JP2008222858A - Purification method of polyimide and composition containing polyimide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a purification method of polyimide and a composition containing polyimide, capable of decreasing contraction coefficient of a film when forming the film and decreased in the content of metal impurities. <P>SOLUTION: The purification method comprises heating a solution containing polyimide and a chelating reagent and having a pH of 2-12 to decrease the content of metal impurities. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polyimide purification method and a polyimide-containing composition.

  In recent years, in the field of electronic materials, with the progress of higher integration, more functions, and higher performance, circuit resistance and capacitor capacity between wirings have increased, leading to an increase in power consumption and delay time. In particular, an increase in delay time is a major factor in reducing the signal speed of the device and the occurrence of crosstalk. Therefore, in order to reduce the delay time and speed up the device, it is necessary to reduce parasitic resistance and parasitic capacitance. It has been. As a specific measure for reducing this parasitic capacitance, an attempt has been made to cover the periphery of the wiring with a low dielectric interlayer insulating film.

  The interlayer insulating film is required to have excellent heat resistance that can withstand post-processes such as a thin film formation process, chip connection, and pinning when manufacturing a mounting substrate, and chemical resistance that can withstand a wet process. Furthermore, in recent years, Cu wiring having a resistance lower than that of Al wiring is being introduced, and along with this, planarization by CMP (Chemical Mechanical Polishing) has become common, and mechanical strength that can withstand this CMP process. Is required.

  Polyimide is widely known as an organic material having high heat resistance. Polyimide usually contains impurities derived from the mixing of metal components derived from the polymerization catalyst and metal compounds in the production process, and the stability of electrical properties such as dielectric constant characteristics can be sufficiently satisfied. It is not a thing. That is, in order to stabilize electrical properties such as dielectric constant characteristics, it is important to reduce the content of metal impurities in polyimide.

On the other hand, as a method for reducing impurities in an aromatic compound, for example, Japanese Patent Application Laid-Open No. 2002-371525 discloses a method in which formic acid is allowed to act on an aromatic compound. However, when the polyimide is treated using this method, the imide ring in the polyimide is opened by formic acid, resulting in a decrease in the imidization ratio of the polyimide. The contraction rate of the film may increase. In a polyimide film, the higher the film shrinkage rate during film formation, the greater the stress generated in the resulting film.
JP 2002-371525 A

  An object of the present invention is to provide a polyimide purification method and a polyimide-containing composition that can reduce the shrinkage ratio of a film during film formation and that have a reduced metal impurity content.

The method for purifying polyimide according to one embodiment of the present invention includes:
Heating a solution containing polyimide and a chelating agent and having a pH of 2 to 12 to reduce the content of metal impurities.

  In the polyimide purification method, the solution may have a pH of 7 or more.

  In the polyimide purification method, the solution may further include a basic compound.

  In the polyimide purification method, the chelating agent may be at least one selected from acetohydroxamic acid, dicarboxylic acid and derivatives thereof, diol and derivatives thereof, and crown ether.

  In the polyimide purification method, the polyimide may contain an alkynyl group and / or an alkynylene group.

  In the polyimide purification method, the metal impurities may include Na, Fe, and Cu.

  The polyimide-containing composition according to one embodiment of the present invention includes a polyimide having an Na, Fe, and Cu content of 100 ppb or less and an imidization ratio of 90% or more, and an organic solvent. .

  In the polyimide-containing composition, the polyimide may be obtained by the polyimide purification method.

  According to the above polyimide purification method, it is possible to suppress the opening of the imide ring by heating a solution containing polyimide and a chelating agent and having a pH of 2 to 12 to reduce the content of metal impurities. Therefore, the shrinkage rate of the film during film formation can be reduced. Furthermore, by forming a film using the polyimide obtained by the above purification method, a film with low stress and reduced metal impurity content can be obtained.

  According to the polyimide-containing composition, the polyimide contains the polyimide having an Na, Fe, or Cu content of 100 ppb or less and an imidization ratio of 90% or more, and an organic solvent. When a film is formed using the containing composition, a film with low stress and reduced metal impurity content can be obtained. Therefore, for example, in the synthesis of a polyimide raw material, even if a metal compound such as a metal catalyst is used, even if the polyimide raw material contains a large amount of metal impurities, A polyimide film having a reduced content can be produced.

  Hereinafter, a polyimide purification method and a polyimide-containing composition according to an embodiment of the present invention will be specifically described.

1. Method for Purifying Polyimide According to one embodiment of the present invention, a method for purifying polyimide is to heat a solution containing polyimide and a chelating agent (hereinafter also referred to as “specific solution”) to reduce the content of metal impurities. including.

  The pH of the specific solution is usually 2 to 12 or more, preferably 3 to 10, and more preferably 4 to 7. When the pH of the specific solution is less than 2, ring opening of the imide ring in the polyimide occurs, resulting in a decrease in the imidization rate, and as a result, the film shrinkage rate during film formation may increase.

  In the polyimide purification method according to the present embodiment, the heating temperature of the specific solution is preferably 40 to 120 ° C, more preferably 40 to 80 ° C. When the heating temperature of the specific solution exceeds 120 ° C, a ring-opening reaction may occur. On the other hand, when the heating temperature of the specific solution is less than 40 ° C, metal removal may be insufficient.

  Moreover, in the purification method of the polyimide which concerns on this embodiment, it is preferable that the heating time of a specific solution is 1 to 6 hours, and it is more preferable that it is 2 to 4 hours. When the heating time of the specific solution is less than 2 hours, metal removal may be insufficient.

  Examples of metal impurities that can be reduced by the polyimide purification method according to the present embodiment include Na, Fe, and Cu. According to the method for purifying polyimide according to this embodiment, it is possible to obtain a polyimide having an imidization ratio of 90% or more and a content of Na, Fe, and Cu reduced to 100 ppb or less.

In the present invention, the imidization ratio of polyimide can be obtained by FT-IR measurement. More specifically, in the present invention, a polyamic acid that has not undergone a dehydration ring-closing reaction is defined as a 0% imidized product (reference) having an imidization rate of 0%. And about the polyamic acid and measurement sample which have not performed dehydration ring closure reaction in FT-IR, the absorbance of -OH group stretching vibration (around 3300 cm ^-1 ) derived from polyamic acid and C = O stretching vibration as an internal standard ( The absorbance at 1725 cm ⁻¹ was measured, and the imidation ratio of the measurement sample was calculated using the following formula (1).

・・・・・（１）

(1)

1.1. Polyimide In the present embodiment, the polyimide to be purified is preferably a compound having a repeating unit represented by the following general formula (2), for example.

・・・・・（２）
（式中、Ｘは４価の有機基、Ｙは２価の有機基を表し、ｎは１以上の数を表す。）
上記一般式（２）においてＸで表される４価の有機基としては、４価の脂肪族有機基、４価の脂環族有機基、あるいは４価の芳香族有機基のいずれでもよいが、特に炭素数６〜１２０の４価の芳香族有機基が好ましい。前記４価の芳香族有機基としては、例えば、

(2)
(In the formula, X represents a tetravalent organic group, Y represents a divalent organic group, and n represents a number of 1 or more.)
The tetravalent organic group represented by X in the general formula (2) may be any of a tetravalent aliphatic organic group, a tetravalent alicyclic organic group, and a tetravalent aromatic organic group. In particular, a tetravalent aromatic organic group having 6 to 120 carbon atoms is preferable. Examples of the tetravalent aromatic organic group include:

〔式中、Ｒ^６〜Ｒ^１０は相互に同一でも異なってもよく、水素原子、アルキル基（例えば、メチル基、エチル基等）、フルオロアルキル基（例えば、トリフルオロメチル基等）またはフェニル基を示す。〕等を挙げることができる。

[Wherein R ^{6 to} R ¹⁰ may be the same or different from each other, and are a hydrogen atom, an alkyl group (eg, a methyl group, an ethyl group, etc.), a fluoroalkyl group (eg, a trifluoromethyl group, etc.) or a phenyl group. Indicates. And the like.

  The divalent organic group represented by Y in the general formula (2) may be any of a divalent aliphatic organic group, a divalent alicyclic organic group, or a divalent aromatic organic group. A divalent aromatic organic group having 6 to 120 carbon atoms is particularly preferable. Examples of the divalent aromatic organic group include:

〔式中、Ｒ^１１〜Ｒ^１６は相互に同一でも異なってもよく、水素原子、アルキル基（例えば、メチル基、エチル基等）、フルオロアルキル基（例えば、トリフルオロメチル基等）またはフェニル基を示す。〕
等を挙げることができる。また、Ｙで表される２価の有機基としては、特に低誘電率を達成するという観点からフルオレン基を含むことがより望ましい。なお、Ｘで表される４価の有機基およびＹで表される２価の有機基は、それぞれ１種以上が存在することができる。

[Wherein R ^{11 to} R ¹⁶ may be the same as or different from each other, and may be a hydrogen atom, an alkyl group (eg, a methyl group, an ethyl group, etc.), a fluoroalkyl group (eg, a trifluoromethyl group, etc.) or a phenyl group. Indicates. ]
Etc. Further, the divalent organic group represented by Y more preferably contains a fluorene group from the viewpoint of achieving a low dielectric constant. Note that one or more of the tetravalent organic group represented by X and the divalent organic group represented by Y can each exist.

  As a method for synthesizing the polyimide according to the present embodiment, various methods can be adopted and are not particularly limited. For example, tetracarboxylic acid diesters corresponding to the repeating structural units represented by the general formula (2) are used. An anhydride and a diamine compound are polycondensed in an organic solvent in the presence of an excess amount of tetracarboxylic dianhydride to obtain a polyamic acid solution, and the resulting polyamic acid is dissolved in an organic solvent. And a synthesis method for obtaining a solution of a polyimide having a carboxylic acid anhydride group by a dehydration ring-closing reaction by a thermal method or a chemical method.

  Specific examples of the tetracarboxylic dianhydride used in the above method include 2,3,2 ′, 3′-biphenyltetracarboxylic dianhydride and 2,3,3 ′, 4′-biphenyltetracarboxylic acid. Dianhydride, 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride, 9,9-bis (2,3-dicarboxyphenyl) fluorene dianhydride, 9,9-bis (3,4) -Dicarboxyphenyl) fluorene dianhydride, 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis ( 3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 9,9-bis [4- (2,3-dicarboxyphenoxy) phenyl] fluorene dianhydride 9,9-bis [4- (3 4-dicarboxyphenoxy) phenyl] fluorene dianhydride, 2,2-bis [4- (2,3-dicarboxyphenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane dianhydride And 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane dianhydride and the like.

  Specific examples of the diamine compound used in the above method include 9,9-bis (2-aminophenyl) fluorene, 9,9-bis (3-aminophenyl) fluorene, 9,9-bis (4- Aminophenyl) fluorene, 9,9-bis [4- (2-aminophenoxy) phenyl] fluorene, 9,9-bis [4- (3-aminophenoxy) phenyl] fluorene, 9,9-bis [4- ( 4-aminophenoxy) phenyl] fluorene, 2,2-bis (2-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-bis (3-aminophenyl) -1 1,1,3,3,3-hexafluoropropane, 2,2-bis (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4 -(2-A Nophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3 -Hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2'-diaminodiphenyl ether, 2,3 ' -Diaminodiphenyl ether, 2,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 2,2'-diaminobiphenyl, 2,3'-diamino Biphenyl, 2,4′-diaminobiphenyl, 3,3′-diaminobiphenyl, 3,4′-diaminobiphenyl, 4,4 ′ Diaminobiphenyl, 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl, 2,2′-diamino-4,4′-bis (trifluoromethyl) biphenyl, 2- (3-aminophenyl) ) -3′-aminobiphenyl, 2,2′-bis (3-aminophenyl) biphenyl 9,9-bis [3-phenyl-4- (4-amino-2-trifluoromethylphenoxy) phenyl] fluorene, etc. Can be mentioned.

  The organic solvent that can be used in the synthesis of the polyimide is not particularly limited as long as it is inert to the raw materials and reaction products and can dissolve them. For example, dimethylformamide, dimethylacetamide Amide solvents such as N-methylpyrrolidone; aprotic polar solvents such as dimethyl sulfoxide; phenol solvents such as phenol and cresol. These organic solvents can be used alone or in admixture of two or more.

  In the synthesis of the polyamic acid, the total concentration of the tetracarboxylic dianhydride and the diamine compound is usually 1 to 50% by mass, preferably 2 to 30% by mass with respect to the total solution weight, and usually 150 ° C. Hereinafter, the reaction is preferably performed at 0 to 120 ° C. Moreover, the temperature of the thermal imidation reaction at the time of synthesize | combining a polyimide is 50-400 degreeC normally, Preferably it is 100-350 degreeC, and the temperature of chemical imidation reaction is 0-200 degreeC normally. .

  In this embodiment, when the polyimide is synthesized by the synthesis method, at least one of the aromatic tetracarboxylic dianhydride and the aromatic diamine compound has a functional group that reacts with an amine or a dicarboxylic anhydride. And a terminal crosslinking agent having a crosslinkable group are reacted to obtain a polyamic acid oligomer of a polyimide precursor having a crosslinkable group introduced at the molecular end.

  The crosslinkable group includes, for example, an unsaturated bond (for example, a double bond or a triple bond). That is, the terminal crosslinking agent to be used has a group containing an unsaturated bond. The group containing an unsaturated bond preferably has a functional group (for example, acid anhydride, amino group) possessed by a monomer that can be used during polyimide synthesis from the viewpoint of reactivity during introduction. . Therefore, by using a terminal cross-linking agent having a group containing an unsaturated bond, a polyimide precursor polyamic acid oligomer in which a cross-linkable group containing an unsaturated bond is introduced at the molecular end can be obtained.

  Examples of the terminal crosslinking agent having a group containing a double bond include maleic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, phthalic anhydride, vinylaniline, and p-aminostyrene. Thereby, the polyamic acid oligomer of the polyimide precursor by which the terminal crosslinkable group containing a double bond was introduce | transduced into the molecule terminal can be obtained. In addition, when using maleic anhydride, it not only participates in superposition | polymerization itself but can participate in addition reaction with the polyimide of an amine terminal.

  Examples of the terminal crosslinking agent having a group containing a triple bond include propargylamine, ethynylaniline (for example, 4-ethynylaniline, 3-ethynylaniline), phenylethynylaniline (for example, 3-phenylethynylaniline), And phenylethynylphthalic anhydride (for example, 4- (2-phenylethynyl) phthalic anhydride). Thereby, the polyamic acid oligomer of the polyimide precursor by which the crosslinkable group containing a triple bond was introduce | transduced into the molecule terminal can be obtained.

  In addition, although these terminal crosslinking agents can be used individually or in combination, it is preferable to use independently from a viewpoint of controlling a crosslinking density uniformly.

  The amount of terminal crosslinking agent used (for example, the amount of phenylethynylphthalic anhydride that can react with amine (mol%)) is {(the amount of aromatic diamine compound used (mol%))-(aromatic tetracarboxylic acid). Acid dianhydride (the amount used (mol%) of phenylethynylphthalic anhydride))} × 2.

  When the terminal crosslinking agent has a functional group capable of reacting with an amine at the terminal, the amount of the terminal crosslinking agent is preferably 5 to 300 mol% based on the total amount of the aromatic tetracarboxylic dianhydride, In particular, the range of 5 to 200 mol% is more preferable. When the terminal crosslinking agent has a functional group capable of reacting with an acid anhydride at the terminal, the amount of the terminal crosslinking agent used is 5 to 200 mol%, particularly 5 to 150 mol, based on the total amount of the aromatic diamine compound. % Range is preferred.

  In the polyamic acid oligomer of the polyimide precursor of the present invention, when the ratio of the terminal cross-linking agent relative to the total amount of the aromatic diamine compound or aromatic tetracarboxylic dianhydride is less than 5 mol%, curing obtained from such a composition An object may form a large number of voids or blisters on its surface, and the mechanical properties may be significantly reduced. On the other hand, when the ratio of the terminal crosslinking agent with respect to the total amount of the aromatic diamine compound exceeds 200 mol% or when the ratio of the terminal crosslinking agent with respect to the total amount of the aromatic tetracarboxylic dianhydride exceeds 300 mol%, the resulting cured product is crosslinked. Density increases and becomes very brittle.

In this embodiment, the weight average molecular weight of the polyimide to be purified is preferably 1000 to 30,000. When the weight average molecular weight of the polyimide to be purified is larger than this range, the solubility in a solvent may be lowered.
There is a case.

  It is preferable that the density | concentration of the polyimide in a specific solution is 5-30 mass%, and it is more preferable that it is 10-20 mass%. When the concentration is less than 5% by mass, there may be a problem in film formability.

1.2. Chelating Agent and Other Components The chelating agent contained in the specific solution is preferably at least one selected from, for example, acetohydroxamic acid, dicarboxylic acid and derivatives thereof, diol and derivatives thereof, and crown ether. When the chelating agent used in the specific solution is at least one of these compounds, it is particularly effective for removing transition metals.

  Examples of the diol and derivatives thereof include catechol, pinacol, and derivatives thereof. Examples of the dicarboxylic acid and derivatives thereof include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, fumaric acid, and phthalic acid.

  The specific solution preferably further contains a basic compound. In particular, when an acidic compound such as acetohydroxamic acid or dicarboxylic acid is used as a chelating agent, the pH of the specific solution is adjusted to 2 or more, and in particular, the pH is adjusted to 4 or more by including the basic compound. be able to.

  Examples of basic compounds include methanolamine, ethanolamine, propanolamine, butanolamine, N-methylmethanolamine, N-ethylmethanolamine, N-propylmethanolamine, N-butylmethanolamine, N-methylethanolamine, N-ethylethanolamine, N-propylethanolamine, N-butylethanolamine, N-methylpropanolamine, N-ethylpropanolamine, N-propylpropanolamine, N-butylpropanolamine, N-methylbutanolamine, N- Ethylbutanolamine, N-propylbutanolamine, N-butylbutanolamine, N, N-dimethylmethanolamine, N, N-diethylmethanolamine, N, N-dipropylmethanolamine N, N-dibutylmethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, N, N-dipropylethanolamine, N, N-dibutylethanolamine, N, N-dimethylpropanolamine N, N-diethylpropanolamine, N, N-dipropylpropanolamine, N, N-dibutylpropanolamine, N, N-dimethylbutanolamine, N, N-diethylbutanolamine, N, N-dipropylbutanolamine N, N-dibutylbutanolamine, N-methyldimethanolamine, N-ethyldimethanolamine, N-propyldimethanolamine, N-butyldimethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, N-propyl Jietanau Amine, N-butyldiethanolamine, N-methyldipropanolamine, N-ethyldipropanolamine, N-propyldipropanolamine, N-butyldipropanolamine, N-methyldibutanolamine, N-ethyldibutanolamine, N -Propyldibutanolamine, N-butyldibutanolamine, N- (aminomethyl) methanolamine, N- (aminomethyl) ethanolamine, N- (aminomethyl) propanolamine, N- (aminomethyl) butanolamine, N -(Aminoethyl) methanolamine, N- (aminoethyl) ethanolamine, N- (aminoethyl) propanolamine, N- (aminoethyl) butanolamine, N- (aminopropyl) methanolamine, N- (aminopropyl) Etano Amine, N- (aminopropyl) propanolamine, N- (aminopropyl) butanolamine, N- (aminobutyl) methanolamine, N- (aminobutyl) ethanolamine, N- (aminobutyl) propanolamine, N- ( Aminobutyl) butanolamine, methoxymethylamine, methoxyethylamine, methoxypropylamine, methoxybutylamine, ethoxymethylamine, ethoxyethylamine, ethoxypropylamine, ethoxybutylamine, propoxymethylamine, propoxyethylamine, propoxypropylamine, propoxybutylamine, butoxymethyl Amine, butoxyethylamine, butoxypropylamine, butoxybutylamine, methylamine, ethylamine, propylamine, butyl Min, N, N-dimethylamine, N, N-diethylamine, N, N-dipropylamine, N, N-dibutylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tetramethylammonium hydroxide, tetraethylammonium Hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetramethylethylenediamine, tetraethylethylenediamine, tetrapropylethylenediamine, tetrabutylethylenediamine, methylaminomethylamine, methylaminoethylamine, methylaminopropylamine, methylaminobutylamine , Ethylaminomethylamine, ethylaminoethylamine, ethylaminopropylamine, ethylamine Nobutylamine, propylaminomethylamine, propylaminoethylamine, propylaminopropylamine, propylaminobutylamine, butylaminomethylamine, butylaminoethylamine, butylaminopropylamine, butylaminobutylamine, pyridine, pyrrole, piperazine, pyrrolidine, piperidine, picoline , Morpholine, methylmorpholine, diazabicycloocrane, diazabicyclononane, diazabicycloundecene, ammonia, sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide and the like. In particular, pyridine is preferable as the basic compound.

  The concentration of the chelating agent in the specific solution is preferably 0.1 to 10% by mass, and more preferably 0.5 to 5% by mass. When the concentration of the chelating agent is less than 0.1% by mass, metal removal may be insufficient.

  Examples of the solvent that can be used for the specific solution include alcohol solvents, ketone solvents, ester solvents, and ether solvents. As specific examples of these solvents, the solvents exemplified in the column of organic solvents described later are preferable, and ketone solvents such as cyclohexanone are particularly preferable.

2. Polyimide-containing composition A polyimide-containing composition according to an embodiment of the present invention includes a polyimide having an Na, Fe, and Cu content of 100 ppb or less and an imidization ratio of 90% or more, and an organic solvent. Containing.

  The total solid content concentration of the polyimide-containing composition according to this embodiment is preferably 0.1 to 20% by mass and is appropriately adjusted according to the purpose of use. When the total solid content concentration of the polyimide-containing composition according to the present embodiment is 0.1 to 20% by mass, the film thickness of the coating film is in an appropriate range, and the storage stability is more excellent. The total solid content concentration can be adjusted by concentration and dilution with an organic solvent, if necessary.

2.1. Polyimide The polyimide contained in the polyimide-containing composition according to the present embodiment is preferably one that has been purified by the polyimide purification method according to the embodiment.

2.2. Organic Solvent Examples of organic solvents that can be used in the polyimide-containing composition according to this embodiment include alcohol solvents, ketone solvents, amide solvents, ester solvents, ether solvents, aliphatic hydrocarbon solvents, and aromatics. Group hydrocarbon solvents and halogen-containing solvents.

Examples of alcohol solvents include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, t-butanol, n-pentanol, i-pentanol, 2-methylbutanol, sec -Pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n-nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, full Lil alcohol, phenol, cyclohexanol, methyl cyclohexanol, 3,3,5-trimethyl cyclohexanol, benzyl alcohol, mono-alcohol solvents such as diacetone alcohol;
Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2 Polyhydric alcohol solvents such as ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol And the like; monomethyl ether, dipropylene glycol monoethyl ether, polyhydric alcohol partial ether solvents such as dipropylene glycol monopropyl ether. These alcohol solvents may be used alone or in combination of two or more.

  Examples of ketone solvents include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-i-butyl ketone, methyl-n-pentyl ketone, ethyl-n-butyl ketone, and methyl-n-hexyl. Ketone, di-i-butyl ketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, 2-hexanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, diacetone alcohol, acetophenone, Mention may be made of ketone solvents such as fenchon. These ketone solvents may be used alone or in combination of two or more.

  Examples of amide solvents include N, N-dimethylimidazolidinone, N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N- Examples thereof include nitrogen-containing solvents such as methylpropionamide and N-methylpyrrolidone. These amide solvents may be used alone or in combination of two or more.

  As ether solvents, ethyl ether, i-propyl ether, n-butyl ether, n-hexyl ether, 2-ethylhexyl ether, ethylene oxide, 1,2-propylene oxide, dioxolane, 4-methyldioxolane, dioxane, dimethyldioxane, ethylene Glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-n-hexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether , Ethylene glycol dibutyl ether, diethylene glycol monomethyl ether, diethylene glycol Dimethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol di-n-butyl ether, diethylene glycol mono-n-hexyl ether, ethoxytriglycol, tetraethylene glycol di-n-butyl ether, propylene glycol Monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, diphenyl ether Le, can be mentioned ether solvents such as anisole. These ether solvents may be used alone or in combination of two or more.

  Examples of ester solvents include diethyl carbonate, propylene carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, sec-acetate. Butyl, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate, methyl acetoacetate , Ethyl acetoacetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n acetate -Butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, glycol diacetate, methoxy acetate Triglycol, ethyl propionate, n-butyl propionate, i-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, diethyl malonate And ester solvents such as dimethyl phthalate and diethyl phthalate. These ester solvents may be used alone or in combination of two or more.

  Examples of the aliphatic hydrocarbon solvent include n-pentane, i-pentane, n-hexane, i-hexane, n-heptane, i-heptane, 2,2,4-trimethylpentane, n-octane, i-octane, Examples thereof include aliphatic hydrocarbon solvents such as cyclohexane and methylcyclohexane. These aliphatic hydrocarbon solvents may be used alone or in combination of two or more.

  Examples of aromatic hydrocarbon solvents include benzene, toluene, xylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propyl benzene, i-propyl benzene, diethyl benzene, i-butyl benzene, triethyl benzene, di-i-propyl benzene, Aromatic hydrocarbon solvents such as n-amylnaphthalene and trimethylbenzene can be mentioned. These aromatic hydrocarbon solvents may be used alone or in combination of two or more.

  Examples of the halogen-containing solvent include halogen-containing solvents such as dichloromethane, chloroform, chlorofluorocarbon, chlorobenzene, and dichlorobenzene.

  Of these, ketone solvents such as cyclohexanone are preferred.

3. Method for Forming Film A method for forming a film (polyimide film) according to one embodiment of the present invention includes a step of applying a polyimide-containing composition according to the above embodiment to a substrate to form a coating film, and a curing treatment for the coating film. The process of giving.

  According to the method for forming a film according to the present embodiment, by including the steps of applying the polyimide-containing composition according to the embodiment to a substrate and forming a coating film, and applying a curing treatment to the coating film, A film having a low shrinkage during film formation and a low content of metal impurities (Na, Fe, Cu) can be obtained.

Examples of the substrate on which the polyimide-containing composition is applied include Si-containing layers such as Si, SiO ₂ , SiN, SiC, and SiCN. As a method of applying the polyimide-containing composition to the substrate, a coating means such as spin coating, dipping method, roll coating method, spray method or the like is used. After apply | coating a polyimide containing composition to a board | substrate, a solvent is removed and a coating film is formed. In this case, as a dry film thickness, a coating film having a thickness of 0.05 to 2.5 μm can be formed by one coating and a thickness of 0.1 to 5.0 μm can be formed by two coatings. Then, the polyimide film which concerns on this embodiment can be formed by performing a hardening process with respect to the obtained coating film.

  Examples of the curing treatment include heating, irradiation with high energy rays such as electron beams and ultraviolet rays, plasma treatment, and combinations thereof, and heat treatment or irradiation with high energy rays is preferable.

  In the case of curing by heating, the coating film is heated to 80 to 450 ° C. (preferably 300 ° C. to 450 ° C.) under an inert atmosphere or reduced pressure. As a heating method at this time, a hot plate, an oven, a furnace, or the like can be used, and a heating atmosphere can be performed under an inert atmosphere or under reduced pressure.

  Moreover, in order to control the curing rate of the coating film, it can be heated stepwise or an atmosphere such as nitrogen, air, oxygen, or reduced pressure can be selected as necessary. By such a process, a polyimide film can be manufactured.

4). Polyimide film A polyimide film according to an embodiment of the present invention is excellent as an interlayer insulating film for semiconductor elements such as LSI, system LSI, DRAM, SDRAM, RDRAM, and D-RDRAM, and is also used as an etching stopper film and semiconductor element. It can be suitably used for a protective film such as a surface coat film, an intermediate layer in a semiconductor manufacturing process using a multilayer resist, an interlayer insulating film of a multilayer wiring board, a protective film for a liquid crystal display element, an insulating film, and the like. The polyimide film according to the present embodiment is useful for a semiconductor device including a copper damascene process.

  The polyimide film according to this embodiment is excellent in insulating film characteristics such as mechanical characteristics.

5. EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to the following examples. In the examples and comparative examples, “parts” and “%” indicate parts by weight and mass%, respectively, unless otherwise specified.

5.1. Evaluation method Various evaluations were performed as follows. Table 1 shows the metal impurity content and polyimide imidation ratio of the polyimide-containing compositions obtained in Examples and Comparative Examples described later.

5.1.1. Content of metal impurities The content of metal impurities in polyimide is determined by atomic absorption spectrometry (apparatus:
Measured with Hitachi Polarized Zeeman Atomic Absorption Spectrometer. Here, the content of metal impurities in the polyimide obtained by removing the solvent from the polyimide-containing composition obtained in each Example and Comparative Example was measured.

5.1.2. Imidization rate The imidation rate was calculated by the method described above by measuring an infrared absorption spectrum (apparatus: FT-IR, Digilab Japan).

5.1.3. pH
The pH of the solution was measured with a METTLER TOLEDO pH meter.

5.2. Synthesis of polyimide 5.2.1. Synthesis example 1
In a flask, 63 g of 2,2 ′, 3,3′-biphenyltetracarboxylic anhydride, 99.5 g of 9,9′-bis (4-aminophenyl) fluorene, and 35 g of phenylethynylphthalic anhydride were added to dimethylacetamide. After dissolving in 460 g, the mixture was stirred at room temperature for 2 hours. Next, 271.5 g of acetic anhydride, 197 g of pyridine, and 230 g of dimethylacetamide were added, followed by stirring overnight or longer. Next, the obtained solution was added to 2000 g of methanol to precipitate a solid content, and then the solid was dried to obtain 88.9 g of polyimide represented by the following formula (3).

・・・・・（３）
（式中、ｎは１以上の数を表す。）

(3)
(In the formula, n represents a number of 1 or more.)

5.3. Purification of polyimide (Examples 1 to 4 and Comparative Examples 1 and 2)
5.3.1. Example 1
After 5 g of the polyimide obtained in Synthesis Example 1 and 1 g of acetohydroxamic acid were dissolved in cyclohexanone to make a 100 g solution, this solution was heated to 60 ° C. and stirred for 3 hours. The pH of this solution was 4.16. Next, this solution was cooled to room temperature, 200 g of cyclohexanone was further added, 100 g of water was added, shaken and mixed, and then allowed to stand to separate into an organic phase and an aqueous phase. The organic phase was taken out and concentrated to obtain 50 g of the polyimide-containing composition of Example 1.

5.3.2. Example 2
After 5 g of the polyimide obtained in Synthesis Example 1, 1 g of acetohydroxamic acid, and 2.5 g of pyridine were dissolved in cyclohequinone to obtain a 100 g solution, this solution was heated to 60 ° C. and stirred for 3 hours. The pH of this solution was 5.72. Next, this solution was cooled to room temperature, 200 g of cyclohexanone was further added, 100 g of water was added, shaken and mixed, and then allowed to stand to separate into an organic phase and an aqueous phase. The organic phase was taken out and concentrated to obtain 50 g of the polyimide-containing composition of Example 2.

5.3.3. Example 3
5 g of polyimide obtained in Synthesis Example 1 and 1 g of catechol were dissolved in cyclohexanone to make a 100 g solution, and the solution was heated to 60 ° C. and stirred for 3 hours. The pH of this solution was 5.14. Next, this solution was cooled to room temperature, 200 g of cyclohexanone was further added, 100 g of water was added, shaken and mixed, and then allowed to stand to separate into an organic phase and an aqueous phase. The organic phase was taken out and concentrated to obtain 50 g of the polyimide-containing composition of Example 3.

5.3.4. Example 4
After 5 g of the polyimide obtained in Synthesis Example 1, 1 g of oxalic acid, and 5.5 g of pyridine were dissolved in cyclohequinone to obtain a 100 g solution, this solution was heated to 60 ° C. and stirred for 3 hours. The pH of this solution was 5.72. Next, this solution was cooled to room temperature, 200 g of cyclohexanone was further added, 100 g of water was added, shaken and mixed, and then allowed to stand to separate into an organic phase and an aqueous phase. The organic phase was taken out and concentrated to obtain 50 g of the polyimide-containing composition of Example 4.

5.3.5. Comparative Example 1
The polyimide-containing composition of Comparative Example 1 was obtained by dissolving 5 g of the polyimide obtained in Synthesis Example 1 in 95 g of cyclohexanenon. The pH of this solution was 5.35.

5.3.6. Comparative Example 2
After 5 g of the polyimide obtained in Synthesis Example 1 and 1 g of oxalic acid were dissolved in cyclohequinone to obtain a 100 g solution, this solution was heated to 60 ° C. and stirred for 3 hours. The pH of this solution was 1.11. Next, this solution was cooled to room temperature, 200 g of cyclohexanone was further added, 100 g of water was added, shaken and mixed, and then allowed to stand to separate into an organic phase and an aqueous phase. The organic phase was taken out and concentrated to obtain 50 g of the polyimide-containing composition of Comparative Example 2.

5.4. Consideration of results According to Table 1, since the polyimide-containing compositions obtained in Examples 1 to 4 were obtained by heating a solution containing polyimide and a chelating agent, the imidization ratio of polyimide was determined. It can be understood that the respective contents of metal impurities (Na, Fe, Cu) in the polyimide could be reduced to 100 ppb or less while maintaining.

  On the other hand, since the polyimide-containing composition obtained in Comparative Example 1 was not subjected to the heat treatment, it can be understood that the content of metal impurities (Na, Fe, Cu) is 1000 ppb or more. Moreover, since the polyimide containing composition obtained by the comparative example 2 heated on acidic conditions, the imidation ratio of the polyimide fell to less than 90%.

Claims (7)

  A method for purifying polyimide, comprising heating a solution containing polyimide and a chelating agent and having a pH of 2 to 12 to reduce the content of metal impurities. In claim 1,
The method for purifying polyimide, wherein the solution further contains a basic compound. In claim 1 or 2,
The method for purifying polyimide, wherein the chelating agent is at least one selected from acetohydroxamic acid, dicarboxylic acid and derivatives thereof, diol and derivatives thereof, and crown ether. In any one of Claims 1-3,
The polyimide is a method for purifying polyimide, wherein the polyimide contains an alkynyl group and / or an alkynylene group. In any one of Claims 1-4,
The method for purifying polyimide, wherein the metal impurities include Na, Fe, and Cu. A polyimide having a Na, Fe, or Cu content of 100 ppb or less and an imidization ratio of 90% or more;
An organic solvent,
A polyimide-containing composition containing In claim 6,
The said polyimide is a polyimide containing composition obtained by the purification method of the polyimide in any one of Claims 1-5.