Photosensitive element, method for forming resist pattern, and method for manufacturing wiring board

Abstract

To provide a photosensitive element capable of forming a resist pattern excellent in adhesion of the resist pattern to a substrate and plated copper wiring formability.SOLUTION: The photosensitive element includes a support film and a photosensitive resin layer containing a photosensitive resin composition. The photosensitive resin composition contains, based on the total solid mass in the photosensitive resin composition, the following components: (A) 30-70 mass% of an alkali-soluble polymer; (B) 20-60 mass% of compounds having ethylenically unsaturated bonds; and (C) 4.0-10.0 mass% of a biimidazole photopolymerization initiator. The content of a constituent unit derived from benzyl (meth)acrylate in the component (A) is 40 mass% or more based on the whole component (A). The content of a compound having two ethylenically unsaturated bonds in one molecule in the component (B) is 80 mass% or more based on the whole component (B).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a photosensitive element and a method for forming a resist pattern. [Background technology]

[0002] Printed wiring boards are generally manufactured using a photolithography process. In photolithography, a coating containing a photosensitive resin composition is first formed on a substrate, and the coating is then subjected to pattern exposure and development to form a resist pattern. A conductor pattern is then formed by etching or plating. The resist pattern on the substrate is then removed to form a predetermined wiring pattern on the substrate.

[0003] In recent years, with the miniaturization and high density of electronic devices, finer wiring patterns than before are required. In relation to such demands, MSAP (Modified Semi Additive Process) and SAP (Semi Additive Process) have been attracting attention. In these methods, in order to form fine wiring, for example, it is desired to form a resist pattern having adhesion and resolution of 7 μm or less. In relation to the viewpoint of forming such a resist pattern, Patent Document 1 discloses a photosensitive resin composition containing a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and an anthracene-based sensitizer, the binder polymer having a hydroxyalkyl (meth)acrylate unit and a styrene or styrene derivative unit, and including a polymer (a) having a content of the styrene or styrene derivative unit of 40 mass% or more. Patent Document 1 also discloses a photosensitive element having a photosensitive resin layer formed using such a photosensitive resin composition on a support. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 193232 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the photosensitive element of Patent Document 1, it was difficult to form a resist pattern that achieved both good adhesion of the resist pattern to the substrate and the ability to form plated copper wiring.

[0006] Therefore, an object of the present invention is to provide a photosensitive element capable of forming a resist pattern excellent in adhesion of the resist pattern to a substrate and in formability of plated copper wiring, and also to provide a method of forming a resist pattern using such a photosensitive element. [Means for solving the problem]

[0007] [1] A photosensitive element comprising a support film and a photosensitive resin layer containing a photosensitive resin composition, The photosensitive resin composition contains the following components based on the total solid content by mass in the photosensitive resin composition: (A) alkali-soluble polymer: 30 to 70 mass %; (B) a compound having an ethylenically unsaturated bond: 20 to 60% by mass; and (C) biimidazole photopolymerization initiator: 4.0 to 10.0 mass%; Including, The content of the structural unit derived from benzyl (meth)acrylate in the component (A) is 40 mass% or more based on the entire component (A), The content of the compound having two ethylenically unsaturated bonds in one molecule in the component (B) is 80 mass% or more based on the entire component (B). Photosensitive element. [2] 2. The photosensitive element according to item 1, wherein the content of the component (C) is 4.50% by mass or more based on the total solid content mass of the photosensitive resin composition. [3] 3. The photosensitive element according to item 1 or 2, wherein the content of the component (C) is 4.75% by mass or more based on the total solid content by mass of the photosensitive resin composition. [4] 4. The photosensitive element according to any one of items 1 to 3, wherein the content of the component (C) is 5.25% by mass or more based on the total solid content by mass of the photosensitive resin composition. [5] 5. The photosensitive element according to any one of items 1 to 4, wherein the content of the component (C) is 6.00% by mass or more based on the total solid content by mass of the photosensitive resin composition. [6] 6. The photosensitive element according to any one of items 1 to 5, wherein the content of the structural unit derived from benzyl (meth)acrylate in the component (A) is 50% by weight or more based on the entire component (A). [7] 7. The photosensitive element according to any one of items 1 to 6, wherein the content of the structural unit derived from benzyl (meth)acrylate in the component (A) is 60% by weight or more based on the entire component (A). [8] 8. The photosensitive element according to any one of items 1 to 7, wherein the content of the compound having two ethylenically unsaturated bonds in one molecule is 90% by mass or more based on the entirety of component (B). [9] The compound having two ethylenically unsaturated bonds in one molecule is represented by the following general formula (II): [ka] (In the formula, R2 is each independently a hydrogen atom or a methyl group, X2O and Y2O are each independently an oxyethylene group or an oxypropylene group, m3, m4, n2, and n3 are each independently an integer of 0 to 40, m3+m4 is 1 to 40, and n2+n3 is 0 to 20.) 9. The photosensitive element according to any one of items 1 to 8, comprising a compound represented by the formula:

[10] 10. The photosensitive element according to item 9, wherein the content of the compound represented by the general formula (II) is 90% by mass or more based on the entirety of the component (B).

[11] The compound having two ethylenically unsaturated bonds in one molecule is A compound in which the average value of n2+n3+m3+m4 in the general formula (II) is 10 or less; and a compound in which, in general formula (II), the average value of n2+n3+m3+m4 is 15 or more.

[12] The photosensitive resin composition contains the component (C) in an amount of 5.0% by mass or more based on the total solid content by mass, The photosensitive resin layer has an absorbance (Y) of 0.35 or less at a wavelength of 365 nm when the layer has a thickness of 25 μm; the contribution (X) of the absorbance of the (C) component to the absorbance (Y) is 40% or more; The contribution (X) is expressed by the following formula (1): X(%)= 100×εc / absorbance of photosensitive resin layer (Y) (1) ε: Change in absorbance per 1 mass% of component (C) c: Content (mass%) of component (C) relative to the total solid component mass of the photosensitive resin composition 12. The photosensitive element according to any one of items 1 to 11, wherein the photosensitive element has a refractive index calculated by the following formula:

[13] 13. The photosensitive element of item 12, wherein the contribution (X) is 55% or greater.

[14] 14. The photosensitive element of item 12 or 13, wherein the contribution (X) is 65% or greater.

[15] 15. The photosensitive element of any one of items 12 to 14, wherein the contribution (X) is 85% or greater.

[16] 16. The photosensitive element according to any one of items 12 to 15, wherein the absorbance (Y) is 0.30 or less.

[17] 17. The photosensitive element according to any one of items 12 to 16, wherein the absorbance (Y) is 0.25 or less.

[18] The photosensitive resin composition comprises (D) Other photopolymerization initiators Further comprising: 18. The photosensitive element according to any one of items 1 to 17, wherein the component (D) includes at least one selected from the group consisting of a benzophenone compound, a pyrazoline compound, an anthracene compound, and a coumarin compound.

[19] The photosensitive resin composition further contains (D) another photopolymerization initiator, 19. The photosensitive element of item 18, wherein the component (D) includes at least one selected from the group consisting of a benzophenone compound and a pyrazoline compound.

[20] The photosensitive resin composition comprises (E) Polymerization inhibitor 20. The photosensitive element of any one of the preceding items, further comprising: [twenty one] 21. The photosensitive element according to item 20, further comprising phenothiazine and / or tert-butylcatechol as the (E) polymerization inhibitor. [twenty two] 22. The photosensitive element according to item 20 or 21, wherein the content of the polymerization inhibitor (E) is 50 to 500 ppm based on the total solid content by mass of the photosensitive resin composition. [twenty three] 23. The photosensitive element according to any one of items 1 to 22, wherein the support film has an absorbance at 365 nm of 0.1 or less. [twenty four] 24. The photosensitive element of any one of items 1 to 23, further comprising a protective film. [twenty five] A method for forming a resist pattern using the photosensitive element according to any one of items 1 to 24, The process is as follows: laminating the photosensitive element to a substrate; exposing the photosensitive resin layer of the laminated photosensitive element to light; and a step of developing the photosensitive resin layer after exposure; A method for forming a resist pattern comprising the steps of:

[26] 25. A photosensitive element roll formed by winding the photosensitive element according to any one of items 1 to 24.

[27] forming a resist pattern on a substrate using the photosensitive element according to any one of items 1 to 24; forming a conductor pattern by etching or plating the substrate on which the resist pattern has been formed; peeling the resist pattern from the substrate; A method for manufacturing a wiring board comprising:

[28] A step of forming a resist pattern on a substrate made of a metal-coated insulating plate using the photosensitive element according to any one of items 1 to 24; forming a conductor pattern by plating the substrate on which the resist pattern is formed; peeling the resist pattern from the substrate; removing the conductor layer other than the conductor pattern; A method for manufacturing a wiring board comprising the steps of:

[29] Item 29. The method for producing a wiring board according to item 28, which forms a wiring board having a conductor pattern with a width of 10 μm or less. Effect of the Invention

[0008] The present invention can provide a photosensitive element capable of forming a resist pattern excellent in adhesion of the resist pattern and in formability of plated copper wiring. The present invention can also provide a method for forming a resist pattern using such a photosensitive element. [Brief description of the drawings]

[0009] [Figure 1] FIG. 4 is a plan view for explaining an example of a “foreign object” assumed in the present embodiment. [Diagram 2]FIG. 2 is a plan view showing a configuration of a mask pattern related to the present embodiment. [Diagram 3] FIG. 2 is a plan view showing a configuration of a mask pattern related to the present embodiment. [Figure 4] FIG. 2 is a plan view showing a configuration of a mask pattern related to the present embodiment. [Diagram 5] FIG. 11 is a diagram showing an example of an observation image related to the present embodiment. [Figure 6] FIG. 11 is a diagram showing an example of an observation image related to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The present invention is not limited to the present embodiment, and various modifications can be made within the scope of the present invention.

[0011] In the present specification, when a plurality of structures represented by the same symbol exist in the same formula, the structures may be independently selected and may be the same or different from each other, unless otherwise specified. When a plurality of structures represented by the same symbol exist in different formulas, the structures may be independently selected and may be the same or different from each other, unless otherwise specified. In the present specification, various measurements are performed based on the methods described in the Examples, unless otherwise specified.

[0012] In this specification, the upper or lower limit value of a numerical range described stepwise may be replaced by the upper or lower limit value of a corresponding numerical range described stepwise in another stepwise manner, and may further be replaced by a corresponding value described in the Examples. The term "step" is included in this term not only when it is an independent step, but also when it is not clearly distinguishable from other steps, as long as the function of the step is achieved.

[0013] In the contents shown in the drawings, the scale, shapes and lengths may be exaggerated for clarity. In the present specification, various measurements are performed based on the methods described in the Examples unless otherwise specified.

[0014] [First embodiment] [Photosensitive element] This embodiment is a photosensitive element comprising a support film and a photosensitive resin layer containing a photosensitive resin composition. Here, the photosensitive resin composition contains the following components based on the total solid content mass in the photosensitive resin composition: (A) alkali-soluble polymer: 30 to 70 mass %; (B) a compound having an ethylenically unsaturated bond: 20 to 60% by mass; and (C) biimidazole photopolymerization initiator: 4.0 to 10.0 mass%; Including, The content of structural units derived from benzyl (meth)acrylate in the component (A) is 40 mass% or more based on the entire component (A), The content of the compound having two ethylenically unsaturated bonds in one molecule in the component (B) is 80 mass % or more based on the entire component (B).

[0015] According to this embodiment, it is possible to form a resist pattern that is excellent in both the adhesion of the resist pattern and the formability of plated copper wiring. Furthermore, according to one preferred aspect of this embodiment, as described in the examples, it is possible to form a resist pattern that is excellent in resist pattern adhesion, plated copper wiring formability, independent fine line formability, and independent fine line remaining property after plating.

[0016] Hereinafter, in this specification, the above components (A) to (C) will be referred to simply as “component (A)” to “component (C).” The same applies to components (D) to (F) described below. The components (A) to (F) and the raw materials for these components may be used alone or in combination of two or more.

[0017] The photosensitive element includes a support film and a photosensitive resin layer containing a photosensitive resin composition. The photosensitive element may have other layers in addition to the support film and the photosensitive resin layer. Examples of the other layers include an intermediate layer provided between the support film and the photosensitive resin layer, a protective film provided on the opposite side of the photosensitive resin layer from the support film, and a release layer provided between the protective film and the photosensitive resin layer.

[0018] The photosensitive element is constructed, for example, by laminating a photosensitive resin layer directly on a support film, or by laminating a photosensitive resin layer on the support film via an intermediate layer. The photosensitive resin layer may be one layer or two or more layers.

[0019] From the viewpoint of easily and significantly achieving the effects of this embodiment, the photosensitive element is preferably a dry film resist or a transfer film, and more preferably a dry film resist.

[0020] <Support film> The support film is a layer or film for supporting the photosensitive resin layer, and is preferably a transparent film that transmits actinic rays.

[0021] Examples of materials for the transparent film include synthetic resins such as polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, etc. Among these, polyethylene terephthalate is preferred from the viewpoint of having appropriate flexibility and strength.

[0022] From the viewpoint of easily achieving excellent adhesion of the resist pattern, the absorbance of the support film at a wavelength of 365 nm is preferably 0.3 or less, more preferably 0.2 or less, even more preferably 0.1 or less, and most preferably 0.08 or less. The absorbance is 0 or more.

[0023] As the support film, it is preferable to use a film with few internal foreign matter, that is, a high-quality film.As the high-quality film, it is preferable to use a PET film synthesized using a Ti-based catalyst, a PET film with a small lubricant diameter and a small content, a PET film containing a lubricant only on one side of the film, a thin PET film, a PET film with a smoothing treatment on at least one side, a PET film with a roughening treatment such as plasma treatment on at least one side, etc.By using a high-quality film, the light to be exposed can be irradiated to the photosensitive resin layer without being blocked by internal foreign matter, and therefore, it is easy to realize the resist pattern with excellent resolution of the resist pattern.

[0024] The thickness of the support film is preferably 5 to 25 μm, more preferably 6 to 20 μm. The thinner the support film, the fewer the number of internal foreign bodies, and therefore the easier it is to prevent a decrease in the resolution of the resist pattern. On the other hand, if the film thickness is less than 5 μm, the film is likely to be stretched and deformed in the winding direction due to tension during the coating and winding manufacturing process, and is also likely to break due to minute scratches. As a result, the strength of the film is likely to be insufficient, and therefore wrinkles are likely to occur during lamination.

[0025] At least one surface of the support film may be subjected to a smoothing treatment using a calendar device, etc. This can reduce the surface roughness of one surface of the support film, particularly the surface that comes into contact with the photosensitive resin layer, and in this case, the effects of the present invention can be easily achieved.

[0026] The haze of the support film is preferably 0.01 to 1.5%, more preferably 0.01 to 1.2%, and even more preferably 0.01 to 0.95%, from the viewpoint of improving the parallelism of the light beam irradiated to the photosensitive resin layer and of facilitating excellent resolution.

[0027] <Photosensitive resin layer> The photosensitive resin layer contains a photosensitive resin composition. The photosensitive resin composition contains the following components based on the total solid content by mass in the photosensitive resin composition: (A) alkali-soluble polymer: 30 to 70 mass %; (B) a compound having an ethylenically unsaturated bond: 20 to 60% by mass; and (C) biimidazole photopolymerization initiator: 4.0 to 10.0 mass%; Includes. The photosensitive resin composition may optionally contain component (D) (another photopolymerization initiator) and component (E) (polymerization inhibitor), and may also optionally contain component (F) (antioxidant, stabilizer, base dye, plasticizer, etc.). Component (F) is a component other than components (A) to (E). Here, the "solid content" of the photosensitive resin composition corresponds to the components (A) to (F) contained in the photosensitive resin composition excluding the solvent.

[0028] <Component (A): Alkali-soluble polymer> The component (A) preferably has a monomer component consisting of a first monomer described below, and more preferably has a monomer component consisting of at least one type of the first monomer and at least one type of the second monomer described below. The content of the repeating unit of the component (A) is When only one type of alkali-soluble polymer is contained as component (A), this refers to the copolymerization ratio of the repeating units. When two or more alkali-soluble polymers are used as the component (A), the weighted average of the copolymerization ratio of the repeating units is calculated by using the ratio of the contents of each alkali-soluble polymer as the weight.

[0029] The first monomer is a monomer having a carboxyl group in the molecule and at least one polymerizable unsaturated group in the molecule. Examples of the first monomer include (meth)acrylic acid, fumaric acid, cinnamic acid, crotonic acid, itaconic acid, 4-vinylbenzoic acid, maleic anhydride, and maleic acid half ester. Among them, (meth)acrylic acid is preferred, and methacrylic acid is more preferred, from the viewpoint of easily achieving excellent adhesion and resolution of the resist pattern. In this specification, "(meth)acrylic acid" means acrylic acid or methacrylic acid, "(meth)acryloyl group" means acryloyl group or methacryloyl group, and "(meth)acrylate" means "acrylate" or "methacrylate".

[0030] The content of the first monomer is preferably 10 to 50 mass% based on the total mass of all monomer components. The content is preferably 10 mass% or more from the viewpoint of easily achieving excellent adhesion and resolution of the resist pattern, more preferably 15 mass% or more, even more preferably 18 mass% or more, even more preferably 21 mass% or more, particularly preferably 23 mass% or more, and most preferably 25 mass% or more. The content is preferably 50 mass% or less from the viewpoint of easily achieving excellent adhesion and resolution of the resist pattern, more preferably 35 mass% or less, even more preferably 30 mass% or less, particularly preferably 29 mass% or less, and most preferably 27 mass% or less. When two or more kinds of first monomers are used, the total content of each of them is preferably within the above range.

[0031] The second monomer is a monomer which is non-acidic and has at least one polymerizable unsaturated group in the molecule. The second monomer preferably contains a compound having an aromatic structure from the viewpoint of easily achieving excellent adhesion and resolution of the resist pattern. By containing such a compound as the second monomer, it is easy to suppress swelling during development of the photosensitive resin layer, and therefore it is easy to obtain a cured film having excellent adhesion and resolution of the resist pattern. The content of the structural unit derived from the compound having an aromatic structure is preferably 40 to 90 mass% based on the total mass of all monomer components. It is preferable to set the content to 40 mass% or more from the viewpoint of easily achieving excellent adhesion and resolution of the resist pattern, more preferably 45 mass% or more, even more preferably 50 mass% or more, even more preferably 55 mass% or more, and particularly preferably 60 mass% or more. It is preferable to set the content to 90 mass% or less from the viewpoint of excellent developability, and more preferably 85 mass% or less. When two or more kinds of compounds having an aromatic structure are used as the second monomer, the total content of each of them is preferably within the above range.

[0032] Examples of compounds having an aromatic structure include benzyl (meth)acrylate, styrene, methylstyrene, vinyltoluene, tert-butoxystyrene, acetoxystyrene, styrene dimer, styrene trimer and other styrene derivatives, 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]ethyl (meth)acrylate, and the like.

[0033] In this embodiment, the compound having an aromatic structure preferably contains benzyl (meth)acrylate. The content of benzyl (meth)acrylate may be 40% by mass or more, preferably 45% by mass or more, more preferably 50% by mass or more, more preferably 55% by mass or more, even more preferably 60% by mass or more, and particularly preferably 70% by mass or more, based on the total mass of all monomer components, from the viewpoint of easily achieving excellent plating copper wiring formability and independent thin line remaining property after plating. In addition, the content of benzyl (meth)acrylate is preferably 90% by mass or less, more preferably 85% by mass or less, from the viewpoint of easily achieving excellent adhesion of the resist pattern.

[0034] Two or more compounds having an aromatic structure may be used, and in this case, the compound may be a combination of styrene and benzyl (meth)acrylate. The total content of styrene and benzyl (meth)acrylate is preferably 50 to 90% by mass based on the total mass of all monomer components.

[0035] When the content of a compound having an aromatic structure (for example, benzyl (meth)acrylate) in the alkali-soluble polymer is large, the number of foreign matters in the photosensitive element is easily reduced.

[0036] In the case where the alkali-soluble polymer contains a copolymer that contains substantially only (meth)acrylic acid and benzyl (meth)acrylate as monomer components (in other words, the content of the monomer components derived from (meth)acrylic acid and the monomer components derived from benzyl (meth)acrylate in the copolymer is 95% by mass or more), the content of (meth)acrylic acid in the copolymer is preferably 15% by mass or more and 25% by mass or less, more preferably 17% by mass or more and 23% by mass or less, based on the total mass of all monomer components, from the viewpoint of the balance between developability, adhesion, and resolution. Benzyl (meth)acrylate is relatively hydrophilic compared to alkyl (meth)acrylate, styrene, etc., so that the above-mentioned excellent effects are easily obtained.

[0037] An example of a foreign matter in a photosensitive resin composition is shown in FIG. 1. In the figure, the photosensitive resin layer is indicated by the number "101", and the foreign matter is indicated by the number "110". Examples of the foreign matter 110 include a precipitate having a size of about several to several tens of μm (precipitate 111 shown in FIG. 1), or a precipitate having a size of about several μm as a nucleus with bubbles having a size of about several tens of μm (bubble 112 shown in FIG. 1) formed around it. The foreign matter can be observed visually or with an optical microscope.

[0038] It is expected that the development trend will be to include a relatively large amount of the (C) component in the photosensitive resin composition. On the other hand, if the content of the (C) component is high, the compatibility with other components in the photosensitive resin composition is likely to deteriorate, and therefore, it is thought that such foreign matter 110 will be generated in the photosensitive resin layer 101 during film formation. However, if the content of a compound having an aromatic structure (e.g., benzyl (meth)acrylate) in the (A) component is high, the compatibility between the (C) biimidazole photopolymerization initiator and the photosensitive resin composition is likely to improve. As a result, even if the photosensitive resin composition is designed to include a relatively large amount of the (C) component, it is thought that it is easy to prevent the generation of the (C) component in the photosensitive resin composition, and therefore, the number of foreign matters will be easy to reduce.

[0039] It is also preferred that the second monomer contains a compound having a hydroxyl group. By having a structural unit derived from such a compound, it becomes easier to control the developability of the photosensitive resin layer, and therefore it is easy to obtain a cured film having excellent adhesion and resolution of the resist pattern. The second monomer may contain both a compound having an aromatic structure and a compound having a hydroxyl group.

[0040] The compound having a hydroxy group is preferably a hydroxyalkyl (meth)acrylate. As the hydroxyalkyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate are preferred, and 2-hydroxyethyl methacrylate is more preferred. These are relatively easy to obtain, and yet, the developability is easy to control, and it is easy to realize a resist pattern having excellent adhesion and resolution.

[0041] From the viewpoints of easily achieving excellent adhesion and developability of a resist pattern, the content of the compound having a hydroxy group in the component (A) is preferably from 1.0 to 20 mass%, more preferably from 1 to 10 mass%, and even more preferably from 1 to 6 mass%, based on the total mass of all monomer components. When two or more types of compounds having a hydroxyl group are used, the total content of each of them is preferably within the above range.

[0042] The second monomer may further include a polymerizable compound different from either a compound having an aromatic structure or a compound having a hydroxyl group. Examples of polymerizable compounds different from either a compound having an aromatic structure or a compound having a hydroxyl group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, isobornyl (meth)acrylate, and nonylphenoxy polyethylene glycol. (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, phenoxyethyl (meth)acrylate, ethyl carbitol (meth)acrylate, methoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, and 3,3,5-trimethylcyclohexyl (meth)acrylate; esters of vinyl alcohol such as vinyl acetate; and (meth)acrylonitrile.

[0043] The weight average molecular weight Mw of the component (A) is preferably 10,000 to 60,000. From the viewpoint of easily realizing flexibility, resolution, and developability of the resist pattern, it is preferable that the weight average molecular weight Mw is 60,000 or less, and from the same viewpoint, it is more preferable that it is 55,000 or less, and even more preferable that it is less than 50,000. From the same viewpoint, the weight average molecular weight Mw is preferably 10,000 or more, more preferably 14,000 or more, and even more preferably 25,000 or more.

[0044] The polydispersity of the component (A) (weight average molecular weight Mw / number average molecular weight Mn) is preferably from 1.0 to 6.0, more preferably from 1.0 to 5.0, even more preferably from 1.0 to 4.0, and particularly preferably from 1.0 to 3.0.

[0045] As described above, the (A) component may be used alone or in combination of two or more. When two or more types are used in combination, it is preferable that the molecular weights and polydispersities of the monomers in the multiple (A) components are selected so that the weighted average value, when the content ratio is treated as the weight, falls within the above range.

[0046] The (A) component may be synthesized by mixing one or more of the above monomers and a radical polymerization initiator in a solution diluted with a solvent, and then heating and stirring the mixture. The solvent referred to here is, for example, acetone, methyl ethyl ketone, isopropanol, etc., and the radical polymerization initiator referred to here is, for example, benzoyl peroxide, azoisobutyronitrile, etc. The (A) component may be synthesized while dropping a part of the mixture into the reaction solution. After the (A) component is synthesized, the solvent may be further added to adjust the concentration to the desired level. As a method for synthesizing the (A) component, bulk polymerization, suspension polymerization, or emulsion polymerization may be used in addition to solution polymerization. The (A) component may also be synthesized by living radical polymerization.

[0047] The content of the component (A) relative to the total solid content of the photosensitive resin composition is 30% by mass or more, optionally 35% by mass or more, optionally 40% by mass or more, optionally 45% by mass or more, optionally 50% by mass or more, and is 70% by mass or less, optionally 65% ​​by mass or less, optionally 60% by mass or less.

[0048] It is preferable to set the content ratio of component (A) to the total solid content mass of the photosensitive resin composition to 70 mass % or less from the viewpoint of appropriately controlling the development time, and it is preferable to set the content ratio of component (A) to 30 mass % or more from the viewpoint of suppressing bleeding of the photosensitive resin layer from the edge faces of the film.

[0049] <Component (B): Compound having an ethylenically unsaturated bond> The component (B) is a compound having at least one ethylenically unsaturated bond in one molecule.

[0050] The component (B) preferably contains a compound having two or more ethylenically unsaturated bonds in one molecule. For example, the component (B) contains a compound having two ethylenically unsaturated bonds in one molecule. However, the component (B) may contain a compound having three ethylenically unsaturated bonds in one molecule, and may also contain a compound having four, five, or six ethylenically unsaturated bonds in one molecule.

[0051] From the viewpoint of excellent independent thin line forming ability, the content of the compound having two ethylenically unsaturated bonds in one molecule in component (B) may be 80% by mass or more, preferably 85% by mass or more, and more preferably 90% by mass or more, based on the entire component (B). Also, the content may be 100% by mass or less than 100% by mass based on the entire component (B).

[0052] In the component (B), an example of a compound having two ethylenically unsaturated bonds in one molecule is a compound having a bisphenol skeleton. The term "compound having a bisphenol skeleton" as used herein also includes compounds having a hydrogenated bisphenol skeleton.

[0053] The (B) component preferably contains a compound containing a (meth)acryloyl group (also referred to in this specification as a "(meth)acrylate compound"), and more preferably contains a di- or higher functional (meth)acrylate compound (a compound having two or more (meth)acryloyl groups in one molecule).

[0054] When the (B) component contains a (meth)acrylate compound, it may contain only a difunctional (meth)acrylate compound, or it may contain a difunctional (meth)acrylate compound and a trifunctional or higher (meth)acrylate compound. The (meth)acrylate compound may contain, for example, a tetrafunctional, pentafunctional, or hexafunctional (meth)acrylate compound.

[0055] When the (B) component contains a (meth)acrylate compound, the content of the bifunctional (meth)acrylate compound may be 80% by mass or more, preferably 85% by mass or more, and more preferably 90% by mass or more, based on the total mass of the (B) component, from the viewpoint of excellent independent thin line forming ability. Moreover, the content may be 100% by mass or less than 100% by mass based on the total mass of the (B) component.

[0056] When the component (B) contains a compound having three or more ethylenically unsaturated bonds in one molecule, the content of the compound may be 20% by mass or less, 15% by mass or less, or 10% by mass or less based on the total weight of the component (B), from the viewpoint of easily achieving excellent adhesion and developability of the resist pattern. Also, the content may be 1% by mass or more, or 5% by mass or more based on the total weight of the component (B).

[0057] When the component (B) contains a tri- or higher functional (meth)acrylate compound, from the viewpoint of tending to provide excellent adhesion and developability of a resist pattern, the content of the compound may be no more than 20 mass%, or no more than 15 mass%, or no more than 10 mass%, relative to the total mass of the component (B).

[0058] Examples of the bifunctional (meth)acrylate compound include Alkyl di(meth)acrylate, 1,3-bis(meth)acryloyloxy-2-propanol, The following general formula (I): [ka] {where, R 1 are each independently a hydrogen atom or a methyl group; X 1 O and Y 1 Each O is independently an oxyalkylene group having 2 to 4 carbon atoms, m1, m2, and n1 are independently an integer of 0 to 40, m1+m2 is 1 to 40, and n1 is 0 to 20.} A polyalkylene glycol di(meth)acrylate represented by the formula: tricyclodecanol di(meth)acrylate, The following general formula (II): [ka] {where, R 2 are each independently a hydrogen atom or a methyl group; X 2 O and Y 2 Each O is independently an oxyethylene group or an oxypropylene group, m3, m4, n2, and n3 are independently an integer of 0 to 40, m3+m4 is 1 to 40, and n2+n3 is 0 to 20.} and bisphenol A di(meth)acrylate represented by the following formula:

[0059] The polyalkylene glycol di(meth)acrylate represented by the formula (I) is 1 = methyl group, m1+m2=6 (average value), n1=12 (average value), X 1 O is an oxyethylene group, Y 1 Examples include a vinyl compound in which O is an oxypropylene group (manufactured by Resonac, product name "FA-024M").

[0060] The bisphenol A type di(meth)acrylate compound represented by the general formula (II) is, for example, BPE-200 (R 2 = methyl group, X 2 O = oxyethylene group, m3 + m4 = 4, n2 = n3 = 0), BPE-500 (R 2 = methyl group, X 2 O = oxyethylene group, m3 + m4 = 10, n2 = n3 = 0), BPE-900(R 2 = methyl group, X 2 O = oxyethylene group, m3 + m4 = 17, n2 = n3 = 0) (all products of Shin-Nakamura Chemical Co., Ltd.), FA-321M (R 2 = methyl group, X 2 O = oxyethylene group, m3 + m4 = 10, n2 = n3 = 0), FA-P321M(R 2 = methyl group, X 2O = oxypropylene group, m3 + m4 = 10, n2 = n3 = 0) (above, product names manufactured by Resonac), FA-P323M(R 2 = methyl group, X 2 O=oxypropylene group, Y 2 O=oxyethylene group, m3+m4=4, n2+n3=30) (all of the above are product names manufactured by Resonac Corporation).

[0061] From the viewpoint of easily achieving excellent adhesion, resolution, plated copper wiring formability, and independent fine line formability of the resist pattern, the component (B) preferably contains a bisphenol A type di(meth)acrylate compound represented by the general formula (II). The content of the compound is preferably 1% by mass or more, more preferably 20% by mass or more, even more preferably 50% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more, based on the entire component (B). Since the compound has a high aromatic ring ratio, the use of such a compound provides good compatibility with benzyl (meth)acrylate, and therefore the plated copper wiring formability and independent fine line formability are easily improved.

[0062] In the compound represented by the above general formula (II), from the viewpoint of easily achieving excellent adhesion and resolution of a resist pattern, the average value of n2+n3+m3+m4 of the compound contained in the photosensitive resin composition is preferably 20 or less, and more preferably 15 or less. In addition, the average value of n2+n3+m3+m4 of the compound contained in the photosensitive resin composition may be 2 or more, preferably more than 4, and more preferably more than 10. It is further preferable that the bisphenol A di(meth)acrylate compound contains the above-mentioned bisphenol A di(meth)acrylate in which the average value of n2+n3+m3+m4 is 10 or less, and the above-mentioned bisphenol A di(meth)acrylate in which the average value of n2+n3+m3+m4 is 15 or more, from the viewpoint of excellent independent thin line formability. The number of structural units of oxyethylene groups or oxypropylene groups indicates an integer value in a single molecule, and indicates a rational number which is an average value in an aggregate of a plurality of molecules.

[0063] Commercially available bifunctional (meth)acrylate compounds include, for example, NK Ester (registered trademark) A-HD-N, A-NOD-N, A-DOD-N, A-NPG, 701A, A-200, A-400, A-600, A-1000, APG-200, APG-400, APG-700, A-PTMG65, A-DCP, ABE-300, A-BPE-4, A-BPE-10, A-BPE-20, HD-N, NOD-N, DOD-N, NPG, 701, 2G, 3G, 4G, 9G, and 14. G, 23G, 9PG, DCP, BPE-80N, BPE-100, BPE-200, BPE-500, BPE-900, BPE-1300N, NK Oligo (registered trademark) UA-4200, UA-160TM, UA-290TM, UA-W2A, UA-4400, UA-122P, U-200PA (all manufactured by Shin-Nakamura Chemical Co., Ltd.), Light Acrylate (registered trademark) 3EG-A, 4EG-A, 9EG-A, 14EG-A, PTMGA-250, NP-A, MPD-A, 1.6HX-A, 1.9ND-A, DCP-A, BP-4EAL, BP-4PA, HPP-A, Light Ester G-201P (all manufactured by Kyoeisha Chemical Co., Ltd.), Fancryl (registered trademark) FA-124AS, FA-023M, FA-121M, FA-124M, FA-125M, FA-129AS, FA-137M, FA-220M, FA-222A, and FA-240 A, FA-240M, FA-320M, FA-3218M, FA-321A, FA-321M, FA-324A, FA-731A, FA-P240A, FA-P270A, FA-PTG9A, FA-PTG9M, FA-PTG28A, FA-PTG49A (all manufactured by Resonac), DPGDA, HDDA, TPGDA, EBECRYL 145, EBECRYL 150, PEG400DA, EBECRYL 11, IRR 214-K, EBECRYL 130, EBECRYL PEG200DMA (manufactured by Daicel-Allnex), SR212, SR213, SR230, SR238F, SR259, SR268, SR272, SR306H, SR344, SR349, SR508, CD560, CD561, CD564, SR601, SR602, SR610, SR833S, SR9003, SR9045, SR9209, SR205, SR206, SR209, SR210, SR214, SR231, SR239, SR248, SR252, SR297, SR348, SR480, CD540, CD541, CD542, SR603, SR644, SR9036 (manufactured by Arkema), KAYARAD (registered trademark) Examples include NPGDA, PEG400DA, FM-400, R-167, HX-220, HX-620, R-551, R-712, R-604, and R-684 (all manufactured by Nippon Kayaku Co., Ltd.).

[0064] Examples of trifunctional or higher (meth)acrylate compounds include trimethylolpropane tri(meth)acrylate, glycerin tri(meth)acrylate, isocyanuric acid tri(meth)acrylate, pentaerythritol (tri / tetra)(meth)acrylate, ditrimethylolpropane (tetra / penta / hexa)(meth)acrylate, and dipentaerythritol (tetra / penta / hexa)(meth)acrylate.

[0065] Trifunctional or higher (meth)acrylate compounds are an alcohol having, as a central skeleton, three or more groups to which an alkylene oxide group can be added within the molecule, and to which an alkylene oxide group such as an ethylene oxide group, a propylene oxide group or a butylene oxide group has been added; (Meth)acrylic acid, The compound may be a compound obtained by forming a (meth)acrylate from Examples of such compounds include alkylene oxide-modified tri(meth)acrylate of trimethylolpropane, alkylene oxide-modified tri(meth)acrylate of glycerin, alkylene oxide-modified pentaerythritol (tri / tetra)(meth)acrylate, alkylene oxide-modified ditrimethylolpropane (tetra / penta / hexa)(meth)acrylate, alkylene oxide-modified dipentaerythritol (tetra / penta / hexa)(meth)acrylate, alkylene oxide-modified isocyanuric acid tri(meth)acrylate, and the like.

[0066] The tri- or higher functional (meth)acrylate compound may contain alkylene oxide-modified pentaerythritol (tri / tetra)(meth)acrylate from the viewpoint of excellent developability.

[0067] Commercially available trifunctional or higher (meth)acrylate compounds include, for example, NK Ester (registered trademark) A-TMPT, A-TMPT-9EO, AT-20E, A-GLY-3E, A-GLY-9E, A-GLY-20E, A-9300, A-9200YN, A-TMM-3, A-TMM-3L, A-TMM-3LM-N, A-TMMT, ATM-35E, AD-TMP, A-DPH, and A-955. 0, A-DPH-12E, TPOA-50, NK Oligo (registered trademark) UA-7100, UA-1100H, U-6LPA, UA-33H, U-10HA, U-10PA, U-15HA (all manufactured by Shin-Nakamura Chemical Co., Ltd.), Light Acrylate (registered trademark) TMP-A, cPE-3A, PE-4A, DPE-6A (all manufactured by Kyoeisha Chemical Co., Ltd.), FA-731A (manufactured by Resonac Co., Ltd.), TMPTA, EBECRYL 160S, OTA 480, PETIA, PETRA, EBECRYL 40, PETA, EBECRYL 140, EBECRYL 1140, EBECRYL 1142, DPHA, EBECRYL 895, EBECRYL 896, EBECRYL TMPTMA (all manufactured by Daicel-Allnex), SR351S, SR368, SR415, SR444, SR454, SR492, SR499, CD501, SR502, SR9020, D9021, SR9035, SR295, SR355, SR399, SR494, SR9041 (all manufactured by Arkema), KAYARAD (registered trademark) Examples include GPO-303, TMPTA, THE-330, TPA-330, PET-30, T-1420(T), RP-1040, DPHA, DPEA-12, D-310, and DPCA-20 (all manufactured by Nippon Kayaku Co., Ltd.).

[0068] In light of the above, an example of the component (B) that can be used in this embodiment is as follows: However, the component (B) used in this embodiment is not limited to only the following compound. Dimethacrylate of polyethylene glycol in which an average of two moles of ethylene oxide are added to each end of bisphenol A (manufactured by Shin-Nakamura Chemical Co., Ltd., product name BPE-200); Dimethacrylate of polyethylene glycol in which an average of 5 moles of ethylene oxide are added to each end of bisphenol A (manufactured by Shin-Nakamura Chemical Co., Ltd., product name BPE-500); Dimethacrylate of polyethylene glycol in which an average of 2 moles of propylene oxide and an average of 15 moles of ethylene oxide are added to both ends of bisphenol A; Tetramethacrylate, in which an average of one mole of ethylene oxide is added to each of the four ends of pentaerythritol; Hexamethacrylate in which an average of two moles of ethylene oxide are added to each of the six terminals of dipentaerythritol; and A dimethacrylate of polyethylene glycol in which an average of 5 moles of ethylene oxide are added to each end of hydrogenated bisphenol A.

[0069] The content of the (B) component relative to the total solid content in the photosensitive resin composition is 20% by mass or more, preferably 25% by mass or more, more preferably 30% by mass or more, and even more preferably 35% by mass or more, from the viewpoints of excellent sensitivity, tackiness, and followability, and is 60% by mass or less, preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 42% by mass or less, from the viewpoints of excellent edge fusion resistance, tackiness, and resolution. The edge fusion resistance referred to here means a property of suppressing the overflow of the resist during storage of the photosensitive element roll, and in this case, the smaller the amount of overflow, the more preferable. Also, the tackiness referred to here means the adhesiveness of the photosensitive resin composition.

[0070] From the viewpoint of excellent edge fusion property, tackiness, and resolution, the value of the content of the (A) component relative to the content of the (B) component (i.e., the value of the (A) component content / (B) component content) is preferably 1.6 or less, more preferably 1.5 or less, and even more preferably 1.4 or less. This value is preferably 0.7 or more, more preferably 0.8 or more, even more preferably 0.9 or more, and particularly preferably 1.0 or more.

[0071] The number of ethylenically unsaturated bonds per 100 g of solid content of the photosensitive resin composition is preferably 0.1 to 0.3 mol. When the number is 0.1 mol or more, it is easy to prevent the photosensitive resin component from eluting from the cured resist pattern in the water washing step after development, and thus the water washing step from being contaminated. When the number is 0.3 mol or less, the cured resist pattern is less likely to chip or fall off in the water washing step after development, and therefore it is easy to prevent the water washing step from being contaminated.

[0072] The number of ethylenically unsaturated bonds per 100 g of solid content of the photosensitive resin composition is preferably 0.1 mol or more, more preferably 0.11 mol or more, even more preferably 0.12 mol or more, and particularly preferably 0.13 mol or more. The number of such ethylenically unsaturated bonds is preferably 0.3 mol or less, more preferably 0.28 mol or less, even more preferably 0.25 mol or less, particularly preferably 0.22 mol or less, 0.20 mol or less, or 0.18 mol or less, and most preferably 0.15 mol or less.

[0073] The number of ethylenically unsaturated bonds per 100 g of solid content in the photosensitive resin composition is preferably 0.1 to 0.25 mol, more preferably 0.1 to 0.2 mol, still more preferably 0.11 to 0.2 mol, and particularly preferably 0.11 to 0.15 mol.

[0074] <Component (C): Biimidazole photopolymerization initiator> The component (C) is a photopolymerization initiator having a biimidazole structure. The content of the (C) component is 4.00% by mass or more based on the total solid content mass of the photosensitive resin composition, and from the viewpoint of easily achieving excellent adhesion of the resist pattern, it is preferably 4.25% by mass or more or 4.50% by mass or more, more preferably 4.75% by mass or more, even more preferably 5.00% by mass or more, even more preferably 5.25% by mass or more, particularly preferably 5.75% by mass or more, and most preferably 6.00% by mass or more. Also, from the viewpoint of easily reducing the number of foreign matters, the content is preferably 10.0% by mass or less, more preferably 9.00% by mass or less, and even more preferably 8.00% by mass or less.

[0075] An example of the component (C) is a lophine dimer, that is, a dimer of a compound having a lophine structure (a compound having a 2,4,5-triarylimidazole skeleton). The lophine dimer, i.e., the dimer of 2,4,5-triarylimidazole, includes 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer {alias: 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole}, 2,2',5-tris-(o-chlorophenyl)-4-(3,4-dimethoxyphenyl)-4',5'-diphenylbiimidazole, 2,4-bis-(o-chlorophenyl)-5-(3,4-dimethoxyphenyl)-diphenylbiimidazole, 2,4,5-tris-(o-chlorophenyl)-5-(3,4-dimethoxyphenyl)-diphenylbiimidazole, 2-(o-chlorophenyl)-bis-4,5-(3,4-dimethoxyphenyl)-biimidazole, 2,2'-bis-(2-fluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole, 2,2'-bis-(2,3-difluoromethylphenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole, 2,2'-bis-(2,4-difluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole 2,2'-bis-(2,5-difluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole, 2,2'-bis-(2,6-difluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole, 2,2'-bis-(2,3,4-trifluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole, 2,2'-bis-(2,3,5-trifluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole, 2,2'-bis-(2,3,6-trifluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole, 2,2'-bis-(2,4,5-trifluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole, 2,2'-bis-(2,4,6-trifluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole, 2,2'-bis-(2,3,4,5-tetrafluorophenyl)-4,4',5,Examples of such compounds include 5'-tetrakis-(3-methoxyphenyl)-biimidazole, 2,2'-bis-(2,3,4,6-tetrafluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole, and 2,2'-bis-(2,3,4,5,6-pentafluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole.

[0076] From the standpoint of tending to achieve excellent adhesion and resolution of the resist pattern, the component (C) preferably contains a lophine dimer, and in particular it is more preferable for it to contain 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer.

[0077] <Component (D): Other photopolymerization initiators> Examples of the component (D) include N-aryl-α-amino acid compounds, quinone compounds, aromatic ketone compounds, anthracene derivatives, acetophenone compounds, acylphosphine oxide compounds, benzoin compounds, benzoin ether compounds, dialkyl ketal compounds, thioxanthone compounds, dialkylaminobenzoic acid ester compounds, oxime ester compounds, acridine compounds, pyrazoline derivatives, N-arylamino acid ester compounds, coumarin derivatives, and halogen compounds.

[0078] Examples of aromatic ketone compounds include benzophenone compounds. Examples of benzophenone compounds include benzophenone, Michler's ketone [4,4'-bis(dimethylamino)benzophenone], 4-methoxy-4'-dimethylaminobenzophenone, etc. As the aromatic ketone compound, 4,4'-bis(diethylamino)benzophenone is preferred from the viewpoint of excellent sensitizing effect and adhesion.

[0079] That is, in the photosensitive resin composition, the component (D) preferably contains at least one selected from the group consisting of a benzophenone compound, a pyrazoline compound, an anthracene compound, and a coumarin compound.

[0080] In the present specification, the term "anthracene derivative" refers to both anthracene and compounds derived therefrom. Examples of anthracene derivatives include anthracene, 9,10-dialkoxyanthracene, 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, 9,10-dibutoxyanthracene, 9,10-diphenylanthracene, 2-ethylanthraquinone, octaethylanthraquinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone, 2-phenylanthraquinone, 2,3-diphenylanthraquinone, 1-chloroanthraquinone, and 10-phenyl-9-anthraceneboronic acid. From the viewpoint of excellent sensitizing effect and adhesion, 9,10-dibutoxyanthracene, 9,10-diphenylanthracene, and 10-phenyl-9-anthraceneboronic acid are preferred, and 9,10-diphenylanthracene and 10-phenyl-9-anthraceneboronic acid are particularly preferred.

[0081] As the pyrazoline derivative, from the viewpoint of excellent adhesion and rectangularity of the resist pattern, 1-phenyl-3-(4-tert-butyl-styryl)-5-(4-tert-butyl-phenyl)-pyrazoline, 1-phenyl-3-(4-biphenyl)-5-(4-tert-butyl-phenyl)-pyrazoline, 1-phenyl-3-(4-biphenyl)-5-(4-tert-octyl-phenyl)-pyrazoline, and 1-phenyl-3-(4-methoxystyryl)-5-(4-methoxyphenyl)-pyrazoline are preferred.

[0082] When the photosensitive resin composition contains the component (D), from the viewpoint of excellent storage stability, it preferably contains any one of a benzophenone compound, a pyrazoline compound, an anthracene compound, and a coumarin compound, and more preferably contains any one of a benzophenone compound and a pyrazoline compound.

[0083] The content of the component (D) is preferably 0 to 0.5 mass %, more preferably 0 to 0.1 mass %, further preferably 0 to 0.05 mass %, particularly preferably 0 to 0.025 mass %, based on the total solid content mass of the photosensitive resin composition. By adjusting the content of the component (D) within the above range, it is easy to reduce the absorbance in a region other than the exposure wavelength, and therefore it is easy to improve the storage stability.

[0084] <Component (E): Polymerization inhibitor> Examples of the component (E) include phenothiazine, p-methoxyphenol, hydroquinone, pyrogallol, naphthylamine, tert-butylcatechol, cuprous chloride, 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], nitrosophenylhydroxyamine aluminum salt (e.g., aluminum salt with 3 moles of nitrosophenylhydroxylamine added), diphenylnitrosamine, etc. Among them, triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate] or aluminum salt with 3 moles of nitrosophenylhydroxylamine added is preferred.

[0085] From the standpoint of tending to achieve excellent adhesion of the resist pattern and excellent storage stability, the component (E) preferably contains any of phenothiazine, p-methoxyphenol, tert-butylcatechol, or 2,6-di-tert-butyl-p-cresol, and more preferably contains phenothiazine and / or tert-butylcatechol.

[0086] From the viewpoint of achieving excellent resist pattern resolution and plated copper wiring formability, the content of the component (E) is preferably 10 to 5000 ppm, more preferably 10 to 1000 ppm, even more preferably 50 to 1000 ppm, and particularly preferably 50 to 500 ppm, based on the total solids mass of the photosensitive resin composition.

[0087] <(F) Other Ingredients> The photosensitive resin composition may contain component (F) as desired. Examples of the component (F) include a base dye, an antioxidant, a stabilizer, a color-forming dye, and a plasticizer. The photosensitive resin composition may also contain various solvents as component (F).

[0088] Base dye Examples of base dyes include Diamond Green [CAS number (hereinafter the same): 633-03-4] (e.g., Aizen Diamond Green GH, trade name, manufactured by Hodogaya Chemical Co., Ltd.), Fuchsin [632-99-5], Methyl Violet [603-47-4], Methyl Green [82-94-0], Victoria Blue B [2580-56-5], Basic Blue 7 [2390-60-5] (e.g., Aizen Victoria Pure Blue BOH, trade name, manufactured by Hodogaya Chemical Co., Ltd.), Rhodamine B [81-88-9], Rhodamine 6G [989-38-8], Basic Yellow 2 [2465-27-2], etc. Among them, Diamond Green is preferable from the viewpoint of improving colorability, hue stability, and exposure contrast.

[0089] The content of the base dye is preferably 0.001 to 3 mass%, more preferably 0.01 to 2 mass%, and even more preferably 0.04 to 1 mass%, based on the total solid content mass of the photosensitive resin composition. From the viewpoint of obtaining good coloring properties, the content of the base dye is preferably equal to or more than the above lower limit, while from the viewpoint of maintaining the sensitivity of the photosensitive resin layer, the content of the base dye is preferably equal to or less than the above upper limit.

[0090] Antioxidants Examples of the antioxidant include triphenyl phosphite (e.g., ADEKA Corporation, trade name: TPP), tris(2,4-di-tert-butylphenyl)phosphite (e.g., ADEKA Corporation, trade name: 2112), tris(mononylphenyl)phosphite (e.g., ADEKA Corporation, trade name: 1178), bis(mononylphenyl)-dinonylphenyl phosphite (e.g., ADEKA Corporation, trade name: 329K), and the like.

[0091] The content of the antioxidant is preferably 0.01 to 0.8% by mass, more preferably 0.01 to 0.3% by mass, based on the total solid content mass of the photosensitive resin composition. The content of the antioxidant is preferably equal to or more than the lower limit from the viewpoint of favorably expressing the hue stability of the resist pattern and improving the sensitivity of the photosensitive resin layer. On the other hand, the content of the antioxidant is preferably equal to or less than the upper limit from the viewpoint of favorably expressing the hue stability while suppressing the color development of the resist pattern.

[0092] Stabilizers The stabilizer can be used from the viewpoint of improving the thermal stability of the photosensitive resin composition. Examples of the stabilizer include at least one of an alkylene oxide compound having a glycidyl group and a benzotriazole compound.

[0093] Examples of alkylene oxide compounds having a glycidyl group include neopentyl glycol diglycidyl ether (e.g., Epolight 1500NP manufactured by Kyoeisha Chemical Co., Ltd.), nonaethylene glycol diglycidyl ether (e.g., Epolight 400E manufactured by Kyoeisha Chemical Co., Ltd.), bisphenol A-propylene oxide 2-mol adduct diglycidyl ether (e.g., Epolight 3002 manufactured by Kyoeisha Chemical Co., Ltd.), and 1,6-hexanediol diglycidyl ether (e.g., Epolight 1600 manufactured by Kyoeisha Chemical Co., Ltd.).

[0094] Examples of the benzotriazole compound include carboxylbenzotriazole, 1,2,3-benzotriazole, 1-chloro-1,2,3-benzotriazole, 1-(N,N-bis(2-ethylhexyl)aminomethyl)-1,2,3-benzotriazole, 1-(N,N-bis(2-ethylhexyl)aminomethyl)-1,2,3-tolyltriazole, 1-(N,N-bis-2-hydroxyethyl)aminomethyl)-1,2,3-benzotriazole, and 1-(N,N-bis(2-ethylhexyl)aminomethyl)-5-carboxy-1,2,3-benzotriazole.

[0095] The total content of the antioxidant, the alkylene oxide compound having a glycidyl group, and the benzotriazole compound in the photosensitive resin composition is preferably 0.001 to 3 mass %, and more preferably 0.05 to 1 mass %, based on the total solid content mass of the photosensitive resin composition.

[0096] Color-developing dyes The photosensitive resin composition may contain a color-developing dye that develops color upon irradiation with light. As a color-developing dye, for example, a combination of a leuco dye and a halogen compound is known. As a leuco dye, for example, tris(4-dimethylamino-2-methylphenyl)methane [leuco crystal violet], tris(4-dimethylamino-2-methylphenyl)methane [leucomalachite green], etc. can be mentioned. As a halogen compound, for example, amyl bromide, isoamyl bromide, isobutylene bromide, ethylene bromide, diphenylmethyl bromide, benzal bromide, methylene bromide, tribromomethylphenyl sulfone, carbon tetrabromide, tris(2,3-dibromopropyl)phosphate, trichloroacetamide, amyl iodide, isobutyl iodide, 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane, hexachloroethane, etc. can be mentioned.

[0097] Plasticizer The photosensitive resin composition may contain additives such as plasticizers in the photosensitive resin layer. Examples of such additives include phthalates such as diethyl phthalate, o-toluenesulfonic acid amide, p-toluenesulfonic acid amide, tributyl citrate, triethyl citrate, triethyl acetyl citrate, tri-n-propyl acetyl citrate, tri-n-butyl acetyl citrate, polypropylene glycol, polyethylene glycol, polyethylene glycol alkyl ether, polypropylene glycol alkyl ether, etc.

[0098] <Configuration of photosensitive resin layer> The thickness of the photosensitive resin layer is preferably 3 to 100 μm, and specific preferred upper limits of the thickness include 7 μm, 15 μm, 25 μm, 40 μm, and 60 μm. In one embodiment, the preferred upper limit of the thickness is 50 μm. The closer the thickness is to 3 μm, the easier it is to improve the resolution, and the closer it is to 100 μm, the easier it is to improve the film strength. Thus, the thickness of the photosensitive resin layer can be appropriately selected depending on the use of the photosensitive element, and the use of the resist pattern or final product obtained using the photosensitive element. When the formed resist pattern is used in a plating formation process, the thickness is preferably 10 to 30 μm, more preferably 15 to 27 μm.

[0099] In this embodiment, the absorbance (Y) at a wavelength of 365 nm when the photosensitive resin layer has a film thickness of 25 μm is 0.35 or less. This makes it easy to obtain excellent storage stability and rectangularity of the resist pattern, and excellent adhesion of the resist pattern. From the same viewpoint, the absorbance is preferably 0.3 or less, more preferably 0.2 or less, even more preferably 0.18 or less, and particularly preferably 0.16 or less. The absorbance may be 0 or more, and from the viewpoint of obtaining a photosensitive resin layer resin composition having good photoreactivity and excellent sensitivity, it is preferably 0.11 or more.

[0100] In general, the absorbance of the photosensitive resin layer can be measured by placing the substrate on which the photosensitive resin layer is formed on the reference side and using a spectrophotometer. In addition, in general, the absorbance can also be measured with reference to JIS K 0115 (2004). When using a spectrophotometer, the absorbance of the photosensitive resin layer can also be calculated by converting the result of measurement using only the substrate as a reference. In the case of a photosensitive element described later, a support film can be used as the substrate. The absorbance measured by the above method is a value derived including the amount of light scattered by the photosensitive resin layer and the substrate. The "absorbance" in this embodiment is a value derived using the method described in the <absorbance> section of the examples.

[0101] In one embodiment, The photosensitive resin composition contains 5.0% by mass or more of component (C) based on the total solid content by mass of the photosensitive resin composition, The photosensitive resin layer has an absorbance (Y) of 0.35 or less at a wavelength of 365 nm when the layer has a thickness of 25 μm; It is preferable that the contribution (X) of the absorbance of the (C) component to the absorbance (Y) is 40% or more.

[0102] In this embodiment, the contribution (X) is expressed by the following formula (1): X(%)= 100×εc / absorbance of photosensitive resin layer (Y) (1) ε: Change in absorbance per 1 mass% of component (C) c: Content (mass%) of component (C) in the total solid components of the photosensitive resin composition It is calculated as follows.

[0103] ε can be calculated by the following method. Photosensitive resin compositions were prepared by adding different amounts of the (C) component to 100 parts by mass of the total of the (A) and (B) components, and each was applied to a substrate to a film thickness of 25 μm, and the absorbance of the resulting photosensitive resin layer was measured. The results were plotted with the content (mass%) of the (C) component on the X-axis and the absorbance (Y) of the photosensitive resin layer on the Y-axis, based on the total solid mass of the photosensitive resin composition. The data thus obtained was linearly approximated to obtain a straight line with a specified slope. The slope of this straight line corresponds to the change ε ​​in absorbance per 1 mass% of the (C) component at that content. The component (A) used in this case preferably contains methacrylic acid, styrene, benzyl methacrylate, 2-hydroxyl methacrylate, and methyl methacrylate in any ratio. The component (B) preferably is a bisphenol A di(meth)acrylate such as FA-321M. These components have low absorbance at 365 nm, and are therefore suitable for accurately measuring the absorbance change value ε per 1 mass % of the component (C).

[0104] From the viewpoint of excellent storage stability, the contribution (X) is preferably 45% or more, more preferably 55% or more, even more preferably 65% ​​or more, and particularly preferably 85% or more. It is considered that the larger the value (X), the easier it is to suppress the sensitizing effect of additives other than the component (C), and therefore the easier it is to reduce the reactivity to light with long wavelengths such as yellow light, and thus the storage stability tends to improve.

[0105] Examples of means for increasing the contribution (X) include increasing the content of the component (C), decreasing the content of the component (D), and decreasing the content of other components that have absorption at 365 nm.

[0106] When the photosensitive resin composition contains a plurality of components (C), the contribution (X) can be calculated as follows. That is, when the component (C) contains the components (C-1) to (Cn) (n is an integer of 2 or more), the change in absorbance per 1 mass% is ε1 to ε n , and thus derive the contributions (X-1) to (Xn). The sum of the obtained contributions (X-1) to (Xn) is treated as the contribution (X) in this embodiment.

[0107] <Protective film> The photosensitive element may include a protective film. The support film, the photosensitive resin layer, and the protective film may be laminated in this order. The protective film can be laminated on the photosensitive resin layer side of the laminate of the support film and the photosensitive resin layer, and functions as a cover.

[0108] When the adhesive strength between the photosensitive resin layer and the protective film is sufficiently smaller than that between the photosensitive resin layer and the support film, the protective film can be easily peeled off from the photosensitive resin layer. For example, a polyethylene film, a polypropylene film, an oriented polypropylene film, a polyester film, etc. can be preferably used as the protective film. A release layer may be provided on the surface of the protective film.

[0109] The thickness of the protective film is preferably 10 to 100 μm, more preferably 10 to 50 μm. Examples of the protective film include Alphan (registered trademark) EM-501, Alphan E-200, Alphan E-201F, Alphan FG-201, Alphan MA-411 (all manufactured by Oji F-Tex Co., Ltd.), Torayfan (registered trademark) KW37, Alphan 2578, Alphan 2548, Alphan 2500, Alphan YM17S, Therapeel (registered trademark) PJ271, Alphan PJ111, Alphan HP2, Alphan PJ101, Alphan WZ, Alphan MDA, Alphan MFA, Alphan TK07, Alphan BKE, Alphan BX8A, Alphan SY (all manufactured by Toray Industries, Inc.), GF-18, GF-818, GF-858 (all manufactured by Tamapoly Co., Ltd.), and the like.

[0110] [Photosensitive element roll] A further aspect of this embodiment is a photosensitive element roll formed by winding the above-mentioned photosensitive element. The photosensitive element roll may include a core for winding up the long photosensitive element, or may not include a core.

[0111] [Method of manufacturing photosensitive element] The photosensitive element according to the present embodiment as described above can be produced by the method described below. That is, another aspect of the present embodiment is a method for producing a photosensitive element. The manufacturing method includes: A method for producing a photosensitive element comprising a support film and a photosensitive resin layer, the method comprising the steps of: a step of preparing a preparation liquid of a photosensitive resin composition by mixing (A) an alkali-soluble polymer, (B) a compound having an ethylenically unsaturated bond, and (C) a biimidazole photopolymerization initiator with a solvent (preparation step); A step of applying the above-mentioned preparation onto a support film (application step); and A step of obtaining a photosensitive resin layer by heating the applied support film (a step of forming a photosensitive resin layer); Includes.

[0112] <Mixing process> In this step, the above-mentioned components (A), (B), and (C) are mixed with a solvent to prepare a prepared solution of a photosensitive resin composition.

[0113] Suitable solvents include ketones such as methyl ethyl ketone (MEK), and alcohols such as methanol, ethanol, isopropyl alcohol, etc. The solvent may be used alone or in combination of two or more kinds.

[0114] The content of the solvent is preferably in the range of 30 to 60 mass %, more preferably 33 to 55 mass %, and further preferably 35 to 57 mass %, based on the total amount of the photosensitive resin composition.

[0115] It is preferable to mix the solvent into the photosensitive resin composition so that the viscosity of the prepared solution of the photosensitive resin composition is 500 to 4000 mPa·sec at 25° C. The viscosity can be measured at 25° C. using a Brookfield viscometer (manufactured by Eikosha, model number DVNext).

[0116] <Coating process> In this step, the above-mentioned preparation is applied onto a support film. The preparation liquid can be applied to the support film by a method that has been conventionally used, such as a method of application using a roll coater, spin coater, bar coater, blade coater, curtain coater, screen printing machine, or the like, or a method of spray application using a spray coater.

[0117] <Photosensitive resin layer formation process> In this process, the support film coated with the above-mentioned preparation is heated to obtain a photosensitive resin layer. Specifically, in this process, the solvent in the preparation is distilled off by heating to form a photosensitive resin layer containing the photosensitive resin composition on the support film.

[0118] The heating temperature of the support film is preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 90°C or higher. By heating to 90°C or higher, the evaporation of the solvent contained in the preparation is accelerated, and the production efficiency of the photosensitive element is improved. In addition, the heating temperature of the support film is preferably 140°C or lower, more preferably 130°C or lower, and even more preferably 120°C or lower. By keeping the temperature at 140°C or lower, it is easy to prevent the progress of thermal polymerization of the photosensitive resin composition. The heating time of the support film is preferably 1 to 10 minutes.

[0119] <Protection process> The method for producing a photosensitive element includes, after the photosensitive resin layer forming step, A process of laminating a protective film on the photosensitive resin layer (protection process) may have

[0120] [Method of forming resist pattern] Another aspect of the present embodiment is a method for forming a resist pattern. The method comprises the steps of: laminating the photosensitive element to a substrate (lamination); a step of exposing the photosensitive resin layer of the laminated photosensitive element to light (exposure step); and a step of developing the exposed photosensitive resin layer; Includes.

[0121] <Lamination process> In this step, the photosensitive element is laminated on the substrate. Specifically, when the photosensitive element includes a protective film, the protective film is peeled off from the photosensitive element, and then the photosensitive resin layer is heat-pressed onto the substrate using a laminator. Examples of the material of the substrate include copper, stainless steel (SUS), glass, indium tin oxide (ITO), and the like. In addition, these substrates may be metal-coated insulating plates, such as copper-clad laminates, in which a conductor layer made of copper, stainless steel (SUS), or the like is formed on an insulating layer. Before heat-pressing the photosensitive resin layer onto the substrate, the surface of the substrate may be smoothed by washing with, for example, an aqueous solution of H2SO4 with a concentration of about 10% by mass, pure water, or the like.

[0122] The thermocompression bonding can be carried out, for example, by using a laminator equipped with rolls, or by passing a laminate of a substrate and a photosensitive resin layer between the rolls once or multiple times (hereinafter referred to as lamination). The heating temperature of the rolls during lamination is, for example, 40 to 160° C. Furthermore, the substrate may be preheated to 40 to 80° C. before lamination. The thermocompression bonding may be carried out in a reduced pressure environment.

[0123] <Exposure process> In this step, the photosensitive resin layer of the laminated photosensitive element is exposed to light. The exposure can be performed using an exposure machine, and can be performed after peeling off the support film as desired. When the exposure is performed through a photomask, the exposure amount is determined by the light source illuminance and the exposure time, which may be measured by an actinometer.

[0124] This step may be performed by direct imaging exposure. In direct imaging exposure, a photomask is not used, and exposure is performed directly by a direct imaging device. As a light source, a semiconductor laser having a wavelength of 350 to 410 nm or an ultra-high pressure mercury lamp is used. When the drawing pattern is controlled by a computer, the exposure amount is determined by the illuminance of the exposure light source and the moving speed of the substrate.

[0125] The light irradiation method used in the exposure step is preferably at least one method selected from the group consisting of a projection exposure method, a proximity exposure method, a contact exposure method, a direct imaging exposure method, and an electron beam direct writing method, and it is more preferable to use a projection exposure method or a direct imaging exposure method.

[0126] <Heating process (post-exposure heating process)> The method for forming a resist pattern includes the following steps between the exposure step and the development step: A step of heating the exposed photosensitive resin layer and the substrate (heating step) The heating temperature is preferably about 30 to about 200° C., more preferably 30 to 150° C., and even more preferably 35 to 120° C. By carrying out this step, it is easy to realize improvements in adhesion and resolution of the resist pattern. For heating, a heating furnace using hot air, infrared or far infrared rays can be used, and a thermostatic bath, a hot plate, a hot air dryer, an infrared dryer, a hot roll, etc. can also be used.

[0127] The time elapsed from the exposure step to the heating step, for example, the time elapsed from the time exposure is stopped to the time heating is started, is preferably 10 to 600 seconds, more preferably 20 to 300 seconds.The time elapsed from the time heating is started to the time heating is stopped is preferably 1 to 120 seconds, more preferably 5 to 60 seconds.

[0128] <Developing process> In this step, the photosensitive resin layer after exposure is developed. Specifically, the unexposed or exposed portion of the photosensitive resin layer after exposure is removed with a developer using a developing device. If there is a support film on the photosensitive resin layer after exposure, it is preferable to remove the support film before carrying out this step. Examples of the developer include a developer containing an alkaline aqueous solution. The unexposed or exposed portion is removed by this step, and a resist pattern can be obtained.

[0129] The alkaline aqueous solution is preferably an aqueous solution of Na2CO3, K2CO3, tetramethylammonium hydroxide, or the like. The alkaline aqueous solution is selected according to the characteristics of the photosensitive resin layer, and generally, an aqueous solution of Na2CO3 with a concentration of 0.2 to 2 mass % is used. The alkaline aqueous solution may contain a surfactant and an antifoaming agent, and may also contain a small amount of a solvent to promote development. The temperature of the developer in the development step is preferably kept constant within the range of 20 to 40°C.

[0130] <Water washing process> The method for forming a resist pattern includes the following steps: A process of washing the resist pattern and the substrate with water (washing process) According to this step, the developer remaining on the resist pattern and the substrate can be reduced. The washing water is selected from pure water, industrial water, and the like according to the characteristics of the photosensitive resin layer, and preferably contains a polyvalent metal salt such as MgSO4 at a concentration of 0.001 to 1 mass % from the viewpoint of excellent rectangularity and resolution of the resist pattern. The temperature of the washing water in the washing step is preferably kept constant within the range of 20 to 40°C.

[0131] <Heating process (heating process after development)> The method for forming a resist pattern includes the steps of: A process of further heating the resist pattern and the substrate at 60 to 300°C (heating process) By carrying out this step, the chemical resistance of the resist pattern can be improved. In the heating step, a heating furnace using hot air, infrared rays, or far infrared rays can be used.

[0132] [Manufacturing method of wiring board] One aspect of this embodiment is a method for manufacturing a wiring board. The method comprises the steps of: a step of forming a resist pattern on a substrate using the photosensitive element (resist pattern forming step); A step of forming a conductor pattern by etching or plating the substrate on which the resist pattern has been formed (a conductor pattern forming step); and A step of peeling the resist pattern from the substrate (peeling step); Includes.

[0133] Further, one aspect of this embodiment includes the following steps: a step of forming a resist pattern on a substrate made of a metal-coated insulating plate using the photosensitive element (resist pattern forming step); A step of forming a conductor pattern by plating the substrate on which the resist pattern has been formed (a conductor pattern forming step); A step of peeling the resist pattern from the substrate (peeling step); a step of removing the conductor layer other than the conductor pattern (a conductor layer removing step); The method for manufacturing a wiring board includes the steps of:

[0134] Of these, the resist pattern forming step is as described above in the section [Method of forming a resist pattern], and therefore a description thereof will be omitted here.

[0135] <Conductor pattern formation process> In this step, the substrate on which the resist pattern has been formed is etched or plated to form a conductor pattern. The conductor pattern can be formed, for example, by using a metal plate or a metal-coated insulating plate as the substrate and etching or plating the surface (e.g., copper surface) of the substrate exposed by development.

[0136] (Plating method) The method for forming the conductive pattern by plating is, for example, as follows. The substrate after the development step is immersed in an acidic degreasing bath such as a 1 to 50 mass % sulfuric acid aqueous solution for 1 to 60 minutes at 20 to 60° C. The immersed substrate is washed with water, and then immersed in a 1 to 50 mass % sulfuric acid aqueous solution at room temperature for 1 to 60 minutes.

[0137] Also, an aqueous solution containing 1 to 15 mass% copper sulfate, 0.1 to 30 mass% sulfuric acid, and 1 to 1000 ppm hydrochloric acid is prepared, Next, a brightener (in one embodiment, Cupracid HL and Cupracid GS manufactured by Atotech Corporation) is further mixed in an amount of 0.01 to 40 ml / l and 1 to 200 ml / l, respectively, to prepare a copper sulfate plating solution.

[0138] The prepared copper sulfate plating solution was used in a Haring Cell uniform plating device (manufactured by Yamamoto Plating Tester Co., Ltd.) at an applied current density of 0.1 to 10 A / dm 2 The plating is performed for 1 to 300 minutes. This allows the formation of a conductive pattern.

[0139] The thickness of the copper plating film can be appropriately changed according to the thickness of the resist pattern. For example, the thickness of the copper plating film is preferably in the range of 1 μm or more and the thickness (μm) of the resist pattern minus 2 μm or less. In this specification, the thickness of the resist pattern refers to the thickness of the photosensitive resin layer after curing.

[0140] <Peeling process> In this process, the resist pattern is peeled off from the substrate. By using an aqueous solution having a stronger alkalinity than the developer, the resist pattern can be easily peeled off from the substrate. By carrying out this process, a wiring board (e.g., a printed wiring board) having a desired wiring pattern can be obtained.

[0141] The alkaline aqueous solution for stripping (hereinafter also referred to as "stripping solution") may be an aqueous solution of NaOH or KOH with a concentration of 2 to 5% by mass, or an organic amine stripping solution. The stripping solution may contain a small amount of a water-soluble solvent. Examples of the water-soluble solvent include alcohol. The temperature of the stripping solution is preferably within a range of 40 to 70°C, and the immersion time in the stripping solution is preferably 1 to 30 minutes.

[0142] <Conductor layer removal process> When a conductive pattern is formed on a metal-coated insulating plate by plating, the conductive pattern is formed on the conductive layer of the metal-coated insulating plate. Therefore, from the viewpoint of insulating between the conductive patterns, it is preferable to remove the conductive layer other than the conductive pattern. Examples of the removal method include a method of peeling off the resist pattern and then performing etching.

[0143] Photosensitive elements are used in the manufacture of printed wiring boards; the manufacture of lead frames for mounting IC chips; precision processing of metal foils such as metal masks; the manufacture of packages such as ball grid arrays (BGA) and chip size packages (CSP); the manufacture of tape substrates such as chip-on-film (COF) and tape automated bonding (TAB); the manufacture of semiconductor bumps; and the manufacture of partitions for flat panel displays such as ITO electrodes, address electrodes, and electromagnetic shields. can be utilized for. Unless otherwise specified, the values ​​of the above parameters are measured in accordance with the measurement methods in the examples described below. EXAMPLES

[0144] The present embodiment will be further described below with reference to examples and comparative examples. However, the present embodiment is not limited to the following examples without departing from the gist of the present embodiment. In the examples and comparative examples, various physical properties were measured by the following methods.

[0145] [Synthesis of component (A)] The monomers (copolymerization components) shown in the table below were mixed with azobisisobutyronitrile in the amounts (unit: parts by mass) shown in the table below to prepare solution (a). 200 g of methyl ethyl ketone and 100 g of ethanol were placed in a flask equipped with a stirrer, reflux condenser, thermometer, dropping funnel, and nitrogen gas inlet tube, and the mixture was stirred while blowing nitrogen gas into the flask and heated to 80°C. 300 g of the above solution (a) was then added dropwise to the flask at a constant dropping rate over 4 hours, and the mixture was stirred at 80°C for 2 hours.

[0146] Next, 50 parts by mass of a mixed solution containing 30 parts by mass of methyl ethyl ketone and 20 parts by mass of ethanol were mixed with 0.5 parts by mass of azobisisobutyronitrile to prepare solution (b). 50 g of solution (b) was added dropwise to the flask containing solution (a) at a constant rate over 10 minutes, and then stirred at 80°C for another 3 hours. The solution in the flask was then heated to 90°C over 30 minutes, and then kept at 90°C for 2 hours. After that, stirring was stopped and the solution was cooled to room temperature (25°C). Thus, solutions of alkali-soluble polymers A1 to A5 were obtained. The weight average molecular weights (Mw) of alkali-soluble polymers A1 to A5 are shown in the table below.

[0147] The weight average molecular weight was measured by gel permeation chromatography (GPC) and calculated using a calibration curve of standard polystyrene. The GPC conditions are shown below. (GPC conditions) Pump: JASCO PU-4580 Degasser: DG-2080-53 Column oven: CO-1560 Columns: 4 in total Shodex KF-807 / KF-806M×2 / KF-802.5 Eluent: Tetrahydrofuran Measurement temperature: 40℃ Flow rate: 1.00mL / min Detector: JASCO RI-1530

[0148] [Preparation of evaluation samples] <Preparation of Photosensitive Element> The components shown in the table below and methyl ethyl ketone were mixed so that the amount of each component as solid content corresponded to the amount shown in the table below and the solid content concentration corresponded to 60 mass%. Then, the mixture was thoroughly stirred, thereby obtaining a preparation liquid of a photosensitive resin composition. The amount (parts by mass) is the mass of non-volatile content (solid content amount). A 16 μm thick polyethylene terephthalate film (manufactured by Toray Industries, Inc., QS71) was used as a support film, and the preparation liquid was uniformly applied to the surface of the film using a bar coater. Then, the film was dried in a dryer at 95° C. for 2 minutes and 30 seconds to form a photosensitive resin layer with a film thickness of 25 μm. This resulted in obtaining a photosensitive element.

[0149] Next, a 19 μm polyethylene film (GF-818, manufactured by Tamapoly Co., Ltd.) was attached as a protective film to the surface of the photosensitive resin layer on the side on which the polyethylene terephthalate film was not laminated. The laminate of the support film, the photosensitive resin layer, and the protective film obtained in this manner was treated as a photosensitive element in this embodiment.

[0150] <Surface> A copper-clad laminate having a total thickness of 0.4 mm was prepared by laminating rolled copper foil having a thickness of 18 μm. The surface of the copper-clad laminate was washed with a 10 mass % H2SO4 aqueous solution and then washed with pure water.

[0151] <Lamination> The copper-clad laminate that had been subjected to the above surface preparation was preheated to 50° C. Then, while peeling off the polyethylene film (protective film) of the photosensitive element, the photosensitive resin laminate was laminated onto the copper-clad laminate at a roll temperature of 105° C. using a hot roll laminator (AL-700, manufactured by Asahi Kasei Corporation). This resulted in the preparation of a substrate for evaluation. Here, the air pressure during lamination was set to 0.35 MPa, and the lamination speed was set to 1.5 m / min.

[0152] <Exposure> Two hours after lamination, the substrate was exposed to light at a wavelength of 365 nm through a photomask having a predetermined mask pattern for projection exposure using a projection exposure machine (UX-23101 manufactured by Ushio Inc.).

[0153] <Heating> One minute after exposure, the substrate was heated for 30 seconds in a constant temperature incubator with a constant airflow (DKM600, manufactured by Yamato Scientific Co., Ltd.) set at 60°C.

[0154] <Development> The polyethylene terephthalate film (support film) was peeled off from the photosensitive resin layer. After that, development (developing spray) was performed by spraying a 1% by mass Na2CO3 aqueous solution at 30°C for a predetermined time at a spray pressure of 0.15 MPa using an alkaline developing machine (manufactured by Fuji Kiko Co., Ltd., a dry film developing machine). In this example, after the developing spray, a water washing spray was further performed.

[0155] [Exposure and development conditions] <Developing conditions> A substrate that had been subjected to the above-mentioned <lamination> was prepared, and the above-mentioned <development> was carried out without carrying out either the above-mentioned <exposure> or the above-mentioned <heating>. In this way, the "shortest development time", which is the shortest time required for the photosensitive resin layer in the unexposed area to completely dissolve, was measured. In this embodiment, the time for the developing spray and the time for the washing spray after development were each set to twice the shortest developing time.

[0156] <Exposure conditions> A substrate that had been subjected to the lamination process was prepared, and exposed to light using a photomask having a mask pattern (see FIG. 2) with a line width (L) / space width (S) (hereinafter simply abbreviated as "L / S") of 8 / 8 (unit: μm). After that, <heating> and <development> were performed, thereby forming a resist pattern on the substrate. The formed resist pattern was observed at a magnification of 100 times using an optical microscope, thereby obtaining an observation image of the line width of the pattern. The exposure dose (unit: mJ / cm) that resulted in a line width of 8 μm was 2 ) was adopted as the optimum exposure amount, and the exposure amounts in the following evaluations were all carried out at the optimum exposure amount.

[0157] FIG. 2 is a plan view showing an example of the configuration of a mask pattern. In the figure, in an area 100 on the photomask, an area that transmits the exposure light is indicated by the reference numeral 10 (transmitting area 10), and an area that does not transmit the exposure light (shaded area) is indicated by the reference numeral 1 (light-shielding area 1). The light-shielding area 1 has a predetermined width and extends in the X direction, and a plurality of such light-shielding areas 1 are arranged in the width direction (Y direction) at predetermined intervals. In this embodiment, since the unexposed portion of the photosensitive resin layer is removed through the <development> process, it is expected that a resist pattern having an L / S corresponding to the width of the light-shielding area 1 (S: space) and the width of the transmitting area 10 (L: line) will be formed by exposing the photosensitive resin layer through a photomask having the mask pattern of FIG. 2, followed by heating and development.

[0158] <Adhesion> Evaluation was carried out using a photomask having a mask pattern (see FIG. 3) with L / S of x / 3x {x=1 to 15 (varying at 0.5 μm intervals)} (unit: μm). That is, the substrate that had been subjected to the above-mentioned <surface preparation> and <lamination> was exposed through the photomask at an optimal exposure dose. Then, the above-mentioned <heating> and <development> were carried out to form a resist pattern. The formed resist pattern was observed at a magnification of 100 times using an optical microscope, thereby obtaining an observation image of the line width of the pattern.

[0159] FIG. 3 is a plan view showing an example of the configuration of a mask pattern. In the figure, in the region 100A on the photomask, the region that transmits the exposure light is indicated by the reference numeral 10 (transmitting region), and the region that does not transmit the exposure light (shaded region) is indicated by the reference numeral 1 (light-shielding region). The transmitting region 10 has a predetermined width and extends in the x direction, and a plurality of such transmitting regions 10 are arranged in the width direction (y direction) at predetermined intervals. In this embodiment, since the unexposed portion of the photosensitive resin layer is removed through the <development> process, it is expected that a resist pattern having an L / S corresponding to the width of the transmitting region 10 (L: line) and the width of the light-shielding region 1 (S: space) is formed by exposing the photosensitive resin layer through a photomask having the mask pattern of FIG. 3, and then heating and developing it.

[0160] In the observed image, the minimum line width that can be formed without the line portion (exposed portion) becoming meandering or chipping was taken as the value of "adhesion line width (unit: μm)". The smaller this value, the better the adhesion. Adhesion was evaluated according to the following criteria. Adhesion evaluation results of B (good) or higher were considered to be acceptable. (Evaluation Criteria) A (very good): The adhesion line width is 3.5 μm or less. B (Good): The contact line width is greater than 3.5 μm and less than 4.0 μm. C (standard): Contact line width is greater than 4.0 μm and less than 5.0 μm. D (poor): The value of the adhesion line width is greater than 5.0 μm.

[0161] <Resolution> The evaluation was performed using a photomask having a mask pattern (see, for example, FIG. 2) in which L / S is x / x{x=1 to 15 (varying at 0.5 μm intervals)} (unit: μm). That is, the substrate that had been subjected to the above-mentioned <surface preparation> and <lamination> was exposed through the photomask at an optimal exposure dose. Then, the above-mentioned <heating> and <development> were performed to form a resist pattern. The formed resist pattern was observed at a magnification of 100 times using an optical microscope, thereby obtaining an observation image of the line width of the pattern. In the observation image, the minimum space width at which the line portion (exposed portion) does not meander or chip, and the space portion (unexposed portion) is removed without residue was treated as the value of "resolution space width (unit: μm)". The smaller this value, the better the resolution.

[0162] <Independent fine line formation> Evaluation was carried out using a photomask having a mask pattern (see, for example, FIG. 4) with L / S of x / 200 {x=1 to 15 (varying at 0.5 μm intervals)} (unit: μm). That is, the substrate that had been subjected to the above-mentioned <surface preparation> and <lamination> was exposed to light at an optimal exposure amount through the photomask. Then, the above-mentioned <heating> and <development> were carried out to form a resist pattern. The formed resist pattern was observed at a magnification of 100 times using an optical microscope, thereby obtaining an observation image of the line width of the pattern. Depending on the mask pattern, when the interval between adjacent resist thin lines in the resist pattern is large, the resist thin lines may be observed to be formed independently. In this specification, such resist thin lines are referred to as "independent resist thin lines".

[0163] FIG. 4 is a plan view showing an example of the configuration of a mask pattern. In the figure, the mask pattern in region 100B on the photomask has a wider width (S: space) of the region 1 that does not transmit the exposure light than the mask pattern in the writing region 100A shown in Fig. 3. As in the case of Fig. 3, based on the mask pattern in this figure, it is theoretically expected that a resist pattern having the width (L: line) of the exposure region 10 and a corresponding L / S will be formed.

[0164] In the observed image, the minimum line width at which the resist independent thin lines were formed without any chipping was taken as the value of "independent thin line width (unit: μm)". Based on the magnitude of the difference between the value of "independent thin line width" and the value of "adhesive line width", the "independent thin line formability" was evaluated according to the following criteria. The smaller this difference, the better the independent thin line formability. (Evaluation Criteria) A (very good): (Independent thin line width) - (Adhesive line width) is 1.0 μm or less. B (Good): (Independent thin line width) - (Adhesive line width) value is greater than 1.0 μm and less than 2.0 μm. C (standard): (Independent thin line width) - (Adhesive line width) is greater than 2.0 μm.

[0165] <Formation of plated copper wiring> The substrate after the above <development> was washed for 5 minutes with an acid cleaner Cupura Pro S2 (ATOTEC) at 35°C, washed with ion-exchanged water at 35°C, washed with ion-exchanged water at 25°C, and washed with 10% sulfuric acid at 25°C. In this way, the substrate was subjected to a pretreatment for electrolytic copper plating. In this way, a substrate for evaluation of plating resistance after plating pretreatment was obtained.

[0166] Next, a copper sulfate aqueous solution with a concentration of 121 g / l was prepared and diluted with sulfuric acid with a concentration of 19 mass % until the volume was 3.6 times. Then, concentrated hydrochloric acid was mixed in an amount to give a concentration of 200 ppm. Next, 0.4 ml / l and 20 ml / l of Cupracid HL and Cupracid GS were mixed as brighteners, respectively, to prepare a copper sulfate plating solution. Then, the above-mentioned plating resistance evaluation board (6 cm x 12.5 cm) was plated with the copper sulfate plating solution using a Haring cell uniform plating device (manufactured by Yamamoto Plating Tester Co., Ltd.) at a voltage of 0.05 V and a current density of 1.0 A / dm. 2 The copper plating was performed for 45 minutes. This resulted in a plated substrate. The thickness of the copper plating film at this time was 20 μm.

[0167] After plating, the substrate was immersed in an amine stripping solution (a 1:1 mixture of R-100S (15 vol%) manufactured by MGC and R-101 (8 vol%) manufactured by MGC) at 50°C for 3 minutes. After removing the substrate, it was washed with ion-exchanged water, and the resist pattern on the substrate was stripped off. The substrate was then air-dried to obtain a substrate for evaluation. The substrate was observed at a magnification of 100 times using an optical microscope, and an observation image was obtained.

[0168] In the observed image, the minimum line width at which the plated copper wiring was maintained in the space portion (unexposed portion) without peeling, breaking, or collapsing was adopted as the value of "resolved line width after plating (unit: μm)". Based on the magnitude of the difference between the value of "resolved line width after plating" and the value of "resolved space width", the formability of the plated copper wiring was evaluated according to the following criteria. The smaller this difference, the better the formability of the plated copper wiring. (Evaluation Criteria) A (Good): (Resolved line width after plating) - (Resolved space width) value is 0 μm. B (Standard): (Resolved line width after plating) - (Resolved space width) is greater than 0 μm and less than 1.0 μm. C (Poor): (Resolved line width after plating) - (Resolved space width) is greater than 1.0 μm.

[0169] Fig. 5 shows an example of an observation image that can be obtained in the above-mentioned <Plated copper wiring formability>. Fig. 5(a) shows an example of "collapse" of a plated copper wiring, and Fig. 5(b) shows an example of "peeling and breakage" of a plated copper wiring. In each figure, a plated copper wiring 30 is formed on a substrate 20. 5(a), a portion of the plated copper traces 30A, which should be formed by standing vertically, is tilted inward. In this case, in the observed image, the "tilt" is observed as the plated copper traces 30A that have lost their straightness. 5(b), some of the plated copper wiring 30 has peeled off and broken off from the substrate 20. In this case, in the vertical observation image, the "peeling and breaking" is observed as a blank area (dotted line area S1 in the figure) where the plated copper wiring is not formed in a place where the plated copper wiring should essentially be formed. With regard to "peeling and breakage," "peeling" refers to the phenomenon in which the entire continuous plated copper wiring is lost from the substrate, and "breakage" refers to the phenomenon in which only a portion of the continuous plated copper wiring is lost from the substrate.

[0170] <Independent thin wire remaining after plating> The substrates prepared in the evaluation of the above-mentioned <Independent thin line formability> were used to obtain substrates for evaluation in the same manner as in the evaluation of the above-mentioned <Plated copper wiring formability>. The substrates were observed at a magnification of 100 times using an optical microscope, and an observation image was obtained.

[0171] In the observed image, the minimum line width where no plating erosion (short circuit) occurred in the area where the resist pattern was peeled off was determined, and this was adopted as the "independent thin-line plating space width (unit: μm)." Based on the magnitude of the difference between the "independent thin-line plating space width" value and the "independent thin-line line width" value, the independent thin-line survival after plating was evaluated according to the following criteria. The smaller this difference, the better the independent thin-line survival after plating. (Evaluation Criteria) A (Good): (Independent fine wire plating space width) - (Independent fine wire line width) is 1.0 μm or less. B (standard): (Independent fine-wire plating space width) - (Independent fine-wire line width) exceeds 1.0 μm.

[0172] 6 is an example of an observation image that can be obtained in the above <Independent thin line remaining after plating>. In the figure, plated copper wiring 30 is formed on substrate 20. On the other hand, since the plating is provided in the area where the resist pattern has been removed by development, it is preferable that the plating does not corrode the resist pattern area. In Fig. 6, part of the plated copper wiring 30 is corroded up to the area where the resist pattern was formed (dotted area S2 in the figure). The smaller the degree of this corrosion, the better the result of <Independent thin wire survival after plating> can be obtained.

[0173] <Transmittance of photosensitive resin layer> The protective film of the photosensitive element was peeled off. Then, the transmittance (%) of the photosensitive resin layer at a wavelength of 365 nm was measured using a spectrophotometer U-3010 (manufactured by Hitachi High-Technologies Corporation) with a polyethylene terephthalate film (support film) as a reference. The measurement was performed with a slit set at 4 nm and a scan speed of 600 nm / min.

[0174] [Table 1]

[0175] [Table 2]

[0176] [Table 3]

[0177] [Table 4]

[0178] [Table 5]

[0179] [Table 6]

[0180] [Table 7]

[0181] As can be seen from the above table, in the Examples, the evaluation results for both <adhesion> and <formability of plated copper wiring> were A or B. That is, in the Examples, <adhesion> and <formability of plated copper wiring> were compatible, and in a particularly preferred embodiment, both <formability of independent thin wires> and <remainability of independent thin wires after plating> were good. [Industrial Applicability]

[0182] By using the photosensitive element according to the present invention, a resist pattern having good adhesion and good copper plating wiring formability can be obtained. Such a photosensitive element can be widely used as a photosensitive element for forming a resist pattern on a printed wiring board or the like. [Explanation of symbols]

[0183] 1: Area that does not transmit exposure light (light-shielding area) 10: Area that transmits exposure light (transmitting area) 20: Substrate 30: Plated copper wiring 30A: Plated copper wiring 100: Area on the photomask 100A: Area on the photomask 100B: Area on photomask 101: Photosensitive resin layer 110: Foreign matter 111: Precipitate 112: Air bubbles L: Line S: Space S1: area S2: area

Claims

1. A photosensitive element comprising a support film and a photosensitive resin layer containing a photosensitive resin composition, The photosensitive resin composition contains the following components based on the total solid content by mass in the photosensitive resin composition: (A) Alkali-soluble polymer: 30 to 70 mass %; (B) a compound having an ethylenically unsaturated bond: 20 to 60% by mass; and (C) Biimidazole photopolymerization initiator: 4.0 to 10.0 mass%; Including, The content of the structural unit derived from benzyl (meth)acrylate in the component (A) is 40 mass% or more based on the entire component (A), The content of the compound having two ethylenically unsaturated bonds in one molecule in the component (B) is 80 mass% or more based on the entire component (B). Photosensitive element.

2. The photosensitive element according to claim 1 , wherein the content of the component (C) is 4.50% by mass or more based on the total solid content by mass of the photosensitive resin composition.

3. 2. The photosensitive element according to claim 1, wherein the content of the component (C) is 4.75% by mass or more based on the total solid content by mass of the photosensitive resin composition.

4. 2. The photosensitive element according to claim 1, wherein the content of the component (C) is 5.25% by mass or more based on the total solid content by mass of the photosensitive resin composition.

5. 2. The photosensitive element according to claim 1, wherein the content of the component (C) is 6.00% by mass or more based on the total solid content by mass of the photosensitive resin composition.

6. 2. The photosensitive element according to claim 1, wherein the content of the structural unit derived from benzyl (meth)acrylate in the component (A) is 50% by weight or more based on the entirety of the component (A).

7. 2. The photosensitive element according to claim 1, wherein the content of the structural unit derived from benzyl (meth)acrylate in the component (A) is 60% by weight or more based on the entirety of the component (A).

8. 2. The photosensitive element according to claim 1, wherein the content of the compound having two ethylenically unsaturated bonds in one molecule is 90% by mass or more based on the entirety of the component (B).

9. The compound having two ethylenically unsaturated bonds in one molecule is represented by the following general formula (II): 【Chemistry 1】 (In the formula, R ２ are each independently a hydrogen atom or a methyl group; X ２ O and Y ２ Each O is independently an oxyethylene group or an oxypropylene group, m3, m4, n2, and n3 are independently an integer of 0 to 40, m3+m4 is 1 to 40, and n2+n3 is 0 to 20. The photosensitive element of any one of claims 1 to 8, comprising a compound represented by the formula:

10. The photosensitive element according to claim 9 , wherein the content of the compound represented by formula (II) is 90% by mass or more based on the entirety of the component (B).

11. The compound having two ethylenically unsaturated bonds in one molecule is A compound in which the average value of n2+n3+m3+m4 in the general formula (II) is 10 or less; and a compound in which in general formula (II) an average value of n2+n3+m3+m4 is 15 or more.

12. The photosensitive resin composition contains the component (C) in an amount of 5.0% by mass or more based on the total solid content mass of the photosensitive resin composition, the photosensitive resin layer has an absorbance (Y) of 0.35 or less at a wavelength of 365 nm when the layer has a thickness of 25 μm; the contribution (X) of the absorbance of the (C) component to the absorbance (Y) is 40% or more; The contribution (X) is expressed by the following formula (1): X(%)=100×εc / absorbance of photosensitive resin layer (Y) (1) ε: absorbance change per 1 mass% of component (C) c: Content (mass%) of component (C) relative to the total solid component mass of the photosensitive resin composition The photosensitive element of any one of claims 1 to 8, wherein the surface area is calculated by:

13. The photosensitive element of claim 12 , wherein the contribution (X) is 55% or greater.

14. The photosensitive element of claim 12 , wherein the contribution (X) is 65% or greater.

15. The photosensitive element of claim 12 , wherein the contribution (X) is 85% or greater.

16. The photosensitive element of claim 12 , wherein the absorbance (Y) is less than or equal to 0.

30.

17. The photosensitive element of claim 12 , wherein the absorbance (Y) is less than or equal to 0.

25.

18. The photosensitive resin composition comprises (D) Other photopolymerization initiators Further comprising: The photosensitive element according to any one of claims 1 to 8, wherein the component (D) includes at least one selected from the group consisting of a benzophenone compound, a pyrazoline compound, an anthracene compound, and a coumarin compound.

19. The photosensitive resin composition further contains (D) another photopolymerization initiator, 20. The photosensitive element of claim 18, wherein the component (D) includes at least one selected from the group consisting of a benzophenone compound and a pyrazoline compound.

20. The photosensitive resin composition comprises (E) Polymerization inhibitor The photosensitive element of any one of claims 1 to 8, further comprising:

21. 21. The photosensitive element of claim 20, further comprising phenothiazine and / or tert-butylcatechol as the (E) polymerization inhibitor.

22. 21. The photosensitive element according to claim 20, wherein the content of the polymerization inhibitor (E) is 50 to 500 ppm based on the total solid content by mass of the photosensitive resin composition.

23. The photosensitive element of any one of claims 1 to 8, wherein the support film has an absorbance at 365 nm of 0.1 or less.

24. The photosensitive element of any one of claims 1 to 8, further comprising a protective film.

25. A method for forming a resist pattern using the photosensitive element according to any one of claims 1 to 8, comprising the steps of: The following steps: laminating the photosensitive element to a substrate; exposing the photosensitive resin layer of the laminated photosensitive element to light; and a step of developing the photosensitive resin layer after exposure; A method for forming a resist pattern comprising the steps of:

26. A photosensitive element roll formed by winding the photosensitive element according to any one of claims 1 to 8.

27. forming a resist pattern on a substrate using the photosensitive element according to any one of claims 1 to 8; forming a conductor pattern by etching or plating the substrate on which the resist pattern has been formed; peeling the resist pattern from the substrate; A method for manufacturing a wiring board comprising:

28. forming a resist pattern on a substrate made of a metal-coated insulating plate using the photosensitive element according to any one of claims 1 to 8; forming a conductor pattern by plating the substrate on which the resist pattern is formed; peeling the resist pattern from the substrate; removing the conductor layer other than the conductor pattern; A method for manufacturing a wiring board comprising the steps of:

29. The method for producing a wiring board according to claim 28, wherein a wiring board having a conductor pattern with a width of 10 μm or less is formed.

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