Protective film forming agent and method for producing semiconductor chip

Abstract

The present invention provides a protective film forming agent used for forming a protective film on the surface of a semiconductor wafer during the dicing of a semiconductor wafer, which can form a protective film with excellent laser processability and has excellent solubility of a light absorber, and a method for manufacturing a semiconductor chip using the protective film forming agent. The protective film forming agent comprises a water-soluble resin (A), a light absorber (B), an alkaline compound (C) and a solvent (S). The alkaline compound (C) is preferably an alkylamine, an alkanolamine, an imidazole compound, ammonia or an alkali metal hydroxide. The content of the light absorber (B) in the protective film forming agent is preferably 0.1 mass % or more and 10 mass % or less.

Description

Technical Field

[0001] The present invention relates to a protective film forming agent and a method for producing a semiconductor chip using the protective film forming agent. Background Art

[0002] In the wafer formed in the semiconductor device manufacturing process, the stacked body obtained by stacking insulating films and functional films on the surface of a semiconductor substrate such as silicon is divided by grid-like predetermined dividing lines called streets, and each area divided by the streets becomes a semiconductor chip such as IC and LSI.

[0003] By cutting the wafer along the blocks, multiple semiconductor chips are obtained. In addition, in the optical device wafer, the blocks are used to divide the stacked body of the gallium nitride compound semiconductor and the like into multiple areas. By cutting along the blocks, the optical device wafer is divided into optical devices such as light-emitting diodes and laser diodes. These optical devices are widely used in electrical equipment.

[0004] Conventionally, such cutting along the blocks of the wafer is performed using a cutting device called a dicer. However, in this method, since the wafer having a stacked structure is a highly brittle material, when the wafer is cut and divided into semiconductor chips by a cutting tool (cutting blade), there are problems such as damage or defect or peeling of the insulating film formed on the surface of the chip, which is necessary for the circuit element.

[0005] In order to eliminate such undesirable situations, the following method has been proposed: a mask containing a layer of water-soluble material is formed on the surface of a semiconductor substrate, and then a laser is irradiated on the mask to decompose and remove a portion of the mask to expose the surface of the semiconductor substrate in a portion of the mask, and then the semiconductor substrate exposed from a portion of the mask is cut off by plasma etching, thereby dividing the semiconductor substrate into semiconductor chips (ICs) (see patent document 1).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application No. 2014-523112 Summary of the invention

[0009] Technical problem to be solved by the invention

[0010] When forming a protective film as a mask by the method described in Patent Document 1, a water-soluble ultraviolet absorber or other light absorbent is often used together with a water-soluble resin. The protective film as a mask is required to be decomposable and removable by laser, that is, laser processability. By using a light absorbent, laser processability can be improved.

[0011] Furthermore, in recent years, as the thickness of the protective film tends to be thicker than before, in order to further improve laser processability, it is often necessary to increase the amount of light absorber added to the protective film forming agent. When a large amount of light absorber is added to the protective film forming agent, there is a problem that the light absorber is difficult to dissolve in the solvent.

[0012] The present invention has been completed in view of the above-mentioned technical problems, and its purpose is to provide a protective film forming agent that is used to form a protective film on the surface of a semiconductor wafer during the cutting of the semiconductor wafer, which can form a protective film with excellent laser processability and has excellent solubility of a light absorber, and a method for manufacturing a semiconductor chip using the protective film forming agent.

[0013] Solutions for solving the above technical problems

[0014] The present inventors have found that the above-mentioned technical problems can be solved by blending a basic compound (C) into a protective film forming agent comprising a water-soluble resin (A), a light absorber (B) and a solvent (S), and have thus completed the present invention. More specifically, the present invention provides the following solutions.

[0015] A first aspect of the present invention is a protective film forming agent used to form a protective film on the surface of a semiconductor wafer during dicing of the semiconductor wafer.

[0016] The invention comprises a water-soluble resin (A), a light absorber (B), a basic compound (C) and a solvent (S).

[0017] A second embodiment of the present invention is a method for manufacturing a semiconductor chip, which is a method for manufacturing a semiconductor chip by processing a semiconductor wafer, comprising:

[0018] The protective film forming agent of the first embodiment is applied on the semiconductor wafer to form a protective film;

[0019] Laser light is irradiated onto predetermined positions of one or more layers including a protective film on a semiconductor wafer to expose the surface of the semiconductor wafer and form a processing groove having a pattern corresponding to the shape of the semiconductor chip.

[0020] Effects of the Invention

[0021] According to the present invention, there can be provided a protective film forming agent which is used in a semiconductor chip manufacturing method for manufacturing a semiconductor chip from a semiconductor wafer to form a protective film on the surface of a semiconductor wafer, the protective film forming agent being capable of forming a protective film having excellent laser processability and having excellent solubility of a light absorber, and a semiconductor chip manufacturing method using the protective film forming agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1This is a perspective view showing a semiconductor wafer processed by the wafer processing method using the protective film forming agent of the present invention.

[0023] Figure 2 yes Figure 1 An enlarged cross-sectional view of a semiconductor wafer is shown.

[0024] Figure 3 This is an enlarged cross-sectional view of a main part of a semiconductor wafer on which a protective film is formed.

[0025] Figure 4 This is a perspective view showing a state in which a semiconductor wafer having a protective film formed thereon is supported by a ring-shaped frame via a protective tape.

[0026] Figure 5 This is a perspective view of the main parts of a laser processing device that implements a laser beam irradiation process.

[0027] Figure 6 This is an enlarged cross-sectional view of a semiconductor wafer having a protective film and a processing groove formed by laser irradiation.

[0028] Figure 7 It shows Figure 6 An explanatory diagram of plasma irradiation of a semiconductor wafer is shown.

[0029] Figure 8 This is an enlarged cross-sectional view showing a state where a semiconductor wafer is divided into semiconductor chips by plasma irradiation.

[0030] Fig. 9 This is an enlarged cross-sectional view showing a state where the protective film on the semiconductor chip is removed. DETAILED DESCRIPTION

[0031] 《Protective film forming agent》

[0032] In the dicing of semiconductor wafers, a protective film forming agent is used to form a protective film on the surface of the semiconductor wafer. The protective film forming agent includes a water-soluble resin (A), a light absorber (B), a basic compound (C) and a solvent (S). Hereinafter, the protective film forming agent is also described as a "protective film forming agent".

[0033] Specifically, the protective film forming agent is preferably used to form a protective film in a method for manufacturing a semiconductor chip, the method comprising: irradiating a protective film formed on a semiconductor wafer with a laser to expose the surface of the semiconductor wafer and to form a processing groove having a pattern corresponding to the shape of the semiconductor chip;

[0034] The semiconductor wafer including the protective film and the processed groove is irradiated with laser light or plasma, thereby processing the position of the processed groove in the semiconductor wafer.

[0035] From the perspective of facilitating the removal of the protective film by water washing after processing of the semiconductor wafer, or from the perspective of sufficient durability of the protective film against plasma irradiation when plasma irradiation is performed in the semiconductor chip manufacturing method described later, the film thickness of the protective film is typically preferably 1 μm to 100 μm, more preferably 10 μm to 100 μm, and further preferably 30 μm to 100 μm.

[0036] When laser irradiation is performed, the thickness of the protective film is preferably 0.1 μm or more and 10 μm or less.

[0037] Hereinafter, essential or optional components contained in the protective film forming agent will be described.

[0038] <Water-soluble resin (A)>

[0039] The water-soluble resin (A) is a base material of the protective film formed using the protective film forming agent. The type of the water-soluble resin is not particularly limited as long as it is a resin that can be dissolved in a solvent such as water and applied and dried to form a film.

[0040] Water-soluble means that 0.5 g or more of the solute (water-soluble resin) is dissolved in 100 g of water at 25°C.

[0041] The water-soluble resin (A) preferably shows a weight loss rate of 80% by weight or more when heated to 500° C. in thermogravimetric measurement. The weight loss rate when heated to 500° C. is more preferably 90% by weight or more, and further preferably 95% by weight or more.

[0042] When using a protective film forming agent containing a water-soluble resin (A) whose weight loss rate when heated to 500°C is within the above-mentioned range, since the decomposition of the water-soluble resin (A) in the protective film is well promoted by the energy of the laser, it is easy to form a well-opened processing groove in the protective film by laser irradiation.

[0043] The water-soluble resin (A) preferably has a weight reduction rate of 10% by weight or more, more preferably 15% by weight or more, when heated to 350° C. in thermogravimetric measurement.

[0044] When the water-soluble resin (A) is used, the water-soluble resin (A) is easily decomposed even when the amount of energy imparted by the laser is small, and even when a low-power laser is irradiated, a well-opened processed groove is easily formed in the protective film.

[0045] Thermogravimetric measurement for determining the weight reduction rate can be performed according to a general thermogravimetric measurement method.

[0046] Regarding the water-soluble resin (A), the method for adjusting the weight loss rate is not particularly limited. Generally, if the resins are of the same type, the smaller the average molecular weight, the higher the weight loss rate of the water-soluble resin (A).

[0047] From the viewpoint of achieving a balance between decomposability and film-forming properties during laser irradiation, the weight average molecular weight of the water-soluble resin (A) is preferably from 15,000 to 300,000, and more preferably from 20,000 to 200,000.

[0048] Specific examples of the type of the water-soluble resin (A) include ethylene-based resins, cellulose-based resins, polyethylene oxide, polyglycerol, and water-soluble nylon.

[0049] The vinyl resin is not particularly limited as long as it is a homopolymer or copolymer of a monomer having a vinyl group and is water-soluble. Examples of the vinyl resin include polyvinyl alcohol, polyvinyl acetal (including vinyl acetate copolymers), polyvinyl pyrrolidone, polyacrylamide, poly(N-alkylacrylamide), polyallylamine, poly(N-alkylallylamine), partially amidated polyallylamine, poly(diallylamine), allylamine-diallylamine copolymer, polyacrylic acid, polyvinyl alcohol polyacrylic acid block copolymer, and polyvinyl alcohol polyacrylate block copolymer.

[0050] The cellulose resin is not particularly limited as long as it is a water-soluble cellulose derivative, and examples of the cellulose resin include methyl cellulose, ethyl cellulose and hydroxypropyl cellulose.

[0051] In addition, the water-soluble resin (A) preferably has no acidic group.

[0052] These may be used alone or in combination of two or more.

[0053] Among the specific examples of the water-soluble resin (A), vinyl resins and cellulose resins are preferred, and polyvinyl pyrrolidone and hydroxypropyl cellulose are more preferred, because the shape of the processed groove is less likely to deteriorate due to thermal collapse of the protective film.

[0054] Usually, at an appropriate time point after the processing groove is formed according to the method of processing the semiconductor wafer with the protective film and the processing groove into the semiconductor chip, the protective film formed on the surface of the semiconductor wafer is removed from the surface of the semiconductor wafer or the semiconductor chip. Therefore, from the viewpoint of the water washability of the protective film, a water-soluble resin with low affinity to the surface of the semiconductor wafer is preferred. As a water-soluble resin with low affinity to the surface of the semiconductor wafer, a resin having only ether bonds, hydroxyl groups, and amide bonds as polar groups is preferred, such as polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, and hydroxypropyl cellulose.

[0055] The ratio of the mass of the water-soluble resin (A) in the protective film forming agent to the total mass of the water-soluble resin (A) and the mass of the light absorber (B) is preferably 60 mass % to 99 mass %, more preferably 80 mass % to 95 mass %, from the viewpoint of preventing the occurrence of poor opening when the processed groove is formed by irradiating the protective film with a laser or deterioration in the shape of the processed groove due to thermal collapse of the protective film.

[0056] <Light Absorber (B)>

[0057] As the light absorber (B), those generally used in protective film forming agents can be used.

[0058] As the light absorber (B), a water-soluble light absorber such as a water-soluble dye, a water-soluble pigment or a water-soluble ultraviolet absorber is preferably used. The water-soluble light absorber is advantageous in that it is uniformly present in the protective film. Examples of the water-soluble light absorber include organic acids having a carboxyl group or a sulfonic group; sodium salts, potassium salts, ammonium salts and quaternary ammonium salts of organic acids; and compounds having a hydroxyl group.

[0059] When a water-soluble light absorber is used, the storage stability of the protective film forming agent is high, and during storage of the protective film forming agent, the occurrence of undesirable conditions such as phase separation of the protective film forming agent and sedimentation of the light absorber can be suppressed, which is also advantageous in that the good coating properties of the protective film forming agent can be easily maintained for a long time.

[0060] In addition, water-insoluble light absorbers such as pigments can also be used. When a water-insoluble light absorber is used, although there will be no fatal hindrance in the use of the protective film forming agent, there may be a deviation in the laser absorption ability of the protective film, or it may be difficult to obtain a protective film forming agent with excellent storage stability or coating properties, or it may be difficult to form a protective film of uniform thickness.

[0061] Examples of the light absorber (B) include benzophenone compounds, cinnamic acid compounds, anthraquinone compounds, naphthalene compounds, and biphenyl compounds.

[0062] The benzophenone compound may be a compound represented by the following formula (B1). The compound represented by the following formula (B1) is preferred because it allows the protective film to efficiently absorb the energy of the laser and promotes thermal decomposition of the protective film.

[0063] [Chemistry 1]

[0064]

[0065] (In formula (B1), R 1 and R 3 are independently hydroxyl or carboxyl, R 2 and R 4are independently hydroxyl, carboxyl or -NR 5 R 6 The group represented by R 5 and R 6 Each of them is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and m and n are each independently an integer of 0 to 2.)

[0066] The compound represented by the above formula (B1) has a high absorption coefficient and shows a high absorption coefficient even when added to the protective film forming agent together with a base. Therefore, when a protective film is formed using a protective film forming agent containing the compound represented by the above formula (B1) as a light absorber (B), a portion of the protective film can be decomposed by laser light when forming a mask for dicing.

[0067] In the above formula (B1), R 2 and R 4 Sometimes with -NR 5 R 6 Represents a group. 5 and R 6 Each of R is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. 5 and R 6 The alkyl group of R may be straight chain or branched. 5 and R 6 Specific examples of the alkyl group are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl.

[0068] As a 5 R 6 The group represented by is preferably an amino group, a methylamino group, an ethylamino group, a dimethylamino group, and a diethylamino group, and more preferably an amino group, a dimethylamino group, and a diethylamino group.

[0069] The compound represented by the formula (B1) is preferably a compound represented by the following formula (B1-1) because the extinction coefficient is high in the presence of a base.

[0070] [Chemistry 2]

[0071]

[0072] (In formula (B1-1), R 1 ~R 4 , m and n are the same as those in formula (B1).

[0073] In view of the high absorption coefficient in the presence of a base, it is preferred that in the above formula (B1) and formula (B1-1), R 1 and R 3 At least one of the groups is a hydroxyl group.

[0074] The compound represented by the formula (B1-1) is preferably a compound represented by any one of the following formulas (B1-1a) to (B1-1e).

[0075] [Chemistry 3]

[0076]

[0077] (In formula (B1-1a) to formula (B1-1e), R 1 ~R 4 With R in formula (B1) 1 ~R 4 same.)

[0078] Among the compounds represented by formula (B1-1a) to formula (B1-1e), the compound represented by formula (B1-1a) is preferred.

[0079] Among the compounds represented by formula (B1-1a) to formula (B1-1e), R 2 For -NR 5 R 6 The above group represented by R 5 and R 6 Each independently is an alkyl group having 1 to 4 carbon atoms.

[0080] Preferred specific examples of the compound represented by formula (B1) include the following compounds.

[0081] These compounds are preferred compounds in view of their easy availability and the fact that they show a high absorption coefficient even in the presence of a base.

[0082] [Chemistry 4]

[0083]

[0084] When the light absorber (B) contains a compound represented by formula (B1), the ratio of the mass of the compound represented by formula (B1) to the mass of the light absorber (B) is not particularly limited within the range not hindering the purpose of the present invention. The ratio of the mass of the compound represented by formula (B1) to the mass of the light absorber (B) is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 95% by mass or more, and particularly preferably 100% by mass.

[0085] Examples of benzophenone compounds include 4,4′-dicarboxybenzophenone, benzophenone-4-carboxylic acid, and tetrahydroxybenzophenone, all of which are water-soluble ultraviolet absorbers.

[0086] The cinnamic acid compound may be a compound represented by the following formula (B2). The compound represented by the following formula (B2) is preferred because it allows the protective film to efficiently absorb the energy of the laser and promotes thermal decomposition of the protective film.

[0087] [Chemistry 5]

[0088]

[0089] (In formula (B2), R 11 is hydroxyl, alkoxy or -NR 12 R 13 The group represented by R 12 and R 13 are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, p is an integer of 0 to 3, and when p is 2 or more, a plurality of R 11 Can be the same or different.)

[0090] In the above formula (B2), R 11 The alkoxy group of R may be straight chain or branched. 11 The alkoxy group of R is preferably an alkoxy group having 1 to 4 carbon atoms. 11 Specific examples of the alkoxy group are methoxy, ethoxy, n-propoxy, isopropoxy and n-butoxy.

[0091] In the above formula (B2), R 11 Sometimes with -NR 12 R 13 Represents a group. 12 and R 13 Each of R is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. 12 and R 13 The alkyl group of R may be straight chain or branched. 12 and R 13 Specific examples of the alkyl group are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl.

[0092] The compound represented by the formula (B2) is preferably a compound represented by the following formula (B2-1).

[0093] [Chemistry 6]

[0094]

[0095] (In formula (B2-1), R 11 With R in formula (B2) 11 same.)

[0096] Specific examples of the cinnamic acid compounds include 4-aminocinnamic acid, 3-aminocinnamic acid, 2-aminocinnamic acid, sinapinic acid (3,5-dimethoxy-4-hydroxycinnamic acid), ferulic acid, and caffeic acid.

[0097] Among them, 4-aminocinnamic acid, 3-aminocinnamic acid, 2-aminocinnamic acid and ferulic acid are preferred, 4-aminocinnamic acid and ferulic acid are more preferred, and 4-aminocinnamic acid is particularly preferred.

[0098] Specific examples of the anthraquinone compounds include 2-carboxyanthraquinone, 2,6-anthraquinone disulfonic acid, and 2,7-anthraquinone disulfonic acid.

[0099] Specific examples of the naphthalene compound include 1,2-naphthalene dicarboxylic acid, 1,8-naphthalene dicarboxylic acid, 2,3-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, and 2,7-naphthalene dicarboxylic acid.

[0100] Specific examples of the biphenyl compounds include biphenyl-4-sulfonic acid and the like.

[0101] Examples of the light absorber (B) include water-soluble amines such as curcumin and EAB-F (4,4'-bis(diethylamino)benzophenone).

[0102] Specific examples of water-soluble dyes include azo dyes (monoazo and polyazo dyes, metal complex azo dyes, pyrazolone azo dyes, stilbene azo dyes, thiazole azo dyes), anthraquinone dyes (anthraquinone derivatives, anthrone derivatives), indigo dyes (indigo derivatives, thioindigo derivatives), phthalocyanine dyes, carbonium dyes (diphenylmethane dyes, triphenylmethane dyes, xanthene dyes, acridine dyes), quinoneimine dyes (azine dyes, oxazine dyes, thiazine dyes), methine dyes (cyanine dyes, azo methine dyes), quinoline dyes, nitroso dyes, benzoquinone and naphthoquinone dyes, naphthalimide dyes, perinone dyes and other dyes.

[0103] As the water-soluble pigment, from the viewpoint of low environmental load, for example, food additive pigments such as Edible Red No. 2, Edible Red No. 40, Edible Red No. 102, Edible Red No. 104, Edible Red No. 105, Edible Red No. 106, Edible Yellow NY, Edible Yellow No. 4 Lemon Yellow, Edible Yellow No. 5, Edible Yellow No. 5 Sunset Yellow FCF, Edible Orange AM, Edible Vermilion No. 1, Edible Vermilion No. 4, Edible Vermilion No. 101, Edible Blue No. 1, Edible Blue No. 2, Edible Green No. 3, Edible Melon Color B, and Edible Egg Yellow No. 3 are preferred.

[0104] The content of the light absorber (B) in the protective film forming agent is not particularly limited within the range not hindering the purpose of the present invention. The content of the light absorber (B) in the protective film forming agent is preferably 0.1 mass % to 10 mass %. The above-mentioned protective film forming agent has excellent solubility of the light absorber (B), so the content of the light absorber (B) can be increased.

[0105] The ratio of the mass of the light absorber (B) in the protective film forming agent to the total mass of the water-soluble resin (A) and the mass of the light absorber (B) is preferably 1% by mass to 50% by mass, more preferably 5% by mass to 40% by mass, and even more preferably 10% by mass to 40% by mass, from the viewpoint of preventing the occurrence of poor opening when the protective film is irradiated with laser to form the machined groove or deterioration in the shape of the machined groove due to thermal collapse of the protective film.

[0106] The content of the light absorbent (B) can be set so that the absorbance of the protective film formed by applying the protective film forming agent becomes a desired value. The absorbance of the protective film formed by applying the protective film forming agent is not particularly limited. For example, the absorbance of the protective film formed by applying the protective film forming agent per 1 μm film thickness at a wavelength of 355 nm is preferably 0.3 or more, more preferably 0.8 or more, and even more preferably 1.0 or more.

[0107] <Basic compound (C)>

[0108] The protective film forming agent contains a basic compound (C) as an essential component. By containing the basic compound (C), it is possible to form a protective film having excellent laser processability and having excellent solubility of the light absorber (B). Since the light absorber (B) in the protective film forming agent has excellent solubility, the content of the light absorber (B) in the protective film forming agent can be increased. In addition, since the formed protective film has excellent laser processability, it is possible to easily form a desired groove in the protective film.

[0109] As the basic compound (C), any of an inorganic compound and an organic compound can be used, and examples thereof include alkylamines, alkanolamines, imidazole compounds, ammonia, and hydroxides of alkali metals.

[0110] Specific examples of the basic compound (C) 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, imidazole, 2-methylimidazole, 1,2-methylimidazole, N-methylimidazole, 4-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, pyrrole, piperidine, 1,8-diazabicyclo[5,4,0]-7-undecene and 1,5-diazabicyclo[4,3,0]-5-nonene.

[0111] In addition, in this specification, the said basic compound (C) is defined as a component which does not correspond to a solvent (S).

[0112] The amount of the basic compound (C) used is not particularly limited within the range that does not hinder the purpose of the present invention. The amount of the basic compound (C) used is preferably 1 mol or more, more preferably 1 mol or more and 20 mol or less relative to 1 mol of the light absorber (B). The lower limit of the amount of the basic compound (C) used can be 1.5 mol or more, 2 mol or more, or 3 mol or more relative to 1 mol of the light absorber (B). The upper limit of the amount of the basic compound (C) used can be 15 mol or less, 10 mol or less, or 5 mol or less relative to 1 mol of the light absorber (B).

[0113] <Other additives>

[0114] The protective film forming agent may contain other additives in addition to the water-soluble resin (A), the light absorber (B) and the basic compound (C) unless the purpose of the present invention is impaired. Examples of other additives include antiseptics and surfactants.

[0115] As the preservative, benzoic acid, butyl paraben, ethyl paraben, methyl paraben, propyl paraben, benzalkonium chloride, benzethonium chloride, benzyl alcohol, cetylpyridinium chloride, chlorobutanol, phenol, phenylethanol, 2-phenoxyethanol, phenylmercuric nitrate, thimerosal, m-cresol, lauryl dimethylamine oxide, or a combination thereof can be used.

[0116] Not only from the perspective of the corrosion protection of the protective film forming agent, but also from the perspective of reducing the processing load of the waste liquid after the semiconductor wafer is cleaned, it is preferred to use a preservative. In order to clean the semiconductor wafer, a large amount of washing water is generally used. However, in the process using the protective film forming agent, there is concern about the growth of miscellaneous bacteria in the waste liquid caused by the water-soluble resin (A) contained in the protective film forming agent. Therefore, it is desirable to separate the waste liquid from the process using the protective film forming agent from the waste liquid from the process not using the protective film forming agent. However, in the case where the protective film forming agent contains a preservative, since the growth of miscellaneous bacteria caused by the water-soluble resin (A) is suppressed, the waste liquid from the process using the protective film forming agent can be treated in the same manner as the waste liquid from the process not using the protective film forming agent. Therefore, the load of the wastewater treatment process can be reduced.

[0117] The surfactant can be used, for example, to improve the defoaming property during the production of the protective film forming agent, the stability of the protective film forming agent, the coating property of the protective film forming agent, etc. In particular, it is preferable to use a surfactant in terms of the defoaming property during the production of the protective film forming agent.

[0118] Generally, the protective film is formed by spin coating a protective film forming agent. However, when forming the protective film, bumps and depressions caused by bubbles may sometimes occur. In order to suppress the generation of such bumps and depressions, a defoaming agent such as a surfactant is preferably used.

[0119] As the surfactant, a water-soluble surfactant can be preferably used. As the surfactant, any one of a nonionic surfactant, a cationic surfactant, an anionic surfactant and an amphoteric surfactant can be used. The surfactant may also be silicone-based. From the viewpoint of cleaning properties, a nonionic surfactant is preferred.

[0120] <Solvent (S)>

[0121] The protective film forming agent contains a solvent (S) in order to dissolve the water-soluble resin (A), the light absorber (B) or the alkaline compound (C). As the solvent (S), any one of water, an organic solvent and an aqueous solution of an organic solvent can be used. From the perspective of less risk of flash fire during use or from the perspective of cost, the solvent (S) is preferably water or an aqueous solution of an organic solvent, and more preferably water.

[0122] From the viewpoint of flash flammability, the content of the organic solvent in the solvent (S) is preferably 20 mass % or less, more preferably 15 mass % or less, further preferably 10 mass % or less, further preferably 5 mass % or less, particularly preferably 3 mass % or less.

[0123] The solvent (S) is preferably selected so that the protective film forming agent does not have a flash point at 1 atmosphere. Specifically, the flash point of the protective film or the presence or absence of the flash point is adjusted by adjusting the water content in the protective film forming agent.

[0124] The protective film forming agent without a flash point is safe, for example, it can be used in a non-explosion-proof environment. Specifically, the protective film forming agent can be stored, transported, used, etc. in a non-explosion-proof environment. For example, not only can the protective film forming agent be introduced into a semiconductor factory, but also the protective film can be formed in a non-explosion-proof environment. Therefore, the protective film forming agent without a flash point is very advantageous in industry in that it does not require an explosion-proof environment such as an explosion-proof equipment which is usually expensive.

[0125] The flash point is obtained by measuring with a Tag closed-cup tester at 1 atmosphere and a liquid temperature of 80°C or less, and by measuring with a Cleveland open-cup tester at a liquid temperature of more than 80°C.

[0126] In this specification, the case where the flash point cannot be measured even by the Cleveland opening method is regarded as no flash point.

[0127] Examples of the organic solvent that may be contained in the protective film forming agent include methanol, ethanol, alkylene glycol, alkylene glycol monoalkyl ether, and alkylene glycol monoalkyl ether acetate.

[0128] Examples of the alkylene glycol include ethylene glycol and propylene glycol. Examples of the alkylene glycol monoalkyl ether include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether and propylene glycol monoethyl ether. Examples of the alkylene glycol monoalkyl ether acetate include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate.

[0129] The protective film forming agent may contain two or more organic solvents in combination.

[0130] The solid content concentration of the protective film forming agent is not particularly limited within a range not hindering the purpose of the present invention. The solid content concentration is, for example, preferably 5 mass % to 60 mass %, more preferably 10 mass % to 50 mass %.

[0131] Semiconductor chip manufacturing method

[0132] The method for manufacturing a semiconductor chip is a method for manufacturing a semiconductor chip by processing a semiconductor wafer.

[0133] More specifically, the method for manufacturing a semiconductor chip includes:

[0134] Applying the protective film forming agent on the semiconductor wafer to form a protective film;

[0135] Laser light is irradiated onto predetermined positions of one or more layers including a protective film on a semiconductor wafer to expose the surface of the semiconductor wafer and form a processing groove having a pattern corresponding to the shape of the semiconductor chip.

[0136] Typically, the method for manufacturing the semiconductor chip includes a cutting step of cutting blocks in the semiconductor wafer.

[0137] Hereinafter, forming a protective film is also described as a “protective film forming step”, forming a processing groove is also described as a “processing groove forming step”, and cutting the positions of blocks in a semiconductor wafer is also described as a “cutting step”.

[0138] <Protective Film Formation Step>

[0139] In the protective film forming step, the protective film forming agent is applied on the semiconductor wafer to form a protective film.

[0140] The shape of the processed surface of the semiconductor wafer is not particularly limited as long as the desired processing can be performed on the semiconductor wafer. Typically, the processed surface of the semiconductor wafer has a large number of irregularities. In addition, a concave portion is formed in an area corresponding to a street block.

[0141] The processing surface of a semiconductor wafer is divided into a plurality of areas corresponding to semiconductor chips by blocks.

[0142] From the viewpoint of facilitating the removal of the protective film by water washing after processing, or from the viewpoint of sufficient durability of the protective film against plasma irradiation when plasma irradiation is performed in the cutting step described later, the film thickness of the protective film is typically preferably 1 μm to 100 μm, more preferably 10 μm to 100 μm, and further preferably 30 μm to 100 μm.

[0143] When laser irradiation is performed in the machining groove forming step and / or the cutting step, the film thickness of the protective film is preferably 0.1 μm or more and 10 μm or less.

[0144] In the cutting step, when the cutting is performed with a cutter, the thickness of the protective film is not particularly limited. When the cutting is performed with a cutter, the thickness of the protective film is preferably 0.1 μm to 100 μm, for example, because the protective film can be easily removed by washing after processing.

[0145] Hereinafter, a method for manufacturing semiconductor chips, which includes dicing a semiconductor wafer having a plurality of semiconductor chips divided into grid-like blocks using the protective film agent, will be described as a preferred embodiment of the method for manufacturing semiconductor chips with reference to the drawings.

[0146] exist Figure 1A three-dimensional diagram showing a semiconductor wafer to be processed. Figure 2 Show Figure 1 The main part of the semiconductor wafer is enlarged and sectional. Figure 1 and Figure 2 In the semiconductor wafer 2 shown, a stacked body 21 in which an insulating film and a functional film forming a circuit are stacked is provided on a surface 20a of a semiconductor substrate 20 such as silicon. In the stacked body 21, a plurality of semiconductor chips 22 such as ICs and LSIs are formed in a matrix.

[0147] Here, the shape and size of the semiconductor chip 22 are not particularly limited and can be appropriately set according to the design of the semiconductor chip 22 .

[0148] Each semiconductor chip 22 is divided by a grid-shaped block 23. In the illustrated embodiment, the insulating film used as the laminate 21 is made of SiO 2 The low dielectric constant insulator coating (Low-k film) is composed of a film, or an inorganic film such as SiOF, BSG (SiOB), or an organic film such as a polymer film such as a polyimide, polyparaxylene, etc.

[0149] The surface of the laminate 21 corresponds to the surface 2a as a processed surface. On the surface 2a, a protective film is formed using the protective film forming agent.

[0150] In the protective film forming step, the protective film is formed by applying the protective film forming agent to the surface 2a of the semiconductor wafer 2 using, for example, a spin coater. The method for applying the protective film forming agent is not particularly limited as long as a protective film having a desired film thickness can be formed.

[0151] Next, the liquid protective film forming agent covering the surface 2a is dried. Figure 3 As shown, a protection film 24 is formed on the surface 2 a of the semiconductor wafer 2 .

[0152] In this way, after the protective film 24 is formed on the surface 2a of the semiconductor wafer 2, Figure 4 As shown, a protective tape 6 attached to a ring-shaped frame 5 is attached to the back surface of the semiconductor wafer 2 .

[0153] <Processing Groove Forming Step>

[0154] In the machining groove forming step, laser light is irradiated to predetermined positions of one or more layers including the protective film 24 on the semiconductor wafer 2 to expose the surface 20 a of the semiconductor substrate 20 and form machining grooves having a pattern corresponding to the shape of the semiconductor chip 22 .

[0155] Specifically, the laser processing device 7 is used to irradiate the surface 2a (block 23) on the semiconductor wafer 2 through the protective film 24 with laser. Figure 5 As shown, the laser beam irradiation mechanism 72 is used to implement the laser irradiation.

[0156] From the viewpoint of intensity, the laser is preferably an ultraviolet laser having a wavelength of 100 nm to 400 nm, and preferably a YVO4 laser or a YAG laser having a wavelength of 266 nm, 355 nm, or the like.

[0157] The laser irradiation in the processed groove forming step is performed, for example, under the following processing conditions: The focal spot diameter is appropriately selected in consideration of the width of the processed groove 25 .

[0158] Laser light source: YVO4 laser or YAG laser

[0159] Wavelength: 355nm

[0160] Repetition frequency: 50kHz or more and 100kHz or less

[0161] Output: 0.3W or more, 4.0W or less

[0162] Processing feed speed: 1mm / s to 800mm / s

[0163] By implementing the above-mentioned processing groove forming process, Figure 6 As shown, in the stacked body 21 having the block 23 in the semiconductor wafer 2, the processed groove 25 is formed along the block 23. In the case of forming the protective film 24 from the protective film forming agent, since the protective film 24 has excellent laser processability, that is, excellent decomposition and removal properties by laser, it is possible to easily form a groove of a desired shape in the protective film 24 by irradiating the protective film 24 with laser as described above.

[0164] As described above, laser irradiation is performed along the predetermined blocks 23, and then the semiconductor wafer 2 held by the chuck table 71 is indexed and moved in the direction indicated by the arrow Y at intervals of the blocks, and laser irradiation is performed again.

[0165] After all the blocks 23 extending in the specified direction are irradiated with laser light and indexed, the semiconductor wafer 2 held by the chuck table 71 is rotated 90 degrees, and the laser light is irradiated and indexed in the same manner as above along each block 23 extending at a right angle to the specified direction. In this way, the processing grooves 25 can be formed along all the blocks 23 of the stacked body 21 formed on the semiconductor wafer 2.

[0166] <Cutting process>

[0167] In the cutting process, the semiconductor wafer 2 having the processed groove 25 is cut at a position corresponding to the position of the block 23. As a preferred method, there can be mentioned a method of cutting the semiconductor wafer 2 by irradiating the semiconductor wafer 2 having the protective film 24 and the processed groove 25 with laser or plasma, and a method of cutting the semiconductor wafer 2 having the protective film 24 or the semiconductor wafer 2 from which the protective film 24 is peeled off with a cutter. In the case of irradiating with laser, the processed groove 25 is irradiated with laser in order to cut the semiconductor wafer 2. In the case of irradiating with plasma, plasma is irradiated to a part or the entire surface of the surface having the protective film of the semiconductor wafer 2 in such a manner that plasma is exposed to the surface of the processed groove 25. In the case of cutting with a cutter, the semiconductor wafer 2 is cut along the position of the processed groove 25 with the cutter while supplying pure water to the cutting portion.

[0168] Hereinafter, a cutting method using plasma irradiation will be described as a preferred cutting method.

[0169] like Figure 7 As shown in FIG. 2 , the semiconductor wafer 2 having the protective film 24 and the processed groove 25 is irradiated with plasma. Figure 8 As shown, the position of the processing groove 25 in the semiconductor wafer 2 is cut.

[0170] Specifically, in the semiconductor wafer 2 covered with the protective film 24, as described above, after the processing groove 25 is formed, the protective film 24 and the surface 20a of the semiconductor substrate 20 exposed from the processing groove 25 are plasma irradiated, thereby cutting the semiconductor wafer 2 into the shape of the semiconductor chip 22, and the semiconductor wafer 2 is divided into semiconductor chips 22.

[0171] The plasma irradiation conditions are not particularly limited as long as the semiconductor wafer 2 can be cut satisfactorily at the position of the processed groove 25. The plasma irradiation conditions are appropriately set within the range of general conditions for plasma etching of semiconductor substrates in consideration of the material of the semiconductor wafer 2 and the type of plasma.

[0172] The gas used to generate plasma during plasma irradiation can be appropriately selected according to the material of the semiconductor wafer 2. Typically, SF 6 gas.

[0173] Furthermore, according to the so-called BOSCH process, by alternately utilizing C 4 F 6 or C 4 F 8The sidewall protection by supplying gas or the like and the etching of the semiconductor wafer 2 by plasma irradiation can also be used to cut the semiconductor wafer 2. According to the BOSCH process, etching can be performed at a high aspect ratio, and the semiconductor wafer 2 can be easily cut even when the semiconductor wafer 2 is thick.

[0174] Then, if Fig. 9 As shown, the protective film 24 covering the surface of the semiconductor chip 22 is removed. As described above, the protective film 24 is formed using the protective film forming agent containing the water-soluble resin (A), so the protective film 24 can be washed away with water (or warm water).

[0175] The above is a description of a method for manufacturing a semiconductor chip by processing a semiconductor wafer based on an embodiment. The protective film forming agent and the method for manufacturing a semiconductor chip of the present invention can be applied to various methods for manufacturing semiconductor chips as long as the method includes forming a protective film on the surface of a semiconductor wafer and forming a processing groove at a position corresponding to a block in the surface of the semiconductor wafer having the protective film.

[0176] Example

[0177] The present invention is specifically described below by way of examples and comparative examples, but the present invention is not limited in any way by the following examples.

[0178] [Examples 1 to 15 and Comparative Examples 1 to 12]

[0179] In Examples 1 to 15 and Comparative Examples 1 to 12, hydroxypropyl cellulose (A1) and polyvinyl pyrrolidone (A2) were used as the water-soluble resin (A).

[0180] Furthermore, B1 to B4 represented by the following formulae were used as the light absorber (B).

[0181] [Chemistry 7]

[0182]

[0183] In addition, monoethanolamine (C1), diethanolamine (C2), triethanolamine (C3), imidazole (C4), ammonia (C5), and NaOH (C6) were used as the basic compound (C).

[0184] In addition, water (S1) and propylene glycol monomethyl ether (PGME) (S2) were used as the solvent (S).

[0185] (Manufacture of protective film forming agent)

[0186] The types and amounts of water-soluble resin (A), light absorber (B), basic compound (C) and solvent (S) described in Tables 1 to 3 were respectively placed in a container and stirred for 8 hours to obtain protective film forming agents of each example and comparative example. In addition, the units of the numerical values ​​(amounts) of the blending in Tables 1 to 3 are mass %.

[0187] (Evaluation of Solubility of Light Absorber)

[0188] The obtained protective film forming agent was visually observed and evaluated according to the evaluation criteria described below. The results are shown in Tables 1 to 3.

[0189] <Evaluation Criteria for Solubility of Light Absorbent>

[0190] ○: No dissolved light absorber remains.

[0191] ×: There are dissolved residues of the light absorber.

[0192] (Measurement of absorbance of protective film (coating film))

[0193] Using the obtained protective film forming agent, a protective film was formed on a glass substrate by spin coating (spin coating conditions: 2000 rpm, 120 seconds).

[0194] The formed protective film was measured for transmittance using a spectrophotometer (MCPD-3000 (manufactured by Otsuka Electronics)), and the absorbance per 1 μm film thickness at a wavelength of 355 nm was measured based on the transmittance measurement results. The measurement results are shown in Tables 1 to 3. In addition, the absorbance was not measured for the protective film forming agent in which the dissolved residue of the light absorber was observed.

[0195] (Evaluation of laser processability)

[0196] The obtained protective film forming agent was applied on a silicon substrate by a spin coating method so as to have a film thickness of 2 μm, thereby forming a protective film.

[0197] For the surface on the protective film side of the silicon substrate with a protective film, laser irradiation is performed in a straight line under the following conditions. Then, the protective film is removed, and the laser irradiated part (processing part) and its vicinity are observed using an optical microscope, and evaluated according to the evaluation criteria described below. If the laser processability is poor, it is difficult to decompose and remove the protective film, and the protective film is not decomposed and removed but peeled off from the substrate in the state of a film, and the substrate debris is attached to the peeled part. Therefore, the laser processability can be evaluated by observing the processed part and its vicinity after the protective film is removed.

[0198] <Laser irradiation conditions>

[0199] Wavelength: 355nm

[0200] Frequency: 100kHz

[0201] Output: 0.8W

[0202] Defocus: -0.0mm

[0203] Feed speed: 100mm / s

[0204] Pass: 1

[0205] <Cross-sectional shape evaluation criteria>

[0206] ○: Adhesion of chips was not observed on the outer side of the processed portion.

[0207] ×: Adhesion of chips was observed on the outer side of the processed portion.

[0208] [Table 1]

[0209]

[0210] [Table 2]

[0211]

[0212] [Table 3]

[0213]

[0214] According to Tables 1 to 3, the protective film forming agents of Examples 1 to 14, which contain a water-soluble resin (A), a light absorber (B), a basic compound (C) and a solvent (S), have excellent solubility of the light absorber. In addition, it is known that the protective films formed using the protective film forming agents of Examples 1 to 14 have high absorbance and excellent laser processability.

[0215] On the other hand, as can be seen from Tables 1 to 3, the protective film forming agents of Comparative Examples 1 to 12 not containing the basic compound (C) have poor solubility of the light absorber and poor laser processability of the protective film.

[0216] Description of Reference Numerals

[0217] 2 Semiconductor Wafers

[0218] 20 substrate

[0219] 21 Laminated body

[0220] 22 Semiconductor Chip

[0221] 23 Blocks

[0222] 24 Protective film

[0223] 25 Laser Processing Slots

[0224] 26 Cutting groove

[0225] 3 Spin coater

[0226] 5 Ring frame

[0227] 6 Protective tape

[0228] 7 Laser processing equipment

[0229] 71 Chuck table for laser processing device

[0230] 72. Laser beam irradiation mechanism.

Claims

1. A protective film forming agent used to form a protective film on the surface of a semiconductor wafer during dicing of the semiconductor wafer, characterized in that: It comprises a water-soluble resin (A), a light absorber (B), a basic compound (C) and a solvent (S), The water-soluble resin (A) is hydroxypropyl cellulose or polyvinyl pyrrolidone, The light absorber (B) is a compound represented by the following formula (B1-1) or a compound represented by the following formula (B2), [Chemistry 1] In formula (B1-1), R 1 and R 3 are independently hydroxyl or carboxyl, R 2 and R 4 are independently hydroxyl, carboxyl or -NR 5 R 6 The group represented by R 5 and R 6 are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, m and n are each independently an integer of 0 to 2, [Chemistry 2] In formula (B2), R 11 For -NR 12 R 13 The group represented by R 12 and R 13 are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, p is an integer of 0 to 3, and when p is 2 or more, a plurality of R 11 Can be the same or different.

2. The protective film forming agent according to claim 1, characterized in that The basic compound (C) includes at least one selected from alkylamines, alkanolamines, imidazole compounds, ammonia, and hydroxides of alkali metals.

3. The protective film forming agent according to claim 1, characterized in that The light absorber (B) is a benzophenone compound represented by the following formula B1 and B2 or a cinnamic acid compound represented by the following formula B3, [Chemistry 3] 4. The protective film forming agent according to claim 1, characterized in that The content of the light absorber (B) is 0.1 mass % to 10 mass %.

5. The protective film forming agent according to claim 1, characterized in that The solvent (S) comprises water.

6. The protective film forming agent according to any one of claims 1 to 5, characterized in that The content of the organic solvent in the solvent (S) is 20% by mass or less.

7. A method for manufacturing a semiconductor chip, processing a semiconductor wafer, characterized in that: include: Applying the protective film forming agent according to any one of claims 1 to 6 on the semiconductor wafer to form a protective film; Predetermined positions of one or more layers including the protective film on the semiconductor wafer are irradiated with laser light to expose the surface of the semiconductor wafer and form processing grooves in a pattern corresponding to the shape of the semiconductor chip.

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