Cleaning composition and method for producing cleaning composition

Abstract

To provide a cleaning composition capable of reducing corrosion to metal bumps formed on a wafer.SOLUTION: A cleaning composition contains an alcohol adduct of quaternary alkylammonium fluoride and an aprotic solvent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to cleaning compositions and methods for cleaning adhesive polymers using the same. The present disclosure also relates to methods for making cleaning compositions. [Background technology]

[0002] In three-dimensional packaging technology for increasing the density of semiconductors, the thickness of each semiconductor wafer is reduced, and multiple semiconductor wafers connected by through-silicon vias (TSVs) are stacked. Specifically, the surface of a device wafer on which semiconductor devices are formed (also called the backside) is polished to make it thinner, and then electrodes including TSVs are formed on the backside.

[0003] In the backside polishing process of a device wafer, a support wafer, also known as a carrier wafer, is temporarily bonded to the semiconductor device-forming surface of the device wafer using an adhesive to impart mechanical strength to the device wafer. For temporary bonding of device wafers, an adhesive containing a heat-resistant polyorganosiloxane compound as an adhesive polymer is used. After the polishing process, if necessary, metal wiring or electrode pads containing Al, Cu, Ni, Au, etc., inorganic films such as oxide films and nitride films, or resin layers containing polyimides, etc., are formed on the backside of the device wafer. The backside of the device wafer is then bonded to tape having an acrylic adhesive layer fixed by a ring frame, thereby securing the device wafer to the tape. The device wafer is then separated from the support wafer, the adhesive on the device wafer is peeled off, and any adhesive residue on the device wafer is removed by cleaning with a cleaning agent.

[0004] Electrical connection between a semiconductor wafer and another semiconductor wafer, a package substrate, etc. can be formed via metal bumps such as bump balls. When a semiconductor wafer has metal bumps, a cleaning composition is required to have low corrosiveness to the metal bumps. Patent Documents 1 and 2 propose cleaning compositions that are less corrosive to metals such as bump balls.

[0005] Patent Document 1 (JP 2021-161196 A) describes a cleaning agent composition containing a metal corrosion inhibitor made of a thiazole-based compound.

[0006] Patent Document 2 (Korean Patent Publication No. 2018-0066550) describes a cleaning composition to which a fluorine-based surfactant is added to reduce damage to bump balls.

[0007] Patent Document 3 (JP 2023-76511 A) describes a method for reducing the moisture content in a cleaning composition, in which a cleaning composition containing a quaternary alkylammonium fluoride hydrate is contacted with a desiccant selected from the group consisting of commercially available molecular sieves, silica gel, and alumina.

[0008] Patent Document 4 (JP-A-6-316551) describes a method of adding a large amount of alcohol to a hydrate of tetrabutylammonium fluoride, and then distilling off the alcohol under reduced pressure to replace the water of hydration with the alcohol, thereby obtaining an alcohol adduct of tetrabutylammonium fluoride. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent Publication No. 2021-161196 [Patent Document 2] Korean Patent Publication No. 2018-0066550 [Patent Document 3] Japanese Patent Publication No. 2023-76511 [Patent Document 4] Japanese Patent Application Publication No. 6-316551 Summary of the Invention [Problem to be solved by the invention]

[0010] Cleaning compositions used to decompose and clean residual polyorganosiloxane compounds on device wafers contain hydrated quaternary alkylammonium fluorides, such as tetrabutylammonium fluoride trihydrate (TBAF·3H2O). Increasing the concentration of fluoride ions, a reactive species, is particularly effective for increasing the etching rate of polyorganosiloxane compounds. However, using cleaning compositions containing high concentrations of quaternary alkylammonium fluorides has led to problems with corrosion of metal bumps on wafers.

[0011] Patent Documents 1 and 2 disclose cleaning compositions in which the corrosiveness is reduced by adding a corrosion inhibitor. However, the addition of a corrosion inhibitor is a measure that assumes corrosion, and it is preferable to remove substances that cause corrosion in advance.

[0012] Various factors are thought to cause corrosion of metal bumps, but one of the substances that corrodes metals is water brought into the system by hydrates of quaternary alkylammonium fluorides. Since the addition of the above-mentioned corrosion inhibitors does not contribute to reducing the amount of water in the system, it is desirable to reduce the water content in the cleaning composition by other means. Since fluoride ions are an active species necessary for cleaning compositions, it is preferable to reduce the amount of water relative to the amount of quaternary alkylammonium fluoride rather than reducing the amount of water by reducing the amount of quaternary alkylammonium fluoride used.

[0013] However, the desiccants selected from the group consisting of molecular sieves, silica gel, and alumina described in Patent Document 3 adsorb and remove not only moisture but also fluoride ions, which are active species in decomposing adhesive polymers, and therefore it is preferable to selectively remove only moisture.

[0014] The present disclosure provides cleaning compositions that are less corrosive to metal bumps on wafers. [Means for solving the problem]

[0015] Another possible method for reducing the water content in a cleaning composition is to remove the water of hydration from the quaternary alkylammonium fluoride hydrate beforehand. Patent Document 4 describes a method for removing the water of hydration from the tetrabutylammonium fluoride hydrate, in which an excess of one alcohol selected from methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, and tert-butanol is added to tetrabutylammonium fluoride trihydrate, followed by vacuum distillation of the alcohol. Patent Document 4 also describes the alcohol adduct of tetrabutylammonium fluoride obtained by this procedure, as well as its water concentration and morphology. It also describes, in particular, that the alcohol adduct obtained using tert-butanol, a tertiary alcohol, exhibits a high reaction rate in the fluorination reaction of benzyl bromide and is in a highly stable crystalline state. Therefore, the alcohol adduct obtained using tert-butanol is expected to be applicable to other reactions.

[0016] The present inventors have found that when a cleaning composition containing an alcohol adduct of a quaternary alkylammonium fluoride and an aprotic solvent is used to clean a semiconductor wafer having metal bumps, corrosion of the metal bumps on the wafer can be reduced compared to when a hydrate of a quaternary alkylammonium fluoride containing the same amount of quaternary alkylammonium fluoride is used.

[0017] That is, the present disclosure relates to the following [1] to

[20] . [1] A cleaning composition comprising an alcohol adduct of a quaternary alkylammonium fluoride and an aprotic solvent. [2] The cleaning composition according to [1], wherein the alcohol adduct of quaternary alkylammonium fluoride is an adduct of at least one alcohol selected from the group consisting of methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, neopentyl alcohol, tert-amyl alcohol, n-hexanol, and 1-adamantanol. [3] The cleaning composition according to [1] or [2], wherein the alcohol adduct of the quaternary alkylammonium fluoride is an adduct of tert-butanol. [4] The cleaning composition according to any one of [1] to [3], wherein the mass ratio of the water content to the quaternary alkyl ammonium fluoride content in the cleaning composition (water / quaternary alkyl ammonium fluoride) is 0.20 or less. [5] The quaternary alkylammonium fluoride is represented by the following formula: R 6 R 7 R 8 R 9 N + F - (In the formula, R 6 ~R 9 each independently represents an alkyl group selected from the group consisting of a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and an n-butyl group. The cleaning composition according to any one of [1] to [4], wherein the tetraalkylammonium fluoride is represented by the following formula: [6] The cleaning composition according to any one of [1] to [5], wherein the content of the quaternary alkylammonium fluoride is 0.01 to 15% by mass relative to 100% by mass of the cleaning composition. [7] The cleaning composition according to any one of [1] to [6], wherein at least one of the aprotic solvents is (A) an N,N-disubstituted amide compound. [8] The cleaning composition according to any one of [1] to [7], wherein at least one of the aprotic solvents is (B) an ether compound. [9] The cleaning composition according to any one of [1] to [8], wherein the total content of the aprotic solvents relative to 100% by mass of the cleaning composition is 65 to 99% by mass.

[10] The cleaning composition according to any one of [1] to [9], which is a cleaning composition for cleaning an adhesive polymer.

[11] The cleaning composition according to

[10] , wherein the adhesive polymer is a polyorganosiloxane compound.

[12] A method for cleaning an adhesive polymer on a substrate using the cleaning composition according to any one of [1] to

[11] .

[13] A method for producing a device wafer, comprising cleaning an adhesive polymer on a device wafer with the cleaning composition according to any one of [1] to

[11] .

[14] A method for regenerating a support wafer, comprising cleaning an adhesive polymer on the support wafer with the cleaning composition according to any one of [1] to

[11] .

[15] A method for producing a cleaning composition, comprising a mixing step of mixing an alcohol adduct of a quaternary alkylammonium fluoride and an aprotic solvent.

[16] The quaternary alkylammonium fluoride is represented by the following formula: R 6 R 7 R 8 R 9 N + F - (In the formula, R 6 ~R 9 each independently represents an alkyl group selected from the group consisting of a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and an n-butyl group.

[15] The method for producing a cleaning composition according to

[15] , wherein the tetraalkylammonium fluoride is represented by the formula:

[17]

[15] or

[16] , a method for producing the cleaning composition according to

[15] or

[16] , comprising a substitution step of substituting at least a portion of the water of hydration contained in a hydrate of a quaternary alkyl ammonium fluoride with an alcohol to obtain an alcohol adduct of the quaternary alkyl ammonium fluoride.

[18]

[17] The method for producing a cleaning composition according to

[17] , wherein the alcohol is at least one alcohol selected from the group consisting of methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, neopentyl alcohol, tert-amyl alcohol, n-hexanol, and 1-adamantanol.

[19] The method for producing a cleaning composition according to

[17] or

[18] , wherein the alcohol is tert-butanol.

[20] The method for producing a cleaning composition according to any one of

[17] to

[19] , wherein in the substitution step, a blending ratio (mass ratio) of the quaternary alkylammonium fluoride hydrate to the alcohol (alcohol / quaternary alkylammonium fluoride hydrate) is 3 to 20. [Effects of the Invention]

[0018] According to the present disclosure, a cleaning composition can be provided that is less corrosive to metal bumps on a wafer. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention will be described in more detail below, but it should be noted that the present invention is not limited to the following embodiments.

[0020] In this specification, when "~" is used to describe a numerical range, the numerical values ​​at both ends are the upper and lower limits, respectively, and are included in the numerical range. When multiple upper or lower limits are listed, numerical ranges can be created using all combinations of the upper and lower limits. Similarly, when multiple numerical ranges are listed, separate numerical ranges can be created by individually selecting and combining the upper and lower limits from those numerical ranges.

[0021] [Cleaning composition] In one embodiment, the cleaning composition contains an alcohol adduct of a quaternary alkyl ammonium fluoride and an aprotic solvent. The alcohol adduct of a quaternary alkyl ammonium fluoride brings less water into the system than a hydrate of a quaternary alkyl ammonium fluoride. Therefore, the use of the alcohol adduct of a quaternary alkyl ammonium fluoride can reduce corrosiveness to metals.

[0022] <Quaternary alkylammonium fluoride alcohol adduct> The alcohol adduct of quaternary alkylammonium fluoride releases fluoride ions that participate in the cleavage of Si-O bonds. The quaternary alkylammonium moiety allows the salt quaternary alkylammonium fluoride to dissolve in aprotic solvents. The number of alcohols added in the alcohol adduct of quaternary alkylammonium fluoride is, for example, 2 to 5. The quaternary alkylammonium fluoride may be one type or a combination of two or more types. The alcohol may be one type or a combination of two or more types.

[0023] As the alcohol constituting the alcohol adduct of quaternary alkylammonium fluoride, various compounds can be used without any particular limitation. Preferred alcohols include, for example, linear or branched alcohols having 1 to 6 carbon atoms and cyclic alcohols having 5 to 12 carbon atoms. The alcohol is preferably a monohydric alcohol. The alcohol constituting the alcohol adduct of quaternary alkylammonium fluoride is preferably a monohydric alcohol. 10 OH(R 10R represents an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or a polycyclic hydrocarbon group having 5 to 12 carbon atoms. 10 is preferably a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a 2-methyl-2-butyl group, an n-hexyl group, or a 1-adamantyl group, more preferably an isopropyl group or a tert-butyl group, and even more preferably a tert-butyl group.

[0024] In one embodiment, the alcohol adduct of quaternary alkylammonium fluoride is an adduct of at least one alcohol selected from the group consisting of methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, neopentyl alcohol, tert-amyl alcohol, n-hexanol, and 1-adamantanol. The alcohol adduct of quaternary alkylammonium fluoride is preferably an adduct of at least one alcohol selected from the group consisting of iso-propanol and tert-butanol, and more preferably an adduct of tert-butanol.

[0025] As the quaternary alkyl ammonium fluoride, various compounds can be used without particular limitation. In one embodiment, the quaternary alkyl ammonium fluoride is represented by the following formula: R 6 R 7 R 8 R 9 N + F - (In the formula, R 6 ~R 9 each independently represents an alkyl group selected from the group consisting of a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and an n-butyl group. From the viewpoint of availability, R 6 ~R 9 are preferably all the same alkyl group. Examples of such quaternary alkylammonium fluorides include tetramethylammonium fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride, and tetrabutylammonium fluoride. From the standpoints of decomposition and cleaning performance, availability, price, and the like, the quaternary alkylammonium fluoride is preferably tetrabutylammonium fluoride (TBAF).

[0026] The alcohol adduct of quaternary alkylammonium fluoride can be produced, for example, by substituting at least a portion, preferably all, of the water of hydration contained in a hydrate of quaternary alkylammonium fluoride with an alcohol.

[0027] In one embodiment, the alcohol adduct of a quaternary alkylammonium fluoride is a compound represented by the formula: R 6 R 7 R 8 R 9 N + F - ·(R 10 OH) y ,(H2O) z (In the formula, R 6 ~R 9 each independently represents an alkyl group selected from the group consisting of a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and an n-butyl group; R 10 represents an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or a polycyclic hydrocarbon group having 5 to 12 carbon atoms, y represents a number from 2 to 4, and z represents a number from 0 to 2. R 6 ~R 9 Preferred embodiments of R are the same as those described for the quaternary alkylammonium fluorides. 10Preferred embodiments of are the same as those described for alcohols. y is preferably 3 to 4. z is preferably 0 to 1, preferably 0. In one embodiment, the alcohol adduct of quaternary alkylammonium fluoride does not contain water of hydration.

[0028] In one embodiment, the content of the quaternary alkylammonium fluoride in the cleaning composition is 0.01 to 15% by mass. Here, the "content of the quaternary alkylammonium fluoride" refers to the mass of the quaternary alkylammonium fluoride alone, excluding the mass of the alcohol and hydration water added to the quaternary alkylammonium fluoride. The content of the quaternary alkylammonium fluoride in the cleaning composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1% by mass or more. The content of the quaternary alkylammonium fluoride in the cleaning composition is preferably 15% by mass or less, more preferably 13% by mass or less, even more preferably 12% by mass or less, even more preferably 10% by mass or less, and particularly preferably 8% by mass or less. By setting the content of the quaternary alkylammonium fluoride to 0.01% by mass or more, adhesive polymers can be effectively decomposed and cleaned. By setting the content to 15% by mass or less, corrosion of metal portions included in the device formation surface of a device wafer can be further suppressed.

[0029] In one embodiment, the content of the alcohol adduct of quaternary alkylammonium fluoride in the cleaning composition is preferably 0.02% by mass or more, more preferably 0.2% by mass or more, and even more preferably 2% by mass or more. The content of the alcohol adduct of quaternary alkylammonium fluoride in the cleaning composition is preferably 40% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less, even more preferably 25% by mass or less, and particularly preferably 20% by mass or less. By setting the content of the alcohol adduct of quaternary alkylammonium fluoride to 0.02% by mass or more, adhesive polymers can be effectively decomposed and cleaned. By setting the content to 40% by mass or less, corrosion of metal portions included in the device formation surface of a device wafer can be further suppressed.

[0030] When prevention or inhibition of corrosion of metal parts or reduction of costs associated with the use of quaternary alkylammonium fluoride is particularly required, the content of quaternary alkylammonium fluoride in the cleaning composition may be 4% by mass or less, or 3% by mass or less.When a higher etching rate is required, the content of quaternary alkylammonium fluoride in the cleaning composition may be 5% by mass or more, 6% by mass or more, or 7% by mass or more.

[0031] In one embodiment, the mass ratio of the water content to the quaternary alkylammonium fluoride content in the cleaning composition (water / quaternary alkylammonium fluoride) is 0.20 or less. The mass ratio (water / quaternary alkylammonium fluoride) is preferably 0.15 or less, more preferably 0.10 or less. The lower limit of the mass ratio (water / quaternary alkylammonium fluoride) is not particularly limited, but may be, for example, 0.01 or 0.02. By setting the mass ratio (water / quaternary alkylammonium fluoride) to 0.20 or less, the etching rate can be increased and corrosiveness to metal bumps can be further reduced.

[0032] In the present disclosure, the water content in a cleaning composition is a value measured by the Karl Fischer method (CF method), where the temperature and relative humidity of the measurement atmosphere are 22°C and less than 1% RH, respectively.

[0033] In this disclosure, the content of quaternary alkylammonium fluoride in a cleaning composition is a value obtained by the following method. First, 0.4 mL of sample is weighed and dissolved in 20 mL of methanol. Water is then added to make approximately 80 mL, and potentiometric titration is performed with a 0.02 M sodium tetraphenylborate solution using an automatic titrator. A fluoroborate ion electrode is used as the indicator electrode, and a silver-silver chloride electrode is used as the reference electrode. The content of quaternary alkylammonium fluoride is calculated from the measurement results.

[0034] Aprotic solvents The aprotic solvent is not particularly limited as long as it can dissolve or disperse the alcohol adduct of quaternary alkylammonium fluoride. Since the aprotic solvent does not form solvation with the fluoride ion of the quaternary alkylammonium fluoride via hydrogen bonding, it can enhance the reactivity of the fluoride ion. Examples of aprotic solvents include N,N-disubstituted amide compounds such as N-methylpyrrolidone (NMP) and N,N-dimethylformamide (DMF); ether compounds such as dipropylene glycol dimethyl ether and dibutyl ether; and organic sulfur oxides such as dimethyl sulfoxide (DMSO) and sulfolane.

[0035] The total content of the aprotic solvent and the alcohol that may be added to the quaternary alkylammonium fluoride relative to 100% by mass of the cleaning composition is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. The total content of the aprotic solvent and the alcohol relative to 100% by mass of the cleaning composition is preferably 99.99% by mass or less, more preferably 99.95% by mass or less, and even more preferably 99.90% by mass or less.

[0036] The total content of aprotic solvents relative to 100% by mass of the cleaning composition is preferably 65% ​​by mass or more, more preferably 70% by mass or more, and even more preferably 75% by mass or more, and is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less, relative to 100% by mass of the cleaning composition.

[0037] The total content of the aprotic solvent relative to the total of the aprotic solvent and the alcohol which may be added to the quaternary alkylammonium fluoride (100% by mass) is preferably 70 to 99.99% by mass, more preferably 75 to 99.95% by mass, and even more preferably 80 to 99.90% by mass.

[0038] The aprotic solvent preferably contains at least one selected from the group consisting of (A) N,N-disubstituted amide compounds and (B) ether compounds.

[0039] In one embodiment, the aprotic solvent is substantially free of or free of aprotic solvents selected from ketones and esters. For example, the cleaning composition may contain no more than 1 wt. %, no more than 0.5 wt. %, or no more than 0.1 wt. % aprotic solvents selected from ketones and esters. ((A) N,N-disubstituted amide compound)

[0040] The aprotic solvent preferably contains an N,N-disubstituted amide compound. The N,N-disubstituted amide compound is a relatively polar aprotic solvent and can uniformly dissolve or disperse the alcohol adduct of quaternary alkylammonium fluoride in the composition. In the present disclosure, the term "N,N-disubstituted amide compound" also encompasses urea compounds (carbamide compounds) in which a hydrogen atom is not directly bonded to a nitrogen atom. Various compounds can be used as the N,N-disubstituted amide compound without any particular limitation, and examples thereof include acyclic N,N-disubstituted amides such as N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylpropionamide, N,N-diethylpropionamide, and tetramethylurea, and cyclic N,N-disubstituted amides such as 2-pyrrolidone derivatives, 2-piperidone derivatives, ε-caprolactam derivatives, 1,3-dimethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, and 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (N,N'-dimethylpropyleneurea). Among these, it is preferable to use cyclic N,N-disubstituted amides. The N,N-disubstituted amide compound may be one type or a combination of two or more types.

[0041] In one embodiment, the N,N-disubstituted amide compound has the formula (1): [ka] (In formula (1), R 1 represents an alkyl group having 1 to 4 carbon atoms. The 2-pyrrolidone derivative compound represented by formula (1) is represented by the formula (1). Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a t-butyl group. Examples of the 2-pyrrolidone derivative compound represented by formula (1) include N-methylpyrrolidone, N-ethylpyrrolidone, N-propylpyrrolidone, and N-butylpyrrolidone.

[0042] N,N-disubstituted amide compounds are preferred because of their relatively high polarity, excellent dissolving ability for quaternary alkylammonium fluorides, and ease of availability. 1 is preferably a 2-pyrrolidone derivative compound in which R is a methyl group or an ethyl group, 1 is an ethyl group, that is, a 2-pyrrolidone derivative compound, i.e., N-ethylpyrrolidone.

[0043] The content of the N,N-disubstituted amide compound is preferably 20 to 100% by mass, more preferably 30 to 90% by mass, even more preferably 35 to 85% by mass, and particularly preferably 40 to 80% by mass, when the aprotic solvent is taken as 100% by mass.

[0044] ((B) Ether Compounds) The aprotic solvent preferably contains an ether compound, and more preferably contains an ether compound and an N,N-disubstituted amide compound. By combining an ether compound with an N,N-disubstituted amide compound, a mixed solvent system exhibiting high affinity for the adhesive surface can be formed. A composition using such a mixed solvent system can achieve a high etching rate by effectively utilizing the reactivity of the quaternary alkylammonium fluoride. As the ether compound, various compounds can be used without particular limitation as long as they are aprotic solvents. The ether compound may be one type or a combination of two or more types. The ether compound preferably does not contain an ester structure or an amide structure.

[0045] In one embodiment, at least one of the ether compounds has the formula (2): R 2 O(C n H 2n O) x R 3 (2) (In formula (2), R 2 and R 3each independently represents an alkyl group selected from the group consisting of a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a t-butyl group, n is 2 or 3, and x is an integer of 1 to 4. It is a dialkyl ether of glycol represented by the formula:

[0046] Examples of dialkyl ethers of glycols represented by formula (2) include ethylene glycol dimethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, tripropylene glycol di-n-butyl ether, tetraethylene glycol dimethyl ether, tetrapropylene glycol dimethyl ether, etc. From the viewpoints of decomposition and cleaning performance, availability, cost, etc., the dialkyl ether of glycols represented by formula (2) is preferably diethylene glycol dimethyl ether or dipropylene glycol dimethyl ether, and more preferably dipropylene glycol dimethyl ether because a high etching rate can be obtained over a wide range of compositions.

[0047] The content of the glycol dialkyl ether represented by formula (2) is preferably 10 to 80 mass%, more preferably 15 to 70 mass%, and even more preferably 20 to 60 mass%, relative to 100 mass% of the aprotic solvent. In another embodiment, the content of the glycol dialkyl ether represented by formula (2) is preferably 0 to 60 mass%, more preferably 3 to 50 mass%, and even more preferably 5 to 40 mass%, relative to 100 mass% of the aprotic solvent.

[0048] In one embodiment, at least one of the ether compounds has the formula (3): R 4 OR 5 (3) (In the formula, R 4 and R 5each independently represents an alkyl group having 4 to 8 carbon atoms. It is a dialkyl ether represented by the formula:

[0049] The ether compound may contain a dialkyl ether of a glycol represented by formula (2) and a dialkyl ether represented by formula (3). By using a combination of two or more ether compounds with different polarities in this way, it is possible to effectively increase the affinity for various adhesive surfaces and obtain a composition with a wide range of applications.

[0050] Examples of the dialkyl ether represented by formula (3) include dibutyl ether, dipentyl ether, dihexyl ether, diheptyl ether, dioctyl ether, butylhexyl ether, butyloctyl ether, etc. From the viewpoints of decomposition and cleaning performance, availability, price, etc., the dialkyl ether represented by formula (3) is preferably dibutyl ether.

[0051] The content of the dialkyl ether represented by formula (3) is preferably 0 to 50 mass%, more preferably 1 to 35 mass%, and even more preferably 2 to 30 mass%, relative to 100 mass% of the aprotic solvent. A higher etching rate can be achieved by setting the content of the dialkyl ether represented by formula (3) to 0 mass% or more and 50 mass% or less. In another embodiment, the content of the dialkyl ether represented by formula (3) is preferably 30 to 70 mass%, more preferably 35 to 65 mass%, and even more preferably 40 to 60 mass%, relative to 100 mass% of the aprotic solvent.

[0052] In one embodiment, the flash point of the ether compound is 21°C or higher. By using an ether compound with a flash point of 21°C or higher, i.e., one that does not fall under the category of Hazardous Materials, Class 4, Category 1, Petroleum, requirements for equipment, work environment, etc., during the production and use of the composition can be reduced compared to the use of tetrahydrofuran (THF, flash point -17°C, Hazardous Materials, Class 4, Category 1, Petroleum), etc. For example, the flash points of diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, and dibutyl ether are 51°C, 60°C, and 25°C, respectively. The flash point is measured by the tag-closed container method (JIS K 2265-1:2007).

[0053] (Composition ratio of N,N-disubstituted amide compound and ether compound) In one embodiment, the content of the N,N-disubstituted amide compound is 10 to 90% by mass, and the content of the ether compound is 90 to 10% by mass, relative to 100% by mass of the aprotic solvent. The content of the N,N-disubstituted amide compound is preferably 15 to 85% by mass, and the content of the ether compound is preferably 85 to 15% by mass, relative to 100% by mass of the aprotic solvent. It is more preferable that the content of the N,N-disubstituted amide compound is 25 to 65% by mass, and the content of the ether compound is 75 to 35% by mass. By setting the contents of the N,N-disubstituted amide compound and the ether compound within the above ranges, the alcohol adduct of quaternary alkylammonium fluoride can be uniformly dissolved or dispersed in the composition, and a high etching rate can be achieved for various adhesive surfaces.

[0054] In one embodiment, when the aprotic solvent is taken as 100% by mass, the content of the N,N-disubstituted amide compound is 20 to 90% by mass, the content of the dialkyl ether of the glycol represented by formula (2) is 0 to 65% by mass, and the content of the dialkyl ether represented by formula (3) is 0 to 50% by mass. Preferably, the content of the N,N-disubstituted amide compound is 25 to 80% by mass, the content of the dialkyl ether of the glycol represented by formula (2) is 10 to 60% by mass, and the content of the dialkyl ether represented by formula (3) is 0 to 45% by mass.

[0055] <Additives and other ingredients> The cleaning composition may contain, as optional components, additives such as antioxidants, surfactants, preservatives, and antifoaming agents, as well as protic solvents other than alcohols, to the extent that the effects of the present invention are not significantly impaired.

[0056] In one embodiment, the cleaning composition is substantially free of, or free from, protic solvents other than alcohol. For example, the content of protic solvents other than alcohol in the composition can be 5% by weight or less, 3% by weight or less, or 1% by weight or less. The cleaning composition preferably is substantially free of, or free from, protic solvents other than alcohol derived from alcohol adducts of quaternary alkylammonium fluoride. For example, the content of protic solvents other than alcohol derived from alcohol adducts in the composition can be 5% by weight or less, 3% by weight or less, or 1% by weight or less.

[0057] In one embodiment, the cleaning composition is substantially free of or free of water, for example, the water content of the composition can be 3% or less, 2% or less, or 1% or less by weight.

[0058] [Method of manufacturing the cleaning composition] The method for producing the cleaning composition is not particularly limited. In one embodiment, the method for producing the cleaning composition includes a mixing step of mixing an alcohol adduct of a quaternary alkyl ammonium fluoride and an aprotic solvent. The cleaning composition can be prepared, for example, by mixing an alcohol adduct of a quaternary alkyl ammonium fluoride, an aprotic solvent, and other optional components.

[0059] The cleaning composition is preferably prepared by mixing an alcohol adduct of quaternary alkyl ammonium fluoride, an aprotic solvent, and other optional components under an inert gas atmosphere. For example, in a glove box filled with inert gas, the alcohol adduct of quaternary alkyl ammonium fluoride, an aprotic solvent, and other optional components are stirred and mixed using a stirrer or the like to dissolve the alcohol adduct of quaternary alkyl ammonium fluoride in the solvent. The inert gas is preferably argon gas or nitrogen gas, more preferably nitrogen gas.

[0060] In one embodiment, the method for producing a cleaning composition includes a substitution step in which at least a portion, preferably all, of the water of hydration contained in a quaternary alkylammonium fluoride hydrate is substituted with an alcohol to obtain an alcohol adduct of the quaternary alkylammonium fluoride. A method for substituting the water of hydration contained in a quaternary alkylammonium fluoride hydrate with an alcohol includes, for example, dissolving the quaternary alkylammonium fluoride hydrate in alcohol, optionally with heating, and then removing the alcohol and water under reduced pressure. This operation replaces the water hydrated in the quaternary alkylammonium fluoride with the alcohol, producing an alcohol adduct of the quaternary alkylammonium fluoride. The number of added alcohols can vary depending on the conditions for removing the alcohol. Generally, the number of added alcohols decreases under conditions that facilitate the evaporation of alcohol.

[0061] The quaternary alkylammonium fluoride hydrate used as the raw material is the same as the quaternary alkylammonium fluoride described above for the alcohol adduct of quaternary alkylammonium fluoride. Examples of the quaternary alkylammonium fluoride hydrate include the trihydrate, tetrahydrate, and pentahydrate.

[0062] The alcohol used as the raw material is the same as the alcohol described above for the alcohol adduct of quaternary alkylammonium fluoride.

[0063] In the substitution step, the blending ratio (mass ratio) of the quaternary alkylammonium fluoride hydrate to the alcohol (alcohol / quaternary alkylammonium fluoride hydrate) is preferably 3-20, and more preferably 5-20.

[0064] The temperature when removing the alcohol and water under reduced pressure may be appropriately set depending on the type of alcohol, pressure conditions, etc.

[0065] [Method of using the cleaning composition] The composition of the present disclosure can be used as a cleaning composition for adhesive polymers contained in various adhesives. The adhesive polymer is not particularly limited as long as it can be cleaned using the cleaning composition of the present disclosure. In addition to the adhesive polymer, the adhesive may contain optional components such as a curing agent, a curing accelerator, a crosslinking agent, a surfactant, a leveling agent, and a filler.

[0066] In one embodiment, the adhesive polymer contains Si-O bonds. The adhesive polymer is degraded or loses its crosslinked structure by cleavage of the Si-O bonds by the fluoride ions of the quaternary alkylammonium fluoride, making it soluble in a solvent and thus removable from the surface of a device wafer or the like.

[0067] The adhesive polymer containing Si-O bonds is preferably a polyorganosiloxane compound. Because polyorganosiloxane compounds contain numerous siloxane (Si-O-Si) bonds, they can be effectively decomposed and cleaned using a cleaning composition. Examples of polyorganosiloxane compounds include silicone resins such as silicone elastomers, silicone gels, and MQ resins, as well as their modified forms, such as epoxy-, acrylic-, methacrylic-, amino-, and mercapto-modified forms. The polyorganosiloxane compound may also be a silicone-modified polymer, such as a silicone-modified polyurethane or a silicone-modified acrylic resin.

[0068] In one embodiment, the adhesive polymer is an addition-curable silicone elastomer, silicone gel, or silicone resin. These addition-curable silicones contain an ethylenically unsaturated polyorganosiloxane, such as a vinyl-terminated polydimethylsiloxane or a vinyl-terminated MQ resin, and a polyorganohydrogensiloxane, such as a polymethylhydrogensiloxane, as a crosslinker, and are cured using a hydrosilylation catalyst, such as a platinum catalyst.

[0069] In another embodiment, the adhesive polymer comprises an aralkyl-, epoxy-, or phenyl-containing polydiorganosiloxane, particularly an aralkyl-, epoxy-, or phenyl-containing polydimethylsiloxane. An adhesive comprising such an adhesive polymer may be used for temporary bonding in combination with an adhesive comprising the addition-curable silicone.

[0070] [Method for cleaning adhesive polymers] The adhesive polymer on the substrate can be cleaned by various conventionally known methods using a cleaning composition. Examples of the cleaning method for the adhesive polymer include a method of ejecting the cleaning composition onto the substrate so as to come into contact with the adhesive polymer while rotating the substrate at a predetermined speed using a spin coater or the like (also called spin etching), a method of spraying the cleaning composition onto the adhesive polymer on the substrate (also called spraying), and a method of immersing the substrate having the adhesive polymer in a container containing the cleaning composition (also called dipping).

[0071] The substrate may be, for example, a silicon wafer.

[0072] The washing may be carried out in an air atmosphere or an inert gas atmosphere, preferably an inert gas atmosphere, preferably argon gas or nitrogen gas, more preferably nitrogen gas.

[0073] The cleaning temperature may vary depending on the type and amount of adhesive polymer attached to the substrate, and is generally 7°C to 35°C, preferably 15°C to 30°C. The cleaning time may vary depending on the type and amount of adhesive polymer attached to the substrate, and is generally 5 seconds to 10 hours, and preferably 10 seconds to 2 hours. Ultrasonic waves may be applied to the cleaning composition bath or the substrate during cleaning.

[0074] After cleaning, the substrate may be rinsed with alcohol such as isopropyl alcohol (IPA), ion-exchanged water (DIW), or the like, and the substrate may be dried by spraying with nitrogen gas, air, or the like, or by heating under normal pressure or reduced pressure.

[0075] [Device wafer manufacturing method] In one embodiment, a method for manufacturing a device wafer includes cleaning an adhesive polymer on the device wafer with a cleaning composition containing an alcohol adduct of a quaternary alkylammonium fluoride and an aprotic solvent. After cleaning, the device wafer may be optionally rinsed or dried.

[0076] The method for manufacturing a device wafer may further include the following steps: forming semiconductor devices on a substrate such as a silicon wafer to obtain a device wafer, placing the semiconductor device-forming surface of the device wafer opposite a support wafer and temporarily bonding the device wafer and the support wafer together with an adhesive containing an adhesive polymer, thinning the device wafer by polishing the surface of the device wafer opposite the device-forming surface, i.e., the backside, and separating the support wafer from the device wafer. The formation of the semiconductor devices, temporary bonding of the device wafer and the support wafer, polishing the backside of the device wafer, and separating the device wafer from the support wafer can be performed by conventionally known methods without any particular limitation.

[0077] [Support wafer regeneration method] In one embodiment, a method for regenerating a support wafer includes cleaning the adhesive polymer on the support wafer with a cleaning composition containing an alcohol adduct of a quaternary alkylammonium fluoride and an aprotic solvent. After cleaning, the support wafer may be optionally rinsed or dried.

[0078] Examples of the support wafer include a glass wafer and a silicon wafer. [Example]

[0079] [Example 1] <Preparation of cleaning composition> The tert-butanol adduct of tetrabutylammonium fluoride trihydrate (TBAF·3H2O) was prepared by dissolving TBAF in tert-butanol and removing the tert-butanol and water as follows.

[0080] (Dissolution of TBAF·3H2O in alcohol) A 100 mL borosilicate glass eggplant-shaped flask was placed in a simple glove box. Nitrogen gas was introduced into the glove box to create a nitrogen atmosphere. The temperature and relative humidity inside the glove box were measured using a digital thermo-hygrometer CHE-TP1 (Sanwa Supply Co., Ltd.), and were found to be 24 °C and less than 1% RH, respectively. 6.962 g of TBAF·3H2O (98%; 5.653 g of TBAF) were added to the eggplant-shaped flask, followed by 24.540 g of tert-butanol (Kanto Chemical Co., Ltd., special grade, 99%, water concentration: 249 ppm by mass) pre-melted in a hot bath at approximately 35 °C and a magnetic stirrer tip. The eggplant-shaped flask was sealed with a glass ball stopper and stirred at 400 rpm for 30 minutes at room temperature (24 °C) to obtain a white suspension. Furthermore, the contents of the eggplant-shaped flask were stirred and mixed for 10 minutes while immersed in an oil bath at 75°C, thereby dissolving all of the white crystals contained in the suspension.

[0081] (Removal of alcohol and water using an evaporator) Next, while the solution in which the white crystals had completely dissolved was kept warm in an oil bath at 75°C, the pressure was reduced to 320 hPa using an evaporator to remove tert-butanol and water. Ten minutes after the pressure was reduced, white crystals precipitated by recrystallization. Removal of tert-butanol and water was continued for a further 220 minutes at this temperature and pressure. The content thus obtained was weighed in a glove box under a nitrogen gas atmosphere, weighing 11.262 g.

[0082] (vacuum drying) Furthermore, to remove the remaining tert-butanol and water, a three-way cock was attached to the eggplant-shaped flask, which was then connected to a vacuum pump and dried under reduced pressure at room temperature (24°C) and 40 hPa for 2 hours and 30 minutes, yielding 11.143 g of white crystals.

[0083] (Adding solvent and dissolving) The eggplant-shaped flask containing the resulting white crystals was placed in a simple glove box purged with nitrogen gas, and 22.670 g of N-ethyl-2-pyrrolidone (NEP), 8.426 g of dipropylene glycol dimethyl ether (DPGDME), and 9.610 g of dibutyl ether (DBE) were added in this order. The eggplant-shaped flask was sealed with a glass ball stopper and stirred at 600 rpm with a magnetic stirrer under a nitrogen gas atmosphere at room temperature for 90 minutes to completely dissolve the white crystals. The water concentration of the resulting cleaning composition was measured using the Karl Fischer method (CF method) and found to be 0.55% by mass. The total mass of the cleaning composition was 51.849 g, and the mass ratio of the water content to the tetrabutylammonium fluoride content in the cleaning composition was calculated to be (0.55 / 100 × 51.849) / (6.962 × 0.98 × 261 / 315) = 0.0504. The content of the aprotic solvent, the content of tetrabutylammonium fluoride, and the content of the alcohol adduct of tetrabutylammonium fluoride were calculated to be 78.5% by mass, 10.9% by mass, and 21.5% by mass, respectively, relative to 100% by mass of the cleaning composition.

[0084] The water concentration of the cleaning composition was measured with a Karl Fischer moisture meter (MKC-710, Kyoto Electronics Industry Co., Ltd.) placed in a simple glove box while flowing instrument-dedicated dry air to sufficiently reduce the humidity in the glove box. When the temperature and relative humidity at this time were measured with the above digital thermometer and hygrometer, they were 22°C and less than 1%RH, respectively.

[0085] <Immersion Test of Sn-Cu Bump Wafer> In a simple glove box under a nitrogen gas atmosphere, 15 mL of the above-described cleaning composition was collected in a 50-mL glass sample bottle. Next, a wafer with Sn-Cu bumps having a tin plating on the surface of copper was divided into test pieces of 1.5 cm × 1.5 cm and immersed in this cleaning composition for 10 minutes. After immersion for 10 minutes, the test pieces were taken out with tweezers, immersed in isopropyl alcohol (IPA), and rinsed by thoroughly pouring IPA using a wash bottle. The surface of the test pieces after rinsing was sufficiently dried by blowing nitrogen gas. When the metal bump surface of the test pieces subjected to such an immersion test was observed by SEM, it was confirmed that the surface shape was the same as before immersion. No surface traces were found such as those seen when the bump surface was corroded by the cleaning composition.

[0086] [Comparative Example 1] <Preparation of Cleaning Composition> In a glove box filled with nitrogen gas, 6.964 g of tetrabutylammonium fluoride trihydrate (TBAF·3H2O) (98%; 5.655 g of TBAF), 22.687 g of N-ethyl-2-pyrrolidone (NEP), 8.431 g of dipropylene glycol dimethyl ether (DPGDME), and 9.613 g of dibutyl ether (DBE) were put into a 125 mL polyethylene container and mixed to dissolve TBAF·3H2O. When the water concentration of the obtained cleaning composition was measured by the Karl Fischer method (CF method) in the same manner as in Example 1, it was 2.49% by mass. The total mass of the cleaning composition was 47.695 g, and the content ratio of water to the content of tetrabutylammonium fluoride in the cleaning composition was calculated as (2.49 / 100×47.695) / (6.964×0.98×261 / 315)=0.2100.

[0087] <Immersion test of Sn-Cu bump wafer> The same immersion test as in the example was conducted. When the surface of the metal bumps of the test piece on which the immersion test was conducted was observed by SEM, traces presumed to be due to corrosion were confirmed on the bump surface.

[0088] Thus, even when the amounts of TBAF·3H2O used as starting materials and the added solvents were the same, a cleaning composition with a low mass ratio of water content to TBAF content could be prepared by passing through the formation step of the alcohol adduct and the removal step of alcohol and water as in Example 1. It was confirmed that such a cleaning composition with a low water ratio had lower corrosivity to metal bumps than the cleaning composition in which TBAF·3H2O was dissolved in a solvent.

Claims

1. A cleaning composition comprising an alcohol adduct of a quaternary alkylammonium fluoride and an aprotic solvent.

2. 2. The cleaning composition of claim 1, wherein the alcohol adduct of a quaternary alkylammonium fluoride is an adduct of at least one alcohol selected from the group consisting of methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, neopentyl alcohol, tert-amyl alcohol, n-hexanol, and 1-adamantanol.

3. 2. The cleaning composition of claim 1, wherein the alcohol adduct of a quaternary alkylammonium fluoride is an adduct of tert-butanol.

4. 2. The cleaning composition according to claim 1, wherein the mass ratio of the water content to the quaternary alkyl ammonium fluoride content in the cleaning composition (water / quaternary alkyl ammonium fluoride) is 0.20 or less.

5. The quaternary alkylammonium fluoride is represented by the following formula: R ６ R ７ R ８ R ９ N ＋ F － (In the formula, R ６ ~R ９ each independently represents an alkyl group selected from the group consisting of a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and an n-butyl group. The cleaning composition according to any one of claims 1 to 4, wherein the tetraalkylammonium fluoride is represented by the formula:

6. The cleaning composition according to any one of claims 1 to 4, wherein the content of the quaternary alkylammonium fluoride is 0.01 to 15 mass% relative to 100 mass% of the cleaning composition.

7. The cleaning composition according to any one of claims 1 to 4, wherein at least one of the aprotic solvents is (A) an N,N-disubstituted amide compound.

8. The cleaning composition according to any one of claims 1 to 4, wherein at least one of the aprotic solvents is (B) an ether compound.

9. The cleaning composition according to any one of claims 1 to 4, wherein the total content of the aprotic solvents is 65 to 99 mass% relative to 100 mass% of the cleaning composition.

10. The cleaning composition according to any one of claims 1 to 4, which is a cleaning composition for cleaning adhesive polymers.

11. The cleaning composition of claim 10, wherein the adhesive polymer is a polyorganosiloxane compound.

12. A method for cleaning adhesive polymers on a substrate using the cleaning composition according to any one of claims 1 to 4.

13. A method for producing a device wafer, comprising cleaning an adhesive polymer on the device wafer with the cleaning composition according to any one of claims 1 to 4.

14. A method for regenerating a support wafer, comprising cleaning an adhesive polymer on the support wafer with the cleaning composition according to any one of claims 1 to 4.

15. A method for producing a cleaning composition, comprising a mixing step of mixing an alcohol adduct of a quaternary alkylammonium fluoride and an aprotic solvent.

16. The quaternary alkylammonium fluoride is represented by the following formula: R ６ R ７ R ８ R ９ N ＋ F － (In the formula, R ６ ~R ９ each independently represents an alkyl group selected from the group consisting of a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and an n-butyl group. The method for producing the cleaning composition according to claim 15, wherein the tetraalkylammonium fluoride is represented by the formula:

17. 16. The method for producing the cleaning composition according to claim 15, comprising a substitution step of substituting at least a portion of the water of hydration contained in a hydrate of a quaternary alkyl ammonium fluoride with an alcohol to obtain an alcohol adduct of the quaternary alkyl ammonium fluoride.

18. 18. The method for producing a cleaning composition according to claim 17, wherein the alcohol is at least one alcohol selected from the group consisting of methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, neopentyl alcohol, tert-amyl alcohol, n-hexanol, and 1-adamantanol.

19. The method of making a cleaning composition according to claim 17, wherein the alcohol is tert-butanol.

20. The method for producing a cleaning composition according to any one of claims 17 to 19, wherein in the substitution step, a blending ratio (mass ratio) of the quaternary alkylammonium fluoride hydrate to the alcohol (alcohol / quaternary alkylammonium fluoride hydrate) is 3 to 20.

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