Photosensitive resin composition, cured film, and semiconductor device

Abstract

The present invention provides: a photosensitive resin composition which exhibits excellent brittle fracture resistance and can produce a cured film having high patterning precision; a cured film having high reliability and patterning precision; and a semiconductor device containing said cured film. This photosensitive resin composition can be used to produce a cured film of a semiconductor device, and contains a phenolic resin (A), a crosslinking agent (B) and an acid generator (C). The crosslinking agent (B) includes a first component that is a solid at normal temperature and a second component that is a liquid at normal temperature. The cured product has a tensile elongation of 25% or more. When the cured product is used to form a trench pattern having a trench width of 10 µm and a film thickness of 5 µm, the tapering angle at an end surface that faces the trench is 50° or more in a cross section of the trench pattern.

Description

Photosensitive resin composition, cured film, and semiconductor device

[0001] The present invention relates to a photosensitive resin composition, a cured film, and a semiconductor device.

[0002] The rewiring layer of the semiconductor device includes an insulating layer and a wiring layer. Of these, the insulating layer is formed using a photosensitive resin composition and is patterned into a desired shape.

[0003] For example, Patent Document 1 discloses a photosensitive resin composition containing an alkaline aqueous solution-soluble resin, a crosslinking agent, a photopolymerization initiator, and an epoxy resin (thermosetting resin). It also discloses that the use of this photosensitive resin composition produces a cured product that is excellent in flexibility, adhesion, pencil hardness, solvent resistance, acid resistance, heat resistance, gold plating resistance, etc. It also discloses that the cured product can be used as an interlayer insulating material for electronic components.

[0004] JP 2016-80871 A

[0005] As electronic devices become more sophisticated, there is a demand for higher reliability and higher density in redistribution layers. To achieve higher reliability, it is necessary to suppress brittle fracture caused by temperature changes. To achieve higher density, it is also necessary to improve the wiring density in the redistribution layers.

[0006] An object of the present invention is to provide a photosensitive resin composition capable of producing a cured film that has excellent resistance to brittle fracture and high patterning precision, a cured film that has high reliability and high patterning precision, and a semiconductor device that includes such a cured film.

[0007] These objects are achieved by the present invention as set forth in the following (1) to (11): (1) A photosensitive resin composition used in the production of a cured film for a semiconductor device, comprising: a phenolic resin (A), a crosslinking agent (B), and an acid generator (C), wherein the crosslinking agent (B) comprises a first component that is solid at room temperature and a second component that is liquid at room temperature, the photosensitive resin composition having a tensile elongation of 25% or more after curing, and when used to form a trench pattern having a trench width of 10 μm and a film thickness of 5 μm, the photosensitive resin composition has a taper angle of 50° or more at an end face facing the trench in a cross section of the trench pattern.

[0008] (2) The photosensitive resin composition according to (1) above, wherein the first component contains a urea compound and an epoxy compound.

[0009] (3) The photosensitive resin composition according to (2) above, wherein the epoxy compound contained in the first component contains an aromatic ring.

[0010] (4) The photosensitive resin composition according to (2) or (3) above, wherein the number of functional groups of the epoxy compound contained in the first component is 3 or more.

[0011] (5) The photosensitive resin composition according to (1) above, wherein the second component contains a difunctional phenoxy-type epoxy resin.

[0012] (6) The photosensitive resin composition according to any one of (1) to (5) above, wherein the average number of functional groups per molecule of the crosslinking agent (B) is 2.4 or more and 3.6 or less.

[0013] (7) The photosensitive resin composition according to any one of (1) to (6) above, wherein the content of the first component is greater than the content of the second component in terms of mass ratio.

[0014] (8) The photosensitive resin composition according to any one of (1) to (7), wherein the glass transition temperature of the cured product is 230° C. or higher and 300° C. or lower.

[0015] (9) The photosensitive resin composition according to any one of (1) to (8) above, wherein the 5% weight loss temperature of the cured product is 300° C. or higher and 400° C. or lower.

[0016] (10) A cured film comprising a cured product of the photosensitive resin composition according to any one of (1) to (9) above.

[0017] (11) A semiconductor device comprising: a semiconductor element; and the cured film according to (10) above, provided on a surface of the semiconductor element.

[0018] According to the present invention, a photosensitive resin composition is obtained which has excellent resistance to brittle fracture and can be used to produce a cured film with high patterning accuracy.

[0019] Furthermore, according to the present invention, a cured film having high reliability and patterning accuracy can be obtained. Furthermore, according to the present invention, a semiconductor device including the above cured film can be obtained.

[0020] Fig. 1 is a cross-sectional view showing an example of a trench pattern formed using a photosensitive resin composition, and Fig. 2 is a cross-sectional view showing a semiconductor device including a cured film according to an embodiment (a semiconductor device according to an embodiment).

[0021] DETAILED DESCRIPTION OF THE INVENTION The photosensitive resin composition, cured film, and semiconductor device according to the present invention will be described in detail below with reference to preferred embodiments shown in the accompanying drawings.

[0022] 1. Photosensitive Resin Composition The photosensitive resin composition according to this embodiment is a resin material used to form a cured film (cured film) of a semiconductor device. This photosensitive resin composition contains a phenolic resin (A), a crosslinking agent (B), and an acid generator (C). The crosslinking agent (B) contains a first component (B1) that is solid at room temperature and a second component (B2) that is liquid at room temperature. Furthermore, this photosensitive resin composition has a tensile elongation of 25% or more when cured. Furthermore, after using this photosensitive resin composition to form a trench pattern with a trench width of 10 μm and a film thickness of 5 μm, when the cross section of the trench pattern is observed, the taper angle of the end face facing the trench is 50° or more.

[0023] This configuration allows for the realization of a photosensitive resin composition that can produce a cured film that has excellent resistance to brittle fracture and high patterning accuracy. The cured film produced using this composition can be used in semiconductor devices, contributing to the realization of, for example, a redistribution layer with high definition and reliability. This allows for improved wiring density in the redistribution layer and improved resistance to temperature cycle tests, etc.

[0024] 1.1. Phenolic Resin (A) Examples of the phenolic resin (A) include phenol novolac resins, naphthalene ring-containing phenolic resins, aralkyl phenolic resins, triphenolalkane phenolic resins, biphenyl phenolic resins, alicyclic phenolic resins, heterocyclic phenolic resins, naphthalene ring-containing phenolic resins, and bisphenol phenolic resins, and one or a mixture of two or more of these may be used.

[0025] Among these, biphenyl-type phenolic resin (A1) is preferably used as the phenolic resin (A). The biphenyl-type phenolic resin (A1) is a phenolic resin having a biphenyl structure. As the biphenyl-type phenolic resin, a phenolic resin having a structural unit represented by the following formula (1) is preferably used. This can improve the low-temperature curability of the photosensitive resin composition and the reliability of the cured film. Furthermore, with the improvement in low-temperature curability, the taper angle of the end face of the trench pattern can be increased. This allows for higher definition of the trench pattern, and for example, enables an improvement in the wiring density of the rewiring layer.

[0026]

[0027] In the above formula (1), R ４１ and R ４２are each independently a monovalent substituent selected from the group consisting of a hydroxyl group, a halogen atom, a carboxyl group, a saturated or unsaturated alkyl group having 1 to 20 carbon atoms, an alkyl ether group having 1 to 20 carbon atoms, a saturated or unsaturated alicyclic group having 3 to 20 carbon atoms, or an organic group having an aromatic structure having 6 to 20 carbon atoms, and these may be bonded via an ester bond, an ether bond, an amide bond, or a carbonyl bond. Furthermore, r and s are each independently an integer of 0 to 3. Furthermore, Y ４ and Z ４ are each independently selected from the group consisting of an aliphatic group having 1 to 10 carbon atoms, which may have a single bond or an unsaturated bond, an alicyclic group having 3 to 20 carbon atoms, and an organic group having an aromatic structure having 6 to 20 carbon atoms. ４ is bonded to one of the two benzene rings.

[0028] In addition, in the structural unit represented by the above formula (1), a hydroxyl group is bonded to the biphenyl structure. Although the detailed mechanism of action is unknown, it is thought that this hydroxyl group contributes to increasing the taper angle of the end face of the trench pattern.

[0029] The biphenyl-type phenol resin (A1) having the structural unit represented by the above formula (1) can be obtained, for example, using the method described in JP-A-2018-155938.

[0030] The weight-average molecular weight of the biphenyl-type phenolic resin (A1) is preferably 12,000 or more, more preferably 15,000 or more, and even more preferably 20,000 or more. This improves the curability of the photosensitive resin composition and increases the elongation of the cured film. The weight-average molecular weight of the biphenyl-type phenolic resin (A1) is preferably 500,000 or less, more preferably 400,000 or less, and even more preferably 200,000 or less. This ensures appropriate solubility of the photosensitive resin composition in solvents.

[0031] The content of the biphenyl-type phenolic resin (A1) in the photosensitive resin composition is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, of the total solid content of the photosensitive resin composition. This can improve the curability of the photosensitive resin composition. Furthermore, the content of the biphenyl-type phenolic resin (A1) in the photosensitive resin composition is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less, of the total solid content of the photosensitive resin composition. This can suppress a decrease in the elongation of the cured film.

[0032] Furthermore, from the viewpoint of obtaining a photosensitive resin composition having excellent low-temperature curing properties, it is preferable that the biphenyl-type phenolic resin (A2) contains a resin having a structure represented by the following formula (2). By containing such a biphenyl-type phenolic resin (A2), the curability of the photosensitive resin composition and the elongation of the cured film can be further improved. Furthermore, along with the improved low-temperature curing properties, the taper angle of the end faces of the trench pattern can be further increased.

[0033]

[0034] In the above formula (2), n is preferably 6 or more, more preferably 10 or more, and even more preferably 14 or more. This can further improve the curability of the photosensitive resin composition and the elongation of the cured film. In addition, the improved curability at low temperatures can further increase the taper angle of the end faces of the trench pattern.

[0035] From the viewpoint of solvent solubility, n is preferably 72 or less, more preferably 54 or less, and even more preferably 36 or less.

[0036] The weight-average molecular weight of the biphenyl-type phenolic resin (A2) is preferably 500 or more, more preferably 2,000 or more, and even more preferably 4,000 or more. This can improve curability and elongation of the cured film. Furthermore, the weight-average molecular weight of the biphenyl-type phenolic resin (A2) is preferably 50,000 or less, more preferably 20,000 or less, and even more preferably 10,000 or less. This can ensure appropriate solubility in solvents.

[0037] When the photosensitive resin composition contains a biphenyl-type phenolic resin (A2), the content of the biphenyl-type phenolic resin (A2) is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, of the total solid content of the photosensitive resin composition. This ensures good curability. Furthermore, the content of the biphenyl-type phenolic resin (A2) in the photosensitive resin composition is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less, of the total solid content of the photosensitive resin composition. This prevents a decrease in the elongation of the cured film.

[0038] The photosensitive resin composition may contain the biphenyl-type phenolic resin (A1) and the biphenyl-type phenolic resin (A2) in combination. In this case, the total content of the biphenyl-type phenolic resin (A1) and the biphenyl-type phenolic resin (A2) is preferably 30% by mass or more, more preferably 45% by mass or more, and even more preferably 55% by mass or more, of the total solid content of the photosensitive resin composition, from the viewpoints of improving curability at low temperatures, the reliability of the cured film, and the taper angle of the end faces of the trench pattern. Furthermore, the total content of the biphenyl-type phenolic resin (A1) and the biphenyl-type phenolic resin (A2) in the photosensitive resin composition is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less, of the total solid content of the photosensitive resin composition, from the viewpoints of improving photosensitivity and the chemical resistance of the cured film.

[0039] The photosensitive resin composition may contain a thermosetting resin other than the biphenyl-type phenolic resin (A1) and the biphenyl-type phenolic resin (A2). Examples of such a thermosetting resin include a hydroxystyrene resin, a polyamide resin, a polybenzoxazole resin, a polyimide resin, and a cyclic olefin resin.

[0040] 1.2. Crosslinking Agent (B) The crosslinking agent (B) contains a first component (B1) that is solid at room temperature and a second component (B2) that is liquid at room temperature. By including the first component (B1) and the second component (B2) in the crosslinking agent (B), it is possible to achieve both deformation resistance and crosslinkability in the photosensitive coating formed using the photosensitive resin composition. This allows for the realization of a photosensitive resin composition that can produce a cured film with a sufficiently large tensile elongation of the cured product and a sufficiently large taper angle of the end face when a trench pattern is formed. Therefore, the use of such a photosensitive resin composition makes it possible to produce a cured film that has excellent resistance to brittle fracture and high patterning accuracy. Note that, in this specification, "room temperature" refers to 23°C.

[0041] The first component (B1) mainly suppresses the fluidity of the photosensitive coating formed using the photosensitive resin composition, thereby contributing to improving the deformation resistance. By improving the deformation resistance of the photosensitive coating, for example, when the photosensitive coating is patterned into a shape including a trench pattern, deformation of the photosensitive coating can be suppressed, thereby realizing a photosensitive resin composition that can produce a cured film with a sufficiently large taper angle at the end face facing the trench.

[0042] The first component (B1) may be any component that functions as a crosslinking agent and is solid at room temperature, and examples thereof include urea compounds, epoxy compounds, melamine compounds, cyano compounds, isocyanate compounds, maleimide compounds, benzoguanamine compounds, metal chelating agents, etc. The first component (B1) may also be a mixture of two or more compounds.

[0043] Of these, the first component (B1) preferably contains a urea compound or an epoxy compound, which can particularly enhance the deformation resistance of the photosensitive coating.

[0044] The second component (B2) mainly contributes to improving the crosslinkability of the photosensitive coating formed using the photosensitive resin composition. By improving the crosslinkability of the photosensitive coating, crosslinking in the photosensitive coating is promoted, for example, when the photosensitive coating is patterned into a shape including a trench pattern. This makes it easier to maintain the shape immediately after patterning. As a result, a photosensitive resin composition can be realized that can produce a cured film with a sufficiently large taper angle on the end face facing the trench. Furthermore, the improved crosslinkability can contribute to improving the tensile elongation of the cured film. Furthermore, a photosensitive resin composition can be realized that can produce a cured film with excellent mechanical properties, even when subjected to low-temperature curing, for example, at around 200°C.

[0045] The second component (B2) may be any component that functions as a crosslinking agent and is liquid at room temperature, and examples thereof include urea compounds, epoxy compounds, melamine compounds, cyano compounds, isocyanate compounds, maleimide compounds, benzoguanamine compounds, metal chelating agents, etc. The second component (B2) may also be a mixture of two or more compounds.

[0046] Of these, the second component (B2) preferably contains a urea compound or an epoxy compound, and more preferably contains both of these, which can particularly enhance the crosslinking properties of the photosensitive coating.

[0047] 1.2.1 Urea Compounds The urea compounds used as the crosslinking agent (B) are urea compounds having, on average, two or more functional groups per molecule that contribute to crosslinking. The urea compounds are compounds that contain a urea structure (—NC(═O)N—). Examples of the functional group include a methylol group and an alkoxyalkyl group.

[0048] Specific examples of the urea compound include bifunctional urea compounds having two functional groups on average, and polyfunctional urea compounds having three or more functional groups on average.

[0049] Examples of bifunctional urea compounds include glycoluril-based compounds such as dihydroxymethylated glycoluril, dimethoxymethylated glycoluril, diethoxymethylated glycoluril, dipropoxymethylated glycoluril, and dibutoxymethylated glycoluril; urea-based compounds such as bismethoxymethylurea, bisethoxymethylurea, bispropoxymethylurea, and bisbutoxymethylurea; dihydroxymethylated ethyleneurea, dimethoxymethylated ethyleneurea, diethoxymethylated ethyleneurea, and dipropoxymethylated glycoluril; Examples of the methylated propylene urea include ethylene urea compounds such as dimethylated ethylene urea and dibutoxymethylated ethylene urea; propylene urea compounds such as dihydroxymethylated propylene urea, dimethoxymethylated propylene urea, diethoxymethylated propylene urea, dipropoxymethylated propylene urea and dibutoxymethylated propylene urea; and imidazolidinone compounds such as 1,3-di(methoxymethyl)-4,5-dihydroxy-2-imidazolidinone and 1,3-di(methoxymethyl)-4,5-dimethoxy-2-imidazolidinone.

[0050] Examples of polyfunctional urea compounds include trifunctional urea compounds such as trihydroxymethylated glycoluril, trimethoxymethylated glycoluril, triethoxymethylated glycoluril, tripropoxymethylated glycoluril, and tributoxymethylated glycoluril, and tetrafunctional urea compounds such as tetrahydroxymethylated glycoluril, tetramethoxymethylated glycoluril, tetraethoxymethylated glycoluril, tetrapropoxymethylated glycoluril, and tetrabutoxymethylated glycoluril.

[0051] The urea compound contained in the first component (B1) is preferably a polyfunctional urea compound, and more preferably a tetrafunctional urea compound. Polyfunctional urea compounds have a relatively large number of crosslinking points. Therefore, a cured product with good mechanical properties can be produced. As a result, a cured film with good resistance to brittle fracture due to temperature changes can be obtained.

[0052] The urea compound contained in the second component (B2) is preferably a bifunctional urea compound. Bifunctional urea compounds have a relatively small number of crosslinking points. This allows the production of a photosensitive resin composition that can produce a cured film with high elongation.

[0053] The crosslinking agent (B) may contain both a bifunctional urea compound and a polyfunctional urea compound, thereby realizing a photosensitive resin composition capable of producing a cured film that has both excellent resistance to, for example, a temperature cycle test and high elongation.

[0054] 1.2.2. Epoxy Compound The epoxy compound used as the crosslinking agent (B) is an epoxy compound (epoxy resin) having, on average, two or more epoxy groups that contribute to crosslinking per molecule.

[0055] Specific examples of epoxy compounds include bifunctional epoxy compounds having two epoxy groups on average, and polyfunctional epoxy compounds having three or more epoxy groups on average.

[0056] The difunctional epoxy compound is not particularly limited as long as it is a difunctional epoxy compound, but it is preferable to use a difunctional phenoxy epoxy resin. This tends to lengthen the molecular chain, imparting high flexibility to the cured film. As a result, a cured film with particularly high elongation can be obtained. In addition, since it contains an aromatic ring, the mechanical properties (such as breaking strength) of the cured film can be improved.

[0057] Examples of bifunctional phenoxy type epoxy resins include bisphenol A type phenoxy resins, bisphenol F type phenoxy resins, bisphenol S type phenoxy resins, bisphenol acetophenone type phenoxy resins, novolac type phenoxy resins, biphenyl type phenoxy resins, fluorene type phenoxy resins, dicyclopentadiene type phenoxy resins, norbornene type phenoxy resins, naphthalene type phenoxy resins, anthracene type phenoxy resins, adamantane type phenoxy resins, terpene type phenoxy resins, and trimethylcyclohexane type phenoxy resins.

[0058] Specific examples of the difunctional epoxy compound include EXA-4850-150, EXA-4816, and EXA-4822 manufactured by DIC Corporation; EP-4000S, EP-4000SS, EP-4003S, EP-4010S, and EP-4011S manufactured by ADEKA Corporation; BEO-60E and BPO-20E manufactured by New Japan Chemical Co., Ltd.; YX-7105, YX-7110, YX-7400, and YX-7180 ​​manufactured by Mitsubishi Chemical Corporation; and LX-01 manufactured by Osaka Soda Co., Ltd.

[0059] The polyfunctional epoxy compound is not particularly limited as long as it is a polyfunctional epoxy compound (having three or more functional groups).

[0060] Specific examples of polyfunctional epoxy compounds include Epikote 180 and Epikote 157 manufactured by Mitsubishi Chemical Corporation; UVR-6610, UVR-6620, and UVR-6650 manufactured by Union Carbide Corporation; TACT1X742 manufactured by Dow Chemical Company; and Techmore VG3101L manufactured by Printec Co., Ltd.

[0061] The epoxy compound contained in the first component (B1) may be a multifunctional epoxy compound, with trifunctional epoxy compounds being particularly preferred. Multifunctional epoxy compounds have a relatively large number of crosslinking points. This allows for the production of cured products with good mechanical properties. Furthermore, trifunctional epoxy compounds in particular have both a large number of crosslinking points and molecular chain flexibility. This allows for the production of cured films that have a good balance between good mechanical properties and high elongation. As a result, cured films with particularly good resistance to brittle fracture due to temperature changes and the like are obtained.

[0062] The epoxy compound contained in the second component (B2) is preferably a difunctional epoxy compound. Difunctional epoxy compounds have a relatively small number of crosslinking points. This allows the production of a photosensitive resin composition that can produce a cured film with high elongation.

[0063] The crosslinking agent (B) may contain both a difunctional epoxy compound and a polyfunctional epoxy compound. This results in a cured film having both a flexible structure derived from the difunctional epoxy compound and a rigid structure derived from the polyfunctional epoxy compound. As a result, even when subjected to a temperature cycle test, a cured film is obtained that exhibits excellent mechanical properties (breaking strength) and high elongation. Flexible structures include structures dominated by aliphatic hydrocarbons, such as alkylene groups having 1 to 8 carbon atoms, ethylene glycol groups, propylene glycol groups, and butylene glycol groups. Rigid structures include structures dominated by aromatic rings, such as fused aromatic ring structures (e.g., benzene rings, naphthalene rings, anthracene rings, and pyrene rings), aromatic ring structures (e.g., biphenyl rings, cardo structures, and fluorene rings), and heterocyclic structures (e.g., pyrrole rings and thiophene rings).

[0064] In view of the above, the epoxy compound contained in the first component (B1) preferably contains an aromatic ring. With this configuration, a rigid structure with stable properties derived from the aromatic ring is formed in the cured film, and a flexible structure is easily formed between the aromatic ring and the epoxy group. This allows for the production of a cured film that has both good mechanical properties and high elongation.

[0065] 1.2.3. Amount of Blend The content of the first component (B1) is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 25 parts by mass or more, per 100 parts by mass of the phenolic resin (A). This sufficiently enhances the deformation resistance of the photosensitive coating, allowing for the production of a cured film with a sufficiently large taper angle at the end face. Furthermore, the content of the first component (B1) is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less, per 100 parts by mass of the phenolic resin (A). This prevents a decrease in the shape conformability of the photosensitive coating.

[0066] The content of the second component (B2) is preferably 3 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, based on 100 parts by mass of the phenolic resin (A). This sufficiently enhances the crosslinking ability of the photosensitive coating, allowing the production of a cured film with a sufficiently large taper angle at the end face. Furthermore, the content of the second component (B2) is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less, based on 100 parts by mass of the phenolic resin (A). This prevents a decrease in the patterning accuracy of the photosensitive coating.

[0067] The content of the first component (B1) may be equal to or less than the content of the second component (B2), but is preferably set to be greater than the content of the second component (B2). In other words, the ratio of the content of the first component (B1) to the content of the second component (B2) (compounding ratio B1 / B2) is preferably greater than 1.0 by mass. Furthermore, the compounding ratio B1 / B2 is more preferably 1.5 or more and 8.0 or less, and even more preferably 2.0 or more and 4.0 or less. When the compounding ratio B1 / B2 is within the above range, the balance between the contents of the first component (B1) and the second component (B2) is optimized. This allows the photosensitive coating to have a good balance between deformation resistance and crosslinkability. As a result, a cured film can be produced that has a sufficiently high tensile elongation of the cured product and a sufficiently large taper angle of the end face when a trench pattern is formed.

[0068] The total content of the urea compound and the epoxy compound in the photosensitive resin composition is preferably 30 to 90 parts by mass, more preferably 40 to 80 parts by mass, and even more preferably 50 to 70 parts by mass, relative to 100 parts by mass of the phenolic resin (A). This more reliably achieves the effect of achieving a good balance between the deformation resistance and crosslinkability of the photosensitive coating.

[0069] The blending ratio of the urea compound to the epoxy compound in the first component (B1) is not particularly limited, but the mass ratio of the urea compound to the epoxy compound is preferably 1.0 or more, more preferably 1.5 or more and 6.0 or less, and even more preferably 2.0 or more and 5.0 or less, thereby optimizing the balance of the compounds in the first component (B1) and enabling the production of a cured film with a particularly large taper angle at the end face when a trench pattern is formed.

[0070] The average number of functional groups per molecule of the crosslinking agent (B) is preferably 2.4 to 3.6, more preferably 2.8 to 3.5, and even more preferably 3.0 to 3.4. This allows the cured product of the photosensitive resin composition to have both high elongation, high strength at break, and high glass transition temperature.

[0071] If the average number of functional groups is below the lower limit, the cured product may have reduced mechanical strength such as strength at break or reduced heat resistance depending on the glass transition temperature, whereas if the average number of functional groups is above the upper limit, the cured product may have reduced elongation.

[0072] The average number of functional groups per molecule can be calculated based on the number of functional groups of each component contained in the crosslinking agent (B) and the blending ratio of each component. For example, when a bifunctional compound and a tetrafunctional compound are blended in equal amounts, the average number of functional groups is 3.

[0073] 1.3. Acid Generator (C) The acid generator (C) generates an acid by absorbing thermal energy or light energy. By including an acid generator, a photosensitive resin composition capable of stably forming a cured product can be obtained. Examples of this acid generator include a thermal acid generator (c1) that generates an acid by thermal energy and a photoacid generator (c2) that generates an acid by light energy, and one or both of these can be used.

[0074] As the thermal acid generator (c1), a sulfonium compound or a salt thereof is preferably used.

[0075] The sulfonium compound or its salt is specifically a sulfonium salt having a sulfonium ion as the cation moiety. The anion moiety of the sulfonium compound or its salt is specifically a boride ion, an antimony ion, a phosphorus ion, or a sulfonate ion such as a trifluoromethanesulfonate ion. From the viewpoint of improving the reaction rate at low temperatures, the anion is preferably a boride ion or an antimony ion, and more preferably a boride ion. These anions may have a substituent.

[0076] The sulfonium compound or salt thereof preferably includes a sulfonium salt represented by the following formula (4):

[0077]

[0078] In the above formula (4), R １ is a hydrogen atom or a monovalent organic group, preferably a hydrogen atom or an acyl group, more preferably an acyl group, and even more preferably CH ３ It is a C(=O)- group.

[0079] R ２ represents a monovalent organic group, preferably a linear or branched hydrocarbon group or a benzyl group which may have a substituent, more preferably a benzyl group which may be substituted with an alkyl group having from 1 to 4 carbon atoms or an alkyl group having from 1 to 4 carbon atoms, and even more preferably a methyl group or a benzyl group whose aromatic ring portion may be substituted with a methyl group.

[0080] R ３ is a monovalent organic group, and from the viewpoint of improving reactivity at low temperatures, is preferably a linear or branched hydrocarbon group, more preferably an alkyl group having 1 to 4 carbon atoms, and even more preferably a methyl group.

[0081] Examples of the thermal acid generator (c1) include triphenylsulfonium salts such as triphenylsulfonium trifluoromethanesulfonate.

[0082] Examples of the photoacid generator (c2) include naphthoquinone diazide compounds, diaryl sulfonium salts, triaryl sulfonium salts, dialkylphenacylsulfonium salts, diaryliodonium salts, aryl diazonium salts, aromatic tetracarboxylic acid esters, aromatic sulfonate esters, nitrobenzyl esters, aromatic N-oxyimidosulfonates, aromatic sulfamides, benzoquinone diazosulfonate esters, etc. Among these, naphthoquinone diazide compounds are preferably used.

[0083] Examples of naphthoquinone diazide compounds that can be used include naphthoquinone diazide adducts of tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene and naphthoquinone diazide adducts of tetrahydroxybenzophenone. Here, naphthoquinone diazide adducts can be produced, for example, by reacting o-quinone diazide sulfonyl chlorides with a hydroxy compound or an amino compound.

[0084] Depending on the photoacid generator (c2), the photosensitive resin composition can be made positive or negative. Specifically, when a photoacid generator (c2) that generates acid in the exposed portion is used, the solubility of the exposed portion in a developer such as an alkaline aqueous solution increases. As a result, a positive-type photosensitive resin composition is obtained. On the other hand, when a photoacid generator (c2) that becomes insolubilized upon exposure is used, the solubility of the exposed portion in a developer decreases. As a result, a negative-type photosensitive resin composition is obtained.

[0085] From the viewpoint of improving curability, the content of the acid generator (C) in the photosensitive resin composition is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, per 100 parts by mass of the phenolic resin (A). Also, from the viewpoint of suppressing a decrease in reliability, the content of the acid generator (C) in the photosensitive resin composition is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less, per 100 parts by mass of the phenolic resin (A).

[0086] The acid generator (C) is preferably composed of both a thermal acid generator (c1) and a photoacid generator (c2). This can increase the mechanical strength of the cured product of the photosensitive resin composition. When the acid generator (C) is composed of both a thermal acid generator (c1) and a photoacid generator (c2), the total content of these is the content of the acid generator (C).

[0087] The ratio of the content of the photoacid generator (c2) to the content of the thermal acid generator (c1) (compounding ratio c2 / c1) is preferably 1 / 9 or more and 9 / 1 or less, more preferably 5 / 5 or more and 9 / 1 or less, by mass ratio, which allows for increased elongation without impairing the mechanical strength of the cured product.

[0088] 1.4. Adhesion Aid (D) The photosensitive resin composition preferably contains an adhesion aid (D), which can further enhance the adhesion between the cured product of the photosensitive resin composition and the substrate.

[0089] Examples of the adhesion aid (D) include silane coupling agents such as amino group-containing silane coupling agents, epoxy group-containing silane coupling agents, (meth)acryloyl group-containing silane coupling agents, mercapto group-containing silane coupling agents, vinyl group-containing silane coupling agents, ureido group-containing silane coupling agents, sulfide group-containing silane coupling agents, and acid anhydride-containing silane coupling agents, as well as titanium coupling agents and zirconium coupling agents. When using these coupling agents, one type may be used alone, or two or more types may be used in combination.

[0090] Examples of amino group-containing silane coupling agents include bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropylmethyldimethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltriethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldiethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane.

[0091] Examples of epoxy group-containing silane coupling agents include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and γ-glycidylpropyltrimethoxysilane.

[0092] Examples of the (meth)acryloyl group-containing silane coupling agent include γ-((meth)acryloyloxypropyl)trimethoxysilane, γ-((meth)acryloyloxypropyl)methyldimethoxysilane, and γ-((meth)acryloyloxypropyl)methyldiethoxysilane.

[0093] An example of the mercapto group-containing silane coupling agent is 3-mercaptopropyltrimethoxysilane.

[0094] Examples of vinyl group-containing silane coupling agents include vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, and vinyltrimethoxysilane.

[0095] Examples of ureido group-containing silane coupling agents include 3-ureidopropyltriethoxysilane.

[0096] Examples of sulfide group-containing silane coupling agents include bis(3-(triethoxysilyl)propyl)disulfide and bis(3-(triethoxysilyl)propyl)tetrasulfide.

[0097] Examples of the acid anhydride-containing silane coupling agent include 3-trimethoxysilylpropylsuccinic anhydride, 3-triethoxysilylpropylsuccinic anhydride, and 3-dimethylmethoxysilylpropylsuccinic anhydride.

[0098] The adhesion aid (D) may contain an adhesion aid other than those mentioned above.

[0099] The content of the adhesion aid (D) in the photosensitive resin composition is preferably 0.3 parts by mass or more and 15 parts by mass or less, more preferably 0.4 parts by mass or more and 12 parts by mass or less, and even more preferably 0.5 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the phenolic resin (A).

[0100] 1.5. Surfactant (E) The photosensitive resin composition may contain a surfactant (E). By including the surfactant (E), wettability during coating can be improved, and a uniform coated film and cured film can be obtained. Examples of the surfactant (E) include fluorine-based surfactants, silicone-based surfactants, alkyl-based surfactants, and acrylic surfactants.

[0101] The surfactant (E) preferably contains a surfactant containing at least one of a fluorine atom and a silicon atom. This contributes to obtaining a uniform coating film (improved coating properties), improving developability, and also improving adhesive strength. Such surfactants are preferably, for example, nonionic surfactants containing at least one of a fluorine atom and a silicon atom. Commercially available surfactants that can be used include, for example, the "Megafac (registered trademark)" series manufactured by DIC Corporation, including F-251, F-253, F-281, F-430, F-477, F-551, F-552, F-553, F-554, F-555, F-556, F-557, F-558, F-559, F-560, F-561, F-562, F-563, F-565, F-568, F-569, F-570, F-572, and F- Fluorine-containing oligomer surfactants such as F-574, F-575, F-576, R-40, R-40-LM, R-41, and R-94, fluorine-containing nonionic surfactants such as Ftergent 250 and Ftergent 251 manufactured by Neos Corporation, and silicone surfactants such as the SILFOAM (registered trademark) series manufactured by Wacker Chemie (e.g., SD100TS, SD670, SD850, SD860, and SD882). The photosensitive resin composition may contain a mixture of two or more of these surfactants.

[0102] The content of the surfactant (E) in the photosensitive resin composition is preferably 0.001 parts by mass or more and 1 part by mass or less, and more preferably 0.005 parts by mass or more and 0.5 parts by mass or less, relative to 100 parts by mass of the phenolic resin (A).

[0103] 1.6 Solvent The photosensitive resin composition preferably contains a solvent, which allows the photosensitive resin composition to be in the form of a varnish.

[0104] The solvent is, for example, an organic solvent. The organic solvent is not particularly limited as long as it can dissolve or disperse the above-mentioned components and does not substantially chemically react with each component.

[0105] Examples of organic solvents include acetone, methyl ethyl ketone, toluene, propylene glycol methyl ethyl ether, propylene glycol dimethyl ether, propylene glycol 1-monomethyl ether 2-acetate, diethylene glycol ethyl methyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, benzyl alcohol, propylene carbonate, ethylene glycol diacetate, propylene glycol diacetate, propylene glycol monomethyl ether acetate, dipropylene glycol methyl-n-propyl ether, butyl acetate, γ-butyrolactone, etc. These may be used alone or in combination.

[0106] When a solvent is used, it is used so that the concentration of nonvolatile components in the photosensitive resin composition is preferably 30 to 75% by mass, more preferably 35 to 70% by mass. By using a solvent in this range, each component can be sufficiently dissolved or dispersed. Furthermore, good coatability can be ensured, leading to improved flatness during spin coating, for example. Furthermore, adjusting the content of nonvolatile components allows the viscosity of the photosensitive resin composition to be appropriately controlled.

[0107] 1.7 Other Components In addition to the components described above, the photosensitive resin composition may contain other components as needed. Examples of other components include antioxidants, fillers such as silica, sensitizers, and film-forming agents.

[0108] 1.8. Physical Properties of Photosensitive Resin Composition Next, the physical properties of the photosensitive resin composition according to this embodiment will be described.

[0109] 1.8.1. Tensile Elongation The photosensitive resin composition has a tensile elongation of 25% or more when cured. It is also preferably 35% or more, and more preferably 45% or more. Having such a tensile elongation can enhance the resistance of the cured film to brittle fracture. When the cured film is used in a semiconductor device, the resistance of the semiconductor device to temperature cycle testing can be enhanced, resulting in a highly reliable semiconductor device. From the viewpoint of obtaining a cured film more stably, the tensile elongation of the cured film is preferably 90% or less, and more preferably 70% or less.

[0110] The tensile elongation of the cured product is determined by the following method. First, a photosensitive resin composition is applied to the upper surface of a silicon wafer using a spin coater. The thickness of the applied film is set so that the film thickness after drying is 10 μm. Next, the obtained applied film is pre-baked on a hot plate at 100° C. for 4 minutes to obtain a photosensitive coating. Next, the obtained photosensitive coating is exposed to a high-pressure mercury lamp at an exposure dose of 600 mJ / cm. ２ Next, the silicon wafer with the photosensitive coating is placed in a clean oven and post-baked under a nitrogen atmosphere at 220°C for 240 minutes, thereby curing the photosensitive coating and obtaining a cured film.

[0111] Next, a 6.5 mm x 60 mm sample is cut out from the obtained cured film. Next, a tensile test is performed on the sample, and the tensile elongation is calculated from the break distance and the initial distance. The tensile test is performed according to a method in accordance with JIS K 7161:2014, and the test conditions are 23°C and an extension rate of 5 mm / min. For example, a tensile tester such as Orientec Co., Ltd.'s Tensilon RTC-1210A tensile tester is used. Then, the test is performed on five samples, and the average of the calculated tensile elongations is used as the tensile elongation of the cured product.

[0112] 1.8.2. Taper Angle of End Faces FIG. 1 is a cross-sectional view showing an example of a trench pattern 22 formed using a photosensitive resin composition.

[0113] The specimen 2 shown in FIG. 1 includes a silicon wafer 21 and a trench pattern 22 formed on an upper surface 212 of the silicon wafer 21. The trench pattern 22 includes a 5 μm-thick cured film 24 and a 10 μm-wide trench 26 formed in a portion of the cured film 24. The angle between the upper surface 212 of the silicon wafer 21 and an end surface 252 of the cured film 24 facing the trench 26 is defined as the taper angle θ of the end surface 252. The taper angle θ of the end surface 252 in the trench pattern 22 formed using a photosensitive resin composition is 50° or greater. Furthermore, the taper angle θ is preferably 55° or greater, and more preferably 60° or greater. By satisfying this taper angle θ range, the photosensitive coating formed using the photosensitive resin composition exhibits high patterning accuracy. Therefore, by using such a photosensitive coating, it is possible to easily manufacture, for example, a rewiring layer with a high wiring density.

[0114] On the other hand, the upper limit of the taper angle θ is 90° or less, preferably 80° or less, and more preferably 75° or less. This allows the trench pattern 22 to be stably formed. Therefore, for example, a redistribution layer with a high wiring density can be stably manufactured.

[0115] The method for forming the specimen 2 is as follows. First, a photosensitive resin composition is applied to the upper surface 212 of the silicon wafer 21 using a spin coater. The thickness of the applied film is set so that the film will be 5 μm thick after curing. Next, the obtained applied film is pre-baked on a hot plate at 100° C. for 4 minutes to obtain a photosensitive coating. Next, the obtained photosensitive coating is exposed to a predetermined exposure amount using a stepper equipped with a mask. The mask has a pattern set so that trenches 26 with a width of 10 μm after curing are formed. When the photosensitive resin composition is a positive type, light including i-rays is used, and the exposure amount is set to 1000 mJ / cm. ２ When the photosensitive resin composition is a negative type, light including g-ray is used, and the exposure dose is 10,000 mJ / cm ２ Then, the substrate is baked on a hot plate at 100° C. for 1 minute.

[0116] Next, a 2.38% aqueous solution of tetramethylammonium hydroxide is used as the developer, and puddle development is performed twice to dissolve and remove the exposed and unexposed areas. The wafer is then rinsed with pure water for 10 seconds, and then shaken dry. This results in a silicon wafer 21 with a patterned photosensitive coating.

[0117] Next, the silicon wafer 21 having the patterned photosensitive coating is placed in a clean oven and post-baked under conditions of 230° C. and 120 minutes in a nitrogen atmosphere, thereby hardening the patterned photosensitive coating and obtaining a trench pattern 22.

[0118] The taper angle θ is measured as follows. First, the obtained trench pattern 22 is cut in the thickness direction of the silicon wafer 21 and in a direction perpendicular to the extension direction of the trenches 26. After polishing the cross section, the polished surface is observed with a scanning electron microscope. Then, the angle between the upper surface 212 and the end surface 252 in the observed image is measured, and the measured value is taken as the taper angle θ. Note that if the line of the end surface 252 is curved in the observed image, a straight line L is drawn connecting the lower end of the end surface 252 to the upper end of the end surface 252, and the angle between the upper surface 212 and the straight line L is taken as the taper angle θ.

[0119] 1.8.3. Tensile Break Strength The tensile break strength of the cured product of the photosensitive resin composition is preferably 100 MPa or more, more preferably 105 MPa or more, and even more preferably 110 MPa or more. Having such a tensile break strength can further increase the resistance of the cured film to brittle fracture. From the viewpoint of obtaining a cured film more stably, the tensile break strength of the cured product is preferably 200 MPa or less, more preferably 150 MPa or less.

[0120] The tensile breaking strength of the cured product of the photosensitive resin composition is determined by the following method. First, the photosensitive resin composition is applied to the upper surface of a silicon wafer using a spin coater. The thickness of the applied film is set so that the film thickness after drying is 10 μm. Next, the obtained applied film is pre-baked on a hot plate at 100° C. for 4 minutes to obtain a photosensitive coating. Next, the obtained photosensitive coating is exposed to an exposure dose of 600 mJ / cm using a high-pressure mercury lamp. ２ Next, the silicon wafer with the photosensitive coating is placed in a clean oven and post-baked under a nitrogen atmosphere at 220°C for 240 minutes, thereby curing the photosensitive coating and obtaining a cured film.

[0121] Next, a 6.5 mm x 60 mm sample is cut out from the obtained cured film. Next, a tensile test is performed on the sample, and the tensile elongation is calculated from the break distance and the initial distance. The tensile test is performed according to a method in accordance with JIS K 7161:2014, and the test conditions are 23°C and an extension rate of 5 mm / min. For example, a tensile tester such as Orientec Co., Ltd.'s Tensilon RTC-1210A tensile tester is used. Then, the test is performed on five samples, and the average value of the stress at break is used as the tensile breaking strength of the cured product described above.

[0122] 1.8.4. Glass Transition Temperature (Tg) The glass transition temperature (Tg) of the cured product of the photosensitive resin composition is preferably 230°C or higher, more preferably 240°C or higher. Such a glass transition temperature can enhance the deformation resistance of the cured film against temperature changes. From the viewpoint of obtaining a cured film more stably, the glass transition temperature of the cured product is preferably 300°C or lower, more preferably 280°C or lower.

[0123] The glass transition temperature of the cured product of the photosensitive resin composition can be determined by the following method. First, the photosensitive resin composition is applied to the upper surface of a silicon wafer using a spin coater. The thickness of the applied film is set so that the film thickness after drying is 10 μm. Next, the obtained applied film is pre-baked on a hot plate at 100° C. for 4 minutes to obtain a photosensitive coating. Next, the obtained photosensitive coating is exposed to an exposure dose of 600 mJ / cm using a high-pressure mercury lamp.２ The silicon wafer with the photosensitive coating is then placed in a clean oven and post-baked at 220°C for 240 minutes in a nitrogen atmosphere. This hardens the photosensitive coating, yielding a cured film. Next, an 8 mm x 40 mm sample is prepared from the resulting cured film. Next, dynamic viscoelasticity measurement is performed using a dynamic viscoelasticity measurement device (DMA device, manufactured by TA Instruments, Q800) at a heating rate of 5°C / min and a frequency of 1 Hz. The temperature at which the loss tangent tanδ determined from the measurement results is at its maximum is taken as the glass transition temperature.

[0124] 1.8.5. Coefficient of Linear Thermal Expansion (CTE) The coefficient of linear thermal expansion (CTE) of the cured product of the photosensitive resin composition is preferably 65 ppm / K or less, more preferably 60 ppm / K or less. Having such a coefficient of linear thermal expansion ensures adhesion of the cured film to a substrate or the like. From the viewpoint of obtaining a cured film more stably, the coefficient of linear thermal expansion of the cured product is preferably 20 ppm / K or more, more preferably 25 ppm / K or more.

[0125] The linear thermal expansion coefficient of the cured product of the photosensitive resin composition is determined by the following method. First, the photosensitive resin composition is applied to the upper surface of a silicon wafer using a spin coater. The thickness of the applied film is set so that the film thickness after drying is 10 μm. Next, the obtained applied film is pre-baked on a hot plate at 100° C. for 4 minutes to obtain a photosensitive coating. Next, the obtained photosensitive coating is exposed to an exposure dose of 600 mJ / cm using a high-pressure mercury lamp. ２ The silicon wafer with the photosensitive coating is then placed in a clean oven and post-baked at 220°C for 240 minutes in a nitrogen atmosphere. This hardens the photosensitive coating, yielding a cured film. A 5 mm x 13 mm sample is then prepared from the resulting cured film. Next, using a thermomechanical analyzer (TMA), tensile mode thermomechanical measurements are performed under the following conditions: starting temperature 30°C, measurement temperature range 30 to 440°C, and heating rate 10°C / min. The linear thermal expansion coefficient in the temperature range of 50 to 100°C is then determined from the measurement results.

[0126] 1.8.6.5% Weight Loss Temperature (Td5) The 5% weight loss temperature (Td5) of the cured product of the photosensitive resin composition is preferably 300°C or higher and 400°C or lower, more preferably 320°C or higher and 370°C or lower. By having such a 5% weight loss temperature, the heat resistance of the cured film can be ensured. This makes it possible to realize a cured film with good resistance to, for example, temperature cycle tests.

[0127] The 5% weight loss temperature of the cured product of the photosensitive resin composition can be determined by the following method. First, the photosensitive resin composition is applied to the upper surface of a silicon wafer using a spin coater. The thickness of the applied film is set so that the film thickness after drying is 10 μm. Next, the obtained applied film is pre-baked on a hot plate at 100° C. for 4 minutes to obtain a photosensitive coating. Next, the obtained photosensitive coating is exposed to an exposure dose of 600 mJ / cm using a high-pressure mercury lamp. ２ The silicon wafer with the photosensitive coating is then placed in a clean oven and post-baked at 220°C for 240 minutes in a nitrogen atmosphere. This hardens the photosensitive coating, yielding a cured film as a sample. The resulting sample is then subjected to simultaneous thermogravimetric and differential thermal analysis, and the temperature at which the weight has decreased by 5% from the initial value is determined as the 5% weight loss temperature. The measurement conditions are a nitrogen flow of 30 mL / min and a heating rate of 10°C / min.

[0128] 2. Cured Film Next, the cured film according to the embodiment will be described.

[0129] A cured product is obtained by curing the photosensitive resin composition according to this embodiment. The cured film according to this embodiment is composed of this cured product. Such a cured film is used as a resin film in a semiconductor device. The resin film is used, for example, as a permanent film or a resist. Among these, it is preferably used as a permanent film from the viewpoints of having high elongation, resistance to brittle fracture, and the ability to achieve high patterning precision. Examples of permanent films include protective films such as buffer coat films, interlayer films such as insulating films for rewiring, and dam materials.

[0130] 3. Semiconductor Device Next, a semiconductor device according to an embodiment will be described.

[0131] FIG. 2 is a cross-sectional view showing a semiconductor device including a cured film according to an embodiment (a semiconductor device according to an embodiment).

[0132] The semiconductor device 100 shown in FIG. 2 includes a semiconductor element (not shown), a multilayer wiring layer including an interlayer insulating film 30 and a top layer wiring 34 provided on the semiconductor element, a passivation film 32, a redistribution layer 40, a UBM layer 50, and a bump 52.

[0133] The interlayer insulating film 30 and the uppermost wiring 34 are provided at the top of the multi-layer wiring layer. The uppermost wiring 34 is made of a metal material containing, for example, aluminum or copper.

[0134] The passivation film 32 is provided on the multi-layer wiring layer, and an opening is provided in part of the passivation film 32 to expose the uppermost wiring 34.

[0135] A redistribution layer 40 is provided on the passivation film 32. The redistribution layer 40 has an insulating layer 42 provided on the passivation film 32, redistribution lines 46 provided on the insulating layer 42, and an insulating layer 44 provided on the insulating layer 42 and the redistribution lines 46. An opening is formed in the insulating layer 42 to connect the redistribution lines 46 to the top-layer wiring 34. An opening is formed in the insulating layer 44 to connect the UBM layer 50 to the redistribution lines 46.

[0136] The bumps 52 are electrically connected to the rewirings 46 via a UBM (Under Bump Metallurgy) layer 50. The semiconductor device 100 is connected to a wiring board or the like (not shown) via the bumps 52.

[0137] Such a semiconductor device 100 includes the above-described hardened film. Specifically, the hardened film is used in one or more of the semiconductor device 100 selected from the group consisting of the passivation film 32, the insulating layer 42, and the insulating layer 44. The hardened film has excellent resistance to brittle fracture and high patterning accuracy, so that the semiconductor device 100 can be realized with a highly reliable redistribution layer 40 and high wiring density.

[0138] 4. Effects of the Embodiments As described above, the photosensitive resin composition according to the embodiments is a photosensitive resin composition used in producing a cured film of a semiconductor device 100, and includes a phenolic resin (A), a crosslinking agent (B), and an acid generator (C). The crosslinking agent (B) includes a first component (B1) that is solid at room temperature and a second component (B2) that is liquid at room temperature. The cured product has a tensile elongation of 25% or more. Furthermore, when used to form a trench pattern 22 having a trench 26 with a width of 10 μm and a film thickness of 5 μm, the taper angle θ of the end face 252 facing the trench 26 in the cross section of the trench pattern 22 is 50° or more.

[0139] This configuration allows for the realization of a photosensitive resin composition that can produce a cured film that has excellent resistance to brittle fracture and high patterning accuracy. The cured film produced using this composition can be used in semiconductor devices, contributing to the realization of, for example, a redistribution layer with high definition and reliability. This allows for improved wiring density in the redistribution layer and improved resistance to temperature cycle tests, etc.

[0140] In the photosensitive resin composition according to the embodiment, the first component (B1) contains a urea compound and an epoxy compound, which can particularly improve the deformation resistance of the photosensitive coating.

[0141] In the photosensitive resin composition according to the above embodiment, the epoxy compound contained in the first component (B1) contains an aromatic ring.

[0142] This configuration allows the formation of a rigid structure with stable properties derived from the aromatic rings in the cured film, while also facilitating the formation of a flexible structure between the aromatic rings and the epoxy groups, thereby providing a cured film that exhibits both good mechanical properties and high elongation.

[0143] In the photosensitive resin composition according to the above embodiment, the epoxy compound contained in the first component (B1) has three or more functional groups.

[0144] According to this configuration, the number of crosslinking points in the first component (B1) is relatively large. Therefore, a cured product with good mechanical properties can be produced. Furthermore, trifunctional epoxy compounds, in particular, have both a high number of crosslinking points and flexibility in the molecular chain. Therefore, a cured film with a good balance of good mechanical properties and high elongation can be obtained. As a result, a cured film with particularly good resistance to brittle fracture due to temperature changes, etc. can be obtained.

[0145] In the photosensitive resin composition according to the above embodiment, the second component (B2) contains a difunctional phenoxy-type epoxy resin.

[0146] This configuration facilitates elongation of the molecular chain, imparting high flexibility to the cured film. As a result, a cured film with particularly high elongation can be obtained. Furthermore, the inclusion of an aromatic ring enhances the mechanical properties (e.g., breaking strength) of the cured film.

[0147] In the photosensitive resin composition according to the above embodiment, the average number of functional groups per molecule of the crosslinking agent (B) is 2.4 or more and 3.6 or less.

[0148] According to this configuration, the cured product can have both high elongation, high breaking strength, and high glass transition temperature.

[0149] In the photosensitive resin composition according to the embodiment, the content of the first component (B1) is greater than the content of the second component (B2) in terms of mass ratio.

[0150] This configuration allows the photosensitive coating to have a good balance between deformation resistance and crosslinkability, resulting in a cured film with a sufficiently high tensile elongation and a sufficiently large taper angle at the end faces of the trench pattern formed thereon.

[0151] In the photosensitive resin composition according to the embodiment, the glass transition temperature of the cured product is 230° C. or higher and 300° C. or lower.

[0152] According to this configuration, the cured film made of the cured product can be made more resistant to deformation due to temperature changes.

[0153] In the photosensitive resin composition according to the embodiment, the 5% weight loss temperature of the cured product is 300° C. or higher and 400° C. or lower.

[0154] This configuration ensures the heat resistance of the cured film, thereby realizing a cured film that has good resistance to, for example, a temperature cycle test.

[0155] The cured film according to the embodiment is formed from a cured product of the photosensitive resin composition according to the embodiment.

[0156] According to this configuration, a cured film having excellent resistance to brittle fracture and high patterning accuracy can be obtained.

[0157] The semiconductor device 100 according to the embodiment includes a semiconductor element and a cured film provided on a surface of the semiconductor element. The cured film includes the cured film according to the embodiment.

[0158] With this configuration, the hardened film has excellent resistance to brittle fracture, and therefore the semiconductor device 100 can be obtained with high reliability.

[0159] Although the photosensitive resin composition, cured film, and semiconductor device according to the present invention have been described above based on the above-described embodiments, the present invention is not limited to the above-described embodiments. For example, the photosensitive resin composition, cured film, and semiconductor device according to the present invention may be such that each part of the above-described embodiments is replaced with an arbitrary configuration having the same function, or an arbitrary component is added to the above-described embodiments.

[0160] Next, specific examples of the present invention will be described. 5. Preparation of Photosensitive Resin Composition The components shown in Tables 1 to 3 were mixed by stirring under a nitrogen atmosphere, and then filtered through a polyethylene filter with a pore size of 0.2 μm to prepare a varnish-like photosensitive resin composition. Details of each component shown in Tables 1 to 3 are as follows.

[0161] Phenolic resin (A) Biphenyl-type phenolic resin (a1-1): a biphenyl-type phenolic resin having a structure represented by the following formula (a1), manufactured by Sumitomo Bakelite Co., Ltd., PR-X21024, Mw=45,000

[0162]

[0163] - Method for producing biphenyl-type phenolic resin (a1-1) 186.2 g (1.00 mol) of 4,4'-biphenol, 86.5 g (0.8 mol) of p-cresol, 28.5 g (0.94 mol) of formaldehyde, 15.5 g (0.09 mol) of p-toluenesulfonic acid, and 308 g of γ-butyrolactone were charged into a four-necked glass round-bottom flask equipped with a thermometer, a stirrer, a raw material inlet, and a dry nitrogen gas inlet tube. Then, a polycondensation reaction was carried out at 100°C for 5.5 hours while flowing nitrogen into the round-bottom flask and refluxing the reaction solution in an oil bath. Next, the resulting reaction solution was cooled to room temperature, and 411 g of acetone was added and stirred until homogeneous. The reaction solution in the round-bottom flask was then added dropwise to 10 L of water, resulting in precipitation of the resin component. Next, the precipitated resin component was collected by filtration and then vacuum dried at 60° C. to obtain a biphenyl-type phenolic resin (a1-1) having the structure represented by the above formula (a1).

[0164] Biphenyl-type phenolic resin (a1-2): Biphenyl-type phenolic resin having a structure represented by the above formula (a1), manufactured by Sumitomo Bakelite Co., Ltd., PR-X21024, Mw = 11,000

[0165] - Method for producing biphenyl-type phenolic resin (a1-2) 186.2 g (1.00 mol) of 4,4'-biphenol, 86.5 g (0.8 mol) of p-cresol, 24.0 g (0.8 mol) of formaldehyde, 11.3 g (0.09 mol) of oxalic acid dihydrate, and 308 g of γ-butyrolactone were charged into a four-necked glass round-bottom flask equipped with a thermometer, a stirrer, a raw material inlet, and a dry nitrogen gas inlet tube. Then, a polycondensation reaction was carried out at 100°C for 6 hours while flowing nitrogen into the round-bottom flask and refluxing the reaction solution in an oil bath. Next, the resulting reaction solution was cooled to room temperature, and 411 g of acetone was added and stirred until homogeneous. The reaction solution in the round-bottom flask was then added dropwise to 10 L of water to precipitate the resin component. Next, the precipitated resin component was collected by filtration and then vacuum dried at 60° C. to obtain a biphenyl-type phenolic resin (a1-2) having the structure represented by the above formula (a1).

[0166] Aralkyl phenol resin (a2): KAYAHARD, GPH-103, manufactured by Nippon Kayaku Co., Ltd.

[0167] Crosslinking agent (B) First component (B1) which is solid at room temperature Urea compound (b1-1, tetrafunctional compound): Crolin-318 manufactured by Daito Chemix Co., Ltd. Urea compound (b1-2, trifunctional compound): Nikalac MX-270 manufactured by Sanwa Chemical Co., Ltd. Epoxy compound (b1-2, trifunctional compound): Techmore VG3101L manufactured by Printec Co., Ltd. Second component (B2) which is liquid at room temperature Urea compound (b2-1, bifunctional compound): Nikalac MX-280 manufactured by Sanwa Chemical Co., Ltd. Urea compound (b2-2, tetrafunctional compound): Nikalac MX-279 manufactured by Sanwa Chemical Co., Ltd. Epoxy compound (b2-3, bifunctional compound): YX-7105 manufactured by Mitsubishi Chemical Corporation

[0168] Acid generator (C) Thermal acid generator c1-1: a compound represented by the following formula (c1-1) (Sanshin Chemical Industry Co., Ltd., San-Aid SI-B3A)

[0169]

[0170] Thermal acid generator c1-2: a compound represented by the following formula (c1-2) (Sanshin Chemical Industry Co., Ltd., San-Aid SI-150)

[0171]

[0172] Photoacid generator c2-1: a naphthoquinone diazide compound having a structure represented by the following formula (NQD-5):

[0173]

[0174] Photoacid generator c2-2: a naphthoquinone diazide compound having a structure represented by the following formula (NQD-4):

[0175]

[0176] Adhesion aid (D) Adhesion aid d1: 3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403E

[0177] Solvents Solvent 1: γ-butyrolactone (GBL), manufactured by Sanwa Yuka Kogyo Co., Ltd.

[0178] Tables 1 to 3 show the average number of functional groups per molecule of the crosslinking agent (B) and the compounding ratio B1 / B2.

[0179] 6. Properties of the Cured Product The following properties were obtained for the cured product of the photosensitive resin composition.

[0180] 6.1 Tensile elongation Samples for calculating the tensile elongation of the cured product were prepared using the method described above. Tensile tests were performed on the prepared samples to calculate the tensile elongation. The calculation results are shown in Tables 1 to 3.

[0181] 6.2. Taper Angle of End Faces Using the method described above, specimens were prepared to measure the taper angles of the end faces of trench patterns. The taper angles θ of the prepared specimens were measured. The measurement results are shown in Tables 1 to 3.

[0182] 7. Evaluation of Cured Product The cured products of the photosensitive resin compositions were evaluated for the following physical properties.

[0183] 7.1 Tensile Break Strength Samples for measuring the tensile break strength of the cured products were prepared using the method described above. Tensile tests were performed on the prepared samples to measure the tensile break strength. The measurement results are shown in Tables 1 to 3.

[0184] 7.2. Glass Transition Temperature (Tg) Samples were prepared using the method described above to determine the glass transition temperature (Tg) of the cured product. Dynamic viscoelasticity measurements were performed on the prepared samples to determine the glass transition temperature. The results are shown in Tables 1 to 3.

[0185] 7.3. Coefficient of Linear Thermal Expansion (CTE) Samples were prepared using the method described above to calculate the coefficient of linear thermal expansion (CTE) of the cured product. Thermomechanical analysis was performed on the prepared samples to determine the coefficient of linear thermal expansion. The derived results are shown in Tables 1 to 3.

[0186] 7.4.5% Weight Loss Temperature (Td5) Using the method described above, samples were prepared to calculate the 5% weight loss temperature (Td5) of the cured product. Thermogravimetry and differential thermal analysis were performed on the prepared samples to determine the 5% weight loss temperature. The derived results are shown in Tables 1 to 3.

[0187] 7.5. Resistance to Temperature Cycle Test (TC) The photosensitive resin composition was applied to an 8-inch silicon wafer using a spin coater, and the resulting coating was cured at 220°C for 240 minutes to obtain a cured film. The resulting cured film was then subjected to a temperature cycle test (TC) 200 times under atmospheric air conditions, with temperatures ranging from -65 to 150°C and a 15-minute pause, with the starting and ending temperatures varying from -65°C. The cured film was then cut into a grid pattern using the cross-cut method specified in JIS K 5600-5-6. The cured film cut into grid patterns was then subjected to a tape peel test, and the percentage of the cured film remaining on the wafer (residual rate) was calculated. The calculated residual rate was then used to evaluate the resistance to the temperature cycle test according to the following evaluation criteria. The evaluation results are shown in Tables 1 to 3.

[0188] A: The resistance to the temperature cycle test is particularly good (survival rate is 100%). B: The resistance to the temperature cycle test is good (survival rate is 75% or more and less than 100%). C: The resistance to the temperature cycle test is poor (survival rate is less than 75%).

[0189] The patterning accuracy of the cured film was evaluated by comparing the measured taper angles of the end faces with the following evaluation criteria. The evaluation results are shown in Tables 1 to 3.

[0190] A: The patterning accuracy is particularly good (the taper angle of the end face is 60° or more). B: The patterning accuracy is good (the taper angle of the end face is 50° or more and less than 60°). C: The patterning accuracy is good (the taper angle of the end face is less than 50°).

[0191]

[0192]

[0193]

[0194] The evaluation results shown in Tables 1 to 3 reveal the following: By including the first component (B1) and the second component (B2) in the crosslinking agent (B), it was possible to increase both the tensile elongation and the taper angle of the end faces of the cured product compared to when either component was not included. This resulted in improved resistance to temperature cycle tests and improved patterning accuracy.

[0195] By optimizing the average number of functional groups in the crosslinking agent (B), it was possible to achieve a good balance between the tensile elongation of the cured product and the taper angle of the end faces.

[0196] According to the present invention, it is possible to provide a photosensitive resin composition that has excellent resistance to brittle fracture and that can produce a cured film with high patterning accuracy. Therefore, the present invention has industrial applicability.

[0197] 2 Test object 21 Silicon wafer 22 Trench pattern 24 Hardened film 26 Trench 30 Interlayer insulating film 32 Passivation film 34 Top layer wiring 40 Rewiring layer 42 Insulating layer 44 Insulating layer 46 Rewiring 50 UBM layer 52 Bump 100 Semiconductor device 212 Upper surface 252 End surface θ Taper angle

Claims

1. A photosensitive resin composition used in the manufacture of cured films for semiconductor devices, Phenolic resin (A) and Crosslinking agent (B), Acid generator (C), Includes, The crosslinking agent (B) comprises a first component that is solid at room temperature and a second component that is liquid at room temperature. The mixing ratio of the first component to the second component is 1.5 or more by mass. The tensile elongation of the cured product is 25% or more. A photosensitive resin composition characterized in that, when used to form a trench pattern with a trench width of 10 μm and a film thickness of 5 μm, the taper angle of the end face facing the trench in the cross-section of the trench pattern is 50° or more.

2. The photosensitive resin composition according to claim 1, wherein the first component comprises a urea-based compound and an epoxy-based compound.

3. The photosensitive resin composition according to claim 2, wherein the epoxy compound contained in the first component contains an aromatic ring.

4. The photosensitive resin composition according to claim 2 or 3, wherein the number of functional groups of the epoxy compound contained in the first component is 3 or more.

5. The photosensitive resin composition according to claim 1, wherein the second component comprises a bifunctional phenoxy-type epoxy resin.

6. The photosensitive resin composition according to claim 1 or 2, wherein the average number of functional groups per molecule of the crosslinking agent (B) is 2.4 or more and 3.6 or less.

7. The photosensitive resin composition according to claim 1 or 2, wherein the glass transition temperature of the cured product is 230°C or higher and 300°C or lower.

8. The photosensitive resin composition according to claim 1 or 2, wherein the temperature at which the cured product loses 5% of its weight is 300°C or more and 400°C or less.

9. A cured film characterized by being composed of a cured product of the photosensitive resin composition described in claim 1 or 2.

10. Semiconductor elements and The cured film according to claim 9 is provided on the surface of the semiconductor element, A semiconductor device characterized by comprising the following features.