JP2004026850A - Polyimide, polyamic acid, and interlayer insulation film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyimide, a polyamic acid, and an interlayer insulation film using these particularly polyimide which excels in adhesion with various substrates, has superior heat resistance and low dielectric characteristics, and is optimum as the interlayer insulation film in LSI(large scale integrated circuit); the polyamic acid as a precursor which can form the polyimide; and the interlayer insulation film which comprises the polyimide. <P>SOLUTION: The polyimide is composed of a recurring unit represented by formula (1) (wherein X indicates a tetravalent cyclic aliphatic group). <P>COPYRIGHT: (C)2004,JPO

Description

（式中、Ｘは４価の環状脂肪族基を示し、Ｙはアダマンタン構造を有する２価の芳香族基を示す。）
一般式（２）
【化６】

（式中、Ｘは４価の環状脂肪族基を示す）
一般式（３）
【化７】

（式中、Ｘは４価の環状脂肪族基を示し、Ｙはアダマンタン構造を有する２価の芳香族基を示す。）
一般式（４）
【化８】

（式中、Ｘは４価の環状脂肪族基を示す）
【０００９】
本発明のポリアミック酸はアダマンタン構造を有する芳香族ジアミン化合物と環状脂肪族テトラカルボン酸二無水物とを有機溶媒中で重縮合させることにより製造することができる。
アダマンタン構造を有する芳香族ジアミン化合物としては、１，３−ビス（４−アミノフェニル）アダマンタン、１，３−ビス［４−（４−アミノフェノキシ）フェニル］アダマンタン（一般式（５））、１，６−ビス（４−アミノフェニル）ジアマンタン、１，６−ビス［４−（４−アミノフェノキシ）フェニル］ジアマンタン、４，９−ビス（４−アミノフェニル）ジアマンタン、４，９−ビス［４−（４−アミノフェノキシ）フェニル］ジアマンタン、３，３’−ビス［４−（３−アミノフェノキシ）フェニル］−１，１’−ビアダマンタン、３，３’−ビス［４−（４−アミノフェノキシ）フェニル］−１，１’−ビアダマンタンなどを挙げることができる。
一般式（５）
【化９】

【００１０】
環状脂肪族テトラカルボン酸二無水物としては、１，２，３，４−シクロブタンテトラカルボン酸二無水物、ビシクロ［２．２．２］オクト−７−エン−２，３，５，６−テトラカルボン酸二無水物、ビシクロ［２．２．１］ヘプタン−２−メタンカルボン酸二無水物、１，２，３，４−シクロブタンテトラカルボン酸二無水物、２，３，５−トリカルボキシ酢酸二無水物、ビシクロ［２．２．１］ヘプタン−２，３，５，６−テトラカルボン酸二無水物、ビシクロ［２．２．１］ヘプタン−２，３，５−トリカルボキシ酢酸二無水物、ビシクロ［２．２．２］オクト−７−エン−２，３，５，６−テトラカルボン酸二無水物、ビシクロ［２．２．２］オクト−７−エン−２，３，５，６−テトラカルボン酸二無水物、５−（２，５−ジオキソテトラヒドロフルフリル）−３−メチル−３−シクロヘキセン−１，２−ジカルボン酸無水物、３−オキサビシクロ［３．２．１］オクタン−２，４−ジオン−６−スピロ−３‘−（テトラヒドロフラン−２’，５‘−ジオン）、デカヒドロ−１，４，５，８−ジメタノナフタレン−２，３，６，７−テトラカルボン酸二無水物などを挙げることができる。
アダマンタン構造を有する芳香族ジアミン化合物および環状脂肪族テトラカルボン酸二無水物とはほぼ等モルずつ反応させ、反応温度は５０〜９０℃程度である。
【００１１】
なお、上記製造条件を適宜調節することにより、ポリアミック酸の対数粘度〔η_ｉｎｈ　〕（Ｎ，Ｎ−ジメチルホルムアミド溶媒、温度３０℃、濃度０．５ｇ／ｄｌ）を、０．１〜４ｄｌ／ｇとすることが好ましく、０．３〜２ｄｌ／ｇとすることがより好ましい。
その他、上記製造条件を適宜調節することにより、得られるポリアミック酸において、イミド化率が５０％を超えない範囲内で、部分的にイミド化されていてもよい。
本発明のポリイミドは、上述したポリアミック酸を、脱水閉環してイミド化することにより製造することができる。このイミド化に際しては、以下に示すような加熱イミド化法または化学イミド化法を採用することができる。
【００１２】
（１）加熱イミド化法
▲１▼ポリアミック酸溶液をガラス、金属等の表面平滑な基材上に流延して加熱する方法、あるいは
▲２▼ポリアミック酸溶液をそのまま加熱する方法
等が適用される。
【００１３】
▲１▼の加熱イミド化法では、ポリアミック酸溶液を基板上に流延して形成された薄膜を、常圧下または減圧下で加熱することにより、フィルム状のポリイミドを得ることができる。
この場合の加熱温度は、通常、１００〜４５０℃の範囲内の値であり、好ましくは１５０〜４００℃の範囲内の値であり、反応中徐々に温度を上げることが好ましい。
【００１４】
また、▲２▼の加熱イミド化法では、ポリアミック酸溶液を加熱することにより、ポリイミドが粉末ないし溶液として得られる。この場合の加熱温度は、通常、８０〜３００℃の範囲内の値であり、好ましくは１００〜２５０℃の範囲内の値である。
また、▲２▼の加熱イミド化法に際しては、副生する水の除去を容易とするため、水と共沸し、特に反応系外で水と容易に分離しうる成分、例えば、ベンゼン、トルエン、キシレン等の芳香族炭化水素系溶媒を脱水剤として存在させることも好ましい。
また、▲２▼の加熱イミド化法に際しては、脱水閉環を促進するため、第三級アミン、例えば、トリメチルアミン、トリエチルアミン、トリプロピルアミン、トリブチルアミン等の脂肪族第三級アミン類；Ｎ，Ｎ−ジメチルアニリン、Ｎ，Ｎ−ジエチルアニリン等の芳香族第三級アミン類；ピリジン、キノリン、イソキノリン等の複素環式第三級アミン類等の触媒を添加することが好ましい。そして、かかる触媒の添加量を、ポリアミック酸１００重量部当たり、例えば１０〜４００重量部の範囲内の値とすることが好ましい。
さらに、▲２▼の加熱イミド化法に際して、クレゾール、クロロフェノール等のフェノール系溶媒中で加熱することも好ましい。このようにポリアミック酸を反応させることにより、一段階でポリイミドとすることができる。
また、▲１▼および▲２▼の加熱イミド化法を実施する際に、均一に反応を生じさせるために、有機溶媒を使用することが好ましい。例えば、ポリアミック酸の製造に使用される有機溶媒と同一の有機溶媒を使用することが好ましい。
その他、加熱イミド化法により得られたポリイミドが粉末の場合には、ろ過、噴霧乾燥、水蒸気蒸留等の適宜の方法により、ポリイミド粉末を有機溶媒から分離回収することができる。なお、この点は、化学イミド化法により得られたポリイミドの場合も同様である。
（２）化学イミド化法
次に、ポリイミドを作成するための化学イミド化法について説明する。この化学イミド化法として、例えば、
▲３▼ポリアミック酸を脱水環化させる閉環剤を用い、溶液状態でイミド化する方法を採用することができる。
【００１５】
この▲３▼の化学イミド化法によれば、ポリイミドが粉末あるいは溶液として得られる点に特徴がある。また、この化学イミド化法において、溶媒を使用することが好ましく、例えば、ポリアミック酸の製造に使用されるものと同様の有機溶媒を挙げることができる。
【００１６】
また、▲３▼の化学イミド化法に使用される閉環剤としては、例えば、無水酢酸、無水プロピオン酸、無水酪酸の如き酸無水物を挙げることができる。これらの閉環剤は、単独で使用することができるし、あるいは２種以上を混合して使用することもできる。
また、閉環剤の使用量を、前記一般式（２）で表される繰返し単位１モル当たり、通常、２〜１００モルの範囲内の値とするのが好ましく、２〜５０モルの範囲内の値とすることがより好ましい。
また、▲３▼の化学イミド化法における反応温度についても、特に制限されるものではないが、通常、０〜２００℃範囲内の値とするのが好ましい。
また、▲３▼の化学イミド化法において、加熱イミド化法の場合と同様に第三級アミンを触媒として使用することも好ましい。
【００１７】
本発明のポリイミドは、上述した層間絶縁膜以外の用途、例えば、ＬＳＩにおけるパッシベーション膜（ストレスバッファー膜）、α線遮断膜、フレキソ印刷版のカバーレイフィルム、フレキソ印刷版のオーバーコート等として使用することもできる。
また、ダイボンディング用接着剤、リード−オンチップ（ＬＯＣ）用接着テープ、リードフレーム固定用テープ、多層リードフレーム用接着フィルム等を挙げることもできる。
【００１８】
ポリイミドからなる層間絶縁膜を形成する際には、その前駆体であるポリアミック酸のワニスやペースト、あるいはポリイミドからなるフィルムやポリイミドワニス等を使用することができる。
ここで、層間絶縁膜の形成法は特に制限されるものではないが、例示すると下記のとおりである。
【００１９】
（イ）ポリアミック酸のワニスをＬＳＩの層間に流延し、ワニス中の過剰の有機溶媒を加熱下および減圧下あるいはいずれか一方の条件で除去して、該ポリアミック酸の薄膜を形成する。次いで、常圧下または加圧下で、一例として１００〜４５０℃の範囲内の温度で加熱し、ポリアミック酸を脱水閉環してイミド化し、層間絶縁膜とする方法。
（ロ）フィルム状のポリイミドをＬＳＩの層間に配置し、常圧下または加圧下で、例えば、１００〜４５０℃の範囲内の温度で加熱することにより熱圧着して、層間絶縁膜とする方法。
【００２０】
また、ポリイミドをフィルム状で取得する方法としては、例えば、
（ハ）予め離型処理した基板、例えば、ガラス、テフロン（登録商標）、ポリエステル等の基板上に、ポリアミック酸のワニスを流延し、次いで、徐々に加熱して溶媒を除去しつつ脱水閉環し、イミド化して、フィルム状とする方法。
（ニ）ポリイミドの粉末を、プレス成形、射出成形等の適宜の方法によりフィルム状に成形する方法。
（ホ）第１発明のポリアミック酸あるいは第２発明のポリイミドのワニスを基板上に流延したのち、加熱し、乾燥することによって、厚さ数十〜数百μｍのポリイミドのドライフィルムとする方法。
【００２１】
【実施例】
以下、実施例により本発明をさらに詳細に説明するが、本発明はこれらの実施例に限定されるものではない。
【００２２】
［合成例１］
（１）１，３−ジブロモアダマンタンの合成
窒素導入管、コールドトラップを備え付けた三口フラスコ（１００ｍＬ）に窒素気流下、臭素４８．８ｍＬ　（０．９５２　ｍｏｌ）、アルミホイル９．７１ｍｇ　（０．３６　ｍｍｏｌ）を入れ赤色の光が消えるまで室温で撹拌し、１０分後三臭化ホウ素９．４３　ｍＬ　（９９．８　ｍｍｏｌ）を加え、室温で１０分撹拌した。その後１−ブロモアダマンタン６．８４ｇ　（３１．８　ｍｍｏｌ）を加え、８５℃で２時間撹拌した。撹拌終了後、氷水で冷却し、反応溶液を氷水に投入し、亜硫酸水素ナトリウムを臭素の色が消えるまで加えた後、クロロホルムで抽出した。得られた粗生成物をメタノールにより再結晶した。収量は６．９０　ｇ（収率７４％）、融点１０８−１０９℃　（ｌｉｔ．　１１０℃）であった。構造確認は^１Ｈ−ＮＭＲ、^１３Ｃ−ＮＭＲにより行った。
（２）１，３−ビス（４−ヒドロキシフェニル）アダマンタンの合成
１，３−ジブロモアダマンタン１．９０ｇ　（６．４６　ｍｍｏｌ）、フェノール１９．０ｇ　（２０２　ｍｍｏｌ）、塩化アルミニウム２．１５ｇ　（１６．１　ｍｍｏｌ）を三口フラスコに加え、８０℃で１６時間撹拌した。撹拌終了後、お湯（８０℃）で２回洗浄した。収量は１．９２ｇ　（収率９３％）、融点は１９８−２００℃　（ｌｉｔ．　１９９−２０１℃）であった。構造確認は元素分析、^１Ｈ−ＮＭＲ、^１３Ｃ−ＮＭＲにより行った。
（３）１，３−ビス［４−（４−ニトロフェノキシ）フェニル］アダマンタンの合成
１，３−ビス（４−ヒドロキシフェニル）アダマンタン０．９４０ｇ　（２．９３　ｍｍｏｌ）、４−クロロニトロベンゼン１．０１ｇ　（６．４２　ｍｍｏｌ）、炭酸カリウム０．８９０ｇ　（６．４４　ｍｍｏｌ）をジメチルホルムアミド　（２８．２　ｍＬ）に加え、１６０℃で１２時間撹拌した。撹拌終了後、室温まで冷却し、蒸留水に投じた。ろ別後減圧乾燥した。収量は１．６２ｇ　（収率９８％）、融点は２１６−２１８℃　（ｌｉｔ．　２１６−２１８℃）であった。構造確認は元素分析、^１Ｈ−ＮＭＲにより行った。
（４）１，３−ビス［４−（４−アミノフェノキシ）フェニル］アダマンタンの合成
１，３−ビス［４−（４−ニトロフェノキシ）フェニル］アダマンタン８．２４ｇ　（１４．７　ｍｍｏｌ）をジメチルホルムアミド／エタノール混合溶媒　（２７５　ｍＬ）に加え、ここにヒドラジン一水和物　（８２．４　ｍＬ）、Ｐｄ−Ｃ（１０　％）　０．１６５ｇを加え、８０℃で１６時間撹拌した。撹拌終了後、セライトでろ過し、反応溶液を１００ｍＬ程度まで濃縮した。その後、蒸留水に投じて１時間撹拌し、ろ別乾燥した。さらにこの生成物をエタノール中で１時間還流を行い、ろ別後減圧乾燥した。収率６２％、融点１８２−１８４℃　（ｌｉｔ．　１９１−１９３℃）。構造確認は^１Ｈ−ＮＭＲにより行った（図１）。
（５）３，３’−ビス［４−（３（ｏｒ　４）−アミノフェノキシ）フェニル］−１，１’−ビアダマンタンの合成
（５−１）１，１’−ビアダマンタンの合成
窒素気流下、１−ブロモアダマンタン２５．１ｇ　（１１７　ｍｍｏｌ）をｍ−キシレン（５０　ｍＬ）に溶解させ、還流させた。還流開始後、ナトリウム２．７１ｇ　（１１８　ｍｍｏｌ）を少しずつ４時間かけて加え、その後１２時間還流した。還流後、溶液を熱時ろ過し、析出した固体をろ別乾燥後、トルエンにより再結晶を行った。収量６．７８　ｇ　（収率　４３％）、融点２８８−２９０℃　（ｌｉｔ．　２８８−２９０℃）。構造確認は^１Ｈ−ＮＭＲ、^１３Ｃ−ＮＭＲにより行った。
（５−２）３，３’−ジブロモ−１，１’−ビアダマンタンの合成
窒素導入管、コールドトラップを備え付けた三口フラスコ（１００ｍＬ）に窒素気流下、１，１’−ビアダマンタン５．２９ｇ　（１９．６　ｍｍｏｌ）を入れ、ここに臭素２８．１ｍＬ　（０．５４９　ｍｏｌ）を加え、室温で１５分撹拌した。その後還流を２時間行った。反応終了後、反応物を氷水で冷却し、クロロホルムと氷水を加えた。亜硫酸水素ナトリウムを臭素の色が消えるまで加え、その後クロロホルムで抽出した。さらにクロロホルム溶液を重曹水で洗浄し、クロロホルム溶液に溶けている臭化水素を中和した後、硫酸マグネシウムを加えて乾燥させた。ろ別後、クロロホルム溶液を濃縮し、得られた固体を１，４−ジオキサンにより再結晶した。収量７．０３ｇ　（収率８４％）、融点２３７−２３９℃　（ｌｉｔ．　２３６−２３７℃）。構造確認は^１Ｈ−ＮＭＲ、^１３Ｃ−ＮＭＲにより行った。
（５−３）３，３’−ジ−（４−ヒドロキシフェニル）−１，１’−ビアダマンタンの合成
３，３’−ジブロモ−１，１’−ビアダマンタン４．３１ｇ　（１０．１　ｍｍｏｌ）、フェノール３７．９ｇ　（４０２　ｍｍｏｌ）、塩化アルミニウム３．３５ｇ　（２５．２　ｍｍｏｌ）を三口フラスコに加え、８０℃で１６時間撹拌した。撹拌終了後、水（８０℃）で２回洗浄しろ別後減圧乾燥した。得られた固体を酢酸エチルにより再結晶した。収量４．００ｇ　（収率８７％）、融点３４３−３４４℃。構造確認は^１Ｈ−ＮＭＲにより行った。
（５−４）３，３’−ビス［４−（３（ｏｒ　４）−ニトロフェノキシ）フェニル］−１，１’−ビアダマンタンの合成
３，３’−ジ−（４−ヒドロキシフェニル）−１，１’−ビアダマンタン４．０７ｇ　（８．９５　ｍｍｏｌ）、１，３−ジニトロベンゼン（ｏｒ　４−クロロニトロベンゼン）３．２９ｇ　（１９．６　ｍｍｏｌ）、炭酸カリウム２．７１ｇ　（１９．６　ｍｍｏｌ）をＤＭＦ　（１２２　ｍＬ）に加え、１６０℃で１２時間撹拌した。撹拌終了後、室温まで冷却し、蒸留水に投じた。ろ別後減圧乾燥した。得られた固体をＤＭＡｃにより再結晶した。収量５．１８ｇ　（収率８３％）。構造確認は、^１Ｈ−ＮＭＲにより行った。
（５−５）３，３’−ビス［４−（３−アミノフェノキシ）フェニル］−１，１’−ビアダマンタンの合成
３，３’−ビス［４−（３−ニトロフェノキシ）フェニル］−１，１’−ビアダマンタン５．１５ｇ　（７．３９ｍｍｏｌ）をＤＭＡｃ：エタノール＝３：１混合溶媒　（１７２　ｍＬ）に加え、ここにヒドラジン一水和物　（３０　ｍＬ）、Ｐｄ−Ｃ（１０　％）　０．１０３ｇを加え、８０℃で１６時間撹拌した。撹拌終了後、セライトでろ過し、反応溶液を１００ｍＬ程度まで濃縮した。その後、蒸留水に投じて１時間撹拌し、ろ別乾燥した。得られた固体をＤＭＡｃにより再結晶した。収量３．２８ｇ　（収率７０％）。構造確認は^１Ｈ−ＮＭＲにより行った。
【００２３】
［実施例１］
１，３−ビス［４−（４−アミノフェノキシ）フェニル］アダマンタン０．５０６ｇ　（１．０１　ｍｍｏｌ）をＮ−メチルピロリドン（２．８１　ｇ）に溶解させ、ここに１，２，３，４−シクロブタンテトラカルボン酸二無水物（ＣＢＤＡ）　０．１９７ｇ　（１．０１　ｍｍｏｌ）を加え、窒素雰囲気下、室温で７時間、８０℃で２３時間反応させた。反応終了後、重合溶液をＮＭＰで希釈し、水：メタノール混合溶液（１００　ｍＬ）に投じ、室温で１時間撹拌した。撹拌終了後、ろ別し、減圧乾燥し、ポリアミック酸を得た。収率は８９％であった。構造確認はＩＲスペクトルにより行った。ポリアミック酸を、窒素気流下７０℃で２時間、１６０℃で１時間、２５０℃で３０分、３００℃で１時間熱処理することによりポリイミドを得た。
ＩＲスペクトルはＨｏｒｉｂａ　ＦＴ−７２０により測定した。^１Ｈ　ＮＭＲ、^１３Ｃ−ＮＭＲはＢｒｕｋｅｒ　ＤＰＸ３００　（３００ＭＨｚ）により測定した。熱分析は、ＳｅｉｋｏＴＧ／ＤＴＡ　６３００により測定した。屈折率はＰＣ−２０００プリズムカプラーにより測定した。
ポリマーの構造確認はＩＲスペクトルにより行った。ここで得られたポリアミド酸はＮＭＰ、ＤＭＡｃ、ＤＭＦ、ＤＭＳＯ等の溶媒に可溶であった。また、窒素気流下でイミド化を行い、構造確認はＩＲスペクトルにより行った。
【００２４】
［実施例２］
１，２，３，４−シクロブタンテトラカルボン酸二無水物（ＣＢＤＡ）　０．１９７ｇ　（１．０１　ｍｍｏｌ）の代りにビシクロ［２．２．２］オクト−７−エン−２，３；５，６−テトラカルボン酸二無水物（ＢＣＤＡ）１．０１ｍｍｏｌを使用した以外は実施例１と同様にして重合を行い、ポリアミック酸およびポリイミドを得た。
［実施例３］
１，２，３，４−シクロブタンテトラカルボン酸二無水物（ＣＢＤＡ）　０．１９７ｇ　（１．０１　ｍｍｏｌ）の代りにビシクロ［２．２．１］ヘプタン−２−メタンカルボン酸二無水物（ＮＤＡ）１．０１ｍｍｏｌを使用した以外は実施例１と同様にして重合を行い、ポリアミック酸およびポリイミドを得た。
【００２５】
評価結果
実施例１で得られたポリイミドのガラス転移点（チッ素雰囲気下、昇温温度１０℃／分、ＤＳＣ測定）は検出されず、分解開始温度は３８７℃、５％重量損失温度は４６４℃、１００％重量損失温度は４８２℃であった。
また、実施例１〜３で得られたポリイミドの屈折率から算出した比誘電率は２．７８（実施例１）、２．７４（実施例２）および２．６９（実施例３）であった。
【００２６】
［実施例４］
３，３’−ビス［４−（３−アミノフェノキシ）フェニル］−１，１’−ビアダマンタン０．６４６ｇ　（１．０１　ｍｍｏｌ）をＮＭＰ（３．３８　ｇ）に溶解させ、ここに１，２，３，４−シクロブタンテトラカルボン酸二無水物（ＣＢＤＡ）　０．１９９ｇ　（１．０１　ｍｍｏｌ）を加え、窒素雰囲気下、室温で７時間、８０℃で２３時間反応させた。反応終了後、重合溶液をＮＭＰで希釈し、水：メタノール混合溶液（１００　ｍＬ）に投じ、室温で１時間撹拌した。撹拌終了後、ろ別し、減圧乾燥した。収率８０％。構造確認はＩＲスペクトルにより行った。熱イミド化は、窒素気流下７０℃で２時間、１６０℃で１時間、２５０℃で３０分、３００℃で１時間熱処理することにより行った。
熱分析は、ＳｅｉｋｏＴＧ／ＤＴＡ　６３００により測定した。屈折率はＰＣ−２０００プリズムカプラーにより測定した。
得られたポリイミドのガラス転移温度は２８８℃、５％重量減少温度が４７２℃、１０％重量減少温度が４８９℃と比較的高い耐熱性を示し、比誘電率を屈折率から換算したところ２．７であった。
【００２７】
【発明の効果】
本発明のポリイミドは比誘電率が低く、耐熱性にも優れるので半導体の層間絶縁膜などの電子材料として好適である。
【図面の簡単な説明】
【図１】１，３−ビス［４−（４−アミノフェノキシ）フェニル］アダマンタンの^１Ｈ−ＮＭＲスペクトル。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a polyimide, a polyamic acid, and an interlayer insulating film using the same. More specifically, the present invention relates to an LSI (large-scale integrated circuit) having excellent adhesion to various substrates, excellent heat resistance and low dielectric constant characteristics, and The present invention relates to a polyimide that is optimal as an interlayer insulating film in an integrated circuit, a polyamic acid as a precursor capable of forming the polyimide, and an interlayer insulating film made of the polyimide.
[0002]
[Prior art]
2. Description of the Related Art In recent years, LSIs (large-scale integrated circuits) have continued to be highly integrated, multifunctional, and high-performance due to advances in fine processing technology. As a result, the circuit resistance and the capacitance between the wirings (hereinafter referred to as "parasitic resistance" and "parasitic capacitance", respectively) increase, and not only the power consumption increases, but also the delay time for the input signal increases. ing. Therefore, an increase in the parasitic resistance and the parasitic capacitance is a major factor in lowering the signal speed in the LSI, and the solution thereof is a major problem.
[0003]
Accordingly, the interlayer insulating film in the LSI is made of a low dielectric organic material, and the relative dielectric constant of the interlayer insulating film is reduced, thereby improving the high frequency characteristics. As a result, the parasitic resistance and the parasitic capacitance are reduced, and the signal in the LSI is reduced. Speeding up. Specifically, a fluororesin represented by polytetrafluoroethylene (PTFE) is used as a low dielectric organic material for an interlayer insulating film in an LSI.
However, although such a fluororesin has a relatively low value of the relative dielectric constant, it has a problem that heat resistance and mechanical strength are insufficient as an organic material for an interlayer insulating film. In addition, fluororesin generally has poor adhesion to a base material, and when used for an interlayer insulating film of an LSI, the interlayer insulating film is peeled off due to low adhesive strength to a substrate or wiring, resulting in a long-term LSI chip. There was also the problem of poor reliability.
[0004]
Also, use of polyimide as an organic material for an interlayer insulating film of an LSI has been proposed. However, the value of the relative dielectric constant of a general polyimide is in the range of 3.0 to 3.5, and it is still insufficient as an organic material for an interlayer insulating film of an LSI aiming at a higher signal speed. Polyimide also has poor adhesion to substrates, and in fields where high reliability under high temperature and high humidity is required, such as semiconductor devices and circuit boards, the adhesive strength between polyimide and the substrate or wiring is low. The problem was that long-term reliability was poor due to the low temperature.
[0005]
Therefore, as a method of improving the adhesiveness, it has been proposed to introduce a siloxane bond into the main chain of polyimide (JP-A-5-112760, JP-A-9-255780, etc.).
However, although these polyimides are excellent in adhesiveness, the value of the relative dielectric constant exceeds 3, and there is a problem that they cannot be used for interlayer insulating films.
[0006]
[Problems to be solved by the invention]
The present invention has completed the present invention by introducing an adamantane skeleton into a polyimide molecule.
That is, the present invention has a low relative dielectric constant, and has excellent heat resistance, the most suitable polyimide as an interlayer insulating film in LSI, and a polyamic acid as a precursor capable of forming the polyimide, and the polyimide An object of the present invention is to provide a polyimide varnish dissolved in a solvent.
[0007]
[Means for Solving the Invention]
[0008]
The present invention provides a polyimide comprising a repeating unit represented by the following general formula (1), preferably a repeating unit represented by the following general formula (2), and a polyimide represented by the following general formula (3) A polyamic acid comprising a repeating unit, preferably a repeating unit represented by the following general formula (4), and an interlayer insulating film comprising the polyimide.
General formula (1)
Embedded image

(In the formula, X represents a tetravalent cyclic aliphatic group, and Y represents a divalent aromatic group having an adamantane structure.)
General formula (2)
Embedded image

(Wherein, X represents a tetravalent cyclic aliphatic group)
General formula (3)
Embedded image

(In the formula, X represents a tetravalent cyclic aliphatic group, and Y represents a divalent aromatic group having an adamantane structure.)
General formula (4)
Embedded image

(Wherein, X represents a tetravalent cyclic aliphatic group)
[0009]
The polyamic acid of the present invention can be produced by polycondensing an aromatic diamine compound having an adamantane structure with a cycloaliphatic tetracarboxylic dianhydride in an organic solvent.
Examples of the aromatic diamine compound having an adamantane structure include 1,3-bis (4-aminophenyl) adamantane, 1,3-bis [4- (4-aminophenoxy) phenyl] adamantane (general formula (5)), , 6-Bis (4-aminophenyl) diamantane, 1,6-bis [4- (4-aminophenoxy) phenyl] diamantane, 4,9-bis (4-aminophenyl) diamantane, 4,9-bis [4 -(4-aminophenoxy) phenyl] diamantane, 3,3'-bis [4- (3-aminophenoxy) phenyl] -1,1'-biadamantane, 3,3'-bis [4- (4-amino Phenoxy) phenyl] -1,1′-biadamantane and the like.
General formula (5)
Embedded image

[0010]
Examples of the cycloaliphatic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6- Tetracarboxylic dianhydride, bicyclo [2.2.1] heptane-2-methanecarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxy Acetic acid dianhydride, bicyclo [2.2.1] heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.1] heptane-2,3,5-tricarboxyacetic acid dianhydride Anhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3, 5,6-tetracarboxylic dianhydride, 5- (2,5-dioxy (Tetrahydrofurfuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 3-oxabicyclo [3.2.1] octane-2,4-dione-6-spiro-3 ′-(tetrahydrofuran -2 ', 5'-dione), decahydro-1,4,5,8-dimethanonaphthalene-2,3,6,7-tetracarboxylic dianhydride.
The aromatic diamine compound having an adamantane structure and the cycloaliphatic tetracarboxylic dianhydride are reacted with each other in approximately equimolar amounts, and the reaction temperature is about 50 to 90 ° C.
[0011]
The logarithmic viscosity [η _inh ] (N, N-dimethylformamide solvent, temperature 30 ° C., concentration 0.5 g / dl) of the polyamic acid is adjusted to 0.1 to 4 dl / g by appropriately adjusting the above production conditions. And more preferably 0.3 to 2 dl / g.
In addition, by appropriately adjusting the above production conditions, the resulting polyamic acid may be partially imidized within an imidation ratio not exceeding 50%.
The polyimide of the present invention can be produced by dehydrating and cyclizing the above-described polyamic acid to imidize it. In this imidization, a heat imidation method or a chemical imidization method as described below can be employed.
[0012]
(1) Heat imidization method (1) A method in which a polyamic acid solution is cast on a substrate having a smooth surface such as glass or metal and heated, or a method (2) in which a polyamic acid solution is directly heated is applied. You.
[0013]
In the heat imidization method (1), a film-like polyimide can be obtained by heating a thin film formed by casting a polyamic acid solution on a substrate under normal pressure or reduced pressure.
The heating temperature in this case is usually a value in the range of 100 to 450 ° C, preferably a value in the range of 150 to 400 ° C, and it is preferable to gradually increase the temperature during the reaction.
[0014]
In the thermal imidization method (2), the polyimide is obtained as a powder or a solution by heating the polyamic acid solution. The heating temperature in this case is usually a value in the range of 80 to 300 ° C, preferably a value in the range of 100 to 250 ° C.
In the thermal imidization method (2), components that azeotrope with water and are easily separated from water especially outside the reaction system, such as benzene and toluene, in order to facilitate removal of by-produced water. It is also preferred that an aromatic hydrocarbon solvent such as xylene or the like be present as a dehydrating agent.
In the thermal imidization method (2), tertiary amines, for example, aliphatic tertiary amines such as trimethylamine, triethylamine, tripropylamine and tributylamine; N, N It is preferable to add a catalyst such as aromatic tertiary amines such as -dimethylaniline and N, N-diethylaniline; and heterocyclic tertiary amines such as pyridine, quinoline and isoquinoline. It is preferable that the amount of such a catalyst be in the range of, for example, 10 to 400 parts by weight per 100 parts by weight of the polyamic acid.
Further, in the thermal imidization method (2), it is also preferable to heat in a phenolic solvent such as cresol or chlorophenol. By reacting the polyamic acid in this way, a polyimide can be obtained in one step.
Further, when the heat imidization method (1) or (2) is carried out, it is preferable to use an organic solvent in order to cause a uniform reaction. For example, it is preferable to use the same organic solvent as the organic solvent used for producing the polyamic acid.
In addition, when the polyimide obtained by the heat imidization method is a powder, the polyimide powder can be separated and recovered from the organic solvent by an appropriate method such as filtration, spray drying, and steam distillation. This is the same in the case of polyimide obtained by the chemical imidization method.
(2) Chemical imidization method Next, a chemical imidization method for producing polyimide will be described. As this chemical imidation method, for example,
{Circle around (3)} A method of imidizing in a solution state using a ring-closing agent for dehydrating and cyclizing a polyamic acid can be adopted.
[0015]
According to the chemical imidization method (3), the polyimide is obtained as a powder or a solution. Further, in this chemical imidization method, it is preferable to use a solvent, and examples thereof include the same organic solvents as those used in the production of polyamic acid.
[0016]
Examples of the ring closing agent used in the chemical imidization method (3) include acid anhydrides such as acetic anhydride, propionic anhydride and butyric anhydride. These ring closing agents can be used alone or in combination of two or more.
In addition, the amount of the ring-closing agent to be used is usually preferably a value within the range of 2 to 100 mol, and preferably within the range of 2 to 50 mol, per 1 mol of the repeating unit represented by the general formula (2). It is more preferable to set the value.
The reaction temperature in the chemical imidization method (3) is not particularly limited, but is usually preferably in the range of 0 to 200 ° C.
In the chemical imidation method (3), it is also preferable to use a tertiary amine as a catalyst, as in the case of the thermal imidization method.
[0017]
The polyimide of the present invention is used for applications other than the above-described interlayer insulating film, for example, as a passivation film (stress buffer film) in an LSI, an α-ray blocking film, a coverlay film for a flexographic printing plate, an overcoat for a flexographic printing plate, and the like. You can also.
In addition, an adhesive for die bonding, an adhesive tape for lead-on-chip (LOC), a tape for fixing a lead frame, an adhesive film for a multilayer lead frame, and the like can also be given.
[0018]
When forming an interlayer insulating film made of polyimide, a varnish or paste of a polyamic acid as a precursor thereof, a film made of polyimide, a polyimide varnish, or the like can be used.
Here, the method of forming the interlayer insulating film is not particularly limited, but is exemplified as follows.
[0019]
(A) A varnish of a polyamic acid is cast between layers of an LSI, and an excess organic solvent in the varnish is removed under heating and / or reduced pressure to form a thin film of the polyamic acid. Next, a method of heating at a temperature in the range of 100 to 450 [deg.] C. under normal pressure or pressure, for example, and dehydrating and ring-closing the polyamic acid to form an imidation to form an interlayer insulating film.
(B) A method of arranging a film-like polyimide between layers of an LSI, and thermocompression bonding under normal pressure or under pressure, for example, by heating at a temperature in the range of 100 to 450 ° C. to form an interlayer insulating film.
[0020]
Further, as a method of obtaining polyimide in a film form, for example,
(C) A varnish of polyamic acid is cast on a substrate that has been subjected to a release treatment in advance, for example, a substrate of glass, Teflon (registered trademark), polyester, or the like, and then dehydration and ring closure is performed while gradually removing the solvent by heating. And imidization to form a film.
(D) A method of molding a polyimide powder into a film by an appropriate method such as press molding or injection molding.
(E) A method in which a varnish of the polyamic acid of the first invention or the varnish of the polyimide of the second invention is cast on a substrate, and then heated and dried to obtain a dry film of polyimide having a thickness of several tens to several hundreds of μm. .
[0021]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
[0022]
[Synthesis Example 1]
(1) Synthesis of 1,3-dibromoadamantane In a three-necked flask (100 mL) equipped with a nitrogen inlet tube and a cold trap, under a nitrogen stream, 48.8 mL (0.952 mol) of bromine, 9.71 mg of aluminum foil (0.36 mol) mmol) and stirred at room temperature until the red light disappeared. After 10 minutes, 9.43 mL (99.8 mmol) of boron tribromide was added, and the mixture was stirred at room temperature for 10 minutes. Thereafter, 6.84 g (31.8 mmol) of 1-bromoadamantane was added, and the mixture was stirred at 85 ° C for 2 hours. After completion of the stirring, the mixture was cooled with ice water, the reaction solution was poured into ice water, sodium bisulfite was added until the color of bromine disappeared, and the mixture was extracted with chloroform. The obtained crude product was recrystallized from methanol. The yield was 6.90 g (74% yield), melting point 108-109 ° C (lit. 110 ° C). The structure was confirmed by ¹ H-NMR and ¹³ C-NMR.
(2) Synthesis of 1,3-bis (4-hydroxyphenyl) adamantane 1.90 g (6.46 mmol) of 1,3-dibromoadamantane, 19.0 g (202 mmol) of phenol, 2.15 g of aluminum chloride (16. 1 mmol) was added to a three-necked flask and stirred at 80 ° C. for 16 hours. After the completion of stirring, the resultant was washed twice with hot water (80 ° C). The yield was 1.92 g (93% yield) and the melting point was 198-200 ° C (lit. 199-201 ° C). The structure was confirmed by elemental analysis, ¹ H-NMR, and ¹³ C-NMR.
(3) Synthesis of 1,3-bis [4- (4-nitrophenoxy) phenyl] adamantane 0.940 g (2.93 mmol) of 1,3-bis (4-hydroxyphenyl) adamantane, 4-chloronitrobenzene 01 g (6.42 mmol) and 0.890 g (6.44 mmol) of potassium carbonate were added to dimethylformamide (28.2 mL), and the mixture was stirred at 160 ° C. for 12 hours. After completion of the stirring, the mixture was cooled to room temperature and poured into distilled water. After filtration, the filtrate was dried under reduced pressure. The yield was 1.62 g (98% yield) and the melting point was 216-218 ° C (lit. 216-218 ° C). The structure was confirmed by elemental analysis and ¹ H-NMR.
(4) Synthesis of 1,3-bis [4- (4-aminophenoxy) phenyl] adamantane 8.24 g (14.7 mmol) of 1,3-bis [4- (4-nitrophenoxy) phenyl] adamantane was dissolved in dimethyl To a mixed solvent of formamide / ethanol (275 mL), hydrazine monohydrate (82.4 mL) and 0.165 g of Pd-C (10%) were added, and the mixture was stirred at 80 ° C for 16 hours. After completion of the stirring, the mixture was filtered through Celite, and the reaction solution was concentrated to about 100 mL. Thereafter, the mixture was poured into distilled water, stirred for 1 hour, and filtered and dried. The product was refluxed for 1 hour in ethanol, filtered and dried under reduced pressure. Yield 62%, mp 182-184 ° C (lit. 191-193 ° C). The structure was confirmed by ¹ H-NMR (FIG. 1).
(5) Synthesis of 3,3'-bis [4- (3 (or 4) -aminophenoxy) phenyl] -1,1'-biadamantane (5-1) Synthesis of 1,1'-biadamantane Nitrogen gas flow Below, 25.1 g (117 mmol) of 1-bromoadamantane was dissolved in m-xylene (50 mL) and refluxed. After the start of reflux, 2.71 g (118 mmol) of sodium was added little by little over 4 hours, and then refluxed for 12 hours. After the reflux, the solution was filtered while hot, and the precipitated solid was separated by filtration, dried, and recrystallized with toluene. Yield 6.78 g (43% yield), mp 288-290 ° C (lit. 288-290 ° C). The structure was confirmed by ¹ H-NMR and ¹³ C-NMR.
(5-2) Synthesis of 3,3′-dibromo-1,1′-biadamantane 5.29 g of 1,1′-biadamantane in a three-necked flask (100 mL) equipped with a nitrogen inlet tube and a cold trap under a nitrogen stream. (19.6 mmol), 28.1 mL (0.549 mol) of bromine was added thereto, and the mixture was stirred at room temperature for 15 minutes. Thereafter, reflux was performed for 2 hours. After completion of the reaction, the reaction product was cooled with ice water, and chloroform and ice water were added. Sodium bisulfite was added until the bromine color disappeared, and then extracted with chloroform. Further, the chloroform solution was washed with an aqueous solution of sodium bicarbonate to neutralize hydrogen bromide dissolved in the chloroform solution, and then dried by adding magnesium sulfate. After filtration, the chloroform solution was concentrated, and the obtained solid was recrystallized with 1,4-dioxane. Yield 7.03 g (84% yield), mp 237-239 ° C (lit. 236-237 ° C). The structure was confirmed by ¹ H-NMR and ¹³ C-NMR.
(5-3) Synthesis of 3,3'-di- (4-hydroxyphenyl) -1,1'-biadamantane 4.31 g of 3,3'-dibromo-1,1'-biadamantane (10.1 mmol ), 37.9 g (402 mmol) of phenol and 3.35 g (25.2 mmol) of aluminum chloride were added to a three-necked flask and stirred at 80 ° C. for 16 hours. After completion of the stirring, the mixture was washed twice with water (80 ° C.), separated by filtration, and dried under reduced pressure. The obtained solid was recrystallized from ethyl acetate. Yield 4.00 g (87% yield), mp 343-344 ° C. The structure was confirmed by ¹ H-NMR.
(5-4) Synthesis of 3,3′-bis [4- (3 (or 4) -nitrophenoxy) phenyl] -1,1′-biadamantane 3,3′-di- (4-hydroxyphenyl)- 4.07 g (8.95 mmol) of 1,1′-biadamantane, 3.29 g (19.6 mmol) of 1,3-dinitrobenzene (or 4-chloronitrobenzene), 2.71 g (19.6 mmol) of potassium carbonate ) Was added to DMF (122 mL) and stirred at 160 ° C for 12 hours. After completion of the stirring, the mixture was cooled to room temperature and poured into distilled water. After filtration, the filtrate was dried under reduced pressure. The obtained solid was recrystallized by DMAc. 5.18 g (83% yield). The structure was confirmed by ¹ H-NMR.
(5-5) Synthesis of 3,3'-bis [4- (3-aminophenoxy) phenyl] -1,1'-biadamantane 3,3'-bis [4- (3-nitrophenoxy) phenyl]- 5.15 g (7.39 mmol) of 1,1′-biadamantane was added to a mixed solvent of DMAc: ethanol = 3: 1 (172 mL), and hydrazine monohydrate (30 mL) and Pd—C (10%) were added thereto. ) And stirred at 80 ° C for 16 hours. After completion of the stirring, the mixture was filtered through Celite, and the reaction solution was concentrated to about 100 mL. Thereafter, the mixture was poured into distilled water, stirred for 1 hour, and filtered and dried. The obtained solid was recrystallized by DMAc. 3.28 g (70% yield). The structure was confirmed by ¹ H-NMR.
[0023]
[Example 1]
0.506 g (1.01 mmol) of 1,3-bis [4- (4-aminophenoxy) phenyl] adamantane is dissolved in N-methylpyrrolidone (2.81 g), and 1,2,3,4 0.197 g (1.01 mmol) of -cyclobutanetetracarboxylic dianhydride (CBDA) was added, and the mixture was reacted under a nitrogen atmosphere at room temperature for 7 hours and at 80 ° C for 23 hours. After completion of the reaction, the polymerization solution was diluted with NMP, poured into a water: methanol mixed solution (100 mL), and stirred at room temperature for 1 hour. After completion of the stirring, the mixture was filtered and dried under reduced pressure to obtain a polyamic acid. The yield was 89%. The structure was confirmed by IR spectrum. The polyamic acid was heat-treated at 70 ° C. for 2 hours, 160 ° C. for 1 hour, 250 ° C. for 30 minutes, and 300 ° C. for 1 hour under a nitrogen stream to obtain a polyimide.
The IR spectrum was measured by Horiba FT-720. ¹ H NMR and ¹³ C-NMR were measured with a Bruker DPX300 (300 MHz). Thermal analysis was measured by SeikoTG / DTA 6300. The refractive index was measured using a PC-2000 prism coupler.
The structure of the polymer was confirmed by IR spectrum. The polyamic acid obtained here was soluble in solvents such as NMP, DMAc, DMF and DMSO. In addition, imidation was carried out under a nitrogen stream, and the structure was confirmed by IR spectrum.
[0024]
[Example 2]
Instead of 0.197 g (1.01 mmol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), bicyclo [2.2.2] oct-7-ene-2,3; 5 Polymerization was carried out in the same manner as in Example 1 except that 1.01 mmol of 6-tetracarboxylic dianhydride (BCDA) was used to obtain a polyamic acid and a polyimide.
[Example 3]
Instead of 0.197 g (1.01 mmol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), bicyclo [2.2.1] heptane-2-methanecarboxylic dianhydride (NDA) ) Polymerization was carried out in the same manner as in Example 1 except that 1.01 mmol was used to obtain a polyamic acid and a polyimide.
[0025]
Evaluation Results No glass transition point (temperature rising temperature: 10 ° C./minute, DSC measurement) of the polyimide obtained in Example 1 was detected, the decomposition onset temperature was 387 ° C., and the 5% weight loss temperature was 464. ° C, 100% weight loss temperature was 482 ° C.
The relative dielectric constants calculated from the refractive indices of the polyimides obtained in Examples 1 to 3 were 2.78 (Example 1), 2.74 (Example 2) and 2.69 (Example 3). Was.
[0026]
[Example 4]
0.646 g (1.01 mmol) of 3,3′-bis [4- (3-aminophenoxy) phenyl] -1,1′-biadamantane was dissolved in NMP (3.38 g), and 1, 0.199 g (1.01 mmol) of 2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) was added, and the mixture was reacted under a nitrogen atmosphere at room temperature for 7 hours and at 80 ° C. for 23 hours. After completion of the reaction, the polymerization solution was diluted with NMP, poured into a water: methanol mixed solution (100 mL), and stirred at room temperature for 1 hour. After completion of the stirring, the mixture was filtered and dried under reduced pressure. Yield 80%. The structure was confirmed by IR spectrum. The thermal imidization was performed by heat treatment at 70 ° C. for 2 hours, 160 ° C. for 1 hour, 250 ° C. for 30 minutes, and 300 ° C. for 1 hour under a nitrogen stream.
Thermal analysis was measured by SeikoTG / DTA 6300. The refractive index was measured using a PC-2000 prism coupler.
The glass transition temperature of the obtained polyimide was 288 ° C., the 5% weight loss temperature was 472 ° C., and the 10% weight loss temperature was 489 ° C., indicating relatively high heat resistance. The relative dielectric constant was calculated from the refractive index. It was 7.
[0027]
【The invention's effect】
Since the polyimide of the present invention has a low relative dielectric constant and excellent heat resistance, it is suitable as an electronic material such as a semiconductor interlayer insulating film.
[Brief description of the drawings]
FIG. 1 is a ¹ H-NMR spectrum of 1,3-bis [4- (4-aminophenoxy) phenyl] adamantane.

Claims (5)

A polyimide comprising a repeating unit represented by the following general formula (1).
General formula (1)

(In the formula, X represents a tetravalent cyclic aliphatic group, and Y represents a divalent aromatic group having an adamantane structure.) The polyimide according to claim 1, comprising a repeating unit represented by the following general formula (2).
General formula (2)

(Wherein, X represents a tetravalent cyclic aliphatic group) A polyamic acid comprising a repeating unit represented by the following general formula (3).
General formula (3)

(In the formula, X represents a tetravalent cyclic aliphatic group, and Y represents a divalent aromatic group having an adamantane structure.) The polyamic acid according to claim 3, comprising a repeating unit represented by the following general formula (4).
General formula (4)

(Wherein, X represents a tetravalent cyclic aliphatic group) An interlayer insulating film comprising the polyimide according to claim 1.

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