 Liquid feeding pump ((distillate side) gear pump)
12 Residue liquid collection container 13 Distillate collection container 14 Cold trap 15 Vacuum pump 21 Wiper (roller wiper)
22 Condenser (internal condenser)
23 Raw material mixture 24 Heating surface 25 (circulating) heating medium 26 (circulating) refrigerant 31 Raw material container 32 Valve (needle valve)
37 Evaporation container 38 Piping

Claims (6)

Quaternary ammonium hydroxide,
A processing liquid composition for semiconductor manufacturing, comprising a first organic solvent that dissolves the quaternary ammonium hydroxide,
The first organic solvent is a water-soluble organic solvent having a plurality of hydroxy groups,
The water content in the composition is 1.0% by mass or less based on the total amount of the composition,
The content of Na, Mg, Al, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn in the composition is each 100 mass ppb or less based on the total amount of the composition,
The content of Cl in the composition is 100 mass ppb or less based on the total amount of the composition,
The water content/quaternary ammonium hydroxide content in the composition is 0.0007 or more and 0.10 or less,
A processing liquid composition for semiconductor manufacturing, characterized in that: The water content in the composition is 0.5% by mass or less based on the total amount of the composition,
The content of Na, Mg, Al, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn in the composition is each 50 mass ppb or less based on the total amount of the composition,
The content of Cl in the composition is 80 mass ppb or less based on the total amount of the composition.
The processing liquid composition for semiconductor manufacturing according to claim 1. The water content in the composition is 0.3% by mass or less based on the total amount of the composition,
The content of Na, Mg, Al, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn in the composition is each 20 mass ppb or less based on the total amount of the composition,
The content of Cl in the composition is 50 mass ppb or less based on the total amount of the composition.
The processing liquid composition for semiconductor manufacturing according to claim 1 or 2. The content of the quaternary ammonium hydroxide is 5.0% by mass or more based on the total amount of the composition.
The processing liquid composition for semiconductor manufacturing according to any one of claims 1 to 3. The content of the quaternary ammonium hydroxide is 2.38 to 25.0% by mass based on the total amount of the composition,
The quaternary ammonium hydroxide is tetramethylammonium hydroxide.
The processing liquid composition for semiconductor manufacturing according to any one of claims 1 to 3. The first organic solvent is one or more alcohols selected from dihydric alcohols and trihydric alcohols having a boiling point of 150 to 300°C and consisting of carbon atoms, hydrogen atoms, and oxygen atoms.
The processing liquid composition for semiconductor manufacturing according to any one of claims 1 to 5.

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