JP2020169229A - Polymer, photosensitive resin composition, and semiconductor device - Google Patents

Abstract

To provide a polymer having a low dielectric constant, a resin composition containing such a polymer, and a semiconductor device provided with a cured product of the resin composition as a permanent film.SOLUTION: The polymer contains norbornene, a substituted norbornene in which a substituent is a substituted or unsubstituted linear or branched C2-10 alkyl, and maleic anhydride. The polymer has a dielectric constant of 3 or less. The 5% weight loss temperature of a cured product of the polymer obtained by heat treatment under a condition of 160°C for 90 minutes is 300°C or higher.SELECTED DRAWING: None

Description

The present invention relates to polymers, photosensitive resin compositions, and semiconductor devices. More specifically, the present invention relates to a polymer, a photosensitive resin composition for forming a permanent film containing the polymer, and a semiconductor device including a cured product of the photosensitive resin composition as a permanent film.

A resist film made of a photosensitive resin composition may be used in a circuit forming process of a semiconductor integrated circuit or the like. Examples of the technique related to such a resist film include those described in Patent Document 1. Patent Document 1 describes a photoresist composition containing an alkali-soluble resin and a photosensitizer.

JP-A-2-146045

In recent years, it has been studied to use a photosensitive resin composition as a permanent film constituting an electronic device. In this case, the photosensitive resin composition is patterned by exposure and development, and then cured to form a permanent film.

As a result of the study by the present inventor, it has been found that there is room for improvement in electrical insulation when such a permanent film is used as a surface protective film or an interlayer insulating film of a semiconductor device.

The present inventors have a low dielectric constant in the polymer obtained by introducing a specific structural unit, and when such a polymer is used as a material for producing a permanent film of a semiconductor device, the obtained permanent is obtained. We have found that the electrical insulation of the film is improved, and have reached the present invention.

According to the present invention
The structural unit (A1) represented by the formula (a1) and
The structural unit (A2) represented by the formula (a2) and
A polymer comprising the structural unit (B1) represented by the formula (b1) is provided.

（式（ａ１）において、ｎは、０、１、または２である。）

(In equation (a1), n is 0, 1, or 2.)

（式（ａ２）において、ｍは、０、１、または２であり、Ｒ_１〜Ｒ_４はそれぞれ独立して、水素原子、あるいは置換または無置換の、直鎖または分岐鎖の炭素数２〜１０のアルキルであり、ただしＲ_１〜Ｒ_４のうち少なくとも１つは、置換または無置換の、直鎖または分岐鎖の炭素数２〜１０のアルキルである。）。

(In the formula (a2), m is 0, 1, or 2, and R _{1 to} R ₄ are independently hydrogen atoms, or substituted or unsubstituted, linear or branched carbon atoms 2 to 2. It is an alkyl of 10, but at least one of R _{1 to} R ₄ is a substituted or unsubstituted, linear or branched chain alkyl having 2 to 10 carbon atoms).

Further, according to the present invention, there is provided a photosensitive resin composition for forming a permanent film containing the above polymer.

Furthermore, according to the present invention, there is provided a resin composition for forming an insulating layer of a rewiring layer containing the above polymer.

Furthermore, according to the present invention
With semiconductor chips
A rewiring layer having an insulating layer provided on the surface of the semiconductor chip is provided.
Provided is a semiconductor device in which the insulating layer in the rewiring layer is composed of a cured product of the resin composition.

According to the present invention, there is provided a semiconductor device including a polymer having a low dielectric constant, a resin composition containing such a polymer, and a cured product of the resin composition as a permanent film.

Hereinafter, embodiments of the present invention will be described.

(Polymer P)
The polymer of the present embodiment (hereinafter referred to as "polymer P") has a structural unit (A1) represented by the formula (a1), a structural unit (A2) represented by the formula (a2), and a formula (b1). ) Is included with the structural unit (B1).

式（ａ１）において、ｎは、０、１、または２である。

In formula (a1), n is 0, 1, or 2.

式（ａ２）において、ｍは、０、１、または２であり、Ｒ_１〜Ｒ_４はそれぞれ独立して、水素原子、あるいは置換または無置換の、直鎖または分枝鎖の炭素数２〜１０のアルキルであり、ただしＲ_１〜Ｒ_４のうち少なくとも１つは、置換または無置換の、直鎖または分岐鎖の炭素数２〜１０のアルキルである。

In the formula (a2), m is 0, 1, or 2, and R _{1 to} R ₄ are independently hydrogen atoms, or substituted or unsubstituted, linear or branched carbon atoms 2 to 2. It is an alkyl of 10, but at least one of R _{1 to} R ₄ is a substituted or unsubstituted, linear or branched chain alkyl having 2 to 10 carbon atoms.

The polymer P has a low dielectric constant by containing the structural units (A1), (A2) and (B1). In particular, the polymer P obtained by at least one of R _{1 to} R ₄ in the structural unit (A2) being a substituted or unsubstituted, linear or branched alkyl having 2 to 10 carbon atoms. The dielectric constant is reduced. The reason for this is not necessarily clear, but it is considered that the degree of entanglement between the polymers is appropriately suppressed by the alkyl side chain of the obtained polymer P, and the density of the polymer P is lowered.

The alkyl constituting R _{1 to} R ₄ is preferably an alkyl having 3 to 10 carbon atoms, and even more preferably an alkyl having 4 to 10 carbon atoms. Examples of the substituent that the alkyl may have include linear, branched or cyclic, saturated or unsaturated hydrocarbon groups having 1 to 6 carbon atoms, such as methyl, ethyl, propyl, phenyl and the like. Can be mentioned. Examples of alkyls that can constitute R _{1 to} R ₄ include, but are not limited to, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, phenityl and the like.

In one embodiment, the polymer P may further comprise a structural unit (B2) represented by the formula (b2). Hereinafter, the polymer P containing the structural unit (B2) is referred to as "polymer P'". The polymer P'containing such a structural unit (B2) has a low dielectric constant and a 5% weight loss temperature comparable to those of the polymer P, and has excellent alkali solubility. Therefore, the polymer P'has excellent processability in a photolithography method using an alkaline aqueous solution as a developing solution.

In the formula (b2), _{R 5} is a substituted or unsubstituted, straight or alkyl having 1 to 10 carbon atoms branched.
Substituent or unsubstituted alkyl having 1 to 10 carbon atoms constituting R ₅ includes an alkyl group, an alkenyl group, an alkynyl group, an alkylidene group, an aryl group and an aralkyl group having 1 to 10 carbon atoms. Examples include groups, alkalil groups, cycloalkyl groups, and heterocyclic groups.
Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a neopentyl group. Included are hexyl groups, heptyl groups, octyl groups, nonyl groups, and decyl groups.
Examples of the alkenyl group having 1 to 10 carbon atoms include an allyl group, a pentenyl group, and a vinyl group. Examples of the alkynyl group include an ethynyl group.
Examples of the alkylidene group having 1 to 10 carbon atoms include a methylidene group and an ethylidene group.
Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group and a naphthyl group.
Examples of the aralkyl group having 1 to 10 carbon atoms include a benzyl group and a phenethyl group.
Examples of the alkalil group having 1 to 10 carbon atoms include a tolyl group and a xsilyl group. Examples of the cycloalkyl group having 1 to 10 carbon atoms include an adamantyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group.
Examples of the heterocyclic group include an epoxy group and an oxetanyl group.

Properties such as the dielectric constant and heat resistance of the polymer P depend on the type and amount of the structural unit contained in the polymer P or the polymer P'. The ratio of the structural unit (A1) in the total structural units of the polymer P is preferably 10 mol% or more and 40 mol% or less, and more preferably 15 mol% or more and 35 mol% or less. The ratio of the structural unit (A2) in the total structural units of the polymer P or the polymer P'of the present embodiment is preferably 10 mol% or more and 40 mol% or less, and more preferably 15 mol% or more and 35 mol. % Or less. The ratio of the structural unit (B1) in the total structural units of the polymer P or the polymer P'is preferably 45 mol% or more and 55 mol% or less, and more preferably 49 mol% or more and 51 mol% or less. Even more preferably, it is 49.5 mol% or more and 50.5 mol% or less.

The polymer P has a low dielectric constant by containing the structural units (A1), (A2) and (B1). The relative permittivity of the polymer P of the present embodiment is preferably 3 or less, more preferably 2.9 or less. The dielectric loss tangent of the polymer P is 0.015 or less, preferably 0.01 or less, and more preferably 0.007 or less. Such a low-dielectric polymer P can be suitably used as a material for articles requiring insulation, such as a permanent film and an interlayer insulating film of a semiconductor device.

The polymer P'has a low dielectric constant and alkali solubility by containing the structural unit (B1) in addition to the structural units (A1), (A2) and (B1). The relative permittivity of the polymer P'of this embodiment is preferably 3.3 or less, more preferably 3.1 or less, and even more preferably 2.9 or less. The dielectric loss tangent of the polymer P'is 0.04 or less, preferably 0.035 or less, and more preferably 0.03 or less. Such a low-dielectric polymer P'can be suitably used as a material for articles such as permanent films and interlayer insulating films of semiconductor devices, which are produced by a photolithography method and are required to have insulating properties.

In the polymer P', the ratio of the structural unit (A1) in the total structural units of the polymer P'is preferably 10 mol% or more and 40 mol% or less, and more preferably 15 mol% or more and 35 mol% or less. is there. The ratio of the structural unit (A2) in the total structural units of the polymer P'is preferably 10 mol% or more and 40 mol% or less, and more preferably 15 mol% or more and 35 mol% or less. The ratio of the structural unit (B1) in the total structural units of the polymer P'is preferably 5 mol% or more and 20 mol% or less, and more preferably 10 mol% or more and 15 mol% or less. The ratio of the structural unit (B2) in the total structural units of the polymer P'is preferably 30 mol% or more and 45 mol% or less, and more preferably 35 mol% or more and 42 mol% or less.

Further, the polymer P or the polymer P'contains the above structural units (A1), (A2) and (B1), so that the cured product has excellent heat resistance. For example, the 5% weight loss temperature of the cured product obtained by heat-treating the polymer P at 160 ° C. for 90 minutes can be 300 ° C. or higher, preferably 310 ° C. or higher, and more preferably 320 ° C. or higher. Such polymer P or polymer P'can be suitably used as a material for articles that require heat resistance, such as a permanent resist film, a protective film, and an interlayer insulating film of a semiconductor device.

The ratio of the structural unit (B1) to the total amount (A1 + A2) of the structural unit (A1) and the structural unit (A2) in the total structural unit of the polymer P is preferably the structural unit (A1 + A2): the structural unit (B1). The (molar ratio) is 1: 1.5 to 0.9: 1, more preferably 1: 1 to 1: 1.1.

The ratio of the structural unit (A2) to the structural unit (A1) in the total structural units of the polymer P is preferably such that the structural unit (A1): the structural unit (A2) (molar ratio) is 1: 1 to 1: 5. It is more preferably 1: 1 to 1: 3.5.

The polymer P may have a lower dielectric constant and better heat resistance by including the structural units (A1), (A2) and (B2) in the above proportions.

The ratio of the total amount (B1 + B2) of the structural unit (B1) and the structural unit (B2) to the total amount (A1 + A2) of the structural unit (A1) and the structural unit (A2) in the total structural unit of the polymer P'is The structural unit (A1 + A2): the structural unit (B1 + B2) (molar ratio) is preferably 1: 1.5 to 0.9: 1, and more preferably 1: 1 to 1: 1.1.

The ratio of the structural unit (A2) to the structural unit (A1) in the total structural unit of the polymer P'is preferably that the structural unit (A1): the structural unit (A2) (molar ratio) is 1: 1 to 1: It is 5, more preferably 1: 1 to 1: 3.5.

By including the structural units (A1), (A2), (B1), and (B2) in the above proportions, the polymer P'can have a further reduced dielectric constant and improved heat resistance, and is alkaline. May have solubility.

In one embodiment, the weight average molecular weight of the polymer P or the polymer P'is preferably 1500 or more and 30,000 or less, more preferably 3000 or more and 25,000 or less. The polymer P or polymer P'having a weight average molecular weight in such a range can form an appropriate crosslinked structure, and the obtained cured polymer product can have excellent heat resistance.

The polymer P is a norbornene-type monomer (monomer A) containing norbornene represented by the formula (a1m) and a substituted norbornene represented by the formula (a2m), and maleic anhydride (monomer B) represented by the formula (b1m). Can be prepared by addition polymerization of and. The method of addition polymerization is not limited, and for example, a radical polymerization method using a radical polymerization initiator can be used.

式（ａ１ｍ）中、ｎは、式（ａ１）における定義と同義であり、
式（ａ２ｍ）中、ｍおよびＲ_１〜Ｒ_４は、式（ａ２）における定義と同義である。

In the formula (a1m), n is synonymous with the definition in the formula (a1).
Wherein (a2m), m and _R 1 to R ₄ are the same as defined in formula (a2).

The molar ratio of monomer A to monomer B used in the preparation of the polymer of the present embodiment is preferably 1: 1.5 to 0.9: 1, and more preferably 1: 1 to 1: 1.1. Is. Further, norbornene (a1m): substituted norbornene (a2m), which is the molar ratio of norbornene (a1m) and substituted norbornene (a2m) in the monomer A, is preferably 1: 1 to 1: 5, more preferably. Is 1: 1 to 1: 3.5.

The polymer P can be prepared by dissolving the monomer A, the monomer B, and the radical polymerization initiator, if necessary, in a solvent, and then heating for a predetermined time to allow the addition polymerization reaction to proceed. The heating temperature is, for example, 50 ° C. or higher and 80 ° C. or lower, and the heating time is 5 hours or longer and 20 hours or lower. In the addition polymerization reaction, an additive such as a chain transfer agent may be used to control the terminal structure of the obtained polymer.

Polymer P'can be obtained by opening the structural unit (B1) of the polymer P obtained by the addition polymerization reaction of the monomer A and the monomer B. Specifically, the polymer P'can be prepared by opening a part of the structural unit (B1) derived from maleic anhydride in the polymer P.

Here, the ring-opening of the structural unit (B1) derived from maleic anhydride and the ring-opening rate thereof can be measured as follows.
The obtained polymer P'1 mg is set in a thermogravimetric / differential thermal analyzer (for example, STA7200RV manufactured by Hitachi High-Tech Science Corporation). This is heated from 35 ° C. to 500 ° C. at a heating rate of 10 ° C./min under a nitrogen atmosphere. The rate of thermogravimetric reduction at 300 ° C. is defined as the ring opening rate.

The step of ring-opening the polymer P to obtain the polymer P'is to (i) treat the polymer P with an alcohol in the presence of a basic catalyst, or (ii) a hydroxide of an alkali metal as a base. It is carried out by treating with alcohol in the presence. Specifically, the reagent (i) or the reagent (ii) is added to the reaction mixture of the monomer A and the monomer B obtained in the polymerization step, and the mixture is stirred at 40 ° C. or higher and 90 ° C. or lower for 1 hour or more and 5 hours or less. Then, the reaction solution L1 is obtained. In the reaction solution L1, a part of the anhydrous ring of the structural unit (B1) derived from maleic anhydride of the polymer P is opened, and a part of the terminal formed by the ring opening is esterified. The remaining ends are not esterified and have a metal salt structure. The ring-opening rate of the polymer P'can be controlled by adjusting the amount of the metal alkoxide or alkali metal hydroxide used in the ring-opening step. Here, as the basic catalyst used in the treatment (i), an amine compound such as triethylamine, pyridine, or dimethylaminopyridine, or a nitrogen-containing heterocyclic compound can be used.

In the treatment (ii), the structural unit (B1) derived from maleic anhydride of the polymer P is opened by the treatment (ii) using an alcohol and an alkali metal hydroxide as a base.
As the alkali metal hydroxide, sodium hydroxide is preferable from the viewpoint of handleability.

The alcohol used in the process (i) or process (ii), 1-valent alcohol _(R 5 OH) is preferred. Here, _{R 5} is the same as _{R 5} in the formula (b2), a substituted or unsubstituted, straight or alkyl having 1 to 10 carbon atoms branched.

In this ring-opening step, a part of the structural unit (B1) derived from maleic anhydride in the polymer P has a structure represented by the following formula (b1-1). Here, R ₅ has the same meaning as above.

Next, the reaction solution L1 is treated with an acidic aqueous solution such as hydrochloric acid or formic acid to replace the metal ion (Na ⁺ ) in the structural unit represented by the formula (b1-1) with a proton (H ⁺ ). As a result, the structure represented by the formula (b1-1) becomes the structural unit (B2) represented by the formula (b2), and the polymer P'is obtained.

After the ring-opening step, the obtained solution containing the polymer P'may be washed with a mixed solution of water and an organic solvent (for example, methyl ethyl ketone) to remove residual metal components.

The polymer P'can include a structural unit (B3) represented by the formula (b3) and / or a structural unit (B4) represented by the formula (b4), which can be produced by the ring-opening step and the acidic solution treatment. Here, in the formula (b3), R ₆ and R ₇ are independently substituted or unsubstituted alkyl having 2 to 10 carbon atoms in the linear or branched chain.

Polymer P'has alkali solubility by including the structural unit (B2). Therefore, the polymer P'can be suitably processed by a photolithography method using an alkaline aqueous solution as a developing solution. Further, the alkali solubility of the polymer P'can be adjusted to a desired degree by adjusting the amount of the structural unit (B2) contained therein, in other words, the ring-opening rate. The ring-opening rate of the polymer P'is preferably 75% or more and 85% or less. When having such a ring-opening rate, the polymer P'can have excellent alkali solubility and low dielectric property, and is therefore suitably used as a material for articles such as permanent films and interlayer insulating films of semiconductor devices. can do.

The alkali dissolution rate of the polymer P'can be, for example, 80 nm / sec or more and 2100 nm / sec or less. Here, the alkali dissolution rate is a polymer film obtained by applying a propylene glycol monomethyl ether acetate solution (solid content 25% by mass) of polymer P'on a silicon wafer by a spin method and soft-baking at 100 ° C. for 120 seconds. Is impregnated with a 2.38% aqueous solution of tetramethylammonium hydroxide at 23 ° C., and the time until the polymer film is visually erased is measured.

(Use)
Since the polymer P or the polymer P'of the present embodiment has low dielectric property and excellent heat resistance, for example, in order to prepare a permanent film such as a protective film for an electronic device, an interlayer insulating film, or a permanent resist film. It is preferably used as a material for producing an insulating layer for a rewiring layer.

In one embodiment, a resin composition comprising polymer P or polymer P'is provided as a material for forming a permanent film. In this case, the resin composition is provided as a varnish-like composition in which the polymer P or polymer P', the cross-linking agent and the photosensitizer, and optionally other additives are dissolved in a solvent.

The cross-linking agent used in the resin composition is not limited as long as it is a compound containing a functional group that reacts with the polymer P or the polymer P', but is selected from the group consisting of a glycidyl group, an oxetanyl group and a blocked isocyanate group as an example. Examples include compounds containing one or more of them.

As the photosensitizer used in the resin composition, a diazoquinone compound can be used when producing a positive photosensitive resin composition. Further, when producing a negative type photosensitive resin composition, a photoacid generator can be used as the photosensitizer. As any of these photosensitizers, compounds known in the art can be used.

Examples of the solvent used in the resin composition include N-methyl-2-pyrrolidone, γ-butyrolactone, N, N-dimethylacetamide, dimethylsulfoxide, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, and propylene glycol monomethyl ether. Dipropylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl lactate, ethyl lactate, butyl lactate, methyl-1,3-butylene glycol acetate, 1,3-butylene glycol-3-monomethyl ether, methyl pyruvate, and pyruvate. Examples thereof include ethyl and methyl-3-methoxypropionate.

The method for preparing the resin composition in the present embodiment is not limited, and it can be prepared by using a conventionally known method. For example, each of the above components can be prepared by mixing and dissolving in a solvent. Thereby, a varnish-like resin composition can be obtained.

The resin composition of the present embodiment can be applied to a substrate and then cured by heat treatment to form a resin film. The obtained resin film has a low dielectric constant and excellent heat resistance due to the polymer P or the polymer P'contained therein. Therefore, such a resin film can be suitably used as a protective film for an electronic device, an interlayer insulating film, or a permanent film such as a permanent resist film, particularly as an insulating layer for a rewiring layer.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than the above can be adopted.

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

(Examples A1 to A5, Comparative Example A1)
In an appropriate reaction vessel, in the amounts shown in Table 1, norbornene, substituted norbornene, and maleic anhydride as raw material monomers, and dimethyl azobisisobutyrate as a polymerization initiator (“V” manufactured by Wako Pure Chemical Industries, Ltd.) -601 ") 1.54 g and 49.3 g of methyl ethyl ketone (MEK) as a solvent were added, and the mixture was stirred and dissolved. Then, after removing the dissolved oxygen in the system by nitrogen bubbling, the mixture was heated and reacted at an internal temperature of 65 ° C. for 6 hours. The reaction mixture was then cooled to room temperature. The diluted solution was poured into a large amount of methanol to precipitate the polymer. Then, the polymer was collected by filtration, washed with methanol, and vacuum dried at 120 ° C. for 16 hours to obtain a polymer P. The formation of the polymer P and the composition of the structural units constituting the polymer P were confirmed by analyzing the polymer P by gas chromatography (gas chromatography device GC-2030 manufactured by SHIMADZU) and measuring the amount of residual monomers. .. As for the composition of the polymer P, the amount of the monomer obtained by subtracting the amount of the residual monomer from the amount of the monomer charged was defined as the composition ratio of the structural unit constituting the polymer P.

(Examples B1 to B5, Comparative Example B1)
In an appropriate reaction vessel, add norbornene, substituted norbornene, and maleic anhydride, 1.54 g of V-601 (polymerization initiator), and 49.3 g of methyl ethyl ketone (MEK) in the amounts shown in Table 1, and stir. It was dissolved. Then, after removing the dissolved oxygen in the system by nitrogen bubbling, the mixture was heated and reacted at an internal temperature of 65 ° C. for 6 hours. The reaction mixture was then cooled to room temperature. The diluted solution was poured into a large amount of methanol to precipitate the polymer. Then, the polymer was collected by filtration, washed with methanol, and vacuum dried at 120 ° C. for 16 hours to obtain a polymer P.
5 g of the obtained polymer P was dissolved in 25 g of butyl alcohol. Then, 2 g of triethylamine was added, and the mixture was reacted at 85 ° C. for 6 hours. The resulting reaction mixture was cooled to room temperature and then neutralized with formic acid. The reaction mixture was poured into a large amount of pure water to precipitate the polymer. The obtained polymer was collected by filtration, washed with pure water, and then dried to obtain a polymer P'.

The alkyl-substituted norbornenes listed in Table 1 are as follows.
(Replacement norbornene)
-Substituted norbornene 1: 5-n-butylbicyclo [2.2.1] hept-2-ene-substituted norbornene 2: 5-hexylbicyclo [2.2.1] hept-2-ene-substituted norbornene 3: 5 -Desilbicyclo [2.2.1] hept-2-ene / substituted norbornene 4: 5-phenethylbicyclo [2.2.1] hept-2-ene

(Evaluation of polymer P)
The polymers P obtained in Example A and Comparative Example A were evaluated for the following items.

<Electrical insulation>
The electrical insulation of the polymer P was evaluated using the relative permittivity and the dielectric loss tangent as indexes. The measurement method is as follows.
-Relative permittivity, dielectric loss tangent Aluminum was vapor-deposited on the wafer substrate, polymer P was applied to the surface by a spin coating method to a thickness of 2 to 3 um, and dried at 100 ° C. for 120 seconds. Then, aluminum was deposited on the surface of the polymer P. A test piece was obtained by using the aluminum film on the wafer electrode as the main electrode (φ8 mm) and the aluminum on the polymer P film as the counter electrode (φ10 mm). The relative permittivity of this test piece was measured under the condition of 10 KHz using an LCR meter (precision LCR meter HP4284A manufactured by Agilent Technologies, Inc.). The dielectric loss tangent was obtained from the relative permittivity.

<Heat resistance>
The heat resistance of the polymer P was evaluated using the 5% weight loss temperature as an index. The measurement method is as follows.
-5% Weight loss temperature The obtained polymer P'1 mg was set in a thermogravimetric / differential thermal analyzer (STA7200RV, manufactured by Hitachi High-Tech Science Corporation). This was heated from 35 ° C. to 500 ° C. at a heating rate of 10 ° C./min under a nitrogen atmosphere. At this time, the temperature at which the thermal weight reduction of 5% occurs with respect to the weight of the set polymer P'was read.
The results are shown in Table 1.

(Evaluation of polymer P')
The polymers P'obtained in Example B and Comparative Example B were evaluated for the following items.

<Electrical insulation>
The electrical insulation of the polymer P'was evaluated using the relative permittivity and the dielectric loss tangent as indexes. The measuring method is as described above.

<Alkaline solubility>
The alkali solubility of the polymer P'was evaluated using the alkali dissolution rate as an index. The measuring method is as described above.
-Alkali dissolution rate Polymer P'was dissolved in propylene glycol monomethyl ether acetate to prepare a solution having a solid content concentration of 25%. This polymer solution was applied onto a silicon wafer by a spin method and soft-baked at 100 ° C. for 120 seconds to form a polymer film having a thickness H of about 2.0 μm. The silicon wafer on which the polymer film was formed was impregnated with a 2.38% aqueous solution of tetramethylammonium hydroxide at 23 ° C., and the time T until the polymer film was visually erased was measured. From H and T, the alkali dissolution rate was calculated from the following formula.
(Alkali dissolution rate) [nm / sec] = (film thickness H) / (time T until the polymer film disappears)
The results are shown in Table 2 below.

Claims (8)

The structural unit (A1) represented by the formula (a1) and
The structural unit (A2) represented by the formula (a2) and
A polymer containing the structural unit (B1) represented by the formula (b1).

(In equation (a1), n is 0, 1, or 2.)

(In the formula (a2), m is 0, 1, or 2, and R _{1 to} R ₄ are independently hydrogen atoms, or substituted or unsubstituted, linear or branched carbon atoms 2 to 2. It is an alkyl of 10, but at least one of R _{1 to} R ₄ is a substituted or unsubstituted, linear or branched chain alkyl having 2 to 10 carbon atoms).

The structural unit (A1) is 10 mol% or more and 40 mol% or less with respect to the entire structural unit constituting the polymer.
The structural unit (A2) is 10 mol% or more and 40 mol% or less with respect to the entire structural unit constituting the polymer.
The structural unit (B1) is 45 mol% or more and 55 mol% or less with respect to the entire structural unit constituting the polymer.
The polymer according to claim 1. The polymer according to claim 1 or 2, further comprising a structural unit (B2) represented by the formula (b2).

(In the formula (b2), _{R 5} is a substituted or unsubstituted, straight or alkyl having 1 to 10 carbon atoms branched.). The polymer according to claim 1 or 2, wherein the relative permittivity is 3 or less. The polymer according to any one of claims 1 to 4, wherein the cured product of the polymer obtained by heat treatment at 160 ° C. for 90 minutes has a 5% weight loss temperature of 300 ° C. or higher. A resin composition for forming a permanent film, which comprises the polymer according to any one of claims 1 to 5. A resin composition for forming an insulating layer of a rewiring layer, which comprises the polymer according to any one of claims 1 to 5. With semiconductor chips
A rewiring layer having an insulating layer provided on the surface of the semiconductor chip is provided.
A semiconductor device in which the insulating layer in the rewiring layer is composed of a cured product of the resin composition according to claim 7.