Protective film composition for dicing, wafer manufacturing method, and wafer processing method

Abstract

Provided are: a protective film composition for dicing that contains an ultraviolet absorber that includes a compound (1) represented by formula (1), a water-soluble resin, formate ions, and water, the formate ion content being 300–6000 ppm by mass; and a wafer manufacturing method and a wafer processing method utilizing same. (In the formula, X represents a hydrogen atom or –OR1, R1 represents a substituted or unsubstituted alkyl group with a carbon number in the range 1–5, n represents a number in the range 1–5, and m represents a number in the range 0–4.)

Description

Protective film composition for dicing, wafer manufacturing method, and wafer processing method

[0001] The present invention relates to a protective film composition for dicing, a wafer manufacturing method, and a wafer processing method.

[0002] Wafers formed in the semiconductor device manufacturing process are stacked layers of insulating films and functional films on the surface of a semiconductor substrate such as silicon, and are divided by grid-like dividing lines called streets, with each area divided by the streets becoming a semiconductor chip such as an IC or LSI. That is, multiple semiconductor chips are obtained by processing and cutting the wafer along these streets.

[0003] Wafer processing and cutting are performed, for example, by laser dicing. When performing laser dicing, a dicing protective film is provided on the surface of the wafer to prevent debris from adhering. As a technology related to such a dicing protective film, for example, Patent Document 1 discloses a protective film agent for laser dicing, which is characterized by comprising a solution in which a water-soluble resin and at least one water-soluble laser light absorber selected from the group consisting of water-soluble dyes, water-soluble pigments, and water-soluble ultraviolet absorbers are dissolved.

[0004] Japanese Patent Application Laid-Open No. 2006-140311

[0005] As described above, the protective film for dicing prevents the adhesion of debris generated during dicing, but there is still room for improvement in its performance.

[0006] First, some compositions for forming protective films for dicing (protective film compositions for dicing) contain absorbents that absorb the laser light used during dicing, but there is a problem in that the absorbance decreases over time as the storage period elapses. If the absorbance decreases unintentionally, it becomes impossible to cut with a laser beam with high precision along the street line, and it becomes difficult to achieve laser processing with a uniform line width.

[0007] Next, the wafer protected by the protective film for dicing is cut by laser dicing, and then the protective film for dicing is removed by cleaning. In recent years, defect control on substrates has become stricter in order to fabricate precision structures, and therefore, there is a need to further improve surface defects after cleaning the protective film. However, with conventional protective film compositions for dicing, there was a problem in that residues after substrate cleaning worsened over time.

[0008] The present invention has been made in view of the above circumstances, and has as its main object to provide a protective film composition for dicing that can suppress a decrease in absorbance over time and an increase in the number of defects over time, as well as a wafer manufacturing method and a wafer processing method using the same.

[0009] As a result of intensive research to achieve the above-mentioned object, the present inventors have discovered a protective film composition for dicing that contains an ultraviolet absorber including compound (1) having a specific structure, a water-soluble resin, formate ions, and water, and that has a formate ion content of 300 to 6000 ppm by mass, thereby completing the present invention.

[0010] That is, the present invention is as follows: <1> A protective film composition for dicing, comprising an ultraviolet absorber containing a compound (1) represented by the following general formula (1), a water-soluble resin, formate ions, and water, wherein the content of the formate ions is 300 to 6000 ppm by mass:

[0011]

[0012] (wherein X is a hydrogen atom, -OR １ Represents R １represents a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms. n represents a number from 1 to 5, and m represents a number from 0 to 4.) <2> The protective film composition for dicing according to <1>, wherein the ultraviolet absorber is at least one selected from the group consisting of ferulic acid, 2-hydroxycinnamic acid, 4-hydroxycinnamic acid, 2,3-dihydroxycinnamic acid, and 3,4-dihydroxycinnamic acid. <3> The protective film composition for dicing according to <1> or <2>, wherein the water-soluble resin is at least one resin selected from the group consisting of resin (2a) containing a structural unit represented by the following formula (2a-1) and a structural unit represented by the following formula (2a-2), and resin (2b) containing a structural unit represented by the following formula (2b):

[0013]

[0014] <4> The protective film composition for dicing according to any one of <1> to <3>, further comprising an aqueous organic solvent. <5> The protective film composition for dicing according to <4>, wherein the aqueous organic solvent is at least one selected from the group consisting of glycol-based solvents and alcohol-based solvents. <6> The protective film composition for dicing according to <4> or <5>, wherein the aqueous organic solvent comprises two or more aqueous organic solvents. <7> The protective film composition for dicing according to any one of <1> to <6>, wherein the solid content concentration is 1 to 90 mass%. <8> A method for manufacturing a wafer, comprising: a film-forming step of applying the protective film composition for dicing according to any one of <1> to <7> to a processing surface of a wafer to form a protective film; and a processing step of irradiating the processing surface with laser light through the protective film to perform processing. <9> The method for manufacturing a wafer according to <8>, wherein the wafer has a plurality of semiconductor chips formed thereon, the semiconductor chips being partitioned by lattice-shaped streets, and the processing step is a step of irradiating the streets with laser light through the protective film to form grooves. <10> The method for producing a wafer according to <8> or <9>, further comprising the step of removing the protective film by washing with water after the processing step.<11> A method for processing a wafer, further comprising the steps of: a film-forming step of applying the protective film composition for dicing according to any one of <1> to <7> to a processing surface of a wafer to form a protective film; and a processing step of irradiating the processing surface with laser light through the protective film to perform processing.

[0015] According to the present invention, it is possible to provide a protective film composition for dicing that can suppress a decrease in absorbance over time and an increase in the number of defects over time, as well as a wafer manufacturing method and a wafer processing method using the same.

[0016] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be implemented by appropriately modifying it within the scope of its gist. Furthermore, unless otherwise specified, the configurations and parameters disclosed in this specification can be arbitrarily combined. Furthermore, unless otherwise specified, the upper and lower limits of the values ​​disclosed in this specification can be arbitrarily combined.

[0017] <Protective film composition for dicing>

[0018] The protective film composition for dicing according to this embodiment contains an ultraviolet absorber including a compound (1) represented by the following general formula (1), a water-soluble resin, formate ions, and water, and has a formate ion content of 300 to 6000 ppm by mass:

[0019]

[0020] (wherein X is a hydrogen atom, -OR １ Represents R １ represents a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, n represents a number from 1 to 5, and m represents a number from 0 to 4.

[0021] By incorporating an ultraviolet absorber having a structure represented by general formula (1) and a water-soluble resin and controlling the content of formate ions, it is possible to at least suppress a decrease in absorbance over time and to suppress an increase in the number of defects over time. For example, fluctuations in absorbance result in changes in the absorption wavelength, but by controlling the content of formate ions in the protective film composition for dicing according to this embodiment, such a defect can be suppressed. Furthermore, when debris is washed away with water or the like after laser dicing, if the debris is not completely removed by washing and remains on the wafer surface, this can cause a defect such as an increase in the number of defects over time. However, the protective film composition for dicing according to this embodiment can also suppress such a defect.

[0022] Hereinafter, various components of the protective film composition for dicing according to this embodiment will be described.

[0023] (ultraviolet absorber)

[0024] Compound (1) has a structure represented by general formula (1). The hydroxy group (—OH) in general formula (1) may be present in a dissociated state in a solution composition. Compound (1) may also be incorporated as a salt thereof. The type of salt of compound (1) is not particularly limited, but may be at least one selected from the group consisting of alkali metal salts (lithium salts, sodium salts, potassium salts, etc.) and hydrates thereof, from the viewpoints of water solubility and compatibility with other components. By using compound (1) having such a structure, film peeling during laser processing can be suppressed, thereby effectively preventing debris adhesion. For example, when irradiated with laser light, thermal decomposition of the substrate progresses prior to thermal decomposition of the protective film, and the pressure of the silicon vapor, etc., which is a thermal decomposition product, forms a void between the protective film and the peripheral portion of the chip surface (near the street line) (i.e., partial peeling of the protective film occurs at the peripheral portion), which is thought to result in debris adhesion at the peripheral portion of the chip surface. In this regard, according to the present embodiment, the compound (1) is used in combination with a water-soluble resin and a specific content of formate ions, etc., so that adhesion of such debris can be effectively suppressed.

[0025] The hydroxy group (—OH) bonded to the benzene ring of compound (1) is preferably located at the para- and / or ortho-position relative to the acrylic acid group (—C═C—COOH). When there are two or more hydroxy groups, it is preferable that at least one of them is located at the para- and / or ortho-position. This structure facilitates the formation of a resonance structure or dimer that can effectively suppress the decrease in absorbance over time (however, the functions and effects of this embodiment are not limited to these).

[0026] X in the general formula (1) is a hydrogen atom or -OR １ Although it may be any of the above, it is preferably a hydrogen atom.

[0027] X in the general formula (1) is —OR １If R １ is a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms. The lower limit of the number of carbon atoms may be 2 or more. The upper limit of the number of carbon atoms may be 4 or less.

[0028] R １ When is a substituted alkyl group (an alkyl group having a substituent), examples of the substituent include a halogen atom (a chloro group, a bromo group, an iodo group, etc.), a hydroxy group, a carbonyl group, a carboxy group, a nitro group, an amino group, and a sulfo group.

[0029] R １ When X is a substituted or unsubstituted alkyl group, examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-pentyl group, an isopentyl group, and a tert-pentyl group. Among these, a methyl group is preferred. １ In the case where ３ ) are listed.

[0030] n is a number of 1 to 5, preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2.

[0031] m is a number from 0 to 4, and X is -OR. １ When m is a group, it is preferably 0 to 3, more preferably 0 to 2, and even more preferably 0 or 1. When all Xs are hydrogen atoms, it is preferable that n+m=5.

[0032] In the structure of general formula (1), X is preferably an alkoxy group (for example, a methoxy group), n is 1 or 2, m is 4 or 3, and n + m = 5. Such a structure can suppress film peeling during laser processing, and can more effectively prevent debris from adhering.

[0033] A preferred example of the type of ultraviolet absorber is at least one selected from the group consisting of ferulic acid, 2-hydroxycinnamic acid, 4-hydroxycinnamic acid, 2,3-dihydroxycinnamic acid, and 3,4-dihydroxycinnamic acid. Using such a compound can suppress film peeling during laser processing, thereby more effectively preventing debris from adhering.

[0034] The ultraviolet absorbers may be used alone or in combination of two or more.

[0035] The content of the ultraviolet absorber in the dicing protective film composition according to this embodiment is not particularly limited as long as it does not impair the object of this embodiment, but it is preferably 1 to 10 parts by mass per 100 parts by mass of the water-soluble resin in the dicing protective film composition. The lower limit of the content of the ultraviolet absorber per 100 parts by mass of the water-soluble resin in the dicing protective film composition is more preferably 1.5 parts by mass or more, and even more preferably 2 parts by mass or more. Furthermore, the upper limit of the content of the ultraviolet absorber per 100 parts by mass of the water-soluble resin in the dicing protective film composition is more preferably 8 parts by mass or less, and even more preferably 7 parts by mass or less.

[0036] (Water-soluble resin)

[0037] It contains a water-soluble resin. A protective film can be effectively formed by dissolving it in a solvent such as water or an aqueous medium, applying it, and drying it. Furthermore, after performing a predetermined process, such as laser processing including laser ablation, the protective film can be easily removed by rinsing with water.

[0038] Unless otherwise specified, the term "water-soluble" in the context of a water-soluble resin herein means that 0.5 g or more of the solute (the resin) dissolves in 100 g of water at 25°C. Water-soluble resins also include resins that have been solubilized in water by hydrolysis or treatment with a base in an aqueous medium. For example, a resin that has undergone such a reaction or treatment and is thereby capable of dissolving 0.5 g or more of the solute (the resin) in 100 g of water at 25°C also falls within the scope of the term "water-soluble resin" herein.

[0039] The dicing protective film formed on the wafer surface is usually removed from the surface by washing with water at an appropriate time after the formation of the processing groove. Therefore, from the viewpoint of the water washability of the dicing protective film, a water-soluble resin with high affinity with water is preferable. From such a viewpoint, suitable examples of the water-soluble resin preferably include at least one selected from the group consisting of vinyl resins, polyvinyl alcohol resins, and cellulose resins, and more preferably at least one selected from the group consisting of vinyl resins and polyvinyl alcohol resins.

[0040] The weight-average molecular weight of the water-soluble resin is not particularly limited, but is usually preferably 100 to 300,000. The lower limit of this weight-average molecular weight is more preferably 1,000 or more, and even more preferably 10,000 or more. The upper limit of this weight-average molecular weight is more preferably 200,000 or less, and even more preferably 150,000 or less. Unless otherwise specified, the weight-average molecular weight in this specification is the weight-average molecular weight (M ) in terms of polystyrene obtained by gel permeation chromatography (GPC) analysis. ｗ )

[0041] The type of water-soluble resin is not particularly limited, but is preferably at least one selected from the group consisting of polyvinyl alcohol-based resins, vinyl-based resins, and cellulose-based resins. Such water-soluble resins are not only highly water-soluble but also highly compatible with other components in the dicing protective film composition, making it possible to more effectively suppress changes in absorbance and defect count over time.

[0042] Specific examples of polyvinyl alcohol-based resins include polyvinyl alcohol (PVA), polyvinyl acetal (including vinyl acetate copolymers), butenediol-vinyl alcohol copolymers, polyvinyl alcohol-polyacrylic acid block copolymers, polyvinyl alcohol-polyacrylic acid ester block copolymers, etc. Among these, polyvinyl alcohol is preferred.

[0043] The vinyl resin is preferably a water-soluble homopolymer of a monomer having a vinyl group or a copolymer of a monomer having a vinyl group. Specific examples of the vinyl resin include at least one selected from the group consisting of polyvinyl alcohol resin, poly-N-vinylacetamide, polyvinylpyrrolidone (PVP), polyacrylamide, poly(N-alkylacrylamide), polyallylamine, poly(N-alkylallylamine), partially amidated polyallylamine, poly(diallylamine), allylamine-diallylamine copolymer, and polyacrylic acid.

[0044] The cellulose-based resin is preferably cellulose or a cellulose derivative, and is water-soluble. Examples of the cellulose derivative include cellulose modified with an alkyl group (e.g., a methyl group, an ethyl group, etc.) and cellulose modified with a hydroxyalkyl group (e.g., a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, etc.). Specific examples of the cellulose derivative include at least one selected from the group consisting of methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose.

[0045] The structure of the water-soluble resin is preferably at least one resin selected from the group consisting of resin (2a) containing a structural unit represented by formula (2a-1) below and a structural unit represented by formula (2a-2) below, and resin (2b) containing a structural unit represented by formula (2b) below. These resins have functional groups in their structural units that have high affinity for water, and are not only highly water-soluble but also highly compatible with other components in the dicing protective film composition, making it possible to more effectively suppress changes in absorbance over time and changes in the number of defects over time.

[0046]

[0047] The water-soluble resin may be used alone or in combination of two or more. A suitable example of a combination of two or more resins is, for example, at least two selected from the group consisting of polyvinyl alcohol resins, vinyl resins, and cellulose resins. The various resins described above can be used. An example of a combination of two or more polyvinyl alcohol resins and vinyl resins is a combination of a polyvinyl alcohol resin and a vinyl resin. The blending ratio (mass ratio) of the polyvinyl alcohol resin and the vinyl resin is not particularly limited, but the polyvinyl alcohol:vinyl resin ratio may be 10:90 to 90:10 or 20:80 to 80:20.

[0048] (formate ion)

[0049] The protective film composition for dicing according to this embodiment contains formate ions, with a content of 300 to 6000 ppm by mass. The lower limit of the formate ion content is preferably 300 ppm by mass or more, from the viewpoint of suppressing an increase in defects, but may be 400 ppm by mass or more, or even 350 ppm by mass or more. The upper limit of this content is preferably 6000 ppm by mass or less, from the viewpoint of stability over time, but may be 5900 ppm by mass or less, or may be 5950 ppm by mass or less. The increase in defects described above can be a factor in deteriorating electrical characteristics, and suppressing the increase in defects is preferable in that it can effectively suppress such deterioration in electrical characteristics. The method for controlling the formate ion content is not particularly limited, but may include, for example, adding formic acid, its salts, or other derivatives.

[0050] (additives, etc.)

[0051] The protective film composition for dicing according to this embodiment may contain other known additives as needed, such as basic compounds, dyes, pigments, plasticizers, preservatives, surfactants, and various other additives.

[0052] (Basic Compound)

[0053] The protective film composition for dicing according to this embodiment may contain a basic compound for the purpose of making the solid content more easily soluble. The basic compound may be either an inorganic compound or an organic compound.

[0054] Specific examples of the basic compound include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, monoethanolamine, diethylamine, di-n-propylamine, diethanolamine, triethylamine, methyldiethylamine, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, 1,8-diazabicyclo[5,4,0]-7-undecene, and 1,5-diazabicyclo[4,3,0]-5-nonane.

[0055] (dye)

[0056] The dye is preferably a water-soluble dye. Specific examples of the water-soluble dye include azo dyes (monoazo and polyazo dyes, metal complex azo dyes, pyrazolone azo dyes, stilbene azo dyes, and thiazole azo dyes), anthraquinone dyes (anthraquinone derivatives and anthrone derivatives), indigoid dyes (indigoid derivatives and thioindigoid derivatives), phthalocyanine dyes, carbonium dyes (diphenylmethane dyes, triphenylmethane dyes, xanthene dyes, and acridine dyes), quinoneimine dyes (azine dyes, oxazine dyes, and thiazine dyes), methine dyes (cyanine dyes and azomethine dyes), quinoline dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes, naphthalimide dyes, perinone dyes, and other dyes.

[0057] (dye)

[0058] The dye is preferably a water-soluble dye. Specific examples of water-soluble dyes include food additive dyes such as Food Red No. 2, Food Red No. 40, Food Red No. 102, Food Red No. 104, Food Red No. 105, Food Red No. 106, Food Yellow NY, Food Yellow No. 4 Tartrazine, Food Yellow No. 5, Food Yellow No. 5 Sunset Yellow FCF, Food Orange AM, Food Vermilion No. 1, Food Vermilion No. 4, Food Vermilion No. 101, Food Blue No. 1, Food Blue No. 2, Food Green No. 3, Food Melon Color B, and Food Egg Color No. 3. Food additive dyes are preferred from the viewpoint of low environmental impact, etc.

[0059] (Plasticizer)

[0060] Use of a plasticizer can more effectively suppress the occurrence of cracks in the protective film and can also more effectively improve the flexibility, elasticity, laser processability, etc. of the protective film. Specific examples of plasticizers include monosaccharides and disaccharides.

[0061] (preservatives)

[0062] It is preferable to use a preservative from the viewpoint of further improving the antiseptic effect of the protective film composition for dicing according to this embodiment and further reducing the burden of treating waste liquid after washing semiconductor wafers.

[0063] (Surfactant)

[0064] The surfactant is used, for example, to improve the defoaming property during the production of the dicing protective film composition, the stability of the dicing protective film composition, and the coatability of the dicing protective film composition. From the viewpoint of the defoaming property during the production of the dicing protective film composition, a surfactant may be used. As the surfactant, a water-soluble surfactant is preferably used. Examples of the surfactant include a nonionic surfactant, a cationic surfactant, an anionic surfactant, and an amphoteric surfactant.

[0065] The protective film is formed, for example, by spin-coating a protective film composition for dicing. However, when forming the protective film, irregularities due to air bubbles may occur. To prevent such irregularities, an antifoaming agent such as a surfactant may be used.

[0066] (water, organic solvent)

[0067] The protective film composition for dicing according to this embodiment contains water from the viewpoint of dissolving the above-mentioned solid components and from the viewpoint of removing the protective film for dicing by washing with water. As the water, pure water, ultrapure water (DIW), ionized water, distilled water, purified water, etc. can be used.

[0068] The protective film composition for dicing according to this embodiment preferably further contains an aqueous organic solvent as needed. The solvent is more preferably a mixed solvent containing water and an aqueous organic solvent.

[0069] The aqueous organic solvent is not particularly limited, but is preferably at least one selected from the group consisting of glycol-based solvents, alcohol-based solvents, ketone-based solvents, lactone-based solvents, ester-based solvents, sulfonic acid-based solvents, amide-based solvents, and pyrrolidone-based solvents, and more preferably at least one selected from the group consisting of glycol-based solvents and alcohol-based solvents.

[0070] Examples of glycol-based solvents include glycols, glycol ether-based solvents, and glycol ester-based solvents.

[0071] Specific examples of glycols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, furfuryl alcohol, and hexylene glycol.

[0072] Specific examples of glycol ether solvents include alkylene glycol monoalkyl ethers, alkylene glycol dialkyl ethers, and polymer-type polyalkylene glycol ether solvents.

[0073] Examples of alkylene glycol monoalkyl ethers include ethylene-based glycol monoalkyl ethers such as ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, ethylene glycol monohexyl ether, and diethylene glycol monohexyl ether; and propylene-based glycol monoalkyl ethers such as propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether (DPM), dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, and tripropylene glycol monobutyl ether.

[0074] Examples of alkylene glycol dialkyl ethers include ethylene-based glycol dialkyl ethers such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dibutyl ether, triethylene glycol dibutyl ether, ethylene glycol dihexyl ether, and diethylene glycol dihexyl ether; and propylene-based glycol dialkyl ethers such as propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dipropyl ether, propylene glycol dibutyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol dipropyl ether, dipropylene glycol dibutyl ether, tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, and tripropylene glycol dibutyl ether.

[0075] Examples of polyalkylene glycol ethers include polyoxypropylene butyl ether, polyoxyethylene polyoxypropylene butyl ether, polyoxyethylene oleyl ether, and polyoxyethylene polyoxypropylene-2-ethylhexyl ether.

[0076] Among these, ethylene-based glycol monoalkyl ethers, propylene-based glycol monoalkyl ethers, ethylene-based glycol dialkyl ethers, propylene-based glycol dialkyl ethers, etc. are preferred, and propylene glycol monomethyl ether (PGME) and the like are more preferred.

[0077] Specific examples of glycol ester solvents include alkylene glycol monoalkyl ether acetates.

[0078] Examples of the alkylene glycol monoalkyl ether acetate include ethylene-based glycol ether acetates such as ethylene glycol monobutyl ether acetate and diethylene glycol monobutyl ether acetate; and propylene-based glycol ether acetates such as propylene glycol monomethyl ether acetate (PGMEA), dipropylene glycol monomethyl ether acetate and propylene glycol diacetate.

[0079] Among these, ethylene glycol ether acetates and propylene glycol ether acetates are preferred, with propylene glycol monomethyl ether acetate (PGMEA) being more preferred.

[0080] Specific examples of alcohol-based solvents include aliphatic alcohols such as methanol, ethanol, denatured ethanol, isopropanol, n-propanol, n-butanol, and 3-methoxy-3-methyl-1-butanol.

[0081] Specific examples of ketone solvents include acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), diisobutyl ketone, cyclohexanone, cyclopentanone, diacetone alcohol, 1-hexanone, 2-hexanone, 4-heptanone, 2-heptanone, 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetylacetone, acetonylacetone, phenylacetone, acetophenone, methyl naphthyl ketone, methylcyclohexanone, ionone, isophorone, propylene carbonate (propylene carbonate), diacetonyl alcohol, and acetylcarbinol.

[0082] Specific examples of lactone solvents include γ-butyrolactone, α-methyl-γ-butyrolactone, β-propiolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone, γ-laurolactone, and hexanolactone.

[0083] Specific examples of ester-based solvents include methyl acetate, ethyl acetate, butyl acetate, amyl acetate, propyl acetate, isopropyl acetate, methyl lactate, ethyl lactate, butyl lactate, ethyl methoxyacetate, ethyl ethoxyacetate, 2-methoxybutyl acetate (2-methoxybutyl acetate), 3-methoxybutyl acetate (3-methoxybutyl acetate), 4-methoxybutyl acetate (4-methoxybutyl acetate), 3-methoxy-3-methylbutyl acetate (3-methoxy-3-methylbutyl acetate), 3-ethyl-3-methoxybutyl acetate (3-ethyl-3-methoxybutyl acetate), 4-methyl-4-methoxypentyl acetate, ethyl lactate, propyl lactate, and butyl lactate.

[0084] Specific examples of sulfonic acid solvents include dimethyl sulfone, diethyl sulfone, tetramethylene sulfone, dipropyl sulfone, sulfolane (also known as tetramethylene sulfone), 3-methyl sulfolane, 2,4-dimethyl sulfolane, 3,4-dimethyl sulfolane, diphenyl sulfolane, 3,4-diphenylmethyl sulfolane, sulfolene, 3-methyl sulfolene, and 3-ethyl sulfolene.

[0085] Specific examples of amide solvents include N,N-dimethylformamide (DMF), diethylformamide (DEF), N,N-dimethylacetamide (DMAc), N-methylpyrrolidine (MPD), and hexamethylphosphoric triamide (HMPA).

[0086] Specific examples of pyrrolidone solvents include N-methylpyrrolidone (NMP), 2-pyrrolidone, and N-vinyl-2-pyrrolidone.

[0087] The protective film composition for dicing according to this embodiment may contain one or more of the above-mentioned aqueous organic solvents, but preferably contains two or more aqueous organic solvents. In a preferred example of containing two or more aqueous organic solvents, two or more of the above-mentioned organic solvents can be selected.

[0088] Incidentally, as an example of a combination of water and an aqueous organic solvent in a mixed solvent, a mixed solvent containing water and at least one selected from the group consisting of glycol-based solvents and alcohol-based solvents is preferred; a mixed solvent containing water and at least one selected from the group consisting of glycol ether-based solvents, glycol ester-based solvents, and alcohol-based solvents is more preferred; a mixed solvent containing water and at least one selected from the group consisting of propylene glycol monomethyl ether (PGME), methanol, ethanol, denatured ethanol, isopropanol, n-propanol, n-butanol, and 3-methoxy-3-methyl-1-butanol is even more preferred; and a mixed solvent containing water and propylene glycol monomethyl ether (PGME) is even more preferred.

[0089] The mixing ratio of water and an aqueous organic solvent in the mixed solvent is not particularly limited, but the water content is preferably 30 to 99 parts by mass per 100 parts by mass of the total amount of water and the aqueous organic solvent. The lower limit of this water content is more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, even more preferably 60 parts by mass or more, and even more preferably 70 parts by mass or more. The upper limit of this water content is more preferably 95 parts by mass or less, even more preferably 90 parts by mass or less.

[0090] (solid content concentration)

[0091] The solid content concentration of the dicing protective film composition according to this embodiment is not particularly limited, but is preferably 1 to 90% by mass. The lower limit of the solid content concentration is more preferably 5% by mass or more, and even more preferably 10% by mass or more. The upper limit of the solid content concentration is more preferably 80% by mass or less, even more preferably 60% by mass or less, even more preferably 40% by mass or less, and even more preferably 30% by mass or less. In measuring the solid content concentration, the components excluding the solvent (water, organic solvent, etc.) from the total amount of the dicing protective film composition are defined as the "solid content." The "solid content concentration" is the ratio of the total amount of components other than the solvent contained in the dicing protective film composition to the total amount of the dicing protective film composition (total amount of components other than the solvent contained in the dicing protective film composition / total amount of the dicing protective film composition (% by mass)).

[0092] <Wafer manufacturing method and processing method>

[0093] According to this embodiment, a wafer can be manufactured by applying the above-described protective film composition for dicing to a substrate or the like to be protected to form a protective film (protective film for dicing), and then dicing. A method for manufacturing such a wafer preferably includes a film-forming step of applying the above-described protective film composition for dicing to the processing surface of the wafer to form a protective film, and a processing step of irradiating the processing surface with laser light through the protective film to process it. Furthermore, it is more preferable that the method further includes a step of removing the protective film by washing with water after the processing step.

[0094] The present embodiment is also suitable as a wafer processing method using the above-described protective film composition for dicing. Such a wafer processing method preferably includes a film-forming step of applying the above-described protective film composition for dicing to form a protective film, and a processing step of irradiating a processing surface with laser light through the protective film to perform processing.

[0095] The coating method in the film-forming step is not particularly limited, and spin coating, spray coating, die coating, roll coating, flow coating, curtain coating, etc. can be used depending on the shape and material of the substrate, etc., but spin coating is preferred. Furthermore, after coating, post-treatments such as a drying step such as natural drying or hot air drying, or a light irradiation step such as ultraviolet irradiation, may be performed.

[0096] When applying by spin coating, for example, the following steps are performed: (a) a step (discharge step) of applying the dicing protective film composition to an object to be coated (such as a semiconductor wafer) fixed on the stage of a spin coater, (b) a step (rotation processing step) of removing excess dicing protective film composition by centrifugal force by rotating the stage to form a thin film, and (c) a step (drying step) of removing the workpiece from the spin coater and forming a thin film by natural drying, hot air drying, etc. Spin coating is preferred because it has the advantages of enabling film formation with little deviation in film thickness and can be performed without a vacuum, resulting in excellent film formation costs and film formation speed.

[0097] The thickness of the protective film is not particularly limited, but is generally preferably 0.1 to 100 μm in order to facilitate removal of the protective film by washing with water after processing and to ensure the durability of the protective film against irradiation with laser light, as described below. The lower limit of the film thickness is more preferably 1 μm or more, and even more preferably 3 μm or more. The upper limit of the film thickness is more preferably 50 μm or less, even more preferably 30 μm or less, even more preferably 20 μm or less, and even more preferably 10 μm or less. In this regard, when the protective film is formed by spin coating, for example, a film thickness within the above range can be more effectively formed with excellent film formability and selectivity.

[0098] In the processing step, laser dicing is preferably performed, in which a laser beam is irradiated onto the processing surface. Laser dicing allows processing to be performed without contacting the wafer to be processed, and therefore defects such as cracks and chipping can be effectively suppressed. Specifically, the wafer has multiple semiconductor chips formed thereon, each separated by a grid-like street, and the processing step is more preferably a step in which a laser beam is irradiated onto the streets through a protective film to form grooves. These grooves are processed grooves with a pattern corresponding to the shape of the semiconductor chips.

[0099] The protective film composition for dicing and the protective film according to this embodiment are expected to improve film-forming properties, straightness of the processed groove (straightness of the sidewalls of the protective film that constitute the processed groove), and rectangularity of the cross section of the processed groove (rectangularity of the cross section of the protective film that constitutes the processed groove). Excellent processability allows accurate processing without deviation from the desired position, making it possible to process with even higher positional accuracy.

[0100] From the viewpoint of intensity, the laser light is preferably an ultraviolet laser with a wavelength of 100 to 400 nm, or a YVO4 laser or YAG laser with a wavelength of 266 nm, 355 nm, or the like.

[0101] The laser beam irradiation in the groove forming step can be carried out under the following processing conditions, for example. The diameter of the focused spot can be appropriately selected taking into consideration the width of the groove. Laser beam source: YVO4 laser or YAG laser Laser beam wavelength: 355 nm Laser beam repetition frequency: 50 to 100 kHz Laser beam output: 0.1 to 4.0 W Laser beam processing feed rate: 1 to 800 mm / sec

[0102] Then, after irradiating the laser beam along the predetermined streets, the semiconductor wafer held on the chuck table is indexed and moved by the distance corresponding to the street spacing, and the laser beam can be irradiated again. After irradiating the laser beam and indexing the movement along all the streets extending in the predetermined direction in this manner, the semiconductor wafer held on the chuck table is rotated 90 degrees. Then, irradiating the laser beam and indexing the movement along each street extending perpendicular to the predetermined direction in the same manner as above is performed. In this manner, machining grooves can be formed along the streets formed in the stack on the semiconductor wafer.

[0103] Furthermore, a cutting step may be performed in which the wafer is cut at the positions of the processing grooves (positions corresponding to the positions of the streets) provided on the processing surface of the wafer. When the cutting step is performed, this is suitable for a method of manufacturing semiconductor chips.

[0104] After the dicing step, the protective film covering the surface of the semiconductor chip is removed. Since the protective film composition for dicing according to this embodiment contains a water-soluble resin, the protective film can be efficiently washed away with water.

[0105] An example of a method for manufacturing and processing a semiconductor wafer has been described above. According to the above-described method of this embodiment, by using a protective film formed from the protective film composition for dicing of this embodiment, debris can be effectively removed by washing after dicing. This is particularly suitable for washing with water. The protective film composition for dicing of this embodiment contains a predetermined ultraviolet absorber and a water-soluble resin, and the content of formate ions is controlled to a predetermined ratio. This effectively prevents peeling or chipping of the protective film formed on the wafer. Furthermore, it is possible to prevent a decrease in absorbance over time and an increase in the number of defects over time. Therefore, it is also possible to effectively prevent unintended peeling of the protective film during laser processing.

[0106] The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples. Unless otherwise specified, the quantities are based on mass, and the experiments were carried out at 25°C and atmospheric pressure.

[0107] <Ingredients>

[0108] The components used in the examples and comparative examples are listed below: PVA: Polyvinyl alcohol (saponification degree 75%, manufactured by Kuraray Co., Ltd., "Poval (registered trademark) PVA5-74LLA") PVP: Polyvinylpyrrolidone (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., "PVP K90") Ferulic acid Water: DIW (ultrapure water) PGME: Propylene glycol monomethyl ether Formate ions: Formic acid was added to achieve a predetermined formate ion concentration.

[0109] <Preparation of protective film composition for dicing>

[0110] Dicing protective film compositions (hereinafter sometimes referred to as "chemical solutions") were prepared by mixing the components to obtain the compositions shown in Table 1. The solid content concentration in Table 1 refers to the concentration of the components contained in the resulting chemical solutions, excluding the solvent. For example, Example 1 is a liquid dicing protective film composition containing 100 parts by mass of PVA and 5 parts by mass of ferulic acid, dissolved in a mixed solvent of water and PGME at a mixing ratio of 80:20 by mass (water / PGME) so as to obtain a solid content concentration of 20% by mass, and containing 6,000 ppm by mass of formate ions. Furthermore, for example, Example 13 is a liquid protective film composition for dicing, which contains 100 parts by mass of a resin in which the mixing ratio of PVA and PVP (PVA / PVP) is 50:50 by mass and 5 parts by mass of ferulic acid, and is dissolved in a mixed solvent in which the mixing ratio of water and PGME (water / PGME) is 80:20 by mass so that the solid content concentration becomes 15% by mass, and the content of formate ions is 2000 ppm by mass.

[0111] (Measurement of solids concentration)

[0112] The solid content concentration was calculated as the total amount of components other than the solvent contained in the "chemical solution" divided by the total amount of the "chemical solution" (% by mass).

[0113] (Measurement of formate ions)

[0114] The amount of formate ions in the protective film composition for dicing was determined by ion chromatography.

[0115] <Evaluation of absorbance>

[0116] The chemical solutions of each Example and Comparative Example were stored in a polyethylene tank for a predetermined period (initial, 2 weeks, 1 month) in a light-shielded environment at 40°C. The absorbance was measured using an ultraviolet-visible spectrophotometer (UV-vis) and the gram absorption coefficient (unit: L / g cm) was used.

[0117] <Evaluation of the number of defects>

[0118] First, the chemical solution of each example and each comparative example was applied to the surface of a silicon substrate (12-inch Si substrate) using a spinner at 2000 rpm for 120 seconds. Thereafter, the substrate was allowed to dry naturally at room temperature for 10 minutes to form a protective film with a thickness of 1 μm.

[0119] Subsequently, the protective film was rinsed with pure water for 300 seconds and then dried.

[0120] The number of defects was determined by counting the number of foreign particles with a maximum diameter greater than 300 nm using a wafer defect inspection device (KLA-Tencor Corporation, "Surfscan SP5"). Measurements were performed immediately after preparation of the chemical solution ("initial"), one week after preparation of the chemical solution ("1W"), and one month after preparation of the chemical solution ("1M"). The number of defects in the "initial" state (immediately after preparation) of Example 1 was set as a reference value of "1," and the number of defects in each Example and Comparative Example was calculated as a relative ratio to this reference value. If the value at "1M (after one month)" could be kept to three times or less the "initial" value of Example 1, the defect was deemed to have practically usable characteristics in terms of electrical properties, etc., and was therefore determined as "A" (pass).

[0121] For example, in the case of Example 2, the number of defects in the "initial stage" was 1.1 times that of Example 1, the number of defects in "2W (after two weeks)" was 1.2 times that of Example 1, and the number of defects in "1M (after one month)" was 1.3 times that of Example 1, indicating that the result was "A" (pass).

[0122] For example, in the case of Comparative Example 1, the number of defects in the "initial stage" was 1.3 times that of Example 1 in the "initial stage," the number of defects in "2W (after two weeks)" was 2.2 times that of Example 1 in the "initial stage," and the number of defects in "1M (after one month)" was 3.2 times that of Example 1 in the "initial stage," indicating a grade of "B" (failure).

[0123] The compositions of the examples and comparative examples are shown in Table 1, and the evaluation results of the examples and comparative examples are shown in Table 2.

[0124]

[0125]

[0126] From the above, it was at least confirmed that the protective film composition for dicing according to this example can suppress the decrease in absorbance over time and can suppress the increase in the number of defects over time.

[0127] This application is based on a Japanese patent application (Patent Application No. 2023-222778) filed with the Japan Patent Office on December 28, 2023, the contents of which are incorporated herein by reference.

Claims

1. A dicing protective film composition containing an ultraviolet absorber containing a compound (1) represented by the following general formula (1), a water-soluble resin, formate ions, and water, wherein the content of the formate ions is 300 to 6000 mass ppm. (In the formula, X represents a hydrogen atom, -OR １ represents. R １ represents a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms. n represents a number from 1 to 5, and m represents a number from 0 to 4.) 2. The dicing protective film composition according to claim 1, wherein the ultraviolet absorber is at least one selected from the group consisting of ferulic acid, 2-hydroxybenzoic acid, 4-hydroxybenzoic acid, 2,3-dihydroxybenzoic acid, and 3,4-dihydroxybenzoic acid.

3. The water-soluble resin is at least one resin selected from the group consisting of a resin (2a) containing a structural unit represented by the following formula (2a-1) and a structural unit represented by the following formula (2a-2), and a resin (2b) containing a structural unit represented by the following formula (2b). The dicing protective film composition according to claim 1.

4. The dicing protective film composition according to claim 1, further containing an aqueous organic solvent.

5. The dicing protective film composition according to claim 4, wherein the aqueous organic solvent is at least one selected from the group consisting of glycol solvents and alcohol solvents.

6. The dicing protective film composition according to claim 5, containing two or more aqueous organic solvents as the aqueous organic solvent.

7. The dicing protective film composition according to claim 1, having a solid content concentration of 1 to 90% by mass.

8. A method for manufacturing a wafer, comprising: a film forming step of applying the dicing protective film composition according to claim 1 to a processed surface of the wafer to form a protective film; and a processing step of irradiating the processed surface with laser light through the protective film to perform processing.

9. The method for manufacturing a wafer according to claim 8, wherein a plurality of semiconductor chips partitioned by grid-like streets are formed on the wafer, and the processing step is a step of forming grooves by irradiating the streets with laser light through the protective film.

10. The method for manufacturing a wafer according to claim 8, further comprising a step of removing the protective film by water washing after the processing step.

11. A method for processing a wafer, comprising: a film forming step of applying the dicing protective film composition according to claim 1 to a processed surface of the wafer to form a protective film; and a processing step of irradiating the processed surface with laser light through the protective film to perform processing.

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