KR102285023B1 - Precursor polymer containing benzyl alcohol group, insulation layer formed from the same and method of forming insulation layer using the same - Google Patents

Abstract

Embodiments of the present invention provide a precursor polymer including a benzyl alcohol group as at least one of an end capping group and a linker group, and having a polyamic acid or polyhydroxy amide structure. A polymer structure with improved mechanical properties may be formed by crosslinking the benzyl alcohol group.

Description

A precursor polymer containing a benzyl alcohol group, an insulating film formed therefrom, and a method for forming an insulating film using the same

The present invention relates to a precursor polymer containing a benzyl alcohol group, an insulating film formed therefrom, and a method for forming an insulating film using the same.

In recent years, in the field of electronic devices such as semiconductor devices and display devices, as critical dimensions of patterns gradually decrease, a high-resolution structure is being implemented.

For example, as the line and space (L/S) of wirings included in a semiconductor device such as an interconnection line and a bit line decreases and the height also decreases, the wiring may collapse or thermally damaged even by a slight external impact. can occur For example, when the curing temperature of the organic insulating film covering the wiring increases or curing shrinkage occurs, the wiring may also be damaged.

In addition, as a flexible display device has recently been developed, a substrate or an insulating structure of a display panel is formed of an organic insulating film having flexibility. During the high-temperature curing process for forming the organic insulating layer, circuit structures included in the display device may be thermally damaged.

Polyimide or polybenzoxazole is employed as the material for the organic insulating film, and a low-temperature curing process needs to be performed in order to prevent thermal damage to the above-described wiring and substrate. Therefore, for example, it is necessary to apply a polyimide or polybenzoxazole or a precursor structure thereof having desired elasticity, chemical resistance, and hardness even through a low temperature curing of 250° C. or less.

For example, Korean Patent Application Laid-Open No. 10-2016-0063715 discloses a polyimide manufacturing method using a water-soluble polyamic acid, but there is a limit in implementing sufficient low-temperature curing properties.

Korean Patent Publication No. 10-2016-0063715

One object of the present invention is to provide a benzyl alcohol group-containing precursor polymer having improved curability and reliability.

One object of the present invention is to provide an insulating film formed from the benzyl alcohol group-containing precursor polymer and having an improved degree of curing and reliability.

One object of the present invention is to provide a method of forming an insulating film using the benzyl alcohol group-containing precursor polymer.

1. A precursor polymer comprising a benzyl alcohol group as at least one of an end capping group and a linker group, and having a polyamic acid or polyhydroxy amide structure.

2. The precursor polymer according to 1 above, wherein the benzyl alcohol group is provided as the linker group, and is derived from a compound represented by the following formula (1):

[Formula 1]

(In Formula 1, Ar ₁ is an aromatic hydrocarbon group having 6 to 12 carbon atoms).

3. The precursor polymer according to 2 above, wherein the benzyl alcohol group is derived from a compound of Formula 1-1 or 1-2 below:

[Formula 1-1]

[Formula 1-2]

.

.

4. The precursor polymer according to 1 above, wherein the benzyl alcohol group is provided as the end capping group, and is derived from a compound represented by the following Chemical Formula 2:

[Formula 2]

(In Formula 2, Ar ₂ is an aromatic hydrocarbon group having 6 to 12 carbon atoms).

5. The precursor polymer according to 4 above, wherein the benzyl alcohol group is derived from at least one selected from the group consisting of compounds of Formulas 2-1 to 2-3 below:

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

.

.

6. The precursor polymer according to the above 1, comprising a polyamic acid structure represented by the following formula (3):

[Formula 3]

(In Formula 3, Ar ₁ and Ar ₂ are aromatic hydrocarbon groups having 6 to 12 carbon atoms, R ₁ is a divalent organic _{group including an aromatic group, R 2} is a tetravalent organic group including an aromatic group, n1 and n2 is a natural number from 1 to 10,000, respectively).

7. The precursor polymer according to the above 6, which is provided as a polyimide precursor.

8. The precursor polymer according to the above 1, comprising a polyhydroxy amide structure represented by the following formula (4):

[Formula 4]

(In Formula 4, Ar ₁ and Ar ₂ are an aromatic hydrocarbon group having 6 to 12 carbon atoms, R ₃ is a tetravalent organic _{group including an aromatic group, R 4} is a divalent organic group including an aromatic group, n1 and n2 is a natural number from 1 to 10,000, respectively).

9. The precursor polymer according to 8 above, which is provided as a polybenzoxazole precursor.

10. Forming a coating film by coating the composition comprising the precursor polymer of any one of 1 to 9 on a substrate; and

Including the step of curing the coating film at a temperature of 100 to 200 ℃, the insulating film forming method.

11. An insulating film comprising a polyimide structure or a polybenzoxazole structure in which the precursor polymer of any one of 1 to 9 above is cured.

12. The insulating film according to 11 above, which is used as a substrate of a display device or a wiring protective film of a semiconductor device.

The precursor polymer according to embodiments of the present invention is provided as, for example, a polyimide precursor or a polybenzoxazole precursor, and may include a benzyl alcohol group at the end of the precursor polymer or in a repeating unit of the polymer.

The benzyl alcohol group may be provided as an additional cross-linking site through a curing process to be imidized or benzoxazole-formed inside the precursor polymer, and networking may be formed between the polymers. Therefore, even if the curing process is performed at a relatively low temperature, mechanical properties such as a sufficient degree of curing, hardness, and elasticity may be secured.

It is applied to a semiconductor device or a display device using the precursor polymer, and an insulating film having an improved degree of curing, elasticity, and chemical resistance can be formed even through low-temperature curing.

Embodiments of the present invention provide a precursor polymer that includes an end capping group or a linker group containing a benzyl alcohol group and capable of forming a polyimide or polybenzoxazole-based network structure through a low temperature curing process. In addition, an insulating film formed using the precursor polymer and a method for forming the same are provided.

Hereinafter, embodiments of the present invention will be described in detail.

< benzyl alcohol group Precursor polymer containing>

As used herein, the term “precursor polymer” may refer to a compound that has a polymer structure and is provided as a precursor that is converted into another polymer structure through additional crosslinking or curing. The precursor polymer provided through the embodiments of the present invention may be provided as a precursor of polyimide or polybenzoxazole.

In some embodiments, when the precursor polymer is provided as a polyimide precursor, the precursor polymer may include a polyamic acid structure. In some embodiments, when the precursor polymer is provided as a polybenzoxazole precursor, the precursor polymer may include a polyhydroxy amide structure.

In example embodiments, the precursor polymer may contain a benzyl alcohol group. The benzyl alcohol group may be included as an end capping group and/or a linker group of the precursor polymer.

The benzyl alcohol group may include an amine group. When the benzyl alcohol group is included as a linker group of the precursor polymer, the benzyl alcohol group may be included in the repeating unit of the precursor polymer. In this case, the benzyl alcohol group may be derived from a benzyl alcohol group-containing diamine compound.

The benzyl alcohol group-containing diamine compound may include, for example, a compound represented by Formula 1 below.

[Formula 1]

In Formula 1, Ar ₁ may be an aromatic hydrocarbon group having 6 to 12 carbon atoms. The aromatic hydrocarbon group may include a structure in which two benzene rings are bonded.

For example, the diamine compound may include a compound represented by the following Chemical Formula 1-1 or 1-2.

[Formula 1-1]

[Formula 1-2]

In the case of Formula 1-2, preferably, amine groups may be bonded to a hydroxyl group and a meta position. In this case, the diamine compound may include a compound of Formula 1-2-1 below.

[Formula 1-2-1]

When the amine groups are bonded in an ortho position, the diamine compound may not substantially participate in the reaction with the monomers of the precursor polymer due to steric hindrance with the hydroxyl group. When the amine groups are bonded to the para position, the reactivity of the diamine compound may be excessively increased, thereby inhibiting the polymerization reaction of the monomers of the precursor polymer.

When the benzyl alcohol group serves as an end capping group of the precursor polymer, the benzyl alcohol group may be derived from a benzyl alcohol group-containing monoamine compound.

For example, the benzyl alcohol group-containing monoamine compound may be represented by Formula 2 below.

[Formula 2]

In Formula 2, Ar ₂ may be an aromatic hydrocarbon group having 6 to 12 carbon atoms. Preferably, the monoamine compound may include at least one of compounds represented by the following Chemical Formulas 2-1 to 2-3.

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

When the benzyl alcohol group serves as an end capping group of the precursor polymer, the benzyl alcohol group-containing monoamine compound may act as a molecular weight regulator of the precursor polymer.

In some exemplary embodiments, the precursor polymer containing a benzyl alcohol group is provided as a polyimide precursor including a polyamic acid structure, and may be represented by, for example, Chemical Formula 3 below. As shown in Formula 3, the benzyl alcohol group may be included as an end capping group and a linker group of the precursor polymer, respectively.

[Formula 3]

In Formula 3, Ar ₁ and Ar ₂ are as defined in Formulas 1 and 2. R ₂ may represent a tetravalent organic group including an aromatic group. R ₁ may represent a divalent organic group including an aromatic group. n1 and n2 are natural numbers representing the number of repetitions. For example, n1 and n2 may be natural numbers from 1 to 10,000.

The unit represented by n1 represents an amic acid unit produced by bonding a diamine precursor and a diacid anhydride precursor to each other, and the unit represented by n2 may represent an amic acid unit in which a benzyl alcohol group is bonded to a linker group.

As the diamine precursor and diacid anhydride precursor, compounds commonly used in the art for synthesizing polyimide or polyamic acid may be used without particular limitation.

As a non-limiting example, the diamine precursor and the diacid anhydride precursor may include compounds represented by the following Chemical Formulas 3-1 and 3-2, respectively.

[Formula 3-1]

[Formula 3-2]

For example, when the diacid anhydride precursor includes the compound of Formula 3-2, the -CF ₃ group may act as an electron withdrawing group to promote nucleophilic attack of the diamine precursor. Therefore, it is possible to easily obtain a polyamic acid structure even at a low temperature.

In some exemplary embodiments, the precursor polymer containing a benzyl alcohol group is provided as a polybenzoxazole precursor having a polyhydroxy amide structure, and may be represented by, for example, Chemical Formula 4 below. As shown in Formula 4, the benzyl alcohol group may be included as an end capping group and a linker group of the precursor polymer, respectively.

[Formula 4]

In Formula 4, Ar ₁ and Ar ₂ are as defined in Formulas 1 and 2. R ₄ may represent a divalent organic group including an aromatic group. R ₃ may represent a tetravalent organic group including an aromatic group. n3 and n4 are natural numbers representing the number of repetitions. For example, n3 and n4 may be natural numbers from 1 to 10,000.

The unit denoted by n3 represents a hydroxy amide unit formed by bonding a diaminoalcohol precursor and a dicarboxylic acid precursor or a diacyl halide precursor to each other, and the unit denoted by n4 is a hydroxy amide unit in which a benzyl alcohol group is bonded to a linker group. can represent

As the diamino alcohol precursor and the diacyl halide precursor, compounds commonly used in the art for synthesizing polyhydroxy amide and polybenzoxazole may be used without particular limitation.

As a non-limiting example, the diamino alcohol precursor and the diacyl halide precursor may include compounds represented by the following Chemical Formulas 4-1 and 4-2, respectively.

[Formula 4-1]

[Formula 4-2]

The precursor polymer represented by Formula 3 may be converted into a polyimide structure through a subsequent thermal curing process. For example, an imidation reaction may proceed by dehydration condensation between adjacent carboxyl groups and amine groups within units represented by n1 and n2 of Formula 3 to form a polyimide structure.

The precursor polymer represented by Formula 4 may be converted into a polybenzoxazole structure through a subsequent thermal curing process. For example, an oxazolation reaction may proceed by dehydration condensation between adjacent amide groups and hydroxyl groups within units represented by n3 and n4 of Formula 4 to form a polybenzoxazole structure.

Networking may be generated between different precursor polymers through the end capping group and the linker group including the benzyl alcohol group together with the imidation reaction or the oxazolation reaction. For example, steric crosslinking may be generated by polymerization between aryl rings of end capping groups, between aryl rings of end capping groups and linker groups, and/or between aryl rings of linker groups.

Accordingly, the degree of curing is further increased by additional crosslinking or networking of the polymer structure, and a sufficient curable insulating film can be formed even at a relatively low temperature.

<Insulation film and method of forming insulating film>

Embodiments of the present invention provide an insulating film formed using the above-described precursor polymer and a method of forming the insulating film.

The term “insulating film” used in the present application is used to encompass not only the layer structure, but also the insulating pattern and the insulating substrate.

According to exemplary embodiments, an insulating film coating composition including the benzyl alcohol group-containing precursor polymer may be prepared.

In some embodiments, the insulating film coating composition may include the polyimide precursor polymer represented by Formula 3 above. The polyamide precursor polymer may be formed by mixing a benzyl alcohol group-containing diamine and/or monoamine compound represented by Formula 1 or 2, a diamine precursor, and a diacid anhydride precursor in an organic solvent and inducing a solution polymerization reaction.

In some embodiments, the insulating film coating composition may include the polybenzoxazole polymer represented by Chemical Formula 4 above. The polyamide precursor polymer is prepared by mixing a benzyl alcohol group-containing diamine or monoamine compound represented by Formula 1 or 2, a diamino alcohol precursor, and a diacyl halide precursor (or dicarboxylic acid precursor) in an organic solvent, followed by a solution polymerization reaction. It can be formed by induction.

The organic solvent is, for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol methyl ether. , Propylene glycol methyl ether acetate, propylene glycol propyl ether acetate, 1-methoxy-2-propanol acetate, 1-methoxy-2-propanol, diethylene glycol dimethyl ether, ethyl lactate, toluene, xylene, methyl ethyl ketone , cyclohexanone, heptanone, γ-butyrolactone, N-methyl-2-pyrrolidone (NMP), m-cresol, and the like may be included.

In some embodiments, the insulating film coating composition may further include a catalyst for promoting imidization or oxazolation reaction. For example, the catalyst may include an organic amine such as acetic anhydride and pyridine, and an organic acid-based compound such as p-toluenesulfonic acid or hydroxybenzoic acid. When the catalyst is included, chemical imidization (or oxazolation) and thermal imidization (or oxazolation) may proceed simultaneously.

In the insulating film coating composition, the equivalent ratio of the benzyl alcohol group-containing precursor (the benzyl alcohol group-containing monoamine or diamine compound) to the total precursors mixed in the organic solvent may be about 5 to 10 mol%, the total composition The content of the organic solvent by weight may be about 50 to 95% by weight. In this case, an appropriate molecular weight of the polyimide or polybenzoxazole may be obtained, and the coating property of the composition may be improved.

After the insulating film coating composition is applied on the substrate, an insulating film including a polyimide structure or a polybenzoxazole structure may be formed through a thermal curing process. According to exemplary embodiments, the thermal curing process may include a low temperature curing process performed at a temperature of 250° C. or less, and in some embodiments, may be performed in a range of 100 to 200° C.

As described above, since additional polymer networking is formed through the benzyl alcohol group, an insulating film having sufficient hardness and elasticity can be formed even through low-temperature curing.

In example embodiments, the insulating layer may be used as a flexible substrate having flexible characteristics, such as a thin film transistor (TFT) array substrate of a display device.

For example, a preliminary substrate may be formed by coating the insulating film coating composition on a carrier substrate. Thereafter, the flexible substrate may be formed by performing the above-described low-temperature curing process on the preliminary substrate.

Thereafter, a TFT array is formed on the flexible substrate, an insulating structure covering the TFT array is formed, and the carrier substrate may be removed. In some embodiments, a sacrificial layer may be formed before applying the insulating film coating composition on the carrier substrate in order to facilitate detachment or removal of the carrier substrate.

In some embodiments, the insulating layer may be used as an insulating structure such as an interlayer insulating layer or a wiring protection layer of a semiconductor device. For example, the insulating film coating composition may be coated on a substrate of a semiconductor device on which wiring is formed, and a protective film including polyimide or polybenzoxazole may be formed through a curing process.

In one embodiment, the insulating film coating composition may further include a photoactive agent such as a photoinitiator. In this case, the insulating film coating composition may have photosensitivity, and may be patterned through exposure and development processes. In this case, the insulating layer may be patterned to selectively cover the wiring.

The photoactive agent may be a diazo naphta quinone (DNQ) or naphtoquinone diazaide (NQD)-based compound having reactivity with respect to G-line, I-line, and the like.

In addition, the insulating film coating composition may further include a crosslinking agent capable of crosslinking through a photoreaction induced from the precursor polymer and the photoactive agent. The crosslinking agent is, for example, divinylaryl, divinylalkane, phthalic anhydride, tetrahydrophthalic anhydride, nadic methyl anhydride, chloroendic anhydride, phenol-formaldehyde, hexamethylenethetamine, aryl epoxide, alkyl epoxide side etc. are mentioned. These may be used alone or in combination of two or more.

In some embodiments, after the insulating film coating composition is applied on the substrate, a first baking (eg, soft baking) process may be performed. Thereafter, an exposure process may be performed, and a second baking process (eg, post-exposure baking (PEB) or hard baking) may be performed to form the insulating layer.

Both the first and second baking processes may be low-temperature curing processes performed at a temperature of 250° C. or less (eg, 100 to 200° C.).

As described above, since the insulating film of the polyimide or polybenzoxazole structure according to the exemplary embodiments is formed through low-temperature curing, curing shrinkage of the insulating film, wiring, TFT, and mechanical and thermal damage to the insulating structure due to high-temperature curing are prevented. can be suppressed

Hereinafter, experimental examples including preferred examples and comparative examples are presented to help the understanding of the present invention, but these examples are merely illustrative of the present invention and do not limit the appended claims, It is obvious to those skilled in the art that various changes and modifications to the embodiments are possible within the scope and spirit of the invention, and it is natural that such variations and modifications fall within the scope of the appended claims.

Example and comparative example

As described below, 10 parts by weight of the precursor mixture was dissolved in 90 parts by weight of the NMP solvent and reacted slowly at room temperature for 10 hours to prepare an insulating film coating composition in which the precursor polymer was dissolved. The weight average molecular weight (Mw) of the polymer was measured as a polystyrene equivalent molecular weight using gel permeation chromatography (GPC).

Example One: polyamic acid Synthesis of structural polyimide precursor polymer

,

,

,

(8: 1.6 : 0.8 : 10 몰비율)의 중합반응으로 생성된 전구체 고분자(중량평균분자량: 12,500)

,

,

,

A precursor polymer (weight average molecular weight: 12,500) produced by polymerization of (8: 1.6: 0.8: 10 molar ratio)

,

,

,

(8: 1.6 : 0.8 : 10 몰비율)의 중합반응으로 생성된 전구체 고분자(중량평균분자량: 11,800) Example 2: Synthesis of polyimide precursor polymer of polyamic acid structure

,

,

,

A precursor polymer (weight average molecular weight: 11,800) produced by polymerization of (8: 1.6: 0.8: 10 molar ratio)

Example 3: polyhydroxy amide structural polybenzoxazole Synthesis of precursor polymers

,

,

,

(8: 1.6 : 0.8 : 10 몰비율)의 중합반응으로 생성된 전구체 고분자(중량평균분자량: 10,800)

,

,

,

Precursor polymer (weight average molecular weight: 10,800) produced by polymerization of (8: 1.6: 0.8: 10 molar ratio)

Example 4: polyhydroxy amide structural polybenzoxazole Synthesis of precursor polymers

,

,

,

(8: 1.6 : 0.8 : 10 몰비율)의 중합반응으로 생성된 전구체 고분자(중량평균분자량: 10,500)

,

,

,

A precursor polymer (weight average molecular weight: 10,500) produced by polymerization of (8: 1.6: 0.8: 10 molar ratio)

Example 5: polyamic acid Synthesis of structural polyimide precursor polymer

,

,

(9.6 : 0.8 : 10 몰비율)의 중합반응으로 생성된 전구체 고분자(중량평균분자량: 12,500)

,

,

A precursor polymer (weight average molecular weight: 12,500) produced by polymerization of (9.6: 0.8: 10 molar ratio)

Example 6: polyhydroxy amide structural polybenzoxazole Synthesis of precursor polymers

,

,

(9.6 : 0.8 : 10 몰비율)의 중합반응으로 생성된 전구체 고분자(중량평균분자량: 11,800)

,

,

A precursor polymer (weight average molecular weight: 11,800) produced by polymerization of (9.6: 0.8: 10 molar ratio)

Example 7: polyhydroxy amide structural polybenzoxazole Synthesis of precursor polymers

,

,

,

(8: 1.6 : 0.8 : 10 몰비율)의 중합반응으로 생성된 전구체 고분자(중량평균분자량: 10,300 )

,

,

,

Precursor polymer (weight average molecular weight: 10,300) produced by polymerization of (8: 1.6: 0.8: 10 molar ratio)

comparative example One: polyamic acid Synthesis of structural polyimide precursor polymer

,

,

(9.6 : 0.8: 10 몰비율)의 중합반응으로 생성된 전구체 고분자(중량평균분자량: 12,100)

,

,

A precursor polymer (weight average molecular weight: 12,100) produced by polymerization of (9.6: 0.8: 10 molar ratio)

comparative example 2: polyhydroxy amide structural polybenzoxazole Synthesis of precursor polymers

,

,

(9.6 : 0.8: 10 몰비율)의 중합반응으로 생성된 전구체 고분자(중량평균분자량: 11,900)

,

,

Precursor polymer (weight average molecular weight: 11,900) produced by polymerization of (9.6: 0.8: 10 molar ratio)

Experimental example

The insulating film coating compositions according to Examples and Comparative Examples were spin-coated on a silicon wafer, and then cured at a temperature of 200° C. for 1 hour to form a polyimide insulating film having a thickness of 1,000 Å. Physical properties of the formed polyimide insulating film were evaluated as follows, and the results are shown in Table 1 below.

(One) solvent resistance evaluation

The polyimide insulating films of Examples and Comparative Examples were immersed in NMP solvent and left for 10 hours while heating at 85° C. to check changes in the appearance of the insulating film before and after solvent treatment, and evaluated as follows.

<Determination of solvent resistance>

◎: No change in the appearance of the insulating film surface

○: Observation of some dimples on the surface of the insulating film

△: Partial damage to the surface of the insulating film, peeling observed

×: the thickness of the insulating film is reduced as a whole

(2) Elastic modulus evaluation

Using Autograph AGS-10kN manufactured by Shimadzu Corporation, the tensile modulus of elasticity of the polyimide insulating film was measured at a crosshead speed of 100 mm/min, a distance between chucks of 50 mm, and a film width of 10 mm.

(double-circle): Tensile modulus of elasticity 10 GPa or more

○: Tensile modulus of 8 GPa or more

△: tensile modulus of 5 GPa or more and less than 8 GPa

x: Tensile modulus less than 5 GPa

solvent resistance modulus of elasticity Example 1 ◎ ◎ Example 2 ◎ ◎ Example 3 ◎ ◎ Example 4 ◎ ◎ Example 5 ○ ○ Example 6 ○ ○ Example 7 ○ ○ Comparative Example 1 △ △ Comparative Example 2 × ×

Referring to Table 1, in the case of the precursor polymers in the examples containing the benzyl alcohol group according to the exemplary embodiments, significantly improved solvent resistance and elastic modulus were obtained compared to the comparative examples. In Examples 1 to 4 in which the benzyl alcohol group-containing group was included as an end capping group and a linker group, more improved elastic properties were realized.

Claims (12)

It has a polyamic acid structure represented by the following formula (3) or a polyhydroxy amide structure represented by the following formula (4),
A precursor polymer comprising a linker group including a benzyl alcohol group derived from a compound represented by Formula 1 below and an end capping group including a benzyl alcohol group derived from a compound represented by Formula 2 below:
[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

(In Formulas 1 to 4, Ar ₁ and Ar ₂ are each independently an aromatic hydrocarbon group having 6 to 12 carbon atoms,
R ₁ is a divalent organic group containing an aromatic group, R ₂ is a tetravalent organic group containing an aromatic group, n1 and n2 are each a natural number of 1 to 10,000,
R ₃ is a tetravalent organic group including an aromatic group, R ₄ is a divalent organic group including an aromatic group, and n1 and n2 are each a natural number of 1 to 10,000).
delete The method according to claim 1, wherein the linker group comprises a benzyl alcohol group derived from a compound of Formula 1-1 or 1-2, the precursor polymer:
[Formula 1-1]

[Formula 1-2]

.
delete The precursor polymer according to claim 1, wherein the end capping group comprises a benzyl alcohol group derived from at least one selected from the group consisting of compounds of Formulas 2-1 to 2-3 below:
[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

.
delete The precursor polymer according to claim 1, which is provided as a polyimide precursor.
delete The precursor polymer according to claim 1, which is provided as a polybenzoxazole precursor.
Forming a coating film by coating a composition comprising the precursor polymer of any one of claims 1, 3, 5, 7 and 9 on a substrate; and
Including the step of curing the coating film at a temperature of 100 to 200 ℃, the insulating film forming method.
An insulating film comprising a polyimide structure or a polybenzoxazole structure in which the precursor polymer of any one of claims 1, 3, 5, 7 and 9 is cured.
The insulating film according to claim 11, which is used as a substrate of a display device or a wiring protective film of a semiconductor device.