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

Abstract

To provide a protective film formation agent from which a protective film that is excellent in film-formation property when being formed into a protective film and is excellent in plasma etching resistance can be obtained, a method for producing the same, a protective film obtained by the protective film formation agent, and a method for manufacturing a semiconductor chip.SOLUTION: A protective film formation agent contains a first resin having no aromatic ring, a metal salt having a boiling point of 900°C or higher when it is a metal fluoride, and a protective film formation agent containing a solvent.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In the semiconductor device manufacturing process, wafers are formed by laminating insulating films and functional films onto the surface of a semiconductor substrate, such as a silicon substrate, and dividing the resulting laminate into grid-like lines called streets. By cutting the wafer along these streets, multiple semiconductor chips are obtained (chip formation). In other words, each region demarcated by the streets becomes a semiconductor chip such as an IC or LCI.

[0003] Multiple semiconductor chips can be obtained by cutting the wafer along these streets. For example, in optical device wafers, a laminate of gallium nitride-based compound semiconductors is divided into multiple regions by these streets. By cutting along these streets, 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] Such wafer cutting is performed, for example, by plasma dicing. Plasma dicing is a processing technique that cuts wafers into chips by performing dry etching under vacuum or reduced pressure. Plasma dicing uses processes such as the Bosch process, which can cut wafers to a deep depth.

[0005] Patent Document 1 discloses a method for dicing a substrate containing multiple ICs, comprising the steps of: forming a mask on the substrate to cover and protect the ICs, wherein the mask includes a layer of water-soluble material in contact with the upper surface of the ICs; patterning the mask by a laser scribing process to provide a patterned mask with gaps, exposing the substrate regions between the ICs; and plasma etching the substrate through the gaps in the patterned mask to dice the ICs. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Special Publication No. 2014-523112 [Overview of the project] [Problems that the invention aims to solve]

[0007] When cutting wafers using plasma dicing, a protective film is applied to the wafer surface to protect it. The protective film prevents impurities such as cutting debris and other particles generated during dicing from adhering to the wafer surface, but there is still room for improvement in the performance of the protective film.

[0008] Typically, protective films are formed by applying a protective film-forming agent to a wafer and depositing the film. However, if cracks occur in the protective film, impurities such as cutting debris and other particles can adhere to the wafer, contaminating or damaging it. Furthermore, when performing plasma dicing on devices with steps, the protective film thickness may not be sufficient at the top of the steps, resulting in unintended thinning. For these reasons, protective film-forming agents require excellent film-forming properties that can suppress crack formation.

[0009] Furthermore, in plasma dicing, etching gases such as fluorine-based gases are used to etch wafers. During this process, radicals generated from such etching gases (for example, fluorine radicals generated from fluorine-based gases) can unnecessarily etch or damage the wafer. Such unintended etching can lead to increased thinning of the protective film. For this reason, protective film-forming agents require excellent plasma etching resistance.

[0010] This invention has been made in view of the above circumstances, and its main objective is to provide a protective film forming agent that can produce a protective film with excellent film-forming properties and excellent plasma etching resistance, a method for producing the same, a protective film obtained by such a protective film forming agent, and a method for producing a semiconductor chip. [Means for solving the problem]

[0011] As a result of diligent research to achieve the above-mentioned objectives, the present inventors have found that a protective film-forming agent contains a metal salt having a boiling point of 900°C or higher when it is a metal fluoride, a first resin without an aromatic ring, and a solvent, and have completed the present invention.

[0012] In other words, the present invention is as follows. <1> This protective film-forming agent contains a metal salt having a boiling point of 900°C or higher when it is a metal fluoride, a first resin that does not have an aromatic ring, and a solvent. <2> Furthermore, it contains a second resin having an aromatic ring, <1> It is a protective film-forming agent as described above. <3> The content ratio of the metal in the metal salt in the total amount of the components obtained by removing the solvent from the protective film-forming agent is 0.15% by mass or more. <1> or <2> It is a protective film-forming agent as described above. <4> The metal in the metal salt comprises at least one selected from the group consisting 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. <1> ~ <3> It is a protective film-forming agent as described in any of the following. <5> The metal salt comprises at least one selected from the group consisting of sulfates, nitrates, nitrites, and hydrates thereof. <1> ~ <4> It is a protective film-forming agent as described in any of the following. <6> The first resin includes at least one selected from the group consisting of cellulose resins and vinyl resins. <1> ~ <5> It is a protective film-forming agent as described in any of the following. <7> The first resin includes 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). <1> ~ <6> It is a protective film-forming agent as described in any of the following. [ka] (In the formula, R 1 , R 2 , and R 3 Each of these substituents is independently represented as -H, -CH3, -CH2CH3, or -CH2CH(OH)CH3, and all R 1 , R 2 , and R 3 At least one of these substituents is a substituent other than -H. [ka] [ka] [ka] <8> The second resin is at least one selected from the group consisting of a resin (2A) comprising a repeating unit represented by the following formula (2a-1) and a repeating unit represented by the following formula (2a-2), a resin (2B) comprising 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) comprising a repeating unit represented by the following formula (2c). The protective film-forming agent according to any one of <2> to <7>.

Chemical Formula

Chemical Formula

Chemical Formula

[0013] According to the present invention, a protective film forming agent that can produce a protective film with excellent film-forming properties and excellent plasma etching resistance, a method for producing the same, a protective film obtained by such a protective film forming agent, and a method for producing a semiconductor chip can be provided. [Modes for carrying out the invention]

[0014] The following describes in detail embodiments for carrying out the present invention (hereinafter simply referred to as "this embodiment"). This embodiment is illustrative for explaining the present invention and is not intended to limit the present invention to the following content. The present invention can be implemented by modifying it as appropriate within the scope of its gist.

[0015] <Protective film-forming agent>

[0016] The protective film-forming agent according to this embodiment is a protective film-forming agent containing a metal salt having a boiling point of 900°C or higher when it is a metal fluoride, a first resin without an 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 a semiconductor wafer. Through diligent research, the inventors unexpectedly found that by using a resin without an aromatic ring and a metal salt having a boiling point of 900°C or higher when it is a metal fluoride in combination, a protective film with excellent film-forming properties and excellent plasma etching resistance can be obtained.

[0017] (Metal salt, metal)

[0018] The protective film-forming agent according to this embodiment contains a metal salt whose boiling point is 900°C or higher when it is a metal fluoride.

[0019] The type of metal (metal species) in the metal salt is not particularly limited, as long as the metal has a boiling point of 900°C or higher when it is a metal fluoride. From the viewpoint of further improving film-forming properties and plasma etching resistance, it is preferable that the metal in the metal salt contains at least one selected from the group consisting 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.

[0020] Here, as an example, the table below shows the boiling points of fluorides for various metals. Note that "the boiling point of a metallic fluoride is 900°C or higher" means that at least one of the fluorides that the metal can form must have a boiling point of 900°C or higher. For example, in the case of Ag, several fluorides are possible, such as Ag2F, AgF, AgF2, and AgF3, but at least one of them (for example, AgF) must have a boiling point of 900°C or higher.

[0021] [Table 1]

[0022] In the case of a metal fluoride, the content of metals with a boiling point of 900°C or higher is not particularly limited, but from the viewpoint of having excellent film-forming properties while further increasing the selectivity, it is preferable that the metal content ratio of the metal salt to the total amount of components excluding the solvent from the protective film-forming agent ((metal of the metal salt) / (total amount of components excluding the solvent from the protective film-forming agent)) is 0.15% by mass or more. The lower limit of this content ratio is more preferably 1.0% by mass or more, and even more preferably 1.5% by mass or more. The upper limit of this content ratio is preferably 3.5% by mass or less, more preferably 3.0% by mass or less, and even more preferably 2.5% by mass or less.

[0023] The protective film-forming agent according to this embodiment may contain not only metal salts whose boiling point as a metal fluoride is 900°C or higher, but also metal salts whose boiling point as a metal fluoride is less than 900°C. However, from the viewpoint of achieving an even higher level of both film-forming ability and plasma etching resistance, it is preferable that the protective film-forming agent according to this embodiment contains only metal salts whose boiling point as a metal fluoride is 900°C or higher. In other words, it is preferable that the metal in the metal salt contained in the protective film-forming agent is only a metal whose boiling point as a metal fluoride is 900°C or higher.

[0024] Furthermore, from the viewpoint of achieving an even higher level of both film-forming ability and plasma etching resistance, it is preferable that the protective film-forming agent according to this embodiment substantially does not contain metal salts other than 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. Moreover, it is even more preferable that the content of metal salts other than 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 0% by mass. Note that "substantially not contained" in this specification means that the component is not actively added or mixed, and does not exclude the unavoidable presence or mixing.

[0025] Furthermore, the type of metal salt contained in the protective film-forming agent according to this embodiment is not particularly limited. Preferably, the metal salt contains at least one selected from the group consisting of sulfates, nitrates, nitrites, and hydrates thereof. Since these salts tend to be highly water-soluble, their compatibility with other components in the protective film-forming agent is further enhanced, and film-forming properties can be further improved.

[0026] The protective film-forming agent according to this embodiment may contain not only sulfates, nitrates, nitrites, and their hydrates as metal salts, but also other metal salts, or it may not contain metal salts other than sulfates, nitrates, nitrites, and their hydrates as metal salts.

[0027] In the protective film-forming agent according to this embodiment, the content of the metal salt is not particularly limited, but the total content of the metal salt per 100 parts by mass of solids in the protective film-forming agent is preferably 15.0 parts by mass or less, more preferably 9.4 parts by mass or less, even more preferably 9.3 parts by mass or less, and even more preferably 9.0 parts by mass or less. Furthermore, the total content of the metal salt per 100 parts by mass of solids in the protective film-forming agent is preferably 0.15 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.4 parts by mass or more.

[0028] (First resin)

[0029] The first resin is a resin that does not have an aromatic ring (sometimes called a "non-aromatic resin"). Preferably, the first resin is water-soluble (sometimes called 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, and then applying and drying it. Furthermore, the protective film can be easily removed by washing with water after plasma etching. In this specification, "water-soluble" means that 0.5 g or more of the solute (the resin) dissolves in 100 g of water at 25°C.

[0030] In this regard, conventional methods using water-soluble materials to form protective films have the problem of being prone to cracking. Cracks tend to occur especially when the protective film is thick. Furthermore, using water-soluble materials tends to reduce plasma etching resistance. However, according to this embodiment, surprisingly, the combination of the aforementioned metal salt and the first resin can effectively suppress the occurrence of such problems.

[0031] Furthermore, water-soluble resins also include resins that have been made solubilized in water by hydrolysis or treatment with a base in an aqueous medium. For example, a resin that, as a result of such a reaction or treatment, can dissolve 0.5 g or more of solute (the resin) in 100 g of water at 25°C also falls under the definition of "water-soluble resin" as defined herein.

[0032] The first resin preferably contains at least one selected from the group consisting of cellulose resins, vinyl resins, polyalkylene oxides (e.g., 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 cellulose resins and vinyl resins. These are preferably water-soluble.

[0033] The weight-average molecular weight of the first resin is not particularly limited, but is usually preferably between 100 and 300,000. The lower limit of this weight-average molecular weight is more preferably 1,000 or more, and even more preferably 10,000 or more. The upper limit of this weight-average molecular weight is more preferably 200,000 or less, and even more preferably 150,000 or less.

[0034] Unless otherwise specified, the weight-average molecular weights used herein are those obtained by gel permeation chromatography (GPC) analysis, expressed as polystyrene-based weight-average molecular weights (M w ) refers to.

[0035] The cellulosic resin is preferably cellulose or a cellulose derivative, and is water-soluble. Examples of cellulose derivatives include cellulose modified with alkyl groups (methyl groups, ethyl groups, etc.) and cellulose modified with hydroxyalkyl groups (e.g., hydroxymethyl groups, hydroxyethyl groups, hydroxypropyl groups, etc.). Specific examples of cellulose derivatives include at least one selected from the group consisting of methylcellulose, ethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, and hydroxypropylcellulose.

[0036] The weight-average molecular weight of the cellulose resin is not particularly limited, but is preferably between 1,000 and 300,000. The lower limit of this weight-average molecular weight is more preferably 10,000 or more. Furthermore, the upper limit of this weight-average molecular weight is more preferably 200,000 or less, and even more preferably 150,000 or less.

[0037] The vinyl resin is preferably a homopolymer of monomers having vinyl groups, or a copolymer of monomers having vinyl groups, and is water-soluble. Specific examples of vinyl resins include, for example, at least one selected from the group consisting of polyvinyl alcohol resins, poly-N-vinylacetamide, polyvinylpyrrolidone, polyacrylamide, poly(N-alkylacrylamide), polyallylamine, poly(N-alkylallylamine), partially amidated polyallylamine, poly(diallylamine), allylamine-diallylamine copolymer, and polyacrylic acid.

[0038] Specific examples of polyvinyl alcohol-based resins include, for example, polyvinyl alcohol, polyvinyl acetal (including vinyl acetate copolymer), butenediol-vinyl alcohol copolymer, polyvinyl alcohol-polyacrylic acid block copolymer, and polyvinyl alcohol-polyacrylic acid ester block copolymer. Among these, polyvinyl alcohol is preferred.

[0039] The protective film formed on the surface of a semiconductor wafer is usually removed from the surface of the semiconductor wafer or semiconductor chip by washing with water at an appropriate time after the formation of the processing grooves. For this reason, from the viewpoint of the washability of the protective film, it is preferable to use a water-soluble resin with high affinity for water. Among the resins mentioned above, water-soluble resins with high affinity for water are preferred, such as resins having only hydroxyl groups, amide bonds, and / or ether bonds as polar groups, for example, hydroxypropyl cellulose, polyvinyl alcohol, poly-N-vinylacetamide, polyvinylpyrrolidone, polyethylene glycol, etc.

[0040] Furthermore, from the viewpoint of being able to more effectively suppress deterioration of the shape of the processed grooves due to thermal sagging of the protective film, cellulose-based resins and vinyl-based resins are preferred, and hydroxypropyl cellulose, polyvinyl alcohol, poly-N-vinylacetamide, polyvinylpyrrolidone, etc. are more preferred.

[0041] These can be used individually or in combination of two or more.

[0042] A more specific preferred example of the first resin will be described. The first resin preferably includes 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).

[0043] [ka]

[0044] (In the formula, R 1 , R 2 , and R 3 Each of these substituents is independently represented as -H, -CH3, -CH2CH3, or -CH2CH(OH)CH3, and all R 1 , R 2 , and R 3 At least one of these substituents is a substituent other than -H.

[0045] [ka]

[0046] [ka]

[0047] [ka]

[0048] The resin (1A) may be any resin containing repeating units represented by formula (1a), and may also contain other repeating units. From the viewpoint of protective film formation, plasma etching resistance, water washability, and precision of the shape of the processed groove, it is preferable that the resin (1A) is a resin having only the repeating units represented by formula (1a). Specific examples of resin (1A) include cellulose derivatives. Preferred examples of resin (1A) include the methylcellulose, ethylcellulose, and propylenecellulose mentioned above.

[0049] R in equation (1a) 1 , R 2 , and R 3 Each of these substituents can be independently represented as -H, -CH3, -CH2CH3, or -CH2CH(OH)CH3, but R in formula (1a) 1 , R 2 , and R 3 These are substituents that are independently represented as -H or -CH2CH(OH)CH3, and all R 1 , R 2 , and R 3 Of these, at least one is preferably -CH2CH(OH)CH3.

[0050] The weight-average molecular weight of resin (1A) is not particularly limited, but is preferably between 10,000 and 300,000. The lower limit of the weight-average molecular weight is more preferably 15,000 or more, and even more preferably 20,000 or more. The upper limit of the weight-average molecular weight is more preferably 200,000 or less, even more preferably 100,000 or less, and even more preferably 50,000 or less.

[0051] The resin (1B) may be any resin containing repeating units represented by formula (1b-1) and formula (1b-2) (see formula (1b)), and may also contain other repeating units. From the viewpoint of protective film formation, plasma etching resistance, water washability, and precision of the shape of the processed groove, it is preferable that the resin (1B) is a resin having only repeating units represented by formula (1b-1) and formula (1b-2) (see formula (1b)).

[0052] The water solubility of resin (1B) can be improved, for example, by adjusting the content of repeating units represented by formula (1b-1), the content of repeating units represented by formula (1b-2), and the molar ratio of repeating units represented by formula (1b-1) to repeating units represented by formula (1b-2).

[0053] The ratio of repeating units represented by formula (1b-1) and formula (1b-2) is not particularly limited, but from the above viewpoint, the upper limit of the molar ratio of the repeating unit represented by formula (1b-1) in the total of the repeating units represented by formula (1b-1) and formula (1b-2) (formula (1b-1) / (formula (1b-1) + formula (1b-2))) is preferably 0.965 or less, and more 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.

[0054] A preferred example of resin (1B) is the polyvinyl alcohol described above. Polyvinyl alcohol can be obtained, for example, by saponifying polyvinyl acetate, which is obtained by polymerizing vinyl acetate monomer. In that case, a resin having both the repeating unit represented by formula (1b-1) and the repeating unit represented by formula (1b-2) can be obtained, as represented by formula (1b).

[0055] The degree of polymerization of resin (1B) is not particularly limited, but is preferably 300 to 2500. The lower limit of the degree of polymerization is more preferably 500 or higher. The upper limit of the degree of polymerization is more preferably 2000 or lower.

[0056] The resin (1C) may be any resin containing repeating units represented by formula (1c), and may also contain other repeating units. From the viewpoint of protective film formation, plasma etching resistance, water washability, and precision of the shape of the processed groove, it is preferable that the resin (1C) is a resin having only repeating units represented by formula (1c). A suitable example of the resin (1C) is the poly-N-vinylacetamide mentioned above.

[0057] The weight-average molecular weight of resin (1C) is not particularly limited, but is preferably between 200,000 and 1,500,000. The lower limit of the weight-average molecular weight is more preferably 250,000 or more, and even more preferably 500,000 or more. Furthermore, the upper limit of the weight-average molecular weight is more preferably 1,000,000 or less from the viewpoint of film-forming properties, etc.

[0058] The resin (1D) may be any resin containing repeating units represented by formula (1d), and may also contain other repeating units. From the viewpoint of protective film formation, plasma etching resistance, water washability, and precision of the shape of the processed groove, it is preferable that the resin (1D) is a resin having only repeating units represented by formula (1d). A suitable example of the resin (1D) is the polyvinylpyrrolidone mentioned above.

[0059] The weight-average molecular weight of the resin (1D) is not particularly limited, but is preferably between 10,000 and 1,500,000. The lower limit of the weight-average molecular weight is more preferably 40,000 or more, even more preferably 50,000 or more, and even more preferably 100,000 or more. The upper limit of the weight-average molecular weight is more preferably 1,200,000 or less.

[0060] (Second resin)

[0061] The second type of resin is a resin containing aromatic rings (sometimes called an "aromatic resin"). Examples of monocyclic aromatic rings include benzene rings. Examples of polycyclic aromatic rings include naphthalene rings, biphenyl rings, anthracene rings, and phenanthrene rings.

[0062] The second resin is preferably water-soluble. If the second resin is water-soluble, it is more preferably a water-soluble resin having an aromatic ring and a water-soluble group. The water-soluble resin referred to here includes resins that have been made solubilized in water by hydrolysis or treatment with a base in an aqueous medium, as described above. Examples of water-soluble groups include -SO3 - A + (A + These are alkali metal cations, protons, or N + R4. R is a hydrogen atom, an alkyl group, or a hydroxyalkyl group. )-COO - A + (A + These are alkali metal cations, protons, or N + R is R4. R is a hydrogen atom, an alkyl group, or a hydroxyalkyl group. Examples include a carboxylic acid anhydride group (-CO-O-CO-), a hydroxyl group, an ether bond (-O-), etc.

[0063] Examples of the alkyl metal cations mentioned above include sodium cations (Na + ), potassium cation (K + ), strontium cation (Sr + Examples include the above alkyl groups, such as methyl, ethyl, and propyl groups (e.g., n-propyl and isopropyl groups). Examples of hydroxyalkyl groups include hydroxymethyl, hydroxyethyl, and hydroxypropyl groups. In addition, the carboxylic acid anhydride group (-CO-O-CO-) can be converted to -COO by hydrolysis or treatment with a base in water. - X + It is a base that gives [something].

[0064] Examples of the second type of resin include resins containing styrene units and resins containing phenolic units. Examples of styrene units include constituent units derived from styrene or styrene derivatives having substituents on the α-position or benzene ring. Examples of phenolic units include resins containing phenolic hydroxyl groups.

[0065] Resins containing phenolic hydroxyl groups may be water-soluble or sparingly water-soluble (insoluble) depending on their structure. If a resin containing phenolic hydroxyl groups is sparingly water-soluble, it may be made water-soluble by treating it in a basic aqueous medium to convert the phenolic hydroxyl groups into salts.

[0066] The weight-average molecular weight of the second resin is not particularly limited, but is usually preferably between 100 and 300,000. The lower limit of this weight-average molecular weight is more preferably 1,000 or more, and even more preferably 10,000 or more. The upper limit of this weight-average molecular weight is more preferably 200,000 or less, and even more preferably 150,000 or less.

[0067] More specific preferred examples of the second resin will now be described. The second resin preferably includes at least one selected from the group consisting of a resin (2A) containing repeating units represented by the following formula (2a-1) and repeating units represented by the following formula (2a-2), a resin (2B) containing repeating units represented by the following formula (2b-1) and repeating units represented by the following formula (2b-2), and a resin (2C) containing repeating units represented by the following formula (2c). By using these resins in combination with the metal salt and the first resin described above, at least the film-forming properties and plasma etching resistance can be further improved.

[0068] [ka]

[0069] (In the formula, X+ These are alkali metal cations, protons, or N + R 4 4, R 4 (This is a hydrogen atom, an alkyl group, or a hydroxyalkyl group.)

[0070] [ka]

[0071] (In the formula, M 1+ and M 2+ These are, independently, alkali metal cations, protons, or N + R 5 4, R 5 (This is a hydrogen atom, an alkyl group, or a hydroxyalkyl group.)

[0072] [ka]

[0073] The resin (2A) may be any resin containing repeating units represented by formula (2a-1) and formula (2a-2) (see formula (2a)), and may also contain other repeating units. From the viewpoint of protective film formation, plasma etching resistance, water washability, and precision of the shape of the processed groove, it is preferable that the resin (2A) is a resin having only repeating units represented by formula (2a-1) and formula (2a-2) (see formula (2a)).

[0074] In formula (2a-2), X + These are alkali metal cations, protons, or N + R 4 4, R 4 This can be a hydrogen atom, an alkyl group, or a hydroxyalkyl group. Examples of alkyl metal cations include sodium cations (Na + ), potassium cation (K + ), strontium cation (Sr +Examples include ) and others. Examples of alkyl groups include methyl group, ethyl group, propyl group (e.g., n-propyl group, isopropyl group), etc. Examples of hydroxyalkyl groups include hydroxymethyl group, hydroxyethyl group, hydroxypropyl group, etc.

[0075] Among the above, X + is, N + R 4 It is preferable that it be 4, R 4 It is more preferable that it be a hydrogen atom. + For example, X + NH4 + It is preferable that this be the case.

[0076] The water solubility of resin (2A) can be improved, for example, by increasing the content of repeating units represented by formula (2a-2) which have high hydrophilicity.

[0077] The ratio of repeating units represented by formula (2a-1) and formula (2a-2) is not particularly limited, but from the viewpoint described above, the molar ratio of repeating units represented by formula (2a-1) to repeating units 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. The upper limit of this molar ratio is more preferably 7 or less, and even more preferably 4 or less.

[0078] A preferred example of resin (2A) is X of formula (2a-2). + NH4 + Examples of resins include those with a dihydroxydiphenylsulfone type repeating unit (see formula (2a-1)) and a phenol type repeating unit of sodium sulfonate (X of formula (2a-2)). + Na + A copolymer containing (see reference if applicable) can be obtained by demetallizing (demetallizing) it with hydrochloric acid and then diluting it with ammonia water.

[0079] The weight-average molecular weight of resin (2A) is not particularly limited, but is preferably between 5,000 and 300,000. The lower limit of the weight-average molecular weight is more preferably 10,000 or more, even more preferably 15,000 or more, and even more preferably 20,000 or more. The upper limit of the weight-average molecular weight is more preferably 200,000 or less, even more preferably 100,000 or less, even more preferably 50,000 or less, and even more preferably 25,000 or less.

[0080] The resin (2B) may be any resin containing repeating units represented by formula (2b-1) and formula (2b-2) (see formula (2b)), and may also contain other repeating units. From the viewpoint of protective film formation, plasma etching resistance, water washability, and precision of the shape of the processed groove, it is preferable that the resin (2B) is a resin having only repeating units represented by formula (2b-1) and formula (2b-2) (see formula (2b)).

[0081] In formula (2b-2), M 1+ and M 2+ For example, these are monovalent cations, each independently being an alkali metal cation, a proton, or N + R 5 4, R 5 This can be a hydrogen atom, an alkyl group, or a hydroxyalkyl group. Examples of alkyl metal cations include sodium cations (Na + ), potassium cation (K + ), strontium cation (Sr + Examples include ) and others. Examples of alkyl groups include methyl group, ethyl group, propyl group (e.g., n-propyl group, isopropyl group), etc. Examples of hydroxyalkyl groups include hydroxymethyl group, hydroxyethyl group, hydroxypropyl group, etc.

[0082] Among the above, M 1+ and M 2+, at least one of which is N + R 5 (4 is preferable, and R 5 is more preferably a hydrogen atom. Further, M 1+ and M 2+ are further preferably the same. As specific examples of M 1+ and M 2+ , at least one of which is preferably NH4 + , and M 1+ and M 2+ are both preferably NH4 + .

[0083] The water solubility of the resin (2B) can be improved, for example, by increasing the content of the repeating unit represented by formula (2b-2) having high hydrophilicity.

[0084] The ratio of the repeating unit represented by formula (2b-1) to the repeating unit represented by formula (2b-2) is not particularly limited, but from the viewpoint described above, the molar ratio of the repeating unit represented by formula (2b-1) to the repeating unit represented by 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. Further, the upper limit of this molar ratio is more preferably 6 or less, further preferably 5 or less, and even more preferably 4 or less.

[0085] As a preferred example of the resin (2B), as described above, a resin in which both M 1+ and M 2+ in formula (2b-2) are NH4 + may be mentioned. This resin can be obtained, for example, by diluting a styrene-maleic anhydride copolymer with aqueous ammonia.

[0086] The weight-average molecular weight of resin (2B) is not particularly limited, but is preferably between 5,000 and 200,000. The lower limit of the weight-average molecular weight is more preferably 7,000 or more, and even more preferably 8,000 or more. The upper limit of the weight-average molecular weight is more preferably 100,000 or less, even more preferably 50,000 or less, even more preferably 40,000 or less, and even more preferably 30,000 or less.

[0087] The resin (2C) may be any resin containing repeating units represented by formula (2c), and may also contain other repeating units. From the viewpoint of protective film formation, plasma etching resistance, water washability, and precision of the shape of the processed groove, it is preferable that the resin (2C) is a resin having only repeating units represented by formula (2c). A preferred example of resin (2C) is polystyrene sulfonic acid.

[0088] The weight-average molecular weight of the resin (2C) is not particularly limited, but is preferably between 5,000 and 1,200,000. The lower limit of the weight-average molecular weight is more preferably 10,000 or more, even more preferably 15,000 or more, and even more preferably 20,000 or more. The upper limit of the weight-average molecular weight is more preferably 500,000 or less, even more preferably 300,000 or less, even more preferably 100,000 or less, even more preferably 50,000 or less, and even more preferably 30,000 or less.

[0089] In this embodiment, the protective film-forming agent preferably contains only a water-soluble resin. In this case, the protective film-forming agent may further contain other resins other than the first and second resins described above. For example, if the protective film-forming agent according to this embodiment contains only the first resin, it is preferable that the first resin is a water-soluble resin. If the protective film-forming agent according to this embodiment contains only the first and second resins, it is preferable that the first and second resins are water-soluble resins. If the protective film-forming agent according to this embodiment contains the first resin, the second resin, and other resins other than the first and second resins, it is preferable that the first resin, the second resin, and the other resins are all water-soluble resins.

[0090] In the protective film-forming agent according to this embodiment, the content of the first resin and the second resin is not particularly limited, but the total content of the first resin and the second resin per 100 parts by mass of solids 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. Furthermore, the total content of the first resin and the second resin per 100 parts by mass of solids 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.

[0091] (Additives, etc.)

[0092] The protective film-forming agent according to this embodiment may contain other additives as needed. Examples of other additives include light absorbers, basic compounds, dyes, pigments, plasticizers, preservatives, and surfactants.

[0093] (Photo-absorbing agent)

[0094] As the light-absorbing agent, light-absorbing agents commonly used as protective film-forming agents can be used. Examples of light-absorbing agents include organic acids having carboxyl groups and / or sulfo groups; sodium salts, potassium salts, ammonium salts, and quaternary ammonium salts of these organic acids; and compounds having hydroxyl groups.

[0095] Specific examples of light-absorbing agents include, for example, benzophenone compounds, cinnamic acid compounds, anthraquinone compounds, naphthalene compounds, biphenyl compounds, and water-soluble amines.

[0096] Specific examples of benzophenone compounds include, for example, benzophenone, 4,4'-dicarboxybenzophenone, benzophenone-4-carboxylic acid, tetrahydroxybenzophenone, 2-(4-diethylamino-2-hydroxybenzoyl)benzoic acid (DHBA), and EAB-F (4,4'-bis(diethylamino)benzophenone).

[0097] Specific examples of cinnamic acid 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, and caffeic acid. 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.

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

[0099] Specific examples of naphthalene compounds include, for example, naphthalene, 1,2-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid.

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

[0101] Specific examples of water-soluble amines include curcumin, for example.

[0102] Among the above, benzophenone compounds and cinnamic acid compounds are preferred, and tetrahydroxybenzophenone, 2-(4-diethylamino-2-hydroxybenzoyl)benzoic acid (DHBA), and 4-aminocinnamic acid are more preferred.

[0103] The content of the light absorber in the protective film-forming agent according to this embodiment is not particularly limited as long as it does not hinder the purpose of this embodiment, but it is preferable that the content of the light absorber per 100 parts by mass of solids in the protective film-forming agent is 1 part by mass or more and 10 parts by mass or less. It is more preferable that the lower limit of the content of the light absorber per 100 parts by mass of solids in the protective film-forming agent is 1.5 parts by mass or more. Furthermore, it is more preferable that the upper limit of the content of the light absorber per 100 parts by mass of solids in the protective film-forming agent is 7 parts by mass or less, even more preferable that it is 5 parts by mass or less, and even more preferable that it is 3 parts by mass or less.

[0104] (Basic compounds)

[0105] The protective film-forming agent according to this embodiment may contain a basic compound to facilitate the dissolution of solid components. Both inorganic and organic compounds can be used as the basic compound. Organic compounds are preferred as the basic compound.

[0106] Specific examples of basic compounds include basic inorganic compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, sodium metasilicate, and ammonia; and 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. Among these, basic organic compounds are preferred, and monoethanolamine (MEA) and ammonia are more preferred.

[0107] The content of the basic compound in the protective film-forming agent according to this embodiment is not particularly limited as long as it does not hinder the purpose of this embodiment, but it is preferable that the content of the basic compound per 100 parts by mass of solids in the protective film-forming agent is 0.1 parts by mass or more and 3.0 parts by mass or less. The upper limit of the content of the basic compound per 100 parts by mass of solids in the protective film-forming agent is more preferably 1.5 parts by mass or less, and even more preferably 1.0 part by mass or less. Furthermore, the lower limit of the content of the basic compound per 100 parts by mass of solids in the protective film-forming agent is more preferably 0.3 parts by mass or more.

[0108] Furthermore, the molar ratio of the basic compound to the light absorber (basic compound / light absorber) is preferably 1 or more, and more preferably 1 to 20. The lower limit of the molar ratio of the basic compound to the light absorber may be 1.5 or more, 2 or more, or 3 or more. The upper limit of the molar ratio of the basic compound to the light absorber may be 15 or less, 10 or less, or 5 or less.

[0109] (dye)

[0110] As dyes, water-soluble dyes are 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.

[0111] (dye)

[0112] As for the pigment, a water-soluble pigment is preferable. Specific examples of water-soluble pigments include, for example, food additive pigments such as Food Red No. 2, Food Red No. 40, Food Red No. 102, Food Red No. 104, Food Red No. 105, Food Red No. 106, Food Yellow NY, Food Yellow No. 4 Tartrazine, Food Yellow No. 5, Food Yellow No. 5 Sunset Yellow FCF, Food Orange AM, Food Vermilion No. 1, Food Vermilion No. 4, Food Vermilion No. 101, Food Blue No. 1, Food Blue No. 2, Food Green No. 3, Food Melon B, and Food Egg Yellow No. 3. Food additive pigments are preferable from the viewpoint of having a low environmental impact.

[0113] (Plasticizer)

[0114] By using plasticizers, the occurrence of cracks in the protective film can be more effectively suppressed, and the flexibility, elasticity, and laser processability of the protective film can be more effectively improved. Specific examples of plasticizers include monosaccharides and disaccharides.

[0115] Specific examples of monosaccharides include aldoses (monosaccharides containing a formyl group), ketoses (monosaccharides containing a carbonyl group), and their derivatives. Examples of derivatives include aldonic acid (a carboxylic acid in which the formyl group at position 1 of an aldose is converted to a carboxyl group), uronic acid (a carboxylic acid in which the hydroxymethyl group at the end of the main chain of a monosaccharide is converted to a carboxyl group), and aldalic acid (a dicarboxylic acid in which both the formyl group at position 1 of an aldose and the hydroxymethyl group at the end of the main chain are replaced with carboxyl groups).

[0116] Specific examples of aldoses include 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-glucose, D-idosose, and D-talose.

[0117] Specific examples of ketoses include, for instance, dihydroxyacetone, D-erythrolose, D-xylulose, D-ribulose, D-fructose, D-psicose, D-sorbose, D-tagatose, and D-sedoheptulose.

[0118] Specific examples of derivatives include gluconic acid, glucuronic acid, glucaric acid, and inositol.

[0119] Disaccharides include those composed of the monosaccharides described above. Specific examples of disaccharides include maltose, sucrose, lactose, lactulose, trehalose, and cellobiose.

[0120] 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.

[0121] (Preservative)

[0122] From the viewpoint of further improving the preservative effect of the protective film-forming agent according to this embodiment and further reducing the processing load of wastewater after semiconductor wafer cleaning, it is preferable to use a preservative. Examples of preservatives include benzoic acid, butylparaben, ethylparaben, methylparaben, propylparaben, sodium benzoate, sodium propionate, benzalkonium chloride, benzethonium chloride, benzyl alcohol, cetylpyridinium chloride, chlorobutanol, phenol, phenylethyl alcohol, 2-phenoxyethanol, phenylmercury nitrate, thimerosal, metacresol, and lauryldimethylamine oxide. These may be used individually or in combination of two or more.

[0123] (Surfactants)

[0124] Surfactants are used, for example, to improve the defoaming properties, stability, and applicability of protective film-forming agents during their manufacture. From the viewpoint of defoaming properties during the manufacture of protective film-forming agents, the use of surfactants is preferable.

[0125] The protective film is formed, for example, by spin-coating a protective film-forming agent. However, irregularities caused by air bubbles may occur during the formation of the protective film. To suppress the occurrence of such irregularities, it is preferable to use an antifoaming agent such as a surfactant.

[0126] As the surfactant, a water-soluble surfactant is preferably used. Any of the following surfactants can be used: nonionic surfactants, cationic surfactants, anionic surfactants, and amphoteric surfactants. The surfactant may also be silicone-based. Nonionic surfactants are preferred from the viewpoint of cleaning properties.

[0127] (solvent) The protective film-forming agent according to this embodiment contains a solvent to dissolve the solid components described above. The solvent can be water (e.g., pure water, ultrapure water (DIW), ionized water, distilled water, purified water, etc.), an organic solvent, or both. Water is preferred as the solvent due to the reduced risk of ignition during use and cost considerations. Specifically, aqueous solutions of water and organic solvents are preferred, and a combination of water and an organic solvent is more preferred.

[0128] Specific examples of organic solvents, though not particularly limited, include methyl alcohol, ethyl alcohol, alkylene glycol, alkylene glycol monoalkyl ether, and alkylene glycol monoalkyl ether acetate.

[0129] Examples of alkylene glycols include ethylene glycol and propylene glycol. Examples of alkylene glycol monoalkyl ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether. Examples of alkylene glycol monoalkyl ether acetates include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate.

[0130] Organic solvents may be used individually or in combination of two or more types.

[0131] The protective film-forming agent according to this embodiment may be a mixture of water and an organic solvent. As for the combination of water and organic solvent, for example, a mixed solvent of water and alkylene glycol monoalkyl ether is preferred, and a mixed solvent of water and propylene glycol monomethyl ether is more preferred.

[0132] When using a mixed solvent containing both water and an organic solvent, the content of the organic solvent in the mixed solvent (the content of the organic solvent relative 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 of the organic solvent in the mixed solvent is preferably less than 50% by mass, more preferably 30% by mass or less, even more preferably 20% by mass or less, and even more preferably 15% by mass or less.

[0133] Furthermore, from the viewpoint of flammability, it is desirable to reduce the content of organic solvents in the mixed solvent. According to this embodiment, when only water-soluble resins are used as the resin, the content of organic solvents can be sufficiently reduced. From this viewpoint, a preferred embodiment that can be achieved is that the lower limit of the content of organic solvents in the mixed solvent can be reduced to preferably 5% by mass (5% by mass or more), more preferably to 3% by mass (3% by mass or more), and even more preferably to 0% by mass (0% by mass or more).

[0134] In this embodiment, when only a water-soluble resin is used as the resin, it is preferable because the solid content in the protective film-forming agent can be effectively dissolved even when the content of the organic solvent is reduced to the above range.

[0135] The solvent is preferably selected such that the protective film-forming agent does not have a flash point at 1 atmosphere. Specifically, the flash point of the protective film, or whether or not it has a flash point, can be adjusted by adjusting the water content in the protective film-forming agent.

[0136] Protective film-forming agents without a flash point offer even greater safety. For example, they can be stored in non-explosion-proof environments. Specifically, storage, transportation, and use of protective film-forming agents can be carried out in non-explosion-proof environments. For instance, not only can protective film-forming agents be introduced into semiconductor factories, but the formation of protective films can also be carried out in non-explosion-proof environments. Therefore, protective film-forming agents without a flash point offer significant industrial advantages because they eliminate the need for typically expensive explosion-proof equipment and other explosion-proof environments.

[0137] The flash point is obtained by measuring it at 1 atmosphere using a TAG closed-type filter when the liquid temperature is 80°C or below, and by measuring it using a Cleveland open-type filter when the liquid temperature is above 80°C. In this specification, if the flash point cannot be measured even when using a Cleveland open-type filter, it is considered to have no flash point.

[0138] <Method for manufacturing a protective film, protective film>

[0139] According to this embodiment, a protective film can be obtained by applying the above-described protective film-forming agent onto a substrate or the like to be protected. Specifically, the method for manufacturing a protective film according to this embodiment preferably includes a step of applying the above-described protective film-forming agent onto a substrate to form a protective film. The application method is not particularly limited, but depending on the shape and material of the object to be protected, spin coating, spray coating, die coating, roll coating, flow coating, curtain coating, etc. can be used. Furthermore, after application, post-treatment such as drying steps such as natural drying or hot air drying, or light irradiation steps such as ultraviolet irradiation may be performed.

[0140] Typically, when producing protective films for semiconductor wafers, spin coating is employed. Spin coating involves, for example, (i) a process of applying a protective film-forming agent to the object to be coated (such as a semiconductor wafer) fixed on the stage of a spin coater (dispensing process), (ii) a process of removing excess protective film-forming agent by centrifugal force by rotating the stage to form a thin film (rotation process), and (iii) a process of removing the workpiece from the spin coater and forming a thin film by natural drying, hot air drying, etc. (drying process). Spin coating has advantages such as enabling film formation with minimal film thickness deviation and being able to be performed even without a vacuum, resulting in advantages in terms of film formation cost and film formation speed. Therefore, it is suitable as a protective film for semiconductor wafers and even as a protective film for plasma dicing.

[0141] The protective film obtained by this embodiment is a protective film containing a metal salt having a boiling point of 900°C or higher when it is a metal fluoride, and a first resin that does not have an aromatic ring. Furthermore, it is preferable that the protective film further contains a second resin having an aromatic ring. The metal salt (metal salt) having a boiling point of 900°C or higher when it is a metal fluoride, the first resin, and the second resin can be those described above.

[0142] Furthermore, in the protective film according to this embodiment, the content of the metal salt, which has a boiling point of 900°C or higher when it is a metal fluoride, is not particularly limited. However, from the viewpoint of having excellent film-forming properties while further increasing the selectivity, it is preferable that the content ratio of the metal salt in the protective film (metal / protective film) is 0.15% by mass or more. The lower limit of this content ratio is more preferably 1.0% by mass or more, and even more preferably 1.5% by mass or more. The upper limit of this content ratio is preferably 3.5% by mass or less, more preferably 3.0% by mass or less, and even more preferably 2.5% by mass or less.

[0143] In the case of a metal fluoride, the metal having a boiling point of 900°C or higher preferably includes at least one selected from the group consisting 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. For this metal, those having the above-mentioned physical properties and characteristics can be appropriately selected.

[0144] According to this embodiment, it is expected that a protective film with excellent film-forming properties and etching resistance can be formed over a wide range of film thicknesses, from thin to thick. In 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, and even more preferably 3 μm or more. The upper limit of the film thickness is more preferably 50 μm or less, even more preferably 30 μm or less, even more preferably 20 μm or less, and even more preferably 10 μm or less. In this regard, for example, when the protective film is formed by spin coating, it is possible to more effectively form a film with excellent film-forming properties and etching resistance over the above range of film thicknesses.

[0145] <Method of manufacturing semiconductor chips>

[0146] By using the protective film-forming agent according to this embodiment, semiconductor wafers can be suitably manufactured by plasma dicing. Typically, the above semiconductor chip manufacturing method includes cutting the semiconductor wafer at the location of the processing groove (the location corresponding to the street location). A preferred example of the semiconductor chip manufacturing method according to this embodiment is a semiconductor chip manufacturing method in which the semiconductor wafer is cut by plasma dicing. (1) A step of applying the above-mentioned protective film forming agent onto a semiconductor wafer to form a protective film, (2) A step of irradiating laser light onto predetermined locations of one or more layers including a protective film on a semiconductor wafer to expose the surface of the semiconductor wafer and to form processing grooves in a pattern corresponding to the shape of the semiconductor chip, (3) A step of obtaining a semiconductor chip by irradiating a semiconductor wafer on which a processing groove has been formed with plasma to cut the semiconductor wafer at the location of the processing groove, Examples of semiconductor chip manufacturing methods include those mentioned above.

[0147] Hereafter, the process of forming a protective film (see process (1)) will also be referred to as the "protective film formation process." The process of forming a processing groove (see process (2)) will also be referred to as the "processing groove formation process." The process of cutting the semiconductor wafer at the location of the processing groove (see process (3)) will also be referred to as the "cutting process."

[0148] (Protective film formation process)

[0149] In the protective film formation process, the protective film-forming agent described above is applied to the semiconductor wafer to form a protective film. The protective film-forming agent is preferably applied by spin coating.

[0150] The shape of the processed surface of a semiconductor wafer is not particularly limited, as long as it allows for the desired processing of the semiconductor wafer. Typically, the processed surface of a semiconductor wafer has numerous irregularities, with recesses formed in areas corresponding to streets. On the processed surface of a semiconductor wafer, multiple areas corresponding to semiconductor chips are demarcated by streets.

[0151] The thickness of the protective film is preferably 0.1 μm to 100 μm, in order to facilitate the removal of the protective film by washing with water after processing and to further improve the durability of the protective film against plasma irradiation (e.g., plasma etching resistance) when plasma irradiation is performed in the cutting process described later. The lower limit of the film thickness is more preferably 1 μm or more, and even more preferably 3 μm or more. The upper limit of the film thickness is more preferably 50 μm or less, even more preferably 30 μm or less, even more preferably 20 μm or less, and even more preferably 10 μm or less.

[0152] The following describes a preferred embodiment of a semiconductor chip manufacturing method, which involves dicing a semiconductor wafer comprising multiple semiconductor chips partitioned by a grid-like network of streets using a protective film-forming agent. The shape and size of the semiconductor chip are not particularly limited and can be appropriately set according to the semiconductor chip design.

[0153] In semiconductor wafers, a laminate is provided on the surface of a semiconductor substrate (such as a silicon substrate) in which an insulating film and a functional film that forms circuits are stacked. Multiple semiconductor chips such as ICs and LSIs are formed in a matrix on this laminate. Each semiconductor chip is separated by streets formed in a grid pattern. As the insulating film, for example, a low-dielectric constant insulating film (low-k film) can be used, consisting of inorganic films such as SiO2 film, SiOF, BSG (SiOB), or organic films such as polymer films such as polyimide or parylene.

[0154] Then, a protective film-forming agent is applied to the surface of the laminate on the semiconductor substrate to form a protective film. In the protective film formation process, for example, the protective film-forming agent is applied to the surface of the semiconductor wafer by a spin coater. The method of applying the protective film-forming agent is not particularly limited as long as a protective film of the desired thickness can be formed, and various application methods as described above can be used.

[0155] Next, if necessary, the liquid protective film-forming agent covering the surface is dried. This forms a protective film on the surface of the semiconductor wafer. As described above, the protective film according to this embodiment is a protective film that suppresses crack formation, is crack-free or has few cracks, and has excellent plasma etching resistance. Furthermore, it is possible to form a protective film that also suppresses stickiness.

[0156] After a protective film is formed on the surface of the semiconductor wafer in this manner, protective tape may be attached to the back surface of the semiconductor wafer if necessary.

[0157] (Processed groove forming process)

[0158] In the groove formation process, laser light is irradiated onto predetermined locations in one or more layers, including a protective film, on a semiconductor wafer, exposing the surface of the semiconductor substrate and forming grooves in a pattern corresponding to the shape of the semiconductor chip. The protective film forming agent and protective film according to this embodiment are expected to not only have excellent film formation properties and plasma etching resistance, but also to improve the straightness of the grooves (straightness of the side walls of the protective film constituting the grooves) and the rectangularity of the cross-section of the grooves (rectangularity of the cross-section of the protective film constituting the grooves). Excellent processability allows for accurate cutting without deviation from the desired position when cutting by plasma etching, thus enabling cutting with higher positional accuracy.

[0159] Specifically, laser light is irradiated onto the surface (street) of the semiconductor wafer through a protective film. From the viewpoint of intensity, an ultraviolet laser with a wavelength of 100 nm to 400 nm is preferred. In addition, YVO4 lasers and YAG lasers with wavelengths of 266 nm, 355 nm, etc. are preferred.

[0160] The laser beam irradiation in the groove formation process can be performed, for example, under the following processing conditions. The diameter of the focused spot can be appropriately selected considering the width of the groove. Laser light source: YVO4 laser or YAG laser Wavelength: 355nm Repetition frequency: 50kHz to 100kHz Output: 0.1W to 4.0W Machining feed rate: 1 mm / sec to 800 mm / sec

[0161] By performing the groove formation process described above, grooves are formed along the streets in a laminate of semiconductor wafers that have streets. As described above, the protective film according to this embodiment can suppress the occurrence of cracks and has excellent durability (e.g., resistance to plasma etching). As a result, by irradiating the protective film with laser light, grooves (processed grooves) with excellent straightness and rectangular cross-section can be formed in the protective film.

[0162] As described above, once the laser beam is irradiated along the designated street, the semiconductor wafer held on the chuck table is moved by the distance of the street, and the laser beam is irradiated again.

[0163] In this manner, after performing laser irradiation and indexing movement along all streets extending in a predetermined direction, the semiconductor wafer held on the chuck table is rotated 90 degrees, and laser irradiation and indexing movement are performed in the same manner along each street extending perpendicular to the predetermined direction. In this way, processing grooves can be formed along all streets formed in the laminate on the semiconductor wafer.

[0164] (cutting process)

[0165] In the cutting process, a semiconductor wafer with processed grooves is irradiated with plasma to cut the semiconductor wafer at the locations of the processed grooves, thereby obtaining a semiconductor chip. Specifically, a semiconductor wafer having processed grooves at locations corresponding to the street locations is cut by plasma etching. The protective film according to this embodiment is suitable as a protective film for plasma etching, and therefore can demonstrate its advantages in a semiconductor wafer manufacturing method that uses a plasma etching cutting method.

[0166] When irradiating with plasma, the plasma is irradiated to a portion or the entire surface of the semiconductor wafer that has a protective film, so that the plasma is exposed to the surface of the processing groove. An example of a cutting method by plasma irradiation is described below.

[0167] First, a semiconductor wafer equipped with a protective film and processing grooves is irradiated with plasma. This cuts the semiconductor wafer at the location of the processing grooves. Specifically, in a semiconductor wafer covered with a protective film, after forming processing grooves as described above, plasma is irradiated onto the protective film and the surface of the semiconductor substrate exposed from the processing grooves. This cuts the semiconductor wafer according to the shape of the semiconductor chips, dividing the semiconductor wafer into individual semiconductor chips.

[0168] The plasma irradiation conditions are not particularly limited as long as they allow for good cutting of the semiconductor wafer at the location of the processing groove. The plasma irradiation conditions can be selected to be suitable for plasma etching of the semiconductor substrate, taking into account the semiconductor wafer material, plasma type, etc.

[0169] In plasma irradiation, the gas used to generate the plasma (etching gas) can be appropriately selected depending on the material of the semiconductor wafer, but for example, SF6 gas can be used. Furthermore, it is preferable to cut the semiconductor wafer by employing the Bosch process, which alternates between sidewall protection by supplying fluorine-based gases such as C4F6 gas or C4F8 gas and etching the semiconductor wafer by plasma irradiation. The Bosch process has the advantage of enabling etching at high aspect ratios and making it easy to cut semiconductor wafers even when they are thick.

[0170] Furthermore, in the Bosch process, the aforementioned fluorine-based gas is used as an etching gas under vacuum or reduced pressure, which generates fluorine radicals within the system. However, since the protective film according to this embodiment contains a metal whose boiling point in the case of a metallic fluoride is 900°C or higher, the volatilization of fluorine radicals within the system can be effectively suppressed. As a result, there is also the advantage that problems such as unnecessary contamination, etching, or damage to the wafer by volatilized fluorine radicals can be effectively suppressed.

[0171] Furthermore, the protective film according to this embodiment has at least excellent plasma etching resistance. It is also expected that by using such a protective film, it will be possible to create processed grooves with excellent straightness and rectangular cross-section. As a result, it may be possible to obtain semiconductor chips that can be precisely cut at desired locations by plasma irradiation and have excellent straightness.

[0172] Furthermore, the protective film according to this embodiment suppresses crack formation and has excellent film-forming properties. Therefore, it can adequately protect areas other than the cutting position and effectively prevent cutting by plasma irradiation or the like at undesired locations (locations other than the processing groove). In addition, contamination and damage to the semiconductor substrate by gases such as fluorine-based gases used in plasma irradiation can be effectively suppressed.

[0173] Next, the protective film covering the surface of the semiconductor chip is removed. As mentioned above, if the protective film contains a water-soluble resin, the protective film can be efficiently washed away with water.

[0174] The above describes an example of a semiconductor chip manufacturing method by processing a semiconductor wafer. The semiconductor chip manufacturing method according to this embodiment includes forming a protective film on the surface of the semiconductor wafer and forming processing grooves at positions corresponding to streets on the surface of the semiconductor wafer with the protective film, and can be applied to various semiconductor chip manufacturing methods as long as the method involves cutting by plasma irradiation.

[0175] In recent years, there has been a trend towards narrower street sizes to increase the number of chips extracted per wafer. Furthermore, for small chip devices in demand for mobile devices and IoT applications, further improvements in quality and productivity are desired. In semiconductor manufacturing processes for such devices requiring high quality and high productivity, the manufacturing method according to this embodiment is particularly suitable as it can solve the above-mentioned problems associated with plasma dicing. [Examples]

[0176] The present invention will be described in further detail with reference to the following Examples and Comparative Examples, but the present invention is not limited in any way by the following Examples. Note that, unless otherwise specified below, all quantities are based on mass, and all experiments were carried out under conditions of 25°C and atmospheric pressure.

[0177] <Components Used>

[0178] The resins, metal salts, additives and the like used in the present Examples are described below.

[0179] (1) First water-soluble resin (non-aromatic resin) · Resin (1Aa): Hydroxypropyl cellulose (a 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)

[0180] [Chemical Formula]

[0181] (In the formula, in the formula, 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 contained in the resin is -CH2CH(OH)CH3.)

[0182] · Resin (1Bb): Polyvinyl alcohol (a resin having a repeating unit represented by formula (1b-1) below and a repeating unit represented by formula (1b-2), estimated polymerization degree 500, manufactured by Kuraray Co., Ltd., trade name "Kuraray Poval PVA-505C", PVA-505C) [Chemical Formula]

[0183] ·Resin (1Cc): Poly-N-vinylacetamide (a resin having repeating units represented by the following formula (1c), weight-average molecular weight 300,000, manufactured by Showa Denko Corporation, trade name "PNVA GE191-104", PNVA 104)

[0184] [ka]

[0185] • Resin (1Dd): Polyvinylpyrrolidone (a resin having repeating units represented by the following formula (1d), weight-average molecular weight 1,200,000, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "Pitzcol K-90", PVP K-90)

[0186] [ka]

[0187] (2) Second water-soluble resin (aromatic resin) ·Resin (2Aa): A resin having repeating units represented by formula (2a-1) and formula (2a-2) (see formula (2Aa), weight-average molecular weight 22000) was prepared and used.

[0188] [ka]

[0189] The resin (2Aa) was obtained by treating the raw material resin (2Aaa) (see formula (2Aaa) below, a resin (2Aaa) having repeating units represented by formula (2aa-1) and repeating units represented by formula (2aa-2) in a molar ratio of 4:1, i.e., the molar ratio of repeating units represented by formula (2aa-1) to repeating units represented by formula (2aa-2) (formula (2a-1) / (formula (2a-2))) is 4, weight-average molecular weight 22000, product name "WSR-SP82" manufactured by Konishi Chemical Industry Co., Ltd.) with hydrochloric acid and then diluting it with an aqueous ammonia solution (WSR-SP82(NH4)).

[0190] [ka]

[0191] ·Resin (2Bb): A resin having repeating units represented by formula (2b-1) and formula (2b-2) (see formula (2Bb), weight-average molecular weight 10,000) was prepared and used.

[0192] [ka]

[0193] The resin (2Bb) was obtained by diluting the raw material, a styrene-maleic anhydride copolymer (see formula (2Bbb) below, a resin (2Bbb) having repeating units represented by formula (2bb-1) and repeating units represented by formula (2bb-2) in a molar ratio of 3:1, i.e., the molar ratio of repeating units represented by formula (2bb-1) to repeating units represented by formula (2bb-2) is 3, weight-average molecular weight 10000, trade name "XIRAN 3000P" manufactured by POLYSCOPE), with an aqueous ammonia solution (ammonia concentration 5% by mass) to open the ring of maleic anhydride, resulting in a resin solids content concentration of 14% by mass.

[0194] [ka]

[0195] ·Resin (2Cc): Polystyrene sulfonic acid (a resin having repeating units represented by the following formula (2c), weight-average molecular weight 22,000, manufactured by Tosoh Finechem Co., Ltd., trade name "PS-1H", PS-1H)

[0196] [ka]

[0197] Furthermore, both the first and second water-soluble resins described above were such that 0.5 g or more of the resin could be dissolved in 100 g of water at 25°C.

[0198] (3) Metal salts Sodium sulfate Sodium nitrate Calcium nitrate tetrahydrate Zirconium nitrate dihydrate Aluminum nitrate nonahydrate Note that the mass parts of the metal salt hydrates listed in each table represent the mass parts of the metal salt only, excluding the water in the hydrate.

[0199] (4) Additives • Light-absorbing agent: 2-(4-diethylamino-2-hydroxybenzoyl)benzoic acid (DHBA) • Basic compound: Monoethanolamine (MEA)

[0200] <Example 1>

[0201] First, to a mixed solvent of ultrapure water (DIW: De-ionized water) and propylene glycol monomethyl ether (PGME) (mass ratio DIW / PGME = 85 / 15, organic solvent content in the mixed solvent is 15 mass%), the components described in Table 2 (99.54 parts by mass of the first resin (a cellulose derivative obtained by reacting propylene oxide with cellulose, manufactured by Nippon Soda Co., Ltd., trade name "NISSO HPC-SSL") and 0.46 parts by mass of sodium sulfate) were added, and the mixture was diluted to the solid content concentration (target solid content concentration, solvent mass ratio = DIW / PGME = 85 / 15) described in Table 2. Then, the system was stirred until it became a homogeneous system to obtain a protective film-forming agent. This protective film-forming agent is a protective film-forming agent with a solid content concentration of 20 mass%, containing 99.54 parts by mass of the first resin (non-aromatic resin) and 0.46 parts by mass of a metal salt as the solid content.

[0202] Next, using a spin coater, the protective film-forming agent was applied to the surface of a silicon substrate, followed by natural drying at room temperature for 15 minutes to form a protective film with a thickness of 5 μm.

[0203] Subsequently, the surface of the Si substrate on the protective film side was linearly irradiated with plasma to perform etching for forming dividing grooves. The plasma irradiation was performed by the Bosch process under the following laser irradiation conditions. ·Bosch process: The side wall protection step by supplying fluorine gas (C4F8 gas) (a step of converting the fluorine gas into plasma to deposit a CF-based protective film on the silicon substrate) and the etching step (an etching step of 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 plasma conversion to remove them 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 rate: 100 mm / s Pass:2

[0204] (Measurement of solid content concentration) First, an aluminum case was precisely weighed (tare A (g)). Next, 1 g of the protective film forming agent was precisely weighed and placed in the aluminum case (weighed value: B (g)). This was dried under the conditions of 140°C for 120 minutes. After drying, it was cooled to room temperature and then precisely weighed (weighed 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 down to the 0.0001 g unit. Solid content concentration (mass%) = (C-A) / (B-A) × 100 A: Mass of the tare (g) B: Total mass of the sample and the tare (g) C: Total mass of the sample after drying and the tare (g)

[0205] (Measurement of metal content) The metal content in the protective film forming agent was quantified by inductively coupled plasma optical emission spectrometry. The measurement was performed by the calibration curve method, a calibration curve was prepared at 4 or more concentration levels, and the measurement was carried out at a correlation coefficient of 0.99 or higher for the calibration curve. As the metal reagent used for the calibration curve method, a mixed solution (metal element concentration 100 mass ppb) of 1 part by mass of the multi-element mixed standard solution "XSTC-622" (metal element concentration 10 mg / L) manufactured by SPEX and 99 parts by mass of dimethylacetamide (DMAC) was used.

[0206] (Evaluation of film formability (cracks in protective film)) Under the conditions described above, the protective film forming agent was applied onto a silicon substrate by spin coating to obtain a protective film having a film thickness of 5 μm. The obtained protective film was dried under reduced pressure up to the measurement environment (6.0 Pa) of a SEM (scanning electron microscope). Then, the coated film after drying under reduced pressure was observed with a 10× optical microscope, and the film formability (presence or absence of cracks in the protective film) was evaluated based on the following criteria. When cracks occurred (in the case of "×"), the measurement of the selection ratio was not performed ("-" in each table). • "〇": No cracks were detected. • "×": Cracks have been detected. Furthermore, in Examples 1 to 17, when the surface of the protective film was touched with a finger to check for stickiness (tackiness), it was confirmed that there was no stickiness in any of the examples.

[0207] (Measurement of selectivity ratio) The selection ratio was calculated based on the following formula. Selectivity ratio = Amount of film loss on the silicon substrate / Amount of film loss on the protective film • Amount of film loss on the silicon substrate = Film thickness of the silicon substrate before irradiation - Film thickness of the silicon substrate after irradiation • Amount of protective film loss = Protective film thickness before irradiation - Protective film thickness after irradiation

[0208] <Examples 2-11>

[0209] 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 those listed in Table 2. The protective film-forming agent of Example 7 contains 91.26 parts by mass of the first resin and 5.54 parts by mass of the metal salt, in addition to 2.5 parts by mass of 2-(4-diethylamino-2-hydroxybenzoyl)benzoic acid (DHBA) and 0.7 parts by mass of monoethanolamine (MEA), with a solid content concentration of 20% by mass. Furthermore, the molar ratio of MEA / DHBA in the protective film-forming agent of Example 7 was 1.1 (= (0.7 ÷ 61.08) / (2.5 ÷ 246.22)).

[0210] <Examples 12-17>

[0211] A protective film-forming agent was prepared in accordance with Example 1, except that the components of the protective film-forming agent were changed to those described in Table 3. For example, the protective film-forming agent of Example 12 is a protective film-forming agent with a solid content concentration of 18 mass%, which contains, as solid contents, 85.01 parts by mass of the first resin (non-aromatic resin), 9.45 parts by mass of the second resin (aromatic resin), and 5.54 parts by mass of a metal salt.

[0212] In addition, for Examples 1 to 17, straightness was also evaluated based on the following criteria. As a result, it was confirmed that all Examples were at least "○" or higher ("○" or "◎"). ·"◎": The cross section of the protective film (the side wall of the processed groove) was flat, and a straight trench with no backlash was formed. ·"○": The cross section of the protective film was relatively flat, and a relatively straight trench with slight backlash was formed. ·"△": The cross section of the protective film was not flat, and a trench with large backlash was formed. ·"×": Processing failure (the pattern became softer due to the heat of the laser and could not maintain its shape, so the processed groove could not be formed.)

[0213] <Comparative Examples 1 to 12>

[0214] A protective film-forming agent was prepared in accordance with Example 1, except that the components of the protective film-forming agent were changed to those described in Table 4. For example, the protective film-forming agent of Comparative Example 1 is a protective film-forming agent with a solid content concentration of 18 mass%, which contains only 100 parts by mass of the first resin (non-aromatic resin) as the solid content.

[0215] The formulations and evaluation results of Examples 1 to 11 are shown in Table 2, the formulations and evaluation results of Examples 12 to 17 are shown in Table 3, and the formulations and evaluation results of Comparative Examples 1 to 12 are shown in Table 4.

[0216]

Table 2

[0217] [Table 3]

[0218] [Table 4]

[0219] Based on the above, it has been confirmed that the protective film-forming agent according to this embodiment can produce a protective film with excellent film-forming properties and a high selectivity ratio.

Claims

1. Metal salts whose boiling point is 900°C or higher when they are metal fluorides, A first resin that does not have an aromatic ring, A second resin having an aromatic ring, Solvent and It contains, A protective film-forming agent wherein the second resin comprises at least one selected from the group consisting of a resin (2A) containing repeating units represented by the following formula (2a-1) and repeating units represented by the following formula (2a-2), a resin (2B) containing repeating units represented by the following formula (2b-1) and repeating units represented by the following formula (2b-2), and a resin (2C) containing repeating units represented by the following formula (2c). 【Chemistry 1】 (In the formula, X+ is an alkali metal cation, a proton, or N+R44, where R4 is a hydrogen atom, an alkyl group, or a hydroxyalkyl group.) 【Chemistry 2】 (In the formula, M1+ and M2+ are each independently an alkali metal cation, a proton, or N+R54, and R5 is a hydrogen atom, an alkyl group, or a hydroxyalkyl group.) 【Transformation 3】

2. The content ratio of the metal in the metal salt in the total amount of the components obtained by removing the solvent from the protective film-forming agent is 0.15% by mass or more. The protective film-forming agent according to claim 1.

3. The metal in the metal salt includes at least one selected from the group consisting 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. The protective film-forming agent according to claim 1.

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

5. The first resin includes at least one selected from the group consisting of cellulose resins and vinyl resins. The protective film-forming agent according to claim 1.

6. The first resin includes 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). The protective film-forming agent according to claim 1. 【Chemistry 4】 (In the formula, 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.) 【Transformation 5】 【Transformation 6】 【Transformation 7】

7. Metal salts whose boiling point is 900°C or higher when they are metal fluorides, A first resin that does not have an aromatic ring, A second resin having an aromatic ring and It contains, A protective film wherein the second resin comprises at least one selected from the group consisting of a resin (2A) containing repeating units represented by the following formula (2a-1) and repeating units represented by the following formula (2a-2), a resin (2B) containing repeating units represented by the following formula (2b-1) and repeating units represented by the following formula (2b-2), and a resin (2C) containing repeating units represented by the following formula (2c). 【Transformation 8】 (In the formula, X+ is an alkali metal cation, a proton, or N+R44, where R4 is a hydrogen atom, an alkyl group, or a hydroxyalkyl group.) 【Chemistry 9】 (In the formula, M1+ and M2+ are each independently an alkali metal cation, a proton, or N+R54, and R5 is a hydrogen atom, an alkyl group, or a hydroxyalkyl group.) 【Chemistry 10】

8. The metal content of the metal salt in the protective film is 0.15% by mass or more. The protective film according to claim 7.

9. The metal in the aforementioned metal salt includes at least one selected from the group consisting 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. The protective film according to claim 7.

10. The film thickness is 0.1 μm or more and 100 μm or less. The protective film according to claim 7.

11. The process includes applying the protective film-forming agent described in claim 1 onto a substrate to form a protective film, A method for manufacturing a protective film.

12. A method for manufacturing semiconductor chips by cutting semiconductor wafers using plasma dicing. A step of forming a protective film by applying the protective film forming agent described in claim 1 onto a semiconductor wafer, A step of irradiating laser light onto predetermined positions of one or more layers including the protective film on the semiconductor wafer, exposing the surface of the semiconductor wafer and forming processing grooves in a pattern corresponding to the shape of the semiconductor chip, A step of obtaining a semiconductor chip by irradiating the semiconductor wafer in which the processing grooves are formed with plasma to cut the semiconductor wafer at the location of the processing grooves, A method for manufacturing semiconductor chips, including

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