Novolac-type phenolic resin, photosensitive resin composition, resin film, and electronic device

Abstract

To provide a novolac-type phenolic resin that allows production of a photosensitive resin composition having an improved balance between developability and heat resistance, and to provide a photosensitive resin composition with an improved balance of developability and heat resistance.SOLUTION: A novolac-type phenolic resin includes a structural unit (A) containing a structural unit (A1) derived from bisphenols, and a structural unit (B) derived from aldehydes, wherein the molar ratio (B) / (A) of the structural unit (B) to the structural unit (A) is 1.30 or more and less than 2.00.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a novolak-type phenol resin, a photosensitive resin composition, a resin film, and an electronic device.

Background Art

[0002] The photosensitive resin composition contains, for example, a photosensitizer and an alkali-soluble resin (for example, a novolak-type phenol resin). As technologies related to the novolak-type phenol resin used in the photosensitive resin composition, for example, the technologies described in Patent Documents 1 and 2 can be mentioned.

[0003] Patent Document 1 proposes a novolak-type phenol resin for a photoresist composition that exhibits high flexibility and has both high resolution and a high residual film ratio, and a photoresist composition containing the novolak-type phenol resin. As an object, a novolak-type phenol resin characterized by being obtained by subjecting a phenol component (a) containing bisphenols having a substituent at the 2,2'-position and a monoaldehyde component (b) to a polycondensation reaction is described.

[0004] Patent Document 2 proposes a novolak-type phenol resin for a photoresist composition that exhibits high flexibility and has both high resolution and a high residual film ratio, and a photoresist composition containing the novolak-type phenol resin. As an object, a novolak-type phenol resin obtained by subjecting a phenol component (a) containing bisphenols and an aldehyde component (b) mainly composed of aliphatic polyaldehydes having 3 or more carbon atoms to a polycondensation reaction is described.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention provides a novolak-type phenol resin capable of obtaining a photosensitive resin composition with an improved balance of developability and heat resistance, and a photosensitive resin composition with an improved balance of developability and heat resistance.

Means for Solving the Problems

[0007] The inventors of the present invention have conducted intensive studies to achieve the above problems. As a result, they have found that by setting the molar ratio of structural units in the novolak-type phenol resin within a specific range, the balance of developability and heat resistance of the resulting photosensitive resin composition can be improved, and thus the present invention has been completed.

[0008] According to the present invention, there are provided a novolak-type phenol resin, a photosensitive resin composition, a resin film, and an electronic device as shown below.

[0009] [1] A structural unit (A) containing a structural unit (A1) derived from bisphenols, and A structural unit (B) derived from aldehydes, and including, A novolak-type phenol resin in which the molar ratio (B) / (A) of the structural unit (A) to the structural unit (B) is 1.30 or more and less than 2.00. [2] The structural unit (A) further includes a structural unit (A2) derived from xylenols, and the novolak-type phenol resin according to [1] above. [3] When the total content of the structural unit (A) is 100 mol%, the content of the structural unit (A1) is 10 mol% or more and 99 mol% or less, and the novolak-type phenol resin according to [2] above. [4] The novolak type phenol resin according to [2] or [3] above, wherein the content of the structural unit (A2) is 1 mol% or more and 90 mol% or less when the total content of the structural units (A) is 100 mol%. [5] The novolak type phenol resin according to any one of [2] to [4] above, wherein the xylenols contain one or more selected from the group consisting of 2,5-xylenol, 2,4-xylenol, and 3,5-xylenol. [6] The novolak type phenol resin according to any one of [1] to [5] above, wherein the bisphenols contain one or more selected from the group consisting of bisphenol C, bisphenol A, and bisphenol F. [7] The novolak type phenol resin according to any one of [1] to [6] above, wherein the content of the structural unit (A) is 5 mol% or more and 45 mol% or less when the total of the structural units constituting the novolak type phenol resin is 100 mol%. [8] The novolak type phenol resin according to any one of [1] to [7] above, wherein the aldehydes contain one or more selected from the group consisting of formaldehyde, paraformaldehyde, acetaldehyde, and salicylaldehyde. [9] The novolak type phenol resin according to any one of [1] to [8] above, wherein the mass average molecular weight in terms of polystyrene of the novolak type phenol resin is 1000 or more and 100000 or less.

[10] The novolak type phenol resin according to any one of [1] to [9] above, wherein the alkali dissolution rate of the novolak type phenol resin by the following (Method 1) is 1 Å / second or more and 4000 Å / second or less. (Method 1) The novolak-type phenol resin is prepared as a 25% by mass propylene glycol monomethyl ether acetate solution. This solution is applied onto a silicon wafer using a spin coater to a thickness H of 1 μm, and dried on a hot plate at 110°C for 90 seconds. Then, the novolak-type phenol resin applied to the silicon wafer is dissolved with a developer (2.38% aqueous solution of tetramethylammonium hydroxide), and the time T for the novolak-type phenol resin to dissolve is visually measured. Then, the alkali dissolution rate is calculated from the following formula. (Alkali dissolution rate) [Å / sec] = (Thickness H) / (Time T for the novolak-type phenol resin to dissolve)

[11] The novolak-type phenol resin according to any one of [1] to

[10] above, wherein the total content of phenols and cresols calculated from the area ratio by the following (Method 2) is 500 ppm or less. (Method 2) Using a GC-MS (gas chromatography mass spectrometer), 1 μL of the novolak-type phenol resin is directly introduced into the injection port of the GC-MS to measure the mass spectrum of the novolak-type phenol resin. Then, based on the calibration curve prepared using phenols and cresols of known concentrations, the total content of phenols and cresols is calculated from the area ratio.

[12] A photosensitive resin composition containing the novolak-type phenol resin according to any one of [1] to

[11] above, a photosensitizer, and a solvent.

[13] The photosensitive resin composition according to

[12] above, wherein the content of the novolak-type phenol resin is 10% by mass or more and 40% by mass or less when the total components of the photosensitive resin composition are 100% by mass.

[14] The photosensitive resin composition according to

[12] or

[13] above, wherein the photosensitizer contains one or more selected from the group consisting of polyhydroxybenzophenones, bis[(poly)hydroxyphenyl]alkanes, tris(hydroxyphenyl)methanes or methyl-substituted products thereof, and bis(cyclohexylhydroxyphenyl)(hydroxyphenyl)methanes or methyl-substituted products thereof.

[15] The photosensitive resin composition according to any one of

[12] to

[14] above, wherein the content of the photosensitizer is 1% by mass or more and 10% by mass or less when the total components of the photosensitive resin composition are 100% by mass.

[16] The photosensitive resin composition according to any one of

[12] to

[15] above, wherein the solvent contains one or more selected from the group consisting of ethylene glycol alkyl ethers, diethylene glycol dialkyl ethers, ethylene glycol alkyl ether acetates, propylene glycol alkyl ether acetates, ketones, cyclic ethers, and esters.

[17] The photosensitive resin composition according to any one of

[12] to

[16] above, wherein the content of the solvent is 50% by mass or more and 90% by mass or less when the total components of the photosensitive resin composition are 100% by mass.

[18] The photosensitive resin composition according to any one of

[12] to

[17] above, which can be used for a photoresist.

[19] A resin film containing a cured product of the photosensitive resin composition according to any one of

[12] to

[18] above.

[20] An electronic device including the resin film according to

[19] above. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a novolac-type phenol resin capable of obtaining a photosensitive resin composition with an improved performance balance between developability and heat resistance, and a photosensitive resin composition with an improved performance balance between developability and heat resistance.

Mode for Carrying Out the Invention

[0011] Hereinafter, the present invention will be described based on embodiments. In this embodiment, "A to B" indicating a numerical range represents A or more and B or less unless otherwise specified.

[0012] <Novolak-type phenol resin> The novolak-type phenol resin of this embodiment contains a structural unit (A) containing a structural unit (A1) derived from bisphenols and a structural unit (B) derived from aldehydes, and the molar ratio (B) / (A) of the structural unit (A) to the structural unit (B) is 1.30 or more and less than 2.00.

[0013] From the viewpoint of improving the performance balance between the developability and heat resistance of the resulting photosensitive resin composition, the molar ratio (B) / (A) of the novolak-type phenol resin of this embodiment is preferably 1.35 or more, more preferably 1.40 or more, still more preferably 1.45 or more, still more preferably 1.50 or more, still more preferably 1.55 or more, still more preferably 1.60 or more, still more preferably 1.65 or more, still more preferably 1.70 or more, and is preferably 1.95 or less, more preferably 1.90 or less, still more preferably 1.85 or less, still more preferably 1.80 or less. That is, from the viewpoint of improving the performance balance between the developability and heat resistance of the resulting photosensitive resin composition, the molar ratio (B) / (A) of the novolak-type phenol resin of this embodiment is preferably 1.35 or more and 1.95 or less, more preferably 1.40 or more and 1.95 or less, still more preferably 1.45 or more and 1.95 or less, still more preferably 1.50 or more and 1.95 or less, still more preferably 1.55 or more and 1.95 or less, still more preferably 1.60 or more and 1.90 or less, still more preferably 1.65 or more and 1.85 or less, still more preferably 1.70 or more and 1.80 or less.

[0014] [Structural unit (A)] The novolak-type phenol resin of this embodiment contains a structural unit (A) containing a structural unit (A1) derived from bisphenols. The bisphenols of this embodiment preferably include one or more selected from the group consisting of bisphenol C, bisphenol A, bisphenol F, bisphenol E, bisphenol S, bisphenol M, bisphenol P, and bisphenol Z. From the viewpoint of improving the performance balance between developability and heat resistance of the resulting photosensitive resin composition, more preferably, it includes one or more selected from the group consisting of bisphenol C, bisphenol A, and bisphenol F, and even more preferably, it includes bisphenol C.

[0015] From the viewpoint of further improving the performance balance between developability and heat resistance of the resulting photosensitive resin composition, the structural unit (A) in the novolak-type phenol resin of this embodiment preferably further includes a structural unit (A2) derived from xylenols. The xylenols of this embodiment preferably include one or more selected from the group consisting of 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, and 3,5-xylenol. From the viewpoint of improving the performance balance between developability and heat resistance of the resulting photosensitive resin composition, more preferably, it includes one or more selected from the group consisting of 2,5-xylenol, 2,4-xylenol, and 3,5-xylenol, and even more preferably, it includes 2,5-xylenol.

[0016] When the novolak type phenol resin of the present embodiment further contains a structural unit (A2) derived from xylenols, the content of the structural unit (A1) of the novolak type phenol resin of the present embodiment, from the viewpoint of improving the performance balance between developability and heat resistance of the resulting photosensitive resin composition, when the total content of the structural unit (A) is 100 mol%, is preferably 10 mol% or more, more preferably 20 mol% or more, still more preferably 30 mol% or more, still more preferably 40 mol% or more, still more preferably 45 mol% or more, still more preferably 50 mol% or more, and is preferably 99 mol% or less, more preferably 95 mol% or less, still more preferably 90 mol% or less, still more preferably 80 mol% or less, still more preferably 70 mol% or less. That is, the content of the structural unit (A1) of the novolak type phenol resin of the present embodiment, from the viewpoint of improving the performance balance between developability and heat resistance of the resulting photosensitive resin composition, when the total content of the structural unit (A) is 100 mol%, is preferably 10 mol% or more and 99 mol% or less, more preferably 20 mol% or more and 95 mol% or less, still more preferably 30 mol% or more and 90 mol% or less, still more preferably 40 mol% or more and 80 mol% or less, still more preferably 45 mol% or more and 70 mol% or less, still more preferably 50 mol% or more and 70 mol% or less.

[0017] When the novolak type phenol resin of the present embodiment further contains a structural unit (A2) derived from xylenols, the content of the structural unit (A2) of the novolak type phenol resin of the present embodiment, from the viewpoint of improving the performance balance between developability and heat resistance of the resulting photosensitive resin composition, when the total content of the structural unit (A) is 100 mol%, is preferably 1 mol% or more, more preferably 5 mol% or more, still more preferably 10 mol% or more, still more preferably 20 mol% or more, still more preferably 30 mol% or more, and is preferably 90 mol% or less, more preferably 80 mol% or less, still more preferably 70 mol% or less, still more preferably 60 mol% or less, still more preferably 55 mol% or less, still more preferably 50 mol% or less. That is, from the viewpoint of improving the performance balance between the developability and heat resistance of the resulting photosensitive resin composition, when the total content of the structural unit (A) is 100 mol%, the content of the structural unit (A2) in the novolak-type phenol resin of the present embodiment is preferably 1 mol% or more and 90 mol% or less, more preferably 5 mol% or more and 80 mol% or less, still more preferably 10 mol% or more and 70 mol% or less, still more preferably 20 mol% or more and 60 mol% or less, still more preferably 20 mol% or more and 55 mol% or less, and still more preferably 30 mol% or more and 50 mol% or less.

[0018] From the viewpoint of improving the performance balance between the developability and heat resistance of the resulting photosensitive resin composition, when the total of the structural units constituting the novolak-type phenol resin is 100 mol%, the content of the structural unit (A) in the novolak-type phenol resin of the present embodiment is preferably 5 mol% or more, more preferably 10 mol% or more, still more preferably 15 mol% or more, still more preferably 20 mol% or more, still more preferably 25 mol% or more, and still more preferably 30 mol% or more, and is preferably 45 mol% or less, more preferably 44 mol% or less, still more preferably 43 mol% or less, still more preferably 42 mol% or less, still more preferably 41 mol% or less, and still more preferably 40 mol% or less. That is, from the viewpoint of improving the performance balance between the developability and heat resistance of the resulting photosensitive resin composition, when the total of the structural units constituting the novolak-type phenol resin is 100 mol%, the content of the structural unit (A) in the novolak-type phenol resin of the present embodiment is preferably 5 mol% or more and 45 mol% or less, more preferably 10 mol% or more and 44 mol% or less, still more preferably 15 mol% or more and 43 mol% or less, still more preferably 20 mol% or more and 42 mol% or less, still more preferably 25 mol% or more and 41 mol% or less, and still more preferably 30 mol% or more and 40 mol% or less.

[0019] [Structural unit (B)] The novolak-type phenol resin of the present embodiment contains a structural unit (B) derived from aldehydes. The aldehydes of this embodiment preferably contain one or more selected from the group consisting of formaldehyde, alkyl aldehydes, unsaturated alkyl aldehydes, hydroxybenzaldehydes, aromatic aldehydes, and dialdehydes.

[0020] The alkyl aldehydes of this embodiment preferably contain one or more selected from the group consisting of paraformaldehyde, acetaldehyde, propyl aldehyde, butyl aldehyde, isobutyl aldehyde, isovaleraldehyde, hexyl aldehyde, and octyl aldehyde. The unsaturated alkyl aldehydes of this embodiment preferably contain one or more selected from the group consisting of acrolein and crotonaldehyde. The hydroxybenzaldehydes of this embodiment preferably contain one or more selected from the group consisting of salicylaldehyde and para-hydroxybenzaldehyde, and more preferably contain salicylaldehyde. The aromatic aldehydes of this embodiment preferably contain one or more selected from the group consisting of benzaldehyde and phthalaldehyde. The dialdehydes of this embodiment preferably contain one or more selected from the group consisting of glyoxal and glutaraldehyde.

[0021] From the viewpoint of improving the performance balance between the developability and heat resistance of the resulting photosensitive resin composition, the aldehydes of this embodiment preferably contain one or more selected from the group consisting of formaldehyde, paraformaldehyde, acetaldehyde, and salicylaldehyde, and more preferably contain one or two selected from the group consisting of formaldehyde and salicylaldehyde.

[0022] From the viewpoint of improving the performance balance between the developability and heat resistance of the resulting photosensitive resin composition, the content of the structural unit (B) in the novolak-type phenol resin of the present embodiment, when the total of the structural units constituting the novolak-type phenol resin is 100 mol%, is preferably 55 mol% or more, more preferably 56 mol% or more, still more preferably 57 mol% or more, still more preferably 58 mol% or more, still more preferably 59 mol% or more, still more preferably 60 mol% or more, and is preferably 95 mol% or less, more preferably 90 mol% or less, still more preferably 85 mol% or less, still more preferably 80 mol% or less, still more preferably 75 mol% or less, still more preferably 70 mol% or less. That is, from the viewpoint of improving the performance balance between the developability and heat resistance of the resulting photosensitive resin composition, the content of the structural unit (B) in the novolak-type phenol resin of the present embodiment, when the total of the structural units constituting the novolak-type phenol resin is 100 mol%, is preferably 55 mol% or more and 95 mol% or less, more preferably 56 mol% or more and 90 mol% or less, still more preferably 57 mol% or more and 85 mol% or less, still more preferably 58 mol% or more and 80 mol% or less, still more preferably 59 mol% or more and 75 mol% or less, still more preferably 60 mol% or more and 70 mol% or less.

[0023] [Physical Properties] From the viewpoint of improving the performance balance between the developability and heat resistance of the resulting photosensitive resin composition, the polystyrene-reduced mass average molecular weight of the novolak-type phenol resin of the present embodiment is preferably 1000 or more and 100000 or less, more preferably 1500 or more and 90000 or less, still more preferably 2000 or more and 80000 or less, still more preferably 2500 or more and 70000 or less, still more preferably 3000 or more and 60000 or less, still more preferably 3500 or more and 50000 or less, still more preferably 4000 or more and 40000 or less, still more preferably 4500 or more and 30000 or less, still more preferably 5000 or more and 20000 or less.

[0024] The alkali dissolution rate of the novolak-type phenol resin of the present embodiment by the following (Method 1) is preferably 1 Å / sec or more and 4000 Å / sec or less, more preferably 2 Å / sec or more and 3000 Å / sec or less, still more preferably 3 Å / sec or more and 2000 Å / sec or less, still more preferably 4 Å / sec or more and 1000 Å / sec or less, still more preferably 5 Å / sec or more and 750 Å / sec or less, still more preferably 5 Å / sec or more and 500 Å / sec or less, still more preferably 5 Å / sec or more and 300 Å / sec or less, from the viewpoint of improving the performance balance between the developability and heat resistance of the resulting photosensitive resin composition.

[0025] (Method 1) The novolak-type phenol resin is prepared as a 25% by mass propylene glycol monomethyl ether acetate solution. This solution is applied onto a silicon wafer with a spin coater to a thickness H of 1 μm and dried on a hot plate at 110 °C for 90 seconds. Then, the novolak-type phenol resin applied to the silicon wafer is dissolved with a developer (2.38% aqueous tetramethylammonium hydroxide solution), and the time T for the novolak-type phenol resin to dissolve is visually measured. Then, the alkali dissolution rate is calculated from the following formula. (Alkali dissolution rate) [Å / sec] = (Thickness H) / (Time T for the novolak-type phenol resin to dissolve)

[0026] The total content of phenols and cresols calculated from the area ratio of the novolak-type phenol resin of the present embodiment by the following (Method 2) is preferably 500 ppm or less, more preferably 400 ppm or less, still more preferably 300 ppm or less, still more preferably 200 ppm or less, still more preferably 100 ppm or less, still more preferably 50 ppm or less, still more preferably 25 ppm or less, from the viewpoint of improving the performance balance between the developability and heat resistance of the resulting photosensitive resin composition. The lower limit is not particularly limited, and may be, for example, 0 ppm or more.

[0027] (Method 2) Using a GC-MS (gas chromatograph-mass spectrometer), the mass spectrum of the novolak-type phenolic resin is measured by directly introducing 1 μL of the novolak-type phenolic resin into the injection port of the GC-MS. Then, based on the calibration curve prepared using phenols and cresols of known concentrations, the total content of phenols and cresols is calculated from the area ratio. The conditions of the GC-MS are, for example, as follows. Extraction solvent: normal hexane GC injection port temperature: 250 °C GC oven temperature: Held at 40 °C for 5 minutes and then heated to 300 °C and held for 9 minutes MS interface temperature: 300 °C Chromatograph: Agilent 6890N (manufactured by Agilent Technologies) Mass detector: Agilent 5975B (manufactured by Agilent Technologies) Analysis column: HP-5MS (manufactured by Agilent Technologies)

[0028] <Method for producing novolak-type phenolic resin> The method for producing the novolak-type phenolic resin of the present embodiment includes, for example, a reaction step of reacting bisphenols and aldehydes in the presence of an acid catalyst, and an unreacted bisphenol removal step of removing unreacted bisphenols remaining unreacted in the reaction step. The details of each step will be described below.

[0029] [Reaction step] In the reaction step, first, a reaction apparatus equipped with a stirrer, a thermometer, and a heat exchanger is charged with bisphenols and an acidic catalyst in predetermined compounding amounts.

[0030] Next, after raising the temperature inside the reaction apparatus to a predetermined temperature, the sequential addition of aldehydes is started. The sequential addition temperature and time can be appropriately set according to the reactivity of the monomers and the desired properties, but are set to a level that enables stable and economical production.

[0031] The acidic catalyst is not particularly limited, and examples thereof include inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, and boric acid, and organic acids such as oxalic acid, acetic acid, and p-toluenesulfonic acid. These may be used alone or in combination. Note that as the acidic catalyst, those that can be easily removed from the reaction system by decomposition, sublimation, etc. during monomer removal are preferred. Also, the amount of the acidic catalyst used is preferably such that the pH in the reaction system is in the range of 1 to 6.

[0032] The aldehydes may be charged into the flask together with the bisphenols and the catalyst before raising the temperature of the reaction system, or may be sequentially added after raising the temperature of the reaction system. When the aldehydes are sequentially added, the temperature is preferably 70 to 130 °C, more preferably 90 to 110 °C. By doing so, the reaction can proceed at an appropriate rate without a rapid increase in temperature.

[0033] The sequential addition time of the aldehydes is preferably 30 to 300 minutes, more preferably 60 to 180 minutes. By doing so, the reaction can proceed at an appropriate rate without a rapid increase in temperature.

[0034] Note that after the sequential addition of the aldehydes is completed, the reaction can be continued as necessary. Also, during the sequential addition and reaction of the aldehydes, a reaction solvent can be added and used as necessary. The type of the solvent is not particularly limited, but a solvent that can dissolve the novolak-type phenol resin is preferred. Examples of such solvents include ketones such as methyl ethyl ketone and methyl isobutyl ketone, alcohols such as butanol, ether alcohols such as ethoxyethanol, ethylene glycol alkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol alkyl ether acetates such as ethyl cellosolve acetate, and propylene glycol alkyl ether acetates such as propylene glycol monomethyl ether acetate.

[0035] [Unreacted bisphenol removal step] As a step for removing unreacted bisphenol, heat treatment is carried out to remove unreacted bisphenols remaining unreacted in the reaction apparatus. The conditions of the heat treatment are adjusted according to the type and components of the bisphenols used. For example, it is 150 to 230 °C and 1 to 5 hours under normal pressure. Note that the heat treatment is preferably carried out under a reduced pressure of -0.08 MPa or less.

[0036] <Photosensitive resin composition> The photosensitive resin composition of the present embodiment contains the novolak type phenol resin of the present embodiment, a photosensitizer, and a solvent.

[0037] From the viewpoint of further improving the performance balance between developability and heat resistance, when the total amount of the components of the photosensitive resin composition is 100% by mass, the content of the novolak type phenol resin in the photosensitive resin composition of the present embodiment is preferably 10% by mass or more and 40% by mass or less, more preferably 12% by mass or more and 40% by mass or less, still more preferably 14% by mass or more and 35% by mass or less, still more preferably 16% by mass or more and 30% by mass or less, still more preferably 18% by mass or more and 25% by mass or less.

[0038] (Photosensitizer) The photosensitive resin composition of the present embodiment contains a photosensitizer. Thereby, it becomes possible to form a pattern through exposure and development.

[0039] From the viewpoint of further improving the performance balance between developability and heat resistance, the photosensitive agent of this embodiment preferably contains one or more selected from the group consisting of polyhydroxybenzophenones, bis[(poly)hydroxyphenyl]alkanes, tris(hydroxyphenyl)methanes or their methyl-substituted products, and bis(cyclohexylhydroxyphenyl)(hydroxyphenyl)methanes or their methyl-substituted products. More preferably, it contains one or more selected from the group consisting of polyhydroxybenzophenones, bis[(poly)hydroxyphenyl]alkanes, tris(hydroxyphenyl)methanes or their methyl-substituted products, and bis(cyclohexylhydroxyphenyl)(hydroxyphenyl)methanes or their methyl-substituted products, and one or more selected from the group consisting of complete ester compounds and partial ester compounds of quinonediazide group-containing sulfonic acids. The polyhydroxybenzophenones preferably contain one or more selected from the group consisting of 2,3,4-trihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,4,6-trihydroxybenzophenone, 2,3,6-trihydroxybenzophenone, 2,3,4-trihydroxy-2'-methylbenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,3',4,4',6-pentahydroxybenzophenone, 2,2',3,4,4'-pentahydroxybenzophenone, 2,2',3,4,5-pentahydroxybenzophenone, 2,3',4,4',5',6-hexahydroxybenzophenone, and 2,3,3',4,4',5'-hexahydroxybenzophenone. Bis[(poly)hydroxyphenyl]alkanes preferably include one or more selected from the group consisting of bis(2,4-dihydroxyphenyl)methane, bis(2,3,4-trihydroxyphenyl)methane, 2-(4-hydroxyphenyl)-2-(4'-hydroxyphenyl)propane, 2-(2,4-dihydroxyphenyl)-2-(2',4'-dihydroxyphenyl)propane, 2-(2,3,4-trihydroxyphenyl)-2-(2',3',4'-trihydroxyphenyl)propane, 4,4'-{1-[4-[2-(4-hydroxyphenyl)-2-propyl]phenyl]ethylidene}bisphenol, 3,3'-dimethyl-{1-[4-[2-(3-methyl-4-hydroxyphenyl)-2-propyl]phenyl]ethylidene}bisphenol. Tris(hydroxyphenyl)methanes or their methyl-substituted derivatives preferably include one or more selected from the group consisting of tris(4-hydroxyphenyl)methane, bis(4-hydroxy-3,5-dimethylphenyl)-4-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-4-hydroxyphenylmethane, bis(4-hydroxy-3,5-dimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-3,4-dihydroxyphenylmethane, bis(4-hydroxy-3,5-dimethylphenyl)-3,4-dihydroxyphenylmethane. Bis(cyclohexylhydroxyphenyl)(hydroxyphenyl)methanes or their methyl-substituted derivatives preferably include bis(3-cyclohexyl-4-hydroxyphenyl)-3-hydroxyphenylmethane, bis(3-cyclohexyl-4-hydroxyphenyl)-2-hydroxyphenylmethane, bis(3-cyclohexyl-4-hydroxyphenyl)-4-hydroxyphenylmethane, bis(5-cyclohexyl-4-hydroxy-2-methylphenyl)-2-hydroxyphenylmethane, bis(5-cyclohexyl-4-hydroxy-2-methylphenyl)-3-hydroxyphenylmethane, bis(5-cyclohexyl-4-hydroxy-2-methylphenyl)-4-hydroxyphenylmethane, bis(3-cyclohexyl-2-hydroxyphenyl)-3-hydroxyphenylmethane, bis(5-cyclohexyl-4-hydroxy-3-methylphenyl)-4-hydroxyphenylmethane, bis(5-cyclohexyl-4-hydroxy-3-methylphenyl)-3-hydroxyphenylmethane, bis(5-cyclohexyl-4-hydroxy-3-methylphenyl)-2-hydroxyphenylmethane, bis(3-cyclohexyl-2-hydroxyphenyl)-4-hydroxyphenylmethane, bis(3-cyclohexyl-2-hydroxyphenyl)-2-hydroxyphenylmethane, bis(5-cyclohexyl-2-hydroxy-4-methylphenyl)-2-hydroxyphenylmethane, bis(5-cyclohexyl-2-hydroxy-4-methylphenyl)-4-hydroxyphenylmethane, and contain one or more selected from the group consisting of them. From the viewpoint of further improving the performance balance between developability and heat resistance, the photosensitive agent of this embodiment preferably contains polyhydroxybenzophenones, more preferably contains 2,3,4-trihydroxybenzophenone, and even more preferably contains the 2,3,4-trihydroxybenzophenone ester of naphthoquinone 1,2-diazide-5-sulfonic acid.

[0040] From the viewpoint of further improving the performance balance between developability and heat resistance, when the total amount of the components of the photosensitive resin composition is 100% by mass, the content of the photosensitizer in the photosensitive resin composition of the present embodiment is preferably 1% by mass or more and 10% by mass or less, more preferably 2% by mass or more and 9% by mass or less, still more preferably 3% by mass or more and 8% by mass or less, still more preferably 4% by mass or more and 7% by mass or less, and still more preferably 4% by mass or more and 6% by mass or less.

[0041] (Solvent) The photosensitive resin composition of the present embodiment contains a solvent. Thereby, the workability when using the photosensitive resin composition of the present embodiment can be improved.

[0042] The solvent of this embodiment preferably includes one or more selected from the group consisting of ethylene glycol alkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, and ethylene glycol monobutyl ether; diethylene glycol dialkyl ethers such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, and diethylene glycol dibutyl ether; ethylene glycol alkyl ether acetates such as methyl cellosolve acetate and ethyl cellosolve acetate; propylene glycol alkyl ether acetates such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and propylene glycol monopropyl ether acetate; ketones such as acetone, methyl ethyl ketone, cyclohexanone, and methyl amyl ketone; cyclic ethers such as dioxane; and esters such as methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl oxyacetate, methyl 2-hydroxy-3-methylbutyrate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, ethyl formate, ethyl acetate, butyl acetate, methyl acetoacetate, and ethyl acetoacetate. From the viewpoint of further improving the performance balance between developability and heat resistance, the solvent of this embodiment more preferably includes propylene glycol alkyl ether acetates, and even more preferably includes propylene glycol monomethyl ether acetate.

[0043] From the viewpoint of further improving the performance balance between developability and heat resistance, when the total components of the photosensitive resin composition are 100% by mass, the content of the solvent in the photosensitive resin composition of this embodiment is preferably 50% by mass or more and 90% by mass or less, more preferably 55% by mass or more and 90% by mass or less, even more preferably 60% by mass or more and 90% by mass or less, even more preferably 65% by mass or more and 85% by mass or less, and even more preferably 70% by mass or more and 80% by mass or less.

[0044] In addition to the components described above, various additives such as surfactants, adhesion improvers, and dissolution accelerators may be used as necessary in the photosensitive resin composition according to this embodiment.

[0045] Moreover, as a method for preparing the photosensitive resin composition according to this embodiment, although not particularly limited, when no filler or pigment is added to the photosensitive resin composition, it is only necessary to mix and stir the various components by a normal method. When adding a filler or pigment, for example, it may be dispersed and mixed using a dispersing device such as a dissolver, a homogenizer, or a three-roll mill. Further, if necessary, it may be filtered using a mesh filter, a membrane filter, or the like.

[0046] The photosensitive resin composition of this embodiment can be used as a photoresist. By performing exposure on the photosensitive resin composition of this embodiment through a mask, a structural change occurs in the photosensitive resin composition in the exposed portion, and the solubility in an alkaline developer can be promoted. On the other hand, in the unexposed portion, a low solubility in the alkaline developer is maintained. Due to the difference in solubility thus generated, the photosensitive resin composition of this embodiment can be used as a photoresist.

[0047] <Resin film> A resin film can be obtained by curing the photosensitive resin composition of this embodiment. That is, the resin film of this embodiment preferably contains a cured product of the photosensitive resin composition of this embodiment. The resin film of this embodiment can be used, for example, as a resist, and can also constitute a permanent film such as a protective film, an interlayer film, or a dam material for an electronic device.

[0048] <Electronic device> The electronic device of this embodiment preferably contains the resin film of this embodiment.

[0049] The electronic device of this embodiment can be manufactured by the following manufacturing method.

[0050] The manufacturing method of the electronic device of the present embodiment is as follows: A film forming step of forming a resin film on a substrate using the photosensitive resin composition of the present embodiment; An exposure step of exposing the resin film; A development step of developing the exposed resin film; and the like. In addition, the manufacturing method of the electronic device of the present embodiment preferably includes a heat curing step of heating and curing the exposed resin film after the above-mentioned development step. Thereby, a resin film containing a cured product of the photosensitive resin composition excellent in chemical resistance and elongation can be obtained.

[0051] The film forming step is performed, for example, by applying a photosensitive resin composition on a substrate. The film forming step can be performed using a spin coater, a bar coater, a spray device, an inkjet device, or the like. Before the next exposure step, it is preferable to perform appropriate heating for the purpose of drying the solvent in the applied photosensitive resin composition. The heating at this time is performed, for example, at a temperature of 80 to 150°C for 1 to 60 minutes. The thickness of the dried resin film appropriately varies depending on the structure of the electronic device to be finally obtained, but is, for example, 1 to 100 μm, preferably 1 to 50 μm.

[0052] The exposure amount in the exposure step is not particularly limited. 100 to 2000 mJ / cm 2 is preferable, and 200 to 1000 mJ / cm 2 is more preferable. The light source used for exposure is not particularly limited, and any light source that emits light having a wavelength at which the photosensitizer in the photosensitive resin composition reacts (for example, g-line or i-line) may be used. Typically, a high-pressure mercury lamp is used. If necessary, post-exposure baking may be performed. The temperature of the post-exposure baking is not particularly limited, but is preferably 50 to 150 °C, more preferably 50 to 130 °C, still more preferably 55 to 120 °C, and even more preferably 60 to 110 °C. Also, the time of the post-exposure baking is preferably 1 to 30 minutes, more preferably 1 to 20 minutes, and still more preferably 1 to 15 minutes. In the exposure step, a photomask can be used. Thereby, a desired "pattern" can be formed using the photosensitive resin composition.

[0053] Examples of the developer in the development step include organic developers, water-soluble developers, etc. In the present embodiment, the developer preferably contains an organic solvent. More specifically, the developer is preferably a developer mainly composed of an organic solvent (a developer in which 95% by mass or more of the components are organic solvents). By developing with a developer containing an organic solvent, it becomes possible to suppress the swelling of the pattern by the developer more than when developing with an alkaline developer (aqueous system). That is, it is easier to obtain a finer pattern.

[0054] Specific examples of the organic solvent that can be used in the developer include ketone solvents such as cyclopentanone, ester solvents such as propylene glycol monomethyl ether acetate (PGMEA) and butyl acetate, ether solvents such as propylene glycol monomethyl ether, and the like. As the developer, an organic solvent developer consisting only of an organic solvent and containing no components other than unavoidably contained impurities may be used. Unavoidably contained impurities include metal elements and moisture, but there is no better situation than having few unavoidably contained impurities from the viewpoint of preventing contamination of electronic devices.

[0055] The method of bringing the developer into contact with the resin film is not particularly limited. Generally known methods such as the dipping method, paddle method, spray method, etc. can be appropriately applied.

[0056] The development time is appropriately adjusted based on, for example, the film thickness of the resin film and the shape of the pattern to be formed, and is in the range of, for example, 5 to 300 seconds, preferably 10 to 120 seconds.

[0057] The conditions of the thermosetting process are not particularly limited, but for example, the heating temperature can be 160 to 250 °C and the time can be 30 to 240 minutes.

[0058] The embodiments of the present invention have been described above, but these are examples of the present invention, and various configurations other than the above can be adopted. Further, the present invention is not limited to the above-described embodiments, and modifications, improvements, etc. within the scope capable of achieving the object of the present invention are included in the present invention.

Example

[0059] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereby.

[0060] <Synthesis of novolak-type phenol resin> [Example 1] Into a 3 L four-necked flask equipped with a stirrer, a thermometer, and a heat exchanger, 1000 parts by mass of bisphenol C, 300 parts by mass of ethylene glycol monomethyl ether, and 10 parts by mass of oxalic acid were charged, and the internal temperature of the four-necked flask was raised to 97 to 103 °C. Next, 475 parts by mass of a 37% aqueous formaldehyde solution was added over 1 hour while maintaining the internal temperature of the four-necked flask at 97 to 103 °C, and a reflux reaction was further carried out for 3 hours. Thereafter, dehydration was carried out under heating conditions of 200 °C for 4 hours under normal pressure conditions, and then unreacted monomers (phenols) were removed under heating conditions of 210 °C for 2 hours under a reduced pressure of -0.096 Mpa. As a result, 1050 parts by mass of novolak-type phenol resin 1 having a weight average molecular weight of 6000 was obtained. The molar ratio (B) / (A) of the structural unit (A) and the structural unit (B) of the obtained novolak-type phenol resin 1 was 1.50.

[0061] [Example 2] In a 3 L four-necked flask equipped with a stirrer, a thermometer, and a heat exchanger, 1000 parts by mass of bisphenol C, 300 parts by mass of ethylene glycol monomethyl ether, and 10 parts by mass of oxalic acid were charged, and the internal temperature of the four-necked flask was raised to 97 to 103 °C. Next, 602 parts by mass of a 37% aqueous formaldehyde solution was added over 90 minutes while maintaining the internal temperature of the four-necked flask at 97 to 103 °C, and a reflux reaction was further carried out for 3 hours. Then, dehydration was performed under heating conditions of 200 °C for 4 hours under normal pressure conditions, and subsequently, unreacted monomers (phenols) were removed under heating conditions of 210 °C for 2 hours under a reduced pressure of -0.096 Mpa. As a result, 1070 parts by mass of a novolak-type phenol resin 2 having a weight average molecular weight of 13000 was obtained. The molar ratio (B) / (A) of the structural unit (A) to the structural unit (B) of the obtained novolak-type phenol resin 2 was 1.90.

[0062] [Example 3] In a 3 L four-necked flask equipped with a stirrer, a thermometer, and a heat exchanger, 900 parts by mass of bisphenol C, 100 parts by mass of 2,5-xylenol, 300 parts by mass of ethylene glycol monomethyl ether, and 10 parts by mass of oxalic acid were charged, and the internal temperature of the four-necked flask was raised to 97 to 103 °C. Next, 646 parts by mass of a 37% aqueous formaldehyde solution was added over 90 minutes while maintaining the internal temperature of the four-necked flask at 97 to 103 °C, and a reflux reaction was further carried out for 3 hours. Then, dehydration was performed under heating conditions of 200 °C for 4 hours under normal pressure conditions, and subsequently, unreacted monomers (phenols) were removed under heating conditions of 210 °C for 2 hours under a reduced pressure of -0.096 Mpa. As a result, 1150 parts by mass of a novolak-type phenol resin 3 having a weight average molecular weight of 9000 was obtained. The molar ratio (B) / (A) of the structural unit (A) to the structural unit (B) of the obtained novolak-type phenol resin 3 was 1.75.

[0063] [Example 4] Into a 3 L four-necked flask equipped with a stirrer, a thermometer, and a heat exchanger, 700 parts by mass of bisphenol C, 300 parts by mass of 2,5-xylenol, 300 parts by mass of ethylene glycol monomethyl ether, and 10 parts by mass of oxalic acid were charged, and the internal temperature of the four-necked flask was raised to 97 - 103°C. Next, 774 parts by mass of a 37% aqueous formaldehyde solution was added over 90 minutes while maintaining the internal temperature of the four-necked flask at 97 - 103°C, and a reflux reaction was further carried out for 3 hours. Then, dehydration was carried out under heating conditions of 200°C for 4 hours under normal pressure conditions, and subsequently, unreacted monomers (phenols) were removed under heating conditions of 210°C for 2 hours under a reduced pressure of -0.096 Mpa. As a result, 1160 parts by mass of a novolak-type phenol resin 4 having a weight average molecular weight of 17000 was obtained. The molar ratio (B) / (A) of the structural unit (A) and the structural unit (B) of the obtained novolak-type phenol resin 4 was 1.75.

[0064] [Example 5] Into a 3 L four-necked flask equipped with a stirrer, a thermometer, and a heat exchanger, 500 parts by mass of bisphenol C, 500 parts by mass of 2,5-xylenol, 300 parts by mass of ethylene glycol monomethyl ether, and 10 parts by mass of oxalic acid were charged, and the internal temperature of the four-necked flask was raised to 97 - 103°C. Next, 775 parts by mass of a 37% aqueous formaldehyde solution was added over 90 minutes while maintaining the internal temperature of the four-necked flask at 97 - 103°C, and a reflux reaction was further carried out for 3 hours. Then, dehydration was carried out under heating conditions of 200°C for 4 hours under normal pressure conditions, and subsequently, unreacted monomers (phenols) were removed under heating conditions of 210°C for 2 hours under a reduced pressure of -0.096 Mpa. As a result, 1150 parts by mass of a novolak-type phenol resin 5 having a weight average molecular weight of 8500 was obtained. The molar ratio (B) / (A) of the structural unit (A) and the structural unit (B) of the obtained novolak-type phenol resin 5 was 1.50.

[0065] [Comparative Example 1] Into a 3 L four-necked flask equipped with a stirrer, a thermometer, and a heat exchanger, 1000 parts by mass of bisphenol C, 300 parts by mass of ethylene glycol monomethyl ether, and 10 parts by mass of oxalic acid were charged, and the internal temperature of the four-necked flask was raised to 97 to 103 °C. Next, 317 parts by mass of a 37% aqueous formaldehyde solution was added over 50 minutes while maintaining the internal temperature of the four-necked flask at 97 to 103 °C, and a reflux reaction was further carried out for 3 hours. Then, dehydration was carried out under heating conditions of 200 °C for 4 hours under normal pressure conditions, and subsequently, unreacted monomers (phenols) were removed under heating conditions of 210 °C for 2 hours under a reduced pressure of -0.096 Mpa. As a result, 1030 parts by mass of a novolak-type phenol resin 6 having a weight average molecular weight of 1600 was obtained. The molar ratio (B) / (A) of the structural unit (A) to the structural unit (B) of the obtained novolak-type phenol resin 6 was 1.00.

[0066] [Comparative Example 2] Into a 3 L four-necked flask equipped with a stirrer, a thermometer, and a heat exchanger, 1000 parts by mass of bisphenol C, 300 parts by mass of ethylene glycol monomethyl ether, and 10 parts by mass of oxalic acid were charged, and the internal temperature of the four-necked flask was raised to 97 to 103 °C. Next, 634 parts by mass of a 37% aqueous formaldehyde solution was added over 90 minutes while maintaining the internal temperature of the four-necked flask at 97 to 103 °C, and a reflux reaction was further carried out for 3 hours. Then, dehydration was carried out under heating conditions of 200 °C for 4 hours under normal pressure conditions, and subsequently, unreacted monomers (phenols) were removed under heating conditions of 210 °C for 2 hours under a reduced pressure of -0.096 Mpa. As a result, 1080 parts by mass of a novolak-type phenol resin 7 having a weight average molecular weight of 30000 was obtained. The molar ratio (B) / (A) of the structural unit (A) to the structural unit (B) of the obtained novolak-type phenol resin 7 was 2.00.

[0067] [Comparative Example 3] Instead of 1000 parts by mass of bisphenol C in Comparative Example 1, 500 parts by mass of m-cresol and 500 parts by mass of p-cresol were used, the amount of 37% aqueous formaldehyde solution was 451 parts by mass, and the conditions for removing unreacted monomers (phenols) were heating at 195 °C for 5 hours under a reduced pressure of -0.096 MPa. Otherwise, the same method as in Comparative Example 1 was used. As a result, 1050 parts by mass of a novolak-type phenol resin 8 with a weight average molecular weight of 4500 was obtained. The molar ratio (B) / (A) of the structural unit (A) to the structural unit (B) of the obtained novolak-type phenol resin 8 was 0.60.

[0068] <Preparation of Photosensitive Resin Composition> [Example 1] 20 parts by mass of novolak-type phenol resin 1 and 5 parts by mass of 2,3,4-trihydroxybenzophenone ester of naphthoquinone 1,2-diazide-5-sulfonic acid were dissolved in 75 parts by mass of propylene glycol monomethyl ether acetate (PGMEA). Then, it was filtered using a membrane filter with a pore size of 1.0 μm to prepare a photosensitive resin composition 1.

[0069] [Examples 2 to 5, Comparative Examples 1 to 3] Photosensitive resin compositions 2 to 8 were prepared in the same manner as in Example 1, except that the above novolak-type phenol resin 1 was changed to novolak-type phenol resins 2 to 8, respectively.

[0070] <Evaluation> For each physical property of the novolak-type phenol resins 1 to 8 and the photosensitive resin compositions 1 to 8 in each example and each comparative example, the following method was used for evaluation. The results are shown in Table 1.

[0071] [Evaluation of Novolak-Type Phenol Resins 1 to 8] (Weight Average Molecular Weight (Mw)) The polystyrene-equivalent weight average molecular weight (Mw) of the novolak-type phenol resins 1 to 8 in each example and each comparative example was measured by the GPC measurement method (gel permeation chromatography method) based on the following <GPC Measurement Conditions>. <GPC Measurement Conditions> The GPC device consists of a pump, an injector, a guard column, a column, and a detector. Tetrahydrofuran (THF) was used as the solvent for the measurement. The flow rate of the pump was set at 0.5 ml / min. A commercially available guard column (TSK GUARDCOLUMN HR-L manufactured by Tosoh Corporation: diameter 6.0 mm, column length 40 mm) was used for the guard column, and multiple commercially available polystyrene gel columns (TSK-GEL GMHHR-L manufactured by Tosoh Corporation: diameter 7.8 mm, column length 30 mm) were connected in series for the column. A differential refractometer (RI detector, Waters differential refractometer (RI) detector W2414) was used for the detector. For the samples, THF solutions of novolak-type phenol resins 1 to 8 adjusted to a concentration of 3 to 4 mg / ml were prepared respectively, and about 50 to 150 μl of each solution was injected from an injector for measurement. For the analysis of the samples, a calibration curve prepared with a monodisperse polystyrene standard sample was used.

[0072] (Alkali dissolution rate) The alkali dissolution rates of novolak-type phenol resins 1 to 8 in each example and each comparative example were measured by the following (Method 1). (Method 1) The novolak-type phenol resins in each example and each comparative example were prepared as a 25 mass% propylene glycol monomethyl ether acetate solution. This solution was applied onto a silicon wafer with a spin coater to a thickness H of 1 μm, and dried on a hot plate at 110°C for 90 seconds. Then, the novolak-type phenol resin applied on the silicon wafer was dissolved with a developer (2.38% aqueous solution of tetramethylammonium hydroxide), and the time T for the novolak-type phenol resin to dissolve was visually measured. Then, the alkali dissolution rate [Å / sec] was calculated from the following formula. (Alkali dissolution rate)[Å / sec] = (thickness H) / (time T for the novolak-type phenol resin to dissolve)

[0073] (Total content of phenols and cresols (GC-MS)) The total content of phenols and cresols in novolak-type phenolic resins 1 to 8 of each example and each comparative example was measured by the following (Method 2). (Method 2) Using GC-MS (gas chromatography mass spectrometer), 1 μL of the novolak-type phenolic resin of each example and each comparative example was directly introduced into the injection port of the GC-MS to measure the mass spectrum of the novolak-type phenolic resin. Then, based on the calibration curve prepared using phenols and cresols with known concentrations, the total content [ppm] of phenols and cresols was calculated from the area ratio. The conditions of the GC-MS at this time are as follows. Extraction solvent: Normal hexane GC injection port temperature: 250 °C GC oven temperature: Held at 40 °C for 5 minutes and then heated to 300 °C and held for 9 minutes MS interface temperature: 300 °C Chromatograph: Agilent 6890N (manufactured by Agilent Technologies) Mass detector: Agilent 5975B (manufactured by Agilent Technologies) Analysis column: HP-5MS (manufactured by Agilent Technologies)

[0074] [Evaluation of photosensitive resin compositions 1 to 8] (Residual film ratio) The photosensitive resin compositions 1 to 8 of each example and each comparative example were each applied onto a 3-inch diameter silicon wafer to a thickness of 1 μm using a spin coater and dried on a hot plate at 110 °C for 100 seconds to form a photosensitive resin film. The above photosensitive resin film was immersed in a developer (2.38 mass% aqueous solution of tetramethylammonium hydroxide) for 60 seconds without exposure. It was evaluated by the residual film ratio (film thickness after development / initial film thickness) [%] before and after immersion.

[0075] (Alkali dissolution rate · Contrast) The photosensitive resin compositions 1 to 8 of each example and each comparative example were each applied onto a 3-inch diameter silicon wafer with a spin coater so as to have a thickness H of 1 μm, and dried on a hot plate at 110°C for 90 seconds. Two wafers were prepared for each, and one was used as an unexposed sample. The other was used as an exposed sample and irradiated with g, h, and i rays having a total irradiation dose of 100 mJ / cm 2 using a g, h, and i ray lamp ("Mercury Lamp Lighting Power Supply" manufactured byUSHIO INC.). For both the unexposed sample and the exposed sample, a developer (2.38% aqueous solution of tetramethylammonium hydroxide) was used to dissolve the photosensitive resin composition of each sample, and the time T for the photosensitive resin composition to dissolve was visually measured. Thereafter, the alkali dissolution rate of the unexposed sample and the alkali dissolution rate [Å / sec] of the exposed sample were calculated from the following equations, respectively. (Alkali dissolution rate) [Å / sec] = (Thickness H) / (Time T for the photosensitive resin composition to dissolve) Thereafter, the ratio of the alkali dissolution rates of the unexposed sample and the exposed sample (alkali dissolution rate of the exposed sample / alkali dissolution rate of the unexposed sample) was evaluated as the contrast.

[0076] (Resolution) The photosensitive resin compositions 1 to 8 of each example and each comparative example were each applied onto a 3-inch diameter silicon wafer with a spin coater, and pre-baked on a hot plate at 110°C for 100 seconds to form a resist film with a film thickness of 1.5 μm. Through a pattern mask with a line width of 100 μm to 1 μm engraved on the resist film, ultraviolet rays of 5 mJ / cm 2 were used for exposure for 40 seconds. After exposure, development was immediately carried out at 23°C for 60 seconds with a 2.38 wt% aqueous solution of tetramethylammonium hydroxide, followed by washing with water and drying to obtain a positive pattern. At that time, the dimension of the smallest photoresist pattern that was resolved was defined as the limit resolution. The limit resolution was evaluated according to the following criteria. A: The limit resolution is 5 μm or less. B: The limit resolution exceeds 5 μm and is 10 μm or less. C: The limit resolution exceeds 10 μm.

[0077] (Heat resistance) The photosensitive resin compositions 1 to 8 of each example and each comparative example were each applied onto a 3-inch diameter silicon wafer treated with hexamethyldisilazane using a spin coater so that the thickness at the time of drying became 1.5 μm, and dried on a hot plate at 110 °C for 90 seconds. Thereafter, using a reduction projection exposure apparatus, exposure was performed through a test chart mask, and development was performed for 50 seconds using a developer (2.38% aqueous solution of tetramethylammonium hydroxide). Heat treatment was performed on the obtained developed silicon wafer under the conditions of 140 °C for 3 minutes. Before and after the heat treatment, the shape of the resist pattern on the silicon wafer was observed with a scanning electron microscope. The evaluation criteria for the resist pattern shape are as follows. A: No change in the pattern shape is observed. B: Slight deformation is seen at the corners of the pattern. C: A change in the pattern shape is observed.

[0078]

Table 1

[0079] Each example containing a structural unit (A) containing a structural unit (A1) derived from bisphenols and a structural unit (B) derived from aldehydes, and having a molar ratio (B) / (A) of the structural unit (A) and the structural unit (B) of 1.30 or more and less than 2.00 was shown to have an improved performance balance between developability and heat resistance as compared with each comparative example.

Claims

1. A structural unit (A) containing a structural unit (A1) derived from bisphenols, a structural unit (B) derived from aldehydes, and, a novolak-type phenol resin, wherein the molar ratio (B) / (A) of the structural unit (A) to the structural unit (B) is 1.30 or more and less than 2.

00.

2. The novolak-type phenol resin according to claim 1, wherein the structural unit (A) further contains a structural unit (A2) derived from xylenols.

3. The novolak-type phenol resin according to claim 2, wherein the content of the structural unit (A1) is 10 mol% or more and 99 mol% or less when the total content of the structural unit (A) is 100 mol%.

4. The novolak-type phenol resin according to claim 2 or 3, wherein the content of the structural unit (A2) is 1 mol% or more and 90 mol% or less when the total content of the structural unit (A) is 100 mol%.

5. The novolak-type phenol resin according to claim 2 or 3, wherein the xylenols contain one or more selected from the group consisting of 2,5-xylenol, 2,4-xylenol, and 3,5-xylenol.

6. The novolak-type phenol resin according to claim 1 or 2, wherein the bisphenols contain one or more selected from the group consisting of bisphenol C, bisphenol A, and bisphenol F.

7. The novolak-type phenol resin according to claim 1 or 2, wherein the content of the structural unit (A) is 5 mol% or more and 45 mol% or less when the total structural units constituting the novolak-type phenol resin is 100 mol%.

8. The novolak-type phenol resin according to claim 1 or 2, wherein the aldehydes contain one or more selected from the group consisting of formaldehyde, paraformaldehyde, acetaldehyde, and salicylaldehyde.

9. The novolak-type phenol resin according to claim 1 or 2, wherein the mass average molecular weight in terms of polystyrene of the novolak-type phenol resin is 1000 or more and 100000 or less.

10. The novolak-type phenol resin according to claim 1 or 2, wherein the alkali dissolution rate of the novolak-type phenol resin by the following (Method 1) is 1 Å / second or more and 4000 Å / second or less. (Method 1) The novolak-type phenol resin is prepared as a 25% by mass propylene glycol monomethyl ether acetate solution. This solution is applied onto a silicon wafer with a spin coater to a thickness H of 1 μm and dried on a hot plate at 110 °C for 90 seconds. Then, the novolak-type phenol resin applied to the silicon wafer is dissolved with a developer (2.38% aqueous tetramethylammonium hydroxide solution), and the time T for the novolak-type phenol resin to dissolve is visually measured. Then, the alkali dissolution rate is calculated from the following formula. (Alkali dissolution rate) [Å / sec] = (Thickness H) / (Time T for the novolak-type phenol resin to dissolve)

11. The novolak-type phenol resin according to claim 1 or 2, wherein the total content of phenols and cresols calculated from the area ratio by the following (Method 2) is 500 ppm or less. (Method 2) Using GC-MS (gas chromatography mass spectrometer), 1 μL of the novolak-type phenol resin is directly introduced into the injection port of the GC-MS to measure the mass spectrum of the novolak-type phenol resin. Then, based on the calibration curve prepared using phenols and cresols with known concentrations, the total content of phenols and cresols is calculated from the area ratio.

12. A photosensitive resin composition comprising the novolak-type phenol resin according to claim 1 or 2, a photosensitizer, and a solvent.

13. The photosensitive resin composition according to claim 12, wherein the content of the novolak-type phenol resin is 10% by mass or more and 40% by mass or less when the total components of the photosensitive resin composition are 100% by mass.

14. The photosensitive resin composition according to claim 12, wherein the photosensitizer contains one or more selected from the group consisting of polyhydroxybenzophenones, bis[(poly)hydroxyphenyl]alkanes, tris(hydroxyphenyl)methanes or their methyl-substituted products, and bis(cyclohexylhydroxyphenyl)(hydroxyphenyl)methanes or their methyl-substituted products.

15. The photosensitive resin composition according to claim 12, wherein the content of the photosensitizer is 1% by mass or more and 10% by mass or less when the total components of the photosensitive resin composition are 100% by mass.

16. The photosensitive resin composition according to claim 12, wherein the solvent contains one or more selected from the group consisting of ethylene glycol alkyl ethers, diethylene glycol dialkyl ethers, ethylene glycol alkyl ether acetates, propylene glycol alkyl ether acetates, ketones, cyclic ethers and esters.

17. The photosensitive resin composition according to claim 12, wherein the content of the solvent is 50% by mass or more and 90% by mass or less when the total components of the photosensitive resin composition are 100% by mass.

18. The photosensitive resin composition according to claim 12, which can be used for a photoresist.

19. A resin film containing a cured product of the photosensitive resin composition according to claim 12.

20. An electronic device including the resin film according to claim 19.

Images