JP4023931B2 - Positive radiation sensitive resin composition - Google Patents

Description

１−メトキシ−１−メチルエトキシ基などのケタール基、メトキシカルボニルオキシ基、エトキシカルボニルオキシ基、ｎ−プロピルオキシカルボニルオキシ基、ｉｓｏ−プロピルオキシカルボニルオキシ基、ｎ−ブトキシカルボニルオキシ基、ｓｅｃ−ブトキシカルボニルオキシ基、ｉｓｏ−ブトキシカルボニルオキシ基、t−ブトキシカルボニルオキシ基、メンチルオキシカルボニルオキシ基など

、本明細書に於いて、酸分解性保護基は、フェノール性水酸基由来の酸素原子を含めて表わしている。）これらのうち特に好ましくは下記一般式（Ｉ）で表される基である。
【００１４】
【化２】

【００１５】
（ただし、Ｒ¹ 及びＲ² は独立に水素原子、置換されていても良いアルキル基または置換されていても良いアルコキシ基を表し、Ｒ³ は置換されていても良いアルキル基を表す。また、Ｒ¹ とＲ³ とは互いに結合して環を形成していても良い。）
Ｒ¹ 〜Ｒ³ で表わされるアルキル基及びアルコキシ基の炭素数は好ましくは１〜２０、より好ましくは１〜１０である。
該成分（Ａ）としては、これらを単独で用いても、これらのうちの複数の種類を混合して用いても良い。また、該フェノール性水酸基が酸分解性保護基で保護された樹脂においては、該酸分解性保護基を単独で用いても、複数種用いても良く、樹脂の１分子中に複数の種類の酸分解性保護基を有する共重合体であっても良い。
【００１６】
該成分（Ａ）としては、該フェノール性水酸基が酸分解性保護基で保護された樹脂を用いた場合の方がレジストの露光部と未露光部分の溶解性の差が大きくなり、現像後のレジスト形状および解像性が向上するので好ましい。
酸分解性保護基によるアルカリ可溶性樹脂のフェノール性水酸基の保護率は特に限定されないが、５〜６０％が好ましく、特に１０〜５０％が好ましい。保護率が上記記載よりも小さすぎると、レジスト膜の未露光部の残膜率が低下し、解像性が低下する傾向がある。また、保護率が大きすぎると、現像時に現像液をはじいてしまい、現像できなくなる恐れがある。
【００１７】
該成分（Ａ）として用いる樹脂の重量平均分子量Ｍｗは、レジスト膜が形成でき露光後にアルカリ現像液で現像できる範囲であれば使用することができるが、好ましくはポリスチレン換算値（ゲル・パーミエーション・クロマトグラフィ測定）で、通常３，０００以上１００，０００以下、好ましくは４，０００以上５０，０００以下さらに好ましくは６，０００以上４０，０００以下のものが用いられる。
該樹脂の重量平均分子量が、この範囲よりも大きいと露光部分のアルカリ現像液に対する溶解性が小さくなり、良好なレジストのパターンが得られない怖れがある。また該樹脂の重量平均分子量が、この範囲よりも小さいと良好なレジスト塗膜が得られない怖れがある。
【００１８】
フェノール性水酸基含有アルカリ可溶性樹脂を上記範囲に調整する方法としては、分別沈殿法、分別溶解法、カラム分別法、超遠心分離法等があるが、いずれかの方法を用いてもよい。又、該樹脂の分子量分布Ｍｗ／Ｍｎは１以上１．５以下であるのが、解像力の点で好ましい。
成分（Ｂ）（以下、溶解抑制剤という）は、該組成物に添加することにより該成分（Ａ）のアルカリ溶解速度を低下し、露光後室温または加熱下でレジスト膜の溶解性を向上させることにより溶解コントラストを向上させる効果を持っており、部分構造として、酸の作用により分解してアルカリ可溶性を付与する基、具体的には水酸基を生成しうる構造を有する化合物であれば特に制限はなく、アセタール構造、カーボネート構造のいずれでも可能であるが、カーボネート構造である場合が好ましく、特に前記樹脂（Ａ）の酸分解性保護基がアセタール基である場合との組合せに於いて特に有利である。具体的にはエタノール、プロパノール、ブタノール、シクロヘキサノール、１，４−シクロヘキサンジオール、エチレングリコール、プロピレングリコール、グリセリンなどのアルコール類、フェノール、クレゾール、レゾルシノール、ピロガロールなどのフェノール類、ｏ−ヒドロキシベンゾフェノン、ｍ−ヒドロキシベンゾフェノン、ｐ−ヒドロキシベンゾフェノン、４，４’−ジヒドロキシベンゾフェノン、２，３，４−トリヒドロキシベンゾフェノン、２，３，４，４’−テトラヒドロキシベンゾフェノン、２，３，４，２’，４’−ペンタヒドロキシベンゾフェノンなどのヒドロキシベンゾフェノン類または、特開平６−５１５１９号公報に記載されているようなフェノール類とアルデヒド或いはケトンなどとを縮合する事によって得られる多核フェノール類等の水酸基含有化合物の水酸基の少なくとも一部をメトキシカルボニルオキシ基、エトキシカルボニルオキシ基、ｎ−プロピルオキシカルボニルオキシ基、ｉｓｏ−プロピルオキシカルボニルオキシ基、ｎ−ブトキシカルボニルオキシ基、ｓｅｃ−ブトキシカルボニルオキシ基、ｉｓｏ−ブトキシカルボニルオキシ基、ｔｅｒｔ−ブチトキシカルボニルオキシ基、メンチルオキシカルボニルオキシ基などのカーボネート基、より具体的には置換基を有していてもよいアルコキシカルボニルオキシ基で保護した化合物が挙げられる。該アルコキシ基の炭素数は通常１〜２０程度である。
【００１９】
これらのうち、フェノール類とアルデヒド或いはケトンなどとを縮合する事によって得られる多核フェノール類の水酸基の少なくとも一部をカーボネート基で保護した化合物が好ましい。フェノール類はより具体的には、アルキル基等の置換基を有していてもよい１〜３価のフェノールを意味し、アルデヒドとしてはホルムアルデヒド、アセトアルデヒド、アルキル基及び／又は水酸基等の置換基を有していてもよいベンズアルデヒドのＣ₁ 〜Ｃ₁₅の脂肪族又は芳香族アルデヒドが、又ケトンとしては、アセトン、アルキル基及び／又は水酸基等の置換基を有していてもよいアセトフェノン等のＣ₃ 〜Ｃ₁₅、脂肪族又は芳香族ケトンが挙げられる。尚、成分（Ｂ）は成分（Ａ）の樹脂とは区別されるものであり、従って、好ましい分子量範囲としては２００以上３，０００未満である。この範囲よりも分子量が小さいと十分な溶解抑止効果が得られず、この範囲よりも分子量が大きいと露光後の溶解性の低下が起こり、レジストのパターン形状が悪くなる傾向にある。
【００２０】
多核フェノール類の水酸基の少なくとも一部をカーボネート基で保護した化合物の場合、１分子中のフェノール性水酸基の保護率は、高いほど溶解抑制効果が大きくなるので好ましく、平均して４０％以上１００％以下の保護率が好ましい。より好ましくは６０％以上１００％以下、更に好ましくは８０％以上１００％以下である。
【００２１】
該溶解抑制剤の添加量は該樹脂成分（Ａ）１００重量部に対して溶解抑制剤（Ｂ）１〜５０重量部、好ましくは５〜４０重量部の割合で用いられる。
溶解抑制剤の量をこの範囲で用いると、露光部と未露光部との間で十分な溶解速度変化が得られ、特に良好なレジストパターンが得られる。溶解抑制剤が多すぎる場合には、露光後未分解の溶解抑制剤が現像液に溶解せずレジストパターン間に残さが残る場合がある。
【００２２】
本発明で使用する成分（Ｃ）（以下、光酸発生剤という）としては、露光に用いられる活性光線または放射線によって酸を発生するものであれば特に限定されるものではなく、従来公知のものが使用できるが、具体的には、たとえばトリス（トリクロロメチル）−ｓ−トリアジン、トリス（トリブロモメチル）−ｓ−トリアジン、トリス（ジブロモメチル）−ｓ−トリアジン、２，４−ビス（トリブロモメチル）−６−ｐ−メトキシフェニル−ｓ−トリアジンなどのハロゲン含有ｓ−トリアジン誘導体、１，２，３，４−テトラブロモブタン、１，１，２，２−テトラブロモエタン、四臭化炭素、ヨードホルムなどのハロゲン置換パラフィン系炭化水素、ヘキサブロモシクロヘキサン、ヘキサクロロシクロヘキサン、ヘキサブロモシクロドデカンなどのハロゲン置換シクロパラフィン系炭化水素、ビス（トリクロロメチル）ベンゼン、ビス（トリブロモメチル）ベンゼンなどのハロゲン含有ベンゼン誘導体、トリブロモメチルフェニルスルホン、トリクロロメチルフェニルスルホン、２，３−ジブロモスルホランなどのハロゲン含有スルホン化合物、トリス（２，３−ジブロモプロピル）イソシアヌレートなどのハロゲン含有イソシアヌレート誘導体、トリフェニルスルホニウムクロライド、トリフェニルスルホニウムメタンスルホネート、トリフェニルスルホニウムトリフルオロメチルスルホネート、トリフェニルスルホニウム、ｐ−トルエンスルホネート、トリフェニルスルホニウムテトラフルオロボレート、トリフェニルスルホニウムヘキサフルオロアルセネート、トリフェニルスルホニウムヘキサフルオロホスホネートなどのスルホニウム塩、ジフェニルヨードニウムトリフルオロメチルスルホネート、ジフェニルヨードニウムｐ−トルエンスルホネート、ジフェニルヨードニウムテトラフルオロボレート、ジフェニルヨードニウムヘキサフルオロアルセネート、ジフェニルヨードニウムヘキサフルオロホスホネートなどのヨードニウム塩、ｐ−トルエンスルホン酸メチル、ｐ−トルエンスルホン酸エチル、ｐ−トルエンスルホン酸ブチル、ｐ−トルエンスルホン酸フェニル、１，２，３−トリ（ｐ−トルエンスルホニルオキシ）ベンゼン、ｐ−トルエンスルホン酸ベンゾインエステル、メタンスルホン酸メチル、メタンスルホン酸エチル、メタンスルホン酸ブチル、１，２，３−トリ（メタンスルホニルオキシ）ベンゼン、メタンスルホン酸フェニル、メタンスルホン酸ベンゾインエステル、トリフルオロメタンスルホン酸メチル、トリフルオロメタンスルホン酸エチル、トリフルオロメタンスルホン酸ブチル、１，２，３−トリ（トリフルオロメタンスルホニルオキシ）ベンゼン、トリフルオロメタンスルホン酸フェニル、トリフルオロメタンスルホン酸ベンゾインエステル、などのスルホン酸エステル類、ジフェニルジスルホンなどのジスルホン類、フェニルカルボニルフェニルスルホニルジアゾメタンなどのカルボニルスルホニルジアゾメタン類、ビス（フェニルスルホニル）メタン、ビス（シクロヘキシルスルホニル）メタンなどのビススルホニルメタン類、ビス（フェニルスルホニル）ジアゾメタン、ビス（シクロヘキシルスルホニル）ジアゾメタンなどのビススルホニルジアゾメタン類、ｏ−ニトロベンジル−ｐ−トルエンスルホネートなどのｏ−ニトロベンジルエステル類、Ｎ，Ｎ’−ジ（フェニルスルホニル）ヒドラジドなどのスルホンヒドラジド類、フタルイミノトリフルオロメチルスルホネート、フタルイミノｐ−トルエンスルホネート、フタルイミノカンファースルホネートなどのイミノスルホネート類などが挙げられる。これらの中でも、露光後スルホン酸を発生する化合物が好適に用いられ、なかでも下記一般式（II）に示すビスフェニルスルホニルジアゾメタン類が特に好ましい。
【００２３】
【化３】

【００２４】
（ただし、Ｒ⁴ 、Ｒ⁵ は独立に置換されていても良い直鎖状、分枝状または環状アルキル基、置換されていても良いアリル基、置換されていても良いアラルキル基を表す。）
【００２５】
本発明の感放射線性組成物においては、樹脂成分（Ａ）１００重量部に対して光酸発生剤（Ｃ）０．００１〜３０重量部、好ましくは０．０５〜２０重量部の割合で用いられる。
光酸発生剤の量がこの範囲よりも少ないと感度が劣り、この範囲よりも多いと、光酸発生剤によるレジスト膜の透明性の低下によりレジストパターンが台形になり解像力の低下を引き起こす恐れがある。
成分（Ｄ）の有機カルボン酸は、環境からの塩基性物質の侵入によるレジスト性能の低下を抑制するのに効果があり、特に溶解抑制剤（Ｂ）と組み合わせて使用することによって、酸性物質に対する耐性も保持したまま、従来知られていたよりも良好な環境耐性を実現できる。
【００２６】
本発明において用いることのできる有機カルボン酸の具体例としては、蟻酸、酢酸、プロピオン酸、ｎ−酪酸、ｉｓｏ−酪酸、蓚酸、マロン酸、琥珀酸、グルタル酸、アジピン酸、アクリル酸、メタクリル酸、マレイン酸、フマル酸などの脂肪族カルボン酸、ピルビン酸などのケトカルボン酸、安息香酸、サリチル酸、ｍ−ヒドロキシ安息香酸、ｐ−ヒドロキシ安息香酸、２，４−ジヒドロキシ安息香酸、２，５−ジヒドロキシ安息香酸、２，６−ジヒドロキシ安息香酸、フタル酸、テレフタル酸、イソフタル酸などの芳香族カルボン酸、または商品名ＳＡＸ（三井東圧化学製）として市販されている芳香族カルボン酸の構造単位を含むポリマーなどを用いることができる。該成分（Ｄ）の添加量は、該成分（Ａ）１００重量部に対して０．０００１〜１０重量部、好ましくは０．００１〜５重量部の割合で用いられる。
【００２７】
成分（Ｄ）を上記範囲の量で用いると、環境から侵入する塩基性物質の露光部への拡散を防止する効果が得られ、良好なレジストパターンが得られ好ましい。ただし、過剰に多いとレジストの未露光部残膜率が落ちるため好ましくない。
本発明の感放射線性樹脂組成物には添加剤を加えることができ、有機塩基、界面活性剤、吸光剤などが挙げられる。
有機塩基は光酸発生剤から発生した酸の未露光部への拡散を防ぐもので、具体的には、アルキルアミン類、アリールアミン類、ピリジン類、ピリジニウム塩類などが挙げられ、特開平５−１２７３６９号、特開平５−２３２７０６号、特開平７−９２６７８号、特開平９−１７９３００号、特開平９−３２５４９６号に開示されている化合物などを用いることができる。
【００２８】
有機塩基の添加量は成分（Ａ）の樹脂１００重量部に対して、有機塩基０．０００１〜５重量部、好ましくは０．００１〜２重量部の割合で用いられる。
有機塩基を上記範囲の量で用いると、十分な酸の未露光部への拡散を防止する効果が得られ、良好なレジストパターンが得られ好ましい。但し、過剰に多いとレジストの感度が落ちるため好ましくない。
【００２９】
界面活性剤は、感放射線性樹脂組成物の塗膜性を良くし、スピンコート時の膜厚均一性を改善したり、感放射線性樹脂組成物の現像性を良くする目的で添加される。
このような目的で使用できる界面活性剤としては、たとえば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レイルエーテル、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、ポリオキシエチレングリコールラウリテート、ポリオキシエチレングリコールジステアレート、エフトップＥＦ３０１、ＥＦ３０３、ＥＦ３５２（トーケムプロダクツ社製）、メガファックＦ１７０、Ｆ１７１、Ｆ１７２、Ｆ１７３（大日本インキ社製）、フロラードＦＣ４３０、ＦＣ４３１、ＦＣ１７０Ｃ（住友３Ｍ社製）、アサヒガードＡＧ７１０、サーフロンＳ−３８２、ＳＣ―１０１、ＳＣ−１０２、ＳＣ−１０３、ＳＣ−１０４、ＳＣ−１０５、ＳＣ−１０６（旭硝子社製）、ＫＰ３４１（信越化学社製）、ポリフローＮｏ．７５、Ｎｏ．９５（共栄社油脂化学工業製）などを挙げることができる。
【００３０】
これらの界面活性剤は単独であるいは２種以上を混合で用いることができ、通常樹脂成分（Ａ）１００重量部に対して、界面活性剤０．０１重量部以上３重量部以下の割合で使用される。
アルミなどの反射率の高い基板上でレジストの画像形成をする場合には、基板からの露光光の反射によるレジストパターン形状の劣化を防ぐために、吸光剤を加えることができる。このような目的に使用される吸光剤の例としては、ナフトキノンジアジド化合物、ベンゾフェノン類、ナフタレンやアントラセンなどの縮合芳香族環含有化合物などを挙げることができる。
【００３１】
本発明の感放射線性樹脂組成物は、上記各成分を適当な溶媒に溶解して用いる。溶媒としては、本発明の各成分及びその他の添加剤に対して、十分な溶解度を持ち良好な塗膜性を与える溶媒であれば特に制限はないが、２−ヘキサノン、シクロヘキサノンなどのケトン系溶媒、メチルセロソルブ、エチルセロソルブ、メチルセロソルブアセテート、エチルセロソルブアセテートなどのセロソルブ系溶媒、ジエチルオキサレート、ピルビン酸エチル、エチル−２−ヒドロキシブチレート、エチルアセトアセテート、酢酸ブチル、酢酸アミル、酪酸エチル、酪酸ブチル、乳酸メチル、乳酸エチル、３−メトキシプロピオン酸メチルなどのエステル系溶媒、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エチルエーテル、プロピレングリコールモノブチルエーテル、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エチルエーテルアセテート、プロピレングリコールモノブチルエーテルアセテート、ジプロピレングリコールジメチルエーテルなどのプロピレングリコール系溶媒、シクロヘキサノン、メチルアミルケトン、２−ヘプタノンなどのケトン系溶媒、あるいはこれらの混合溶媒、あるいはさらに芳香族炭化水素を添加したものなどが挙げられる。溶媒の使用割合は、感放射線性樹脂組成物中の固形分の総量に対して重量比として１〜２０倍の範囲であることが好ましい。
【００３２】
本発明の感放射線性樹脂組成物を用いて半導体基板上にレジストパターンを形成する場合には、通常上記のような溶媒に溶解した本発明の感放射線性樹脂組成物を半導体基板上に塗布し、プリベーク、露光によるパターンの転写、露光後加熱（ポスト・エクスポージャー・ベーク；ＰＥＢ）、現像の各工程を経てフォトレジストとして使用することができる。半導体基板は、通常半導体製造用基板として使用されているものであり、シリコン基板、ガリウムヒ素基板などである。
【００３３】
塗布には通常スピンコーターが使用され、露光には、高圧水銀灯の４３６ｎｍ、３６５ｎｍの光、低圧水銀灯の２５４ｎｍ、またはエキシマレーザーなどを光源とする１５７ｎｍ、１９３ｎｍ、２２２ｎｍ、２４８ｎｍの光、Ｘ線、電子線などが好適に用いられる。露光の際の光は、単色光でなくブロードであってもよい。また、位相シフト法、輪帯照明などの超解像露光技術による露光も適用可能である。
【００３４】
本発明の感放射線性樹脂組成物の現像液には、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、メタケイ酸ナトリウム、アンモニア水などの無機アルカリ類、エチルアミン、ｎ−プロピルアミンなどの第１級アミン類、ジエチルアミン、ジ−ｎ−プロピルアミンなどの第２級アミン類、トリエチルアミン、Ｎ、Ｎ−ジエチルメチルアミンなどの第３級アミン類、テトラメチルアンモニウムハイドロオキシド、トリメチルヒドロキシエチルアンモニウムハイドロオキシドなどの第４級アンモニウム塩、もしくはこれにアルコール、界面活性剤などを添加したものを使用することができる。
【００３５】
本発明の感放射線性樹脂組成物は超ＬＳＩの製造のみならず一般のＩＣ製造用、マスク製造用、画像形成用、液晶画面製造用、カラーフィルター製造用あるいはオフセット印刷用としても有用である。特に、ＫｒＦエキシマレーザー露光用として有用である。
【００３６】
【実施例】
次に実施例を挙げて本発明を更に詳しく説明するが、本発明はその要旨を越えない限り実施例により何等制約は受けない。
合成例１（１−エトキシエチル化ポリヒドロキシスチレンの合成）
窒素導入管、撹拌機、温度計を備えた１Ｌの四つ口フラスコにポリヒドロキシスチレン（日本曹達（株）製、重量平均分子量１５，９００、Ｍｗ／Ｍｎ１．１２）３０ｇと１，３−ジオキソラン３００ｍＬとを加え、均一に溶解させたあと、エチルビニルエーテル１５．０ｇを加え、ウオーターバスで４０℃に加熱した。これに、３６％塩酸０．３ｇを加え、４時間撹拌を続けた。反応後、この反応溶液に２８％アンモニア水３ｍＬを加え３０分攪拌した。この反応液を純水３Ｌ中に滴下して得られた沈殿を濾過した。さらに、この沈殿物をアセトンに溶解させ、その溶液を純水に滴下し沈殿させることにより目的のポリマーを回収した。析出したポリマーを真空乾燥して、３７．１ｇの１−エトキシエチル化ポリビニルフェノールを得た。
得られたポリマーを重水素化アセトンに溶解し、プロトンＮＭＲスペクトルを測定したところ、δ値６．２〜７．０の芳香族水素のシグナルとδ値５．２〜５．５のアセタールメチン水素のシグナルとの面積比は、１０．２：１であった。この結果よりアセタール化率をもとめると３９．４％となった。
【００３７】
合成例２（溶解抑制剤１の合成）
窒素導入管、撹拌機、温度計を備えた３００ｍＬの四つ口フラスコに下記構造式（ＩＩＩ）
【００３８】
【化４】

【００３９】
で表される化合物（Ｂｉｓ−ＲＳ３Ｐ、本州化学（株）製）４．２８ｇと１，３−ジオキソラン２０ｍＬとを加え、均一に溶解させたあと、メンチルクロロフォルメート５．４７ｇを加え、ウオーターバスで４０℃に加熱した。これに、トリエチルアミン２．５３ｇの１，３−ジオキソラン５ｍＬ溶液を５分間で滴下し、滴下終了後３時間撹拌を続けた。反応後、この反応溶液を純水４００ｍＬ中に滴下して得られた沈殿を濾過した。さらに、この沈殿物をアセトンに溶解させ、その溶液を純水に滴下し沈殿させることによりメンチルカーボネート基を有する目的物を回収した。析出した固体を真空乾燥して、４．８９ｇの溶解抑制剤１を得た。
【００４０】
得られた溶解抑制剤１を重水素化アセトンに溶解し、プロトンＮＭＲスペクトルを測定したところ、δ値７．０〜７．４の芳香族水素のシグナルとδ値４．４〜４．７のメチン水素のシグナルとの面積比は、２．７４：１であった。この結果よりメンチルカーボネート基によるフェノール性水酸基の保護率をもとめると９４．９％となった。
【００４１】
合成例３（溶解抑制剤２の合成）
窒素導入管、撹拌機、温度計を備えた３００ｍＬの四つ口フラスコに前記構造式（ＩＩＩ）で表される化合物（Ｂｉｓ−ＲＳ３Ｐ、本州化学（株）製）４．２８ｇとアセトン３０ｍＬとを加え、均一に溶解させたあと、Ｎ，Ｎ−ジメチルアミノピリジン０．０５ｇを加え、ウオーターバスで４０℃に加熱した。これに、ジ（ｔｅｒｔ−ブチル）ジカーボネート１１．０ｇを１０分間で滴下し、滴下終了後４時間撹拌を続けた。反応後、この反応溶液を純水１Ｌ中に滴下して得られた沈殿を濾過した。さらに、この沈殿物をアセトンに溶解させ、その溶液を純水に滴下し沈殿させることにより目的物を回収した。析出した固体を真空乾燥して、９．０２ｇの溶解抑制剤２を得た。
【００４２】
得られた溶解抑制剤を重水素化アセトンに溶解し、プロトンＮＭＲスペクトルを測定したところ、δ値７．０〜７．４の芳香族水素のシグナルとδ値１．３〜１．７のｔｅｒｔ−ブチル基水素のシグナルとの面積比は、１．９６：６．７４であった。この結果よりｔｅｒｔ−ブチルカーボネート基によるフェノール性水酸基の保護率をもとめると９９．３％となった。
【００４３】
合成例４（光酸発生剤の合成）
（１）窒素導入管、攪拌機、温度計を備えた１Ｌの四つ口フラスコにパラホルムアルデヒド１２．１ｇとトルエン６０ｇを加え攪拌した後に、濃塩酸１２０ｍＬを加え、ウオーターバスで４０℃に加熱した。これに、シクロヘキサンチオール３５．４ｇのトルエン溶液６０ｇを２０分間で滴下した。滴下終了後、反応液を５０℃に保ちながら攪拌した。ＴＬＣにより反応終了確認後、水層を廃棄し飽和炭酸ソーダ水溶液でアルカリ性にしクロロメチルシクロヘキシルスルフィドのトルエン溶液を得た。
（２）４−メトキシベンゼンチオール７．４ｇを２００ｍＬフラスコに入れ、水酸化ナトリウムの５ｗｔ％エタノール溶液４５．２ｇを加え攪拌をした。このフラスコを水冷しながら、（１）で得られたクロロメチルシクロヘキシルスルフィドのトルエン溶液２７．８ｇを５分間で滴下した。２時間攪拌後、７０℃に昇温してさらに１時間攪拌した。この反応溶液にタングステン酸ナトリウム５００ｍｇを加えた後、３０％過酸化水素水２５ｇを１時間かけて加え５時間攪拌した。トルエンで抽出し無水硫酸ナトリウムで乾燥後、溶媒を減圧留去する事により、シクロヘキシルスルホニル−（４−メトキシフェニルスルホニル）メタンを得た。
（３）（２）で合成したシクロヘキシルスルホニルヘキシルスルホニル−（４−メトキシフェニルスルホニル）メタン３．０ｇをフラスコに入れ、エタノール１００ｍＬを加え攪拌した。さらに、この溶液に水酸化ナトリウムの５ｗｔ％エタノール溶液８．０ｇを加え攪拌した。この反応溶液を−５℃から−１０℃まで冷却し純水３５ｍＬを加えた後、ｐ−トルエンスルホニルアジド２．０ｇのエタノール溶液１０ｍＬを５分間かけて滴下し、３時間攪拌し静置した。一晩放置後析出物を濾取し粗結晶を得た。この粗結晶をエタノールで再結晶することによりシクロヘキシルスルホニル−（４−メトキシフェニルスルホニル）ジアゾメタンを得た。
【００４４】
実施例１
合成例１で合成した樹脂０．６０ｇ、合成例２で合成した溶解抑制剤１ ０．０６ｇ、合成例４で合成した光酸発生剤０．０１２ｇ、有機カルボン酸としてサリチル酸０．００２３ｇ、添加剤として下記構造式（ＩＶ）で示されるビス（２−ヒドロキシエチル）イミノトリス（ヒドロキシメチル）メタン０．００１１ｇ、
【００４５】
【化５】

【００４６】
界面活性剤としてフロラードＦＣ４３０（住友３Ｍ社製）０．０００４ｇおよび溶媒としてプロピレングリコールモノメチルエーテルアセテート３．１５ｇ、乳酸エチル０．６５ｇを混合し、レジスト感光液とした。塩基性基板として、シリコン基板上にポリ（Ｎ−フェニルマレイミド）を８００ｎｍの膜厚で塗布した基板を用意し、レジスト感光液をこの基板上にスピンコートし、ホットプレート上で９０℃、６０秒間ベークし、膜厚０．７２μｍのレジスト膜とした。さらに、酸性の保護膜に対する耐性を評価するために、このレジスト膜上に、純水中にポリビニルピロリドンとパーフルオロオクチルスルホン酸とを固形分濃度２．５ｗｔ％、ｐＨ２．０になるように溶解した水溶液を膜厚４０ｎｍになるようにスピンコートし、６０℃、６０秒間ベークした。このレジスト膜をニコン社製ＫｒＦエキシマレーザ縮小投影露光装置（ＮＡ＝０．４２）を用い、露光した後、ホットプレート上で１１０℃、６０秒間ベークした。この後、このレジスト膜をテトラメチルアンモニウムヒドロキシド２．３８重量％水溶液で１分間現像した。この現像後に得られたレジストパターンを走査電子顕微鏡で観察することにより解像力、パターン形状、レジスト膜表面荒れ、基板付近でのレジストの裾引きを評価した。
【００４７】
０．３０μｍのライン・アンド・スペースが０．３０μｍの線幅で解像する露光量を最適露光感度とし、このときのライン・アンド・スペース・パターンでの最小解像寸法を解像力と定義した。また、レジスト膜の表面荒れについては、最適露光感度での０．３０μｍのライン・アンド・スペースのレジスト膜表面を走査電子顕微鏡で観察することにより評価した。又、基板付近でのレジストの裾引きについては、同様に最適露光感度での０．３０μｍのライン・アンド・スペースのレジスト断面形状を走査電子顕微鏡で観察し、裾引きの程度によって５段階のランク付けを行った（５：全く無し、４：ほとんどなし、３：あり（不良）、２：かなりあり（不良）、１：著しくあり（不良））。
その結果を表−１に示す。
【００４８】
実施例２
溶解抑制剤を合成例３の溶解抑止剤２に変えた以外は実施例１と全く同様にして、レジストの解像力、パターン形状、レジスト膜表面荒れ、基板付近でのレジストの裾引きを評価した。
その結果を表−１に示す。
【００４９】
比較例１
有機カルボン酸成分としてのサリチル酸を加えなかった以外は実施例１と全く同様にして、レジストの解像力、パターン形状、レジスト膜表面荒れ、基板付近でのレジストの裾引きを評価した。
その結果を表−１に示す。
【００５０】
比較例２
有機カルボン酸成分としてのサリチル酸を加えなかった以外は実施例２と全く同様にして、レジストの解像力、パターン形状、レジスト膜表面荒れ、基板付近でのレジストの裾引きを評価した。
その結果を表−１に示す。
【００５１】
比較例３
溶解抑制剤１を加えなかった以外は実施例１と全く同様にして、レジストの解像力、パターン形状、レジスト膜表面荒れ、基板付近でのレジストの裾引きを評価した。
その結果を表−１に示す。
【００５２】
【化６】

【００５３】
【表１】

【００５４】
【発明の効果】
本発明の感放射線性樹脂組成物は、化学増幅型のポジ型感放射線性樹脂組成物に於て、上記成分（Ｂ）と（Ｄ）を併用することにより良好な感度・解像度を維持し、しかも基板及び上層保護膜等の環境耐性に優れ、膜アレ、裾引き等のない良好な形状のレジストパターンを形成しうる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a positive radiation sensitive composition. Specifically, the present invention relates to a positive radiation-sensitive resin composition that is excellent in pattern shape, resolution, and environmental resistance and is suitable for a positive resist for forming a semiconductor integrated circuit.
[0002]
[Prior art]
Waves of higher integration and higher density of semiconductor integrated circuits are remarkably fast. Particularly, DRAM (Dynamic Random Access Memory) has already started mass production of 16 Mbit, and some of them have a storage capacity of 64 Mbit and 256 Mbit in this century. Production is said to begin. A design rule of 0.30 μm and 0.25 μm is applied to a line width of 0.50 μm at 16 Mbit and 64 Mbit and 256 Mbit DRAM, and development of a photoresist corresponding to such quarter-micron lithography is urgently required.
As lithography corresponding to a quarter micron or even smaller semiconductor device design rule, X-ray lithography, electron beam lithography, and deep ultraviolet lithography represented by KrF excimer laser are used.
[0003]
By the way, a photoresist containing an alkali-soluble novolak resin and a naphthoquinonediazide-based photosensitizer has been conventionally used for g-line or i-line lithography. However, when exposure is performed using X-rays, electron beams, or far-ultraviolet rays. However, a good pattern profile cannot be obtained, and the resolution is inferior. Therefore, novolak-naphthoquinonediazide-based materials are unsuitable for lithography smaller than quarter microns. In addition, a resist material with higher sensitivity in terms of throughput is also demanded.
[0004]
Therefore, H.P. A resist called a chemical amplification type proposed by Ito et al. Has been studied (Polm. Eng. Sci., 23, 1012 (1983)). This is a resin that has a photoacid generator that generates acid upon irradiation with actinic rays or radiation, and a functional group that is easily eliminated by acid, and the dissolution rate in an alkali developer changes before and after the elimination of the functional group. Is a positive photosensitive composition.
[0005]
Incidentally, as a problem peculiar to such a chemically amplified resist, there is a so-called environmental resistance problem. In other words, chemically amplified resists utilize the catalytic action of a small amount of acid generated by exposure, so the sensitivity changes or pattern shape is affected by acidic or basic substances that enter the resist film from the surrounding environment. It becomes easy to cause deterioration.
[0006]
Methods for solving these problems include applying a protective film on the resist film, using a chemical filter that adsorbs basic substances in the environment, and adding basic substances such as amines to the resist. The method of doing is known.
However, each of these methods has advantages and disadvantages. For example, when a protective film is used as an upper layer of the resist film, if a weakly acidic protective film is used to reduce the influence of the basic substance in the air, the surface of the resist film However, the acid of the protective film becomes alkali-soluble and surface roughness occurs. In addition, the change in the resist bottom shape due to the difference in the type of the substrate has been difficult to solve by the above method.
[0007]
For example, Japanese Patent Application Laid-Open No. 6-51519 discloses a combination of an alkali-soluble resin and a low-molecular acid-decomposable dissolution inhibiting compound, and describes that there is an effect of improving sensitivity, resolution, and pattern profile. However, as a result of our study, it has been found that the bottom portion of the resist has a tail shape when patterned on a basic substrate.
In addition, in JP-A-7-92679, JP-A-7-140663, JP-A-9-138505, JP-A-10-20504, JP-A-10-55069, etc., by adding an organic carboxylic acid compound, sensitivity and resolution are improved. Although it is disclosed that a resist material excellent in resist characteristics such as etching resistance, storage stability and process margin can be provided, as a result of our study, this alone is the resist surface when an acidic upper protective film is used. It has been found that there is a problem that the film becomes rough.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a positive-type radiation-sensitive resin composition that maintains resist performance such as sensitivity and resolution and has improved environmental resistance that is not affected by the substrate and the upper protective film.
[0009]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the inventors of the present invention can generate specific components in a chemically amplified photoresist, that is, a group that decomposes under the action of an acid to impart alkali solubility. By combining a compound having a partial structure with an organic carboxylic acid, the environmental resistance can be improved at the same time in both acidic and basic environments while maintaining performance such as sensitivity and resolution. It has been found that the surface roughness and resist tailing are suppressed, and the present invention has been achieved. That is, the gist of the present invention is (A) a phenolic hydroxyl group-containing alkali-soluble resin or a resin in which at least a part of the hydroxyl group is protected with an acid-decomposable protecting group, and (B) an alkali-soluble property by being decomposed by the action of an acid. And (C) a positive radiation sensitive resin composition containing a compound having a partial structure capable of generating a group and (C) a compound capable of decomposing by actinic rays or radiation to generate an acid, and (D) an organic carboxylic acid In a positive radiation sensitive resin composition characterized by containing.
Hereinafter, the present invention will be described in detail.
[0010]
In the present invention, the phenolic hydroxyl group-containing alkali-soluble resin as the component (A) can be used as long as the exposed portion becomes alkali-soluble during development and is eluted in an alkali developer and has a uniform resist film forming ability. However, polyhydroxystyrenes such as a novolac resin, a polymerization obtained by hydroxystyrene alone or a resin obtained by copolymerizing hydroxystyrene and various vinyl monomers can be used. Here, as long as the polyhydroxystyrene is a polymer having a structure derived from hydroxystyrene as a partial structure, it may be homopolymerized or copolymerized, and has a substituent on the benzene ring or other part. Including In the case of a novolak resin, phenol, o-cresol, m-cresol, p-cresol, resorcinol, pyrogallol, xylenol, etc. can be used as the phenol component, and formaldehyde, acetaldehyde, benzaldehyde, acetone, etc. can be used as the aldehyde or ketone component. Can be used. Moreover, as a vinyl monomer copolymerized with hydroxystyrene, a compound containing an ethylenically unsaturated double bond such as acrylic acid, vinyl alcohol, or a derivative thereof can be used.
[0011]
In the case of a resist for exposure with far ultraviolet rays, polyhydroxystyrenes can be preferably used particularly in exposure with KrF or ArF excimer laser light. The novolac resin has a large absorbance at the wavelength of the KrF excimer laser beam and the exposure intensity at the bottom portion of the resist film is weakened, so that the resist shape tends to be trapezoidal.
[0012]
When the phenolic hydroxyl group-containing alkali-soluble resin is a polyhydroxystyrene, specifically, o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 2- (o-hydroxyphenyl) propylene, 2- (m Resin obtained by polymerizing hydroxystyrenes such as -hydroxyphenyl) propylene and 2- (p-hydroxyphenyl) propylene alone or in the presence of a radical polymerization initiator, an anionic polymerization initiator or a cationic polymerization initiator It is done. Moreover, you may use what hydrogenated in order to reduce the light absorbency of resin after superposition | polymerization.
[0013]
Resins in which at least a part of the hydroxyl groups of these phenolic hydroxyl group-containing alkali-soluble resins are protected with an acid-decomposable protecting group can also be used.
As the acid-decomposable protecting group, any acid can be used as long as it is desorbed at room temperature or after heating (post-exposure bake) with an acid generated from component (C) during exposure to regenerate the phenolic hydroxyl group. Although not limited, for example, methoxymethoxy group, 1-methoxyethoxy group, 1-methoxypropyloxy group, 1-methoxybutyloxy group, 1-ethoxyethoxy group, 1-ethoxypropyloxy group, 1-ethoxybutyloxy group, 1 -(N-butoxy) ethoxy group, 1- (iso-butoxy) ethoxy group, 1- (sec-butoxy) ethoxy group, 1- (tert-butoxy) ethoxy group, 1- (cyclohexyloxy) ethoxy group, tetrahydrofuranyl Acetal groups such as oxy groups and tetrahydropyranyloxy groups

Ketal group such as 1-methoxy-1-methylethoxy group, methoxycarbonyloxy group, ethoxycarbonyloxy group, n-propyloxycarbonyloxy group, iso-propyloxycarbonyloxy group, n-butoxycarbonyloxy group, sec-butoxy Carbonyloxy group, iso-butoxycarbonyloxy group, t-butoxycarbonyloxy group, menthyloxycarbonyloxy group, etc.

In the present specification, the acid-decomposable protecting group represents an oxygen atom derived from a phenolic hydroxyl group. Among these, a group represented by the following general formula (I) is particularly preferable.
[0014]
[Chemical 2]

[0015]
(However, R ¹ And R ² Independently represents a hydrogen atom, an optionally substituted alkyl group or an optionally substituted alkoxy group; ^Three Represents an alkyl group which may be substituted. R ¹ And R ^Three And may be bonded to each other to form a ring. )
R ¹ ~ R ^Three The number of carbon atoms of the alkyl group and alkoxy group represented by is preferably 1-20, more preferably 1-10.
As the component (A), these may be used alone or a plurality of them may be mixed and used. In the resin in which the phenolic hydroxyl group is protected with an acid-decomposable protecting group, the acid-decomposable protecting group may be used alone or in a plurality of types, and a plurality of types may be used in one molecule of the resin. A copolymer having an acid-decomposable protecting group may be used.
[0016]
As the component (A), the difference in solubility between the exposed portion and the unexposed portion of the resist becomes larger when the resin in which the phenolic hydroxyl group is protected with an acid-decomposable protecting group is used. This is preferable because the resist shape and resolution are improved.
Although the protection rate of the phenolic hydroxyl group of the alkali-soluble resin by the acid-decomposable protecting group is not particularly limited, it is preferably 5 to 60%, particularly preferably 10 to 50%. When the protection ratio is too smaller than the above description, the remaining film ratio of the unexposed portion of the resist film is lowered, and the resolution tends to be lowered. On the other hand, if the protection ratio is too large, the developer may be repelled during development, and development may not be possible.
[0017]
The weight average molecular weight Mw of the resin used as the component (A) can be used as long as it is within a range in which a resist film can be formed and can be developed with an alkali developer after exposure, but is preferably a polystyrene equivalent value (gel permeation. Chromatographic measurement) is usually 3,000 to 100,000, preferably 4,000 to 50,000, more preferably 6,000 to 40,000.
If the weight average molecular weight of the resin is larger than this range, the solubility of the exposed portion in an alkaline developer is reduced, and a good resist pattern may not be obtained. Further, if the weight average molecular weight of the resin is smaller than this range, a good resist coating film may not be obtained.
[0018]
As a method for adjusting the phenolic hydroxyl group-containing alkali-soluble resin to the above range, there are a fractional precipitation method, a fractional dissolution method, a column fractionation method, an ultracentrifugation method, etc., but any method may be used. The molecular weight distribution Mw / Mn of the resin is preferably 1 or more and 1.5 or less from the viewpoint of resolving power.
Component (B) (hereinafter referred to as dissolution inhibitor) is added to the composition to lower the alkali dissolution rate of component (A) and improve the solubility of the resist film at room temperature or under heating after exposure. As long as the compound has a group that can be decomposed by the action of an acid to give alkali solubility, specifically, a structure capable of generating a hydroxyl group, it has the effect of improving dissolution contrast. Either an acetal structure or a carbonate structure is possible, but a carbonate structure is preferred, and particularly advantageous in combination with the case where the acid-decomposable protecting group of the resin (A) is an acetal group. is there. Specifically, alcohols such as ethanol, propanol, butanol, cyclohexanol, 1,4-cyclohexanediol, ethylene glycol, propylene glycol, glycerin, phenols such as phenol, cresol, resorcinol, pyrogallol, o-hydroxybenzophenone, m -Hydroxybenzophenone, p-hydroxybenzophenone, 4,4'-dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,3,4,2 ', 4 It is obtained by condensing hydroxybenzophenones such as' -pentahydroxybenzophenone or phenols and aldehydes or ketones as described in JP-A-6-51519. At least part of the hydroxyl group of the hydroxyl group-containing compound such as polynuclear phenols is methoxycarbonyloxy group, ethoxycarbonyloxy group, n-propyloxycarbonyloxy group, iso-propyloxycarbonyloxy group, n-butoxycarbonyloxy group, sec A carbonate group such as -butoxycarbonyloxy group, iso-butoxycarbonyloxy group, tert-butoxycarbonyloxy group, menthyloxycarbonyloxy group, more specifically, an alkoxycarbonyloxy group which may have a substituent. Protected compounds are mentioned. Carbon number of this alkoxy group is about 1-20 normally.
[0019]
Of these, compounds in which at least a part of hydroxyl groups of polynuclear phenols obtained by condensing phenols with aldehydes or ketones are protected with carbonate groups are preferred. More specifically, phenols mean 1 to 3 valent phenols which may have a substituent such as an alkyl group, and the aldehyde includes a substituent such as formaldehyde, acetaldehyde, an alkyl group and / or a hydroxyl group. C of benzaldehyde that may have ₁ ~ C ₁₅ Aliphatic aldehydes or aromatic aldehydes, and as ketones, C, such as acetophenone, which may have a substituent such as acetone, an alkyl group and / or a hydroxyl group _Three ~ C ₁₅ , Aliphatic or aromatic ketones. The component (B) is distinguished from the resin of the component (A). Therefore, the preferred molecular weight range is 200 or more and less than 3,000. If the molecular weight is smaller than this range, a sufficient dissolution inhibiting effect cannot be obtained. If the molecular weight is larger than this range, the solubility after exposure tends to decrease, and the resist pattern shape tends to deteriorate.
[0020]
In the case of a compound in which at least a part of hydroxyl groups of polynuclear phenols is protected with a carbonate group, the higher the protection rate of phenolic hydroxyl groups in one molecule, the higher the dissolution inhibiting effect. The following protection rates are preferred. More preferably, they are 60% or more and 100% or less, More preferably, they are 80% or more and 100% or less.
[0021]
The addition amount of the dissolution inhibitor is 1 to 50 parts by weight, preferably 5 to 40 parts by weight, based on 100 parts by weight of the resin component (A).
When the amount of the dissolution inhibitor is used within this range, a sufficient change in dissolution rate can be obtained between the exposed portion and the unexposed portion, and a particularly good resist pattern can be obtained. When there are too many dissolution inhibitors, the undecomposed dissolution inhibitor after exposure may not dissolve in the developer and a residue may remain between the resist patterns.
[0022]
The component (C) used in the present invention (hereinafter referred to as a photoacid generator) is not particularly limited as long as it generates an acid by actinic rays or radiation used for exposure, and is conventionally known. Specifically, for example, tris (trichloromethyl) -s-triazine, tris (tribromomethyl) -s-triazine, tris (dibromomethyl) -s-triazine, 2,4-bis (tribromo Halogen-containing s-triazine derivatives such as methyl) -6-p-methoxyphenyl-s-triazine, 1,2,3,4-tetrabromobutane, 1,1,2,2-tetrabromoethane, carbon tetrabromide , Halogen-substituted paraffinic hydrocarbons such as iodoform, hexabromocyclohexane, hexachlorocyclohexane, hexabromocyclodode Halogen-substituted cycloparaffinic hydrocarbons such as benzene, halogen-containing benzene derivatives such as bis (trichloromethyl) benzene, bis (tribromomethyl) benzene, tribromomethylphenylsulfone, trichloromethylphenylsulfone, 2,3-dibromosulfolane, etc. Halogen-containing sulfone compounds, halogen-containing isocyanurate derivatives such as tris (2,3-dibromopropyl) isocyanurate, triphenylsulfonium chloride, triphenylsulfonium methanesulfonate, triphenylsulfonium trifluoromethylsulfonate, triphenylsulfonium, p- Toluenesulfonate, triphenylsulfonium tetrafluoroborate, triphenylsulfonium hexafluoroarsenate, triphenyl Sulfonium salts such as rusulfonium hexafluorophosphonate, diphenyliodonium trifluoromethylsulfonate, diphenyliodonium p-toluenesulfonate, diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluoroarsenate, iodonium salts such as diphenyliodonium hexafluorophosphonate, p-toluene Methyl sulfonate, ethyl p-toluenesulfonate, butyl p-toluenesulfonate, phenyl p-toluenesulfonate, 1,2,3-tri (p-toluenesulfonyloxy) benzene, p-toluenesulfonic acid benzoin ester, methane Methyl sulfonate, ethyl methanesulfonate, butyl methanesulfonate, 1,2,3-tri (methanesulfonyloxy) Benzene, phenyl methanesulfonate, benzoin ester methanesulfonate, methyl trifluoromethanesulfonate, ethyl trifluoromethanesulfonate, butyl trifluoromethanesulfonate, 1,2,3-tri (trifluoromethanesulfonyloxy) benzene, trifluoromethanesulfonic acid Sulfonic esters such as phenyl, trifluoromethanesulfonic acid benzoin ester, disulfones such as diphenyldisulfone, carbonylsulfonyldiazomethanes such as phenylcarbonylphenylsulfonyldiazomethane, bis (phenylsulfonyl) methane, bis (cyclohexylsulfonyl) methane, etc. Bissulfonylmethanes, bis (phenylsulfonyl) diazomethane, bis (cyclohexylsulfonyl) dia Bissulfonyldiazomethanes such as methane, o-nitrobenzyl esters such as o-nitrobenzyl-p-toluenesulfonate, sulfone hydrazides such as N, N′-di (phenylsulfonyl) hydrazide, phthaliminotrifluoromethylsulfonate, Examples include iminosulfonates such as phthalimino p-toluenesulfonate and phthaliminocamphorsulfonate. Among these, compounds that generate sulfonic acid after exposure are preferably used, and bisphenylsulfonyldiazomethanes represented by the following general formula (II) are particularly preferable.
[0023]
[Chemical 3]

[0024]
(However, R ^Four , R ^Five Represents independently a linear, branched or cyclic alkyl group which may be substituted, an allyl group which may be substituted, or an aralkyl group which may be substituted. )
[0025]
In the radiation-sensitive composition of the present invention, the photoacid generator (C) is used in an amount of 0.001 to 30 parts by weight, preferably 0.05 to 20 parts by weight with respect to 100 parts by weight of the resin component (A). It is done.
If the amount of the photoacid generator is less than this range, the sensitivity is inferior, and if it is more than this range, the resist pattern becomes trapezoidal due to a decrease in the transparency of the resist film by the photoacid generator, which may cause a decrease in resolution. is there.
The organic carboxylic acid of component (D) is effective in suppressing a decrease in resist performance due to the invasion of a basic substance from the environment, and particularly when used in combination with a dissolution inhibitor (B), It is possible to realize better environmental resistance than conventionally known while maintaining resistance.
[0026]
Specific examples of organic carboxylic acids that can be used in the present invention include formic acid, acetic acid, propionic acid, n-butyric acid, iso-butyric acid, succinic acid, malonic acid, succinic acid, glutaric acid, adipic acid, acrylic acid, and methacrylic acid. , Aliphatic carboxylic acids such as maleic acid and fumaric acid, ketocarboxylic acids such as pyruvic acid, benzoic acid, salicylic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxy A structural unit of an aromatic carboxylic acid such as benzoic acid, 2,6-dihydroxybenzoic acid, phthalic acid, terephthalic acid, isophthalic acid or the like, or an aromatic carboxylic acid commercially available under the trade name SAX (manufactured by Mitsui Toatsu Chemicals) Including polymers can be used. The component (D) is added in an amount of 0.0001 to 10 parts by weight, preferably 0.001 to 5 parts by weight, based on 100 parts by weight of the component (A).
[0027]
When the component (D) is used in an amount within the above range, the effect of preventing the diffusion of the basic substance entering from the environment to the exposed portion can be obtained, and a good resist pattern can be obtained. However, an excessively large amount is not preferable because the remaining film ratio of the unexposed portion of the resist is lowered.
Additives can be added to the radiation sensitive resin composition of the present invention, and examples include organic bases, surfactants, and light absorbers.
The organic base prevents the acid generated from the photoacid generator from diffusing into the unexposed area, and specific examples thereof include alkylamines, arylamines, pyridines, pyridinium salts, and the like. The compounds disclosed in JP-A No. 127369, JP-A-5-232706, JP-A-7-92678, JP-A-9-179300, JP-A-9-32596, and the like can be used.
[0028]
The organic base is added in an amount of 0.0001 to 5 parts by weight, preferably 0.001 to 2 parts by weight, based on 100 parts by weight of the component (A) resin.
When the organic base is used in an amount within the above range, an effect of preventing sufficient diffusion of the acid to the unexposed area can be obtained, and a good resist pattern can be obtained. However, an excessive amount is not preferable because the sensitivity of the resist is lowered.
[0029]
The surfactant is added for the purpose of improving the coating properties of the radiation-sensitive resin composition, improving the film thickness uniformity during spin coating, and improving the developability of the radiation-sensitive resin composition.
Surfactants that can be used for such purposes include, for example, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene glycol Laurate, polyoxyethylene glycol distearate, F-top EF301, EF303, EF352 (manufactured by Tochem Products), MegaFuck F170, F171, F172, F173 (manufactured by Dainippon Ink), Fluorard FC430, FC431, FC170C ( Manufactured by Sumitomo 3M), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC- 06 (manufactured by Asahi Glass Co., Ltd.), (manufactured by Shin-Etsu Chemical Co., Ltd.) KP341, Polyflow No. 75, no. 95 (manufactured by Kyoeisha Yushi Chemical Co., Ltd.).
[0030]
These surfactants can be used alone or in admixture of two or more, and are usually used in a proportion of 0.01 to 3 parts by weight of the surfactant with respect to 100 parts by weight of the resin component (A). Is done.
In the case of forming a resist image on a substrate having a high reflectance such as aluminum, a light absorbing agent can be added in order to prevent deterioration of the resist pattern shape due to reflection of exposure light from the substrate. Examples of the light absorber used for such purposes include naphthoquinone diazide compounds, benzophenones, and condensed aromatic ring-containing compounds such as naphthalene and anthracene.
[0031]
The radiation-sensitive resin composition of the present invention is used by dissolving the above components in an appropriate solvent. The solvent is not particularly limited as long as it is a solvent that has sufficient solubility and good coating properties with respect to each component of the present invention and other additives, but ketone solvents such as 2-hexanone and cyclohexanone. Cellosolve solvents such as methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, diethyl oxalate, ethyl pyruvate, ethyl-2-hydroxybutyrate, ethyl acetoacetate, butyl acetate, amyl acetate, ethyl butyrate, butyric acid Ester solvents such as butyl, methyl lactate, ethyl lactate, methyl 3-methoxypropionate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether Propylene glycol solvents such as rubacetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol dimethyl ether, ketone solvents such as cyclohexanone, methyl amyl ketone, 2-heptanone, or a mixed solvent thereof, or further The thing etc. which added the aromatic hydrocarbon are mentioned. The use ratio of the solvent is preferably in the range of 1 to 20 times as a weight ratio with respect to the total amount of solid content in the radiation-sensitive resin composition.
[0032]
When a resist pattern is formed on a semiconductor substrate using the radiation-sensitive resin composition of the present invention, the radiation-sensitive resin composition of the present invention dissolved in a solvent as described above is usually applied onto the semiconductor substrate. , Pre-baking, pattern transfer by exposure, post-exposure heating (post-exposure baking; PEB), and development, and can be used as a photoresist. The semiconductor substrate is usually used as a substrate for manufacturing a semiconductor, and is a silicon substrate, a gallium arsenide substrate, or the like.
[0033]
A spin coater is usually used for coating, and light exposure of 157 nm, 193 nm, 222 nm, 248 nm light, X-rays, electrons using a high pressure mercury lamp 436 nm, 365 nm light, a low pressure mercury lamp 254 nm, or an excimer laser as a light source. A line or the like is preferably used. The light at the time of exposure may be broad instead of monochromatic light. Further, exposure by super-resolution exposure techniques such as phase shift method and annular illumination can also be applied.
[0034]
The developer of the radiation sensitive resin composition of the present invention includes inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine and the like. Primary amines, secondary amines such as diethylamine and di-n-propylamine, tertiary amines such as triethylamine, N, N-diethylmethylamine, tetramethylammonium hydroxide, trimethylhydroxyethylammonium hydro A quaternary ammonium salt such as an oxide, or a compound obtained by adding an alcohol, a surfactant or the like to this can be used.
[0035]
The radiation-sensitive resin composition of the present invention is useful not only for the production of VLSI, but also for general IC production, mask production, image formation, liquid crystal screen production, color filter production or offset printing. In particular, it is useful for KrF excimer laser exposure.
[0036]
【Example】
EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention will not receive any restriction | limiting by an Example, unless the summary is exceeded.
Synthesis Example 1 (Synthesis of 1-ethoxyethylated polyhydroxystyrene)
A 1 L four-necked flask equipped with a nitrogen inlet tube, a stirrer, and a thermometer was charged with 30 g of polyhydroxystyrene (manufactured by Nippon Soda Co., Ltd., weight average molecular weight 15,900, Mw / Mn 1.12) and 1,3-dioxolane. After adding 300 mL and dissolving uniformly, 15.0 g of ethyl vinyl ether was added, and it heated at 40 degreeC with the water bath. To this, 0.3 g of 36% hydrochloric acid was added and stirring was continued for 4 hours. After the reaction, 3 mL of 28% aqueous ammonia was added to the reaction solution and stirred for 30 minutes. This reaction solution was dropped into 3 L of pure water, and the resulting precipitate was filtered. Furthermore, the target polymer was recovered by dissolving the precipitate in acetone and dropping the solution into pure water for precipitation. The precipitated polymer was vacuum-dried to obtain 37.1 g of 1-ethoxyethylated polyvinylphenol.
When the obtained polymer was dissolved in deuterated acetone and the proton NMR spectrum was measured, a signal of aromatic hydrogen having a δ value of 6.2 to 7.0 and an acetal methine hydrogen having a δ value of 5.2 to 5.5 were obtained. The ratio of the area to the signal was 10.2: 1. From this result, the acetalization rate was calculated to be 39.4%.
[0037]
Synthesis Example 2 (Synthesis of dissolution inhibitor 1)
In a 300 mL four-necked flask equipped with a nitrogen inlet tube, a stirrer, and a thermometer, the following structural formula (III)
[0038]
[Formula 4]

[0039]
After adding 4.28 g of a compound represented by the formula (Bis-RS3P, manufactured by Honshu Chemical Co., Ltd.) and 20 mL of 1,3-dioxolane and dissolving uniformly, 5.47 g of menthyl chloroformate was added, and water bath was added. To 40 ° C. To this, a solution of 2.53 g of triethylamine in 5 mL of 1,3-dioxolane was added dropwise over 5 minutes, and stirring was continued for 3 hours after completion of the addition. After the reaction, a precipitate obtained by dropping the reaction solution into 400 mL of pure water was filtered. Further, the precipitate was dissolved in acetone, and the solution was dropped into pure water to precipitate, thereby recovering the target product having a menthyl carbonate group. The precipitated solid was vacuum-dried to obtain 4.89 g of dissolution inhibitor 1.
[0040]
The obtained dissolution inhibitor 1 was dissolved in deuterated acetone, and the proton NMR spectrum was measured. The area ratio with the signal of methine hydrogen was 2.74: 1. From this result, the protection rate of the phenolic hydroxyl group by the menthyl carbonate group was calculated to be 94.9%.
[0041]
Synthesis Example 3 (Synthesis of dissolution inhibitor 2)
To a 300 mL four-necked flask equipped with a nitrogen inlet tube, a stirrer, and a thermometer, 4.28 g of the compound represented by the structural formula (III) (Bis-RS3P, manufactured by Honshu Chemical Co., Ltd.) and 30 mL of acetone were added. Further, after uniformly dissolving, 0.05 g of N, N-dimethylaminopyridine was added and heated to 40 ° C. in a water bath. To this, 11.0 g of di (tert-butyl) dicarbonate was added dropwise over 10 minutes, and stirring was continued for 4 hours after completion of the addition. After the reaction, this reaction solution was dropped into 1 L of pure water, and the resulting precipitate was filtered. Further, this precipitate was dissolved in acetone, and the solution was dropped into pure water and precipitated to recover the target product. The precipitated solid was vacuum-dried to obtain 9.02 g of dissolution inhibitor 2.
[0042]
The obtained dissolution inhibitor was dissolved in deuterated acetone, and proton NMR spectrum was measured. As a result, an aromatic hydrogen signal having a δ value of 7.0 to 7.4 and a tert value having a δ value of 1.3 to 1.7 were obtained. -The area ratio with the signal of butyl group hydrogen was 1.96: 6.74. From this result, when the protection rate of the phenolic hydroxyl group by the tert-butyl carbonate group was determined, it was 99.3%.
[0043]
Synthesis Example 4 (Synthesis of photoacid generator)
(1) After adding 12.1 g of paraformaldehyde and 60 g of toluene to a 1 L four-necked flask equipped with a nitrogen introduction tube, a stirrer, and a thermometer and stirring, 120 mL of concentrated hydrochloric acid was added and heated to 40 ° C. in a water bath. To this, 60 g of a toluene solution of 35.4 g of cyclohexanethiol was added dropwise over 20 minutes. After completion of the dropwise addition, the reaction solution was stirred while maintaining at 50 ° C. After confirming the completion of the reaction by TLC, the aqueous layer was discarded and made alkaline with a saturated sodium carbonate aqueous solution to obtain a toluene solution of chloromethylcyclohexyl sulfide.
(2) 7.4 g of 4-methoxybenzenethiol was placed in a 200 mL flask, and 45.2 g of a 5 wt% ethanol solution of sodium hydroxide was added and stirred. While this flask was cooled with water, 27.8 g of a toluene solution of chloromethylcyclohexyl sulfide obtained in (1) was added dropwise over 5 minutes. After stirring for 2 hours, the temperature was raised to 70 ° C., and the mixture was further stirred for 1 hour. After adding 500 mg of sodium tungstate to this reaction solution, 25 g of 30% aqueous hydrogen peroxide was added over 1 hour and stirred for 5 hours. After extraction with toluene and drying over anhydrous sodium sulfate, the solvent was distilled off under reduced pressure to obtain cyclohexylsulfonyl- (4-methoxyphenylsulfonyl) methane.
(3) Cyclohexylsulfonylhexylsulfonyl- (4-methoxyphenylsulfonyl) methane (3.0 g) synthesized in (2) was placed in a flask, and ethanol (100 mL) was added and stirred. Further, 8.0 g of 5 wt% ethanol solution of sodium hydroxide was added to this solution and stirred. The reaction solution was cooled from −5 ° C. to −10 ° C. and 35 mL of pure water was added. Then, 10 mL of ethanol solution of 2.0 g of p-toluenesulfonyl azide was added dropwise over 5 minutes, and the mixture was stirred for 3 hours and allowed to stand. After standing overnight, the precipitate was collected by filtration to obtain crude crystals. This crude crystal was recrystallized from ethanol to obtain cyclohexylsulfonyl- (4-methoxyphenylsulfonyl) diazomethane.
[0044]
Example 1
0.60 g of resin synthesized in Synthesis Example 1, 0.06 g of dissolution inhibitor 1 synthesized in Synthesis Example 2, 0.012 g of photoacid generator synthesized in Synthesis Example 4, 0.0023 g of salicylic acid as an organic carboxylic acid, additive As bis (2-hydroxyethyl) iminotris (hydroxymethyl) methane 0.0011 g represented by the following structural formula (IV):
[0045]
[Chemical formula 5]

[0046]
0.0004 g of Fluorad FC430 (manufactured by Sumitomo 3M) as a surfactant and 3.15 g of propylene glycol monomethyl ether acetate and 0.65 g of ethyl lactate as a solvent were mixed to obtain a resist photosensitive solution. As a basic substrate, a substrate in which poly (N-phenylmaleimide) is applied to a silicon substrate with a film thickness of 800 nm is prepared, a resist photosensitive solution is spin-coated on this substrate, and then heated at 90 ° C. for 60 seconds on a hot plate. Baking was performed to obtain a resist film having a thickness of 0.72 μm. Furthermore, in order to evaluate the resistance to an acidic protective film, polyvinyl pyrrolidone and perfluorooctyl sulfonic acid are dissolved in pure water so that the solid content concentration is 2.5 wt% and the pH is 2.0. The resulting aqueous solution was spin-coated to a thickness of 40 nm and baked at 60 ° C. for 60 seconds. The resist film was exposed using a Nikon KrF excimer laser reduced projection exposure apparatus (NA = 0.42) and then baked on a hot plate at 110 ° C. for 60 seconds. Thereafter, the resist film was developed with a 2.38% by weight aqueous solution of tetramethylammonium hydroxide for 1 minute. By observing the resist pattern obtained after the development with a scanning electron microscope, the resolution, pattern shape, surface roughness of the resist film, and tailing of the resist near the substrate were evaluated.
[0047]
The exposure amount at which 0.30 μm line and space is resolved with a line width of 0.30 μm is defined as the optimum exposure sensitivity, and the minimum resolution dimension in the line and space pattern at this time is defined as the resolving power. Further, the surface roughness of the resist film was evaluated by observing a 0.30 μm line-and-space resist film surface with an optimum exposure sensitivity with a scanning electron microscope. Similarly, for resist skirting near the substrate, a 0.30 μm line-and-space resist cross-sectional shape at the optimum exposure sensitivity is observed with a scanning electron microscope. (5: None at all, 4: Almost none, 3: Existence (defect), 2: Existence (defect), 1: Remarkable (defect)).
The results are shown in Table-1.
[0048]
Example 2
Except that the dissolution inhibitor was changed to the dissolution inhibitor 2 of Synthesis Example 3, the resist resolution, pattern shape, resist film surface roughness, and resist tailing in the vicinity of the substrate were evaluated in the same manner as in Example 1.
The results are shown in Table-1.
[0049]
Comparative Example 1
Except that salicylic acid as an organic carboxylic acid component was not added, the resist resolving power, pattern shape, resist film surface roughness, and resist tailing in the vicinity of the substrate were evaluated in the same manner as in Example 1.
The results are shown in Table-1.
[0050]
Comparative Example 2
Except that salicylic acid as an organic carboxylic acid component was not added, the resist resolving power, pattern shape, resist film surface roughness, and resist tailing in the vicinity of the substrate were evaluated in the same manner as in Example 2.
The results are shown in Table-1.
[0051]
Comparative Example 3
Except that the dissolution inhibitor 1 was not added, the resist resolving power, pattern shape, resist film surface roughness, and resist tailing in the vicinity of the substrate were evaluated in the same manner as in Example 1.
The results are shown in Table-1.
[0052]
[Chemical 6]

[0053]
[Table 1]

[0054]
【The invention's effect】
The radiation sensitive resin composition of the present invention maintains a good sensitivity and resolution by using the above components (B) and (D) together in the chemically amplified positive radiation sensitive resin composition, In addition, it is possible to form a resist pattern having a good shape that is excellent in environmental resistance such as a substrate and an upper protective film, and does not have film alignment or tailing.

Claims (6)

(A) a phenolic hydroxyl group-containing alkali-soluble resin or a resin in which at least a part of the hydroxyl group is protected with an acid-decomposable protecting group, (B) a moiety capable of generating a group that decomposes by the action of an acid and imparts alkali solubility. A positive radiation sensitive resin composition comprising a compound having a structure and (C) a compound capable of decomposing by actinic rays or radiation to generate an acid, further comprising (D) an organic carboxylic acid , and a component ( A positive radiation-sensitive resin composition having a molecular weight of B) of 200 or more and less than 3,000 .   2. The positive radiation-sensitive resin composition according to claim 1, wherein the component (A) is a resin in which at least a part of the phenolic hydroxyl group is protected with an acid-decomposable protecting group. The positive radiation sensitive resin composition according to claim 1 or 2, wherein the acid-decomposable protecting group of the component (A) has a structure represented by the following general formula (I).

(However, R ¹ and R ² independently represent a hydrogen atom, an optionally substituted alkyl group or an optionally substituted alkoxy group, and R ³ represents an optionally substituted alkyl group. R ¹ and R ³ may be bonded to each other to form a ring.)   The positive radiation sensitive composition according to claim 3, wherein the component (A) is a resin in which at least a part of the phenolic hydroxyl group of the polyhydroxystyrene is protected with an acid-decomposable protecting group represented by the general formula (I). Resin composition. The positive radiation sensitive resin composition according to any one of claims 1 to 4 , wherein the partial structure of the component (B) is a carbonate structure. The positive radiation sensitive resin composition according to any one of claims 1 to 5 , wherein the component (B) is a compound in which at least a part of the phenolic hydroxyl group of the polynuclear phenol is substituted with a carbonate structure.