Method for cleaning adhesive polymer

Abstract

To provide a cleaning method capable of cleaning an adhesive polymer on a substrate with the improved etching rate.SOLUTION: A cleaning method for cleaning an adhesive polymer on a substrate using a cleaning composition containing a quaternary alkylammonium fluoride or a hydrate thereof and an organic solvent is carried out in an environment in which the relative humidity is controlled to 45% RH or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a cleaning method for adhesive polymers, and in particular to a cleaning method for adhesive polymers for decomposing and cleaning an adhesive that contains an adhesive polymer used for temporarily bonding a device wafer and a support wafer (carrier wafer) remaining on a device wafer in a semiconductor wafer thinning process. [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 (backside) of a device wafer on which semiconductor devices are formed is polished to make it thinner, and then electrodes including TSVs are formed on the backside.

[0003] In the polishing process of the back surface of the device wafer, a support wafer also called a carrier wafer is temporarily bonded to the semiconductor device forming surface of the device wafer using an adhesive in order to impart mechanical strength to the device wafer. For example, a glass wafer or a silicon wafer is used as the support wafer. After the polishing process, metal wiring or electrode pads containing Al, Cu, Ni, Au, etc., inorganic films such as oxide films and nitride films, or resin layers containing polyimide, etc. are formed on the polished surface (back surface) of the device wafer as necessary. Thereafter, the back surface of the device wafer is bonded to a tape having an acrylic adhesive layer fixed by a ring frame, so that the device wafer is fixed to the tape. Thereafter, the device wafer is separated from the support wafer (debonding), the adhesive on the device wafer is peeled off, and the adhesive residue on the device wafer is washed away using a cleaning agent.

[0004] For the temporary bonding of device wafers, adhesives containing polyorganosiloxane compounds with good heat resistance as adhesive polymers are used. In particular, when the adhesive is a crosslinked polyorganosiloxane compound, the cleaning agent is required to have two functions: cleavage of Si-O bonds and dissolution of decomposition products by a solvent. Examples of such cleaning agents include those in which a fluorine-based compound such as tetrabutylammonium fluoride (TBAF) is dissolved in a polar aprotic solvent. The fluoride ions of TBAF are involved in cleavage of Si-O bonds via the formation of Si-F bonds, and therefore can impart etching performance to the cleaning agent. Polar aprotic solvents can dissolve TBAF and do not form solvations with fluoride ions via hydrogen bonds, and therefore can increase the reactivity of fluoride ions.

[0005] In Non-Patent Document 1 (Advanced Materials, 11, 6, 492 (1999)), a 1.0 M TBAF solution using aprotic THF as a solvent is used to decompose and dissolve and remove polydimethylsiloxane (PDMS).

[0006] In Non-Patent Document 2 (Advanced Materials, 13, 8, 570 (2001)), aprotic solvents such as NMP, DMF and DMSO are used as solvents for TBAF, in addition to THF.

[0007] Non-Patent Document 3 (Macromolecular Chemistry and Physics, 217, 284-291 (2016)) describes the results of investigating the etching rate of PDMS using TBAF / organic solvent for each solvent, and for THF and DMF, which have high etching rates, it also describes a comparison of the etching rates of TBAF solutions using mixed solvents with different THF / DMF ratios. [Prior art documents] [Non-patent literature]

[0008] [Non-Patent Document 1] Advanced Materials, 11, 6, 492 (1999) [Non-Patent Document 2] Advanced Materials, 13, 8, 570 (2001) [Non-Patent Document 3] Macromolecular Chemistry and Physics, 217, 284-291 (2016) Summary of the Invention [Problem to be solved by the invention]

[0009] The present disclosure provides cleaning methods capable of cleaning adhesive polymers on substrates with improved etch rates. [Means for solving the problem]

[0010] The present inventors have found that an improved etching rate can be obtained by performing cleaning in an environment in which the relative humidity is controlled to 45% RH or less.

[0011] That is, the present disclosure relates to the following [1] to

[16] . [1] A cleaning method for cleaning an adhesive polymer on a substrate using a cleaning composition containing a quaternary alkylammonium fluoride or a hydrate thereof and an organic solvent, the cleaning being carried out in an environment in which the relative humidity is controlled to 45% RH or less. [2] The cleaning method according to [1], wherein the cleaning is carried out in an environment in which the relative humidity is controlled to 35% RH or less. [3] The cleaning method according to [1], wherein the cleaning is carried out in a casing having a relative humidity of 45% RH or less. [4] The cleaning method described in [3], further comprising a step of introducing dry air into the casing. [5] The cleaning method described in [3], further comprising a step of introducing an inert gas into the casing. [6] The cleaning method according to any one of [1] to [5], wherein the organic solvent is an aprotic solvent. [7] The cleaning method according to [6], wherein at least one of the aprotic solvents is (A) an N,N-disubstituted amide compound. [8] The (A) 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 cleaning method according to [7], wherein the 2-pyrrolidone derivative compound is represented by the following formula: [9] The cleaning method according to any one of [6] to [8], wherein at least one of the aprotic solvents is an ether compound (B).

[10] At least one of the (B) ether compounds is represented by the formula (2): R 2 O(C n H 2n O) x R 3 (2) (In formula (2), R 2 and R 3 each 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 from 1 to 4. The cleaning method according to [9], wherein the alkyl ether is a dialkyl ether of a glycol represented by the formula:

[11] At least one of the (B) ether compounds is represented by the formula (3): R 4 OR 5 (3) (In the formula, R 4 and R 5 each independently represents an alkyl group having 4 to 8 carbon atoms. The cleaning method according to [9] or

[10] , wherein the dialkyl ether is represented by the formula:

[12] The quaternary alkyl ammonium fluoride is R 6 R 7 R 8 R 9 N + F - R is a tetraalkylammonium fluoride represented by the formula 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.

[13] The cleaning method according to any one of [1] to

[12] , wherein the content of the quaternary alkylammonium fluoride is 0.01 to 10 mass % relative to 100 mass % of the cleaning composition.

[14] The cleaning method according to any one of [1] to

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

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

[14] .

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

[14] . Effect of the Invention

[0012] The cleaning method of the present disclosure allows for the cleaning of adhesive polymers on substrates with improved etch rates.

[0013] The above description should not be considered as a disclosure of all embodiments of the present invention and all advantages associated with the present invention. [Brief description of the drawings]

[0014] [Figure 1]1 is a graph in which the change in thickness of the adhesive layer is plotted against the cleaning time, based on the evaluation results of Examples 1 and 2 and Comparative Example 1. [Diagram 2] 1 is a graph in which the change in thickness of the adhesive layer is plotted against the cleaning time, based on the evaluation results of Example 3 and Comparative Example 2. [Diagram 3] 1 is a graph in which the change in thickness of the adhesive layer is plotted against the cleaning time, based on the evaluation results of Example 4 and Comparative Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention will be described in further detail below. Note that the present invention is not limited to the following embodiments.

[0016] In this specification, when "to" 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.

[0017] <Cleaning method for cleaning adhesive polymer on substrate> In one embodiment, the cleaning method for cleaning an adhesive polymer on a substrate is a method of cleaning in an environment in which the relative humidity is controlled to 45% RH or less using a cleaning composition containing a quaternary alkyl ammonium fluoride or its hydrate and an organic solvent. In the present disclosure, the relative humidity of the environment in which cleaning is performed is a representative value of the relative humidity of the environment in which cleaning is performed, specifically, the relative humidity at a location that is not affected by splashes of the cleaning composition in the environment in which cleaning is performed, and is not near the gas outlet when gas is introduced into the environment (for example, a location that is not near the gas outlet and is not directly splashed with splashes of the cleaning composition). When cleaning is performed inside a casing, the relative humidity of the environment in which cleaning is performed is a representative value of the relative humidity in the casing, specifically, the relative humidity at a location that is not affected by splashes of the cleaning composition in the casing, and is not near the inlet of replacement gas such as dry air and inert gas that is circulated to replace the inside of the casing. Usually, the change in the relative humidity of the environment during cleaning is small. Therefore, the relative humidity near the surface of the substrate before the start of cleaning can also be considered as the relative humidity of the environment in which cleaning is performed. For example, in the case of cleaning by spin etching, it is the relative humidity in the vicinity of the surface of the substrate placed in a spin coater or the like (within a range of 5 to 10 cm) before the start of ejection of the cleaning composition. In the case of cleaning by spraying, it is the relative humidity in the vicinity of the surface of the substrate placed in a spray device or the like before the start of spraying of the cleaning composition. In the case of cleaning by dipping, it is the relative humidity in the vicinity of the surface of the substrate placed in an immersion tank before filling with the cleaning composition.

[0018] The adhesive polymer can be washed by various conventionally known methods. Examples of the method for washing the adhesive polymer include a method (spin etch) in which a cleaning composition is discharged onto a 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, a method (spray) in which a cleaning composition is sprayed onto the adhesive polymer on the substrate, and a method (dipping) in which a substrate having an adhesive polymer is immersed in a container containing a cleaning composition.

[0019] The cleaning may be performed in an air atmosphere or an inert gas atmosphere, so long as the relative humidity is controlled to 45% RH or less. The relative humidity is preferably 35% RH or less, more preferably 30% RH or less, even more preferably 20% RH or less, and particularly preferably 10% RH or less. The lower limit of the relative humidity is not particularly limited, and may be, for example, 0.1% RH or 1.0% RH. The relative humidity range needs to be maintained from the start of cleaning to the end of cleaning.

[0020] As a method for controlling the relative humidity of the cleaning environment, for example, cleaning is performed in a casing with a predetermined relative humidity range. Specifically, as a method for performing cleaning in an environment in which the relative humidity is controlled to 45% RH or less, for example, cleaning is performed in a casing with a relative humidity of 45% RH or less. The relative humidity in the casing is preferably 35% RH or less, more preferably 30% RH or less, even more preferably 20% RH or less, and particularly preferably 10% RH or less. When cleaning is performed by dipping, for example, a method can be used in which a container containing a cleaning composition and a substrate having an adhesive polymer is placed in a casing, and cleaning is performed while controlling the relative humidity in the casing to a predetermined range.

[0021] The cleaning method for cleaning the adhesive polymer on the substrate may include a step of introducing dry air into the casing in order to control the relative humidity in the casing to a predetermined range. An example of the dry air is dry air for instrumentation. By introducing dry air into the casing, the cost of the gas used can be reduced compared to the case of introducing an inert gas. Cleaning may be performed after replacing the inside of the casing with dry air, or cleaning may be performed while flowing dry air into the casing.

[0022] The cleaning method for cleaning the adhesive polymer on the substrate may include a step of introducing an inert gas into the casing in order to control the relative humidity in the casing to a predetermined range. Specific examples of the inert gas include at least one selected from nitrogen gas and argon gas, and nitrogen gas is preferred. By introducing an inert gas into the casing, the contact between the cleaning composition and air is suppressed, preventing the incorporation of moisture into the cleaning composition, and also reducing the oxygen concentration to suppress oxidation of the cleaning composition. When an inert gas is introduced into the casing, the inert gas concentration in the casing is preferably 95% by volume or more, more preferably 97% by volume or more, and even more preferably 99% by volume or more. Cleaning may be performed after replacing the inside of the casing with an inert gas, or cleaning may be performed while flowing an inert gas into the casing.

[0023] The cleaning time may vary depending on the type and amount of the adhesive polymer on the substrate, and is generally 5 seconds to 10 hours, preferably 10 seconds to 2 hours. During cleaning, ultrasonic waves may be applied to the bath of the cleaning composition or to the substrate.

[0024] The temperature of the environment in which the washing is performed is preferably 7 to 35° C., more preferably 8 to 30° C., and even more preferably 10 to 25° C. The temperature of the environment in which the washing is performed is the temperature of the gas phase of the environment in which the washing operation is performed (for example, the upper space of the casing when washing is performed inside a casing). It is preferable that the temperature of the environment in which the washing is performed is room temperature, since there is no need to control the temperature.

[0025] The temperature of the cleaning composition is preferably 7 to 35° C., more preferably 8 to 30° C., and even more preferably 10 to 25° C. The temperature of the cleaning composition may be the same as or different from the temperature of the environment in which cleaning is performed. It is preferable that the temperature of the cleaning composition is room temperature, since there is no need to control the temperature.

[0026] After cleaning, the substrate may be rinsed with an alcohol such as isopropyl alcohol (IPA), deionized 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.

[0027] [Cleaning composition] The cleaning composition of one embodiment contains a quaternary alkyl ammonium fluoride or a hydrate thereof, and an organic solvent.

[0028] <Quaternary alkyl ammonium fluoride or its hydrate> Quaternary alkylammonium fluoride or its hydrate releases fluoride ions that are involved in the cleavage of Si-O bonds. The quaternary alkylammonium moiety allows the salt quaternary alkylammonium fluoride to dissolve in an organic solvent. As the quaternary alkylammonium fluoride, various compounds can be used without particular limitation. Hydrates of quaternary alkylammonium fluoride include, for example, trihydrate, tetrahydrate, and pentahydrate. The quaternary alkylammonium fluoride may be one type or a combination of two or more types. The non-hydrate and hydrate of quaternary alkylammonium fluoride can be used in any ratio.

[0029] In one embodiment, the quaternary alkyl ammonium fluoride is R 6 R 7 R 8 R 9 N + F - R is a tetraalkylammonium fluoride represented by the formula 6 ~R 9 are each independently 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. 6 ~R 9are preferably all the same alkyl group. Examples of such quaternary alkyl ammonium fluoride include tetramethylammonium fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride, and tetrabutylammonium fluoride. From the viewpoints of decomposition and cleaning performance, availability, and price, the quaternary alkyl ammonium fluoride is preferably tetrabutylammonium fluoride (TBAF).

[0030] In one embodiment, the content of the quaternary alkyl ammonium fluoride in the cleaning composition is 0.01 to 10% by mass. Here, the "content of the quaternary alkyl ammonium fluoride" is a value calculated as the mass of only the quaternary alkyl ammonium fluoride excluding the mass of the hydrate of the quaternary alkyl ammonium fluoride when the composition contains a hydrate of the quaternary alkyl ammonium fluoride. The content of the quaternary alkyl ammonium fluoride in the cleaning composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more. The content of the quaternary alkyl ammonium fluoride in the cleaning composition is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 2% by mass or less, and particularly preferably 1% by mass or less. The combination of these lower limit values ​​and upper limit values ​​may be any combination. In another embodiment, the content of the quaternary alkyl ammonium fluoride in the cleaning composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more. In this embodiment, the content of the quaternary alkyl ammonium fluoride in the cleaning composition is preferably 9% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less. Any combination of these lower limit values ​​and upper limit values ​​may be used. By making the content of the quaternary alkyl ammonium fluoride 0.01% by mass or more, the adhesive polymer can be effectively decomposed and cleaned. By making it 10% by mass or less, corrosion of the metal parts included in the device formation surface of the device wafer can be prevented or suppressed.

[0031] When prevention or inhibition of corrosion of metal parts or reduction of costs associated with the use of quaternary alkyl ammonium fluoride is particularly required, the content of quaternary alkyl ammonium fluoride in the cleaning composition may be 4 mass % or less, or 3 mass % or less.When a higher etching rate is required, the content of quaternary alkyl ammonium fluoride in the cleaning composition may be 5 mass % or more, 6 mass % or more, or 7 mass % or more.

[0032] <Organic solvent> The organic solvent is not particularly limited as long as it can dissolve or disperse the quaternary alkyl ammonium fluoride or its hydrate. The organic solvent is preferably an aprotic solvent. The aprotic solvent does not form a solvation with the fluoride ion of the quaternary alkyl ammonium fluoride via hydrogen bonds, and therefore can increase the reactivity of the fluoride ion. Examples of the aprotic solvent 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.

[0033] The content of the organic solvent 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 content of the organic solvent 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. Any combination of these lower and upper limits may be used.

[0034] The content of the aprotic solvent 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 content of the aprotic solvent 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. Any combination of these lower and upper limits may be used.

[0035] The content of the aprotic solvent relative to 100% by mass of the organic solvent is preferably 95 to 100% by mass, more preferably 98 to 100% by mass, and further preferably 100% by mass.

[0036] The organic solvent preferably contains at least one aprotic solvent selected from the group consisting of (A) N,N-disubstituted amide compounds and (B) ether compounds.

[0037] In one embodiment, the organic solvent is substantially free or free of aprotic solvents selected from ketones and esters. For example, the cleaning composition may contain no more than 1% by weight, no more than 0.5% by weight, or no more than 0.1% by weight of aprotic solvents selected from ketones and esters. ((A) N,N-disubstituted amide compounds)

[0038] The organic solvent preferably contains an N,N-disubstituted amide compound as an aprotic solvent. The N,N-disubstituted amide compound is a relatively highly polar aprotic solvent, and can dissolve or disperse the quaternary alkyl ammonium fluoride and its hydrate uniformly in the composition. In the present disclosure, the "N,N-disubstituted amide compound" also includes a urea compound (carbamide compound) in which a hydrogen atom is not directly bonded to a nitrogen atom. As the N,N-disubstituted amide compound, various compounds can be used without 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.

[0039] 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.

[0040] 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 1 More preferably, it is a 2-pyrrolidone derivative compound in which is a methyl group, that is, N-methylpyrrolidone.

[0041] The content of the N,N-disubstituted amide compound is preferably 20 to 100 mass%, more preferably 30 to 90 mass%, further preferably 35 to 85 mass%, and particularly preferably 40 to 80 mass%, when the organic solvent is taken as 100 mass%.

[0042] ((B) Ether Compounds) The organic solvent preferably contains an ether compound as an aprotic solvent, 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 showing high affinity to the adhesive surface can be formed. A composition using such a mixed solvent system can achieve a high etching rate by effectively utilizing the reaction activity of quaternary alkyl ammonium 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 is preferably one that does not contain an ester structure or an amide structure.

[0043] 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 from 1 to 4. It is a dialkyl ether of a glycol represented by the formula:

[0044] Examples of the dialkyl ether of glycol 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. The dialkyl ether of glycol represented by formula (2) is preferably diethylene glycol dimethyl ether or dipropylene glycol dimethyl ether from the viewpoints of decomposition and cleaning performance, availability, price, etc., and more preferably dipropylene glycol dimethyl ether because a high etching rate can be obtained over a wide range of compositions.

[0045] The content of the dialkyl ether of the glycol represented by formula (2) is preferably 10 to 80 mass%, more preferably 15 to 70 mass%, and even more preferably 20 to 60 mass%, based on 100 mass% of the organic solvent. In another embodiment, the content of the dialkyl ether of the glycol represented by formula (2) is preferably 0 to 60 mass%, more preferably 3 to 50 mass%, and even more preferably 5 to 40 mass%, based on 100 mass% of the organic solvent.

[0046] In one embodiment, at least one of the ether compounds has 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:

[0047] 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 two or more types of ether compounds having different polarities in combination, it is possible to effectively increase the affinity for various adhesive surfaces and obtain a composition with a wide range of applications.

[0048] 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. The dialkyl ether represented by formula (3) is preferably dibutyl ether from the viewpoints of decomposition and cleaning performance, availability, price, etc.

[0049] 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%, when the organic solvent is taken as 100 mass%. By setting the content of the dialkyl ether represented by formula (3) to 0 mass% or more and 50 mass% or less, a higher etching rate can be obtained. 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%, when the organic solvent is taken as 100 mass%.

[0050] In one embodiment, the flash point of the ether compound is 21° C. or higher. By using an ether compound having a flash point of 21° C. or higher, i.e., not falling under the category of Class 4 Hazardous Substances, Class 1 Petroleum, the requirements for equipment, working environment, etc. in the production and use of the composition can be reduced compared to the case of using tetrahydrofuran (THF, flash point -17° C., Class 4 Hazardous Substances, Class 1 Petroleum) or the like. 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 method (JIS K 2265-1:2007).

[0051] (Composition ratio of N,N-disubstituted amide compound and ether compound) In one embodiment, when the organic solvent is taken as 100% by mass, 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. When the organic solvent is taken as 100% by mass, the content of the N,N-disubstituted amide compound is preferably 15 to 85% by mass, the content of the ether compound is preferably 85 to 15% by mass, and the content of the N,N-disubstituted amide compound is more preferably 25 to 65% by mass, and the content of the ether compound is more preferably 75 to 35% by mass. In another embodiment, when the organic solvent is taken as 100% by mass, the content of the N,N-disubstituted amide compound is preferably 40 to 80% by mass, and the content of the ether compound is preferably 60 to 20% by mass. By setting the content of the N,N-disubstituted amide compound and the ether compound in the above range, the quaternary alkyl ammonium fluoride and its hydrate can be uniformly dissolved or dispersed in the composition, and a high etching rate can be obtained for various adhesive surfaces.

[0052] In one embodiment, when the organic 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 10 to 80% by mass, and the content of the dialkyl ether represented by formula (3) is 0 to 30% 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 20 to 60% by mass, and the content of the dialkyl ether represented by formula (3) is 0 to 30% by mass. In another embodiment, when the organic 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 70% by mass, and the content of the dialkyl ether represented by formula (3) is 0 to 30% by mass. Preferably, the content of the N,N-disubstituted amide compound is 30 to 85 mass%, the content of the dialkyl ether of the glycol represented by formula (2) is 3 to 50 mass%, and the content of the dialkyl ether represented by formula (3) is 0 to 30 mass%. In still another embodiment, when the organic solvent is taken as 100 mass%, the content of the N,N-disubstituted amide compound is 20 to 80 mass%, the content of the dialkyl ether of the glycol represented by formula (2) is 10 to 50 mass%, and the content of the dialkyl ether represented by formula (3) is 30 to 60 mass%.

[0053] <Additives and other ingredients> The cleaning composition may contain additives such as antioxidants, surfactants, preservatives, and antifoaming agents as optional components, provided that the effects of the present invention are not significantly impaired.

[0054] In one embodiment, the cleaning composition is substantially free of protic solvent or free of protic solvent.For example, the content of protic solvent in the composition can be 5% by weight or less, 3% by weight or less, or 1% by weight or less.The protic solvent that can be included in the composition can be water derived from quaternary alkyl ammonium fluoride hydrate.

[0055] [Method of manufacturing cleaning composition] The method for producing the cleaning composition is not particularly limited. For example, the cleaning composition can be prepared by mixing the quaternary alkyl ammonium fluoride or its hydrate, an organic solvent, and other optional components.

[0056] The cleaning composition is preferably prepared by mixing quaternary alkyl ammonium fluoride or its hydrate, organic solvent, and other optional components under an inert gas atmosphere.For example, in a glove box filled with inert gas, quaternary alkyl ammonium fluoride or its hydrate, organic solvent, and other optional components are stirred and mixed using a stirrer or the like to dissolve quaternary alkyl ammonium fluoride or its hydrate in the solvent.The inert gas is preferably argon gas or nitrogen gas, and more preferably nitrogen gas.

[0057] [Base material] The substrate is not particularly limited, but for example, a silicon wafer can be used.

[0058] [Adhesive polymer]

[0059] The adhesive polymer is not particularly limited as long as it can be cleaned using the cleaning composition. For example, the adhesive polymer contained in various adhesives can be mentioned. 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.

[0060] In one embodiment, the adhesive polymer contains a Si-O bond. The adhesive polymer is depolymerized or loses its crosslinked structure by cleavage of the Si-O bond by the fluoride ion of the quaternary alkyl ammonium fluoride, and becomes soluble in a solvent, so that the adhesive polymer can be removed from the surface of a device wafer or the like.

[0061] The adhesive polymer containing Si-O bonds is preferably a polyorganosiloxane compound. Since the polyorganosiloxane compound contains a large number of siloxane bonds (Si-O-Si), it can be effectively decomposed and cleaned using a cleaning composition. Examples of the polyorganosiloxane compound include silicone resins such as silicone elastomers, silicone gels, and MQ resins, as well as modified versions thereof such as epoxy modified, acrylic modified, methacrylic modified, amino modified, and mercapto modified. The polyorganosiloxane compound may be a silicone modified polymer such as a silicone modified polyurethane or a silicone modified acrylic resin.

[0062] In one embodiment, the adhesive polymer is an addition-cured silicone elastomer, silicone gel, or silicone resin that includes 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 is cured with a hydrosilylation catalyst, such as a platinum catalyst.

[0063] In another embodiment, the adhesive polymer may include at least one selected from the group consisting of methyl group-containing polyorganosiloxane, epoxy group-containing polyorganosiloxane, and phenyl group-containing polyorganosiloxane. These polyorganosiloxanes are preferably at least one selected from the group consisting of polydimethylsiloxane, epoxy group-containing polydimethylsiloxane, and phenyl group-containing polydimethylsiloxane.

[0064] The addition curable silicone may be combined with at least one member selected from the group consisting of methyl group-containing polyorganosiloxanes, epoxy group-containing polyorganosiloxanes, and phenyl group-containing polyorganosiloxanes.

[0065] [Device wafer manufacturing method] In one embodiment, a method for producing a device wafer includes cleaning an adhesive polymer on the device wafer with a cleaning composition containing a quaternary alkyl ammonium fluoride or a hydrate thereof and an organic solvent. After cleaning, the device wafer may be optionally rinsed or dried.

[0066] The method for manufacturing a device wafer may further include the following steps: forming a semiconductor device 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 via an adhesive containing an adhesive polymer, thinning the device wafer by polishing the surface (back surface) of the device wafer opposite the device-forming surface, and separating the support wafer from the device wafer. The formation of the semiconductor device, the temporary bonding of the device wafer and the support wafer, the polishing of the back surface of the device wafer, and the separation of the device wafer from the support wafer may be performed by a conventionally known method and are not particularly limited.

[0067] [Support wafer regeneration method] In one embodiment, the method for regenerating a support wafer includes cleaning the adhesive polymer on the support wafer with a cleaning composition containing a quaternary alkyl ammonium fluoride or a hydrate thereof and an organic solvent. After cleaning, the support wafer may be rinsed or dried as required. EXAMPLES

[0068] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0069] <Preparation of silicon wafer test piece having adhesive layer containing polyorganosiloxane compound> An addition-curing silicone resin was applied by spin coating onto a 12-inch (300 mm) silicon wafer (thickness 770 μm) so that the dry film thickness was 110 μm. Then, the wafer was heated on a hot plate at 140° C. for 15 minutes and at 190° C. for 10 minutes to form an adhesive layer on the silicon wafer. The silicon wafer with the adhesive layer was divided into test pieces measuring 1.0 cm x 0.5 cm, and the thickness of the center of the test piece was measured using a micrometer.

[0070] <Preparation for cleaning test> Four SUS plates (25mm x 100mm x 3mm) were attached to the bottom of a SUS square tray (outer dimensions 295mm x 230mm x 49mm) with double-sided tape to form a frame with a square bottom with a side length of 100mm and a depth of 3mm. A SUS petri dish with a diameter of 90mm and a depth of 20mm was placed in this frame. That is, the petri dish was in a state where it could move back and forth and left and right with an amplitude of 10mm within the frame. Next, the short side of the above test piece was grasped with flat tweezers with a length of 125mm and fixed with a clip, and the tip was brought into contact with the circumferential surface of the bottom of the SUS petri dish, and the surface having the adhesive layer was arranged so that it was diagonally upward. Meanwhile, the base part of the tweezers was leaned against the circumferential part on the opposite side to the test piece and left stationary. In order to confirm the movement of the test piece and the tweezers when the petri dish was shaken, 26mL of the cleaning composition was placed in the petri dish, and the petri dish was shaken back and forth and left and right at 1Hz. At this time, it was confirmed that the test piece and the tweezers did not separate from the petri dish and moved in the same manner as the petri dish. In the following examples and comparative examples, a petri dish on which the tweezers holding the test piece were leaned was used for the cleaning test in the same manner as above.

[0071] [Example 1] <Preparation of cleaning composition> A simple glove box was placed in a dissolution tank with an internal volume of 0.025 m 3A SUS container was placed in the glove box. Nitrogen gas was introduced into the glove box at a flow rate of 40 L / min to create a nitrogen gas atmosphere inside. Next, tetrabutylammonium fluoride trihydrate (TBAF·3H2O) was dissolved in the following manner. After 1,701 g of TBAF·3H2O (98%) was added to the dissolution tank, 12,611 g of N-methylpyrrolidone (NMP), 1,250 g of dipropylene glycol dimethyl ether (DPGDME), and 2,375 g of dibutyl ether (DBE) were added in this order and mixed by rotating a stirring blade with a diameter of 140 mm at 250 rpm. In this way, a cleaning composition (TBAF content: 7.7 mass%) of a mixed solvent with a mass ratio of NMP:DPGDME:DBE of 0.777:0.077:0.146 was prepared.

[0072] <Cleaning test> As described above, a SUS square tray, a petri dish, and tweezers holding a test piece were placed in a simplified glove box. The humidity was reduced by flowing sufficient dry air for instrumentation inside the glove box. The temperature and relative humidity inside the glove box were measured using a digital thermo-hygrometer CHE-TP1 manufactured by Sanwa Supply placed on a SUS square tray, and were found to be 24°C and 3.6% RH, respectively. Dry air for instrumentation was continued to flow into the glove box during the cleaning operation described below. Next, 26 mL of the cleaning composition was poured into the SUS petri dish, and the test piece was immersed in the composition. After pouring, the petri dish was shaken back and forth and left and right for a specified time (4 minutes or 8 minutes) to clean the adhesive layer on the test piece. The shaking was performed manually while watching a stopwatch so that the center of the petri dish drew a square locus with a side of 1 cm at a pace of one revolution per second. The relative humidity inside the glove box during cleaning was 3.6% RH. After washing, the test piece was removed from the petri dish and rinsed by immersing it in isopropyl alcohol (IPA), and then dried by thoroughly spraying nitrogen gas onto the test piece. The thickness of the center of the test piece was measured using a micrometer.

[0073] The etching rate (ER) of the cleaning composition was calculated by dividing the difference in thickness of the test piece before and after immersion by the immersion time in the cleaning composition (4 minutes or 8 minutes) according to the following formula. The results are shown in Table 1. Etching rate (ER) (μm / min) = [(thickness of test piece before immersion - thickness of test piece after immersion, washing and drying) (μm)] / immersion time (min)

[0074] The change in thickness of the adhesive layer before and after immersion was calculated according to the following formula. The results are shown in Table 2 and Figure 1. Change in adhesive layer thickness (μm) = (thickness of test piece after immersion, washing, and drying - thickness of test piece before immersion) (μm)

[0075] [Example 2] The same operation as in Example 1 was performed except that the relative humidity in the glove box was set to 32% RH by adjusting the amount of dry air for instrumentation by opening a part of the simplified glove box replaced with dry air for instrumentation to introduce indoor air (52% RH) into the glove box. The etching rate and the change in thickness of the adhesive layer before and after immersion were calculated in the same manner as in Example 1. The results are shown in Tables 1 and 2 and FIG. 1.

[0076] [Comparative Example 1] The same operation as in Example 1 was carried out, except that the atmosphere in which the cleaning operation was carried out was a normal indoor air atmosphere (temperature 24°C, 52% RH). The etching rate and the change in thickness of the adhesive layer before and after immersion were calculated in the same manner as in Example 1. The results are shown in Tables 1 and 2 and in FIG.

[0077] [Table 1]

[0078] [Table 2]

[0079] [Example 3] <Preparation of cleaning composition> In a glove box filled with nitrogen gas, 5.396 g of tetrabutylammonium fluoride trihydrate (TBAF·3H2O) (98%), 50.902 g of N-ethyl-pyrrolidone (NEP), 18.927 g of dipropylene glycol dimethyl ether (DPGDME), and 21.533 g of dibutyl ether (DBE) were added to a 125 mL polyethylene container and mixed to dissolve TBAF·3H2O. In this way, a cleaning composition (TBAF content: 4.53 mass%) of a mixed solvent with a mass ratio of NEP:DPGDME:DBE of 0.557:0.207:0.236 was prepared. In the glove box, the gas phase in the polyethylene container containing the prepared cleaning composition was filled with nitrogen gas, and the lid of the polyethylene container was closed. The cleaning composition was obtained by storing the mixture at room temperature (25°C) for 2 days under this nitrogen gas atmosphere.

[0080] <Cleaning test> A cleaning test was carried out in the same manner as in Example 1, except that the temperature in the glove box was 23°C, the relative humidity was 3.8%RH, the cleaning composition was used, and the shaking time of the petri dish was 4 minutes or 6 minutes. The etching rate and the change in thickness of the adhesive layer before and after immersion were calculated in the same manner as in Example 1. The results are shown in Tables 3 and 4 and in FIG. 2.

[0081] [Comparative Example 2] The same operation as in Example 3 was carried out, except that the atmosphere in which the cleaning operation was carried out was a normal indoor air atmosphere (temperature 23°C, 49% RH). The etching rate and the change in thickness of the adhesive layer before and after immersion were calculated in the same manner as in Example 3. The results are shown in Tables 3 and 4 and in FIG.

[0082] [Table 3]

[0083] [Table 4]

[0084] [Example 4] <Preparation of cleaning composition> In a glove box filled with nitrogen gas, 3.940 g of tetrabutylammonium fluoride trihydrate (TBAF·3H2O) (98%), 35.923 g of N,N-dimethylpropionamide (DMPA), 11.157 g of dipropylene glycol dimethyl ether (DPGDME), and 42.183 g of dibutyl ether (DBE) were added to a 125 mL polyethylene container and mixed to dissolve TBAF·3H2O. In this way, a cleaning composition (TBAF content: 3.43 mass%) of a mixed solvent with a mass ratio of DMPA:DPGDME:DBE of 0.402:0.125:0.473 was prepared. In the glove box, the gas phase in the polyethylene container containing the prepared cleaning composition was filled with nitrogen gas, and the lid of the polyethylene container was closed. The mixture was stored under this nitrogen gas atmosphere at room temperature (25° C.) for 2 days to obtain a cleaning composition.

[0085] <Cleaning test> A cleaning test was carried out in the same manner as in Example 1, except that the temperature in the glove box was 24°C, the relative humidity was 4.3%RH, the cleaning composition was used, and the shaking time of the petri dish was 4 minutes or 8 minutes. The etching rate and the change in thickness of the adhesive layer before and after immersion were calculated in the same manner as in Example 1. The results are shown in Tables 5 and 6 and FIG. 3.

[0086] [Comparative Example 3] The same operation as in Example 4 was carried out, except that the atmosphere in which the cleaning operation was carried out was a normal indoor air atmosphere (temperature 24°C, 49% RH). The etching rate and the change in thickness of the adhesive layer before and after immersion were calculated in the same manner as in Example 4. The results are shown in Tables 5 and 6 and in FIG.

[0087] [Table 5]

[0088] [Table 6]

Claims

1. A cleaning method for cleaning an adhesive polymer on a substrate using a cleaning composition containing a quaternary alkylammonium fluoride or a hydrate thereof and an organic solvent, the cleaning being carried out in an environment in which the relative humidity is controlled to 45% RH or less.

2. 2. The cleaning method according to claim 1, wherein the cleaning is carried out in an environment in which the relative humidity is controlled to 35% RH or less.

3. 2. The cleaning method according to claim 1, wherein the cleaning is carried out in a casing having a relative humidity of 45% RH or less.

4. The cleaning method according to claim 3, further comprising the step of introducing dry air into the casing.

5. The cleaning method according to claim 3, further comprising the step of introducing an inert gas into the casing.

6. The cleaning method according to claim 1 , wherein the organic solvent is an aprotic solvent.

7. The cleaning method according to claim 6, wherein at least one of the aprotic solvents is (A) an N,N-disubstituted amide compound.

8. The (A) N,N-disubstituted amide compound is represented by the formula (1): 【Chemistry 1】 (In formula (1), R １ represents an alkyl group having 1 to 4 carbon atoms. The cleaning method according to claim 7, wherein the 2-pyrrolidone derivative compound is represented by the formula:

9. The cleaning method according to any one of claims 6 to 8, wherein at least one of the aprotic solvents is (B) an ether compound.

10. At least one of the ether compounds (B) is represented by the formula (2): R ２ O(C ｎ H ２ｎ O) ｘ R ３ (2) (In formula (2), R ２ and R ３ each 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 from 1 to 4. The cleaning method according to claim 9, wherein the alkyl group is a dialkyl ether of a glycol represented by the formula:

11. At least one of the (B) ether compounds is represented by formula (3): R ４ OR ５ (3) (In the formula, R ４ and R ５ each independently represents an alkyl group having 4 to 8 carbon atoms. The cleaning method according to claim 9, wherein the dialkyl ether is represented by the formula:

12. The quaternary alkyl ammonium fluoride is R ６ R ７ R ８ R ９ N ＋ F － R is a tetraalkylammonium fluoride represented by the formula: ６ ~R ９ The cleaning method according to any one of claims 1 to 8, wherein 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.

13. The cleaning method according to any one of claims 1 to 8, wherein the content of the quaternary alkyl ammonium fluoride relative to 100% by mass of the cleaning composition is 0.01 to 10% by mass.

14. The cleaning method according to any one of claims 1 to 8, wherein the adhesive polymer is a polyorganosiloxane compound.

15. A method for producing a device wafer, comprising cleaning an adhesive polymer on a device wafer by the cleaning method according to any one of claims 1 to 8.

16. A method for regenerating a support wafer, comprising cleaning an adhesive polymer on the support wafer by the cleaning method according to any one of claims 1 to 8.

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