Branched organopolysiloxane, composition containing same and use thereof

Abstract

The purpose of the present invention is to provide a novel material which exhibits good alkali solubility by irradiation with high energy rays and can be used as a resist material. The novel material of the present invention is a branched organopolysiloxane represented by average unit formula (1), and having a weight-average molecular weight of 2,000 or less, a polydispersity of 1.30 or less, and a hydrophilic group protected by an acid-decomposable functional group in a molecule thereof. Formula (1): (R3SiO1 / 2)a(R2SiO2 / 2)b(RSiO3 / 2)c(SiO4 / 2)d(O1 / 2Z)e In the formula, R is a group selected from a monovalent hydrocarbon group or the like and a hydrophilic group protected by an acid-decomposable functional group, and a, b, c, d, and e are numbers satisfying the following conditions: 0 ≤ a; 0 ≤ b; 0.8 ≤ c; 0 ≤ d; 0 ≤ e; and a + b + c + d = 1.

Description

Branched organopolysiloxane, composition containing same and use thereof

[0001] The present invention relates to a branched organopolysiloxane whose solubility in an aqueous alkaline solution is improved by irradiation with high-energy radiation such as ultraviolet radiation (including extreme ultraviolet radiation and far ultraviolet radiation) or an electron beam, and to a composition containing the same. The branched organopolysiloxane of the present invention has a low molecular weight and a narrow molecular weight distribution, and forms a coating film with good alkali solubility by irradiation with high-energy radiation. Therefore, the branched organopolysiloxane of the present invention exhibits excellent lithography performance and is suitable as a resist material and as an insulating material, particularly a coating material, for electronic and electrical devices that require patterning.

[0002] Silicone resins have high heat resistance and excellent chemical stability, and therefore have been used conventionally as coating agents, potting agents, insulating materials, etc. for electronic and electrical devices.

[0003] Touch panels are used in a variety of display devices, such as mobile devices, industrial equipment, and car navigation systems. To improve the detection sensitivity of touch panels, it is necessary to suppress electrical influences from light-emitting elements, such as light-emitting diodes (LEDs) and organic light-emitting diode (OLED) devices. Therefore, an insulating layer is typically disposed between the touch panel and the light-emitting elements. Meanwhile, thin display devices, such as OLEDs, have a structure in which many functional thin layers are stacked. In recent years, studies have been conducted to improve the visibility of display devices by stacking insulating layers formed from high-refractive-index acrylate polymers and polyfunctional polymerizable monomers above and below the touch panel layer (see, for example, Patent Documents 1 and 2).

[0004] Photolithography technology has made it possible to miniaturize patterns in the manufacture of semiconductor devices, and has made remarkable progress in recent years. Silicone-based resist materials have also long been studied in the field of photolithography technology, taking advantage of their excellent etching resistance. Specifically, silicone resins whose solubility in developing solutions increases or decreases upon exposure to high-energy rays, and compositions containing such silicone resins, have been reported. In pursuit of improved pattern accuracy, so-called chemically amplified resist materials, whose solubility in developing solutions increases upon exposure to high-energy rays, are considered advantageous.

[0005] Patent Document 3 discloses a chemically amplified resist material comprising silsesquioxane units having silicon-bonded hydrogen, silsesquioxane units having a carboxyl group protected by an acid-dissociable group, and other silsesquioxane units. Because this material exhibits a medium to high molecular weight, there are issues with the linewidth uniformity of the resulting pattern. Patent Document 4 discloses a silicon-based resist underlayer film-forming composition containing silsesquioxane units containing a carboxylic acid ester group. Resist underlayer films obtained from this composition do not exhibit alkali solubility due to a low concentration of hydrophilic functional groups. Furthermore, Patent Document 5 discloses an antireflective material containing a silicon-based polymer to which a cage-type oligosilsesquioxane having a hydrophilic side chain protected by an acid-labile functional group has been added, and a photoacid generator. The cage-type oligosilsesquioxane used here is used in small amounts, and contains high molecular weight compounds of dimers or higher, making its use in resist materials problematic.

[0006] That is, none of the above documents discloses a branched organopolysiloxane composition having a structure that exhibits high solubility in an alkaline aqueous solution upon irradiation with high-energy rays.

[0007] JP 2013-140229 A JP 2021-61056 A JP 2007-182555 A Japanese Patent No. 6436301 A Japanese Patent No. 6197883 A

[0008] Under the above circumstances, an object of the present invention is to provide a novel material that exhibits good alkali solubility upon irradiation with high-energy rays and can be used as a resist material, a composition containing the same, and uses thereof.

[0009] The present invention was made to solve the above-mentioned problems. It was discovered that a branched organopolysiloxane having a hydrophilic group protected by an acid-decomposable functional group bonded to a silicon atom in the molecule, containing silsesquioxane units (so-called T units) as its main constituent units, and having a weight-average molecular weight and polydispersity index each below a predetermined value, exhibits high solubility in an aqueous alkaline developer solution upon exposure to high-energy radiation and is useful as a resist material. Furthermore, the branched organopolysiloxane can form a coating film that is highly transparent and has sufficient mechanical strength for practical use. Furthermore, the branched organopolysiloxane preferably has a relatively small molecular weight and a low polydispersity index, and from the standpoint of technical effect, it is particularly preferred that the branched organopolysiloxane have a cage molecular structure, including a complete cage structure.

[0010] In one embodiment of the present invention, a composition containing the above-mentioned branched organopolysiloxane (referred to herein as a "branched organopolysiloxane composition" or "composition") undergoes a chemical reaction upon irradiation with high-energy rays such as ultraviolet light, thereby controlling the solubility in an alkaline aqueous solution. In other embodiments of the present invention, any means capable of initiating a chemical reaction may be employed in addition to or instead of the high-energy ray irradiation.

[0011] More specifically, the branched organopolysiloxane of the present invention is represented by the following average unit formula (1), and has a weight average molecular weight of 2,000 or less and a polystyrene equivalent, as measured by gel permeation chromatography, of 1.30 or less. (R ３ SiO １／２ ) ａ (R ２ SiO ２／２ ) ｂ (RSiO ３／２ ) ｃ (SiO ４／２ )ｄ (O １／２ Z) ｅ (1) In the above formula (1), each R is independently a group selected from the group consisting of unsubstituted or fluorine-substituted monovalent hydrocarbon groups, alkoxy groups, hydroxyl groups, and hydrophilic groups protected with an acid-decomposable functional group. Z is a hydrogen atom or an alkyl group. a, b, c, d, and e are numbers that satisfy the following conditions: 0≦a, 0≦b, 0.8≦c, 0≦d, 0≦e, and a+b+c+d=1. The branched organopolysiloxane represented by the above formula (1) must have at least one hydrophilic group protected with an acid-decomposable functional group in the molecule.

[0012] The composition of the present invention contains the branched organopolysiloxane (sometimes referred to as "component (A)" in this specification) as well as the following components (B) and (C): (B) a photoacid generator in an amount of 0.1 parts by mass or more and 20 parts by mass or less per 100 parts by mass of component (A); and (C) an organic solvent.

[0013] In the formula (1) of the component (A) described above, a may be 0, b may be 0, and d may be 0.

[0014] In the above-mentioned component (A), the number of siloxane units having a hydrophilic group protected with an acid-decomposable functional group may be more than 20 mol % of the total number of siloxane units.

[0015] In the above-mentioned component (A), the hydrophilic group protected by the acid-decomposable functional group may be a group represented by the following formula (2): *-R １ -O-R ２ (2) In the above formula (2), R １ R is a divalent hydrocarbon group which may have a carbonyl group. ２ is a monovalent hydrocarbon group or trialkylsilyl group having 1 to 4 carbon atoms, and * is the bonding site to a silicon atom on the organopolysiloxane.

[0016] In the formula (2) of the component (A), the R ２ may be a tert-butyl group.

[0017] In the above-mentioned component (A), the hydrophilic group protected by the acid-decomposable functional group may be a group represented by the following formula (2-A): ３ -CO ２ -R ４ (2-A) In the above formula (2-A), R ３ is a divalent hydrocarbon group having 2 to 6 carbon atoms. ４ is a monovalent hydrocarbon group or trialkylsilyl group having 1 to 4 carbon atoms, and * is the bonding site to a silicon atom on the organopolysiloxane.

[0018] In the formula (2-A) of the component (A), the R ４ may be a tert-butyl group.

[0019] In the above-mentioned component (A), the hydrophilic group protected with the acid-decomposable functional group may be a phenol ether group represented by the following formula (2-B): In the above formula (2-B), R ５ is a monovalent branched saturated hydrocarbon group or trialkylsilyl group having 3 to 4 carbon atoms, and * is the bonding site to a silicon atom on the organopolysiloxane.

[0020] In the formula (2-B) of the component (A), the R ５ may be a tert-butyl group.

[0021] The weight-average molecular weight of the component (A) may be 1,500 or less. The component (A) may have a cage molecular structure. The polydispersity of the component (A) may be 1.20 or less.

[0022] The above-described component (A) may contain an unsubstituted or fluorine-substituted monovalent hydrocarbon group as the substituent R. The substituent R may be a monovalent hydrocarbon group having from 1 to 3 carbon atoms. The substituent R may also be a phenyl group.

[0023] In the formula (1) of the component (A) described above, e may satisfy the relationship 0≦e≦0.05.

[0024] The average number of silicon atoms per molecule of the above-mentioned component (A) may be 12 or less.

[0025] The branched organopolysiloxane composition of the present invention was applied to a glass plate so that the thickness after application was 0.5 μm, and then heat-treated at 100° C. for 1 minute to prepare a coating film containing no organic solvent. The coating film was then irradiated with high-energy rays containing light with a wavelength of 254 nm at a dose of 40 mJ / cm in terms of the amount of light at 254 nm. ２ and then heat-treating (post-exposure baking, PEB) at 120°C for 2 minutes, and immersing the resulting light-irradiated coating film in a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (TMAH) for 1 minute and then rinsing with water, the composition may be such that the rate of mass reduction of the coating film made of the branched organopolysiloxane is 90 mass% or more.

[0026] The present invention provides an insulating coating agent containing the above-mentioned branched organopolysiloxane composition.The present invention also provides a resist material containing the above-mentioned branched organopolysiloxane composition.

[0027] The present invention provides a method for using the branched organopolysiloxane composition described above as an insulating coating layer.

[0028] The present invention further provides a display device, such as a liquid crystal display, an organic EL display, or an organic EL flexible display, which comprises a layer made of the branched organopolysiloxane composition described above.

[0029] The present invention provides a branched organopolysiloxane that exhibits good alkali solubility upon irradiation with high-energy radiation and can be used as a resist material, a composition containing the same, and uses thereof. More specifically, high-energy radiation irradiation causes a deprotection reaction of the hydrophilic groups protected by acid-decomposable functional groups in the branched organopolysiloxane of the present invention. Therefore, high-energy radiation irradiation enhances the solubility of a coating film made from a composition containing the branched organopolysiloxane in an aqueous alkaline solution. Furthermore, the branched organopolysiloxane of the present invention has a low weight-average molecular weight and low polydispersity, enabling high-precision patterning through a simple process in the lithography process used to form a desired pattern. Furthermore, the branched organopolysiloxane composition of the present invention has good coatability on various substrates. Furthermore, coating films formed from the composition of the present invention have the advantage of being optically transparent and allowing for a wide range of hardness and other properties to be designed. Therefore, the composition of the present invention is useful as a resist material that utilizes a wide range of light sources, particularly short-wavelength light sources. The composition of the present invention is also useful as a material for an insulating layer for electronic devices, particularly thin display devices such as OLEDs, and particularly as a patterning material or coating material.

[0030] The configuration of the present invention will be described in more detail below. The branched organopolysiloxane of the present invention is an organopolysiloxane having a specific structure and containing hydrophilic groups protected by acid-decomposable functional groups. The branched organopolysiloxane composition of the present invention essentially comprises component (A), a branched organopolysiloxane having the specific structure, (B) a photoacid generator, and (C) an organic solvent. Component (A) in the composition of the present invention contains at least one hydrophilic group protected by an acid-decomposable functional group and is converted by irradiation with high-energy rays into an organopolysiloxane having good solubility in aqueous alkaline solutions (sometimes referred to as "alkali-soluble" in this specification).

[0031] Here, alkaline aqueous solutions used as developers include well-known basic aqueous solutions such as sodium hydroxide (NaOH), potassium hydroxide (KOH), and quaternary ammonium salts. Among these, KOH aqueous solutions and tetramethylammonium hydroxide (TMAH) aqueous solutions are commonly used, with TMAH aqueous solutions being particularly widely used. Therefore, in this specification, "alkali-soluble" means soluble in TMAH aqueous solutions. It should be noted that the alkaline aqueous solution used as a developer when forming a pattern using the composition of the present invention is not limited to a TMAH solution.

[0032] In one embodiment of the present invention, whether a branched organopolysiloxane that has been irradiated with high-energy rays is "alkali-soluble" can be confirmed by the following method: A test mixture containing the branched organopolysiloxane of the present invention and an organic solvent is applied to a glass plate to a thickness of 0.5 μm, and a coating film containing no organic solvent is prepared by heat treatment at 100° C. for 1 minute. The coating film is then irradiated with high-energy rays containing light with a wavelength of 254 nm at a dose of 40 mJ / cm, calculated as the light intensity at 254 nm. ２ After irradiating the composition so that the temperature is 100°C, a heat treatment (post-exposure bake, PEB) is performed at 120°C for 2 minutes. When the resulting irradiated coating film is immersed in a 2.38% by mass aqueous solution of TMAH for 1 minute and then washed with water, if the mass loss rate of the coating film made of the organopolysiloxane is 90% by mass or more, it can be determined that the branched organopolysiloxane has exhibited sufficiently excellent alkali solubility due to irradiation with high-energy rays. In particular, if the mass loss rate of the coating film made of the branched organopolysiloxane when evaluated by the above method is 95% by mass or more or 98% by mass or more, it can be said to have very excellent alkali solubility. Note that spin coating or the like is commonly used to apply a composition containing a branched organopolysiloxane to a glass plate, and the organic solvent must then be removed by drying or the like. In the water washing step, the substrate is generally washed for about 10 to 15 seconds by immersion in a water bath at about room temperature (25°C) or in running water at a flow rate similar to that of household tap water, so as not to adversely affect the formed pattern or the substrate.

[0033] In the above-described method for evaluating alkali solubility, by replacing the "test mixture" with the "branched organopolysiloxane composition," it is possible to evaluate the alkali solubility of a coating film made of the branched organopolysiloxane composition.

[0034] Because the branched organopolysiloxane of the present invention has a low weight-average molecular weight and a small polydispersity, it tends to have improved alkali solubility after high-energy radiation irradiation compared to medium- to high-molecular-weight organopolysiloxanes similarly composed of silsesquioxane units. When the alkali solubility of a coating film composed of a branched organopolysiloxane is evaluated using the alkali solubility evaluation method described above, it is particularly preferable that the mass loss rate of the resulting coating film after high-energy radiation irradiation is 98% by mass or more. A mass loss rate of 98% by mass or more can be said to indicate that a branched organopolysiloxane with particularly excellent alkali solubility and a coating film composed thereof have been obtained.

[0035] <Component (A): Branched Organopolysiloxane> The branched organopolysiloxane, which is component (A) of the present invention, is represented by the following average unit formula (1): (R ３ SiO １／２ ) ａ (R ２ SiO ２／２ ) ｂ (RSiO ３／２ ) ｃ (SiO ４／２ ) ｄ (O １／２ Z) ｅ (1)

[0036] In the above formula (1), R is each independently a group selected from the group consisting of unsubstituted or fluorine-substituted monovalent hydrocarbon groups, alkoxy groups, hydroxyl groups, and hydrophilic groups protected with an acid-decomposable functional group. Z is a hydrogen atom or an alkyl group. a, b, c, d, and e are numbers that satisfy the following conditions: 0≦a, 0≦b, 0.8≦c, 0≦d, 0≦e, and a+b+c+d=1. In other words, a, b, c, and d represent the ratio (based on the amount of substance) of the number of each siloxane unit to the total number of siloxane units, assuming that the total number of siloxane units contained in the branched organopolysiloxane is 1. Furthermore, e is the ratio (based on the amount of substance) of the number of all siloxane units to the total number of siloxane units, assuming that the total number of all siloxane units is 1. １／２ Z) (based on the amount of substance). The branched organopolysiloxane represented by the average unit formula (1) has at least one hydrophilic group protected by an acid-decomposable functional group in the molecule. The four siloxane units described in the average unit formula (1) below may each be of one type or of two or more types. That is, component (A) can be, for example, (RSiO ３／２ The siloxane unit may contain only one type of siloxane unit corresponding to the above formula (1), or may contain two or more types of siloxane units corresponding to the above formula (1).

[0037] In the branched organopolysiloxane represented by the above average unit formula (1), there is a degree of freedom in the ratio of each constituent unit, but the constituent ratio of monoorganosiloxy units (also called "T units" or "silsesquioxane units") to all siloxane units satisfies the above-mentioned formula: 0.8≦c. Considering that the desirable properties of the branched organopolysiloxane are a solid with no surface tack and a small polydispersity, monoorganosiloxy units must be the main constituent units.

[0038] The molecular weight of component (A) of the present invention must be 2,000 or less as a weight-average molecular weight converted to standard polystyrene, as measured by gel permeation chromatography (hereinafter sometimes referred to as the "GPC method"). This characteristic makes it easy to design a material that exhibits excellent alkali solubility after high-energy radiation irradiation and enables high-precision patterning. The weight-average molecular weight (Mw) of component (A) is preferably 1,800 or less, or 1,500 or less, and more preferably in the range of 1,000 to 1,800, 1,000 to 1,600, 1,000 to 1,500, or 1,000 to 1,200.

[0039] On the other hand, the polydispersity index (hereinafter sometimes referred to as "PDI") of component (A) of the present invention is a value defined as the value of "Mw / Mn" using the number average molecular weight (Mn) and weight average molecular weight (Mw) determined by GPC in terms of standard polystyrene. A smaller polydispersity index indicates a narrower and sharper molecular weight distribution. Specifically, the polydispersity index of component (A) must be 1.30 or less. This characteristic enables high-precision patterning using component (A) of the present invention and the composition of the present invention containing it, and particularly reduces non-uniformity in line width. The polydispersity index of component (A) of the present invention is preferably 1.20 or less, and particularly preferably in the range of 1.00 to 1.30, and particularly preferably in the range of 1.00 to 1.15.

[0040] As described above, it is essential that the component (A) of the present invention has a weight-average molecular weight of 2,000 or less and a polydispersity of 1.30 or less. If the weight-average molecular weight or polydispersity exceeds the respective upper limits, the composition of the present invention may lose either or both of its alkali solubility after high-energy radiation irradiation and its high-precision patterning ability (including coatability). Such a composition cannot be suitably used as a patterning material.

[0041] The average number of silicon atoms per molecule in the branched organopolysiloxane, component (A) of the present invention, is preferably 12 or less. That is, the branched organopolysiloxane of the present invention may be a branched organopolysiloxane having a single number of silicon atoms, or may be a mixture of two or more branched organopolysiloxanes having different numbers of silicon atoms. However, it is preferred that the average number of silicon atoms in all molecules of such branched organopolysiloxanes be 12 or less. In the branched organopolysiloxane of the present invention, the average number of silicon atoms per molecule is preferably 10 or less, more preferably 8 or less. The average number of silicon atoms per molecule is preferably in the range of 4 to 8, particularly preferably 5 to 8. This characteristic also affects the feasibility of high-precision patterning. In the branched organopolysiloxane of the present invention, a small average number of silicon atoms is preferred, and a small deviation is also preferred.

[0042] The branched organopolysiloxane, component (A) of the present invention, preferably has a cage molecular structure. A cage molecular structure refers to a so-called polyhedral cluster structure or a structure similar thereto. Branched organopolysiloxanes with a cage molecular structure are also called polyhedral oligomeric silsesquioxanes, and these compounds have a symmetrical molecular structure or a molecular structure similar thereto. Well-known polyhedral oligomeric silsesquioxanes include those with a regular hexahedron structure containing 8 silicon atoms, a pentagonal prism structure containing 10 silicon atoms, and a heptahedron structure containing 12 silicon atoms.

[0043] The component (A) of the present invention is a compound represented by the formula (1) (RSiO ３／２ ) ｃIt is particularly preferred that the branched organopolysiloxane of the present invention be a branched organopolysiloxane having a cage molecular structure in which the main structural unit is a silsesquioxane unit, i.e., a silsesquioxane unit. As mentioned above, c satisfies the condition 0.8≦c, and naturally also satisfies the condition 0.8≦c≦1.0. In particular, it is preferred that the above-mentioned a, b, and d are 0. Furthermore, as will be described later, from the viewpoint of providing a complete cage molecular structure, e may and is preferred to be 0. That is, the branched organopolysiloxane of the present invention represented by the above formula (1) is (RSiO ３／２ ) ｃ It is particularly preferred that the organopolysiloxane is a branched organosiloxane having a cage structure consisting only of silsesquioxane units. ３／２ ) ｃ It goes without saying that the number of silicon atoms originating from a unit corresponds to the number of silicon atoms in the molecule.

[0044] In one embodiment of the present invention, (O １／２ Z) ｅ The unit is (RSiO ３／２ ) ｃ unit as the main structural unit, and optionally (R ２ SiO ２／２ ) ｂ Units and (SiO ４／２ ) ｄ Z represents the Si—OH and / or Si—O-alkyl groups that remain after a partial incomplete condensation reaction when a branched organopolysiloxane having a cage molecular structure that may contain a unit is formed. That is, each Z is independently a hydrogen atom or an alkyl group. Specific examples of the alkyl group constituting Z include alkyl groups having 1 to 20 carbon atoms. The alkyl group having 1 to 20 carbon atoms is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably a methyl group, an ethyl group, or an isopropyl group.

[0045] When all of the condensation reactive groups in the branched organopolysiloxane of formula (1) are bonded to one another to form Si—O—Si bonds, e is 0 (zero) in formula (1). This is called a complete cage structure. When e is not 0, not all of the condensation reactive groups in the branched organopolysiloxane of formula (1) are bonded to one another to form Si—O—Si bonds, with some forming SiOZ. This is called a partially cleaved structure. Thus, both complete cage structures and partially cleaved structures are known as cage molecular structures for branched organopolysiloxanes, and either can be used as the branched organopolysiloxane that is component (A) of the present invention. However, it is preferable that component (A) of the present invention be a complete cage structure (i.e., e = 0 in formula (1)) or a structure close to it. For example, e is preferably 15% or less (e≦0.15), more preferably 10% or less (e≦0.1), and even more preferably 5% or less (e≦0.05) relative to a+b+c+d, and a complete cage structure is particularly preferred. Specific examples of complete cage structures and partially cleaved structures of branched organopolysiloxanes are shown, for example, in paragraphs

[0047] to

[0049] of JP-A No. 2010-515778.

[0046] The branched polyorganosiloxane of the present invention represented by the average unit formula (1) is characterized in that it contains, in its molecule, at least one hydrophilic group protected by an acid-decomposable functional group. The hydrophilicity of the functional group is suppressed by the protecting group before irradiation with high-energy rays. However, irradiation with high-energy rays causes a deprotection reaction of the hydrophilic group, resulting in the development of hydrophilicity derived from the functional group after irradiation with high-energy rays, and the solubility of the coating film made of the branched polyorganosiloxane in an alkaline aqueous solution is increased.

[0047] In one embodiment of the present invention, the substituents R in the branched polyorganosiloxane represented by the average unit formula (1) may all be hydrophilic groups protected with acid-decomposable functional groups. On the other hand, the substituents R other than the hydrophilic groups protected with acid-decomposable functional groups in the average unit formula (1) are groups selected from unsubstituted or fluorine-substituted monovalent hydrocarbon groups, alkoxy groups, and hydroxyl groups. From the viewpoint of controlling the surface tack of the coating film after removing the organic solvent, it is preferable that the branched polyorganosiloxane has these groups (i.e., at least one group selected from the group consisting of unsubstituted or fluorine-substituted monovalent hydrocarbon groups, alkoxy groups, and hydroxyl groups).

[0048] Preferred examples of the unsubstituted or fluorine-substituted monovalent hydrocarbon group that can constitute the substituent R include unsubstituted alkyl, cycloalkyl, alkenyl, arylalkyl, and aryl groups having from 1 to 20 carbon atoms, and monovalent organic groups in which at least a portion of the hydrogen atoms of these groups have been substituted with fluorine. In one embodiment of the present invention, the unsubstituted monovalent hydrocarbon group that can constitute the substituent R is preferably a monovalent hydrocarbon group having from 1 to 3 carbon atoms.

[0049] Examples of unsubstituted alkyl groups having 1 to 20 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, pentyl, hexyl, and octyl groups. Of these, methyl and hexyl groups are particularly preferred. Examples of unsubstituted cycloalkyl groups having 1 to 20 carbon atoms include cyclopentyl and cyclohexyl groups. Examples of unsubstituted alkenyl groups having 1 to 20 carbon atoms include vinyl, allyl, 1-butenyl, and 1-hexenyl groups. Of these, vinyl and hexenyl groups are particularly preferred. Examples of unsubstituted arylalkyl groups having 1 to 20 carbon atoms include benzyl and phenylethyl groups. Examples of unsubstituted aryl groups having 1 to 20 carbon atoms include phenyl and naphthyl groups. Of these, phenyl groups are particularly preferred. Examples of the fluorine-substituted monovalent hydrocarbon group include 3,3,3-trifluoropropyl, 3,3,4,4,5,5,6,6,6-nonafluorohexyl, etc. Among these, the 3,3,3-trifluoropropyl group is preferred.

[0050] Examples of the alkoxy group that can constitute the substituent R include methoxy, ethoxy, propoxy, and isopropoxy groups.

[0051] From the viewpoint of ease of production of component (A) having a small polydispersity, the substituent R, excluding the hydrophilic group protected by an acid-decomposable functional group, is preferably a group having a large steric volume. Specifically, an alkyl group or aryl group having 3 or more carbon atoms (preferably 3 to 20 carbon atoms) is preferred. Taking economical advantages into consideration, a phenyl group is preferably used as the substituent R.

[0052] As described above, component (A) of the present invention has a hydrophilic group protected by an acid-decomposable functional group in the molecule, and specifically, it is necessary that at least one of the substituents R in the average unit formula (1) is a hydrophilic group protected by an acid-decomposable functional group.

[0053] In one embodiment of the present invention, the hydrophilic group protected with an acid-decomposable functional group may be a group represented by the following formula (2): *-R １ -O-R ２ (2) In formula (2), R １ is a divalent hydrocarbon group which may have a carbonyl group (-C(=O)-). ２ is a monovalent hydrocarbon group or trialkylsilyl group having 1 to 4 carbon atoms, and * is the bonding site to a silicon atom on the organopolysiloxane.

[0054] The linking group R in formula (2) １ The number of carbon atoms in the divalent hydrocarbon group which may have a carbonyl group (including the carbon atom of the carbonyl group when the divalent hydrocarbon group has a carbonyl group) constituting the above is not particularly limited, but can be, for example, from 2 to 7, or from 3 to 6. Furthermore, when the divalent hydrocarbon group has a carbonyl group, the carbonyl group may be located at either end of the divalent hydrocarbon group, or may be located between two adjacent carbon atoms which constitute the divalent hydrocarbon group.

[0055] R in formula (2) ２ As described above, R is a monovalent hydrocarbon group or trialkylsilyl group having 1 to 4 carbon atoms, and may be a monovalent saturated hydrocarbon group having 1 to 4 carbon atoms, or a monovalent branched saturated hydrocarbon group having 3 to 4 carbon atoms. ２ Specific examples of suitable groups include a tert-butyl group (a tertiary butyl group) and a trimethylsilyl group. ２ is more preferably a tert-butyl group.

[0056] In another embodiment of the present invention, the hydrophilic group protected with an acid-decomposable functional group is preferably a carboxylic acid ester-containing group represented by the following formula (2-A): ３ -CO ２ -R ４ (2-A) In formula (2-A), R ３ is a divalent hydrocarbon group having 2 to 6 carbon atoms. ４is a monovalent saturated hydrocarbon group or trialkylsilyl group having 1 to 4 carbon atoms. * is the bonding site to the silicon atom on the organopolysiloxane. ２ "-" means the structure "-C(=O)-O-".

[0057] The linking group R in formula (2-A) ３ The divalent hydrocarbon group having 2 to 6 carbon atoms constituting R may be linear or branched. ３ Specific examples of the alkyl group include an ethylene group, a propylene group, a 2-methylethylene group, a butylene group, a pentylene group, and a hexylene group, with a propylene group being preferred.

[0058] R, which is an ester moiety in formula (2-A), ４ is a monovalent hydrocarbon group or trialkylsilyl group having 1 to 4 carbon atoms, and may be a monovalent saturated hydrocarbon group having 1 to 4 carbon atoms, or a monovalent branched saturated hydrocarbon group having 3 to 4 carbon atoms. ４ Specific examples of suitable groups include a tert-butyl group (a tertiary butyl group) and a trimethylsilyl group. ４ As the alkyl group, a tert-butyl group is more preferred.

[0059] In yet another embodiment of the present invention, the hydrophilic group protected by an acid-decomposable functional group is preferably a phenol ether group represented by the following formula (2-B): By using component (A) having a phenol ether group represented by the following formula (2-B), the heat resistance of the resulting coating film can be improved.

[0060] In formula (2-B), R ５ is a monovalent branched saturated hydrocarbon group or trialkylsilyl group having 3 to 4 carbon atoms, and * is the bonding site to a silicon atom on the organopolysiloxane.

[0061] R in formula (2-B) ５As described above, R is a monovalent branched saturated hydrocarbon group or trialkylsilyl group having 3 to 4 carbon atoms, and specific examples of suitable groups include a tert-butyl group (tertiary butyl group) and a trimethylsilyl group. ５ is more preferably a tert-butyl group.

[0062] There is no limitation on the number of hydrophilic groups protected by acid-decomposable functional groups in the molecule of component (A). From the viewpoint of maintaining good alkali solubility of the branched polyorganosiloxane after high-energy ray irradiation, the number of siloxane units having a hydrophilic group protected by an acid-decomposable functional group in component (A) is preferably more than 20 mol% relative to the total number of siloxane units (100 mol%), more preferably more than 20 mol% but less than 80 mol%, and even more preferably more than 20 mol% but less than 60 mol%. In one embodiment of the present invention, the number of siloxane units having a hydrophilic group protected by an acid-decomposable functional group in component (A) may be 21 mol% or more and 39 mol% or less, or 22 mol% or more and 37 mol% or less, relative to the total number of siloxane units (100 mol%).

[0063] Here, component (A) may be used singly or in a combination of two or more types in any ratio. That is, component (A) in the present invention may be a branched organopolysiloxane having a single number of hydrophilic groups protected by acid-decomposable functional groups, or may be a mixture of two or more branched organopolysiloxanes each having a different number of hydrophilic groups protected by acid-decomposable functional groups.

[0064] The average number of hydrophilic groups protected by acid-decomposable functional groups contained in one molecule of component (A) of the present invention (hereinafter sometimes referred to as the "average number of protected hydrophilic groups per molecule") is preferably from 2 to 6, more preferably from 3 to 6. When the average number of protected hydrophilic groups per molecule is within the above-mentioned range, surface tack after coating and solvent removal is controlled, and component (A) can exhibit even better alkali solubility after high-energy radiation irradiation.

[0065] There are no particular restrictions on the site of the hydrophilic group protected by an acid-decomposable functional group in component (A) of the present invention, and it can be applied to any R in average unit formula (1) (i.e., any R in average unit formula (1) can be a "hydrophilic group protected by an acid-decomposable functional group"). However, considering that formula (1) satisfies the above formula: 0.8≦c and that the average number of protected hydrophilic groups per molecule is preferably 2 or more, it is preferable that the monoorganosiloxy unit (RSiO ３／２ ) ｃ It is preferred that all or part of R in the formula (I) is a hydrophilic group protected with an acid-decomposable functional group.

[0066] There are no particular limitations on the method for producing component (A) of the present invention. For example, the following production method 1) or 2) can be used to produce component (A): 1) Using a single or multiple alkoxysilanes, a reactive (e.g., silicon-bonded hydrogen-functional) branched organopolysiloxane having a predetermined molecular weight and a small polydispersity is produced by a controlled hydrolysis / condensation reaction, and then a compound containing a hydrophilic group protected by an acid-decomposable functional group is introduced into the resulting branched organopolysiloxane by a chemical reaction (e.g., hydrosilylation reaction); 2) A branched organopolysiloxane having a predetermined molecular weight and a small polydispersity is produced by a controlled hydrolysis / condensation reaction between a previously produced alkoxysilane containing a hydrophilic group protected by an acid-decomposable functional group and other optional alkoxysilanes.

[0067] In the present invention, production method 2) is preferably applicable. In this production method, the purity of the intermediate alkoxysilane containing a hydrophilic group protected by an acid-decomposable functional group can be increased by purifying it. This procedure also minimizes the risk of heavy metals such as platinum atoms being contained in the final product, the branched organopolysiloxane. This characteristic is important and offers a significant advantage when applied to electronic materials, particularly in the semiconductor field.

[0068] The above-mentioned method 2) will be further explained with a specific example. A trialkoxysilane having a hydrophilic group protected by an acid-decomposable functional group can be produced by carrying out a hydrosilylation reaction between a compound containing both a reactive carbon-carbon double bond-containing organic group (e.g., a vinyl group) and a hydrophilic group protected by an acid-decomposable functional group and a trialkoxysilane. The product can then be purified by a method such as vacuum distillation to obtain a functional trialkoxysilane free of heavy metal impurities.

[0069] The mixture of the trialkoxysilane (preferably trimethoxysilane) having a hydrophilic group protected by an acid-decomposable functional group obtained above and an optional other trialkoxysilane (preferably trimethoxysilane) is subjected to a controlled hydrolysis / condensation reaction in the presence of a basic catalyst to produce a reactive branched organopolysiloxane with a low polydispersity. The molecular weight of the product can be controlled by the type and amount of solvent used during the reaction and the amount of water used. It is particularly preferred that the reactive branched organopolysiloxane at this stage has the aforementioned cage molecular structure.

[0070] <Component (B): Photoacid Generator> Component (B) is a component that catalyzes the decomposition reaction of component (A) by high-energy rays, and typically, compounds known as photoacid generators for cationic polymerization can be used. Known photoacid generators include compounds that can generate a Brønsted acid or Lewis acid upon irradiation with high-energy rays.

[0071] The photoacid generator used in the branched organopolysiloxane composition of the present invention can be selected from those known in the art and is not particularly limited. Known photoacid generators include strong acid-generating compounds such as diazonium salts, sulfonium salts, iodonium salts, and phosphonium salts, and these can be used. The photoacid generators may be used alone or in combination of two or more in any ratio.

[0072] Specific examples of photoacid generators include bis(4-tert-butylphenyl)iodonium hexafluorophosphate, cyclopropyldiphenylsulfonium tetrafluoroborate, dimethylphenacylsulfonium tetrafluoroborate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroarsenate, diphenyliodonium tetrafluoromethanesulfonate, 2-(3,4-dimethoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-[2-(furan-2-yl)vinyl]-4,6-bis(trichloromethyl)-1,3,5-triazine, and 4-isopropyl-4'-methyldiphenyliodonium. Tetrakis(pentafluorophenyl)borate, 2-[2-(5-methylfuran-2-yl)vinyl]-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(4-methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 4-nitrobenzenediazonium tetrafluoroborate, triphenylsulfonium tetrafluoroborate, triphenylsulfonium bromide, tri-p-tolylsulfonium hexafluorophosphate, tri-p-tolylsulfonium trifluoromethanesulfonate, triarylsulfonium tetrakis(pentafluorophenyl)borate, diphenyliodonium triflate, triphenylsulfonium triflate, diphenyliodonium nitrate, bis(4-tert-butylphenyl)iodonium Perfluoro-1-butanesulfonate, bis(4-tert-butylphenyl)iodonium triflate, triphenylsulfonium perfluoro-1-butanesulfonate, N-hydroxynaphthalimide triflate, p-toluenesulfonate, diphenyliodonium p-toluenesulfonate, (4-tert-butylphenyl)diphenylsulfonium triflate, tris(4-tert-butylphenyl)sulfonium triflate, N-hydroxy-5-norbornene-2,Examples of photoacid generators include, but are not limited to, 3-dicarboximide perfluoro-1-butanesulfonate, (4-phenylthiophenyl)diphenylsulfonium triflate, and 4-(phenylthio)phenyldiphenylsulfonium triethyltrifluorophosphate. Commercially available photoacid generators include Omnicat® 250 and Omnicat 270 (both from IGM Resins BV), CPI-310B and IK-1 (both from San-Apro Co., Ltd.), DTS-200 (Midori Chemical Co., Ltd.), TS-01 and TS-91 (both from Sanwa Chemical Co., Ltd.), and Irgacure® 290 (BASF).

[0073] The amount of photoacid generator added to the branched organopolysiloxane composition of the present invention is not particularly limited as long as the desired photodecomposition reaction occurs. The content of component (B) in the branched organopolysiloxane composition is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, even more preferably 0.5 to 10 parts by mass, and particularly preferably 1 to 10 parts by mass, per 100 parts by mass of the branched organopolysiloxane of component (A) of the present invention.

[0074] <Component (C): Organic Solvent> The branched organopolysiloxane composition of the present invention contains an organic solvent as component (C) for the purposes of improving the coatability of the branched organopolysiloxane, adjusting the thickness of the coating film, and improving the dispersibility of the photoacid generator. As such an organic solvent, any organic solvent that has conventionally been incorporated into various insulating coating materials and resist materials can be used without particular limitation. One organic solvent may be used alone, or two or more organic solvents may be used in any combination in any ratio, taking into account the miscibility with the above-mentioned components (A) and (B).

[0075] Specific examples of the organic solvent include (poly)alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, and dipropylene glycol mono-n-butyl ether; (Poly)alkylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA), and propylene glycol monoethyl ether acetate; other ethers such as diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, and diethylene glycol diethyl ether; ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 2-heptanone, 3-heptanone, 4-heptanone, 5-methyl-3-heptanone, 2,4-dimethyl-3-pentanone, and 2,6-dimethyl-4-heptanone; alkyl lactate esters such as methyl 2-hydroxypropionate and ethyl 2-hydroxypropionate;Other esters such as ethyl 2-hydroxy-2-methylpropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanoate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutylpropionate, ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, n-pentyl formate, i-pentyl acetate, n-butyl propionate, ethyl butyrate, n-propyl butyrate, i-propyl butyrate, n-butyl butyrate, methyl pyruvate, ethyl pyruvate, n-propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, and ethyl 2-oxobutanoate; Aromatic hydrocarbons such as toluene, xylene, mesitylene, cumene, propylbenzene, diethylbenzene, and 1,3-diisopropylbenzene; and aromatic ethers such as anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 3,4-dimethoxytoluene, and 1,4-bis(methoxymethyl)benzene.

[0076] The content of the organic solvent in the branched organopolysiloxane composition of the present invention is not particularly limited and can be appropriately set depending on factors such as miscibility with the branched organopolysiloxane (A) and the thickness of the coating film formed from the composition. The content of component (B) in the branched organopolysiloxane composition can be, for example, 10 parts by mass or more and 5,000 parts by mass or less per 100 parts by mass of the branched organopolysiloxane (component (A)) of the present invention. In the branched organopolysiloxane composition of the present invention, the solute concentration of the branched organopolysiloxane (component (A)) is preferably 2% by mass or more and 90% by mass or less, more preferably 2% by mass or more and 50% by mass or less.

[0077] The coating film obtained from the branched organopolysiloxane composition of the present invention can have desired physical properties depending on the molecular structure of component (A), the chemical structure of the hydrophilic group protected by an acid-decomposable functional group, the chemical structure of other substituents, and the number of hydrophilic groups protected by an acid-decomposable functional group per molecule. Furthermore, in the present invention, the viscosity of the composition can be designed to a desired value depending on the amount of component (C). Similarly, the viscosity of the coating film obtained by irradiating the branched organopolysiloxane composition of the present invention with high-energy radiation can be designed to a desired value depending on the structure and amount of the above components, as well as the molecular structure and amount of component (B), and desired physical properties can be obtained. The shape of the coating film obtained from the composition of the present invention is not particularly limited; it can be a thin-film coating layer or a sheet-like molded product, and can be used as a sealant or intermediate layer for laminates, display devices, etc. The coating film obtained from the composition of the present invention is preferably in the form of a thin-film coating layer, and particularly preferably a thin-film insulating coating layer or resist layer.

[0078] The branched organopolysiloxane composition of the present invention is suitable for use as a coating agent, particularly as an insulating coating agent for electronic and electrical devices, and is also suitable for use as a resist material using short-wavelength light such as an excimer laser as a light source.

[0079] <Other Additives> In addition to the above components, further additives may be added to the composition of the present invention as desired. Examples of additives include, but are not limited to, those listed below. Note that the other additives may be used alone or in combination of two or more in any ratio.

[0080] -Adhesion Imparting Agent- An adhesion imparting agent can be added to the branched organopolysiloxane composition of the present invention in order to improve the adhesion or adhesion to a substrate that comes into contact with the composition. When the composition of the present invention is used in applications that require adhesion or adhesion to a substrate, such as a coating agent or sealant, it is preferable to add an adhesion imparting agent to the composition of the present invention. Any known adhesion imparting agent can be used as this adhesion imparting agent, as long as it does not inhibit the decomposition reaction of the composition of the present invention in the presence of acid.

[0081] Examples of adhesion promoters that can be used in the present invention include organosilanes having a trialkoxysiloxy group (e.g., trimethoxysiloxy group, triethoxysiloxy group) and / or a trialkoxysilylalkyl group (e.g., trimethoxysilylethyl group, triethoxysilylethyl group), and a hydrosilyl group and / or an alkenyl group (e.g., vinyl group, allyl group); organosiloxane oligomers having a linear, branched, or cyclic structure and about 4 to 20 silicon atoms, and having a trialkoxysiloxy group and / or a trialkoxysilylalkyl group, and a hydrosilyl group and / or an alkenyl group; organosilanes having a trialkoxysiloxy group and / or a trialkoxysilylalkyl group, and a methacryloxyalkyl group (e.g., 3-methacryloxypropyl group); Organosiloxane oligomers having a linear, branched, or cyclic structure and having about 4 to 20 silicon atoms, which have a trialkoxysiloxy group and / or a trialkoxysilylalkyl group and a methacryloxyalkyl group; organosilanes having a trialkoxysiloxy group and / or a trialkoxysilylalkyl group and an epoxy group-bonded alkyl group (e.g., 3-glycidoxypropyl group, 4-glycidoxybutyl group, 2-(3,4-epoxycyclohexyl)ethyl group, 3-(3,4-epoxycyclohexyl)propyl group); organosiloxane oligomers having a linear, branched, or cyclic structure and having about 4 to 20 silicon atoms, which have a trialkoxysiloxy group and / or a trialkoxysilylalkyl group and an epoxy group-bonded alkyl group; organic compounds having two or more trialkoxysilyl groups (e.g., trimethoxysilyl group, triethoxysilyl group); reaction products of aminoalkyltrialkoxysilanes and epoxy group-bonded alkyltrialkoxysilanes; epoxy group-containing ethyl polysilicate;

[0082] More specifically, the adhesion promoter is not particularly limited, but examples thereof include vinyltrimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, hydrogentriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 1,6-bis(trimethoxysilyl)hexane, 1,6-bis(triethoxy ...

[0033] Examples of suitable silanol-blocking agents include tris(3-trimethoxysilyl)hexane, 1,3-bis[2-(trimethoxysilyl)ethyl]-1,1,3,3-tetramethyldisiloxane, a reaction product of 3-glycidoxypropyltriethoxysilane and 3-aminopropyltriethoxysilane, a condensation reaction product of a silanol-blocking methylvinylsiloxane oligomer and 3-glycidoxypropyltrimethoxysilane, a condensation reaction product of a silanol-blocking methylvinylsiloxane oligomer and 3-methacryloxypropyltriethoxysilane, and tris(3-trimethoxysilylpropyl)isocyanurate.

[0083] There are no particular restrictions on the amount of adhesion promoter added to the composition of the present invention, but from the viewpoint of not promoting decomposition reactions of the composition or discoloration of the branched organopolysiloxane, it is preferably in the range of 0.01 to 5 parts by mass, or in the range of 0.01 to 2 parts by mass, per 100 parts by mass of component (A).

[0084] - Further Optional Additives - In addition to or instead of the adhesion promoter described above, other additives may be added to the composition of the present invention as desired. Examples of additives that can be used include leveling agents, silane coupling agents not included in the adhesion promoters described above, high-energy ray absorbers, antioxidants, polymerization inhibitors, and fillers (functional fillers such as reinforcing fillers, insulating fillers, and thermally conductive fillers). Appropriate additives can be added to the composition of the present invention as needed. Furthermore, a thixotropic agent may be added to the composition of the present invention as needed, particularly when used as a sealing material.

[0085] <Method for producing a coating film> There are no particular limitations on the method for producing a coating film using the branched polyorganosiloxane composition of the present invention. Known lithography processes can be applied to produce a coating film, and patterned coating films can also be produced, which is preferable. A typical method for producing a patterned coating film is recommended, which includes: 1) forming a coating film of the above-mentioned branched organopolysiloxane composition on a substrate; 2) heating the obtained coating film for a short time at a temperature of about 120°C or less to remove the solvent (organic solvent); 3) regioselectively exposing the coating film; and 4) developing the exposed coating film to obtain a patterned coating film. If necessary, a short heating step can be inserted between 3) and 4).

[0086] The manufacturing method is described in detail below. The substrate is not particularly limited, and various substrates can be used, such as a glass substrate, a silicon substrate, and a glass substrate coated with a transparent conductive film.

[0087] The branched organopolysiloxane composition of the present invention can be applied to a substrate by known methods using a coating device such as a spin coater, roll coater, bar coater, or slit coater. The applied composition is usually heated and dried to remove the solvent. Typical methods include drying on a hot plate or in an oven at a temperature of 80°C to 120°C, preferably 90°C to 100°C, for 1 to 2 minutes, leaving the composition at room temperature for several hours, or heating in a hot air heater or infrared heater for several tens of minutes to several hours.

[0088] The position-selective exposure of the coating film is usually carried out through a photomask or the like using a high-energy ray light source such as a high-pressure mercury lamp, a metal halide lamp, or an LED lamp, a laser light source such as an excimer laser, or a known actinic energy ray light source including UEV. Depending on the properties of the composition, a negative or positive photomask can be used. The energy dose to be irradiated depends on the structure of the curable composition, but is typically 3 to 1,000 mJ / cm. ２Furthermore, if necessary, the composition coating film after exposure may be subjected to a heat treatment (post-exposure bake) to increase the decomposition reaction yield. The conditions for this are usually a temperature of 100°C or higher and 150°C or lower for 1 to 2 minutes.

[0089] Development with a developer is carried out to form a pattern of the desired shape. Known developers include aqueous alkaline solutions and organic solvents, but when using the branched organopolysiloxane composition of the present invention, development with an aqueous alkaline solution is preferred. Both aqueous solutions of inorganic bases and aqueous solutions of organic bases can be used as the aqueous alkaline solution. Examples of aqueous alkaline solutions suitable as developers include aqueous solutions of basic substances such as sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia, and quaternary ammonium salts, with an aqueous solution of tetramethylammonium hydroxide (TMAH) being particularly preferred. The development method is not particularly limited, and examples of applicable methods include dipping and spraying.

[0090] As described above, the branched organopolysiloxane of the present invention and compositions containing it as a main component have good coatability, and also have remarkably excellent alkali solubility after irradiation with high-energy rays. Therefore, particularly when subjected to a development step using an aqueous alkaline solution, they have the advantages of being able to easily form patterns with high precision and of producing coating films with excellent mechanical strength and transparency.

[0091] By the above operations, a coating film of the branched organopolysiloxane can be formed that is patterned into the desired shape.

[0092] <Applications> The branched organopolysiloxane composition of the present invention is particularly useful as a material for forming insulating layers and resist materials for various articles, particularly electronic and electrical devices. Furthermore, because the coating films obtained from the composition of the present invention have good transparency, the composition is also suitable as a material for forming insulating layers in display devices such as touch panels and displays. In this case, the insulating layer may be formed into any desired pattern, as described above, if necessary. Therefore, display devices such as touch panels and displays that include an insulating layer obtained by irradiating the branched organopolysiloxane composition of the present invention with or without high-energy radiation also constitute one embodiment of the present invention.

[0093] Furthermore, an insulating coating layer (insulating film) can be formed by coating an article with the composition of the present invention and then removing the organic solvent. Therefore, the composition of the present invention can be used as an insulating coating agent. Furthermore, a coating film formed by removing the organic solvent from the composition of the present invention can also be used as an insulating coating layer.

[0094] The insulating film formed from the composition of the present invention can be used in various applications other than the display device. In particular, it can be used as a component of an electronic device or as a material used in the process of manufacturing an electronic device. Electronic devices include electronic devices such as semiconductor devices and magnetic recording heads. For example, the composition of the present invention can be used as an insulating film for semiconductor devices, such as LSIs, system LSIs, DRAMs, SDRAMs, RDRAMs, D-RDRAMs, and multi-chip module multilayer wiring boards, an interlayer insulating film for semiconductors, an etching stopper film, a surface protective film, a buffer coating film, a passivation film in LSIs, a cover coat for flexible copper-clad boards, a solder resist film, and a surface protective film for optical devices.

[0095] The present invention will be further described below based on examples, but the present invention is not limited to the following examples.

[0096] The synthesis of the branched organopolysiloxane of the present invention and the preparation and evaluation of the branched organopolysiloxane composition are described in detail in the following examples. Note that the number average molecular weight (Mn), weight average molecular weight (Mw), and polydispersity index (PDI), defined as the value of "Mw / Mn," used in the examples are as described above.

[0097] <Appearance of Branched Organopolysiloxane Composition> Branched organopolysiloxane compositions prepared by adding a photoacid generator (B1) to the branched organopolysiloxane (solution state) shown below at the mass ratios shown in Tables 1 and 2 below were visually observed, and the appearance, including transparency, was evaluated. A1: Branched organopolysiloxane obtained in Example 1 A2: Branched organopolysiloxane obtained in Example 2 A3: Branched organopolysiloxane obtained in Example 3 A4: Branched organopolysiloxane obtained in Synthesis Example 2 A5: Branched organopolysiloxane obtained in Synthesis Example 3 A6: Branched organopolysiloxane obtained in Example 7 A7: Branched organopolysiloxane obtained in Example 8 A8: Branched organopolysiloxane obtained in Synthesis Example 4 B1: Sulfonium-based photoacid generator: triarylsulfonium tetrakis(pentafluorophenyl)borate (trade name: Irgacure 290), manufactured by BASF

[0098] <Transparency of Branched Organopolysiloxane> The above-described branched organopolysiloxane composition was spin-coated onto an optical glass substrate to a film thickness of approximately 0.5 μm, and the resulting coating was pre-baked at 100° C. for 1 minute using a hot plate to form a coating film (Coating Film X). The total light transmittance of the resulting coating film at 25° C. was measured using a haze meter SH7000 manufactured by Nippon Denshoku Industries Co., Ltd. The coating film thus formed was also irradiated with a high-pressure mercury lamp to a light intensity of 40 mJ / cm at a wavelength of 254 nm. ２ After that, PEB was carried out for 2 minutes at 120° C. The total light transmittance at 25° C. of the coating film obtained by this operation (coating film Y) was measured in the same manner.

[0099] <Alkali Solubility of Branched Organopolysiloxane> Coatings X and Y, each having a thickness of approximately 0.2 μm and formed by the same method as above, were developed at 25° C. for 1 minute using a 2.38 mass % aqueous solution of tetramethylammonium hydroxide (TMAH), and then immersed and washed in a water bath at room temperature (25° C.). The washing time was 15 seconds. After washing, the glass substrate was dried to remove moisture, and then visually observed, and the solubility in the alkaline aqueous solution (developability) was evaluated according to the following criteria: A: Completely dissolved: The coating film was completely removed. B: Almost dissolved: A small amount (less than 5% of the planar area) of remaining coating film (scum) was observed. C: Insoluble

[0100] Synthesis Example 1: Synthesis of tert-butoxycarbonylpropyltrimethoxysilane (M1) 74.6 g of tert-butyl-3-butenate and a toluene solution of Karstedt's catalyst in an amount equivalent to 100 ppm of platinum were added to a 300 mL three-neck flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube, and the mixture was stirred thoroughly. A mixture of 65.5 g of trimethoxysilane and 1.0 g of acetic acid was slowly added dropwise to the solution under a nitrogen atmosphere, followed by stirring at room temperature for 90 minutes. The product was distilled under reduced pressure to obtain 116 g of the target silane (M1) (83% isolated yield). The product had the following structure: １３ Confirmed by C NMR spectroscopy.

[0101] Example 1: Synthesis of tert-butoxycarbonylpropyl- and phenyl-functional branched organopolysiloxane (A1) 20.0 g of the silane (M1) obtained in Synthesis Example 1, 45.0 g of phenyltrimethoxysilane, and 310 g of tetrahydrofuran were added to a 500 mL three-neck flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube, and the mixture was stirred thoroughly. A mixed solution of 1.0 g of potassium hydroxide and 8.4 g of water was added to the resulting solution, and the mixture was stirred at 60°C for 6 hours. The resulting reaction solution was cooled to room temperature, and 7.0 g of an alkali adsorbent, Kyoward® 700PL, was added, followed by stirring at room temperature for 30 minutes. After stirring, a white solid was filtered from the reaction solution, and most of the volatiles were removed, yielding a concentrated solution of functional branched organopolysiloxane (solid content of 70% by mass or more). 100 mL of PGMEA was added to this solution, and the low boiling point components were removed. This process was then repeated to obtain a 20% by mass PGMEA solution of the product. １３ C, and ２９ Evaluation by Si NMR spectroscopy confirmed that this was a branched organopolysiloxane (A1) in which 25 mol % of the substituents on the silicon atoms were tert-butoxycarbonylpropyl group-containing T units and 75 mol % were phenyl group-containing T units. It was also confirmed that the amount of residual groups (value of e) was less than 0.01. That is, the average unit formula of the branched organopolysiloxane (A1) can be expressed as follows: (RSiO ３／２ ) 0.25 ((C ６ H ５ ) SiO ３／２ ) 0.75 (O １／２ Z) <0.01 In the above formula, R represents a tert-butoxycarbonylpropyl group (-C ３ H ６ -C(=O)-OC(CH ３ ) ３ The Mn, Mw, and PDI of the branched organopolysiloxane (A1), calculated in terms of standard polystyrene by GPC, were 1,000, 1,100, and 1.10, respectively. The average number of silicon atoms per molecule (calculated from the above Mn) was 7.

[0102] Example 2: Synthesis of tert-butoxycarbonylpropyl- and cyclohexyl-functional branched organopolysiloxane (A2) The reaction was carried out in the same manner as in Example 1, except that the amount of silane (M1) was changed to 21.6 g, 50.0 g of cyclohexyltrimethoxysilane was used instead of 45.0 g of phenyltrimethoxysilane, 300 g of tetrahydrofuran, 2.2 g of potassium hydroxide, 9.1 g of water, and 14.0 g of Kyoward 700PL were used. A 20% by weight PGMEA solution of the product was obtained. Characterization was carried out in the same manner as in Example 1, and the product was confirmed to be a branched organopolysiloxane (A2) in which 25 mol % of the substituents on the silicon atoms were tert-butoxycarbonylpropyl-containing T units and 75 mol % were cyclohexyl-containing T units. The residual group content (e value) was also confirmed to be 0.09. That is, the average unit formula of the branched organopolysiloxane (A2) can be expressed as follows: (RSiO ３／２ ) 0.25 ((C ６ H １１ ) SiO ３／２ ) 0.75 (O １／２ Z) 0.09 In the above formula, R represents a tert-butoxycarbonylpropyl group (-C ３ H ６ -C(=O)-OC(CH ３ ) ３ The Mn, Mw, and PDI of the branched organopolysiloxane (A2), calculated in terms of standard polystyrene by GPC, were 1,200, 1,400, and 1.17, respectively. The average number of silicon atoms per molecule (calculated from the above Mn) was 8.

[0103] Example 3: Synthesis of tert-butoxycarbonylpropyl- and methyl-functional branched organopolysiloxane (A3) The reaction was carried out in the same manner as in Example 1, except that the amount of silane (M1) was changed to 15.0 g, 23.2 g of methyltrimethoxysilane was used instead of 45.0 g of phenyltrimethoxysilane, 180 g of tetrahydrofuran, 0.75 g of potassium hydroxide, 6.3 g of water, and 5.0 g of Kyoward 700PL were used. A 25% by mass PGMEA solution of the product was obtained. Characterization was carried out in the same manner as in Example 1, and the product was confirmed to be a branched organopolysiloxane (A3) in which 20 mol % of the substituents on the silicon atoms were tert-butoxycarbonylpropyl-containing T units and 75 mol % were methyl-containing T units. The residual group content (e value) was confirmed to be 0.02. That is, the average unit formula of the branched organopolysiloxane (A3) can be expressed as follows: (RSiO ３／２ ) ０．２５ ((CH ３ ) SiO ３／２ ) ０．７５ (O １／２ Z) 0.02 In the above formula, R represents a tert-butoxycarbonylpropyl group (-C ３ H ６ -C(=O)-OC(CH ３ ) ３ The Mn, Mw, and PDI of the branched organopolysiloxane (A3), calculated in terms of standard polystyrene by GPC, were 800, 1,040, and 1.30, respectively. The average number of silicon atoms per molecule (calculated from the above Mn) was 8.

[0104] Synthesis Example 2: Synthesis of methacryloxypropyl- and phenyl-functional branched organopolysiloxane (A4) The reaction was carried out in the same manner as in Example 1, except that 65.0 g of methacryloxypropyltrimethoxysilane was used instead of 20.0 g of silane (M1), and the amounts of phenyltrimethoxysilane, tetrahydrofuran, potassium hydroxide, water, and Kyoward 700PL were changed to 31.1 g, 200 g, 0.9 g, 11.6 g, and 8.0 g, respectively, to obtain a 20% by weight PGMEA solution of the product. Characterization was carried out in the same manner as in Example 1, and the product was confirmed to be a branched organopolysiloxane (A4) in which 62.5 mol% of the substituents on the silicon atoms were methacryloxypropyl-containing T units and 37.5 mol% were phenyl-containing T units. The residual group content (e value) was also confirmed to be less than 0.01. That is, the average unit formula of the branched organopolysiloxane (A4) can be expressed as follows: (RSiO ３／２ ) 0.625 ((C ６ H ５ ) SiO ３／２ ) 0.375 (O １／２ Z) <0.01 In the above formula, R represents a methacryloxypropyl group (-C ３ H ６ -OC(=O)-C(CH ３ ) = CH ２ The Mn, Mw, and PDI of the branched organopolysiloxane (A4), calculated in terms of standard polystyrene by GPC, were 1,230, 1,430, and 1.16, respectively. The average number of silicon atoms per molecule (calculated from the above Mn) was 8.

[0105] Synthesis Example 3: Synthesis of tert-butoxycarbonylpropyl- and phenyl-functional branched organopolysiloxane (A5) A toluene solution of an epoxy-functional branched polysiloxane (solid content: 78% by mass, hereinafter referred to as "P1 solution") was produced by the method described in Synthesis Example 3 of WO 2023-074804. Characterization was carried out in the same manner as in Example 1, and the product was confirmed to be a branched organopolysiloxane (P1) having the following structure (average unit formula). Structure of P1: The Mn, Mw, and PDI of the branched organopolysiloxane (P1) calculated using standard polystyrene standards by GPC were 5,000, 12,000, and 2.40, respectively. The average number of silicon atoms per molecule (calculated from the Mn) was 36. Next, 36.9 g of the P1 solution obtained above, 9.4 g of mono-tert-butyl succinate, and 0.24 g of tetramethylammonium bromide were added to a 200 mL three-neck flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube, and the mixture was stirred at 100°C for 42 hours. The reaction solution was then allowed to cool to room temperature and filtered. PGMEA was then added, and solvent substitution was repeated to obtain a product: a PGMEA solution with a solids concentration of 50% by mass. Characterization was carried out in the same manner as in Example 1, and the product was confirmed to be a branched organopolysiloxane (A5) containing a hydrophilic group protected by an acid-decomposable functional group, having the following structure: Structure of A5: The Mn, Mw, and PDI of the branched organopolysiloxane (A5), calculated based on standard polystyrene standards by GPC, were 7,000, 16,700, and 2.39, respectively, and the average number of silicon atoms per molecule (calculated from the above Mn) was 38.

[0106] Example 7: Synthesis of tert-butoxyphenyl- and methyl-functional branched organopolysiloxane (A6) 6.0 g of methyltrimethoxysilane, 11.9 g of 1-tert-butoxy-4-trimethoxysilylbenzene, and 90 g of tetrahydrofuran were placed in a 300 mL three-neck flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube, and stirred thoroughly. A mixed solution of 0.3 g of 34 wt% aqueous potassium hydroxide solution and 2.4 g of water was added to the resulting solution, and the mixture was stirred at 60°C for 6 hours. The resulting reaction solution was cooled to room temperature, and 1.9 g of Kyoward 700PL alkali adsorbent was added and stirred at room temperature for 30 minutes. After stirring, a white solid was filtered from the reaction solution, and most of the volatiles were removed, yielding a concentrated solution of functional branched organopolysiloxane (solids content of 70 wt% or more). 100 mL of PGMEA was added to this solution, and the low-boiling components were removed. This process was repeated to obtain a 20 mass % PGMEA solution of the product. Characterization was carried out in the same manner as in Example 1, and the product was confirmed to be a branched organopolysiloxane (A6) in which 50 mol % of the substituents on the silicon atoms were methyl group-containing T units and 50 mol % were tert-butoxyphenyl group-containing T units. The amount of residual groups (value of e) was also confirmed to be 0.01. That is, the average unit formula of branched organopolysiloxane (A6) can be expressed as follows: ((CH ３ ) SiO ３／２ ) 0.50 (RSiO ３／２ ) 0.50 (O １／２ Z) 0.01 In the above formula, R represents a tert-butoxyphenyl group (-C ６ H ５ —O—C(CH ３ ) ３ The Mn, Mw, and PDI of the branched organopolysiloxane (A6), calculated in terms of standard polystyrene by GPC, were 1,020, 1,200, and 1.18, respectively. The average number of silicon atoms per molecule (calculated from the above Mn) was 8.

[0107] Example 8: Synthesis of tert-butoxyphenyl- and propyl-functional branched organopolysiloxane (A7) The reaction was carried out in the same manner as in Example 7, except that 2.6 g of propyltrimethoxysilane was used instead of 6.0 g of methyltrimethoxysilane, and the amounts of 1-tert-butoxy-4-trimethoxysilylbenzene, 12.8 g of tetrahydrofuran, 0.2 g of 34 wt% aqueous potassium hydroxide solution, and 1.7 g of water were changed. A 20 wt% PGMEA solution of the product was obtained. Characterization was carried out in the same manner as in Example 1, and the product was confirmed to be a branched organopolysiloxane (A7) in which 25 mol% of the substituents on the silicon atoms were propyl-containing T units and 75 mol% were tert-butoxyphenyl-containing T units. The residual group content (e value) was also confirmed to be less than 0.01. The average unit formula of branched organopolysiloxane (A7) can be expressed as follows: ((C ３ H ７ ) SiO ３／２ ) 0.25 (RSiO ３／２ ) 0.75 (O １／２ Z) <0.01 In the above formula, R represents a tert-butoxyphenyl group (-C ６ H ５ —O—C(CH ３ ) ３ The Mn, Mw, and PDI of the branched organopolysiloxane (A7), calculated in terms of standard polystyrene by GPC, were 1,330, 1,370, and 1.03, respectively. The average number of silicon atoms per molecule (calculated from the above Mn) was 8.

[0108] Synthesis Example 4 Synthesis of methoxyphenyl- and methyl-functional branched organopolysiloxane (A8) The reaction was carried out in the same manner as in Example 7, except that 10.1 g of 1-methoxy-4-trimethoxysilylbenzene was used instead of 11.9 g of 1-tert-butoxy-4-trimethoxysilylbenzene, to obtain a 20 mass % PGMEA solution of the product. Characterization was carried out in the same manner as in Example 1, and the product was confirmed to be branched organopolysiloxane (A8) in which 50 mol % of the substituents on the silicon atoms were methyl-group-containing T units and 50 mol % were methoxyphenyl-group-containing T units. The amount of residual groups (value of e) was also confirmed to be less than 0.01. That is, the average unit formula of branched organopolysiloxane (A8) can be expressed as follows: ((CH ３ ) SiO ３／２ ) 0.50 (RSiO ３／２ ) 0.50 (O １／２ Z) <0.01 In the above formula, R represents a methoxyphenyl group (-C ６ H ５ -O-CH ３ The Mn, Mw, and PDI of the branched organopolysiloxane (A8), calculated in terms of standard polystyrene by GPC, were 950, 1,120, and 1.18, respectively. The average number of silicon atoms per molecule (calculated from the above Mn) was 8.

[0109] Examples 4 to 6 and Comparative Examples 1 and 2: Evaluation of Branched Organopolysiloxanes The evaluation results of the branched organopolysiloxanes of the present invention are summarized in Table 1. The unit of the numerical values ​​for each component in Table 1 is "parts by mass" unless otherwise specified (in particular, the amount calculated as solid content, except for the organic solvent C1).

[0110]

[0111] As shown in Table 1, the coating films (Examples 4 to 6) formed from the branched organopolysiloxanes of the present invention (Examples 1 to 3: A1 to A3) exhibited high transparency, and the coating films after high-energy ray irradiation and PEB exhibited excellent alkali solubility. On the other hand, it was confirmed that the coating film (Comparative Example 1) formed from a branched organopolysiloxane that did not have a hydrophilic group protected by an acid-decomposable functional group exhibited high transparency, but did not exhibit alkali solubility, regardless of whether high-energy ray irradiation or PEB processing was performed. Furthermore, the coating film (Comparative Example 2) formed from a branched organopolysiloxane that had a hydrophilic group protected by an acid-decomposable functional group but had both a large molecular weight and a large PDI was insoluble in an alkaline aqueous solution even after high-energy ray irradiation and PEB.

[0112] Examples 9 to 10 and Comparative Example 3 Evaluation of Branched Organopolysiloxanes The evaluation results of the branched organopolysiloxanes of the present invention are summarized in Table 2. The unit of the numerical values ​​for each component in Table 2 is "parts by mass" unless otherwise specified (in particular, the amount is calculated as solid content, except for the organic solvent C1).

[0113] As shown in Table 2, the coating films (Examples 9 and 10) formed from the branched organopolysiloxanes of the present invention (Examples 7 and 8: A6 and A7) exhibited high transparency, and the coating films after high-energy ray irradiation and PEB exhibited excellent alkali solubility. On the other hand, it was confirmed that the coating film formed from the branched organopolysiloxane not having a hydrophilic group protected by an acid-decomposable functional group (Comparative Example 3) exhibited high transparency but did not exhibit alkali solubility, regardless of whether high-energy ray irradiation or PEB processing was performed.

[0114] The branched organopolysiloxane having a hydrophilic group protected by an acid-decomposable functional group and a composition containing the same as a main component according to the present invention exhibit excellent coatability on various substrates. The composition exhibits improved hydrophilicity and increased solubility in aqueous alkaline solutions after high-energy radiation exposure through deprotection of the hydrophilic group and subsequent post-exposure bake (PEB). Furthermore, the low molecular weight and polydispersity of the branched polysiloxane enable simple and highly accurate patterning in the lithography process used to form patterns of desired shapes. Additionally, coatings formed from the branched organopolysiloxane composition of the present invention have the advantages of being optically transparent and allowing for a wide range of hardness and other properties to be designed. Therefore, the composition according to the present invention is useful as a resist material for use with a wide range of light sources, particularly short-wavelength light sources. It is also useful as a material for insulating layers, particularly patterning materials and coating materials, for electronic devices, particularly thin-film displays such as OLEDs.

Claims

1. A branched organopolysiloxane represented by the following average unit formula (1), having a weight average molecular weight of 2,000 or less in terms of standard polystyrene and a polydispersity of 1.30 or less, as measured by gel permeation chromatography. (R ３ SiO １／２ ) ａ (R ２ SiO ２／２ ) ｂ (RSiO ３／２ ) ｃ (SiO ４／２ ) ｄ (O １／２ Z) ｅ (1) [In formula (1), R is each independently a group selected from the group consisting of unsubstituted or fluorine-substituted monovalent hydrocarbon groups, alkoxy groups, hydroxyl groups, and hydrophilic groups protected with an acid-decomposable functional group, Z is a hydrogen atom or an alkyl group, and a, b, c, d, and e are numbers that satisfy the following conditions: 0≦a, 0≦b, 0.8≦c, 0≦d, 0≦e, and a+b+c+d=1. The branched organopolysiloxane represented by the average unit formula (1) has at least one hydrophilic group protected with an acid-decomposable functional group in the molecule.] 2. The branched organopolysiloxane according to claim 1, wherein a is 0, b is 0, and d is 0.

3. The branched organopolysiloxane according to claim 1, wherein the number of siloxane units having a hydrophilic group protected with an acid-decomposable functional group is more than 20 mol % based on the number of all siloxane units.

4. The branched organopolysiloxane according to claim 1, wherein the hydrophilic group protected with an acid-decomposable functional group is a group represented by the following formula (2): *-R １ -O-R ２ (2) [In formula (2), R １ is a divalent hydrocarbon group which may have a carbonyl group, R ２ is a monovalent hydrocarbon group having 1 to 4 carbon atoms or a trialkylsilyl group, and * is a bonding site to a silicon atom on the organopolysiloxane.

5. The above R ２ 5. The branched organopolysiloxane of claim 4, wherein is a tert-butyl group.

6. The branched organopolysiloxane according to claim 1, wherein the hydrophilic group protected with an acid-decomposable functional group is a carboxylate-containing group represented by the following formula (2-A): ３ -CO ２ -R ４ (2-A) [In formula (2-A), R ３ is a divalent hydrocarbon group having 2 to 6 carbon atoms; R ４ is a monovalent hydrocarbon group having 1 to 4 carbon atoms or a trialkylsilyl group, and * is a bonding site to a silicon atom on the organopolysiloxane.

7. The above R ４ 7. The branched organopolysiloxane of claim 6, wherein is a tert-butyl group.

8. The branched organopolysiloxane according to claim 1, wherein the hydrophilic group protected with an acid-decomposable functional group is a phenol ether group represented by the following formula (2-B): [In formula (2-B), R ５ is a monovalent branched saturated hydrocarbon group having 3 to 4 carbon atoms or a trialkylsilyl group, and * is a bonding site to a silicon atom on the organopolysiloxane.

9. The above R ５ 9. The branched organopolysiloxane of claim 8, wherein is a tert-butyl group.

10. The branched organopolysiloxane according to claim 1, wherein said weight average molecular weight is 1,500 or less.

11. The branched organopolysiloxane of claim 1 having a cage-like molecular structure.

12. The branched organopolysiloxane of claim 1, wherein said polydispersity is 1.20 or less.

13. The branched organopolysiloxane according to claim 1, wherein R in said formula (1) is an unsubstituted or fluorine-substituted monovalent hydrocarbon group.

14. The branched organopolysiloxane according to claim 1, wherein R in said formula (1) is a monovalent hydrocarbon group having 1 to 3 carbon atoms.

15. The branched organopolysiloxane according to claim 1, wherein R in said formula (1) contains a phenyl group.

16. The branched organopolysiloxane according to claim 1, wherein e in said formula (1) satisfies 0≦e≦0.

05.

17. The branched organopolysiloxane according to claim 1, having an average of 12 or less silicon atoms per molecule.

18. A branched organopolysiloxane composition comprising: (A) the branched organopolysiloxane according to any one of claims 1 to 17; (B) a photoacid generator; and (C) an organic solvent, wherein the content of component (B) is 0.1 parts by mass or more and 20 parts by mass or less per 100 parts by mass of component (A).

19. The branched organopolysiloxane composition was applied to a glass plate so that the thickness after application was 0.5 μm, and then heat-treated at 100° C. for 1 minute to prepare a coating film that did not contain the organic solvent. The coating film was then irradiated with high-energy rays containing light with a wavelength of 254 nm at a light intensity of 40 mJ / cm in terms of the amount of light at a wavelength of 254 nm. ２ 19. The branched organopolysiloxane composition according to claim 18, wherein when the composition is irradiated so as to satisfy the above condition and then heated (post-exposure bake, PEB) at 120° C. for 2 minutes, and the resulting light-irradiated coating film is immersed in a 2.38 mass % aqueous solution of tetramethylammonium hydroxide (TMAH) for 1 minute and then washed with water, the coating film comprising the branched organopolysiloxane has a mass reduction rate of 90 mass % or more, and solubility in an aqueous alkaline solution is improved by light irradiation.

20. An insulating coating agent comprising the branched organopolysiloxane composition according to claim 18.

21. A resist material comprising the branched organopolysiloxane composition according to claim 18.

22. A method of using the branched organopolysiloxane composition of claim 18 as an insulating coating layer.

23. A display device comprising a layer comprising the branched organopolysiloxane composition of claim 18.

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