JP3810219B2 - Positive photosensitive resin composition - Google Patents

Description

【００３４】
【化２】

【００３５】
【化３】

【００３６】
その重合体の具体例としては、例えば下記（ａ−１）〜（ａ−１５）、（ｂ−１）〜（ｂ−７）で表される構造単位等の環状脂肪族炭化水素骨格構造を挙げることができる。また、本発明に係わる（Ａ）重合体は、下記（ｃ−１）〜（ｃ−４）で表される構造単位を共重合成分として含んでもよい。
【００３７】
【化４】

【００３８】
【化５】

【００３９】
【化６】

【００４０】
前記（ａ−１）〜（ａ−１５）、（ｂ−１）〜（ｂ−７）で表される構造単位において、Ａ、Ｂは、各々独立に、水素原子、水酸基、カルボキシル基、アルコキシカルボニル基、炭素数が１〜１０個の置換もしくは非置換の、アルキル基、アルコキシ基又はアルケニル基を表し、ＡとＢとが結合して環を形成してもよい。Ｘ、Ｙは、各々独立に、酸の作用により分解する基を表す。
前記式（ｂ−１）〜（ｂ−７）、（ｃ−１）〜（ｃ−４）においてＲは水素原子、メチル基等の炭素数１〜３個のアルキル基を表す。Ｚは水素原子、炭素数が１〜１０の置換もしくは非置換のアルキル基、アルコキシカルボニル基もしくは酸の作用により分解する基を表す。）
【００４１】
上記において、アルコキシカルボニル基としては、メトキシカルボニル基、エトキシカルボニル基、ブトキシカルボニル基等が挙げられる。
炭素数が１〜１０個のアルキル基としては、置換されていてもよい、直鎖、分岐あるいは環状アルキル基が挙げられ、具体的には、メチル基、エチル基、プロピル基、イソプロピル基、ｎ−ブチル基、ｔ−ブチル基、シクロペンチル基、シクロヘキシル基、ヒドロキシメチル基、ヒドロキシエチル基等が挙げられる。
炭素数が１〜１０個のアルコキシ基としては、メトキシ基、エトキシ基、ｎ−ブトキシ基、ｔ−ブトキシ基、プロポキシ基、イソプロポキシ基等が挙げられる。 炭素数が２〜１０個のアルケニル基としては、アリル基、ビニル基、２−プロペニル基等が挙げられる。
ＡとＢとが結合して形成する環としては、ＡとＢが結合して
−Ｃ（＝Ｏ）−Ｏ−Ｃ（＝Ｏ）−、
−Ｃ（＝Ｏ）−ＮＨ−Ｃ（＝Ｏ）−、
−ＣＨ₂ −Ｃ（＝Ｏ）−Ｏ−Ｃ（＝Ｏ）−、
等を形成して環となったものが挙げられる。
【００４２】
酸の作用により分解する基としては、−（ＣＨ₂ ）_n −ＣＯＯＲａ基もしくは−（ＣＨ₂ ）_n −ＯＣＯＲｂ基が挙げられる。ここでＲａは、炭素数２〜２０個の炭化水素基を表し、その炭化水素基としては、ｔ−ブチル基、ノルボルニル基、シクロデカニル基等が挙げられる。Ｒｂとしては、テトラヒドロフラニル基、テトラヒドロピラニル基、エトキシエチル基、イソプロピルエチル基等のアルコキシエチル基、ラクトン基、又はシクロヘキシロキシエチル基を表す。ｎは０又は１を表す。
【００４３】
上記各基における更なる置換基としては、ハロゲン原子、シアノ基、ニトロ基等が挙げられる。
【００４４】
上記式（ａ−１）〜（ａ−６）で示される構造単位からなる重合体（Ａ）は、例えば環状オレフィン類をメタセシス触媒の存在下、有機溶媒中、あるいは非有機溶媒中で開環重合し、引き続き水素化することによって得られる。開環(共)重合は、例えばW.L.Truettら;J.Am.Chem.Soc.,82,2337(1960)、A.Pacreau;Macromol.Chem.,188,2585(1987)、特開昭５１−３１８００号、特開平１−１９７４６０号、特開平２−４２０９４号、ＥＰ−０７８９２７８号等に記載の合成方法により容易に重合できる。ここで用いられるメタセシス触媒としては、例えば高分子学会編:高分子の合成と反応(1),共 立出版p375-381(1992)、特開昭４９−７７９９９号に記載の化合物、具体的にはタングステン及び又はモリブデン系等の遷移金属のハロゲン化合物と有機アルミニウム化合物又はこれらと第三成分とからなる触媒系を挙げることができる。
【００４５】
上記タングステン及びモリブデン化合物の具体例としては、五塩化モリブデン、六塩化タングステン及びタングステンオキシテトラクロライドが挙げられ、有機アルミニウム化合物としては、トリエチルアルミニウム、トリイソブチルアルミニウム、トリヘキシルアルミニウム、ジエチルアルミニウムモノクロライド、ジ−ｎ−ブチルアルミニウムモノクロライド、エチルアルミニウムセスキクロライド、ジエチルアルミニウムモノブトオキサイド及びトリエチルアルミニウム−水（モル比１：０．５）が挙げられる。開環重合をおこなうにあたり、上記タングステン又はモリブデン化合物1モルに対する有機アルミニウム化合物の使用割 合は０．５モル以上が好ましい。
触媒の重合活性等を向上させるための第三成分としては、水、過酸化水素、酸素含有有機化合物、チッソ含有有機化合物、ハロゲン含有有機化合物、リン含有有機化合物、硫黄含有有機化合物、金属含有有機化合物が挙げられ、タングステン又はモリブデン化合物1モルに対して５モル以下の割合で併用される。単量体 に対する触媒の使用割合は、それらの種類にもよるが通常、単量体１００モルに対して０．１〜２０モルの割合で使用される。
【００４６】
開環(共)重合における重合温度は−４０℃〜＋１５０℃が好ましく、不活性ガス雰囲気中で行うのが望ましい。使用される溶媒としては、ペンタン、ヘキサン、ヘプタン、オクタン等の脂肪族炭化水素；シクロペンタン、シクロヘキサン等の脂環族炭化水素；ベンゼン、トルエン、キシレン等の芳香族炭化水素；塩化メチレン、１，１−ジクロロエタン、１，２−ジクロロエチレン、１−クロロプロパン、１−クロロブタン、１−クロロペンタン、クロロベンゼン、ブロムベンゼン、ｏ−ジクロロベンゼン、ｍ−ジクロロベンゼン等のハロゲン化炭化水素；ジエチルエーテル、テトラヒドロフラン等のエーテル系化合物が挙げられる。
【００４７】
このような開環(共)重合により得られた重合体を水素化することにより、本発明に用いられる重合体（Ａ）が得られる。水素化反応において用いられる触媒は通常のオレフィン性化合物の水素添加反応に用いられている不均一触媒あるいは均一触媒を使用することができる。
不均一触媒としては、例えばパラジウム、白金、ニッケル、ルテニウム、ロジウム等の貴金属触媒をカーボン、シリカ、アルミナ、チタニア等の担体に担持させた固体触媒等が挙げられる。また均一触媒としては、例えばナフテン酸ニッケル/トリエチルアルミニウム、ニッケルアセチルアセトナート/トリエチルアルミニウム、オクテン酸コバルト/n-ブチルリチウム、チタノセンジクロリド/ジエチルアルミニウムモノクロリド、酢酸ロジウム、クロロトリス(トリフェニ ルホスフィン)ロジウム等のロジウム触媒を挙げることができる。
これらの触媒のうち、不均一触媒は、反応活性が高く、反応後の触媒除去も容易であり、得られる重合体が着色しないので好都合である。
【００４８】
水素化反応は、常圧〜３００気圧、好ましくは３〜２００気圧の水素ガス雰囲気下において、０〜２００℃、好ましくは２０〜１８０℃で行うことができる。水素添加率は通常５０％以上、好ましくは７０％以上、さらに好ましくは８０％以上である。水素添加率が５０％未満の場合には、レジストの熱安定性や経時安定性を悪化させるので好ましくない。
【００４９】
上記式（ａ−７）〜（ａ−１５）で示される構造単位からなる重合体は、例えばフリーラジカル重合開始剤の有効量の存在下に、環状脂肪族炭化水素モノマーのラジカル(共)重合により合成できる。具体的には、J.Macromol.Sci.Chem.A-5 (3)491(1971)、同A-5(8)1339(1971)、Polym.Lett.Vol.2,469(1964)、ＵＳＰ３１４３５３３号、ＵＳＰ３２６１８１５号、ＵＳＰ３５１０４６１号、ＵＳＰ３７９３５０１号、ＵＳＰ３７０３５０１号、特開平２−１４６０４５号記載の方法により合成できる。
ラジカル(共)重合に用いられる好ましい開始剤は２，２’−アゾビス（２−メチルプロパンニトリル）や過酸化ベンゾイル，過酸化ジクミル等を挙げることができる。開始剤の濃度は、単量体の総重量に対して、通常０．０１〜１０重量％、好ましくは０．１〜５重量％である。重合温度は広範囲に変えられ、通常室温〜２５０℃の範囲、好ましくは４０〜２００℃の範囲、さらに好ましくは６０〜１６０℃の範囲で重合が行われる。
【００５０】
重合もしくは共重合は、有機溶剤中で行なうのが好ましい。所定の温度で単量体を溶解し、また生成重合体をも溶解する溶剤が好ましい。好ましい溶剤は共重合する単量体の種類によつても変わるが、例えばトルエン等の芳香族炭化水素類；酢酸エチル等の脂肪族；芳香族エステル類；テトラヒドロフラン等の脂肪族エーテル類を挙げることができる。
所定時間反応後、得られた重合体と未反応の単量体成分、溶剤等を分離する目的で減圧蒸留、精製を行うのが好ましい。
【００５１】
（ｂ−１）〜（ｂ−７）の構造単位を有する重合体、あるいは共重合成分（ｃ−１）〜（ｃ−４）を含むものは、フリーラジカル開始剤の有効量存在下でラジカル（共）重合により合成できる。
重合体（Ａ）中、環状脂肪族骨格を有する構造単位の含有量は、全構造単位の１０モル％以上が好ましく、より好ましくは２０モル％以上、さらに好ましくは３０モル％以上である。
また、重合体（Ａ）中、酸分解性基を有する構造単位の含有量は、全構造単位の１０〜９０モル％であり、好ましくは１５〜８５モル％、さらに好ましくは２０〜８０モル％である。
また、本発明に用いられる重合体中、（ｃ−１）〜（ｃ−４）で表される単位等の他の共重合成分の含有量は全単量体の繰り返し単位中３〜６０モル%が好ま しく、より好ましくは５〜５５モル%、さらに好ましくは１０〜５０モル%である。
【００５２】
重合体（Ａ）は、重量平均分子量が１５００〜１０００００の範囲にあることが好ましく、さらに好ましくは２０００〜７００００の範囲、特に好ましくは３０００〜５００００の範囲である。分子量が１５００未満では耐ドライエッチング耐性，耐熱性，基板との密着性が不十分であり、分子量が１０００００を越えるとレジスト感度が低下するため好ましくない。また、分子量分布（Ｍｗ／Ｍｎ）は好ましくは１．０〜６．０、より好ましくは１．０〜４．０であり小さいほど耐熱性、画像性能（レジストプロファイル、デフォーカスラチチュード等）が良好となる。
なお、重合（Ａ）の重量平均分子量及び分子量分布（Ｍｗ／Ｍｎ）は、屈折率検知器をつけたゲルパーミエーションクロマトグラフィーで、ポリスチレン換算値として測定される。
【００５３】
本発明のポジ型感光性樹脂組成物において、重合体（Ａ）の含有量は、固形分換算で、５０〜９９．７重量％、好ましくは７０〜９９重量％である。
本発明のポジ型感光性樹脂組成物は、重合体（Ａ）以外に、必要により他のポリマーを含有することができる。他のポリマーの含有量は、重合体（Ａ）１００重量部あたり、好ましくは３０重量部以下、さらに好ましくは２０重量部以下、特に好ましくは１０重量部以下である。
【００５４】
本発明のポジ型感光性樹脂組成物が含有することができる上記他のポリマーとして、本発明の脂環式ポリマーと相溶するものであればよく、ポリｐ−ヒドロキシエチレン、水素化ポリｐ−ヒドロキシエチレン、ノボラック樹脂等を挙げることができる。
【００５５】
次に、本発明のポジ型感光性樹脂組成物に含有される(Ｂ)活性光線の照射により分解して酸を発生する化合物(以下、「（Ｂ）光酸発生剤」ともいう)について説明する。
本発明で使用される（Ｂ）光酸発生剤の例としては、光カチオン重合の光開始剤、光ラジカル重合の光開始剤、色素類の光消色剤、光変色剤、又は紫外線、遠紫外線、ＫｒＦエキシマレーザー光、ＡｒＦエキシマレーザー光、電子線、X線 、分子線、イオンビーム等により酸を発生するマイクロフォトレジストで公知の光酸発生剤及びそれらの混合物を適宜に選択して使用することができる。
なお、本発明においては、活性光線は、上記した如く放射線を包含する広い概念で用いられる。
【００５６】
（Ｂ）光酸発生剤は、本発明のポジ型感光性樹脂組成物に用いられる後述の有機溶剤に溶解するものであれば特に制限されないが、２２０ｎｍ以下の光で酸を発生する光酸発生剤であることが好ましい。また、単独でもしくは2種以上を組 み合わせ用いてもよく、適当な増感剤と組み合わせて用いてもよい。
【００５７】
使用可能な（Ｂ）光酸発生剤の例としては、例えばJ.Org.Chem.Vol.43,N0.15,3055(1978)に記載のトリフェニルスルホニウム塩誘導体及び特願平9-279071号に記載の他のオニウム塩(スルホニウム塩、ヨードニウム塩、ホスホニウム塩、ジ アゾニウム塩、アンモニウム塩)も用いることができる。
オニウム塩の具体例としては、ジフェニルヨードニウムトリフレート、ジフェニルヨードニウムピレンスルホネート、ジフェニルヨードニウムドデシルベンゼンスルホネート、トリフェニルスルホニウムトリフレート、トリフェニルスルホニウムヘキサフルオロアンチモネート、ジフェニルヨードニウムヘキサフルオロアンチモネート、トリフェニルスルホニウムナフタレンスルホネート、トリフェニルスルホニユムカンファースルホニウム、（４−メトキシフェニル）フェニルヨードニウムトリフルオロメタンスルホネート、ビス（ｔ−ブチルフェニル）ヨードニウムトリフルオロメタンスルホネート等を挙げることができる。
【００５８】
また、特開平３−１０３８５４号、特開平３−１０３８５６号、特開平４−１２１０９６０号で示される ジアゾジスルホン類やジアゾケトスルホン類、特開 昭６４−１８１４３号、特開平２−２４５７５６号に記載のイミノスルホネート類、特開平２−７１２７０号に記載のジスルホン類も 好適に用いることができ る。さらに、ＵＳＰ３８４９１３７号、特開昭６３−２６６５３号、特開昭６２−６９２６３号、特開昭６３−１４６０３８号、特開昭６３−１６３４５２号、特開昭６２−１５３８５３号、特開 昭６３−１４６０２９号等に記載の光によ り酸を発生する基をポリマーの主鎖もしくは側 鎖に導入した化合物も用いるこ とができ、特開平７−２５８４６号、特開平７−２８２３７号、特開平７−９２６７５号、特開平８−２７１２０号記載の２−オキソシクロヘキシル基を有する脂肪族アルキルスルホニウム塩類、及びＮ−ヒドロキシスクシンイミドスルホネート類、さらにはJ.Photopolym.Sci.,Tech.,Vol.7,No.3,423(1994)に記載のスルホニウム塩等も好適に用いることができ、単独でもしくは2種以上の組み合わ せで用いられる。
【００５９】
これらの（Ｂ）活性光線の照射により分解して酸を発生する化合物の含有量は、感光性樹脂組成物の全重量(固形分)を基準として、通常０．００１〜４０重量％、好ましくは０．０１〜２０重量％、さらに好ましくは０．１〜５重量％である。（Ｂ）光酸発生剤の量が０．００１重量％より少ないと感度が低くなり、４０重量％より多いとレジストの光吸収が高くなりすぎプロファイルの劣化やプロセスマージン、特にベークマージンが狭くなり好ましくない。
【００６０】
次に本発明のポジ型感光性樹脂組成物に含有される（Ｃ）含窒素塩基性化合物について説明する。（Ｃ）含窒素塩基性化合物としては、有機アミン、塩基性のアンモニウム塩、塩基性のスルホニウム塩が、感度、解像力、プロファイルが優れる点で好ましく用いられるが、昇華やレジスト性能を劣化させないものであればよい。
例えば特開昭６３−１４９６４０号、特開平５−２４９６６２号、特開平５−１２７３６９号、特開平５−２８９３２２号、特開平５−２４９６８３号、特開平５−２８９３４０号、特開平５−２３２７０６号、特開平５−２５７２８２号、特開平６−２４２６０５号、特開平６−２４２６０６号、特開平６−２６６１００号、特開平６−２６６１１０号、特開平６−３１７９０２号、特開平７−１２０９２９号、特開平７−１４６５５８号、特開平７−３１９１６３号、特開平７−５０８８４０号、特開平７−３３３８４４号、特開平７−２１９２１７号、特開平７−９２６７８号、特開平７−２８２４７号、特開平８−２２１２０号、特開平８−１１０６３８号、特開平８−１２３０３０号、特開平９−２７４３１２号、特開平９−１６６８７１号、特開平９−２９２７０８号、特開平９−３２５４９６号、特表平７−５０８８４０号、ＵＳＰ５５２５４５３号、ＵＳＰ５６２９１３４号、ＵＳＰ５６６７９３８号等に記載の塩基性化合物を用いることができる。
【００６１】
特に好ましくは、１，５−ジアザビシクロ［４．３．０］−５−ノネン、１，８−ジアザビシクロ［５．４．０］−７−ウンデセン、１，４−ジアザビシクロ［２．２．２］オクタン、４−ジメチルアミノピリジン、１−ナフチルアミン、ピペリジン、ヘキサメチレンテトラミン、イミダゾール類、ヒドロキシピリジン類、ピリジン類、４，４’−ジアミノジフェニルエーテル、ピリジニウムｐ−トルエンスルホナート、２，４，６−トリメチルピリジニウムｐ−トルエンスルホナート、テトラメチルアンモニウムｐ−トルエンスルホナート、及びテトラブチルアンモニウムラクテート等が挙げられる。
（Ｃ）塩基性化合物は、１種単独であるいは２種以上を組み合わせて用いることができる。
【００６２】
（Ｃ）含窒素塩基性化合物の含有量は、感光性樹脂組成物（固形分）１００重量部に対し、通常、０．００１〜１０重量部、好ましくは０．０１〜５重量部である。０．００１重量部未満では効果が十分得られない。一方、１０重量部を越えると感度の低下や非露光部の現像性が著しく悪化する傾向がある。
【００６３】
次に本発明のポジ型感光性樹脂組成物に含有される（Ｄ）フッ素系及び／又はシリコン系界面活性剤について説明する。
本発明の感光性樹脂組成物には、フッ素系界面活性剤、シリコン系界面活性剤、フッ素原子とシリコン原子の両方を有する界面活性剤、あるいはこれらの２種以上の混合物を含有することができる。
これらの（Ｄ）界面活性剤として、例えば特開昭６２−３６６６３号、特開昭６１−２２６７４６号、特開昭６１−２２６７４５号、特開昭６２−１７０９５０号、特開昭６３−３４５４０号、特開平７−２３０１６５号、特開平８−６２８３４号、特開平９−５４４３２号、特開平９−５９８８号記載の界面活性剤 を挙げることができ、下記市販の界面活性剤をそのまま用いることもできる。
使用できる市販の界面活性剤として、例えばエフトップＥＦ３０１、ＥＦ３０３、（新秋 田化成（株）製）、フロラードＦＣ４３０、４３１（住友スリーエ ム（株）製）、メガファックＦ１７１、Ｆ１７３、Ｆ１７６、Ｆ１８９、Ｒ０８（大日本インキ（株）製）、サーフロンＳ−３８２、ＳＣ１０１、１０２、１０３、１０４、１０５、１０６（旭硝子（株）製）等のフッ素系界面活性剤又はシリコン系界面活性剤を挙げることができる。またポリシロキサンポリマーＫＰ−３４１（信越化学工業（株）製）もシリコン系界面活性剤として用いることができ る。
これらの界面活性剤のうち、フッ素原子とシリコン原子の両方を有する界面活性剤が、現像欠陥の改善の点で特に優れる。
【００６４】
（Ｄ）界面活性剤の配合量は、本発明の組成物中の固形分１００重量部当たり、通常０．０１重量部〜２重量部、好ましくは０．０１重量部〜１重量部である。
これらの界面活性剤は１種単独であるいは２種以上を組み合わせて用いることができる。
【００６５】
本発明のポジ型感光性樹脂組成物は、必要に応じて、分子量が２０００以下であって、酸の作用により分解し得る基を有し、アルカリ溶解性が酸の作用により増大する低分子酸分解性化合物を含むことができる。
例えばProc.SPIE,2724, 355(1996)、特開平８−１５８６５号、ＵＳＰ５３１ ０６１９号、ＵＳＰ−５３７２９１２号、J.Photopolym.Sci.,Tech.,Vol.10,No.3,511(1997))に記載されている酸分解性基を含有するコール酸誘導体、デヒドロコール酸誘導体、デオキシコール酸誘導体、リトコール酸誘導体、ウルソコール酸誘導体、アビエチン酸誘導体等の脂環族化合物、酸分解性基を含有するナフタレン誘導体等の芳香族化合物を上記低分子酸分解性化合物として用いることができる。
さらに、特開平６−５１５１９号記載の低分子の酸分解性溶解阻止化合物も２２０ｎ ｍの透過性を悪化させないレベルの添加範囲で用いることもできるし、 １，２−ナフトキノンジアジト化合物も使用できる。
本発明の感光性樹脂組成物に上記低分子酸分解性溶解阻止化合物を使用する場合、その含有量は感光性樹脂組成物の全重量(固形分)を基準として、通常１〜５０重量%の範囲で用いられ、好ましくは３〜４０重量%、さらに好ましくは５〜３０重量%の範囲で使用される。
これらの低分子酸分解性溶解阻止化合物を添加すると、前記現像欠陥がさらに改良されるばかりか耐ドライエッチング性が改良される。
【００６６】
次に本発明に用いられる（Ｅ）溶剤について説明する。
本発明に用いられる（Ｅ）溶剤は、（ａ）乳酸エチルと（ｂ）３−エトキシプロピオン酸エチルを含有する。主溶媒である（ａ）乳酸エチルは、（Ｅ）溶剤中、６０〜９０重量％の範囲、好ましくは６０〜８５重量％の範囲、さらに好ましくは６５〜８０重量％の範囲で用いられる。
（ａ）乳酸エチルと併用される溶媒である（ｂ）３−エトキシプロピオン酸エチルは、溶剤中、１０〜４０重量％の範囲で用いられ、好ましくは１０〜３０重量％の範囲、さらに好ましくは１０〜２５重量％の範囲で用いられる。
（ａ）乳酸エチルと（ｂ）３−エトキシプロピオン酸エチルの総和は、（Ｅ）溶剤中、７０重量％以上占めることが好ましく、７０重量％未満では、本発明の目的が十分達成できない場合がある。
【００６７】
また、本発明では、上記（ａ）及び（ｂ）以外の溶媒として、沸点（ｂ．ｐ．）が１８０℃以上、好ましくは１８５℃以上の範囲にあり、かつ溶解度パラメーター（ＳＰ値）が１２以上、好ましくは１２．４以上の範囲にある（ｃ）溶媒を、（Ｅ）溶剤中に１〜２０重量％、好ましくは３〜１５重量％含有することが好ましい。
このような（ｃ）溶媒を併用することにより、現像欠陥が飛躍的に向上する。但し、２０重量％を超える量混合すると基板との密着性が悪化するので好ましくない。
このような（ｃ）溶媒の具体例としては、γ−ブチロラクトン（ｂ．ｐ．＝１９０℃，ＳＰ値＝１２．６）、プロピレンカーボネート（ｂ．ｐ．＝２４２℃，ＳＰ値＝１３．３）、エチレンカーボネート（ｂ．ｐ．＝２３９℃，ＳＰ値＝１４．７）、Ｎ，Ｎ−ジメチルイミダゾリノン（ｂ．ｐ．＝２００℃，ＳＰ値＝１２．４）、ジメチルスルホキシ ド（ｂ．ｐ．＝１８９℃，ＳＰ値＝１３．０） 等が挙げられる。これらのうち、特にγ−ブチロラクトン、プロピレンカーボネート、エチレンカーボネートが本発明の効果を発現する上で特に好ましい。
これらの（ｃ）溶媒は、１種単独であるいは２種以上を組み合わせて用いることができる。
【００６８】
本発明の（Ｅ）溶剤には上記溶媒を用いることが好ましいが、本発明の効果を損なわない範囲で、好ましくは５重量％以下の量で、他の溶媒をさらに含有させることができる。
使用できる他の溶剤としては、シクロヘキサノン、２−ヘプタノン、プロピレングリコールモノメチルエーテル、プロピレングリコールモノメチルエーテルアセテート、プロピレングリコールモノメチルエーテルプロピオネート、プロピレングリコールモノエチルエーテルアセテート、３−メトキシプロピオン酸メチル、β−メトキシイソ酪酸メチル、酪酸エチル、酪酸プロピル、メチルイソブチルケトン、酢酸エチル、酢酸イソアミル、ジアセトンアルコール、Ｎ−メチルピロリドン等が挙げられる。
【００６９】
本発明のポジ型感光性樹脂組成物には、必要に応じて、さらに現像液に対する溶解促進性化合物、ハレーション防止剤、可塑剤、界面活性剤、光増感剤、接着助剤、架橋剤、光塩基発生剤等を含有することができる。
【００７０】
本発明で使用できる現像液に対する溶解促進性化合物の例としては、例えば特開平３−２０６４５８号記載のフェノール性水酸基を２個以上含有する化合物、１−ナフトール等のナフトール類又はカルボキシル基を１個以上有する化合物、カルボン酸無水物、スルホンアミド化合物やスルホニルイミド化合物等の分子量１０００以下の低分子化合物等を挙げることができる。
これらの溶解促進性化合物の配合量としては、組成物全重量(固形分)に対して、好ましくは３０重量％以下、より好ましくは２０重量％以下である。
【００７１】
好適なハレーション防止剤としては、照射する放射線を効率よく吸収する化合物が好ましく、フルオレン、９−フルオレノン、ベンゾフェノンのような置換ベンゼン類；アントラセン、アントラセン−９−メタノール、アントラセン−９−カルボキシエチル、フェナントレン、ペリレン、アジレンのような多環式芳香族化合物等が挙げられる。なかでも、多環式芳香族化合物が特に好ましい。これらのハレーション防止剤は基板からの反射光を低減し、レジスト膜内の多重反射の影響を少なくさせることで、定在波改良の効果を発現する。
【００７２】
本発明の感光性樹脂組成物の塗布性を改良したり、現像性を改良する目的で、ノニオン系界面活性剤を併用することができる。
併用できるノニオン系界面活性剤として、ポリオキシエチレンラウリルエーテル、ポリオキシエチレンステアリルエーテル、ポリオキシエチレンオクチルフェニルエーテル、ポリオキシエチレンノニルフェニルエーテル、ポリエチレングリコールジラウレート、ポリエチレングリコールジステアレート、ポリオキシエチレンソルビタンモノステアレート、ソルビタンモノラウレート等が挙げられる。
【００７３】
また露光による酸発生率を向上させるために、光増感剤を添加することができる。好適な光増感剤として、ベンゾフェノン、ｐ,ｐ'−テトラメチルジアミノベンゾフェノン、２−クロロチオキサントン、アントロン、９−エトキシアントラセン、ピレン、フェノチアジン、ベンジル、ベンゾフラビン、アセトフェノン、フェナントレン、ベンゾキノン、アントラキノン、１，２−ナフトキノン等を挙げることができるが、これらに限定されるものではない。これらの光増感剤は前記ハレーション防止剤としても使用可能である。
【００７４】
さらに本発明の感光性樹脂組成物は、メタル等の金属不純物やクロルイオン等の不純物成分を１００ｐｐｂ以下に低減しておくことが好ましい。これらの不純物が多く存在すると、半導体デバイスを製造する上で動作不良、欠陥、収率低下を招いたりするので好ましくない。
【００７５】
本発明の感光性樹脂組成物を基板上にスピナー、コーター等の適当な塗布方法により塗布後、プリベーク（露光前加熱）し、所定のマスクを通して２２０ｎｍ以下の波長の露光光で露光し、ＰＥＢ（露光後ベーク）を行い現像することにより良好なレジストパターンを得ることができる。
ここで用いられる基板としては半導体装置その他の製造装置において通常用いられる基板であればよく、例えばシリコン基板、ガラス基板、非磁性セラミックス基板等が挙げられる。また、これらの基板上にさらに必要に応じて追加の層、例えばシリコン酸化物層、配線用金属層、層間絶縁膜、磁性膜、反射防止膜層等が存在してもよく、また各種の配線、回路等が作り込まれていてもよい。さらにまた、これらの基板はレジスト膜の密着性を高めるために、常法に従って疎水化処理されていてもよい。適当な疎水化処理剤としては、例えば１，１，１，３，３，３−ヘキサメチルジシラザン（ＨＭＤＳ）等が挙げられる。
【００７６】
基板上に塗布されるレジスト膜厚は、約０．１〜１０μｍの範囲が好ましく、ＡｒＦ露光の場合は、約０．１〜１．５μｍ厚が推奨される。
基板上に塗布されたレジスト膜は、約６０〜１６０℃の温度で約３０〜３００秒間プリベークするのが好ましい。プリベークの温度が低く、時間が短かければレジスト膜中の残留溶剤が相対的に多くなり、密着性が劣化する等の弊害を生じるので好ましくない。また、逆にプリベークの温度が高く、時間が長ければ、感光性樹脂組成物のバインダー、光酸発生剤等の構成成分が分解する等の弊害が生じるので好ましくない。
【００７７】
プリベーク後のレジスト膜を露光する装置としては市販の紫外線露光装置、Ｘ線露光装置、電子ビーム露光装置、ＫｒＦエキシマ露光装置、ＡｒＦエキシマ露光装置、Ｆ₂エキシマ露光装置等が用いられ、特に本発明ではＡｒＦエキシマレーザーを露光光源とする装置が好ましい。
露光後ベークは酸を触媒とする保護基の脱離を生じさせる目的や定在波を消失させる目的、酸発生剤等を膜中に拡散させる目的等で行われる。この露光後ベークは先のプリベークと同様にして行うことができる。例えば、ベーキング温度は約６０〜１６０℃、好ましくは約９０〜１５０℃である。
【００７８】
本発明の感光性樹脂組成物の現像液としては水酸化ナトリウム、水酸化カリウム、炭酸ナトリウム、ケイ酸ナトリウム、アンモニア水等の無機アルカリ類、エチルアミン、ｎ−プロピルアミン等の第一アミン類、ジエチルアミン、ジ−ｎ−ブチルアミン等の第２アミン類、トリエチルアミン、メチルジエチルアミン等の第３アミン類、ジメチルエタノールアミン、トリエタノールアミン等のアルコールアミン類、水酸化テトラメチルアンモニウム（ＴＭＡＨ）、水酸化テトラエチルアンモニウム（ＴＥＡＨ）、トリメチルヒドロキシメチルアンモニウムヒドロキシド、トリエチルヒドロキシメチルアンモニウムヒドロキシド、トリメチルヒドロキシエチルアンモニウムヒドロキシド等の第４級アンモニウム塩、ピロール、ピペリジン、１，８−ジアザビシクロ−［５．４．０］−７−ウンデセン、１，５−ジアザビシクロ−［４．３．０］−５−ノナン等の環状アミン類等のアルカリ水溶液を使用することができる。
【００７９】
さらに、上記アルカリ性水溶液にアルコール類やケトン類等の親水性の有機溶剤やノニオン系や陰イオン性界面活性剤及び陽イオン性界面活性剤や消泡剤等を適当量添加しても使用することができる。これらの添加剤は、レジストの性能を向上させる目的以外にも基板との密着性を高めたり、現像液の使用量を低減させたり、現像時の気泡に起因する欠陥を低減させる目的等でアルカリ性水溶液に添加される。
【００８０】
【実施例】
以下、本発明を実施例によりさらに詳細に説明するが、本発明がこれにより限定されるものではない。
【００８１】
合成例１（重合体Ａの合成）
特開平９−２４４２４７号公報、第４例に記載のノルボルネン誘導体の開環重合体の水素化物(繰り返し構造単位を下記する)を、ＥＰ０７８９２７８号明細書記載の方法に従って合成した（重量平均分子量２２０００）。
【００８２】
【化７】

【００８３】
合成例２（重合体Ｂの合成）
特開平９−２４４２４７号公報、第１例に記載のノルボルネン誘導体の開環重合体の水素化物(繰り返し構造単位を下記する)をＥＰ０７８９２７８号明細書記載の方法に従って合成した（重量平均分子量１７０００）。
【００８４】
【化８】

【００８５】
合成例３（重合体Ｃの合成）
ノルボルネン、無水マレイン酸、アクリル酸ｔ−ブチル及びアクリル酸の共重合体(繰り返し構造単位を下記する)を特開平１０−１０７３９号公報、第７例に記載の方法に従って合成した（重量平均分子量１７０００、各繰り返し単位のモル比５０／２５／２５）
【００８６】
【化９】

【００８７】
合成例４（重合体Ｄの合成）
メタクリル酸アダマンチルとアクリル酸ｔ−ブチルの共重合体(繰り返し構造 単位を下記する)を特開平７−２３４５１１号公報、第１例に記載の方法に従っ て合成した（重量平均分子量５０００、各繰り返し単位のモル比５８／４２）。
【００８８】
【化１０】

【００８９】
合成例５（酸分解性低分子化合物ａの合成）
コール酸１２２．７ｇ（０．３モル）とチオニルクロライド１２０ｍｌの混合物を１時間還流した。過剰のチオニルクロリドを除去し、得られた固体をテトラヒドロフラン１５０ｍｌに溶かし、カリウム−ｔ−ブシトキシド４０ｇ（０．３５モル）を徐々に加え、反応混合物を６時間還流した後、冷却し、水中に注いだ。得られた固体を濾過して集め、水で洗い減圧下で乾燥した。この粗製物をｎ−ヘキサンで再結晶し７０％の収率でコール酸ｔ−ブチル（下記式）を得た。
【００９０】
【化１１】

【００９１】
合成例６（重合体Ｅの合成）
特開平６−３０８７３４号の合成例１に従い重合体Ｅを合成した。即ち、ポリヒドロキシスチレン３０ｇをテトラヒドロフランに溶解して、ｔ−ブトキシカリウム１０ｇを添加し、攪拌下、０℃においてジ−ｔ−ブチルジカーボネート６０ｇを滴下し、４時間反応させた。反応終了後、この溶液を水中に滴下し、析出した樹脂を真空乾燥器にて５０℃で一晩乾燥した。得られた樹脂（重合体Ｅ）は、Ｍｗが１５０００で、ＮＭＲ測定の結果からフェノール性水酸基の水素原子の２９％がｔ−ブトキシカルボニル基で置換された構造であった。
【００９２】
実施例１〜７、比較例１〜７
（感光性樹脂組成物の調製）
感光性樹脂成分を調製するに当たって、表１に記載した成分、即ち、合成例１〜４及び６で合成した重合体Ａ、Ｂ、Ｃ、Ｄ、及びＥ、光酸発生剤としてトリフェニルスルホニウムトリフレート（ＰＡＧ−１）、合成例５で合成した酸分解性低分子化合物( 化合物ａ)、含窒素塩基性化合物、界面活性剤、及び溶剤の各成分を用いた。表１ で点線が付されているものは、その成分を用いなかったことを意味する。
各成分を混合後、０．１μｍのテフロンフィルターにより濾過して感光性樹脂組成物を調製した。
用いられた場合の各成分の量は、下記の通りである。
重合体Ａ，Ｂ，Ｃ，Ｄ,Ｅ １０ｇ
光酸発生剤 ０．０６ｇ
酸分解性低分子化合物 ０．２５ｇ
含窒素塩基性化合物 ０．０４ｇ
界面活性剤 ０．０５ｇ
溶剤 ５７．４ｇ
【００９３】
このように調整された感光性樹脂組成物につき、下記方法により現像欠陥数を調べた。評価結果を表２に示した。
（現像欠陥数の評価方法）
（１）現像欠陥数−Ｉ
感光性樹脂組成物をスピンコーターによりヘキサメチルジシラザン処理を施したシリコン基板上に均一に塗布し、１２０℃で９０秒間ホットプレート上で加熱、乾燥を行い、０．５０μｍのレジスト膜を形成した。このレジスト膜を、マスクを通してＡｒＦエキシマレーザー光で露光し、露光後直ぐに１１０℃で９０秒間ホットプレート上で加熱した。さらに２．３８重量％濃度のテトラメチルアンモニウムヒドロキシド水溶液で２３℃で６０秒間現像し、３０秒間純水にてリンスした後、乾燥した。このようにして得られたコンタクトホールパターンの形成されたサンプルを、ＫＬＡ２１１２機(ＫＬＡテンコール（株）製)により現像欠陥数を測定した(Threshold12、Pixcel Size＝０．３９）。
（２）現像欠陥数−II
上記（１）現像欠陥数−Ｉにおいて、露光しない以外は、加熱、現像、リンス、乾燥したサンプルについて同様に行い現像欠陥数を測定した。
【００９４】
【表１】

【００９５】
表１中の各記号は、下記の通りである。
ＰＡＧ−１：トリフェニルスルホニウムトリフレート
Ｎ−１：ヘキサメチレンテトラミン
Ｎ−２：１，５−ジアザビシクロ［４．３．０］−５−ノネン
Ｎ−３：１，８−ジアザビシクロ［５．４．０］−７−ウンデセン
Ｎ−４：１，４−ジアザビシクロ［２．２．２］オクタン
Ｗ−１：メガファックＦ１７６（大日本インキ（株）製）（フッ素系）
Ｗ−２：メガファックＲ０８（大日本インキ（株）製）（フッ素及びシリコーン系）
Ｗ−３：ポリシロキサンポリマーＫＰ−３４１（信越化学工業（株）製）（シリコーン系）
Ｗ−４：ポリオキシエチレンノニルフェニルエーテル
Ｓ−１：乳酸エチル
Ｓ−２：３−エトキシプロピオン酸エチル
Ｓ−３：γ−ブチロラクトン
Ｓ−４：プロピレンカーボネート
Ｓ−５：エチレンカーボネート
【００９６】
【表２】

【００９７】
表２の結果から明らかなように、本発明の感光性樹脂組成物は、いづれも現像欠陥が極めて少なかった。特に３種類の溶媒を用いた実施例３〜７は、現像欠陥がないか、あるいはあっても僅かであった。
一方、各比較例はいずれも現像欠陥が著しく多い。特に比較例４は、溶剤を乳酸エチルのみで構成した場合であり、現像欠陥数が実施例１と比べると倍以上多い。
比較例５は、界面活性剤として、本発明で特定されてたもの以外のものを用いた例であり、現像欠陥数が実施例１と比べると約倍近く多い。
【００９８】
【発明の効果】
本発明のポジ型感光性樹脂組成物は、レジスト性能、塗布性能、溶液の保存安定性、安全性に優れ、特に現像欠陥の問題を生じない点において優れる。従って、本発明のポジ型感光性樹脂組成物は、ＡｒＦエキシマレーザー光を露光光源とするリソグラフィーに特に有効である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a positive photosensitive resin composition used in a semiconductor manufacturing process such as an IC, a circuit board such as a liquid crystal or a thermal head, and other photofabrication processes. More specifically, the present invention relates to a positive photosensitive resin composition suitably used for fine processing of a semiconductor element using short-wavelength light energy rays such as deep ultraviolet rays, X-rays, and electron beams, and particularly a semiconductor using an ArF excimer laser. It is a positive photosensitive resin composition suitably used for microfabrication of an element.
[0002]
[Prior art]
In recent years, semiconductor integrated circuits have been highly integrated, LSIs and VLSIs have been put into practical use, and the minimum pattern width of integrated circuits has reached the sub-half micron region, and further miniaturization has progressed.
For this reason, the demand for a photolithography technique for forming a fine pattern is becoming stricter. As one of means for miniaturizing a pattern, it is known to shorten the wavelength of exposure light used for forming a resist pattern.
For example, in the production of a DRAM having a degree of integration up to 64 Mbits, i-line (365 nm) of a high-pressure mercury lamp has been used as a light source until now. In the mass production process of 256Mbit DRAM, KrF excimer laser (248nm) is put into practical use as an exposure light source instead of i-line, and light source with shorter wavelength is studied for the purpose of manufacturing DRAM with 1Gbit or higher integration. ArF excimer laser (19 3 nm), F ₂ The use of excimer laser (157 nm), X-rays, and electron beams is considered to be effective (Takumi Ueno, “Short Wavelength Photoresist Material-Microfabrication for ULSI”, Bunshin Publishing, 1988). .
[0003]
In particular, ArF excimer laser is positioned as the next-generation exposure technique, and development of a resist having high sensitivity, high resolution, and excellent dry etching resistance for ArF excimer laser exposure is desired.
As resist materials for conventional i-line and KrF excimer laser exposure, resists containing aromatic polymers are widely used in order to obtain high dry etching resistance. For example, novolak resin-based resists or polyvinylphenol-based chemicals are used. Amplified resists are known. However, since the aromatic ring introduced for the purpose of imparting dry etching resistance hardly transmits light in the wavelength range of ArF excimer laser light, it is difficult to expose to the bottom of the resist film. A pattern having a good cross-sectional shape could not be obtained.
[0004]
As one of the solutions to the problem of resist transparency, it is known to use an aliphatic polymer containing no aromatic ring, such as polymethyl methacrylate (J. Vac. Sci. Technol., B9, 3357 (1991)). However, such a polymer cannot be used because sufficient dry etching resistance cannot be expected. As described above, in developing a resist material for ArF excimer laser exposure, the greatest challenge is to achieve both improved transparency and high dry etching resistance.
Therefore, Proc. SPIE, 1672, 66 (1992) shows that a resist containing an alicyclic hydrocarbon group instead of an aromatic ring exhibits the same dry etching resistance as an aromatic group and has a small absorption at 193 nm. In recent years, the use of the polymer has been actively researched.
[0005]
Originally, attempts to apply a polymer containing an alicyclic hydrocarbon group to a resist have been made for a long time. For example, in JP-A-60-195542, JP-A-1-217453, and JP-A-2-59751, a norbornene-based polymer is used. Polymers are disclosed, and various alkali-soluble resins having a cycloaliphatic hydrocarbon skeleton and a maleic anhydride unit are disclosed in JP-A-2-146045.
Further, JP-A-5-80515 discloses a copolymer of norbornene and an acrylate ester protected with an acid-decomposable group. JP-A-4-39665, JP-A-5-265212, JP-A-5-80515. JP-A-7-234511 discloses a copolymer having an adamantane skeleton in the side chain, and JP-A-7-252324 and JP-A-9-221526 have 7 to 7 carbon atoms having a bridged cyclic hydrocarbon group. A compound in which 12 aliphatic cyclic hydrocarbon groups are linked to the side chain of the polymer, such as tricyclo [5.2.1.0. ^2,6 ] Decandimethylene group, tricyclo [5.2.1.0] ^2,6 Decanediyl group, norbornanediyl group, norbornanedimethyl group, adamantanediyl group are disclosed, and JP-A-7-199467 discloses tricyclodecanyl group, dicyclopentenyl group, dicyclopentenyloxyethyl group, norbornyl group Discloses compounds in which a cyclohexyl group is linked to a side chain of a polymer.
[0006]
Further, JP-A-9-325498 discloses polymers having cyclohexane and isobornyl skeletons in the main chain, and further JP-A-9-230595, JP-A-9-244247, JP-A-10-10739, WO97-33198, EP 794458 and EP 789278 disclose polymers in which various cyclic olefins such as dicycloolefin are introduced into the main chain, and JP-A-8-82925 and JP-A-9-230597 disclose menthyl of terpenoid skeletons. It is disclosed that compounds having a group or a menthyl derivative group are preferred.
[0007]
Further, a device has been devised to increase the resolving power by adding a low-molecular dissolution inhibitor.
JP-A-8-15865 discloses a dissolution inhibitor for t-butyl ester of androstane, and JP-A-9-265177 discloses an acid-decomposable group linked to a norbornyl group, an adamantyl group, a decanyl group, or a cyclohexyl group. Disclosed are low molecular weight dissolution inhibitors. Furthermore, Proc. SPIE 3049, 84, (1997) reports that adhesion and contrast can be improved by using a t-butyl ester oligomer of lithocholic acid as a dissolution inhibitor.
[0008]
Apart from the resist performance as described above, the generation of defects (voids) due to the lithography process has become one of the major causes of yield reduction, and has recently become a particularly important problem.
For example, it is said that development defects are generally caused by bubbles at the time of liquid accumulation and microbubbles caused by dissolved gas in the developer (Hirano et al .; ZW-9 (1996)), countermeasures against air bubbles are becoming more important as the wafer diameter increases and the developer discharge rate increases. As countermeasures against these bubbles, improvements have been made on the equipment that allows the developer to be discharged softly (see Science Forum, ULSI Manufacturing Contamination Control Technology, 41 (1992)) and the addition of a degassing mechanism for dissolved gas. Although attempts have been made to reduce bubbles, the level is not satisfactory.
In addition, in order to reduce development defects, nonionic surfactants are added to the developer to improve the wettability of the developer and promote bubble detachment, and surfactants in novolak resists. Attempts have been made to improve the affinity by optimizing the type and the amount added (Awashima et al .; 42nd JSAP lecture presentation 27p-ZW-7 (1996)).
However, these methods are not sufficient to reduce the development defects of chemically amplified resists for ArF using non-aromatic polymers. Rather, the development defects may be adversely affected. Until now, there was no guideline for improvement on how to deal with the reduction. Moreover, if the affinity of the resist is improved in order to reduce development defects, the remaining film rate and profile tend to deteriorate, making it difficult to achieve compatibility.
[0009]
In addition, conventional positive chemical amplification resists for KrF using aromatic polymers include, for example, Prooc.SPIE 1672,46, (1992), Prooc.SPIE 2438,551, (1995), Prooc.SPIE, 2438. , 563 (1995), Prooc.SPIE 1925,14, (1993), J.Photopolym.Sci.Tech.Vol.8.No.4,535 (1995), J.Photopolym.Sci.Tech.Vol.5.No. 1,207 (1992), J. Photopolym. Sci. Tech. Vol. 8, No. 4, 561 (1995), Jpn. J. Appl. Phys. 33, 7023 (1994), etc. As the standing time until (PEB) increases, the generated acid diffuses, or the acid on the resist surface is deactivated by basic impurities in the atmosphere. There was a problem that the profile and line width would change.
As means for solving these problems, techniques for adding an amine to a chemically amplified resist using an aromatic polymer are disclosed in JP-A 63-149640, JP-A 5-249662, and JP-A 5-127369. Kaihei 5-289322, JP-A-5-249683, JP-A-5-289340, JP-A-5-232706, JP-A-5-257282, JP-A-6-242605, JP-A-6-242606, JP-A-6-266100, JP-A-6-266110, JP-A-6-317902, JP-A-7-120929, JP-A-7-146558, JP-A-7-319163, JP-A-7-508840, JP-A-7-508840 JP-A-7-333844, JP-A-7-219217, JP-A-7-92678, JP-A-7-28247, JP-A-8-22120, JP-A-8-110638, Kaihei 8-123030, JP-A-9-274312, JP-A-9-166671, JP-A-9-292708, JP-A-9-325496, JP 7-508840, USP 5525453, USP 56 29134 , U.S. Pat. No. 5,667,938 and the like are well known.
However, when these amines are added to a chemically amplified resist for ArF using a non-aromatic polymer having a cycloaliphatic hydrocarbon skeleton structure, the sensitivity change is certainly the same as in the case of using an aromatic polymer. Although it is effective for resist pattern profile change and line width change after development, the development defect is extremely inferior, and countermeasures have been desired.
[0010]
Conventional naphthoquinone diazide / novolak resin-based positive photoresist coating solvents include glycol ethers, glycol ether esters such as 2-methoxyethanol and 2-ethoxyethanol, and acetates thereof, such as ethylene glycol monomethyl. Ether acetate, ethylene glycol monoethyl ether acetate and the like have been used in general.
[0011]
However, since it was pointed out that the solvent containing these glycol ether derivatives had adverse effects on the reproductive function of mice in 1979, animal experiments were repeated mainly in Europe and the United States. Confirmed and reported as a potential biological threat to worker safety.
(NIOH Current Intelligence Bulletin, Vol. 39, No. 5, 1983) The US Environmental Protection Agency (EPA) recommended that regulations be tightened in 1984, and the movement for tightening regulations spread.
[0012]
In response to this fact, it has been desired for many photoresist manufacturers to develop a photoresist product of a low toxicity solvent that does not contain ethylene glycol ethers.
As an alternative low-toxic solvent, monooxycarboxylic acid esters such as ethyl lactate, methyl 3-methoxypropionate, methyl 3-ethoxypropionate and ethyl 3-ethoxypropionate (Japanese Patent Publication No. 3-22619, US Pat. No. 5,238,774, EP21667) And propylene glycol monomethyl ether acetate (Japanese Patent Publication No. 3-1659, US619468). Other than this, cyclopentanone N-hexanol, diethylene glycol dimethyl ether (SEMICONDUCTOR INTERNATIONAL, Vol. 4, pp132-133, 1988), 2-heptanone (NIKKEI MATERIALS & TECHNOLOGY Vol. 12, p83-89, 1993), A naphthoquinonediazide / novolak resin-based positive photoresist composition using a solvent such as ethyl pyruvate (Japanese Patent Laid-Open No. 63-220139, Japanese Patent Laid-Open No. 4-36752, US5100758) has been proposed.
[0013]
Similarly, as a solvent for a resist composition for i-line exposure or a positive chemically amplified resist composition for KrF exposure, a combination of the above methyl 3-methoxypropionate and ethyl 3-ethoxypropionate, No.), a combination of ethyl lactate and ethyl 3-ethoxypropionate (JP-A-6-308734) and the like.
Thus, although many alternative solvents have been proposed so far, toxicity tests (chronic toxicity, reproductive toxicity, teratogenicity, mutagenicity, carcinogenicity, tests on life form fate, etc.) have been conducted for a long time. All of these are not necessarily proven to be safe.
[0014]
In the first place, ethylene glycol monoethyl ether acetate is toxic because it is decomposed into 2-ethoxyethanol by biological metabolism to ethoxyacetic acid, which is considered to be the cause of toxicity (teratogenicity).
However, for example, ethyl lactate is considered to be safe because it decomposes into lactic acid and ethanol by biological metabolism, and is also recognized as a food additive. Ethyl-3-ethoxypropionate is converted to 3-ethoxypropionic acid, ethylmalonic acid, and malonic acid by biometabolism, and, like ethyl lactate, alkoxyacetic acid is not produced and is considered to be highly stable. . Similarly, propylene glycol monomethyl ether acetate is also converted to propylene glycol, and no alkoxyacetic acid is produced, which has been confirmed to be much less toxic than the corresponding ethylene glycols. One of the requirements to be satisfied by the photoresist solvent is the low toxicity.
[0015]
The next important requirement to be met is applicability.
In recent years, with the high integration of LSI, the wafer diameter has been increased. As the diameter becomes larger, there is a problem that the uniformity of spin coating in the wafer surface is deteriorated or unpainted residue is generated, and the industrial value is reduced.
[0016]
With regard to a naphthoquinone diazide / novolak resin-based positive photoresist composition, for the purpose of improving the coating property, JP-A-58-105143, 58-203434, and 62-36657 disclose a known resist composition. Solvents for ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, N, N-dimethylformamide, dioxane, cyclohexanone, cyclopentanone, γ-butyllactone, lactic acid It is described that a fluorine-based surfactant is added to ethyl and methyl lactate, and US Pat. No. 4,526,856 and JP-A No. 59-231534 disclose cyclopentanone and cyclohexane and a carbon number of 5 to 1. It is described that combine the aliphatic alcohol.
[0017]
Further, JP-A-60-24545 discloses a striation (generated when a resist composition is applied on a substrate) by combining a solvent having a boiling point of 60 to 170 ° C. with a solvent having a boiling point of 180 to 350 ° C. It has been disclosed to improve coating unevenness. The cause of striation is that the temperature difference between the liquid surface and the interior caused by the rapid evaporation of the solvent causes natural convection in the liquid film. A technique for preventing striation by adding a surfactant as described above or a mixed solvent is being established.
[0018]
However, even if striations can be prevented by the above method or the like, the uniformity of coating in the radial direction of the substrate (non-uniform film thickness) often becomes a problem. For example, it has been pointed out that when an ethyl lactate solvent resist is applied, the variation in film thickness becomes larger than that of an ethylene glycol monoethyl ether acetate solvent (NIKKEI MATERIALS & TECHNOLOGY Vol. 12, p87, 1993).
[0019]
It has been reported that the coating property in such a resist composition for i-line or KrF exposure is related to physical properties such as the evaporation rate of solvent and latent heat of vaporization (Monthly Semiconductor World, Vol. 1, p125-128). In order to solve this problem, ethyl lactate and ethyl 3-ethoxypropionate may be mixed (Japanese Patent Laid-Open No. 3-504422, US-5063138, EP 442952, WO90 / 05325), Many contrivances have been made so far, such as mixing of isoamyl acetate or n-amyl acetate (US Pat. No. 5,335,583, EP 510670, JP-A-5-34918), mixing of ethyl lactate, anisole and amyl acetate (US Pat. No. 5,128,230).
[0020]
Similar to or more than the naphthoquinone diazide / novolak resin-based positive photoresist composition, the positive chemically amplified resist composition is required to have uniformity within the wafer surface. That is, in the positive chemical amplification resist composition, in most cases, a large-diameter wafer (6 inches or more) is used for manufacturing a semiconductor.
[0021]
This coatability can be improved to some extent by optimizing the conditions of the coating apparatus, that is, the coating atmosphere temperature, the substrate temperature, the coating resist temperature, the exhaust, etc. Most preferably, a uniform coatability is obtained. Apart from the above problems, for example, after filtering the positive chemically amplified resist composition with a microfilter, if left standing, fine particles that cannot be visually observed are deposited, and the resist composition on which the fine particles have been deposited is kept for a longer period of time. Storage may eventually lead to precipitation.
[0022]
When a resist pattern is formed on a wafer using a resist composition containing such fine particles, there is a problem that the fine particles remain in a portion where the resist is to be removed by development and resolution is lowered.
These fine particles are mainly a photoacid generator, an acid-decomposable dissolution inhibitor, an alkali-soluble resin having an acid-decomposable group, and the like in a positive chemically amplified resist composition.
[0023]
For the purpose of improving the stability over time, mixing with a high boiling point solvent such as N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethylformamide will certainly improve the stability over time, but the resolution and adhesion of the resist. The characteristics such as heat resistance will deteriorate.
Thus, the third requirement of the positive photoresist solvent is that the resist components do not precipitate over time and the storage stability is good.
[0024]
Furthermore, if the photoacid generator or the acid-decomposable dissolution inhibitor decomposes during storage, there is a risk that the sensitivity will change or the photoresist container (glass bottle) will break due to internal pressure. Therefore, a solvent that does not decompose the photoacid generator or the acid-decomposable dissolution inhibitor is preferable.
Other requirements to be satisfied include a low hygroscopic property of the solvent and monthly Semiconductor World Vol. 1, p125-128, 1991, a solvent that does not deteriorate the characteristics (sensitivity, resolution, profile, scum, adhesion, heat resistance) of the resist is preferable. For example, as described in JP-A-5-173329, ethyl lactate and the like are likely to absorb moisture during a photoresist preparation process and a coating process. A photoresist that has absorbed moisture degrades the properties of the resist.
[0025]
Further, it is known that if the residual resist solvent after baking is large, the resist pattern is likely to be thermally deformed (heat resistance is deteriorated).
Furthermore, when a novolak resin is used as a binder, it is known that the absorption in the deep UV region (248 nm) varies greatly depending on the type of the solvent (SPIE Vol. 1262, p180-187). 1990)) Solvents with low absorption in the Deep UV region are preferred. In the positive chemical amplification resist composition, the residual solvent in the resist film greatly affects the acid diffusion (for example, J. Vac. Sci. Technol. B, Vol. 9, No. 2, 278-289).
(1991)), acid diffusion is caused by the resolution and the delay time effect between exposure and post-heating (PEB) (the phenomenon that resist pattern shape deterioration and line width change occur when the exposure time from exposure to PEB increases. ) Etc. The acid diffusivity can naturally vary depending on the resist composing compound such as a photoacid generator or an acid-decomposable dissolution inhibitor, but it varies greatly depending on the type of solvent. Therefore, the choice of solvent is a chemically amplified resist composition. Then it becomes particularly important.
[0026]
In addition, in a chemically amplified resist using a polymer having an alicyclic hydrocarbon skeleton, the development defects are extremely likely to occur compared to conventional novolak resin resists and polyhydroxystyrene resists having an aromatic ring. Become. This is presumably because the polymer becomes hydrophobic and the penetration of the developer into the resist film becomes non-uniform. Therefore, as for the resist solvent, it is important to select a solvent that does not cause development defects, but there has been no report that should serve as a guideline.
[0027]
As described above, the coating performance, the storage stability of the solution, and the resist performance are attributes related to the constituent components such as the binder polymer and the photoacid generator, and at the same time, are characteristics that are greatly affected by the solvent. It has been known. However, the resist solvent must satisfy all the requirements of coating performance, solution storage stability, safety, resist performance, and development defects at the same time, but a polymer having an alicyclic hydrocarbon skeleton is required. In the chemically amplified resist used, what has been hardly known so far is the actual situation.
[0028]
[Problems to be solved by the present invention]
An object of the present invention is to provide a chemically amplified resist composition using a polymer having an alicyclic hydrocarbon skeleton, which is useful for deep ultraviolet light, particularly ArF excimer laser light lithography. An object of the present invention is to provide a positive photosensitive resin composition which is excellent in storage stability and safety of a solution and does not cause a problem of development defects.
[0029]
[Means for Solving the Problems]
As a result of intensive studies on the constituent materials of the positive chemically amplified resist composition, the present inventors have found that a polymer containing an alicyclic hydrocarbon skeleton structural unit, a photoacid generator, a nitrogen-containing basic compound, a fluorine-based polymer, Knowing that the above object can be achieved by combining a silicon surfactant and a specific solvent, the present invention has been achieved.
That is, this invention is invention of the following structure, The said objective is achieved by this.
(1) (A) a polymer having a cyclic aliphatic hydrocarbon skeleton, which is decomposed by the action of an acid and becomes alkali-soluble,
(B) a compound that generates an acid by actinic rays,
(C) a nitrogen-containing basic compound,
(D) a fluorine-based and / or silicon-based surfactant, and
(E) (a) containing 60 to 90% by weight of ethyl lactate based on the total solvent, and
(B) A solvent containing 10 to 40% by weight of ethyl 3-ethoxypropionate based on the total solvent
A positive-type photosensitive resin composition comprising:
[0030]
(2) (E) The solvent further comprises (c) a solvent having a boiling point of 180 ° C. or more and a solubility parameter of 12 or more, based on the total amount of the solvent (1). The positive photosensitive resin composition as described.
(3) The positive photosensitive resin composition as described in (2) above, wherein the solvent (c) is at least one selected from γ-butyrolactone, ethylene carbonate, and propylene carbonate.
(4) (A) The number of carbon atoms forming the cycloaliphatic hydrocarbon skeleton of the polymer that has a cycloaliphatic hydrocarbon skeleton and decomposes by the action of an acid to become alkali-soluble is 5-25. The positive photosensitive resin composition as described in any one of (1) to (3) above.
[0031]
(5) Any of the above (1) to (4), wherein the nitrogen-containing basic compound (C) is at least one selected from organic amines, basic ammonium salts, and basic sulfonium salts. A positive photosensitive resin composition according to claim 1.
(6) It has a molecular weight of 2000 or less, has a group that can be decomposed by the action of an acid, and further contains a low-molecular acid-decomposable dissolution inhibitor compound whose alkali solubility is increased by the action of an acid. The positive photosensitive composition according to any one of (1) to (5).
(7) The positive photosensitive resin composition as described in any one of (1) to (6) above, wherein the actinic ray is far ultraviolet light having a wavelength of 220 nm or less.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the compounds used in the present invention will be described in detail.
First, as the polymer (A) having a cycloaliphatic hydrocarbon skeleton structure in the present invention that becomes alkali-soluble by the action of an acid, a conventionally known polymer can be used.
The number of carbon atoms for forming the hydrocarbon skeleton ring of the alicyclic moiety is preferably 5 to 25, and specific examples thereof are shown below.
[0033]
[Chemical 1]

[0034]
[Chemical 2]

[0035]
[Chemical 3]

[0036]
Specific examples of the polymer include cyclic aliphatic hydrocarbon skeleton structures such as structural units represented by the following (a-1) to (a-15) and (b-1) to (b-7). Can be mentioned. Moreover, the (A) polymer concerning this invention may contain the structural unit represented by following (c-1)-(c-4) as a copolymerization component.
[0037]
[Formula 4]

[0038]
[Chemical formula 5]

[0039]
[Chemical 6]

[0040]
In the structural units represented by (a-1) to (a-15) and (b-1) to (b-7), A and B are each independently a hydrogen atom, a hydroxyl group, a carboxyl group, or an alkoxy group. A carbonyl group, a substituted or unsubstituted alkyl group, alkoxy group or alkenyl group having 1 to 10 carbon atoms, and A and B may be bonded to form a ring. X and Y each independently represent a group that decomposes by the action of an acid.
In the formulas (b-1) to (b-7) and (c-1) to (c-4), R represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms such as a methyl group. Z represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, an alkoxycarbonyl group or a group capable of decomposing by the action of an acid. )
[0041]
In the above, examples of the alkoxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, and a butoxycarbonyl group.
Examples of the alkyl group having 1 to 10 carbon atoms include a linear, branched or cyclic alkyl group which may be substituted. Specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, n -Butyl group, t-butyl group, cyclopentyl group, cyclohexyl group, hydroxymethyl group, hydroxyethyl group and the like can be mentioned.
Examples of the alkoxy group having 1 to 10 carbon atoms include a methoxy group, an ethoxy group, an n-butoxy group, a t-butoxy group, a propoxy group, and an isopropoxy group. Examples of the alkenyl group having 2 to 10 carbon atoms include allyl group, vinyl group, and 2-propenyl group.
The ring formed by combining A and B includes A and B
-C (= O) -OC (= O)-,
-C (= O) -NH-C (= O)-,
-CH ₂ -C (= O) -OC (= O)-,
Etc. to form a ring.
[0042]
As the group capable of decomposing by the action of an acid, — (CH ₂ ) _n -COORa group or-(CH ₂ ) _n -OCORb group. Here, Ra represents a hydrocarbon group having 2 to 20 carbon atoms, and examples of the hydrocarbon group include a t-butyl group, a norbornyl group, and a cyclodecanyl group. Rb represents a tetrahydrofuranyl group, a tetrahydropyranyl group, an alkoxyethyl group such as an ethoxyethyl group or an isopropylethyl group, a lactone group, or a cyclohexyloxyethyl group. n represents 0 or 1.
[0043]
Examples of the further substituent in each of the above groups include a halogen atom, a cyano group, and a nitro group.
[0044]
The polymer (A) comprising the structural units represented by the above formulas (a-1) to (a-6) is, for example, ring-opening a cyclic olefin in an organic solvent or a non-organic solvent in the presence of a metathesis catalyst. Obtained by polymerization and subsequent hydrogenation. Ring-opening (co) polymerization is described in, for example, WL Truett et al .; J. Am. Chem. Soc., 82, 2337 (1960), A. Pacreau; Macromol. Chem., 188, 2585 (1987), JP-A 51-31800. No. 1, JP-A-1-197460, JP-A-2-42094, EP-0789278, and the like. Examples of the metathesis catalyst used here include compounds described in the Society of Polymer Science, Japan: Synthesis and Reaction of Polymers (1), Kyoritsu Shuppan p375-381 (1992), JP-A-49-77999, specifically, Can include a halogenated compound of a transition metal such as tungsten and / or molybdenum and an organoaluminum compound or a catalyst system comprising these and a third component.
[0045]
Specific examples of the tungsten and molybdenum compounds include molybdenum pentachloride, tungsten hexachloride and tungsten oxytetrachloride. Examples of the organoaluminum compounds include triethylaluminum, triisobutylaluminum, trihexylaluminum, diethylaluminum monochloride, -N-butylaluminum monochloride, ethylaluminum sesquichloride, diethylaluminum monobutoxide and triethylaluminum-water (molar ratio 1: 0.5). In carrying out the ring-opening polymerization, the use ratio of the organoaluminum compound to 1 mol of the tungsten or molybdenum compound is preferably 0.5 mol or more.
As the third component for improving the polymerization activity of the catalyst, water, hydrogen peroxide, oxygen-containing organic compound, nitrogen-containing organic compound, halogen-containing organic compound, phosphorus-containing organic compound, sulfur-containing organic compound, metal-containing organic Compounds, and are used together at a ratio of 5 mol or less per 1 mol of tungsten or molybdenum compound. The catalyst is used in a proportion of 0.1 to 20 mol with respect to 100 mol of the monomer, although the proportion of the catalyst with respect to the monomer depends on the kind thereof.
[0046]
The polymerization temperature in the ring-opening (co) polymerization is preferably −40 ° C. to + 150 ° C., and is desirably performed in an inert gas atmosphere. Solvents used include aliphatic hydrocarbons such as pentane, hexane, heptane and octane; alicyclic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as benzene, toluene and xylene; methylene chloride, 1, Halogenated hydrocarbons such as 1-dichloroethane, 1,2-dichloroethylene, 1-chloropropane, 1-chlorobutane, 1-chloropentane, chlorobenzene, bromobenzene, o-dichlorobenzene, m-dichlorobenzene; diethyl ether, tetrahydrofuran, etc. Examples include ether compounds.
[0047]
The polymer (A) used in the present invention is obtained by hydrogenating the polymer obtained by such ring-opening (co) polymerization. The catalyst used in the hydrogenation reaction may be a heterogeneous catalyst or a homogeneous catalyst used in the usual hydrogenation reaction of olefinic compounds.
Examples of the heterogeneous catalyst include a solid catalyst in which a noble metal catalyst such as palladium, platinum, nickel, ruthenium, or rhodium is supported on a carrier such as carbon, silica, alumina, or titania. Examples of homogeneous catalysts include nickel naphthenate / triethylaluminum, nickel acetylacetonate / triethylaluminum, cobalt octenoate / n-butyllithium, titanocene dichloride / diethylaluminum monochloride, rhodium acetate, chlorotris (triphenylphosphine) rhodium, etc. The rhodium catalyst can be mentioned.
Among these catalysts, the heterogeneous catalyst is advantageous because it has high reaction activity, is easy to remove after the reaction, and the resulting polymer is not colored.
[0048]
The hydrogenation reaction can be performed at 0 to 200 ° C., preferably 20 to 180 ° C. in a hydrogen gas atmosphere of normal pressure to 300 atm, preferably 3 to 200 atm. The hydrogenation rate is usually 50% or more, preferably 70% or more, and more preferably 80% or more. When the hydrogenation rate is less than 50%, the thermal stability and temporal stability of the resist are deteriorated.
[0049]
The polymer composed of the structural units represented by the above formulas (a-7) to (a-15) is, for example, radical (co) polymerization of a cyclic aliphatic hydrocarbon monomer in the presence of an effective amount of a free radical polymerization initiator. Can be synthesized. Specifically, J. Macromol. Sci. Chem. A-5 (3) 491 (1971), A-5 (8) 1339 (1971), Polym. Lett. Vol. 2,469 (1964), USP 3143533, It can be synthesized by the methods described in US Pat. No. 3,261,815, US Pat. No. 3,510,461, US Pat. No. 3,793,501, US Pat. No. 3,703,501, and JP-A-2-14645.
Preferable initiators used for radical (co) polymerization include 2,2′-azobis (2-methylpropanenitrile), benzoyl peroxide, dicumyl peroxide and the like. The concentration of the initiator is usually 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on the total weight of the monomers. The polymerization temperature can be varied over a wide range, and the polymerization is usually carried out in the range of room temperature to 250 ° C, preferably in the range of 40 to 200 ° C, more preferably in the range of 60 to 160 ° C.
[0050]
The polymerization or copolymerization is preferably performed in an organic solvent. A solvent that dissolves the monomer at a predetermined temperature and also dissolves the produced polymer is preferable. The preferred solvent varies depending on the type of monomer to be copolymerized, and examples thereof include aromatic hydrocarbons such as toluene; aliphatics such as ethyl acetate; aromatic esters; and aliphatic ethers such as tetrahydrofuran. Can do.
After the reaction for a predetermined time, it is preferable to perform distillation under reduced pressure and purification for the purpose of separating the obtained polymer from unreacted monomer components, solvents and the like.
[0051]
Polymers having the structural units (b-1) to (b-7) or those containing the copolymer components (c-1) to (c-4) are free radicals in the presence of an effective amount of a free radical initiator. It can be synthesized by (co) polymerization.
In the polymer (A), the content of the structural unit having a cycloaliphatic skeleton is preferably 10 mol% or more, more preferably 20 mol% or more, and further preferably 30 mol% or more of the total structural units.
In the polymer (A), the content of the structural unit having an acid-decomposable group is 10 to 90 mol%, preferably 15 to 85 mol%, more preferably 20 to 80 mol%, based on all structural units. It is.
Moreover, in the polymer used for this invention, content of other copolymerization components, such as a unit represented by (c-1)-(c-4), is 3-60 mol in the repeating unit of all the monomers. % Is preferable, more preferably 5 to 55 mol%, still more preferably 10 to 50 mol%.
[0052]
The polymer (A) preferably has a weight average molecular weight in the range of 1500 to 100,000, more preferably in the range of 2000 to 70000, and particularly preferably in the range of 3000 to 50000. If the molecular weight is less than 1500, dry etching resistance, heat resistance, and adhesion to the substrate are insufficient, and if the molecular weight exceeds 100,000, the resist sensitivity is lowered, which is not preferable. The molecular weight distribution (Mw / Mn) is preferably 1.0 to 6.0, more preferably 1.0 to 4.0. The smaller the molecular weight distribution, the better the heat resistance and image performance (resist profile, defocus latitude, etc.). It becomes.
The weight average molecular weight and molecular weight distribution (Mw / Mn) of the polymerization (A) are measured as polystyrene equivalent values by gel permeation chromatography equipped with a refractive index detector.
[0053]
In the positive photosensitive resin composition of the present invention, the content of the polymer (A) is 50 to 99.7% by weight, preferably 70 to 99% by weight, in terms of solid content.
The positive photosensitive resin composition of the present invention can contain other polymers as required in addition to the polymer (A). The content of the other polymer is preferably 30 parts by weight or less, more preferably 20 parts by weight or less, and particularly preferably 10 parts by weight or less per 100 parts by weight of the polymer (A).
[0054]
As said other polymer which the positive photosensitive resin composition of this invention can contain, what is compatible with the alicyclic polymer of this invention should just be sufficient, poly p-hydroxyethylene, hydrogenated poly p-- Hydroxyethylene, novolac resin and the like can be mentioned.
[0055]
Next, (B) a compound (hereinafter also referred to as “(B) photoacid generator”) that decomposes upon irradiation with actinic light and generates an acid contained in the positive photosensitive resin composition of the present invention will be described. To do.
Examples of the photoacid generator (B) used in the present invention include a photoinitiator for photocationic polymerization, a photoinitiator for photoradical polymerization, a photodecolorant for dyes, a photochromic agent, or ultraviolet light, A well-known photoacid generator and a mixture thereof are appropriately selected and used for micro-photoresist that generates acid by ultraviolet rays, KrF excimer laser light, ArF excimer laser light, electron beam, X-ray, molecular beam, ion beam, etc. can do.
In the present invention, actinic rays are used in a broad concept including radiation as described above.
[0056]
(B) The photoacid generator is not particularly limited as long as it dissolves in the organic solvent described later used in the positive photosensitive resin composition of the present invention, but generates a photoacid that generates an acid with light of 220 nm or less. It is preferable that it is an agent. Moreover, it may be used alone or in combination of two or more kinds, and may be used in combination with an appropriate sensitizer.
[0057]
Examples of usable photoacid generator (B) include triphenylsulfonium salt derivatives described in J. Org. Chem. Vol. 43, N0.15, 3055 (1978) and Japanese Patent Application No. 9-279071. Other onium salts (sulfonium salts, iodonium salts, phosphonium salts, diazonium salts, ammonium salts) described in 1) can also be used.
Specific examples of onium salts include diphenyliodonium triflate, diphenyliodonium pyrenesulfonate, diphenyliodonium dodecylbenzenesulfonate, triphenylsulfonium triflate, triphenylsulfonium hexafluoroantimonate, diphenyliodonium hexafluoroantimonate, triphenylsulfonium naphthalenesulfonate , Triphenylsulfonium camphorsulfonium, (4-methoxyphenyl) phenyliodonium trifluoromethanesulfonate, bis (t-butylphenyl) iodonium trifluoromethanesulfonate, and the like.
[0058]
Further, disclosed in JP-A-3-103854, JP-A-3-103856, and JP-A-4-121960, diazodisulfones and diazoketosulfones, JP-A 64-18143, and JP-A-2-245756. And the disulfones described in JP-A-2-71270 can also be suitably used. Further, US Pat. No. 3,849,137, JP-A 63-26653, JP-A 62-69263, JP-A 63-146038, JP-A 63-163452, JP-A 62-153853, JP-A 63-63. A compound in which a group capable of generating an acid by light described in No. 146029 or the like is introduced into the main chain or side chain of a polymer can also be used, and Japanese Patent Laid-Open Nos. 7-25846, 7-28237, and 7-92675, JP-A-8-27120, aliphatic alkylsulfonium salts having a 2-oxocyclohexyl group, and N-hydroxysuccinimide sulfonates, as well as J. Photopolym. Sci., Tech., Vol. 7, The sulfonium salts described in No. 3,423 (1994) can also be suitably used, and they can be used alone or in combination of two or more.
[0059]
The content of these (B) compounds that decompose upon irradiation with actinic rays to generate an acid is usually 0.001 to 40% by weight, preferably based on the total weight (solid content) of the photosensitive resin composition, It is 0.01 to 20 weight%, More preferably, it is 0.1 to 5 weight%. (B) If the amount of the photoacid generator is less than 0.001% by weight, the sensitivity will be low, and if it is more than 40% by weight, the light absorption of the resist will be too high, resulting in profile deterioration and process margins, especially bake margins. It is not preferable.
[0060]
Next, the (C) nitrogen-containing basic compound contained in the positive photosensitive resin composition of the present invention will be described. (C) As the nitrogen-containing basic compound, an organic amine, a basic ammonium salt, or a basic sulfonium salt is preferably used because it has excellent sensitivity, resolution, and profile, but does not deteriorate sublimation or resist performance. I just need it.
For example, Japanese Patent Laid-Open Nos. 63-149640, 5-24962, 5-127369, 5-289322, 5-249683, 5-289340, and 5-232706. JP-A-5-257282, JP-A-6-242605, JP-A-6-242606, JP-A-6-266100, JP-A-6-266110, JP-A-6-317902, JP-A-7-120929, JP-A-7-146558, JP-A-7-319163, JP-A-7-508840, JP-A-7-333844, JP-A-7-219217, JP-A-7-92678, JP-A-7-28247, Special Kaihei 8-22120, JP-A-8-110638, JP-A-8-123030, JP-A-9-274312, JP-A-9-16 871 No., JP-A-9-292708, JP-A-9-325496, Hei No. 7-508840, No. USP5525453, JP USP5629134, it is possible to use a basic compound as described in such Patent USP5667938.
[0061]
Particularly preferably, 1,5-diazabicyclo [4.3.0] -5-nonene, 1,8-diazabicyclo [5.4.0] -7-undecene, 1,4-diazabicyclo [2.2.2]. Octane, 4-dimethylaminopyridine, 1-naphthylamine, piperidine, hexamethylenetetramine, imidazoles, hydroxypyridines, pyridines, 4,4'-diaminodiphenyl ether, pyridinium p-toluenesulfonate, 2,4,6-trimethyl Examples thereof include pyridinium p-toluenesulfonate, tetramethylammonium p-toluenesulfonate, and tetrabutylammonium lactate.
(C) A basic compound can be used individually by 1 type or in combination of 2 or more types.
[0062]
(C) Content of a nitrogen-containing basic compound is 0.001-10 weight part normally with respect to 100 weight part of photosensitive resin compositions (solid content), Preferably it is 0.01-5 weight part. If it is less than 0.001 part by weight, the effect cannot be sufficiently obtained. On the other hand, when the amount exceeds 10 parts by weight, the sensitivity is lowered and the developability of the non-exposed part tends to be remarkably deteriorated.
[0063]
Next, the (D) fluorine-based and / or silicon-based surfactant contained in the positive photosensitive resin composition of the present invention will be described.
The photosensitive resin composition of the present invention can contain a fluorine-based surfactant, a silicon-based surfactant, a surfactant having both fluorine atoms and silicon atoms, or a mixture of two or more thereof. .
Examples of these (D) surfactants include, for example, JP-A-62-36663, JP-A-61-226746, JP-A-61-226745, JP-A-62-170950, JP-A-63-34540. , JP-A-7-230165, JP-A-8-62834, JP-A-9-54432, JP-A-9-5988, and the following commercially available surfactants may be used as they are. it can.
Examples of commercially available surfactants that can be used include F-top EF301 and EF303 (manufactured by Shin-Akita Kasei Co., Ltd.), Florard FC430 and 431 (manufactured by Sumitomo 3M Co., Ltd.), MegaFuck F171, F173, F176 and F189 , R08 (Dainippon Ink Co., Ltd.), Surflon S-382, SC101, 102, 103, 104, 105, 106 (Asahi Glass Co., Ltd.), etc. be able to. Polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical Co., Ltd.) can also be used as a silicon surfactant.
Of these surfactants, surfactants having both fluorine atoms and silicon atoms are particularly excellent in improving development defects.
[0064]
(D) The compounding quantity of surfactant is 0.01 weight part-2 weight part normally per 100 weight part of solid content in the composition of this invention, Preferably it is 0.01 weight part-1 weight part.
These surfactants can be used alone or in combination of two or more.
[0065]
The positive photosensitive resin composition of the present invention has a molecular weight of 2000 or less as necessary, a group having a group that can be decomposed by the action of an acid, and an alkali solubility that is increased by the action of an acid. Degradable compounds can be included.
For example, Proc. SPIE, 2724, 355 (1996), JP-A-8-15865, USP531 0619, USP-5372921, J. Photopolym. Sci., Tech., Vol. 10, No. 3, 511 (1997)). Contains alicyclic compounds and acid-decomposable groups such as cholic acid derivatives, dehydrocholic acid derivatives, deoxycholic acid derivatives, lithocholic acid derivatives, ursocholic acid derivatives and abietic acid derivatives containing the described acid-decomposable groups Aromatic compounds such as naphthalene derivatives can be used as the low-molecular acid-decomposable compound.
Furthermore, the low-molecular acid-decomposable dissolution inhibiting compound described in JP-A-6-51519 can also be used in an addition range at a level that does not deteriorate the 220 nm permeability, and a 1,2-naphthoquinonediazite compound can also be used. .
When the low molecular acid decomposable dissolution inhibiting compound is used in the photosensitive resin composition of the present invention, the content thereof is usually 1 to 50% by weight based on the total weight (solid content) of the photosensitive resin composition. It is used in a range, preferably 3 to 40% by weight, more preferably 5 to 30% by weight.
Addition of these low molecular acid decomposable dissolution inhibiting compounds not only further improves the development defects, but also improves dry etching resistance.
[0066]
Next, the (E) solvent used in the present invention will be described.
The (E) solvent used in the present invention contains (a) ethyl lactate and (b) ethyl 3-ethoxypropionate. The main solvent (a) ethyl lactate is used in the range of 60 to 90% by weight, preferably 60 to 85% by weight, more preferably 65 to 80% by weight in the solvent (E).
(A) (b) Ethyl 3-ethoxypropionate, which is a solvent used in combination with ethyl lactate, is used in the range of 10 to 40% by weight in the solvent, preferably in the range of 10 to 30% by weight, more preferably It is used in the range of 10 to 25% by weight.
The total of (a) ethyl lactate and (b) ethyl 3-ethoxypropionate preferably accounts for 70% by weight or more in the solvent (E), and if it is less than 70% by weight, the object of the present invention may not be sufficiently achieved. is there.
[0067]
In the present invention, the solvent other than the above (a) and (b) has a boiling point (bp) of 180 ° C. or higher, preferably 185 ° C. or higher, and a solubility parameter (SP value) of 12. As described above, it is preferable that the solvent (c) in the range of 12.4 or more is contained in the solvent (E) in an amount of 1 to 20% by weight, preferably 3 to 15% by weight.
By using such a solvent (c) together, development defects are dramatically improved. However, mixing in an amount exceeding 20% by weight is not preferable because the adhesion to the substrate deteriorates.
Specific examples of the solvent (c) include γ-butyrolactone (bp = 190 ° C., SP value = 12.6), propylene carbonate (bp = 242 ° C., SP value = 13.3). ), Ethylene carbonate (bp = 239 ° C., SP value = 14.7), N, N-dimethylimidazolinone (bp = 200 ° C., SP value = 12.4), dimethyl sulfoxide ( b.p. = 189 ° C., SP value = 13.0) and the like. Among these, γ-butyrolactone, propylene carbonate, and ethylene carbonate are particularly preferable for achieving the effects of the present invention.
These (c) solvents can be used singly or in combination of two or more.
[0068]
The above solvent is preferably used as the solvent (E) of the present invention, but other solvents can be further contained in an amount not exceeding the effects of the present invention, preferably in an amount of 5% by weight or less.
Other solvents that can be used include cyclohexanone, 2-heptanone, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether propionate, propylene glycol monoethyl ether acetate, methyl 3-methoxypropionate, β-methoxyiso Examples include methyl butyrate, ethyl butyrate, propyl butyrate, methyl isobutyl ketone, ethyl acetate, isoamyl acetate, diacetone alcohol, and N-methylpyrrolidone.
[0069]
In the positive photosensitive resin composition of the present invention, if necessary, further a dissolution accelerating compound for a developer, an antihalation agent, a plasticizer, a surfactant, a photosensitizer, an adhesion assistant, a crosslinking agent, A photobase generator and the like can be contained.
[0070]
Examples of the dissolution promoting compound that can be used in the present invention include compounds containing two or more phenolic hydroxyl groups described in JP-A-3-206458, one naphthol such as 1-naphthol, or one carboxyl group. Examples thereof include low molecular compounds having a molecular weight of 1000 or less, such as compounds having the above, carboxylic acid anhydrides, sulfonamide compounds and sulfonylimide compounds.
The blending amount of these dissolution promoting compounds is preferably 30% by weight or less, more preferably 20% by weight or less, based on the total weight (solid content) of the composition.
[0071]
As a suitable antihalation agent, a compound that efficiently absorbs irradiated radiation is preferable, and substituted benzenes such as fluorene, 9-fluorenone, and benzophenone; anthracene, anthracene-9-methanol, anthracene-9-carboxyethyl, phenanthrene , Polycyclic aromatic compounds such as perylene and azylene. Of these, polycyclic aromatic compounds are particularly preferred. These antihalation agents exhibit the effect of improving standing waves by reducing the reflected light from the substrate and reducing the influence of multiple reflection in the resist film.
[0072]
A nonionic surfactant can be used in combination for the purpose of improving the coating property of the photosensitive resin composition of the present invention or improving developability.
Nonionic surfactants that can be used in combination include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyethylene glycol dilaurate, polyethylene glycol distearate, polyoxyethylene sorbitan mono Examples include stearate and sorbitan monolaurate.
[0073]
Moreover, in order to improve the acid generation rate by exposure, a photosensitizer can be added. Suitable photosensitizers include benzophenone, p, p′-tetramethyldiaminobenzophenone, 2-chlorothioxanthone, anthrone, 9-ethoxyanthracene, pyrene, phenothiazine, benzyl, benzoflavine, acetophenone, phenanthrene, benzoquinone, anthraquinone, 1 , 2-naphthoquinone and the like, but are not limited thereto. These photosensitizers can also be used as the antihalation agent.
[0074]
Furthermore, in the photosensitive resin composition of the present invention, it is preferable to reduce metal impurities such as metal and impurity components such as chloro ions to 100 ppb or less. The presence of a large amount of these impurities is not preferable because it causes malfunctions, defects, and a decrease in yield in manufacturing a semiconductor device.
[0075]
The photosensitive resin composition of the present invention is applied onto a substrate by an appropriate application method such as a spinner or a coater, pre-baked (heated before exposure), exposed to exposure light having a wavelength of 220 nm or less through a predetermined mask, and PEB ( A good resist pattern can be obtained by developing after baking after exposure.
The substrate used here may be a substrate usually used in a semiconductor device or other manufacturing apparatus, and examples thereof include a silicon substrate, a glass substrate, and a nonmagnetic ceramic substrate. In addition, additional layers such as a silicon oxide layer, a wiring metal layer, an interlayer insulating film, a magnetic film, an antireflection film layer, and the like may be present on these substrates as necessary. A circuit or the like may be built in. Furthermore, these substrates may be subjected to a hydrophobic treatment according to a conventional method in order to improve the adhesion of the resist film. Examples of suitable hydrophobizing agents include 1,1,1,3,3,3-hexamethyldisilazane (HMDS).
[0076]
The resist film thickness applied on the substrate is preferably in the range of about 0.1 to 10 μm. In the case of ArF exposure, a thickness of about 0.1 to 1.5 μm is recommended.
The resist film applied on the substrate is preferably pre-baked at a temperature of about 60 to 160 ° C. for about 30 to 300 seconds. If the pre-baking temperature is low and the time is short, the residual solvent in the resist film becomes relatively large, which causes an adverse effect such as deterioration of adhesion, which is not preferable. On the other hand, if the pre-baking temperature is high and the time is long, it is not preferable because the components such as the binder and the photoacid generator of the photosensitive resin composition are decomposed.
[0077]
As a device for exposing the pre-baked resist film, a commercially available ultraviolet exposure device, X-ray exposure device, electron beam exposure device, KrF excimer exposure device, ArF excimer exposure device, F ₂ An excimer exposure apparatus or the like is used. In the present invention, an apparatus using an ArF excimer laser as an exposure light source is particularly preferable.
The post-exposure baking is performed for the purpose of causing the elimination of a protecting group using an acid as a catalyst, the purpose of eliminating a standing wave, the purpose of diffusing an acid generator or the like into the film, and the like. This post-exposure bake can be performed in the same manner as the previous pre-bake. For example, the baking temperature is about 60 to 160 ° C, preferably about 90 to 150 ° C.
[0078]
Examples of the developer for the photosensitive resin composition of the present invention include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, and aqueous ammonia, primary amines such as ethylamine and n-propylamine, and diethylamine. Secondary amines such as di-n-butylamine, tertiary amines such as triethylamine and methyldiethylamine, alcohol amines such as dimethylethanolamine and triethanolamine, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), quaternary ammonium salts such as trimethylhydroxymethylammonium hydroxide, triethylhydroxymethylammonium hydroxide, trimethylhydroxyethylammonium hydroxide, pyrrole, piperidine, 1,8 Diazabicyclo - [5.4.0] -7-undecene, 1,5-diazabicyclo - [4.3.0] -5-alkaline aqueous solution of a cyclic amine such as nonane or the like can be used.
[0079]
Furthermore, it should be used even if an appropriate amount of a hydrophilic organic solvent such as alcohols or ketones, a nonionic or anionic surfactant, a cationic surfactant or an antifoaming agent is added to the alkaline aqueous solution. Can do. In addition to the purpose of improving the resist performance, these additives are alkaline for the purpose of improving adhesion to the substrate, reducing the amount of developer used, and reducing defects caused by bubbles during development. Add to aqueous solution.
[0080]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by this.
[0081]
Synthesis Example 1 (Synthesis of Polymer A)
A hydride of a ring-opening polymer of a norbornene derivative described in JP-A-9-244247, Example 4 (repeated structural unit is described below) was synthesized according to the method described in EP 0789278 (weight average molecular weight 22000). .
[0082]
[Chemical 7]

[0083]
Synthesis Example 2 (Synthesis of Polymer B)
A hydride of a ring-opening polymer of a norbornene derivative described in JP-A-9-244247 and Example 1 (repeating structural units are described below) was synthesized according to the method described in EP 0789278 (weight average molecular weight 17000).
[0084]
[Chemical 8]

[0085]
Synthesis Example 3 (Synthesis of Polymer C)
A copolymer of norbornene, maleic anhydride, t-butyl acrylate and acrylic acid (repeated structural units are described below) was synthesized according to the method described in JP-A-10-10739, Example 7 (weight average molecular weight 17000). , Molar ratio of each repeating unit 50/25/25)
[0086]
[Chemical 9]

[0087]
Synthesis Example 4 (Synthesis of Polymer D)
A copolymer of adamantyl methacrylate and t-butyl acrylate (repeated structural units are described below) was synthesized according to the method described in JP-A-7-234511, Example 1 (weight average molecular weight 5000, each repeating Unit molar ratio 58/42).
[0088]
[Chemical Formula 10]

[0089]
Synthesis Example 5 (Synthesis of acid-decomposable low molecular weight compound a)
A mixture of 122.7 g (0.3 mol) of cholic acid and 120 ml of thionyl chloride was refluxed for 1 hour. Excess thionyl chloride was removed, the resulting solid was dissolved in 150 ml of tetrahydrofuran, 40 g (0.35 mol) of potassium-t-bucitoxide was gradually added, the reaction mixture was refluxed for 6 hours, cooled and poured into water. It is. The resulting solid was collected by filtration, washed with water and dried under reduced pressure. This crude product was recrystallized with n-hexane to obtain t-butyl cholate (the following formula) in a yield of 70%.
[0090]
Embedded image

[0091]
Synthesis Example 6 (Synthesis of Polymer E)
Polymer E was synthesized according to Synthesis Example 1 of JP-A-6-308734. That is, 30 g of polyhydroxystyrene was dissolved in tetrahydrofuran, 10 g of t-butoxypotassium was added, and 60 g of di-t-butyl dicarbonate was added dropwise at 0 ° C. with stirring, and reacted for 4 hours. After completion of the reaction, this solution was dropped into water, and the precipitated resin was dried overnight at 50 ° C. in a vacuum dryer. The obtained resin (polymer E) had a structure in which Mw was 15000 and 29% of the hydrogen atoms of the phenolic hydroxyl group were substituted with a t-butoxycarbonyl group from the results of NMR measurement.
[0092]
Examples 1-7, Comparative Examples 1-7
(Preparation of photosensitive resin composition)
In preparing the photosensitive resin component, the components listed in Table 1, that is, the polymers A, B, C, D, and E synthesized in Synthesis Examples 1 to 4 and 6, triphenylsulfonium triflate as a photoacid generator. Each component of the rate (PAG-1), the acid-decomposable low molecular weight compound (compound a) synthesized in Synthesis Example 5, a nitrogen-containing basic compound, a surfactant, and a solvent was used. The dotted line in Table 1 means that the component was not used.
Each component was mixed and then filtered through a 0.1 μm Teflon filter to prepare a photosensitive resin composition.
The amount of each component when used is as follows.
Polymer A, B, C, D, E 10g
Photoacid generator 0.06g
Acid decomposable low molecular weight compound 0.25g
Nitrogen-containing basic compound 0.04g
Surfactant 0.05g
Solvent 57.4g
[0093]
About the photosensitive resin composition adjusted in this way, the number of development defects was investigated by the following method. The evaluation results are shown in Table 2.
(Evaluation method for the number of development defects)
(1) Number of development defects -I
The photosensitive resin composition was uniformly applied on a silicon substrate subjected to hexamethyldisilazane treatment by a spin coater, and heated and dried on a hot plate at 120 ° C. for 90 seconds to form a 0.50 μm resist film. . This resist film was exposed with ArF excimer laser light through a mask, and immediately after the exposure, it was heated on a hot plate at 110 ° C. for 90 seconds. Further, the resist film was developed with an aqueous 2.38 wt% tetramethylammonium hydroxide solution at 23 ° C. for 60 seconds, rinsed with pure water for 30 seconds, and then dried. The number of development defects of the sample with the contact hole pattern thus obtained was measured using a KLA2112 machine (manufactured by KLA Tencor) (Threshold12, Pixcel Size = 0.39).
(2) Number of development defects-II
The number of development defects was measured in the same manner for the heated, developed, rinsed, and dried samples except for not exposing in (1) Number of developed defects -I.
[0094]
[Table 1]

[0095]
Each symbol in Table 1 is as follows.
PAG-1: Triphenylsulfonium triflate
N-1: Hexamethylenetetramine
N-2: 1,5-diazabicyclo [4.3.0] -5-nonene
N-3: 1,8-diazabicyclo [5.4.0] -7-undecene
N-4: 1,4-diazabicyclo [2.2.2] octane
W-1: Megafuck F176 (Dainippon Ink Co., Ltd.) (Fluorine)
W-2: Megafuck R08 (Dainippon Ink Co., Ltd.) (fluorine and silicone)
W-3: Polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical Co., Ltd.) (silicone type)
W-4: Polyoxyethylene nonylphenyl ether
S-1: Ethyl lactate
S-2: Ethyl 3-ethoxypropionate
S-3: γ-butyrolactone
S-4: Propylene carbonate
S-5: Ethylene carbonate
[0096]
[Table 2]

[0097]
As is clear from the results in Table 2, all of the photosensitive resin compositions of the present invention had very few development defects. In particular, Examples 3 to 7 using three kinds of solvents were free from development defects or few.
On the other hand, all the comparative examples have remarkably many development defects. In particular, Comparative Example 4 is a case where the solvent is composed only of ethyl lactate, and the number of development defects is more than double that of Example 1.
Comparative Example 5 is an example in which a surfactant other than those specified in the present invention is used as the surfactant, and the number of development defects is about twice as large as that in Example 1.
[0098]
【The invention's effect】
The positive photosensitive resin composition of the present invention is excellent in resist performance, coating performance, solution storage stability, and safety, and particularly excellent in that it does not cause a problem of development defects. Therefore, the positive photosensitive resin composition of the present invention is particularly effective for lithography using ArF excimer laser light as an exposure light source.

Claims (8)

(A) a polymer having a cyclic aliphatic hydrocarbon skeleton, which is decomposed by the action of an acid and becomes alkali-soluble,
(B) a compound that generates an acid by actinic rays,
(C) a nitrogen-containing basic compound,
(D) fluorine-based and / or silicon-based surfactant, and (E) (a) ethyl lactate in an amount of 60 to 90% by weight based on the total solvent, and (b) ethyl 3-ethoxypropionate as the total solvent A positive photosensitive resin composition comprising a solvent in an amount of 10 to 40% by weight based on the weight.  2. The positive type according to claim 1, wherein the solvent further comprises (c) a solvent having a boiling point of 180 ° C. or more and a solubility parameter of 12 or more, based on the total solvent. Photosensitive resin composition.  (C) The positive photosensitive resin composition according to claim 2, wherein the solvent is at least one selected from γ-butyrolactone, ethylene carbonate, and propylene carbonate.  (A) A polymer having a cycloaliphatic hydrocarbon skeleton, wherein the number of carbon atoms forming the cycloaliphatic hydrocarbon skeleton of the polymer which is decomposed by the action of an acid and becomes alkali-soluble is 5 to 25, The positive photosensitive resin composition according to any one of claims 1 to 3.  The positive type according to any one of claims 1 to 4, wherein the nitrogen-containing basic compound (C) is at least one selected from organic amines, basic ammonium salts, and basic sulfonium salts. Photosensitive resin composition.  2. A low molecular acid-decomposable dissolution inhibiting compound having a molecular weight of 2000 or less, having a group that can be decomposed by the action of an acid, and alkali solubility being increased by the action of an acid. The positive photosensitive composition in any one of -5.  The positive photosensitive resin composition according to claim 1, wherein the active light is far ultraviolet light having a wavelength of 220 nm or less.   A pattern forming method comprising: forming a film with the positive photosensitive resin composition according to claim 1, and exposing and developing the film.