Protective film forming agent, protective film, method for manufacturing protective film and method for manufacturing semiconductor chip

Abstract

To provide a protective film forming agent capable of producing a protective film having excellent film forming properties and a high selectivity ratio, as well as a protective film obtained by such the protective film forming agent, a method for manufacturing the protective film, and a method for manufacturing a semiconductor chip.SOLUTION: A protective film forming agent containing a metal salt of tin, a first resin without an aromatic ring, and a solvent, and a protective film obtained by the protective film forming agent, a method for manufacturing the protective film and a method for manufacturing a semiconductor chip are provided.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a protective film forming agent, a protective film, a method for manufacturing the protective film, and a method for manufacturing a semiconductor chip.

Background Art

[0002] A wafer formed in a semiconductor device manufacturing process is a laminate in which an insulating film and a functional film are laminated on the surface of a semiconductor substrate such as a silicon substrate, and is partitioned by a lattice-shaped division planned line called a street. By cutting the wafer along this street, a plurality of semiconductor chips can be obtained (chip separation). That is, each region partitioned by the street becomes a semiconductor chip such as an IC or an LCI.

[0003] By cutting the wafer along this street, a plurality of semiconductor chips can be obtained. For example, in an optical device wafer, a laminate in which a gallium nitride-based compound semiconductor or the like is laminated is partitioned into a plurality of regions by a street. By cutting along this street, the optical device wafer is divided into optical devices such as light emitting diodes and laser diodes. These optical devices are widely used in electric devices.

[0004] Such wafer cutting is performed, for example, by plasma dicing. Plasma dicing is a processing technique for cutting a wafer into chips by performing dry etching under vacuum or reduced pressure. In plasma dicing, for example, a Bosch process or the like capable of deep etching of the wafer is used.

[0005] Patent Document 1 discloses a method of dicing a substrate including a plurality of ICs, the method including: forming a mask that covers and protects the ICs on the substrate, the mask including a layer of a water-soluble material that contacts the upper surface of the ICs; patterning the mask by a laser scribing process to provide a patterned mask having gaps and exposing regions of the substrate between the ICs; and plasma etching the substrate through the gaps in the patterned mask to singulate the ICs.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] When dicing a wafer by plasma dicing, in order to protect the wafer, a protective film is provided on the surface of the wafer. The protective film, for example, prevents impurities such as cut debris and other particles generated during dicing from adhering to the surface of the wafer, but there is still room for improvement in the performance of the protective film.

[0008] Normally, the protective film is formed by applying a protective film forming agent to the wafer and forming a film. However, if cracks occur in the protective film, impurities such as cut debris and other particles will adhere to the wafer, contaminating the wafer or damaging the wafer. Also, when performing plasma dicing on a device with steps, the thickness of the protective film cannot be ensured sufficiently at the upper part of the steps, and it may be unintentionally thinned. For these reasons, the protective film forming agent is required to have excellent film-forming properties capable of suppressing the occurrence of cracks.

[0009] In plasma dicing, a wafer is etched using an etching gas such as a fluorine-based gas. At this time, radicals generated from such an etching gas (for example, fluorine radicals generated from a fluorine-based gas) may etch or damage the wafer unnecessarily. When such unintentional etching occurs, the film thickness of the protective film will decrease. For this reason, the protective film forming agent is required to have a high selectivity between the protective film and the film to be etched.

[0010] The present invention has been made in view of the above circumstances, and the main object thereof is to provide a protective film forming agent capable of producing a protective film having excellent film-forming properties and a high selectivity, a protective film obtained by such a protective film forming agent, a method for manufacturing the protective film, and a method for manufacturing a semiconductor chip.

Means for Solving the Problems

[0011] As a result of intensive studies to achieve the above-described object, the present inventors have surprisingly found that a protective film forming agent containing a metal salt of tin, a first resin having no aromatic ring, and a solvent, and have completed the present invention.

[0012] That is, the present invention is as follows. <1> A protective film forming agent containing a metal salt of tin, a first resin having no aromatic ring, and a solvent. <2> The protective film forming agent according to <1>, further containing a second resin having an aromatic ring. <3> The protective film forming agent according to <1> or <2>, wherein the content ratio of tin in the metal salt in the total amount of the components excluding the solvent from the protective film forming agent is 500 mass ppb or more. <4> The protective film forming agent according to any one of <1> to <3>, wherein the metal salt contains at least one selected from the group consisting of sulfates, nitrates, nitrites, and hydrates thereof. <5> The protective film forming agent according to any one of <1> to <4>, wherein the first resin contains at least one selected from the group consisting of a cellulose-based resin and a vinyl-based resin. <6> The protective film forming agent according to any one of <1> to <5>, wherein the first resin contains at least one selected from the group consisting of a resin (1A) containing a repeating unit represented by the following formula (1a), a resin (1B) containing a repeating unit represented by the following formula (1b-1) and a repeating unit represented by the following formula (1b-2), a resin (1C) containing a repeating unit represented by the following formula (1c), and a resin (1D) containing a repeating unit represented by the following formula (1d).

[0013]

Chemical formula

[0014] (In the formula, R 1 , R 2 , and R 3 are each independently a substituent represented by -H, -CH3, -CH2CH3, or -CH2CH(OH)CH3, and at least one of all R 1 , R 2 , and R 3 is a substituent other than -H.)

[0015]

Chemical formula

[0016]

Chemical formula

[0017]

Chemical formula

[0018] <7> The second resin is at least one selected from the group consisting of a resin (2A) containing a repeating unit represented by the following formula (2a-1) and a repeating unit represented by the following formula (2a-2), a resin (2B) containing a repeating unit represented by the following formula (2b-1) and a repeating unit represented by the following formula (2b-2), and a resin (2C) containing a repeating unit represented by the following formula (2c), and is the protective film forming agent according to any one of <2> to <6>.

[0019]

Chemical formula

[0020] (In the formula, X + is an alkali metal cation, a proton, or N + R 4 4, and R 4 is a hydrogen atom, an alkyl group, or a hydroxyalkyl group.)

[0021]

Chemical formula

[0022] (In the formula, M 1+ and M 2+ are each independently an alkali metal cation, a proton, or N + R 5 4, and R 5 is a hydrogen atom, an alkyl group, or a hydroxyalkyl group.)

[0023]

Chemical formula

[0024] <8> The protective film contains a metal salt of tin and a first resin having no aromatic ring. <9> Furthermore, the protective film according to <8> contains a second resin having an aromatic ring. <10> The protective film according to <8> or <9>, wherein the content of tin in the metal salt in the protective film is 500 mass ppb or more. <11> The protective film according to any one of <8> to <10>, wherein the film thickness is 0.1 μm or more and 100 μm or less. <12> A method for manufacturing a protective film, comprising a step of applying a protective film forming agent according to any one of <1> to <7> on a substrate to form a protective film. <13> A method for manufacturing a semiconductor chip, which cuts a semiconductor wafer by plasma dicing, comprising a step of applying a protective film forming agent according to any one of <1> to <7> on the semiconductor wafer to form a protective film, a step of irradiating laser light to a predetermined position of one or more layers including the protective film on the semiconductor wafer to expose the surface of the semiconductor wafer and form a processing groove having a pattern according to the shape of the semiconductor chip, and a step of irradiating plasma to the semiconductor wafer on which the processing groove is formed to cut the position of the processing groove of the semiconductor wafer to obtain a semiconductor chip.

Advantages of the Invention

[0025] According to the present invention, it is possible to provide a protective film forming agent capable of producing a protective film excellent in film forming property and having a high selectivity ratio, a protective film obtained by such a protective film forming agent, a method for manufacturing a protective film, and a method for manufacturing a semiconductor chip.

Embodiments for Carrying Out the Invention

[0026] Hereinafter, embodiments 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 exemplification for explaining the present invention and is not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of its gist.

[0027] <Protective Film Forming Agent>

[0028] The protective film forming agent according to this embodiment is a protective film forming agent containing a metal salt of tin, a first resin having no aromatic ring, and a solvent. The protective film forming agent can be used, for example, to form a protective film on the surface of a semiconductor wafer when dicing the semiconductor wafer. As a result of intensive research by the present inventors, unexpectedly, by using a resin having no aromatic ring and a metal salt of tin in combination, a protective film excellent in film forming properties and selectivity can be obtained.

[0029] (Metal salt of tin)

[0030] The protective film forming agent according to this embodiment contains a metal salt of tin. The metal salt of tin may be present as tin ions in the protective film forming agent. The type of salt is not particularly limited, but from the viewpoints of film forming properties and selectivity, it preferably contains at least one selected from the group consisting of sulfates, nitrates, nitrites, and hydrates thereof. Since these salts tend to have high water solubility, the compatibility with other components in the protective film forming agent is further enhanced, and the film forming properties and selectivity can be further improved.

[0031] The tin content is not particularly limited, but from the viewpoint of having excellent film forming properties and further increasing the selectivity, the content ratio of tin in the metal salt in the total amount of the components excluding the solvent from the protective film forming agent ((tin) / (total amount of the components excluding the solvent from the protective film forming agent)) is preferably 500 mass ppb or more. The lower limit of this content ratio is more preferably 600 mass ppb or more, still more preferably 700 mass ppb or more, even more preferably 750 mass ppb or more, and still even more preferably 800 mass ppb or more. The upper limit of this content ratio is more preferably 1000 mass ppb or less, still more preferably 950 mass ppb or less, and even more preferably 900 mass ppb or less. Note that when the tin is present as tin ions in the protective film forming agent, the tin ions are also included in the tin content.

[0032] Regarding the metal species of the metal salt, from the viewpoint of further achieving both high film-forming properties and high selectivity in the protective film-forming agent according to the present embodiment, the content of metal ions other than tin is preferably low, and it is preferably substantially not contained. For example, the content of metal ions of Li, Be, Na, Mg, Al, K, Ca, Mn, Fe, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Ag, Cd, In, Cs, Ba, La, and Ce is preferably 100 ppb by mass or less, more preferably 50 ppb by mass or less, and still more preferably 0% by mass. Further, it is even more preferable that these metal ions other than tin are substantially not contained. Note that "substantially not contained" in the present specification means that the component is not actively added or mixed, and does not exclude the case where it is unavoidably contained or mixed.

[0033] (First resin)

[0034] The first resin is a resin having no aromatic ring (sometimes referred to as a "non-aromatic resin"). The first resin is preferably water-soluble (sometimes referred to as a "water-soluble resin"). If it is water-soluble, 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. Further, after plasma etching, the protective film can be easily removed by washing with water. Note that "water-soluble" in the present specification means that 0.5 g or more of the solute (the resin) dissolves in 100 g of water at 25°C.

[0035] In this regard, conventionally, when a protective film is formed using a water-soluble material, there is a problem that cracks are likely to occur. In particular, when the protective film is thick, cracks tend to occur. Further, when a water-soluble material is used, the selectivity tends to decrease. However, according to the present embodiment, surprisingly, by using the above-described metal salt and the first resin in combination, such problems can be effectively suppressed.

[0036] Note that the water-soluble resin also includes a resin solubilized in water by a hydrolysis reaction or treatment with a base in an aqueous medium. For example, as a result of such a reaction or treatment, a resin in which 0.5 g or more of the solute (the resin) can be dissolved in 100 g of water at 25°C also corresponds to the "water-soluble resin" referred to in this specification.

[0037] The first resin preferably contains at least one selected from the group consisting of a cellulose-based resin, a vinyl-based resin, a polyalkylene oxide (for example, polyethylene oxide such as polyethylene glycol, polypropylene oxide such as polypropylene glycol, etc.), polyglycerin, and water-soluble nylon, and more preferably contains at least one selected from the group consisting of a cellulose-based resin and a vinyl-based resin. These are preferably water-soluble.

[0038] The weight average molecular weight of the first resin is not particularly limited, but is usually preferably 100 or more and 300,000 or less. The lower limit of this weight average molecular weight is more preferably 1,000 or more, and even more preferably 10,000 or more. Also, the upper limit of this weight average molecular weight is more preferably 200,000 or less, and even more preferably 150,000 or less.

[0039] Note that unless otherwise specified, the weight average molecular weight in this specification refers to the polystyrene-equivalent weight average molecular weight (M w ) obtained by gel permeation chromatography (GPC) analysis.

[0040] The cellulose-based resin is cellulose or a cellulose derivative, and preferably has water solubility. Examples of the cellulose derivative include those obtained by modifying cellulose with an alkyl group (such as a methyl group or an ethyl group), and those obtained by modifying cellulose with a hydroxyalkyl group (such as a hydroxymethyl group, a hydroxyethyl group, or a hydroxypropyl group). 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.

[0041] The weight average molecular weight of the cellulose-based resin is not particularly limited, but is preferably 1000 or more and 300000 or less. The lower limit of this weight average molecular weight is more preferably 10000 or more. Also, the upper limit of this weight average molecular weight is more preferably 200000 or less, and even more preferably 150000 or less.

[0042] The vinyl-based resin is a homopolymer of a monomer having a vinyl group or a copolymer of a monomer having a vinyl group, and is preferably a water-soluble resin. Specific examples of the vinyl-based resin include at least one selected from the group consisting of polyvinyl alcohol-based resins, poly-N-vinylacetamide, polyvinylpyrrolidone, polyacrylamide, poly(N-alkylacrylamide), polyallylamine, poly(N-alkylallylamine), partially amidated polyallylamine, poly(diallylamine), allylamine·diallylamine copolymer, and polyacrylic acid.

[0043] Specific examples of the polyvinyl alcohol-based resin include polyvinyl alcohol, polyvinyl acetal (including vinyl acetate copolymer), butanediol·vinyl alcohol copolymer, polyvinyl alcohol-polyacrylic acid block copolymer, polyvinyl alcohol-polyacrylic acid ester block copolymer, etc. Among these, polyvinyl alcohol is preferred.

[0044] The protective film formed on the surface of the semiconductor wafer is usually removed from the surface of the semiconductor wafer or semiconductor chip by water washing at an appropriate time after the formation of the processing grooves. Therefore, from the viewpoint of the water washability of the protective film, it is preferably a water-soluble resin having a high affinity for water. Among the above-described resins, examples of the water-soluble resin having a high affinity for water include resins having only a hydroxyl group, an amide bond, and / or an ether bond as polar groups, such as hydroxypropyl cellulose, polyvinyl alcohol, poly-N-vinylacetamide, polyvinylpyrrolidone, polyethylene glycol, and the like.

[0045] Furthermore, from the viewpoint that it can be expected to more effectively suppress the deterioration of the shape of the processing grooves due to heat sagging of the protective film, etc., cellulose-based resins and vinyl-based resins are preferred, and hydroxypropyl cellulose, polyvinyl alcohol, poly-N-vinylacetamide, polyvinylpyrrolidone, etc. are more preferred.

[0046] These may be used alone or in combination of two or more.

[0047] A more specific preferred example of the first resin will be described. The first resin preferably contains at least one selected from the group consisting of a resin (1A) containing a repeating unit represented by the following formula (1a), a resin (1B) containing a repeating unit represented by the following formula (1b-1) and a repeating unit represented by the following formula (1b-2), a resin (1C) containing a repeating unit represented by the following formula (1c), and a resin (1D) containing a repeating unit represented by the following formula (1d).

[0048]

Chemical formula

[0049] (In the formula, R 1 , R 2 , and R 3 are each independently a substituent represented by -H, -CH3, -CH2CH3, or -CH2CH(OH)CH3, and all R 1 , R2 and R 3 Among them, at least one is a substituent other than -H.)

[0050] [Chemical formula]

[0051] [Chemical formula]

[0052] [Chemical formula]

[0053] The resin (1A) may be a resin containing a repeating unit represented by the formula (1a), and may also have other repeating units. From the viewpoints of the film-forming property of the protective film, the selectivity ratio, the water washability, the precision of the shape of the processing groove, etc., the resin (1A) is preferably a resin having only the repeating unit represented by the formula (1a). Specific examples of the resin (1A) include cellulose derivatives. Preferable examples of the resin (1A) include the above-mentioned methyl cellulose, ethyl cellulose, and propylene cellulose, etc.

[0054] R in the formula (1a) 1 , R 2 , and R 3 may each independently be a substituent represented by -H, -CH3, -CH2CH3, or -CH2CH(OH)CH3, but R 1 , R 2 , and R 3 are each independently a substituent represented by -H or -CH2CH(OH)CH3, and at least one of all R 1 , R 2 , and R 3 is preferably -CH2CH(OH)CH3.

[0055] The weight average molecular weight of the resin (1A) is not particularly limited, but is preferably 10,000 or more and 300,000 or less. The lower limit of the weight average molecular weight is more preferably 15,000 or more, and still more preferably 20,000 or more. Also, the upper limit of the weight average molecular weight is more preferably 200,000 or less, still more preferably 100,000 or less, and even more preferably 50,000 or less.

[0056] The resin (1B) may be a resin containing a repeating unit represented by the formula (1b-1) and a repeating unit represented by the formula (1b-2) (see formula (1b)), and may also contain other repeating units. From the viewpoints of the film-forming property, the selectivity ratio, the water washability, the precision of the shape of the processing groove, etc. of the protective film, the resin (1B) is preferably a resin having only the repeating unit represented by the formula (1b-1) and the repeating unit represented by the formula (1b-2) (see formula (1b)).

[0057] The water solubility of the resin (1B) can be improved, for example, by adjusting the content of the repeating unit represented by the formula (1b-1), the content of the repeating unit represented by the formula (1b-2), and the molar ratio of the repeating unit represented by the formula (1b-1) to the repeating unit represented by the formula (1b-2).

[0058] The ratio of the repeating unit represented by the formula (1b-1) and the repeating unit represented by the formula (1b-2) is not particularly limited, but from the above viewpoints, in the total of the repeating unit represented by the formula (1b-1) and the repeating unit represented by the formula (1b-2), the upper limit of the molar ratio of the repeating unit represented by the formula (1b-1) (formula (1b-1) / (formula (1b-1)+formula (1b-2))) is preferably 0.965 or less, and preferably 0.890 or less. The lower limit of this molar ratio is not particularly limited, but is preferably 0.500 or more, and more preferably 0.695 or more.

[0059] Preferable examples of the resin (1B) include the above-described polyvinyl alcohol and the like. Polyvinyl alcohol can be obtained, for example, by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate monomer. In that case, as represented by formula (1b), a resin having both a repeating unit represented by formula (1b-1) and a repeating unit represented by formula (1b-2) can be obtained.

[0060] The degree of polymerization of the resin (1B) is not particularly limited, but is preferably 300 or more and 2500 or less. The lower limit of the degree of polymerization is more preferably 500 or more. Also, the upper limit of the degree of polymerization is more preferably 2000 or less.

[0061] The resin (1C) may be any resin containing a repeating unit represented by formula (1c), and may also contain other repeating units. From the viewpoints of film-forming property of the protective film, selectivity ratio, water washability, precision of the shape of the processing groove, etc., the resin (1C) is preferably a resin having only the repeating unit represented by formula (1c). Preferable examples of the resin (1C) include the above-described poly-N-vinylacetamide and the like.

[0062] The weight average molecular weight of the resin (1C) is not particularly limited, but is preferably 200,000 or more and 1,500,000 or less. The lower limit of the weight average molecular weight is more preferably 250,000 or more, and even more preferably 500,000 or more. Also, from the viewpoint of film-forming property and the like, the upper limit of the weight average molecular weight is more preferably 1,000,000 or less.

[0063] The resin (1D) may be any resin containing a repeating unit represented by formula (1d), and may also have other repeating units. From the viewpoints of film-forming property of the protective film, selectivity ratio, water washability, precision of the shape of the processing groove, etc., the resin (1D) is preferably a resin having only the repeating unit represented by formula (1d). Preferable examples of the resin (1D) include the above-described polyvinylpyrrolidone and the like.

[0064] The weight average molecular weight of the resin (1D) is not particularly limited, but is preferably 10,000 or more and 1,500,000 or less. The lower limit of the weight average molecular weight is more preferably 40,000 or more, still more preferably 50,000 or more, and even more preferably 100,000 or more. Further, the upper limit of the weight average molecular weight is more preferably 1,200,000 or less.

[0065] (Second resin)

[0066] The protective film forming agent according to the present embodiment preferably contains a second resin having an aromatic ring. The second resin may be a resin having an aromatic ring (sometimes referred to as an "aromatic resin"). The aromatic ring may be a monocyclic aromatic ring or a polycyclic aromatic ring. Examples of the aromatic ring having a ring structure include a benzene ring. Examples of the aromatic ring having a polycyclic structure include a naphthalene ring, a biphenyl ring, an anthracene ring, and a phenanthrene ring.

[0067] The second resin is preferably water-soluble. When the second resin is a water-soluble resin, it is more preferably a water-soluble resin having an aromatic ring and a water-soluble group. As used herein, the water-soluble resin includes, as described above, a resin solubilized in water by a hydrolysis reaction or treatment with a base in an aqueous medium. Examples of the water-soluble group include, for example, -SO3 - A + (A + is an alkali metal cation, a proton, or N + R4. R is a hydrogen atom, an alkyl group, or a hydroxyalkyl group.), -COO - A + (A + is an alkali metal cation, a proton, or N + R4. R is a hydrogen atom, an alkyl group, or a hydroxyalkyl group.), a carboxylic anhydride group (-CO-O-CO-), a hydroxyl group, an ether bond (-O-), and the like.

[0068] Note that examples of the alkali metal cation include a sodium cation (Na+ ), potassium cation (K + ), strontium cation (Sr + ), etc. Examples of the above alkyl group include a methyl group, an ethyl group, a propyl group (e.g., n-propyl group, isopropyl group), etc. Examples of the hydroxyalkyl group include a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, etc. Further, the carboxylic anhydride group (-CO-O-CO-) gives -COO - X + by hydrolysis or treatment with a base in water.

[0069] Examples of the second resin include a resin containing a styrene-based unit and a resin containing a phenol-based unit. Examples of the styrene-based unit include a structural unit derived from styrene or a styrene derivative having a substituent at the α-position or on the benzene ring. Examples of the phenol-based unit include a resin containing a phenolic hydroxyl group.

[0070] The resin having a phenolic hydroxyl group may be water-soluble or poorly soluble in water (insoluble in water) depending on its structure. When the resin having a phenolic hydroxyl group is poorly soluble in water, the resin may be treated in a basic aqueous medium to convert the phenolic hydroxyl group into a salt, thereby solubilizing the resin in water.

[0071] The weight average molecular weight of the second resin is not particularly limited, but is usually preferably 100 or more and 300,000 or less. The lower limit of this weight average molecular weight is more preferably 1,000 or more, and even more preferably 10,000 or more. Further, the upper limit of this weight average molecular weight is more preferably 200,000 or less, and even more preferably 150,000 or less.

[0072] A more specific preferred example of the second resin will be described. The second resin preferably contains at least one selected from the group consisting of a resin (2A) containing a repeating unit represented by the following formula (2a-1) and a repeating unit represented by the following formula (2a-2), a resin (2B) containing a repeating unit represented by the following formula (2b-1) and a repeating unit represented by the following formula (2b-2), and a resin (2C) containing a repeating unit represented by the following formula (2c). By using these resins in combination with the above-described metal salt and the first resin, at least the film-forming property and the selectivity can be further improved.

[0073]

Chemical formula

[0074] (In the formula, X + is an alkali metal cation, a proton, or N + R 4 4, and R 4 is a hydrogen atom, an alkyl group, or a hydroxyalkyl group.)

[0075]

Chemical formula

[0076] (In the formula, M 1+ and M 2+ are each independently an alkali metal cation, a proton, or N + R 5 4, and R 5 is a hydrogen atom, an alkyl group, or a hydroxyalkyl group.)

[0077]

Chemical formula

[0078] The resin (2A) may be a resin containing a repeating unit represented by the formula (2a-1) and a repeating unit represented by the formula (2a-2) (see formula (2a)), and may also have other repeating units. From the viewpoints of the film-forming property, selectivity ratio, water washability, precision of the shape of the processing groove, etc. of the protective film, it is preferable that the resin (2A) is a resin having only the repeating unit represented by the formula (2a-1) and the repeating unit represented by the formula (2a-2) (see formula (2a)).

[0079] In formula (2a-2), X + is an alkali metal cation, a proton, or N + R 4 4, and R 4 may be a hydrogen atom, an alkyl group, or a hydroxyalkyl group. Examples of the alkali metal cation include a sodium cation (Na + ), a potassium cation (K + ), a strontium cation (Sr + ), etc. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group (e.g., an n-propyl group, an isopropyl group), etc. Examples of the hydroxyalkyl group include a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, etc.

[0080] Among the above, X + is preferably N + R 4 4, and R 4 is more preferably a hydrogen atom. Specific examples of X + include, for example, X + is preferably NH4 + .

[0081] The water solubility of the resin (2A) can be improved, for example, by increasing the content of the repeating unit represented by the formula (2a-2) having high hydrophilicity.

[0082] The ratio of the repeating unit represented by formula (2a-1) and the repeating unit represented by formula (2a-2) is not particularly limited, but from the above-described viewpoints, the molar ratio of the repeating unit represented by formula (2a-1) to the repeating unit represented by formula (2a-2) (formula (2a-1) / (formula (2a-2))) is preferably 0.1 or more and 9 or less from the viewpoint of ease of imparting water solubility. The lower limit of this molar ratio is more preferably 0.25 or more. Further, the upper limit of this molar ratio is more preferably 7 or less, and even more preferably 4 or less.

[0083] Preferable examples of the resin (2A) include X of formula (2a-2) + is NH4 + The resin can be obtained, for example, by demetallizing (demetalizing) a copolymer containing a dihydroxydiphenylsulfone type repeating unit (see formula (2a-1)) and a phenol type repeating unit of sodium sulfonate (when X of formula (2a-2) + is Na + is as shown in the reference) by hydrochloric acid treatment and then diluting with aqueous ammonia.

[0084] The weight average molecular weight of the resin (2A) is not particularly limited, but is preferably 5000 or more and 300000 or less. The lower limit of the weight average molecular weight is more preferably 10000 or more, even more preferably 15000 or more, and still more preferably 20000 or more. Further, the upper limit of the weight average molecular weight is more preferably 200000 or less, even more preferably 100000 or less, still more preferably 50000 or less, and even more preferably 25000 or less.

[0085] The resin (2B) may be a resin containing a repeating unit represented by formula (2b-1) and a repeating unit represented by formula (2b-2) (see formula (2b)), and may also have other repeating units. From the viewpoints of the film-forming property, selectivity ratio, water washability, precision of the shape of the processing groove, etc. of the protective film, the resin (2B) is preferably a resin having only the repeating unit represented by formula (2b-1) and the repeating unit represented by formula (2b-2) (see formula (2b)).

[0086] In formula (2b-2), M 1+ and M 2+ are, for example, monovalent cations, and each independently is an alkali metal cation, a proton, or N + R 5 4, and R 5 may be a hydrogen atom, an alkyl group, or a hydroxyalkyl group. Examples of the alkali metal cation include a sodium cation (Na + ), a potassium cation (K + ), a strontium cation (Sr + ), etc. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group (e.g., n-propyl group, isopropyl group), etc. Examples of the hydroxyalkyl group include a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, etc.

[0087] Among the above, at least one of M 1+ and M 2+ is preferably N + R 5 4, and R 5 is more preferably a hydrogen atom. Further, it is more preferable that M 1+ and M 2+ are the same. Specific examples of M 1+ and M 2+ are preferably such that at least one is NH4 + , and it is preferable that both M 1+ and M 2+ are NH4 + .

[0088] The water solubility of the resin (2B) can be improved, for example, by increasing the content of the repeating unit represented by the formula (2b-2) having high hydrophilicity.

[0089] The ratio of the repeating unit represented by the formula (2b-1) and the repeating unit represented by the formula (2b-2) is not particularly limited. However, from the above-described viewpoints, the molar ratio of the repeating unit represented by the formula (2b-1) to the repeating unit represented by the formula (2b-2) (formula (2b-1) / (formula (2b-2))) is preferably 1 or more and 8 or less from the viewpoint of ease of imparting water solubility. The lower limit of this molar ratio is more preferably 2 or more. The upper limit of this molar ratio is more preferably 6 or less, still more preferably 5 or less, even more preferably 4 or less.

[0090] As a preferred example of the resin (2B), as described above, M of the formula (2b-2) 1+ and M 2+ both being NH4 + Examples of such a resin include those obtained by diluting a styrene-maleic anhydride copolymer with aqueous ammonia.

[0091] The weight average molecular weight of the resin (2B) is not particularly limited, but is preferably 5,000 or more and 200,000 or less. The lower limit of the weight average molecular weight is more preferably 7,000 or more, still more preferably 8,000 or more. The upper limit of the weight average molecular weight is more preferably 100,000 or less, still more preferably 50,000 or less, even more preferably 40,000 or less, and even more preferably 30,000 or less.

[0092] The resin (2C) may be any resin containing a repeating unit represented by the formula (2c), and may also contain other repeating units. From the viewpoints of the film-forming property of the protective film, the selectivity, the water washability, the precision of the shape of the processing groove, etc., the resin (2C) is preferably a resin having only the repeating unit represented by the formula (2c). Preferable examples of the resin (2C) include polystyrenesulfonic acid.

[0093] The weight average molecular weight of the resin (2C) is not particularly limited, but is preferably 5000 or more and 1200000 or less. The lower limit of the weight average molecular weight is more preferably 10000 or more, still more preferably 15000 or more, and even more preferably 20000 or more. Also, the upper limit of the weight average molecular weight is more preferably 500000 or less, still more preferably 300000 or less, further more preferably 100000 or less, even more preferably 50000 or less, and even further more preferably 30000 or less.

[0094] Note that the protective film-forming agent according to the present embodiment preferably contains only a water-soluble resin as the resin. In that case, the protective film-forming agent according to the present embodiment may further contain other resins other than the above-described first resin and second resin. For example, when the protective film-forming agent according to the present embodiment contains only the first resin as the resin, the first resin is preferably a water-soluble resin. When the protective film-forming agent according to the present embodiment contains only the first resin and the second resin as the resin, the first resin and the second resin are preferably water-soluble resins. When the protective film-forming agent according to the present embodiment contains the first resin, the second resin, and other resins other than the first resin and the second resin as the resin, the first resin, the second resin, and the other resins are all preferably water-soluble resins.

[0095] In the protective film-forming agent according to this embodiment, the content ratios of the first resin and the second resin are not particularly limited. However, the total content of the first resin and the second resin with respect to 100 parts by mass of the solid content in the protective film-forming agent is preferably 99.8 parts by mass or less, and more preferably 99.6 parts by mass or less. Further, the total content of the first resin and the second resin with respect to 100 parts by mass of the solid content in the protective film-forming agent is preferably 80.0 parts by mass or more, and more preferably 90.0 parts by mass or more.

[0096] (Additives, etc.)

[0097] The protective film-forming agent according to this embodiment may contain other additives as necessary. Examples of other additives include light absorbers, basic compounds, dyes, pigments, plasticizers, preservatives, and surfactants.

[0098] (Light absorber)

[0099] As the light absorber, a light absorber generally used in protective film-forming agents can be used. Examples of the light absorber include organic acids having a carboxyl group and / or a sulfo group; sodium salts, potassium salts, ammonium salts, and quaternary ammonium salts of these organic acids; compounds having a hydroxy group, and the like.

[0100] Specific examples of the light absorber include, for example, benzophenone-based compounds, cinnamic acid-based compounds, anthraquinone-based compounds, naphthalene-based compounds, biphenyl-based compounds, water-soluble amines, and the like.

[0101] Specific examples of the benzophenone-based compounds include, for example, benzophenone, 4,4'-dicarboxybenzophenone, benzophenone-4-carboxylic acid, tetrahydroxybenzophenone, 2-(4-diethylamino-2-hydroxybenzoyl)benzoic acid (DHBA), 4,4'-bis(diethylamino)benzophenone, and the like.

[0102] Specific examples of cinnamic acid-based compounds include, for example, cinnamic acid, 4-aminocinnamic acid, 3-aminocinnamic acid, 2-aminocinnamic acid, sinapic acid (3,5-dimethoxy-4-hydroxycinnamic acid), ferulic acid, caffeic acid, and the like. Among these, 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 even more preferred.

[0103] Specific examples of anthraquinone-based compounds include, for example, anthraquinone, 2-carboxyanthraquinone, 2,6-anthraquinonedisulfonic acid, 2,7-anthraquinonedisulfonic acid, and the like.

[0104] Specific examples of naphthalene-based compounds include, for example, naphthalene, 1,2-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and the like.

[0105] Specific examples of biphenyl-based compounds include, for example, biphenyl, biphenyl-4-sulfonic acid, and the like.

[0106] Specific examples of water-soluble amines include, for example, curcumin, and the like.

[0107] Among the above, benzophenone-based compounds, cinnamic acid-based compounds, etc. are preferred, and tetrahydroxybenzophenone, 2-(4-diethylamino-2-hydroxybenzoyl)benzoic acid (DHBA), 4-aminocinnamic acid, etc. are more preferred.

[0108] The content rate of the light absorber in the protective film forming agent according to this embodiment is not particularly limited as long as it does not inhibit the object of this embodiment. However, the content of the light absorber with respect to 100 parts by mass of the solid content in the protective film forming agent is preferably 1 part by mass or more and 10 parts by mass or less. The lower limit of the content of the light absorber with respect to 100 parts by mass of the solid content in the protective film forming agent is more preferably 1.5 parts by mass or more. Further, the upper limit of the content of the light absorber with respect to 100 parts by mass of the solid content in the protective film forming agent is more preferably 7 parts by mass or less, still more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less.

[0109] (Basic compound)

[0110] The protective film forming agent according to this embodiment may contain a basic compound for the purpose of making the solid content more easily soluble. As the basic compound, either an inorganic compound or an organic compound can be used. As the basic compound, an organic compound is preferred.

[0111] Specific examples of the basic compound include, for example, basic inorganic compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, sodium metasilicate, and ammonia; basic organic compounds such as ethylamine, n-propylamine, monoethanolamine (MEA), 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; etc. Among these, monoethanolamine (MEA), ammonia, etc. are more preferred.

[0112] The content rate of the basic compound in the protective film forming agent according to this embodiment is not particularly limited as long as it does not inhibit the object of this embodiment. However, the content of the basic compound with respect to 100 parts by mass of the solid content in the protective film forming agent is preferably 0.1 part by mass or more and 3.0 parts by mass or less. The upper limit of the content of the basic compound with respect to 100 parts by mass of the solid content in the protective film forming agent is more preferably 1.5 parts by mass or less, and still more preferably 1.0 part by mass or less. Also, the lower limit of the content of the basic compound with respect to 100 parts by mass of the solid content in the protective film forming agent is more preferably 0.3 part by mass or more.

[0113] In addition, the molar ratio of the basic compound to the light absorbent (basic compound / light absorbent) is preferably 1 or more, and more preferably 1 or more and 20 or less. The lower limit of the molar ratio of the basic compound to the light absorbent may be 1.5 or more, may be 2 or more, or may be 3 or more. The upper limit of the molar ratio of the basic compound to the light absorbent may be 15 or less, may be 10 or less, or may be 5 or less.

[0114] (Dye)

[0115] As the dye, a water-soluble dye is preferred. Specific examples of water-soluble dyes include, for example, 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), indigoid dyes (indigoid derivatives, thioindigoid 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, azomethine dyes), quinoline dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes, naphthalimide dyes, perinone dyes, and other dyes.

[0116] (Pigment)

[0117] As the pigment, it is preferably a water-soluble pigment. Specific examples of the water-soluble pigment include, for example, 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 Color AM, Food Red No. 1, Food Red No. 4, Food Red No. 101, Food Blue No. 1, Food Blue No. 2, Food Green No. 3, Food Melon Color B, Food Egg Color No. 3 and other food additive pigments. The food additive pigments are suitable from the viewpoint of low environmental impact and the like.

[0118] (Plasticizer)

[0119] By using a plasticizer, the generation of cracks in the protective film can be more effectively suppressed, and the flexibility, elasticity, laser processability, etc. of the protective film can be more effectively improved. Specific examples of the plasticizer include, for example, monosaccharides, disaccharides and the like.

[0120] Specific examples of the monosaccharides include, for example, aldoses (monosaccharides having a formyl group), ketoses (monosaccharides having a carbonyl group), and their derivatives. Examples of the derivatives include aldonic acids (carboxylic acids in which the formyl group at the 1-position of aldoses is converted to a carboxyl group), uronic acids (carboxylic acids in which the hydroxymethyl group at the end of the main chain of monosaccharides is converted to a carboxyl group), aldaric acids (dicarboxylic acids in which both the formyl group at the 1-position of aldoses and the hydroxymethyl group at the end of the main chain are changed to carboxyl groups), and the like.

[0121] Specific examples of the aldoses include, for example, D-glyceraldehyde, D-erythrose, D-threose, D-ribose, D-arabinose, D-xylose, D-lyxose, D-glucose, D-galactose, D-allose, D-altrose, D-mannose, D-gulose, D-idose, D-talose and the like.

[0122] Specific examples of ketoses include, for example, dihydroxyacetone, D-erythrulose, D-xylulose, D-ribulose, D-fructose, D-psicose, D-sorbose, D-tagatose, D-sedoheptulose, and the like.

[0123] Specific examples of derivatives include gluconic acid, glucuronic acid, glucaric acid, inositol, and the like.

[0124] Examples of disaccharides include disaccharides composed of the above monosaccharides described as monosaccharides. Specific examples of disaccharides include, for example, maltose, sucrose, lactose, lactulose, trehalose, cellobiose.

[0125] Among the above, D-ribose, D-xylose, D-glucose, D-galactose, D-fructose, inositol, and maltose are preferred, and D-ribose, D-glucose, D-galactose, D-fructose, inositol, and maltose are more preferred.

[0126] (Preservative)

[0127] From the perspective of further improving the antiseptic effect of the protective film forming agent according to this embodiment and further reducing the treatment load of the waste liquid after semiconductor wafer cleaning, it is preferable to use a preservative. Examples of preservatives include, for example, benzoic acid, butyl paraben, ethyl paraben, methyl paraben, propyl paraben, sodium benzoate, sodium propionate, benzalkonium chloride, benzethonium chloride, benzyl alcohol, cetylpyridinium chloride, chlorobutanol, phenol, phenylethyl alcohol, 2-phenoxyethanol, phenylmercuric nitrate, thimerosal, metacresol, lauryldimethylamine oxide, and the like. These may be used alone or in combination of two or more.

[0128] (Surfactant)

[0129] Surfactants are used, for example, to enhance the defoaming property during the production of the protective film-forming agent, the stability of the protective film-forming agent, the coatability of the protective film-forming agent, and the like. From the viewpoint of defoaming property during the production of the protective film-forming agent, it is preferable to use a surfactant.

[0130] The protective film is formed, for example, by spin-coating a protective film-forming agent. However, unevenness caused by bubbles may occur when forming the protective film. In order to suppress the occurrence of such unevenness, it is preferable to use an antifoaming agent such as a surfactant.

[0131] As the surfactant, a water-soluble surfactant can be preferably used. As the surfactant, any of nonionic surfactants, cationic surfactants, anionic surfactants, and amphoteric surfactants can be used. The surfactant may be silicone-based. A nonionic surfactant is preferable from the viewpoint of detergency.

[0132] (Solvent)

[0133] The protective film-forming agent according to the present embodiment contains a solvent in order to dissolve the above-described solid components. As the solvent, water (for example, pure water, ultrapure water (DIW), ionized water, distilled water, purified water, etc.), an organic solvent, or both can be used. From the viewpoint of less danger of ignition during use and cost, etc., it is preferable that the solvent contains water. Specifically, the solvent is preferably water and an aqueous solution of an organic solvent, and more preferably a combination of water and an organic solvent.

[0134] Specific examples of the organic solvent are not particularly limited, and include methyl alcohol, ethyl alcohol, alkylene glycol, alkylene glycol monoalkyl ether, alkylene glycol monoalkyl ether acetate, and the like.

[0135] 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.

[0136] The organic solvent may be used alone or in combination of two or more.

[0137] The protective film forming agent according to this embodiment may use water and an organic solvent in combination. As the combination of water and the organic solvent, for example, a mixed solvent of water and an alkylene glycol monoalkyl ether is preferable, and a mixed solvent of water and propylene glycol monomethyl ether is more preferable.

[0138] When using a mixed solvent in which water and an organic solvent are used in combination, the content rate of the organic solvent in the mixed solvent (the content rate of the organic solvent with respect to the total of water and the organic solvent; (organic solvent / (water + organic solvent))) is not particularly limited. However, from the viewpoint of flammability, the upper limit of the content rate of the organic solvent in the mixed solvent is preferably less than 50% by mass, more preferably 30% by mass or less, still more preferably 20% by mass or less, and even more preferably 15% by mass or less.

[0139] Also, from the perspective of flammability, it is desirable to reduce the content of the organic solvent in the mixed solvent. However, according to this embodiment, when only a water-soluble resin is used as the resin, the content of the organic solvent can be sufficiently reduced. From such a perspective, as a preferred embodiment achievable by this embodiment, the lower limit of the content of the organic solvent in the mixed solvent can preferably be reduced to 5% by mass or more, more preferably reduced to 3% by mass or more, and still more preferably reduced to 0% by mass or more.

[0140] In this embodiment, when only a water-soluble resin is used as the resin, even if the content of the organic solvent is reduced to the above range, the solid content in the protective film forming agent can be effectively dissolved, which is preferable.

[0141] The solvent is preferably selected so that the protective film forming agent does not have a flash point at 1 atmospheric pressure. Specifically, by adjusting the water content in the protective film forming agent, the flash point of the protective film and the presence or absence of a flash point are adjusted.

[0142] A protective film forming agent without a flash point can ensure a higher level of safety. For example, the protective film forming agent can be placed in a non-explosion-proof environment. Specifically, the handling of the protective film forming agent, such as storage, transportation, and use, can be carried out in a non-explosion-proof environment. For example, not only the introduction of the protective film forming agent into a semiconductor factory but also the formation of the protective film can be carried out in a non-explosion-proof environment. Therefore, a protective film forming agent without a flash point is very advantageous industrially in that an explosion-proof environment such as usually expensive explosion-proof equipment is not required.

[0143] The flash point is obtained by measuring in a tag closed cup at a liquid temperature of 80°C or less and in a Cleveland open cup at a liquid temperature exceeding 80°C under 1 atmospheric pressure. In this specification, even when measured in a Cleveland open cup, if the flash point cannot be measured, it is regarded as having no flash point.

[0144] <Method for manufacturing a protective film, protective film>

[0145] According to this embodiment, a protective film can be obtained by applying the above-mentioned protective film forming agent onto a substrate or the like that is to be protected. Specifically, the method for producing a protective film according to this embodiment preferably includes a step of applying the above-mentioned protective film forming agent onto a substrate to form a protective film. The method of application is not particularly limited, but spin coating, spray coating, die coating, roll coating, flow coating, curtain coating, or the like can be adopted depending on the shape, material, or the like of the object to be protected. Furthermore, after application, post-treatment 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.

[0146] Usually, when a protective film for a semiconductor wafer is produced, spin coating or the like is used. Spin coating includes, for example, (i) a step (discharge step) of coating a protective film forming agent on a coating object (such as a semiconductor wafer) fixed on the stage of a spin coater, (ii) a step (rotation processing step) of removing excess protective film forming agent by centrifugal force by rotating the stage to form a thin film, and (iii) a step (drying step) of removing the work from the spin coater and producing a thin film by natural drying, hot air drying, or the like. Spin coating has the advantages of being able to form a film with little film thickness deviation, and being able to be performed without a vacuum, so that it is excellent in film formation cost and film formation speed, and is therefore suitable as a protective film for semiconductor wafers and also as a protective film for plasma dicing.

[0147] The protective film obtained by this embodiment is a protective film containing a metal salt of tin and a first resin having no aromatic ring. Furthermore, it is preferable that the protective film further contains a second resin having an aromatic ring. The metal salt of tin, the first resin, and the second resin can be those described above. In addition, if necessary, other components may be contained, and as such components, for example, those described above can be used.

[0148] As the salt of the metal salt of tin, as described above, from the viewpoint of film-forming properties and selectivity, it preferably contains at least one selected from the group consisting of sulfates, nitrates, nitrites, and hydrates thereof. Since these salts tend to have high water solubility, the compatibility with other components in the protective film-forming agent becomes even higher, and the film-forming properties and selectivity can be further improved.

[0149] And, in the protective film according to the present embodiment, the content ratio of the metal salt of tin is not particularly limited, but from the viewpoint of having excellent film-forming properties and further increasing the selectivity, it is preferably 500 mass ppb or more. The lower limit of this content ratio is more preferably 600 mass ppb or more, still more preferably 700 mass ppb or more, even more preferably 750 mass ppb or more, and still even more preferably 800 mass ppb or more. The upper limit of this content ratio is more preferably 1000 mass ppb or less, still more preferably 950 mass ppb or less, even more preferably 900 mass ppb or less.

[0150] According to the present embodiment, it is expected to form a protective film excellent in film-forming properties and etching resistance over a wide range of film thicknesses from a thin film thickness to a thick film thickness. As a preferred embodiment, the film thickness of the protective film is preferably 0.1 μm or more and 100 μm or less. The lower limit of the film thickness is more preferably 1 μm or more, still more preferably 3 μm or more. Also, the upper limit of the film thickness is more preferably 50 μm or less, still more preferably 30 μm or less, even more preferably 20 μm or less, and still even more preferably 10 μm or less. In this regard, for example, when forming a protective film by spin coating, for the film thickness within the above range, it is possible to more effectively perform film formation excellent in film-forming properties and selectivity.

[0151] <Method for manufacturing a semiconductor chip>

[0152] By using the protective film forming agent according to this embodiment, a semiconductor wafer can be suitably manufactured by plasma dicing. Typically, the above method for manufacturing a semiconductor chip includes cutting the position of the processing groove (the position corresponding to the street position) in the semiconductor wafer. A preferred example of the method for manufacturing a semiconductor chip according to this embodiment is a method for manufacturing a semiconductor chip by cutting a semiconductor wafer by plasma dicing, (1) A step of applying the above-described protective film forming agent on the semiconductor wafer to form a protective film; (2) A step of irradiating a laser beam at a predetermined position of one or more layers including the protective film on the semiconductor wafer to expose the surface of the semiconductor wafer and form a processing groove having a pattern according to the shape of the semiconductor chip; (3) A step of irradiating the semiconductor wafer on which the processing groove is formed with plasma to cut the position of the processing groove of the semiconductor wafer to obtain a semiconductor chip; The manufacturing method of the semiconductor chip including the above is mentioned.

[0153] Hereinafter, the step of forming the protective film (see step (1)) is also described as the "protective film forming step". The step of forming the processing groove (see step (2)) is also described as the "processing groove forming step". The step of cutting the position of the processing groove in the semiconductor wafer (see step (3)) is also described as the "cutting step".

[0154] (Protective Film Forming Step)

[0155] In the protective film forming step, the above-described protective film forming agent is applied on the semiconductor wafer to form a protective film. The application of the protective film forming agent is preferably performed by spin coating.

[0156] The shape of the processing surface of the semiconductor wafer is not particularly limited as long as the desired processing can be performed on the semiconductor wafer. Typically, the processing surface of the semiconductor wafer has a large number of irregularities. And a recess is formed in a region corresponding to the street. On the processing surface of the semiconductor wafer, a plurality of regions corresponding to semiconductor chips are partitioned by streets.

[0157] Since it is easy to remove the protective film by water washing after processing and to further improve the durability (e.g., selectivity, etc.) of the protective film against plasma irradiation when performing plasma irradiation in the cutting process described later, the film thickness of the protective film is preferably 0.1 μm or more and 100 μm or less. The lower limit of the film thickness is more preferably 1 μm or more, and still more preferably 3 μm or more. Also, the upper limit of the film thickness is more preferably 50 μm or less, still more preferably 30 μm or less, even more preferably 20 μm or less, and even more preferably 10 μm or less.

[0158] Hereinafter, a manufacturing method of semiconductor chips that performs dicing processing using a protective film forming agent on a semiconductor wafer including a plurality of semiconductor chips partitioned by lattice-shaped streets will be described as a preferred embodiment of the manufacturing method of semiconductor chips. Note that the shape and size of the semiconductor chips are not particularly limited and can be appropriately set according to the design of the semiconductor chips.

[0159] In a semiconductor wafer, a laminate in which a functional film for forming an insulating film and a circuit is laminated is provided on the surface of a semiconductor substrate (such as a silicon substrate) such as silicon. A plurality of semiconductor chips such as ICs and LSIs are formed in a matrix in this laminate. Each semiconductor chip is partitioned by streets formed in a lattice shape. And as the insulating film, for example, a low dielectric constant insulator film (Low-k film) made of an inorganic film such as a SiO2 film, or an inorganic film such as SiOF or BSG (SiOB), or an organic film such as a polymer film of a polyimide type or a parylene type can be adopted.

[0160] Then, a protective film forming agent is applied on the surface of the laminate on the semiconductor substrate to form a protective film. In the protective film forming step, for example, a protective film forming agent is applied to the surface of the semiconductor wafer by a spin coater. Note that the application method of the protective film forming agent is not particularly limited as long as a protective film having a desired film thickness can be formed, and various application methods described above can be adopted.

[0161] Subsequently, if necessary, the liquid protective film forming agent that coats the surface is dried. As a result, a protective film is formed on the surface of the semiconductor wafer. As described above, the protective film according to the present embodiment is a protective film in which the generation of cracks is suppressed, having no cracks or few cracks, and having an excellent selectivity ratio. Furthermore, it is possible to form a protective film with suppressed stickiness.

[0162] After the protective film is formed on the surface of the semiconductor wafer in this manner, a protective tape may be attached to the back surface of the semiconductor wafer if necessary.

[0163] (Processing groove formation step)

[0164] In the processing groove formation step, a laser beam is irradiated onto a predetermined position of one or more layers including the protective film on the semiconductor wafer to expose the surface of the semiconductor substrate and form a processing groove having a pattern corresponding to the shape of the semiconductor chip. According to the protective film forming agent and the protective film according to the present embodiment, not only excellent film-forming properties and selectivity ratio are achieved, but also the straightness of the processing groove (the straightness of the side wall of the protective film constituting the processing groove) and the rectangularity of the cross-section of the processing groove (the rectangularity of the cross-section of the protective film constituting the processing groove) are expected to be improved. When the processability is excellent, when cutting by plasma etching, it is possible to accurately cut without deviating from the desired position, so it is also possible to cut with higher positional accuracy.

[0165] Specifically, the laser beam is irradiated onto the surface (street) of the semiconductor wafer through the protective film. From the viewpoint of intensity, an ultraviolet laser having a wavelength of 100 nm or more and 400 nm or less is preferable for the laser. Also, YVO4 lasers, YAG lasers having wavelengths of 266 nm, 355 nm, etc. are preferable.

[0166] The above laser beam irradiation in the processing groove formation step can be performed, for example, under the following processing conditions. Note that the condensing spot diameter can be appropriately selected in consideration of the width of the processing groove. Light source of laser beam: YVO4 laser or YAG laser Wavelength: 355 nm Repetition frequency: 50 kHz or more and 100 kHz or less Output: 0.1 W or more and 4.0 W or less Processing feed rate: 1 mm / second or more and 800 mm / second or less

[0167] By performing the above-described processing groove forming step, in a laminate including a street in a semiconductor wafer, a processing groove is formed along the street. As described above, the protective film according to the present embodiment can suppress the generation of cracks and has excellent durability (for example, selectivity, etc.). Thereby, by irradiating the protective film with laser light, a groove (processing groove) excellent in straightness and cross-sectional rectangularity can be formed in the protective film.

[0168] As described above, when the irradiation of the laser light is performed along a predetermined street, the semiconductor wafer held on the chuck table is indexed and moved by the interval of the streets, and the irradiation of the laser light is performed again.

[0169] In this way, after performing the irradiation of the laser light and the indexing movement for all the streets extending in the predetermined direction, the semiconductor wafer held on the chuck table is rotated by 90 degrees, and along each street extending at right angles to the predetermined direction, the irradiation of the laser light and the indexing movement are performed in the same manner as above. In this way, processing grooves can be formed along all the streets formed in the laminate on the semiconductor wafer.

[0170] (Cutting step)

[0171] In the cutting step, the semiconductor wafer in which the processing grooves are formed is irradiated with plasma to cut the positions of the processing grooves of the semiconductor wafer to obtain semiconductor chips. Specifically, the semiconductor wafer provided with the processing grooves at positions corresponding to the positions of the streets is cut by plasma etching. Since the protective film according to the present embodiment is also suitable as, for example, a protective film for plasma etching, etc., in the manufacturing method of a semiconductor wafer performing a cutting method by plasma etching, its advantages can be exhibited.

[0172] When irradiating with plasma, the plasma is irradiated onto part or all of the surface of the semiconductor wafer having a protective film so that the plasma is exposed on the surface of the processing groove. Hereinafter, an example of a cutting method by plasma irradiation will be described.

[0173] First, irradiate the semiconductor wafer having a protective film and a processing groove with plasma. By doing so, the position of the processing groove in the semiconductor wafer is cut. Specifically, in the semiconductor wafer covered with the protective film, after forming the processing groove as described above, plasma irradiation is performed on the protective film and the surface of the semiconductor substrate exposed from the processing groove. As a result, the semiconductor wafer is cut according to the shape of the semiconductor chip, and the semiconductor wafer is divided into individual semiconductor chips.

[0174] The plasma irradiation conditions are not particularly limited as long as the cutting of the semiconductor wafer at the position of the processing groove can be performed well. The plasma irradiation conditions can be selected according to the material of the semiconductor wafer, the type of plasma, etc., and conditions suitable for plasma etching of the semiconductor substrate can be selected.

[0175] The gas (etching gas) used for plasma generation in plasma irradiation can be appropriately selected according to the material of the semiconductor wafer, etc. For example, SF6 gas or the like can be used. Further, it is preferable to perform the cutting of the semiconductor wafer by adopting the Bosch process and alternately performing sidewall protection by supplying a fluorine-based gas such as C4F6 gas or C4F8 gas and etching of the semiconductor wafer by plasma irradiation. The Bosch process has the advantage that etching with a high aspect ratio is possible, and even when the semiconductor wafer is thick, the cutting of the semiconductor wafer is easy.

[0176] Furthermore, in the Bosch process, since the fluorine-based gas described above is used as an etching gas under vacuum or reduced pressure, fluorine radicals are generated in the system. However, since the protective film according to the present embodiment contains a metal salt of tin, it is possible to effectively suppress the volatilization of fluorine radicals in the system. As a result, there is also an advantage that problems such as unnecessary contamination, etching, or damage of the wafer by the volatilized fluorine radicals can be effectively suppressed.

[0177] And the protective film according to the present embodiment has at least an excellent selectivity ratio. By using such a protective film, it is also expected that a processing groove excellent in straightness and cross-sectional rectangularity can be formed. As a result, it will be possible to accurately cut a desired position by plasma irradiation and obtain a semiconductor chip excellent in straightness.

[0178] In addition, the protective film according to the present embodiment has at least suppression of crack generation and excellent film formability. For this reason, it is possible to sufficiently protect positions other than the cutting position and effectively prevent cutting by plasma irradiation or the like at undesired positions (positions other than the processing groove). And contamination and damage of the semiconductor substrate by a gas such as a fluorine-based gas used in plasma irradiation can also be effectively suppressed.

[0179] Subsequently, the protective film covering the surface of the semiconductor chip is removed. When the protective film contains a water-soluble resin as described above, the protective film can be efficiently washed away with water.

[0180] As described above, an example of a method for manufacturing a semiconductor chip by processing a semiconductor wafer has been described. The method for manufacturing a semiconductor chip according to the present embodiment includes forming a protective film on the surface of the semiconductor wafer and forming a processing groove at a position corresponding to a street on the surface of the semiconductor wafer provided with the protective film, and can be applied to various methods for manufacturing semiconductor chips as long as it is a method of cutting this by plasma irradiation.

[0181] In recent years, in order to increase the number of chips taken out per wafer (number of chips), the width of the streets has been reduced. Furthermore, for small chip devices that are in demand for mobile devices and IoT, further improvement in quality and productivity is desired. In the semiconductor manufacturing process of such devices that require high quality and high productivity, the manufacturing method according to the present embodiment would be particularly suitable as it can solve the above problems of plasma dicing.

Example

[0182] The present invention will be described in more detail with the following examples and comparative examples, but the present invention is not limited to the following examples in any way. Unless otherwise specified below, the quantity is based on mass, and the experiments were conducted under the conditions of 25 °C and atmospheric pressure.

[0183] <Components Used>

[0184] Each component used in this example will be described.

[0185] (1) First water-soluble resin (non-aromatic resin) · Resin (1Aa): Hydroxypropyl cellulose (resin having a repeating unit represented by the following formula (1Aa), weight average molecular weight 25000, manufactured by Nippon Soda Co., Ltd., trade name "HPC-SSL", HPC-SSL)

[0186]

Chemical formula

[0187] (In the formula, R 1 , R 2 , and R 3 are each independently a substituent represented by -H or -CH2CH(OH)CH3, and among all the R 1 , R 2 , and R 3 contained in the resin, at least one is -CH2CH(OH)CH3.)

[0188] · Resin (1Bb): Polyvinyl alcohol (Resin having a repeating unit represented by the following formula (1b-1) and a repeating unit represented by the following formula (1b-2), estimated degree of polymerization 500, manufactured by Kuraray Co., Ltd., trade name "Kuraray Poval PVA-505C", PVA-505C)

Chemical formula

[0189] · Resin (1Cc): Poly-N-vinylacetamide (Resin having a repeating unit represented by the following formula (1c), weight average molecular weight 300,000, manufactured by Resonance Co., Ltd., trade name "PNVA GE191-104", PNVA 104)

[0190]

Chemical formula

[0191] · Resin (1Dd): Polyvinylpyrrolidone (Resin having a repeating unit represented by the following formula (1d), weight average molecular weight 1,200,000, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "Pittcoal K-90", PVP K-90)

[0192]

Chemical formula

[0193] (2) Second water-soluble resin (aromatic resin) · Resin (2Aa): A resin having a repeating unit represented by the following formula (2a-1) and a repeating unit represented by the following formula (2a-2) (see formula (2Aa), weight average molecular weight 22,000) was prepared and used.

[0194]

Chemical formula

[0195] The resin (2Aa) is a resin (2Aaa) as a raw material (refer to the following formula (2Aaa), a resin (2Aaa) having a repeating unit represented by the formula (2aa-1) and a repeating unit represented by the formula (2aa-2) in a molar ratio of 4:1, that is, the molar ratio of the repeating unit represented by the formula (2aa-1) to the repeating unit represented by the formula (2aa-2) (formula (2a-1) / (formula (2a-2)) is 4, weight average molecular weight 22,000, trade name "WSR-SP82" manufactured by Konishi Chemical Industry Co., Ltd.) was obtained by diluting it with an aqueous ammonia solution after hydrochloric acid treatment (WSR-SP82(NH4)).

[0196]

Chemical formula

[0197] · Resin (2Bb): A resin having a repeating unit represented by the formula (2b-1) and a repeating unit represented by the formula (2b-2) (refer to the formula (2Bb), weight average molecular weight 10,000) was prepared and used.

[0198]

Chemical formula

[0199] The resin (2Bb) is a styrene-maleic anhydride copolymer as a raw material (refer to the following formula (2Bbb), a resin (2Bbb) having a repeating unit represented by the formula (2bb-1) and a repeating unit represented by the formula (2bb-2) in a molar ratio of 3:1, that is, the molar ratio of the repeating unit represented by the formula (2bb-1) to the repeating unit represented by the formula (2bb-2) is 3, weight average molecular weight 10,000, trade name "XIRAN 3000P" manufactured by POLYSCOPE) was diluted with an aqueous ammonia solution (ammonia concentration 5% by mass) in a mixed solvent of ultrapure water (DIW) and propylene glycol monomethyl ether (PGME) (mass ratio of DIW / PGME = 85 / 15) so that the resin solid content concentration became 14% by mass, and maleic anhydride was ring-opened to obtain (XIRAN-3000P(NH4)).

[0200]

Chem.

[0201] ·Resin (2 Cc): Polystyrene sulfonic acid (resin having a repeating unit represented by the following formula (2c), weight average molecular weight 22,000, manufactured by Tosoh Finechem Corporation, trade name "PS-1H", PS-1H)

[0202]

Chem.

[0203] Note that both the above-mentioned first water-soluble resin (first resin) and second water-soluble resin (second resin) were those in which 0.5 g or more of the resin dissolved in 100 g of water at 25°C.

[0204] (3) Additive ·Light absorber: 2-(4-diethylamino-2-hydroxybenzoyl) benzoic acid (DHBA) ·Basic compound: Monoethanolamine (MEA)

[0205] <Example 1>

[0206] First, into a mixed solvent of ultrapure water (DIW: De-ionized water) and propylene glycol monomethyl ether (PGME) (mass ratio of DIW / PGME = 85 / 15, content of organic solvent in the mixed solvent is 15% by mass), the components listed in Table 1 were added (100 parts by mass of the first resin (a cellulose derivative obtained by reacting cellulose with propylene oxide, manufactured by Nippon Soda Co., Ltd., trade name "NISSO HPC-SSL"), and tin nitrate was added as a metal salt of tin, and it was diluted to the Sn content and solid content concentration (target solid content concentration, solvent mass ratio = DIW / PGME = 85 / 15) listed in Table 1. Then, it was stirred until the system became a homogeneous system to obtain a protective film forming agent. This protective film forming agent is a protective film forming agent with 100 parts by mass of the first resin (non-aromatic resin) as a solid content, a tin content of 800 mass ppb, and a solid content concentration of 20% by mass).

[0207] Next, using a spin coater, the protective film forming agent was applied to the surface of the silicon substrate, and then left to dry naturally at room temperature for 15 minutes to form a protective film with a film thickness of 5 μm.

[0208] Subsequently, linear plasma irradiation was performed on the surface of the Si substrate on the side of the protective film, and etching for forming a dividing groove was carried out. The plasma irradiation was performed under the following laser irradiation conditions by the Bosch process. ·Bosch process: A sidewall protection step by supplying a fluorine-based gas (C4F8 gas) (a step of plasmaizing the fluorine-based gas and depositing a CF-based protective film on the silicon substrate) and an etching step (removing the film on the bottom surface by the ion assist effect, and reacting Si of the silicon substrate exposed by SF6 plasma irradiation with F atoms generated by plasmaization to remove it as silicon tetrafluoride (SiF4)) were alternately repeated. ·Laser irradiation conditions: Wavelength: 355 nm Frequency: 100 kHz Output: 0.1 W Defocus: -0.1 mm Feed speed: 100 mm / s Pass: 2

[0209] (Measurement of solid content concentration) First, the aluminum case was precisely weighed ( tare weight A (g)). Next, 1 g of the protective film forming agent was precisely weighed and placed in the aluminum case ( measured value: B (g)). This was dried under the conditions of 140 °C for 120 minutes. After drying and cooling to room temperature, it was precisely weighed ( measured value: C (g)). Then, the solid content concentration was calculated based on the following formula. The electronic balance used for precise weighing was capable of weighing up to 0.0001 g units. Solid content concentration (mass %) = (C - A) / (B - A) × 100 A: Tare weight (g) B: Total mass of the sample and the tare weight (g) C: Total mass of the sample and the tare weight after drying (g)

[0210] (Measurement of Sn content) The content ratio of tin in the metal salt in the total amount of the components obtained by removing the solvent from the protective film forming agent ((tin) / (total amount of the components obtained by removing the solvent from the protective film forming agent)) was measured in accordance with the following method. The Sn content in the protective film forming agent was quantified by inductively coupled plasma optical emission spectrometry. The measurement was carried out by the calibration curve method. A calibration curve was created at 4 or more concentration levels, and the measurement was carried out with a correlation coefficient of 0.99 or more for the calibration curve. As the metal reagent used for the calibration curve method, a mixed solvent (metal element concentration 100 mass ppb) of 1 mass part of the multi - element mixed standard solution "XSTC - 622" (metal element concentration 10 mg / L) manufactured by SPEX and 99 mass parts of dimethylacetamide (DMAC) was used.

[0211] (Evaluation of film - forming property (cracks in the protective film)) Under the above conditions, the protective film forming agent was applied onto the silicon substrate by the spin coating method to obtain a protective film with a film thickness of 5 μm. The obtained protective film was dried under reduced pressure up to the measurement environment of SEM (scanning electron microscope) (6.0 Pa). Then, the coated film after drying under reduced pressure was observed with a 10-fold optical microscope, and the film-forming property (the presence or absence of cracks in the protective film) was evaluated based on the following criteria. In the case where cracks occurred (the case of "×"), the measurement of the selection ratio was not performed ( "-" in each table). · "〇": The occurrence of cracks was not confirmed. · "×": The occurrence of cracks was confirmed. For each example, when the surface of the protective film was touched with a finger to confirm the presence or absence of stickiness (tack), it was confirmed that there was no stickiness in any of the examples.

[0212] (Measurement of selection ratio) The selection ratio was determined by calculation based on the following formula. Selection ratio = Film reduction amount of silicon substrate / Film reduction amount of protective film · Film reduction amount of silicon substrate = Film thickness of silicon substrate before irradiation - Film thickness of silicon substrate after irradiation · Film reduction amount of protective film = Film thickness of protective film before irradiation - Film thickness of protective film after irradiation

[0213] <Examples 2 to 8>

[0214] The protective film forming agent was prepared in accordance with Example 1 except that the components of the protective film forming agent were changed to the components described in Table 1. For example, the protective film forming agent of Example 5 is a protective film forming agent with a solid content concentration of 20% by mass, which contains 2.5 parts by mass of 2-(4-diethylamino-2-hydroxybenzoyl)benzoic acid (DHBA) and 0.7 parts by mass of monoethanolamine (MEA) in addition to 96.8 parts by mass of the first resin as the solid content. Also, for the protective film forming agent of Example 5, the molar ratio of MEA / DHBA was 1.1 (=(0.7÷61.08) / (2.5÷246.22).

[0215] <Examples 9 to 14>

[0216] A protective film forming agent was prepared according to Example 1, except that the components of the protective film forming agent were changed to the components described in Table 2. For example, the protective film forming agent of Example 9 contains 90 parts by mass of the first resin (non-aromatic resin) and 10 parts by mass of the second resin (aromatic resin) as solid components, and has a solid content concentration of 18% by mass.

[0217] For Examples 1 to 14, straightness was also evaluated based on the following criteria. As a result, it was confirmed that all the examples were at least "〇" or above ("〇" or "◎"). · "◎": The cross-section of the protective film (side wall of the processing groove) was flat, and a straight groove (trench) without rattling was formed. · "〇": The cross-section of the protective film was relatively flat, and although there was some rattling, a relatively straight groove (trench) was formed. · "△": The cross-section of the protective film was not flat, and a groove (trench) with significant rattling was formed. · "×": Processing failure (the pattern became soft due to the heat of the laser and the shape could not be maintained, and the processing groove could not be formed.)

[0218] <Comparative Examples 1 to 12>

[0219] A protective film forming agent was prepared according to Example 1, except that the components of the protective film forming agent were changed to the components described in Table 3. For example, the protective film forming agent of Comparative Example 1 contains 100 parts by mass of the first resin (non-aromatic resin) as solid components and does not contain a metal salt of tin, and has a solid content concentration of 18% by mass.

[0220] The formulations and evaluation results of Examples 1 to 8 are shown in Table 1, the formulations and evaluation results of Examples 9 to 14 are shown in Table 2, and the formulations and evaluation results of Comparative Examples 1 to 12 are shown in Table 3.

[0221]

Table 1

[0222]

Table 2

[0223]

Table 3

[0224] From the above, it was at least confirmed that according to the protective film forming agent according to this example, a protective film excellent in film forming properties and having a high selectivity can be produced.

Claims

1. A metal salt of tin, a first resin having no aromatic ring, and a solvent are contained in a protective film forming agent.

2. Furthermore, it contains a second resin having an aromatic ring, the protective film forming agent according to Claim 1.

3. In the total amount of the components excluding the solvent from the protective film forming agent, the content ratio of the tin in the metal salt is 500 mass ppm or more, the protective film forming agent according to Claim 1 or 2.

4. The metal salt contains at least one selected from the group consisting of sulfates, nitrates, nitrites, and hydrates thereof, the protective film forming agent according to Claim 1 or 2.

5. The first resin contains at least one selected from the group consisting of cellulose-based resins and vinyl-based resins, the protective film forming agent according to Claim 1 or 2.

6. The first resin is a resin (1A) containing a repeating unit represented by the following formula (1a), a resin (1B) containing a repeating unit represented by the following formula (1b-1) and a repeating unit represented by the following formula (1b-2), a resin (1C) containing a repeating unit represented by the following formula (1c), and a resin (1D) containing a repeating unit represented by the following formula (1d), and contains at least one selected from the group consisting of: the protective film forming agent according to Claim 1 or 2. 【Chemical 1】 (wherein R １ , R ２ , and R ３ are each independently -H, -CH ３ , -CH ２ CH ３ , or -CH ２ CH(OH)CH ３ , and at least one of all R １ , R ２ , and R ３ is a substituent other than -H.) [Chemical Formula 2] 【Chemical 3】 [Chemical Formula 4]

7. The second resin is a resin (2A) containing a repeating unit represented by the following formula (2a-1) and a repeating unit represented by the following formula (2a-2), a resin (2B) containing a repeating unit represented by the following formula (2b-1) and a repeating unit represented by the following formula (2b-2), and a resin (2C) containing a repeating unit represented by the following formula (2c), and contains at least one selected from the group consisting of: the protective film forming agent according to Claim 2. 【Chemical Formula 5】 (wherein X ＋ is an alkali metal cation, a proton, or N ＋ R ４ ４ and R ４ is a hydrogen atom, an alkyl group, or a hydroxyalkyl group.) 【Chemical Formula 6】 (wherein, M １＋ and M ２＋ are each independently an alkali metal cation, a proton, or N ＋ R ５ ４ and R ５ is a hydrogen atom, an alkyl group, or a hydroxyalkyl group.) 【Chemical Formula 7】

8. A metal salt of tin, a first resin having no aromatic ring are contained in a protective film.

9. Furthermore, it contains a second resin having an aromatic ring, the protective film according to Claim 8.

10. The content rate of the tin in the metal salt in the protective film is 500 mass ppm or more, the protective film according to Claim 8 or 9.

11. The film thickness is 0.1 μm or more and 100 μm or less, the protective film according to Claim 8 or 9.

12. A method for manufacturing a protective film, which includes a step of applying the protective film forming agent according to Claim 1 or 2 on a substrate to form a protective film.

13. A method for manufacturing a semiconductor chip for cutting a semiconductor wafer by plasma dicing, ​ Applying the protective film forming agent according to claim 1 or 2 on a semiconductor wafer to form a protective film; Irradiating laser light at a predetermined position of one or more layers including the protective film on the semiconductor wafer to expose the surface of the semiconductor wafer and form processing grooves in a pattern corresponding to the shape of the semiconductor chip; Irradiating plasma onto the semiconductor wafer having the processing grooves formed thereon to cut the positions of the processing grooves of the semiconductor wafer to obtain semiconductor chips; A method for manufacturing semiconductor chips, comprising the above steps.

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