JP6569199B2 - Photosensitive resin composition, photosensitive element, resist pattern forming method and printed wiring board manufacturing method - Google Patents

Description

  The present invention relates to a photosensitive resin composition, a photosensitive element, a resist pattern forming method, and a printed wiring board manufacturing method.

  In the field of manufacturing printed wiring boards, a photosensitive resin composition is widely used as a resist material used for etching treatment or plating treatment. A photosensitive resin composition includes a support and a layer (hereinafter, also referred to as “photosensitive resin composition layer”) formed using the photosensitive resin composition on the support. Often used as a body).

  A printed wiring board is manufactured as follows, for example. First, a photosensitive element having a support and a photosensitive resin composition layer is prepared, and a photosensitive resin composition layer of the photosensitive element is formed on a circuit forming substrate (photosensitive layer forming step). Next, after peeling off and removing the support, the exposed portion is cured by irradiating a predetermined portion of the photosensitive resin composition layer with actinic rays (exposure step). Thereafter, by removing (developing) the unexposed portions from the substrate, a resist pattern that is a cured product of the photosensitive resin composition (hereinafter also referred to as “cured resist”) is formed on the substrate (developing step). ). The resulting resist pattern is etched or plated to form a circuit on the substrate (circuit formation process), and finally the resist pattern is peeled and removed to produce a printed wiring board (peeling process). .

  As an exposure method, conventionally, a method of exposing via a photomask using a mercury lamp as a light source has been used. In recent years, a direct drawing exposure method called DLP (Digital Light Processing) or LDI (Laser Direct Imaging), which directly draws on a photosensitive resin composition layer without using a photomask based on digital data of a pattern, has been proposed. ing. This direct drawing exposure method has better alignment accuracy than an exposure method through a photomask, and a high-definition pattern can be obtained, so that it is being introduced for manufacturing a high-density package substrate.

  In general, in the exposure process, it is desired to shorten the exposure time in order to improve production efficiency. However, in the above-described direct drawing exposure method, in addition to using monochromatic light such as a laser as a light source and irradiating a light beam while scanning the substrate, a long exposure time is required as compared with an exposure method using a conventional photomask. Tend. Therefore, in order to shorten the exposure time and increase the production efficiency, it is necessary to improve the sensitivity of the photosensitive resin composition than before.

  On the other hand, with the recent increase in the density of printed wiring boards, there is an increasing demand for a photosensitive resin composition capable of forming a resist pattern with excellent resolution (resolution). In particular, a photosensitive resin composition capable of forming a resist pattern having an L / S (line width / space width) of less than 10/10 (unit: μm) is required in the production of a package substrate.

  Conventionally, various photosensitive resin compositions have been studied in response to these requirements. For example, in the following Patent Documents 1 to 7, a photosensitive resin composition in which the above-described required properties are improved by using a specific binder polymer, photopolymerizable compound, photopolymerization initiator, and sensitizing dye. Things are disclosed.

JP-A-2005-301101 JP 2007-114452 A JP 2007-1222028 A International Publication No. 08/078483 International Publication No. 10/098175 International Publication No. 10/098183 International Publication No. 12/067107

  However, the conventional photosensitive resin composition still has room for improvement in terms of improving the resolution of the formed resist pattern.

  An object of this invention is to provide the photosensitive resin composition which can form the resist pattern excellent in the resolution, the photosensitive element using the same, the formation method of a resist pattern, and the manufacturing method of a printed wiring board.

  As a result of intensive studies to solve the above problems, the present inventors have obtained a specific binder polymer having a structural unit derived from (meth) acrylic acid, a photopolymerizable compound, and a photopolymerization initiator. It has been found that a photosensitive resin composition capable of forming a resist pattern with excellent resolution can be obtained by combining them, and the present invention has been completed.

  That is, the first aspect of the present invention includes a binder polymer having a structural unit derived from (meth) acrylic acid, a photopolymerizable compound, and a photopolymerization initiator, and the weight average molecular weight of the binder polymer. Is a photosensitive resin composition in which the binder polymer is a polymer obtained by reversible addition-fragmentation chain transfer polymerization (hereinafter also referred to as “RAFT polymerization”).

  The second aspect of the present invention comprises a binder polymer having a structural unit derived from (meth) acrylic acid, a photopolymerizable compound, and a photopolymerization initiator, and the weight average molecular weight of the binder polymer is 20000. It is the above, It is the photosensitive resin composition whose dispersity (weight average molecular weight / number average molecular weight) of the said binder polymer is 1.4 or less.

  When the photosensitive resin composition takes the above-described aspect, a resist pattern having excellent resolution can be formed. According to the photosensitive resin composition, it is possible to form a resist pattern having an L / S (line width / space width) of less than 10/10 (unit: μm).

  According to a third aspect of the present invention, there is provided a support and a photosensitive resin composition layer formed on the support and formed from the photosensitive resin composition of the first aspect or the second aspect. A photosensitive element provided. By using such a photosensitive element, it is possible to efficiently form a resist pattern particularly excellent in resolution.

  According to a fourth aspect of the present invention, there is provided a photosensitive layer forming step of forming a photosensitive resin composition layer on a substrate using the photosensitive resin composition of the first aspect or the second aspect, and the photosensitive resin. An exposure step of irradiating at least a part of the composition layer with actinic rays and photocuring the region to form a cured product region; and regions other than the cured product region of the photosensitive resin composition layer And a developing step of forming a resist pattern, which is the cured product region, on the substrate by removing from the substrate. According to this resist pattern forming method, a resist pattern having excellent resolution can be efficiently formed.

  In the resist pattern formation method, the wavelength of the active light to be irradiated is preferably in the range of 340 nm to 430 nm. Thereby, a resist pattern with a better resolution can be formed more efficiently with excellent sensitivity.

  According to a fifth aspect of the present invention, there is provided a printed wiring board manufacturing method including a step of etching or plating a substrate on which a resist pattern is formed by the resist pattern forming method. According to this manufacturing method, a printed wiring board having high-density wiring such as a high-density package substrate can be efficiently manufactured with excellent accuracy and high productivity.

  ADVANTAGE OF THE INVENTION According to this invention, the photosensitive resin composition which can form the resist pattern excellent in resolution, the photosensitive element using the same, the formation method of a resist pattern, and the manufacturing method of a printed wiring board can be provided.

It is a schematic cross section which shows one Embodiment of the photosensitive element of this invention. It is a perspective view which shows typically an example of the manufacturing process of the printed wiring board by a semi-additive construction method.

  Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

In the present specification, “(meth) acrylic acid” means at least one of acrylic acid and methacrylic acid, and “(meth) acrylate” means at least one of acrylate and methacrylate. The “(poly) oxyethylene group” means at least one of an oxyethylene group and a polyoxyethylene group in which two or more ethylene groups are connected by an ether bond. The “oxyethylene group” is a group represented by (—CH ₂ CH ₂ —O—) and is also referred to as ethylene oxide. The “(poly) oxypropylene group” means at least one of an oxypropylene group and a polyoxypropylene group in which two or more propylene groups are connected by an ether bond. The “oxypropylene group” is a group represented by (—CHCH ₃ CH ₂ —O—), a group represented by (—CH ₂ CHCH ₃ —O—) or (—CH ₂ CH ₂ CH ₂ -O-), also referred to as propylene oxide. “EO-modified” means a compound having a (poly) oxyethylene group, “PO-modified” means a compound having a (poly) oxypropylene group, and “EO” “PO-modified” means a compound having both a (poly) oxyethylene group and a (poly) oxypropylene group.

  In this specification, the term “process” is not limited to an independent process, and is included in this term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. It is. Moreover, the numerical value range shown using "to" shows the range which includes the numerical value described before and behind "to" as a minimum value and a maximum value, respectively. Furthermore, the content of each component in the composition means the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition. . Further, the term “layer” includes a structure formed in a part in addition to a structure formed over the entire surface when observed as a plan view. Further, the term “lamination” indicates that the layers are stacked, and two or more layers may be bonded, or two or more layers may be detachable.

<Photosensitive resin composition>
The photosensitive resin composition of the present embodiment contains (A) component: binder polymer, (B) component: photopolymerizable compound, and (C) component: photopolymerization initiator. The photosensitive resin composition of this embodiment contains the specific binder polymer (henceforth a "specific binder polymer") which has a structural unit derived from (meth) acrylic acid as (A) component. The weight average molecular weight of the specific binder polymer is 20000 or more. In the first embodiment, the specific binder polymer is a polymer obtained by reversible addition-fragmentation chain transfer polymerization. In the second embodiment, the specific binder polymer has a dispersity (weight average molecular weight / number average molecular weight) of 1. 4 or less. The photosensitive resin composition of this embodiment may further contain other components as needed. For example, the photosensitive resin composition of the present embodiment preferably contains (D) a sensitizing dye and / or (E) a hydrogen donor in addition to the components (A) to (C) described above.

  By using a specific binder polymer having a structural unit derived from (meth) acrylic acid, a photopolymerizable compound, and a photopolymerization initiator, a photosensitive resin composition capable of forming a resist pattern with excellent resolution is formed. be able to. Although the detailed reason for the above effect is not necessarily clear, it can be considered as follows. Compared with the binder polymer obtained by free radical polymerization used in the conventional photosensitive resin composition, the binder polymer having a weight average molecular weight of 20000 or more and obtained by reversible addition-fragmentation chain transfer polymerization is a binder polymer. It is presumed that the arrangement of the components inside is different. By using such a binder polymer, the permeability of the developer, the exudation of low molecular components during development, and the like are suppressed, so it is assumed that the resolution is improved compared to conventional photosensitive resin compositions. Is done. In addition, since the use of a binder polymer having a weight average molecular weight of 20000 or more and a dispersity of 1.4 or less suppresses leakage of low molecular components during development, the conventional photosensitive resin composition It is estimated that the resolution is improved compared to

(A) component: Binder polymer The photosensitive resin composition contains the specific binder polymer which has a structural unit derived from (meth) acrylic acid at least as (A) component. The first aspect of the specific binder polymer is a binder polymer having a weight average molecular weight of 20000 or more obtained by reversible addition-fragmentation chain transfer polymerization. A second embodiment of the specific binder polymer is a binder polymer having a weight average molecular weight of 20000 or more and a dispersity of 1.4 or less. The component (A) may further contain a binder polymer other than the specific binder polymer as necessary. (Meth) acrylic acid is preferably a compound represented by the following general formula (1).

In the general formula (1), R ¹ represents a hydrogen atom or a methyl group, and R ¹ is preferably a methyl group.

  The specific binder polymer may have other structural units other than the above structural units. Examples of the other structural units include structural units derived from the following other polymerizable monomers.

  Other polymerizable monomers are not particularly limited as long as they are polymerizable with (meth) acrylic acid and are different from (meth) acrylic acid. Other polymerizable monomers include (meth) acrylic acid alkyl ester, (meth) acrylic acid cycloalkyl ester, (meth) acrylic acid hydroxyalkyl ester, (meth) acrylic acid benzyl, (meth) acrylic acid furfuryl, Tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, Glycidyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, (meta ) Dicyclopentanyl acrylate Cyethyl, isobornyloxyethyl (meth) acrylate, cyclohexyloxyethyl (meth) acrylate, adamantyloxyethyl (meth) acrylate, dicyclopentenyloxypropyloxyethyl (meth) acrylate, dimethacrylate (meth) acrylate (Meth) acrylic acid esters such as cyclopentanyloxypropyloxyethyl, dicyclopentenyloxypropyloxyethyl (meth) acrylate, and adamantyloxypropyloxyethyl (meth) acrylate; styrene or α-methylstyrene; diacetone acrylamide Such as acrylamide; acrylonitrile and the like. These can be used alone or in any combination of two or more.

  The specific binder polymer preferably further has a structural unit derived from styrene or α-methylstyrene, in addition to the structural unit derived from (meth) acrylic acid, from the viewpoint of improving adhesion and peeling properties.

  In the case where the specific binder polymer has a structural unit derived from styrene or α-methylstyrene, the content is more excellent in adhesion and release properties, and from the viewpoint of further excellent adhesiveness and peeling properties, all of the polymerizable monomers constituting the specific binder polymer The mass is preferably 10% by mass to 70% by mass, more preferably 15% by mass to 60% by mass, and still more preferably 20% by mass to 55% by mass. From the viewpoint of excellent adhesion, the content is preferably 10% by mass or more, more preferably 15% by mass or more, and further preferably 20% by mass or more. Moreover, from the point which is further excellent in peeling characteristics, this content is preferably 70% by mass or less, more preferably 60% by mass or less, and further preferably 55% by mass or less.

  The specific binder polymer may further have a structural unit derived from (meth) acrylic acid alkyl ester in addition to the structural unit derived from (meth) acrylic acid, from the viewpoint of further improving developability and peeling properties. preferable.

  The (meth) acrylic acid alkyl ester is preferably a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 12 carbon atoms, more preferably a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 8 carbon atoms. preferable. Examples of the (meth) acrylic acid alkyl ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, (meth) Hexyl acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate and (meth) ) Dodecyl acrylate. These can be used alone or in any combination of two or more.

  When the specific binder polymer has a structural unit derived from (meth) acrylic acid alkyl ester, the content of the polymerizable monomer constituting the specific binder polymer in that the content is further excellent in peeling properties, resolution, and adhesion. Is preferably 1% by mass to 30% by mass, more preferably 1% by mass to 20% by mass, and even more preferably 2% by mass to 10% by mass, based on the total mass (100% by mass). preferable. This content is preferably 1% by mass or more and more preferably 2% by mass or more from the viewpoint of further exfoliation properties. Further, in terms of further excellent resolution and adhesion, the content is preferably 30% by mass or less, more preferably 20% by mass or less, and further preferably 10% by mass or less.

  The specific binder polymer is, for example, (meth) acrylic acid, styrene or α-methylstyrene, (meth) acrylic acid alkyl ester, and other polymerizable used as necessary, as a polymerizable monomer (monomer). The monomer can be obtained by reversible addition-fragmentation chain transfer polymerization by a conventional method.

  In this reversible addition-cleavage chain transfer polymerization, a thiocarbonate compound having a structure represented by the general formula (2) can be used as a chain transfer agent.

（Ｒは、一価の基を示し、Ｚは、一価の基を示す。）

(R represents a monovalent group, and Z represents a monovalent group.)

  Here, as R, cumyl group, cyanopropyl group, phenylpropyl group, cyanophenylmethyl group, ethylcarboxypropyl group, 2,4,4-trimethylpentan-2-yl group, 1-cyanoethyl group, 1-phenyl Preferred examples include an ethyl group, a tertiary butyl group, a cyanomethyl group, and a benzyl group.

  Z is preferably a phenyl group, a methylthioyl group, a pyrrole group, a methyl group, a phenoxy group, an ethoxy group, a dimethylamino group, or the like.

  Specific examples of these chain transfer agents include cumyl dithiobenzoate, 2-cyano-2-propylbenzothioate, 4-cyano-4 [(dodecylsulfanylthiocarbonyl) sulfanyl] pentanoic acid, cyanomethylmethyl (phenyl) Carbamodithioate, 4-cyano-4- (phenylcarbonothioylthio) pentanoic acid, 2-cyano-2-propyldodecyltrithiocarbonate, 2- (dodecylthiocarbonothioylthio) -2-methylpropionic acid, Although cyanomethyl dodecyl trithio carbonate etc. are mentioned and these are marketed, it is not limited to these.

  By controlling the molar ratio of the polymerizable monomer and the molar ratio of the thiocarbonate compound having the structure represented by the general formula (2), the molecular weight of the obtained binder polymer is adjusted to be in a preferred range. Is possible.

  In order to obtain a specific binder polymer, a radical initiator may be used. Examples of the radical initiator include azobisisobutyronitrile.

  In general, the molar ratio of the chain transfer agent (for example, the thiocarbonate compound having a structure represented by the general formula (2)) to the radical initiator is preferably 20/1 to 1/5, and 10/1. More preferably, it is ˜¼. Since the molar ratio of the thiocarbonate compound having the structure represented by the general formula (2) and the radical initiator is 20/1 or less, the polymerization reaction rate can be increased while maintaining monodispersity, so that it can be industrially used. On the other hand, when the ratio is 1/5 or more, chain transfer from the radical initiator directly to the monomer can be avoided.

  The temperature of the polymerization reaction varies depending on the decomposition temperature of the radical initiator used, and is not particularly limited. Generally, the half-life decomposition temperature is minus 2 ° C. to plus 20 ° C. (“half-life decomposition temperature−2 ° C.” To “half-life decomposition temperature + 20 ° C.”). By controlling the temperature within this range with respect to the half-life decomposition temperature, the molecular weight distribution can be reduced, and the by-product of the binder polymer not having the structure of the general formula (2) can be suppressed.

  The specific binder polymer of this embodiment can be obtained by solution polymerization, suspension polymerization, emulsion polymerization, solid phase polymerization and the like. Among them, solution polymerization is preferable for obtaining a binder polymer having a weight average molecular weight of 20,000 to 300,000, and suspension polymerization is preferable for obtaining a binder polymer having a weight average molecular weight of 300,000 to 1,000,000. In addition, the polymerization method can be appropriately selected depending on the polarity and reactivity of the monomer used to obtain the binder polymer, but from the viewpoint of its solubility, a solvent-soluble acrylic polymer can be synthesized by solution polymerization. preferable.

  The solution polymerization is performed by dissolving a polymerizable monomer, a chain transfer agent, and a radical initiator in a solvent and heating to a temperature determined by the radical initiator. At this time, the polymerization can be carried out even under air, but it is preferably carried out under nitrogen. In addition, you may use the solvent which can melt | dissolve the binder polymer to produce | generate as said solvent.

  The solvent used in the solution polymerization is not particularly limited as long as it can dissolve the polymerizable monomer, the chain transfer agent, the radical initiator, and the binder polymer to be formed, but preferably has a boiling point equal to or higher than the temperature at which the polymerization is performed. . When the temperature at which the polymerization is performed is higher than the boiling point of the solvent used, the polymerization can be performed by a reaction under pressure.

  Examples of the organic solvent used for the polymerization of the binder polymer include methoxyethanol, ethoxyethanol, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanol, cyclohexanone, butyl acetate, chlorobenzene, dioxane, propylene glycol monomethyl ether, and the like. Not limited. These can be used alone or in combination.

  As the component (A), one type of specific binder polymer may be used alone, or two or more types of specific binder polymers may be used in any combination. Moreover, you may use other binder polymers other than a specific binder polymer with a specific binder polymer.

  The acid value of the binder polymer is preferably 90 mgKOH / g to 250 mgKOH / g, more preferably 100 mgKOH / g to 240 mgKOH / g, and 120 mgKOH / g to 120 mgKOH / g in terms of excellent balance between developability and adhesion. It is more preferable that it is 235 mgKOH / g, and it is especially preferable that it is 130 mgKOH / g-230 mgKOH / g. From the viewpoint of further shortening the development time, the acid value is preferably 90 mgKOH / g or more, more preferably 100 mgKOH / g or more, further preferably 120 mgKOH / g or more, and 130 mgKOH / g or more. It is particularly preferred that Further, from the viewpoint of further improving the adhesion of the cured product of the photosensitive resin composition, the acid value is preferably 250 mgKOH / g or less, more preferably 240 mgKOH / g or less, and 235 mgKOH / g or less. It is more preferable that it is 230 mgKOH / g or less.

  The weight average molecular weight (Mw) of the binder polymer is 20,000 to 100,000 in terms of excellent balance between developability and adhesion when measured by gel permeation chromatography (GPC) (converted by a calibration curve using standard polystyrene). It is preferably 23,000 to 80,000, more preferably 25,000 to 60,000. In terms of excellent developability, the weight average molecular weight is preferably 200000 or less, more preferably 100000 or less, still more preferably 80000 or less, and particularly preferably 60000 or less. In terms of excellent adhesion, the weight average molecular weight is preferably 20000 or more, more preferably 23000 or more, and further preferably 25000 or more.

  The dispersity (dispersion degree of molecular weight) of the binder polymer is preferably 1.4 or less, more preferably 1.3 or less, and further preferably 1.2 or less in view of further excellent resolution. preferable. The lower limit of the dispersity is not particularly limited, but is usually 1 or more. In the present specification, the “dispersion degree” means the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (polydispersity: Mw / Mn).

  The binder polymer may have a characteristic group in its molecule that has photosensitivity to light having a wavelength in the range of 340 nm to 430 nm, if necessary. Examples of the characteristic group include a group constituted by removing at least one hydrogen atom from a sensitizing dye described later.

  The content of the component (A) (including the specific binder polymer) in the photosensitive resin composition is 100 parts by mass of the total amount of the component (A) and the component (B) in that the film formability, sensitivity, and resolution are further improved. The content is preferably 30 parts by mass to 70 parts by mass, more preferably 35 parts by mass to 65 parts by mass, and still more preferably 40 parts by mass to 60 parts by mass. This content is preferably 30 parts by mass or more, more preferably 35 parts by mass or more, and 40 parts by mass or more from the viewpoint of further excellent formability of the film (photosensitive resin composition layer). More preferably. Further, from the viewpoint of further excellent sensitivity and resolution, the content is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, and further preferably 60 parts by mass or less.

(B) Component: Photopolymerizable Compound Next, the photopolymerizable compound (hereinafter also referred to as “component (B)”) will be described. The photopolymerizable compound as the component (B) is not particularly limited as long as it can be photopolymerized. The photopolymerizable compound is preferably a compound having an ethylenically unsaturated bond. The compound having an ethylenically unsaturated bond includes a compound having one ethylenically unsaturated bond in the molecule, a compound having two ethylenically unsaturated bonds in the molecule, and three ethylenically unsaturated bonds in the molecule. Examples thereof include the compounds described above.

  The content of the photopolymerizable compound as the component (B) in the photosensitive resin composition is such that the component (A) and the component (B) are further suppressed from the viewpoint of further suppressing swelling by suppressing molecular motion in the crosslinked network after photocuring. The total amount of the components is preferably 1 part by mass to 60 parts by mass, more preferably 5 parts by mass to 55 parts by mass, and still more preferably 10 parts by mass to 50 parts by mass.

  Examples of the compound having two ethylenically unsaturated bonds in the molecule include a bisphenol type di (meth) acrylate compound, a hydrogenated bisphenol A type di (meth) acrylate compound, and a di (meth) having a urethane bond in the molecule. Examples include acrylate compounds, polyalkylene glycol di (meth) acrylates having both (poly) oxyethylene groups and (poly) oxypropylene groups in the molecule, and trimethylolpropane di (meth) acrylate.

  The component (B) preferably contains at least one bisphenol di (meth) acrylate compound from the viewpoint of further improving the adhesion of the resist pattern. When the photosensitive resin composition contains a bisphenol type di (meth) acrylate compound as the component (B), the content thereof is 1 part by mass to 100 parts by mass of the total amount of the component (A) and the component (B). It is preferably 50 parts by mass, more preferably 5 parts by mass to 50 parts by mass, and still more preferably 10 parts by mass to 45 parts by mass.

  Among the bisphenol-type di (meth) acrylate compounds, commercially available ones include 2,2-bis (4- (methacryloxydiethoxy) phenyl) propane (Hitachi Chemical Co., Ltd., “FA-324ME”). Etc.), 2,2-bis (4- (methacryloxyethoxy) phenyl) propane (ethylene oxide average 10 mol adduct) (Hitachi Chemical Co., Ltd., “FA-321M” etc.), 2,2-bis (4- (Methacryloxyethoxypropoxy) phenyl) propane (ethylene oxide average 12 mol and propylene oxide average 4 mol adduct) (Hitachi Chemical Co., Ltd., “FA-3200MY”, etc.) and the like.

  Examples of the hydrogenated bisphenol A type di (meth) acrylate compound include 2,2-bis (4- (methacryloxypentaethoxy) cyclohexyl) propane. When the photosensitive resin composition contains a hydrogenated bisphenol A type di (meth) acrylate compound, the content thereof is 1 part by mass to 50 parts by mass in 100 parts by mass of the total amount of the component (A) and the component (B). Part, preferably 5 parts by weight to 40 parts by weight.

  Moreover, it is preferable that (B) component contains at least 1 sort (s) of polyalkylene glycol di (meth) acrylate as a photopolymerizable compound from a viewpoint of further improving the flexibility of a resist pattern. When the photosensitive resin composition contains polyalkylene glycol di (meth) acrylate, the content thereof is 5 to 30 parts by mass in 100 parts by mass of the total amount of the component (A) and the component (B). It is preferably 10 parts by mass to 25 parts by mass.

  As the polyalkylene glycol di (meth) acrylate compound, polyalkylene glycol di (meth) acrylate having both a (poly) oxyethylene group and a (poly) oxypropylene group in the molecule is preferable. In the molecule of the polyalkylene glycol di (meth) acrylate, the (poly) oxyethylene group and the (poly) oxypropylene group may be continuously present in blocks or randomly. The propylene group in the (poly) oxypropylene group may be either an n-propylene group or an isopropylene group. In the (poly) oxypropylene group having an isopropylene group, the secondary carbon of the propylene group may be bonded to an oxygen atom, or the primary carbon may be bonded to an oxygen atom.

  Polyalkylene glycol di (meth) acrylate is (poly) n-butyleneoxy group, (poly) isobutyleneoxy group, (poly) n-pentyleneoxy group, (poly) hexyleneoxy group, structural isomers thereof, etc. (Poly) alkyleneoxy group having about 4 to 6 carbon atoms.

  When the component (B) includes a photopolymerizable compound having two ethylenically unsaturated bonds in the molecule as the photopolymerizable compound, the content is 100 mass of the total amount of the component (A) and the component (B). In the part, it is preferably 5 parts by mass to 60 parts by mass, more preferably 5 parts by mass to 55 parts by mass, and still more preferably 10 parts by mass to 50 parts by mass.

  The component (B) may contain at least one photopolymerizable compound having three or more ethylenically unsaturated bonds in the molecule as the photopolymerizable compound.

  Examples of the compound having three or more ethylenically unsaturated bonds include trimethylolpropane tri (meth) acrylate and EO-modified trimethylolpropane tri (meth) acrylate (having 1 to 5 structural units of oxyethylene groups). , PO-modified trimethylolpropane tri (meth) acrylate, EO / PO-modified trimethylolpropane tri (meth) acrylate, tetramethylolmethanetri (meth) acrylate and tetramethylolmethanetetra (meth) acrylate, pentaerythritol tri (meth) acrylate EO-modified pentaerythritol tetra (meth) acrylate or dipentaerythritol hexa (meth) acrylate. These can be used alone or in combination of two or more.

  Among the compounds having three or more ethylenically unsaturated bonds, commercially available compounds include tetramethylol methane triacrylate (Shin Nakamura Chemical Co., Ltd., “A-TMM-3”, etc.), EO Modified trimethylolpropane trimethacrylate (Hitachi Chemical Co., Ltd., “TMPT21E”, “TMPT30E”, etc.), pentaerythritol triacrylate (Sartomer Co., Ltd., “SR444”, etc.), dipentaerythritol hexaacrylate (Shin Nakamura Chemical Co., Ltd.) Co., Ltd., “A-DPH”, etc.), EO-modified pentaerythritol tetraacrylate (Shin Nakamura Chemical Co., Ltd., “ATM-35E”, etc.)) and the like.

  When the component (B) contains a photopolymerizable compound having three or more ethylenically unsaturated bonds in the molecule as the photopolymerizable compound, the content is resolution, adhesion, resist shape, and peeling after curing. From the viewpoint of improving the properties in a well-balanced manner, the total amount of the (A) component and the (B) component is preferably 3 parts by mass to 30 parts by mass, and preferably 5 parts by mass to 25 parts by mass. More preferably, it is further preferably 5 to 20 parts by mass.

  The component (B) has an ethylenically unsaturated bond in the molecule as a photopolymerizable compound from the viewpoint of improving the resolution, adhesion, resist shape, and release properties after curing in a well-balanced manner, or suppressing scum generation. One photopolymerizable compound may be included.

  Examples of the photopolymerizable compound having one ethylenically unsaturated bond in the molecule include nonylphenoxy polyoxyethylene acrylate, phthalic acid compounds, and (meth) acrylic acid alkyl esters. Among the above, it is preferable that nonylphenoxy polyoxyethylene acrylate or a phthalic acid compound is included from the viewpoint of improving the resolution, adhesion, resist shape, and peeling property after curing in a well-balanced manner.

  When the component (B) contains a photopolymerizable compound having one ethylenically unsaturated bond in the molecule as the photopolymerizable compound, the content is 100 mass of the total amount of the component (A) and the component (B). In the part, it is preferably 1 part by mass to 20 parts by mass, more preferably 3 parts by mass to 15 parts by mass, and still more preferably 5 parts by mass to 12 parts by mass.

  The total content of component (B) in the photosensitive resin composition is preferably 30 parts by mass to 70 parts by mass with respect to 100 parts by mass of the total amount of component (A) and component (B), and 35 parts by mass to More preferably, it is 65 mass parts, and it is still more preferable that it is 35 mass parts-50 mass parts. When the content is 30 parts by mass or more, sufficient sensitivity and resolution tend to be easily obtained. When it is 70 parts by mass or less, a film (photosensitive resin composition layer) tends to be easily formed, and a good resist shape tends to be easily obtained.

Component (C): Photopolymerization initiator The photosensitive resin composition contains at least one photopolymerization initiator as the component (C). There is no restriction | limiting in particular as a photoinitiator which is (C) component, It can select suitably from the photoinitiator used normally. As the photopolymerization initiator, benzophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino- Aromatic ketones such as 1-propanone; quinone compounds such as alkylanthraquinones; benzoin ether compounds such as benzoin alkyl ethers; benzoin compounds such as benzoin and alkylbenzoins; benzyl derivatives such as benzyldimethyl ketal; 2- (2-chlorophenyl)- 4,5-diphenylimidazole dimer (eg, 2,2′-bis (2-chlorophenyl) -4,4 ′, 5,5′-tetraphenylbisimidazole), 2- (2-fluorophenyl) -4 2,4,5-triarylimid such as 1,5-diphenylimidazole dimer Tetrazole dimer; 9-phenyl acridine, 1,7 (9,9'-acridinyl) including acridine derivatives heptane, and the like. These can be used alone or in combination of two or more.

  The component (C) preferably contains at least one 2,4,5-triarylimidazole dimer from the viewpoint of further improving sensitivity and adhesion, and 2- (2-chlorophenyl) -4,5 -More preferably, it contains a diphenylimidazole dimer. The 2,4,5-triarylimidazole dimer may be symmetric or asymmetric in structure.

  The content of the component (C) in the photosensitive resin composition is preferably 0.1 parts by mass to 10 parts by mass with respect to 100 parts by mass of the total amount of the components (A) and (B). It is more preferably ˜7 parts by mass, still more preferably 2 to 6 parts by mass, and particularly preferably 3 to 5 parts by mass. When the content of the component (C) is 0.1 parts by mass or more, good sensitivity, resolution, or adhesion tends to be obtained, and when it is 10 parts by mass or less, a good resist shape can be obtained. It tends to be easier.

(D) component: Sensitizing dye It is preferable that the photosensitive resin composition contains at least 1 sort (s) of a sensitizing dye as (D) component. The sensitizing dye is capable of effectively utilizing the absorption wavelength of actinic rays used for exposure, and is preferably a compound having a maximum absorption wavelength of 340 nm to 420 nm.

  Examples of sensitizing dyes include pyrazoline compounds, anthracene compounds, coumarin compounds, xanthone compounds, oxazole compounds, benzoxazole compounds, thiazole compounds, benzothiazole compounds, triazole compounds, stilbene compounds, triazine compounds, thiophene compounds, and naphthalimide compounds. It is done. In particular, it is preferable to include a pyrazoline compound or an anthracene compound from the viewpoint of further improving resolution, adhesion, and sensitivity. (D) The sensitizing dye which is a component can be used individually by 1 type or in combination of 2 or more types.

  When the photosensitive resin composition contains the component (D), the content of the component (D) in the photosensitive resin composition is 0.01 with respect to 100 parts by mass of the total amount of the components (A) and (B). The mass is preferably 10 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, and still more preferably 0.1 to 3 parts by mass. When the content is 0.01 parts by mass or more, sensitivity and resolution tend to be easily obtained. When the content is 10 parts by mass or less, a sufficiently good resist shape tends to be easily obtained.

Component (E): Hydrogen donor The photosensitive resin composition has an excellent contrast (also referred to as “imaging property”) between the exposed portion (exposed portion) and the unexposed portion (unexposed portion). It is preferable to contain at least one hydrogen donor capable of supplying hydrogen to the photopolymerization initiator during the reaction of the exposed part as a component. Examples of the hydrogen donor include bis [4- (dimethylamino) phenyl] methane, bis [4- (diethylamino) phenyl] methane, and leucocrystal violet. These can be used alone or in combination of two or more.

  When the photosensitive resin composition contains the component (E), the content is preferably 0.01 parts by mass to 10 parts by mass with respect to 100 parts by mass of the total amount of the component (A) and the component (B). 0.05 parts by mass to 5 parts by mass is more preferable, and 0.1 parts by mass to 2 parts by mass is even more preferable. When this content is 0.01 parts by mass or more, sufficient sensitivity tends to be obtained. If the amount is 10 parts by mass or less, after the film is formed, precipitation of excess (E) component as foreign matter tends to be suppressed.

(Other ingredients)
If necessary, the photosensitive resin composition includes a photopolymerizable compound (such as an oxetane compound) having at least one cationically polymerizable cyclic ether group in the molecule, a cationic polymerization initiator, malachite green, Victoria pure blue, and brilliant. Green, dyes such as methyl violet, photochromic agents such as tribromophenylsulfone, diphenylamine, benzylamine, triphenylamine, diethylaniline, 2-chloroaniline, thermochromic inhibitors, plasticizers such as 4-toluenesulfonamide, Pigments, fillers, antifoaming agents, flame retardants, stabilizers, adhesion-imparting agents, leveling agents, peeling accelerators, antioxidants, fragrances, imaging agents, thermal crosslinking agents, and the like may be included. These are used alone or in combination of two or more. When the photosensitive resin composition contains other components, these contents are about 0.01 parts by mass to 20 parts by mass with respect to 100 parts by mass of the total amount of the component (A) and the component (B), respectively. It is preferable.

[Solution of photosensitive resin composition]
The photosensitive resin composition of this embodiment may further contain at least one organic solvent in order to adjust the viscosity as necessary. Organic solvents include alcohol solvents such as methanol and ethanol; ketone solvents such as acetone and methyl ethyl ketone; glycol ether solvents such as methyl cellosolve, ethyl cellosolve, and propylene glycol monomethyl ether; aromatic hydrocarbon solvents such as toluene; N, N- And aprotic polar solvents such as dimethylformamide. These may be used alone or in combination of two or more. The content of the organic solvent contained in the photosensitive resin composition can be appropriately selected depending on the purpose and the like. For example, the photosensitive resin composition can be used as a solution having a solid content of about 30% by mass to 60% by mass. Hereinafter, the photosensitive resin composition containing the organic solvent is also referred to as “coating liquid”.

  A photosensitive resin composition layer can be formed using the photosensitive resin composition by applying (for example, applying) the coating liquid onto the surface of a support, a metal plate, or the like described later and drying it. . It does not restrict | limit especially as a metal plate, According to the objective etc., it can select suitably. Examples of the metal plate include metal plates such as copper, copper-containing alloys, iron-containing alloys such as nickel, chromium, iron, and stainless steel. As a metal plate, Preferably, metal plates, such as copper, a copper containing alloy, and an iron containing alloy, are mentioned.

  The thickness of the photosensitive resin composition layer to be formed is not particularly limited and can be appropriately selected depending on the application. For example, the thickness after drying is preferably 1 μm to 100 μm. When the photosensitive resin composition layer is formed on the metal plate, the surface of the photosensitive resin composition layer opposite to the metal plate may be covered with a protective layer. Examples of the protective layer include polymer films such as polyethylene and polypropylene.

  The photosensitive resin composition can be applied to the formation of the photosensitive resin composition layer of the photosensitive element described later. That is, another embodiment of the present invention provides a photosensitive resin composition containing a specific binder polymer having a structural unit derived from (meth) acrylic acid, a photopolymerizable compound, and a photopolymerization initiator. Application to sex elements.

  Moreover, the photosensitive resin composition of this embodiment can be used for the formation method of the resist pattern mentioned later. That is, another embodiment of the present invention provides a resist of a photosensitive resin composition containing a specific binder polymer having a structural unit derived from (meth) acrylic acid, a photopolymerizable compound, and a photopolymerization initiator. This is an application to a pattern formation method.

<Photosensitive element>
The photosensitive element of this embodiment includes a support and a photosensitive resin composition layer formed on the support and formed from the photosensitive resin composition. The photosensitive resin composition layer may be a coating film. The coating film as used herein refers to a film in which the photosensitive resin composition is in an uncured state. The photosensitive element may have other layers, such as a protective layer, as needed.

  FIG. 1 shows an embodiment of a photosensitive element. In the photosensitive element 1 shown in FIG. 1, the support body 2, the photosensitive resin composition layer 3 formed from the photosensitive resin composition, and the protective layer 4 are laminated | stacked in this order. The photosensitive element 1 can be obtained as follows, for example. A coating liquid (that is, a photosensitive resin composition containing an organic solvent) is applied on the support 2 to form a coating layer, which is dried to form the photosensitive resin composition layer 3. Next, the surface of the photosensitive resin composition layer 3 opposite to the support 2 is covered with a protective layer 4, thereby supporting the support 2 and the photosensitive resin composition layer 3 formed on the support 2. And the photosensitive element 1 of this embodiment provided with the protective layer 4 laminated | stacked on this photosensitive resin composition layer 3 is obtained. The photosensitive element 1 does not necessarily have to include the protective layer 4.

  As the support, a polymer film having heat resistance and solvent resistance such as polyester such as polyethylene terephthalate, polyolefin such as polypropylene and polyethylene can be used.

  The thickness of the support (polymer film) is preferably 1 μm to 100 μm, more preferably 5 μm to 50 μm, and still more preferably 5 μm to 30 μm. It can suppress that a support body is torn when peeling a support body because the thickness of a support body is 1 micrometer or more. Moreover, the fall of the resolution is suppressed because it is 100 micrometers or less.

  As a protective layer, the thing with the adhesive force with respect to the photosensitive resin composition layer smaller than the adhesive force with respect to the photosensitive resin composition layer of a support body is preferable. Also, a low fish eye film is preferred. Here, “fish eye” means that when a material is heat-melted, kneaded, extruded, biaxially stretched, casting method, etc., foreign materials, undissolved materials, oxidatively deteriorated materials, etc. are present in the film. It means what was taken in. That is, the “low fish eye” means that there are few foreign matters in the film.

  Specifically, a polymer film having heat resistance and solvent resistance such as polyester such as polyethylene terephthalate, polyolefin such as polypropylene and polyethylene can be used as the protective layer. Commercially available products include polypropylene films such as Oji Paper's Alphan MA-410 and E-200, Shin-Etsu Film Co., Ltd., and PS series polyethylene terephthalate films such as Teijin's PS-25. It is done. The protective layer 4 may be the same as the support 2.

  The thickness of the protective layer is preferably 1 μm to 100 μm, more preferably 5 μm to 50 μm, still more preferably 5 μm to 30 μm, and particularly preferably 15 μm to 30 μm. When the thickness of the protective layer is 1 μm or more, the protective layer can be prevented from being broken when the photosensitive resin composition layer and the support are laminated on the substrate while peeling off the protective layer. When it is 100 μm or less, it is excellent in handleability and inexpensiveness.

  Specifically, the photosensitive element of this embodiment can be manufactured as follows, for example. (A) component: binder polymer, (B) component: photopolymerizable compound, and (C) a step of preparing a coating solution in which a photopolymerization initiator is dissolved in an organic solvent, and applying the coating solution on a support ( For example, it can be manufactured by a manufacturing method including a step of forming a coating layer by coating and a step of drying the coating layer to form a photosensitive resin composition layer.

  Application of the solution of the photosensitive resin composition onto the support can be performed by a known method such as roll coating, comma coating, gravure coating, air knife coating, die coating, or bar coating.

  The drying of the coating layer is not particularly limited as long as at least a part of the organic solvent can be removed from the coating layer. For example, it is preferably dried at 70 ° C. to 150 ° C. for 5 minutes to 30 minutes. After drying, the amount of the remaining organic solvent in the photosensitive resin composition layer is preferably 2% by mass or less from the viewpoint of preventing diffusion of the organic solvent in the subsequent step.

  The thickness of the photosensitive resin composition layer in the photosensitive element can be appropriately selected depending on the application. The thickness after drying is preferably 1 μm to 100 μm, more preferably 1 μm to 50 μm, and still more preferably 5 μm to 40 μm. Industrial coating becomes easy because the thickness of the photosensitive resin composition layer is 1 μm or more. When it is 100 μm or less, adhesion and resolution tend to be sufficiently obtained.

  The transmittance of the photosensitive resin composition layer with respect to ultraviolet rays is preferably 5% to 75%, more preferably 10% to 65%, more preferably 15% to ultraviolet light in the wavelength range of 350 nm to 420 nm. More preferably, it is 55%. When the transmittance is 5% or more, sufficient adhesion tends to be obtained. If it is 75% or less, sufficient resolution tends to be easily obtained. The transmittance can be measured with a UV spectrometer. An example of the UV spectrometer is a 228A type W beam spectrophotometer manufactured by Hitachi, Ltd.

  The photosensitive element may further include an intermediate layer such as a cushion layer, an adhesive layer, a light absorption layer, and a gas barrier layer. As these intermediate layers, for example, the intermediate layers described in JP-A-2006-098982 can also be applied in the present invention.

  The form of the obtained photosensitive element is not particularly limited. For example, a sheet shape may be sufficient, and the shape wound up by the roll shape on the core may be sufficient. When it winds up in roll shape, it is preferable to wind up so that a support body may become an outer side. Examples of the winding core include plastics such as polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl chloride resin, and ABS resin (acrylonitrile-butadiene-styrene copolymer). From the viewpoint of end face protection, it is preferable to install an end face separator on the end face of the roll-shaped photosensitive element roll thus obtained, and it is preferable to install a moisture-proof end face separator from the standpoint of edge fusion resistance. As a packaging method, it is preferable to wrap and package in a black sheet with low moisture permeability.

  The photosensitive element of this embodiment can be used suitably for the formation method of the resist pattern mentioned later, for example.

<Method for forming resist pattern>
A resist pattern can be formed using the photosensitive resin composition. The resist pattern forming method of this embodiment includes (i) a photosensitive layer forming step of forming a photosensitive resin composition layer on the substrate using the photosensitive resin composition, and (ii) the photosensitive resin composition. An exposure step of irradiating at least a part of the physical layer with actinic rays and photocuring the region to form a cured product region; and (iii) other than the cured product region of the photosensitive resin composition layer. A development step of removing the region from the substrate and forming a resist pattern as the cured product region on the substrate. The method for forming the resist pattern may further include other steps as necessary, and the photosensitive resin composition layer in the photosensitive layer forming step may be a coating film.

(I) Photosensitive layer formation process First, the photosensitive resin composition layer is formed on a board | substrate using the said photosensitive resin composition. As the substrate, a substrate (circuit forming substrate) including an insulating layer and a conductor layer formed on the insulating layer can be used.

  For example, when the photosensitive element 1 has the protective layer 4, the photosensitive resin composition layer is formed on the substrate after the protective layer 4 is removed and then the photosensitive resin of the photosensitive element 1. This is performed by pressure-bonding the composition layer 3 to the substrate while heating. Thereby, the laminated body by which a board | substrate, the photosensitive resin composition layer 3, and the support body 2 are laminated | stacked in this order is obtained.

This photosensitive layer forming step is preferably performed under reduced pressure from the viewpoint of adhesion and followability. Heating at least one of the photosensitive resin composition layer and the substrate during the pressure bonding is preferably performed at a temperature of 70 ° C. to 130 ° C., and is about 0.1 MPa to 1.0 MPa (1 kgf / cm ^{2 to} 10 kgf / cm ^2. It is preferable to press-fit with a pressure of about). These conditions are not particularly limited, and are appropriately selected as necessary. In addition, if the photosensitive resin composition layer is heated to 70 ° C. to 130 ° C., the substrate need not be preheated in advance. Adhesion and follow-up can be further improved by pre-heat treatment of the circuit forming substrate.

(Ii) Exposure step In the exposure step, the exposed portion irradiated with actinic rays is irradiated with actinic rays by irradiating at least a part of the photosensitive resin composition layer formed on the substrate as described above. It is photocured to form a latent image. Under the present circumstances, when the support body which exists on the photosensitive resin composition layer is transparent with respect to actinic light, actinic light can be irradiated through a support body. On the other hand, when the support is light-shielding against actinic rays, the photosensitive resin composition layer is irradiated with actinic rays after the support is removed.

  Examples of the exposure method include a method of irradiating an actinic ray in an image form through a negative or positive mask pattern called an artwork (mask exposure method). Alternatively, a method of irradiating actinic rays in an image form by a direct drawing exposure method such as an LDI (Laser Direct Imaging) exposure method or a DLP (Digital Light Processing) exposure method may be employed.

  The light source for actinic rays is not particularly limited, and a known light source can be used. For example, effective use of ultraviolet light, visible light, etc. such as carbon arc lamp, mercury vapor arc lamp, high pressure mercury lamp, xenon lamp, gas laser such as argon laser, solid state laser such as YAG laser, blue-violet laser such as semiconductor laser and gallium nitride What emits is used.

  The wavelength of the actinic ray (exposure wavelength) is preferably in the range of 340 nm to 430 nm, and more preferably in the range of 350 nm to 420 nm, from the viewpoint of obtaining the effect of the present invention more reliably.

(Iii) Development Step In the development step, the uncured portion of the photosensitive resin composition layer is removed from the circuit forming substrate by a development process, whereby the photosensitive resin composition layer is a photocured cured product. A pattern is formed on the substrate. When a support is present on the photosensitive resin composition layer, the support is removed, and then removal (development) of the unexposed portion is performed. Development processing includes wet development and dry development, and wet development is widely used.

  In the case of wet development, development is performed by a known development method using a developer corresponding to the photosensitive resin composition. Examples of the developing method include a method using a dipping method, a paddle method, a spray method, brushing, slapping, scrubbing, rocking immersion, and the like. From the viewpoint of improving resolution, a high pressure spray method is preferable. You may develop by combining these 2 or more types of methods.

  A developing solution is suitably selected according to the structure of the photosensitive resin composition. Examples of the developer include an alkaline aqueous solution and an organic solvent developer.

  The alkaline aqueous solution is safe and stable when used as a developer, and has good operability. Examples of the base of the alkaline aqueous solution include alkali hydroxides such as lithium, sodium, or potassium hydroxide; alkali carbonates such as lithium, sodium, potassium, or ammonium carbonate or bicarbonate; potassium phosphate, sodium phosphate, and the like. Alkali metal phosphates; alkali metal pyrophosphates such as sodium pyrophosphate and potassium pyrophosphate, borax (sodium tetraborate), sodium metasilicate, tetramethylammonium hydroxide, ethanolamine, ethylenediamine, diethylenetriamine, 2 -Amino-2-hydroxymethyl-1,3-propanediol, 1,3-diamino-2-propanol, morpholine and the like are used.

  Examples of the alkaline aqueous solution used for development include a dilute solution of 0.1% by mass to 5% by mass of sodium carbonate, a dilute solution of 0.1% by mass to 5% by mass of potassium carbonate, and 0.1% by mass to 5% by mass of sodium hydroxide. A dilute solution of 0.1 mass% to 5 mass% of sodium tetraborate is preferred. The pH of the alkaline aqueous solution is preferably in the range of 9-11. Moreover, the temperature is adjusted according to the alkali developability of the photosensitive resin composition layer. In the alkaline aqueous solution, a surfactant, an antifoaming agent, a small amount of an organic solvent for promoting development, and the like may be mixed.

  The alkaline aqueous solution may contain one or more organic solvents. Examples of the organic solvent to be used include acetone, ethyl acetate, alkoxyethanol having an alkoxy group having 1 to 4 carbon atoms, ethyl alcohol, isopropyl alcohol, butyl alcohol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, and the like. . These are used alone or in combination of two or more. When the organic solvent is included, the content of the organic solvent is preferably 2% by mass to 90% by mass based on the alkaline aqueous solution. Moreover, the temperature can be adjusted according to alkali developability. A small amount of a surfactant, an antifoaming agent or the like may be mixed in the alkaline aqueous solution used for development.

  Examples of the organic solvent used in the organic solvent developer include 1,1,1-trichloroethane, N-methylpyrrolidone, N, N-dimethylformamide, cyclohexanone, methyl isobutyl ketone, and γ-butyrolactone. It is preferable to add an organic solvent developer to these organic solvents in order to prevent ignition by adding water in the range of 1% by mass to 20% by mass.

The method for forming a resist pattern, by performing exposure after removing unexposed portions, energy heating or 0.2J ^/ cm ² ~10J ^/ cm 2 of 60 ° C. to 250 DEG ° C. If necessary, the resist A step of further curing the pattern may be further included.

<Method for manufacturing printed wiring board>
The method for manufacturing a printed wiring board according to the present embodiment includes a step of etching or plating the substrate on which the resist pattern is formed by the resist pattern forming method. The method for manufacturing a printed wiring board according to the present embodiment includes, for example, forming the resist pattern on the conductive layer of a substrate (circuit forming substrate) including an insulating layer and a conductive layer formed on the insulating layer. It includes a step of forming a conductor pattern by etching or plating the substrate on which the resist pattern is formed by the method. The manufacturing method of a printed wiring board may include other processes, such as a resist removal process, as needed. Etching or plating of the substrate is performed on the conductor layer of the substrate using the formed resist pattern as a mask.

  In the etching process, using the resist pattern (cured resist) formed on the substrate as a mask, the conductor layer of the circuit forming substrate not covered with the cured resist is removed by etching to form a conductor pattern. The etching method is appropriately selected according to the conductor layer to be removed. Examples of the etching solution include a cupric chloride aqueous solution, a ferric chloride aqueous solution, an alkali etching solution, and a hydrogen peroxide etching solution. Among these, it is preferable to use a ferric chloride aqueous solution because it has a good etch factor.

  On the other hand, in the plating process, copper, solder, or the like is plated on the conductor layer of the circuit forming substrate that is not covered with the cured resist, using the resist pattern (cured resist) formed on the substrate as a mask. After the plating treatment, the hardened resist is removed, and the conductor layer covered with the hardened resist is etched to form a conductor pattern. The method of plating treatment may be electrolytic plating treatment or electroless plating treatment. The plating treatment includes copper plating such as copper sulfate plating and copper pyrophosphate plating, solder plating such as high-throw solder plating, watt bath (nickel sulfate-nickel chloride) plating, nickel plating such as nickel sulfamate, hard gold plating, and soft plating. Examples thereof include gold plating such as gold plating.

  After the etching process and the plating process, the resist pattern on the substrate is removed (peeled). The removal of the resist pattern can be performed, for example, using a stronger alkaline aqueous solution than the alkaline aqueous solution used in the development step. As this strongly alkaline aqueous solution, a 1% by mass to 10% by mass sodium hydroxide aqueous solution, a 1% by mass to 10% by mass potassium hydroxide aqueous solution and the like are used. Among these, it is preferable to use a 1% by mass to 10% by mass sodium hydroxide aqueous solution or a 1% by mass to 10% by mass potassium hydroxide aqueous solution, and a 1% by mass to 5% by mass sodium hydroxide aqueous solution or 1% by mass to 5% by mass water. It is more preferable to use an aqueous potassium oxide solution. Examples of the method of applying a strong alkaline aqueous solution to the resist pattern include an immersion method and a spray method. These may be used alone or in combination of two or more.

  When the resist pattern is removed after the plating process, a desired printed wiring board can be manufactured by further removing the conductor layer covered with the cured resist by the etching process and forming the conductor pattern. The etching method is appropriately selected according to the conductor layer to be removed. For example, the above-described etching solution can be applied.

  The printed wiring board manufacturing method of the present embodiment can be applied not only to a single-layer printed wiring board but also to a multilayer printed wiring board, and also to a printed wiring board having a small-diameter through hole. It is.

  The photosensitive resin composition of this embodiment can be used suitably for manufacture of a wiring board. That is, one preferred embodiment of the present invention is a photosensitive resin composition comprising a specific binder polymer having a structural unit derived from (meth) acrylic acid, a photopolymerizable compound, and a photopolymerization initiator. This is an application to the production of printed wiring boards.

  A more preferred embodiment is the application of the photosensitive resin composition to the production of a high-density package substrate, and the application of the photosensitive resin composition to a semi-additive construction method. Below, an example of the manufacturing process of the wiring board by a semi-additive construction method is demonstrated, referring drawings.

  In FIG. 2A, a substrate (circuit forming substrate) in which the conductor layer 10 is formed on the insulating layer 15 is prepared. The conductor layer 10 is, for example, a metal copper layer. In FIG. 2B, the photosensitive resin composition layer 32 is formed on the conductor layer 10 of the substrate by the photosensitive layer forming step. In FIG.2 (c), the mask 20 is arrange | positioned on the photosensitive resin composition layer 32, the active light ray 50 is irradiated to the photosensitive resin composition layer 32 by the said exposure process, and the area | region where the mask 20 was arrange | positioned. A region other than the above is exposed to form a photocured portion in the photosensitive resin composition layer 32. In FIG. 2D, the resist pattern 30 which is a photocuring part is formed on a board | substrate by removing area | regions other than a photocuring part in the photosensitive resin composition layer 32 from a board | substrate by a image development process. In FIG. 2E, a plating layer 42 is formed on the conductor layer 10 by plating using the resist pattern 30 that is a photocured portion as a mask. In FIG. 2F, after the resist pattern 30 which is a photocured portion is peeled off with a strong alkaline aqueous solution, a part of the plating layer 42 and the conductor layer 10 masked by the resist pattern 30 are removed by flash etching. The circuit pattern 40 is formed by removing. The conductor layer 10 and the plating layer 42 may be made of the same material or different materials. Although the method of forming the resist pattern 30 using the mask 20 has been described with reference to FIG. 2, the resist pattern 30 may be formed by direct drawing exposure without using the mask 20.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

<Synthesis of binder polymer>
[Synthesis of Binder Polymer (A-1)]
In a 500 mL separable flask equipped with a reflux condenser, a thermometer, a stirrer, and a nitrogen gas introduction tube, 27 g of methacrylic acid as a polymerizable monomer (monomer), 28 g of benzyl methacrylate and 45 g of styrene (mass ratio 27/28) / 45), 1.24 g of cumyldithiobenzoate, and 0.15 g of azobisisobutyronitrile were added and mixed to obtain “solution a”.

  Next, the solution a in the flask was bubbled with nitrogen at room temperature and stirred for 30 minutes. In addition, the room temperature as used in the field of this invention means 25 degreeC.

  The temperature was then raised to 65 ° C. and stirred for 30 minutes, after which the temperature was raised to 70 ° C. and stirred for 2 hours.

  When the viscosity of the reaction solution increased, 46 g of a propylene glycol monomethyl ether / toluene (mass ratio 3/2) mixture that had been bubbled with nitrogen for 30 minutes was added and stirred for another 2 hours.

  The reaction solution was cooled and then poured into 1 L of hexane to collect a precipitate, which was vacuum dried at 70 ° C. for 2 hours. Dissolve the solid in 120 g of a propylene glycol monomethyl ether / toluene (mass ratio 3/2) mixture and add 0.6 g of azobisisobutyronitrile at 75 ° C. until the color of the solution turns from pink to light yellow. Stir.

  After cooling, the reaction solution was poured into 1 L of hexane, and the precipitate was collected and dried in vacuo at 70 ° C. for 2 hours. The solid was dissolved in a propylene glycol monomethyl ether / toluene (mass ratio 3/2) mixture so that the solid content was 40% to obtain a solution of the binder polymer (A-1).

  The weight average molecular weight of the binder polymer (A-1) was 32000, and the degree of dispersion was 1.2.

  In addition, the weight average molecular weight and the number average molecular weight were measured by gel permeation chromatography (GPC), and were derived by conversion using a standard polystyrene calibration curve. The GPC conditions are shown below.

GPC condition Pump: Hitachi L-6000 type (Hitachi, Ltd.)
Column: 3 in total, column specifications: 10.7 mmφ x 300 mm
Gelpack GL-R440
Gelpack GL-R450
Gelpack GL-R400M (Hitachi Chemical Co., Ltd.)
Eluent: Tetrahydrofuran (THF)
Sample concentration: 120 mg of a binder polymer solution having a solid content of 41.2% by mass was sampled and dissolved in 5 mL of THF to prepare a sample.
Measurement temperature: 40 ° C
Injection volume: 200 μL
Pressure: 49Kgf / cm ² (4.8MPa)
Flow rate: 2.05 mL / min Detector: Hitachi L-3300 type RI (Hitachi, Ltd.)

[Synthesis of Binder Polymer (A-2)]
Polymerizable monomer (monomer) 60 g of methacrylic acid, 210 g of benzyl methacrylate and 30 g of methyl methacrylate (mass ratio 20/70/10), 1.24 g of cumyl dithiobenzoate, azobisisobutyronitrile 1 The solution obtained by mixing 0.0 g with this was designated as “solution b”, and the solution of the binder polymer (A-1) was used in the same manner as in the case of obtaining the solution of the binder polymer (A-1) except that the solution b was used instead of the solution a. A solution of A-2) was obtained. The weight average molecular weight of the binder polymer (A-2) was 31000, and the degree of dispersion was 1.2.

[Synthesis of Binder Polymer (A-3)]
A polymerizable monomer (monomer) of 81 g of methacrylic acid, 69 g of benzyl methacrylate, 135 g of styrene and 15 g of methyl methacrylate (mass ratio 27/23/45/5) and 1.5 g of azobisisobutyronitrile. The solution obtained by mixing was designated as “Solution c”.

  A solution obtained by dissolving 0.5 g of azobisisobutyronitrile in 100 g of a mixed solution of 60 g of methyl cellosolve and 40 g of toluene (mass ratio 3/2) was designated as “Solution d”.

  Into a flask equipped with a stirrer, reflux condenser, thermometer, dropping funnel and nitrogen gas inlet tube, 180 g of methyl cellosolve and 120 g of toluene (mass ratio 3/2) 300 g of a mixed solution were charged, and nitrogen gas was blown into the flask. While stirring, the mixture was heated to 80 ° C.

  The solution c was added dropwise to the mixed solution in the flask over a period of 4 hours at a constant dropping rate, and then stirred at 80 ° C. for 2 hours. Next, the solution d was dropped into the solution in the flask at a constant dropping rate over 10 minutes, and then the solution in the flask was stirred at 80 ° C. for 3 hours. Further, the solution in the flask was heated to 90 ° C. with stirring over 30 minutes, stirred at 90 ° C. for 2 hours, then cooled to room temperature to stop stirring, and the solution of the binder polymer (A-3) was Obtained. The weight average molecular weight of the binder polymer (A-3) was 44000, and the degree of dispersion was 2.2.

[Synthesis of Binder Polymer (A-4)]
A polymerizable monomer (monomer) obtained by mixing 60 g of methacrylic acid, 210 g of benzyl methacrylate and 30 g of methyl methacrylate (mass ratio 20/70/10) and 1.0 g of azobisisobutyronitrile. The solution of the binder polymer (A-4) was obtained in the same manner as the solution of the binder polymer (A-3) except that the solution was changed to “solution e” and the solution e was used instead of the solution c. . The weight average molecular weight of the binder polymer (A-4) was 44000, and the degree of dispersion was 2.2.

  Table 1 shows the mass ratio (%) of the polymerizable monomer (monomer), the weight average molecular weight, the degree of dispersion, and the polymerization method for the binder polymers (A-1) to (A-4).

<Preparation of solution of photosensitive resin composition>
By mixing the components (A) to (E) and the dyes shown in Tables 2 and 3 with the compounding amounts (unit: g) shown in the same table together with 9 g of acetone, 5 g of toluene and 5 g of methanol, Examples 1 to 3 were used. The solutions of the photosensitive resin compositions of Reference Example 4 and Comparative Examples 1 to 4 were prepared. The blending amount of the component (A) shown in Tables 2 and 3 is a mass part (solid content) of nonvolatile content. Details of each component shown in Tables 2 and 3 are as follows. “-” Means not blended.

(A) Binder polymer Binder polymers (A-1) to (A-4) synthesized as described above were used.

(B) Photopolymerizable compound FA-321M: 2,2-bis (4- (methacryloxyethoxy) phenyl) propane (ethylene oxide average 10 mol adduct) (Hitachi Chemical Co., Ltd., “FA-321M”)
FA-324ME: 2,2-bis (4- (methacryloxydiethoxy) phenyl) propane (Hitachi Chemical Co., Ltd., “FA-324ME”)
FA-3200MY: 2,2-bis (4- (methacryloxyethoxypropoxy) phenyl) propane (ethylene oxide average 12 mol and propylene oxide average 4 mol adduct) (Hitachi Chemical Co., Ltd., “FA-3200MY”)
FA-024M: (PO) (EO) (PO) -modified dimethacrylate (addition product of ethylene oxide average 6 mol and propylene oxide average 12 mol) (Hitachi Chemical Co., Ltd., “FA-024M”)
FA-MECH: (2-hydroxy-3-chloro) propyl-2-methacryloyloxyethyl phthalate (Hitachi Chemical Co., Ltd., “FA-MECH”)
TMPT21E: EO-modified trimethylolpropane trimethacrylate (21 mol adduct with an average of ethylene oxide) (Hitachi Chemical Co., Ltd., “TMPT21E”)

(C) Photopolymerization initiator B-CIM: 2,2′-bis (2-chlorophenyl) -4,4 ′, 5,5′-tetraphenylbisimidazole [2- (2-chlorophenyl) -4,5 -Diphenylimidazole dimer] (Hampford, “B-CIM”)

(D) Sensitizing dye DBA: 9,10-dibutoxyanthracene ("DBA", Kawasaki Chemical Industry Co., Ltd.)
PYR-1: 1-phenyl-3- (4-methoxystyryl) -5- (4-methoxyphenyl) pyrazoline (Nippon Chemical Industry Co., Ltd., “PYR-1”)

(E) Hydrogen donor LCV: Leuco Crystal Violet (Yamada Chemical Co., Ltd., “LCV”)

Dye ・ MKG: Malachite Green (Osaka Organic Chemical Industry Co., Ltd., “MKG”)

<Production of photosensitive element>
The photosensitive resin composition solution obtained above was applied on a 16 μm thick polyethylene terephthalate film (Toray Industries, Inc., “FB-40”) (support) so that the thickness was uniform, The photosensitive resin composition layer having a dried film thickness of 25 μm was formed by sequentially drying with a hot air convection dryer at 70 ° C. and 110 ° C. A polypropylene film (Oji Paper Co., Ltd., “E-200K”) (protective layer) is laminated on the photosensitive resin composition layer, and a support, a photosensitive resin composition layer, and a protective layer are laminated in this order. The obtained photosensitive element was obtained.

<Production of laminated substrate>
A copper-clad laminate (Hitachi Chemical Co., Ltd., “MCL-E-679F”) (hereinafter referred to as “substrate”) having a glass epoxy material and copper foil (thickness 16 μm) formed on both surfaces thereof. After heating to 80 ° C. and using the photosensitive elements according to Examples 1 to 3, Reference Example 4 and Comparative Examples 1 to 4, a photosensitive resin composition layer was formed on the copper surface of the substrate. Was formed (laminated). Lamination was performed under conditions of a temperature of 120 ° C. and a lamination pressure of 4 kgf / cm ² (0.4 MPa) so that the photosensitive resin composition layer of each photosensitive element was in close contact with the copper surface of the substrate while removing the protective layer. Went under. Thus, the laminated substrate by which the photosensitive resin composition layer and the support body were laminated | stacked on the copper surface of the board | substrate was obtained.

The obtained laminated substrate was allowed to cool to 23 ° C. Next, a 41-step tablet having a density region of 0.00 to 2.00, a density step of 0.05, a tablet size of 20 mm × 187 mm, and a size of each step of 3 mm × 12 mm on the support of the laminated substrate. A photo tool having Using a direct-drawing exposure machine (Hitachi Via Mechanics Co., Ltd., “DE-1UH”) with a blue-violet laser diode having a wavelength of 405 nm as a light source, a photo tool and support with an energy amount (exposure amount) of 100 mJ / cm ² The photosensitive resin composition layer was exposed through the body. For measurement of illuminance, an ultraviolet illuminance meter (USHIO INC., “UIT-150”) to which a 405 nm probe was applied was used.

<Evaluation of sensitivity>
After the exposure, the support was peeled from the laminated substrate to expose the photosensitive resin composition layer, and developed by spraying a 1% by mass aqueous sodium carbonate solution at 30 ° C. for 60 seconds to remove unexposed portions. Thus, the resist pattern which is the hardened | cured material of the photosensitive resin composition was formed on the copper surface of a board | substrate. The sensitivity of the photosensitive resin composition was evaluated by measuring the number of remaining steps (step number) of the step tablet obtained as a resist pattern (cured film). The sensitivity is indicated by the number of step steps, and the higher the step number, the better the sensitivity. The results are shown in Tables 4 and 5.

<Evaluation of resolution>
Using a drawing pattern with a line width (L) / space width (S) (L / S) of 3/3 to 30/30 (unit: μm), the energy at which the number of remaining stages of the 41-step tablet becomes 15 steps The photosensitive resin composition layer of the laminated substrate was exposed (drawn) in an amount. After the exposure, the same development processing as in the sensitivity evaluation was performed.

  After development, the space portion (unexposed portion) is removed cleanly, and the line portion (exposed portion) of the line width / space width value of the resist pattern formed without causing defects such as meandering and chipping. The resolution was evaluated by the minimum value. The smaller this value, the better the resolution. In addition, the obtained resist pattern was confirmed to be defective by magnifying and observing at a magnification of 1000 times using a microscope. The results are shown in Tables 4 and 5.

  As apparent from Tables 4 and 5, the binder polymer having a structural unit derived from (meth) acrylic acid and a photopolymerizable compound, the binder polymer has a weight average molecular weight of 20000 or more, and the binder polymer It was found that by using a photosensitive resin composition that is a polymer obtained by reversible addition-fragmentation chain transfer polymerization, a resist pattern with excellent resolution can be formed compared to the case of using the photosensitive resin composition of the comparative example. . Moreover, the binder polymer which has the structural unit derived from (meth) acrylic acid, a photopolymerizable compound, and a photoinitiator, the weight average molecular weight of a binder polymer is 20000 or more, dispersion | distribution of a binder polymer It was found that by using a photosensitive resin composition having a degree of 1.4 or less, a resist pattern having excellent resolution can be formed compared to the case of using the photosensitive resin composition of the comparative example.

  DESCRIPTION OF SYMBOLS 1 ... Photosensitive element, 2 ... Support body, 3 ... Photosensitive resin composition layer, 4 ... Protective layer, 10 ... Conductive layer, 15 ... Insulating layer, 20 ... Mask, 30 ... Resist pattern, 32 ... Photosensitive resin composition Physical layer, 40 ... circuit pattern, 42 ... plating layer.

Claims (6)

Containing a structural unit derived from (meth) acrylic acid, and a binder polymer having a structural unit derived from styrene or α-methylstyrene, a photopolymerizable compound, and a photopolymerization initiator,
The binder polymer has a weight average molecular weight of 20000 or more,
A photosensitive resin composition, wherein the binder polymer is a polymer obtained by reversible addition-fragmentation chain transfer polymerization. Containing a structural unit derived from (meth) acrylic acid, and a binder polymer having a structural unit derived from styrene or α-methylstyrene, a photopolymerizable compound, and a photopolymerization initiator,
The content of the structural unit derived from styrene or α-methylstyrene is 45% by mass to 70% by mass based on the total mass of the polymerizable monomer constituting the binder polymer,
The binder polymer has a weight average molecular weight of 20000 or more,
The photosensitive resin composition whose dispersion degree of the said binder polymer is 1.4 or less.   A photosensitive element comprising: a support; and a photosensitive resin composition layer formed on the support and formed from the photosensitive resin composition according to claim 1. A photosensitive layer forming step of forming a photosensitive resin composition layer on the substrate using the photosensitive resin composition according to claim 1 or 2,
An exposure step of irradiating at least a part of the photosensitive resin composition layer with actinic rays and photocuring the region to form a cured product region;
A step of removing a region other than the cured product region of the photosensitive resin composition layer from the substrate, and forming a resist pattern which is the cured product region on the substrate, to form a resist pattern Method.   The method for forming a resist pattern according to claim 4, wherein the wavelength of the active light is in a range of 340 nm to 430 nm.   A method for manufacturing a printed wiring board, comprising a step of etching or plating a substrate on which a resist pattern is formed by the method for forming a resist pattern according to claim 4.

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