JP3786051B2 - Polyimide, polyamic acid and interlayer insulation film - Google Patents

Description

（式中、Ｘは４価の環状脂肪族基を示す）
一般式（２）
【化６】

（式中、Ｘは４価の環状脂肪族基を示す）
【０００９】
本発明のポリアミック酸は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））または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。
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。
１，３−ビス［４−（４−アミノフェノキシ）フェニル］アダマンタンまたは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
（Ａ）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
（Ｂ）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】
（Ａ）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、（Ｂ）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、（Ｂ）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、（Ｂ）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、（Ｂ）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、（Ａ）および（Ｂ）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、
（Ｃ）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（Ｃ）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、（Ｃ）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、（Ｃ）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、（Ｃ）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 （７．３９ ｍｍｏｌ）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]
BACKGROUND OF THE INVENTION
The present invention relates to polyimide, polyamic acid, and interlayer insulating films using these, and more specifically, has excellent adhesion to various base materials, excellent heat resistance and low dielectric constant characteristics, and LSI (Large Scale). The present invention relates to an optimum polyimide 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]
In recent years, LSIs (Large Scale Integrated Circuits) have been steadily increasing in integration, multifunction, and performance due to advances in microfabrication technology. As a result, the circuit resistance and the capacitance between the wires (hereinafter referred to as “parasitic resistance” and “parasitic capacitance”, respectively) increase, which not only increases the power consumption, but also increases the delay time for the input signal. ing. Therefore, the increase in parasitic resistance and parasitic capacitance is a major factor that decreases the signal speed in LSI, and its solution is a major issue.
[0003]
Therefore, the interlayer insulating film in LSI is made of a low dielectric organic material, and the relative dielectric constant of the interlayer insulating film is lowered to improve 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 fluorine resin represented by polytetrafluoroethylene (PTFE) is used as a low dielectric organic material for an interlayer insulating film in LSI.
However, although such a fluororesin has a relatively low value of relative dielectric constant, there has been a problem that heat resistance and mechanical strength are insufficient as an organic material for an interlayer insulating film. Fluorine resin generally has poor adhesion to a substrate, and when used as an interlayer insulating film of an LSI, the interlayer insulating film is peeled off due to low adhesion to the substrate or wiring, resulting in long-term use in LSIs. There was also a problem of poor reliability.
[0004]
Also, the use of polyimide as an organic material for an interlayer insulating film of 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, which is still insufficient as an organic material for an interlayer insulating film of an LSI for increasing the signal speed. Polyimide also has poor adhesion to substrates, and in fields where high reliability is required under high temperatures and high humidity, such as semiconductor devices and circuit boards, the adhesion between polyimide and the substrate or wiring is low. There was a problem that the long-term reliability was poor due to the low level.
[0005]
Therefore, as a technique for improving adhesiveness, it has been proposed to introduce a siloxane bond into the main chain of polyimide (Japanese Patent Laid-Open Nos. 5-112760 and 9-255780, etc.).
However, although these polyimides are excellent in adhesiveness, the relative dielectric constant value exceeds 3 and there is a problem that they cannot be used for the use of an interlayer insulating film.
[0006]
[Problems to be solved by the invention]
The present invention has been completed by introducing an adamantane skeleton into the polyimide molecule.
That is, the present invention provides a polyimide having a low relative dielectric constant and excellent heat resistance, which is optimal as an interlayer insulating film in LSI, a polyamic acid as a precursor capable of forming the polyimide, and the polyimide. An object is to provide a polyimide varnish dissolved in a solvent.
[0007]
[Means for Solving the Invention]
[0008]
The present invention relates to 1,3-bis [4- (4-aminophenoxy) phenyl] adamantane or 3,3′-bis [4- (3-aminophenoxy) phenyl] -1,1′-biadamantane, and cyclic A polyamic acid obtained by polycondensation of an aliphatic tetracarboxylic dianhydride in an organic solvent, preferably a polyamic acid comprising a repeating unit represented by the following general formula (4), 3-bis [4- (4-aminophenoxy) phenyl] adamantane or 3,3′-bis [4- (3-aminophenoxy) phenyl] -1,1′-biadamantane and two cyclic aliphatic tetracarboxylic acids Polyimide obtained by dehydrating cyclization and imidization of polyamic acid obtained by polycondensation of an anhydride with an organic solvent , preferably the following general The present invention provides an interlayer insulating film comprising a polyimide comprising the repeating unit represented by the formula (2) and the polyamic acid.
General formula (4)
[Chemical 8]

(Wherein X represents a tetravalent cyclic aliphatic group)
General formula (2)
[Chemical 6]

(Wherein X represents a tetravalent cyclic aliphatic group)
[0009]
The polyamic acid of the present invention is 1,3-bis [4- (4-aminophenoxy) phenyl] adamantane (general formula (5)) or 3,3′-bis [4- (3-aminophenoxy) phenyl] -1 , 1′-biadamantane and cycloaliphatic tetracarboxylic dianhydride can be produced by polycondensation in an organic solvent.
General formula (5)
[Chemical 9]

[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 dianhydride, bicyclo [2.2.1] heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.1] heptane-2,3,5-tricarboxyacetic acid 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 and the like.
1,3-bis [4- (4-aminophenoxy) phenyl] adamantane or 3,3′-bis [4- (3-aminophenoxy) phenyl] -1,1′-biadamantane and cycloaliphatic tetracarboxylic acid The dianhydride is reacted with approximately equimolar amounts, and the reaction temperature is about 50 to 90 ° C.
[0011]
In addition, 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 production conditions. It is preferable to be 0.3 to 2 dl / g.
In addition, by adjusting the said manufacturing conditions suitably, in the polyamic acid obtained, the imidation ratio may be partially imidized within the range which does not exceed 50%.
The polyimide of the present invention can be produced by dehydrating and ring-closing and imidizing the above-described polyamic acid. In the imidization, a heat imidization method or a chemical imidization method as described below can be employed.
[0012]
(1) Heat imidization method
(A) A method of casting and heating a polyamic acid solution on a surface-smooth substrate such as glass or metal, or
(B) A method of heating the polyamic acid solution as it is is applied.
[0013]
In the heating imidation method (A) , 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]
Moreover, in the heating imidation method of (B) , a polyimide is obtained as a powder thru | or solution by heating a polyamic acid solution. The heating temperature in this case is usually a value within the range of 80 to 300 ° C, preferably a value within the range of 100 to 250 ° C.
In addition, in the heat imidization method of (B) , in order to facilitate removal of by-product water, components that azeotrope with water and can be easily separated from water particularly outside the reaction system, such as benzene and toluene. It is also preferable that an aromatic hydrocarbon solvent such as xylene is present as a dehydrating agent.
In the heat imidization method of (B) , in order to promote dehydration ring closure, tertiary amines such as aliphatic tertiary amines such as trimethylamine, triethylamine, tripropylamine, tributylamine; N, N A catalyst such as aromatic tertiary amines such as dimethylaniline and N, N-diethylaniline; heterocyclic tertiary amines such as pyridine, quinoline and isoquinoline is preferably added. And it is preferable to make the addition amount of this catalyst into the value within the range of 10-400 weight part per 100 weight part of polyamic acids, for example.
Furthermore, in the heating imidization method of (B) , it is also preferable to heat in a phenolic solvent such as cresol or chlorophenol. Thus, by making polyamic acid react, it can be set as a polyimide in one step.
Moreover, when implementing the heating imidation method of (A) and (B) , in order to produce a reaction uniformly, it is preferable to use an organic solvent. For example, it is preferable to use the same organic solvent as the organic solvent used for the production of polyamic acid.
In addition, when the polyimide obtained by the heating 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, steam distillation or the like. This also applies to the case of polyimide obtained by the chemical imidization method.
(2) Chemical imidization method Next, the chemical imidation method for producing a polyimide is demonstrated. As this chemical imidization method, for example,
(C) A method of imidizing in a solution state using a ring-closing agent for dehydrating and cyclizing polyamic acid can be employed.
[0015]
This chemical imidation method (C) is characterized in that polyimide is obtained as a powder or a solution. Moreover, in this chemical imidation method, it is preferable to use a solvent, for example, the organic solvent similar to what is used for manufacture of a polyamic acid can be mentioned.
[0016]
Examples of the ring-closing agent used in the chemical imidation method (C) include acid anhydrides such as acetic anhydride, propionic anhydride, and butyric anhydride. These ring closure agents can be used alone or in combination of two or more.
In addition, the amount of the ring-closing agent used is usually preferably in the range of 2 to 100 mol, preferably in the range of 2 to 50 mol, per mol of the repeating unit represented by the general formula (2). A value is more preferable.
Further, the reaction temperature in the chemical imidization method of (C) is not particularly limited, but it is usually preferably set to a value within the range of 0 to 200 ° C.
Further, in the chemical imidation method of (C) , it is also preferable to use a tertiary amine as a catalyst as in the case of the heat imidization method.
[0017]
The polyimide of the present invention is used for applications other than the interlayer insulating film described above, for example, a passivation film (stress buffer film) in LSI, an α-ray blocking film, a flexographic printing plate cover lay film, a flexographic printing plate overcoat, etc. You can also.
Also, die bonding adhesives, lead-on-chip (LOC) adhesive tapes, lead frame fixing tapes, multilayer lead frame adhesive films, and the like can be given.
[0018]
When an interlayer insulating film made of polyimide is formed, a precursor or polyamic acid varnish or paste, a polyimide film or 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 polyamic acid varnish is cast between LSI layers, and an excess organic solvent in the varnish is removed under heating and / or under reduced pressure to form a thin film of the polyamic acid. Next, a method of heating under normal pressure or under pressure, for example, at a temperature in the range of 100 to 450 ° C., and dehydrating and ring-closing the polyamic acid to imidize to form an interlayer insulating film.
(B) A method in which a film-like polyimide is disposed between LSI layers and thermocompression bonded by heating at a temperature within a range of 100 to 450 ° C. under normal pressure or under pressure to form an interlayer insulating film.
[0020]
Moreover, as a method of acquiring polyimide in a film form, for example,
(C) A polyamic acid varnish is cast on a substrate that has been previously subjected to a mold release treatment, such as glass, Teflon (registered trademark), polyester, etc., and then gradually heated to remove the solvent while dehydrating and closing the ring. And imidizing to form a film.
(D) A method of forming polyimide powder into a film by an appropriate method such as press molding or injection molding.
(E) A method of forming a polyimide dry film having a thickness of several tens to several hundreds μm by casting the polyamic acid of the first invention or the varnish of the polyimide of the second invention on a substrate and then heating and drying. .
[0021]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this 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 introduction tube and a cold trap, bromine 48.8 mL (0.952 mol), aluminum foil 9.71 mg (0.36) The mixture was stirred at room temperature until the red light disappeared, and 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 reaction mixture was cooled with ice water, the reaction solution was poured into ice water, sodium bisulfite was added until the bromine color 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 completion of stirring, the mixture 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 1.40 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 stirring, the mixture was cooled to room temperature and poured into distilled water. After filtration, it 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 converted to dimethyl In addition to formamide / ethanol mixed solvent (275 mL), hydrazine monohydrate (82.4 mL) and 0.165 g of Pd—C (10%) were added thereto, 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, it was poured into distilled water, stirred for 1 hour, and filtered and dried. The product was further refluxed in ethanol for 1 hour, 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 stream 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 refluxing, the solution was filtered while hot, and the precipitated solid was filtered and dried, and then 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 under a nitrogen stream in a three-necked flask (100 mL) equipped with a nitrogen introduction tube and a cold trap (19.6 mmol) was added, and 28.1 mL (0.549 mol) of bromine was added thereto, followed by stirring at room temperature for 15 minutes. Thereafter, refluxing 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 sodium bicarbonate solution 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 resulting solid was recrystallized from 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.
Synthesis of (5-3) 3,3′-di- (4-hydroxyphenyl) -1,1′-biadamantane 4.33 g (10.1 mmol) of 3,3′-dibromo-1,1′-biadamantane ), 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 stirring, the mixture was washed twice with water (80 ° C.), filtered, and dried under reduced pressure. The obtained solid was recrystallized from ethyl acetate. Yield 4.00 g (yield 87%), mp 343-344 ° C. The structure was confirmed by ¹ H-NMR.
Synthesis of (5-4) 3,3′-bis [4- (3 (or 4) -nitrophenoxy) phenyl] -1,1′-biadamantane 3,3′-di- (4-hydroxyphenyl)- 1,1′-biadamantane 4.07 g (8.95 mmol), 1,3-dinitrobenzene (or 4-chloronitrobenzene) 3.29 g (19.6 mmol), potassium carbonate 2.71 g (19.6 mmol) ) Was added to DMF (122 mL) and stirred at 160 ° C. for 12 hours. After completion of stirring, the mixture was cooled to room temperature and poured into distilled water. After filtration, it was dried under reduced pressure. The obtained solid was recrystallized from DMAc. Yield 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]- 1,1′-biadamantane 5.15 g (7.39 mmol) was added to DMAc: ethanol = 3: 1 mixed solvent (172 mL), and hydrazine monohydrate (30 mL), Pd—C (10 %) 0.103 g was added 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, it was poured into distilled water, stirred for 1 hour, and filtered and dried. The obtained solid was recrystallized from DMAc. Yield 3.28 g (70% yield). The structure was confirmed by ¹ H-NMR.
[0023]
[Example 1]
0.56-g (1.01 mmol) of 1,3-bis [4- (4-aminophenoxy) phenyl] adamantane was 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 at room temperature for 7 hours and at 80 ° C for 23 hours in a nitrogen atmosphere. 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 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. Polyamic acid was heat-treated under a nitrogen stream at 70 ° C. for 2 hours, 160 ° C. for 1 hour, 250 ° C. for 30 minutes, and 300 ° C. for 1 hour to obtain a polyimide.
The IR spectrum was measured by Horiba FT-720. ¹ H NMR and ¹³ C-NMR were measured by Bruker DPX300 (300 MHz). Thermal analysis was measured by SeikoTG / DTA 6300. The refractive index was measured with 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. Further, imidization was performed under a nitrogen stream, and the structure was confirmed by IR spectrum.
[0024]
[Example 2]
Bicyclo [2.2.2] oct-7-ene-2,3 instead of 0.197 g (1.01 mmol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA); 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 polyamic acid and polyimide.
[Example 3]
Bicyclo [2.2.1] heptane-2-methanecarboxylic dianhydride (NDA) instead of 0.197 g (1.01 mmol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) ) Polymerization was carried out in the same manner as in Example 1 except that 1.01 mmol was used to obtain polyamic acid and polyimide.
[0025]
Evaluation Results The glass transition point of the polyimide obtained in Example 1 (in a nitrogen atmosphere, temperature rising temperature 10 ° C./min, DSC measurement) was not detected, the decomposition start temperature was 387 ° C., and the 5% weight loss temperature was 464. C., 100% weight loss temperature was 482.degree.
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). It was.
[0026]
[Example 4]
0.63 g (1.01 mmol) of 3,3′-bis [4- (3-aminophenoxy) phenyl] -1,1′-biadamantane was dissolved in NMP (3.38 g). 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 stirring, the mixture was filtered and dried under reduced pressure. Yield 80%. The structure was confirmed by IR spectrum. Thermal imidization was performed by heat treatment under a nitrogen stream at 70 ° C. for 2 hours, 160 ° C. for 1 hour, 250 ° C. for 30 minutes, and 300 ° C. for 1 hour.
Thermal analysis was measured by SeikoTG / DTA 6300. The refractive index was measured with a PC-2000 prism coupler.
The obtained polyimide has a glass transition temperature of 288 ° C., a 5% weight loss temperature of 472 ° C. and a 10% weight loss temperature of 489 ° C., which are relatively high heat resistance, and a relative dielectric constant converted from a refractive index. 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)

1,3-bis [4- (4-aminophenoxy) phenyl] adamantane or 3,3′-bis [4- (3-aminophenoxy) phenyl] -1,1′-biadamantane and cyclic aliphatic tetracarboxylic A polyamic acid obtained by polycondensing acid dianhydride in an organic solvent. The polyamic acid according to claim 1, comprising a repeating unit represented by the following general formula (4).
General formula (4)

(Wherein X represents a tetravalent cyclic aliphatic group) A polyimide obtained by dehydrating and ring-closing and imidizing the polyamic acid according to claim 1. It consists of a repeating unit represented by the following general formula (2), The polyimide of Claim 3 characterized by the above-mentioned.
General formula (2)

(Wherein X represents a tetravalent cyclic aliphatic group) An interlayer insulating film comprising the polyimide according to claim 3 or 4.

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