JP3766245B2 - Pattern forming method and semiconductor device manufacturing method - Google Patents

Description

【００１７】
ここで、上記化学式（１）において、Ｒ¹，Ｒ²は水素原子またはメチル基であり、ｘ，ｙはそれぞれｘ＋ｙ＝１，０＜ｘ≦１，０≦ｙ＜１を満たす任意の数であり、重合体の重量平均分子量は１，０００〜５００，０００とする。
【００１８】
上記化学式（１）で示される繰り返し単位を有する重合体は、高いドライエッチング耐性が得られることが知られている脂環族構造を側鎖に有しており、かつ２個以上共役した不飽和結合を有していないことから、１９３nmを含む遠紫外領域で透明である。すなわち、本発明の感放射線組成物は高いドライエッチ耐性と１９３nmを含む遠紫外領域での透明性を兼ね備えている。
【００１９】
また、上記化学式（１）で示される繰り返し単位を有する重合体の有するδ−ヒドロキシカルボン酸構造は、カルボン酸のエステル化の相手となるアルコールが分子内のカルボン酸のδ位に存在することから、酸触媒反応によるエステル化が通常よりも容易に起こり易い。また、カルボン酸と水酸基が同一の環構造に含まれることから、両者は立体的に近づきやすく、エステル化が容易に起こり易い。そのため、高感度でパタン形成ができる。この反応は分子内のエステル化であるので、分子間の架橋等も起きず、単純にカルボン酸の量が露光部と未露光部で変化する。また生成したエステルは、通常用いられているテトラアルキルアンモニウムヒドロキシド水溶液では加水分解されず、現像中も安定である。そのため、溶解速度が大きく変化し、膨潤が避けられ、良好な微細パタンを形成できる。
【００２０】
なお、酸触媒反応を起こすための酸は、活性放射線の照射により酸を発生する酸発生剤を用いることにより実現される。
【００２１】
また、上記化学式（１）（Ｒ¹は水素原子またはメチル基）で示される繰り返し単位を有する重合体は、化学式（３）で示される繰り返し単位を有する重合体のδ−ラクトン環構造の一部、または全てを加水分解反応により、δ−ヒドロキシカルボン酸構造とすることで得られる。
【００２２】
【化４】

【００２３】
この加水分解反応における反応条件を選定することにより、重合体中のδ−ヒドロキシカルボン酸構造と、δ−ラクトン構造の割合を任意に制御することができる。その結果、現像液に対する溶解速度の制御およびレジストの高感度化が可能となる。なお、重合体中のδ−ヒドロキシカルボン酸構造の割合は、その膜形成成分が用いる現像液に可溶になる割合以上であればよい。
【００２４】
上記化学式（３）で示される繰り返し単位を有する重合体は、化学式（４）（Ｒ¹は水素原子またはメチル基）で示されるアクリル酸エステルまたはメタクリル酸エステルをラジカル重合し、さらに過酢酸でケトン構造をδ−ラクトン構造に酸化することによって容易に誘導可能である。
【００２５】
【化５】

【００２６】
この時、上記アクリル酸エステルとメタクリル酸エステルとからなる共重合体を用いてもよい。共重合体中のアクリル酸エステルとメタクリル酸エステルの割合を任意に選定することで、現像液に対する溶解速度の制御が可能となる。上記アクリル酸エステルまたはメタクリル酸エステルは、アクリル酸またはメタクリル酸を（エピ）アンドロステロンでエステル化することにより容易に得られる。
【００２７】
また、上記重合体が、化学式（２）で示されるような、つまり、化学式（１）で示される繰り返し単位に、さらに、共役した不飽和結合を持たない脂環基単位を組み合わせた重合体を特徴とする感放射線組成物も本発明において非常に有効である。
【００２８】
【化６】

【００２９】
ここで、上記化学式（２）において、Ｒ¹，Ｒ²，Ｒ³は水素原子またはメチル基、Ｒ⁴は少なくとも共役した不飽和結合を持たない脂環族構造であり、ｘ，ｙ，ｚはそれぞれｘ＋ｙ＋ｚ＝１，０＜ｘ≦１，０≦ｙ＜１，０＜ｚ＜１を満たす任意の数であり、重合体の重量平均分子量は１，０００〜５００，０００とする。
【００３０】
上記化学式（２）において、Ｒ⁴で示される共役した不飽和結合を持たない脂環基としては、シクロヘキシル基、トリシクロ〔５．２．１．０〕デシル基、アダマンチル基、ノルボルニル基、β−コレスタノール基、コレステロール基等が挙げられるが、これらに限定されるものではない。
【００３１】
上記化学式（２）で示される繰り返し単位を有する重合体は、高いドライエッチ耐性と１９３nmを含む遠紫外領域での透明性を兼ね備えている。また、化学式（２）で示される繰り返し単位を有する重合体の有するδ−ヒドロキシカルボン酸構造は、エステル化が容易に起こり易く、高感度でパタン形成ができる可能性がある。また、この反応は分子内のエステル化であるので、分子間の架橋等も起きず、膨潤が避けられ、微細パタンが形成できる。また生成したエステルは、通常用いられているテトラアルキルアンモニウムヒドロキシド水溶液では加水分解されず、現像中も安定である。
【００３２】
この重合体は、化学式（５）で示される繰り返し単位を有する重合体のδ−ラクトン環構造の一部、または全てを加水分解反応により、δ−ヒドロキシカルボン酸構造とすることで得られる。
【００３３】
【化７】

【００３４】
ここで、化学式（５）において、Ｒ¹，Ｒ²は水素原子またはメチル基、Ｒ⁴は少なくとも共役した不飽和結合を持たない脂環族構造であり、ｘ，ｙはそれぞれｘ＋ｙ＝１，０＜ｘ＜１，０＜ｙ＜１を満たす任意の数である。
【００３５】
上記化学式（５）で示される繰り返し単位を有する重合体は、前記化学式（４）で示されるアクリル酸エステルまたはメタクリル酸エステルと化学式（６）で示されるアクリル酸エステルまたはメタクリル酸エステルとを共重合し、さらに過酢酸で酸化することによって得られる。
【００３６】
【化８】

【００３７】
ここで、上記化学式（６）において、Ｒ¹は水素原子またはメチル基、Ｒ⁴は少なくとも共役した不飽和結合を持たない脂環族構造である。
【００３８】
共重合体の原料であるモノマーの仕込み割合、その他の重合条件を選定することで、容易に化学式（５）で示される繰り返し単位を有する重合体中のδ−ラクトン構造と脂環基構造の割合を任意に制御できる。さらに、加水分解反応における反応条件を選定することにより、化学式（２）で示される繰り返し単位を有する重合体中のδ−ヒドロキシカルボン酸構造、δ−ラクトン構造および脂環基構造の割合を任意に制御することが可能である。その結果、現像液に対する溶解速度の制御およびレジストの高感度化が可能となり、同時に、かさ高く疎水的な脂環基構造の導入により、現像液の浸潤による膨潤の抑制、酸の拡散制御もできる。なお、重合体中のδ−ヒドロキシカルボン酸構造の割合は、その膜形成成分が用いる現像液に可溶になる割合以上であればよい。
【００３９】
また、本発明の感放射線組成物中の重合体の重量平均分子量は１，０００〜５００，０００が好ましく、より好ましくは１，０００〜３０，０００である。また、上記重合体に対して、酸発生剤は、０．１重量部から５０重量部用いるのが望ましく、０．５重量部から２０重量部用いることがより望ましい。
【００４０】
上記酸発生剤としては、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ノナフレート、ジメチルフェニルスルホニウムトリフレート、ジメチル−４−ヒドロキシナフチルトリフレート等のオニウム塩、Ｎ−トリフルオロメタンスルホニルオキシナフチルイミド、Ｎ−メタンスルホニルオキシナフチルイミド、Ｎ−トリフルオロメタンスルホニルオキシスクシイミド、Ｎ−パーフルオロオクタンスルホニルオキシスクシイミド等のスルホニルオキシイミド、さらには、スルホン酸エステル等が挙げられるが、活性放射線、例えばＡｒＦエキシマレーザ等の照射により酸を発生するものであればよく、これらに限定されるものではない。また、これらの酸発生剤は、２種類以上を同時に用いてもよい。
【００４１】
また、本発明の感放射線組成物には、解像性向上やプロセス安定性および保存安定性向上のための、２−ベンジルピリジン、トリペンチルアミン、トリエタノールアミンなどの塩基性化合物や、ヨウ化テトラメチルアンモニウム、塩化テトラペンチルアンモニウム、ヨウ化テトラエチルホスホニウム等の塩を添加してもよい。これら塩基性化合物や塩は、用いる酸発生剤１００重量部に対して、０．０１重量部から１００重量部を添加することが望ましい。
【００４２】
また本発明の感光性組成物には、形成したパタンの耐熱性を高めるために、架橋剤としてヘキサメトキシメチルメラミン、１，３，４，６−テトラキス（メトキシメチル）グルコルウリル、１，４−ジオキサン−２，３−ジオールなどを含有させることができる。これらの架橋剤は、感光性組成物の膜形成成分１００重量部に対して、０．１重量部から５０重量部用いるのが望ましい。
【００４３】
また、本発明の感光性組成物には、現像液に対する溶解性の制御、解像性向上のために、カルボン酸を有する低分子化合物として、コール酸、アビエチン酸、（エピ）アンドロステロンから誘導可能な化学式（７）で示される化合物、または上記化合物が複数個結合したオリゴマー等を含有させることができる。これらの低分子化合物は、感光性組成物の膜形成成分１００重量部に対して、１重量部から、５０重量部用いるのが望ましい。
【００４４】
【化９】

【００４５】
なお本発明の感光性組成物は、溶液として基板に回転塗布して用いられる。この際用いる溶媒としては、上記の構成成分が十分に溶解し、かつ回転塗布で均一な塗布膜が形成可能な溶媒であれば、いかなる溶媒でもよい。また単独でも２種類以上を混合して用いてもよい。
【００４６】
本発明のパタン形成方法は、上記記載のいずれかの感放射線組成物からなる塗膜を、所定の基板上に形成する工程と、その塗膜に所定のパタンの活性化学線を照射する工程、活性放射線の照射後に基板を加熱する工程、基板の加熱後に塗膜をアルカリ水溶液にさらして活性放射線の未照射部を除去する工程を含むものである。
【００４７】
本発明で用いる活性放射線は、２５０nm以下の遠紫外光、ＡｒＦエキシマレーザ光のような真空紫外光が挙げられる。なお電子線、ＥＵＶ、エックス線等も用いることができる。本発明で所定のパタンの活性放射線を照射する際は、通常ＡｒＦエキシマレーザ光のような真空紫外光をマスクやレチクルを介して所定のパタン状にする。この際、変形照明法や位相シフトマスクに代表される超解像技術を用いた場合に、より高解像性のパタンが得られるので望ましい。
【００４８】
本発明で用いるアルカリ現像液は、炭素数１から５のテトラアルキルアンモニウムヒドロキシド水溶液であることが望ましい。
【００４９】
本発明の半導体装置の製造方法は、半導体基板上に上記記載のいずれかのパタン形成方法によりレジストパタンを形成し、それをもとに、基板をエッチング加工する工程か、もしくは基板にイオンを打ち込む工程を含むようにしたものである。
【００５０】
本発明の半導体の製造方法で用いられるエッチング加工法としては、プラズマエッチング、反応性イオンエッチング、反応性イオンビームエッチング等のドライエッチング法や、ウエットエッチング法が挙げられる。
【００５１】
本発明の半導体装置の製造方法において加工される基板としては、単結晶シリコンなどの表面にＣＶＤ法や熱酸化法で形成された二酸化珪素膜、塗布性ガラス膜などの酸化膜、あるいは窒化珪素膜等の窒化膜が挙げられる。またアルミニウムやその合金、タングステンなどの各種金属膜、多結晶シリコン等が挙げられる。
【００５２】
本発明の半導体装置の製造方法において作られる素子、特にメモリ素子は、微細なパタン形成が可能であることから、その集積度を上げることができる。したがって、素子を小さく作ることができるため、１枚のウェハから取れる素子の数が増えて、歩留まりが向上する。
【００５３】
【発明の実施の形態】
以下、本発明を実施例に基づいて、さらに詳細に説明するが、本発明はこれらに限定されるものではない。まず実施例に先立ち、本発明で用いた材料の合成例を示す。
【００５４】
（合成例１）モノマー（１ａ）の合成
アンドロステロン５．０ｇとピリジン１．５ｇをテトラヒドロフラン（ＴＨＦ）２００ｍｌに溶解し、これにアクリル酸クロリド１．６ｇをテトラヒドロフラン３０ｍｌに溶解した溶液を０℃で滴下した。滴下後、さらに室温で数時間攪拌し、沈殿したトリエチルアミン塩酸塩を濾別した。この濾液に酢酸エチル１５０ｍｌを加え、水１００ｍｌで４回水洗した後、有機層を無水硫酸ナトリウムで乾燥し、減圧下におくことで溶媒を取り除くと、残分が結晶化した。これをエタノール／テトラヒドロフラン混合溶媒から再結晶を行い、化学式（８）で示す白色の化合物モノマー（１ａ）を得た。
【００５５】
【化１０】

【００５６】
（合成例２）重合体（２ｃ−１）の合成
合成例１で得たモノマー（１ａ）４．０ｇをＴＨＦ４０ｍｌに溶解し、反応開始剤として２，２’−アゾビス（イソブチロニトリル）０．１９ｇを加え、７０℃で加熱還流して、６時間重合を行った。重合後、ｎ−ヘキサン５００ｍｌに溶液を注ぎ、ポリマーを析出させ、これを乾燥して化学式（９）で示す重合体（２ａ）を得た。
【００５７】
【化１１】

【００５８】
ゲルパーミエーションクロマトグラフィー（ＧＰＣ）により、テトラヒドロフラン中でこのポリマーのポリスチレン換算の分子量を調べたところ、重量平均分子量が２，８００、数平均分子量が２，３００であった。
【００５９】
上記のように合成したポリマー（２ａ）３．０ｇをテトラヒドロフラン１００ｍｌに溶解し、そこに酢酸１００ｍｌと過酸化水素水５０ｍｌを加え、５０℃で数時間撹拌した。反応後、溶媒を減圧留去して減らし、５００ｍｌの水の中に注いだ。沈殿物を濾別、乾燥して、化学式（１０）で与えられるδ−ラクトン構造を有する重合体（２ｂ）を得た。
【００６０】
【化１２】

【００６１】
上記のように合成したポリマー（２ｂ）２．５ｇをテトラヒドロフラン１００ｍｌに溶解し、０．５Ｎ水酸化ナトリウム水溶液１５０ｍｌを加え、２時間撹拌した。それに塩酸水溶液を徐々に加えて弱酸性にした。この溶液に酢酸エチル約１５０ｍｌを加えて抽出を２回行い、得られた有機層を１００ｍｌの水で２回洗浄し、有機層を無水硫酸ナトリウムで乾燥した。その後溶媒を減圧留去して減らし、ｎ−ヘキサン３００ｍｌへ注いでポリマーを析出させ、これを乾燥して白色粉末状のポリマー（２ｃ−１）を得た。得られたポリマーの構造は、種々の分析法によって、化学式（１１）の構造が主であることがわかった。
【００６２】
【化１３】

【００６３】
得られたポリマー（２ｃ−１）１００重量部を１−メトキシ−２−プロパノール１０００重量部に溶解し、孔径０．２μmのフィルタで濾過した。それをシリコン基板上に回転塗布し、１００℃で２分間ベークして薄膜を得た。
【００６４】
上記塗布膜（３００nm）をテトラメチルアンモニウムヒドロキシド水溶液（濃度０．１１３重量％）に浸したところ、干渉色が変化しながら５秒間で溶け、残膜が０になった。また、上記溶液をフッ化リチウム基板上に塗布した膜の吸収スペクトルを、真空紫外分光装置（ＡＲＣ社製）で測定したところ、膜厚１．０μmで波長１９３nmの遠紫外光に対する吸光度が０．２５であり、吸収が小さいことがわかった。
【００６５】
（合成例３）重合体（２ｃ−２）の合成
合成例２で合成したδ−ラクトン構造を有する重合体（２ｂ）２．５ｇをテトラヒドロフラン１００ｍｌに溶解し、合成例２での加水分解反応より穏やかな反応条件（水酸化ナトリウム水溶液濃度を０．２Ｎとし、撹拌時間を１５分間とした）で加水分解反応を行った。それに塩酸水溶液を徐々に加えて弱酸性にした。この溶液に酢酸エチル約１５０ｍｌを加えて抽出を２回行い、得られた有機層を１００ｍｌの水で２回洗浄した。洗浄後、有機層を無水硫酸ナトリウムで乾燥し、その後溶媒を減圧留去して減らし、ｎ−ヘキサン３００ｍｌへ注ぎ、ポリマーを析出させ、これを乾燥して白色粉末状のポリマー（２ｃ−２）を得た。得られたポリマーは、種々の分析法によって、重合体（２ｃ−１）より重合体中のδ−ヒドロキシカルボン酸構造の割合が少なく、化学式（１２）の構造が主であることがわかった。
【００６６】
【化１４】

【００６７】
得られたポリマー（２ｃ−２）１００重量部を１−メトキシ−２−プロパノール１０００重量部に溶解し、孔径０．２μmのフィルタで濾過した。それをシリコン基板に回転塗布し、１００℃で２分間ベークして薄膜を得た。
【００６８】
シリコン基板上に塗布した膜（３００nm）をテトラメチルアンモニウムヒドロキシド水溶液（濃度０．１１３重量％）に浸したところ、干渉色が変化しながら、１５秒間で溶け、残膜が０になった。また、上記溶液をフッ化リチウム基板上に塗布した膜の吸収スペクトルを、真空紫外分光装置で測定したところ、膜厚１．０μmで波長１９３nmの遠紫外光に対する吸光度が、０．２５であり、吸収が小さいことがわかった。
【００６９】
（合成例４）モノマー（３ａ）の合成
アンドロステロン５．０ｇとピリジン１．５ｇをテトラヒドロフラン２００ｍｌに溶解し、これにメタクリル酸クロリド１．７ｇをテトラヒドロフラン３０ｍｌに溶解した溶液を０℃で滴下した。滴下後、さらに室温で数時間攪拌し、沈殿したトリエチルアミンの塩酸塩を濾別した。濾液に酢酸エチル１５０ｍｌを加え、水１００ｍｌで４回水洗した後、有機層を無水硫酸ナトリウムで乾燥し、減圧下におくことで溶媒を取り除くと、残分が結晶化した。これをエタノール／テトラヒドロフラン混合溶媒から再結晶を行い、化学式（１３）で示す白色の化合物（３ａ）を得た。
【００７０】
【化１５】

【００７１】
（合成例５）重合体（４ｃ）の合成
合成例４で得たモノマー（３ａ）４．０ｇをＴＨＦ４０ｍｌに溶解し、反応開始剤として２，２’−アゾビス（イソブチロニトリル）０．１８ｇを加え、７０℃で加熱還流して、６時間重合を行った。重合後、ｎ−ヘキサン５００ｍｌに溶液を注いでポリマーを析出させ、これを乾燥して化学式（１４）で示す重合体（４ａ）を得た。
【００７２】
【化１６】

【００７３】
ゲルパーミエーションクロマトグラフィーにより、テトラヒドロフラン中でこのポリマーのポリスチレン換算の分子量を調べたところ、重量平均分子量が２６，０００、数平均分子量が２０，０００であった。
【００７４】
上記のように合成したポリマー（４ａ）を、合成例２と同様に、過酢酸による酸化を行い、化学式（１５）で示すδ−ラクトン構造を有する重合体（４ｂ）を得た。
【００７５】
【化１７】

【００７６】
上記のように合成したポリマー（４ｂ）を、合成例２と同様に、水酸化ナトリウム水溶液により加水分解を行い、δ−ヒドロキシカルボン酸を有する重合体（４ｃ）を得た。得られたポリマーの構造は、種々の分析法から化学式（１６）の構造が主であることがわかった。
【００７７】
【化１８】

【００７８】
得られたポリマー（４ｃ）１００重量部を１−メトキシ−２−プロパノール１０００重量部に溶解し、孔径０．２μmのフィルタで濾過した。それをシリコン基板上に回転塗布し、１００℃で２分間ベークして薄膜を得た。塗布膜（３００nm）をテトラメチルアンモニウムヒドロキシド水溶液（濃度０．３９７重量％）に浸したところ、干渉色が変化しながら、５秒間で溶け、残膜が０になった。上記溶液をフッ化リチウム基板上に塗布し、塗布膜の吸収スペクトルを真空紫外分光装置で測定したところ、１９３nmの吸光度が、膜厚１．０μmで０．２５であり、吸収が小さいことがわかった。
【００７９】
（合成例６）共重合体（５ｃ）の合成
合成例１で得たモノマー（１ａ）３．０ｇと、合成例４で得たモノマー（３ａ）３．１ｇをＴＨＦ５０ｍｌに溶解し、反応開始剤として２，２’−アゾビス（イソブチロニトリル）０．２９ｇを加え、７０℃で加熱還流して、６時間重合を行った。重合後、ｎ−ヘキサン５００ｍｌへ溶液を注ぎ、ポリマーを析出させ、これを乾燥して化学式（１７）で示す共重合体（５ａ）を得た。
【００８０】
【化１９】

【００８１】
ゲルパーミエーションクロマトグラフィーにより、テトラヒドロフラン中で、このポリマーのポリスチレン換算の分子量を調べたところ、重量平均分子量が４，９００、数平均分子量が３，８００であった。
【００８２】
上記のように合成したポリマー（５ａ）を、合成例２と同様に、過酢酸による酸化を行い、化学式（１８）で示すδ−ラクトン構造を有する重合体（５ｂ）を得た。
【００８３】
【化２０】

【００８４】
上記のように合成したポリマー（５ｂ）を、合成例２と同様に、水酸化ナトリウム水溶液により加水分解を行い、δ−ヒドロキシカルボン酸を有する重合体（５ｃ）を得た。得られたポリマーの構造は、種々の分析法から化学式（１９）の構造が主であることがわかった。
【００８５】
【化２１】

【００８６】
得られたポリマー（５ｃ）１００重量部を１−メトキシ−２−プロパノール１０００重量部に溶解し、孔径０．２μmのフィルタで濾過した。それをシリコン基板上に回転塗布し、１００℃で２分間ベークして薄膜を得た。塗布膜（３００nm）をテトラメチルアンモニウムヒドロキシド水溶液（濃度０．１１３重量％）に浸したところ、干渉色が変化しながら１５秒間で溶け、残膜が０になった。上記溶液をフッ化リチウム基板上に塗布した膜の吸収スペクトルを真空紫外分光装置で測定したところ、１９３nmの吸光度が膜厚１．０μmで０．２５であり、吸収が小さいことがわかった。
【００８７】
（合成例７）モノマー（６ａ）の合成
β−コレスタノール５．０ｇ、ピリジン１．２ｇをテトラヒドロフラン２００ｍｌに溶解し、これにアクリル酸クロリド１．３ｇをテトラヒドロフラン３０ｍｌに溶解した溶液を０℃で滴下した。滴下後、さらに室温で数時間攪拌し、沈殿したトリエチルアミンの塩酸塩を濾別した。この濾液に酢酸エチル１５０ｍｌを加え、水１００ｍｌで４回水洗し、有機層を無水硫酸ナトリウムで乾燥したのち、減圧下で溶媒を取り除くと、残分は結晶化した。これをエタノール／テトラヒドロフラン混合溶媒から再結晶を行い、化学式（２０）で示す白色の化合物（６ａ）を得た。
【００８８】
【化２２】

【００８９】
（合成例８）共重合体（７ｃ）の合成
合成例１で得たモノマー（１ａ）３．０ｇと、合成例７で得たモノマー（６ａ）１．７ｇをＴＨＦ５０ｍｌに溶解し、反応開始剤として２，２’−アゾビス（イソブチロニトリル）０．２ｇを加え、７０℃で加熱還流して、６時間重合を行った。重合後、ｎ−ヘキサン５００ｍｌへ溶液を注ぎ、ポリマーを析出させ乾燥して、化学式（２１）の共重合体（７ａ）を得た。
【００９０】
【化２３】

【００９１】
ゲルパーミエーションクロマトグラフィーにより、テトラヒドロフラン中で、このポリマーのポリスチレン換算の分子量を調べたところ、重量平均分子量が３，０００、数平均分子量２，５００であった。
【００９２】
上記のように合成したポリマー（７ａ）を、合成例２と同様に、過酢酸による酸化を行い、化学式（２２）で示すδ−ラクトン構造を有する重合体（７ｂ）を得た。
【００９３】
【化２４】

【００９４】
上記のように合成したポリマー（７ｂ）を、合成例２と同様に、水酸化ナトリウム水溶液により加水分解を行い、δ−ヒドロキシカルボン酸を有する重合体（７ｃ）を得た。得られたポリマーの構造は、種々の分析法から化学式（２３）で示す構造が主であることがわかった。
【００９５】
【化２５】

【００９６】
得られたポリマー（７ｃ）１００重量部を１−メトキシ−２−プロパノール１０００重量部に溶解し、孔径０．２μmのフィルタで濾過した。それをシリコン基板上に回転塗布し、１００℃で２分間ベークして薄膜を得た。塗布膜（３００nm）をテトラメチルアンモニウムヒドロキシド水溶液（濃度０．１１３重量％）に浸したところ、干渉色が変化しながら１５秒間で溶け、残膜が０になった。また、フッ化リチウム基板上に上記溶液を塗布した膜の吸収スペクトルは、真空紫外分光装置で測定した結果、波長１９３nmでの吸光度が膜厚１．０μmで０．２５であり、吸収が小さいことがわかった。
【００９７】
（合成例９）δ−ヒドロキシカルボン酸を有する低分子化合物（８ａ）の合成
アンドロステロン５．００ｇを酢酸１００ｍｌに溶解し、そこに過酸化水素水５０ｍｌを加え、５０℃で数時間攪拌した。反応後、溶媒を減圧留去して減らし、０．１Ｎ水酸化ナトリウム水溶液５０ｍｌとテトラヒドロフラン５ｍｌを加え、４時間加熱還流した。それに塩酸水溶液を徐々に加えて弱酸性にした。この溶液に酢酸エチル約１５０ｍｌを加えて抽出を２回行い、得られた有機層を１００ｍｌの水で２回洗浄した。洗浄後、有機層を無水硫酸ナトリウムで乾燥し、その後溶媒を減圧留去して白色の化合物（８ａ）を４ｇ得た。得られた化合物の構造は、種々の分析法から前記化学式（７）に示した構造であることがわかった。
【００９８】
次に、上記合成した化合物を用いた実施例を用いて、本発明をさらに詳しく述べる。
【００９９】
（実施例１）
合成例２で合成した重合体（２ｃ−１）１００重量部、酸発生剤トリフェニルスルホニウムトリフレート１重量部、２−ベンジルピリジン０．０１重量部を１−メトキシ−２−プロパノール１０００重量部に溶解し、孔径０．２μmのフッ素樹脂フィルタを用いて濾過した。
【０１００】
ヘキサメチルジシラザンで処理したシリコン基板上に、上記のレジスト溶液を回転塗布し、１００℃で２分間ベークして、膜厚０．３μmのレジスト膜を生成した。この膜の吸収スペクトルを、紫外可視分光光度計で測定したところ、波長１９３nmでの透過率は７０％であった。
【０１０１】
ＡｒＦエキシマレーザステッパーを用いて、レベンソン型の位相シフトマスクを介してこのレジスト膜の露光をおこない、１００℃で２分間の露光後ベークを行った。２３℃のテトラメチルアンモニウムヒドロキシド水溶液（０．１１３重量％）にレジスト膜を浸漬したところ、膜の未露光部は７秒で溶解した。そこで現像は、その２倍の時間の１４秒間行い、続いて、３０秒間純水でリンスした。
【０１０２】
その結果、１０ｍＪ／ｃｍ²で、ネガ型の０．１２μmラインアンドスペースパタンが得られた。この際、パタンの膨潤は見られなかった。なお、得られたパタンのついた基板を、テトラヒドロフランに浸漬したところ、パタンは瞬時に溶解し、架橋が起きていないことがわかった。
【０１０３】
また、加速電圧５０ｋＶの電子線描画装置を用いて、このレジストにラインアンドスペースパタンの露光を行った。露光後ベーク、現像はＡｒＦエキシマレーザ露光と同じ条件を用いたところ、露光量７μＣ／ｃｍ²で、ネガ型の０．１２μmラインアンドスペースパタンが得られた。この際、パタンの膨潤は見られなかった。
【０１０４】
また、このレジスト溶液は、室温（２３℃）で７日間保存しても感度、解像度に変化が無く、保存安定性がよいことがわかった。
【０１０５】
上記のレジスト膜について、ＣＨＦ₃ガスを用いて平行平板型の反応性イオンエッチング装置により、エッチングを行った。条件は、ＣＨＦ₃流量３５sccm、ガス圧１０ｍTorr、ＲＦバイアスパワー１５０Ｗを用いた。その結果、このレジストのエッチレートは、市販のノボラック樹脂を１．０とした場合に、１．２であり、ドライエッチング耐性が高いことがわかった。
【０１０６】
（実施例２）
実施例１で用いた重合体（２ｃ−１）の代わりに、合成例３で合成した重合体（２ｃ−２）を１００重量部、酸発生剤トリフェニルスルホニウムノナフレート１重量部、ヨウ化テトラメチルアンモニウム０．０１重量部をシクロヘキサノン１０００重量部に溶解し、孔径０．２μmのフッ素樹脂フィルタを用いて濾過した。
【０１０７】
実施例１と同様に、ヘキサメチルジシラザンで処理したシリコン基板上に、上記のレジスト溶液を回転塗布し、１００℃で２分間ベークして、膜厚０．３μmのレジスト膜を生成した。この膜の吸収スペクトルを、紫外可視分光光度計で測定したところ、１９３nmでの透過率は、７０％であった。
【０１０８】
実施例１と同様に位相シフトマスクを通じてＡｒＦエキシマレーザステッパーで露光し、その後１００℃で２分間露光後ベークを行った。２３℃のテトラメチルアンモニウムヒドロキシド水溶液（０．１１３重量％）にレジスト膜を浸漬したところ、膜の未露光部は１８秒で溶解した。そこで現像は、その２倍の時間の３６秒間行い、続いて、３０秒間純水でリンスした。その結果、５ｍＪ／ｃｍ²で、ネガ型の０．１２μmラインアンドスペースパタンが得られた。この際、パタンの膨潤は見られなかった。
【０１０９】
さらに上記のレジスト膜について、実施例１の条件でエッチングを行った。その結果、このレジストのエッチングレートは、市販のノボラック樹脂の塗膜のエッチングレートを１．０としたときに、１．２０であり、ドライエッチング耐性が高いことがわかった。
【０１１０】
（実施例３）
実施例１で用いた重合体（２ｃ−１）の代わりに、合成例５で合成した重合体（４ｃ）を１００重量部、酸発生剤Ｎ−トリフルオロメタンスルホニルオキシナフチルイミド１重量部、１，３，４，６−テトラキス（メトキシメチル）グルコルウリル１０重量部をジアセトンアルコール１０００重量部に溶解し、孔径０．２μmのフッ素樹脂フィルタを用いて濾過した。
【０１１１】
実施例１と同様に、ヘキサメチルジシラザンで処理したシリコン基板上に、上記のレジスト溶液を回転塗布し、１００℃で２分間ベークして、膜厚０．３μmのレジスト膜を生成した。この膜の吸収スペクトルを、紫外可視分光光度計で測定したところ、１９３nmの透過率は７４％であった。
【０１１２】
実施例１と同様に位相シフトマスクを通じてＡｒＦエキシマレーザステッパーで露光し、その後１００℃で２分間露光後ベークを行った。２３℃のテトラメチルアンモニウムヒドロキシド水溶液（０．３９７重量％）にレジスト膜を浸漬したところ、膜の未露光部は７秒で溶解した。そこで現像は、その２倍の時間の１４秒間行い、続いて、３０秒間純水でリンスした。その結果、１０ｍＪ／ｃｍ²で、ネガ型の０．１２μmラインアンドスペースパタンが得られた。この際、パタンの膨潤は見られなかった。
【０１１３】
（実施例４）
実施例１で用いた重合体（２ｃ−１）の代わりに、合成例６で合成した重合体（５ｃ）を１００重量部、酸発生剤ジメチルフェニルスルホニウムトリフレート３重量部、合成例９で合成した化合物（８ａ）１０重量部を１−メトキシ−２−プロパノール１０００重量部に溶解し、孔径０．２μmのフッ素樹脂フィルタを用いて濾過した。
【０１１４】
実施例１と同様に、ヘキサメチルジシラザンで処理したシリコン基板上に、上記のレジスト溶液を回転塗布し、１００℃で２分間ベークして、膜厚０．３μmのレジスト膜を生成した。この膜の吸収スペクトルを、紫外可視分光光度計で測定したところ、１９３nmの透過率は７３％であった。
【０１１５】
実施例１と同様に位相シフトマスクを通じてＡｒＦエキシマレーザステッパーで露光し、その後１００℃で２分間露光後ベークを行った。２３℃のテトラメチルアンモニウムヒドロキシド水溶液（０．１１３重量％）にレジスト膜を浸漬したところ、膜の未露光部は１８秒で溶解した。そこで現像は、その２倍の時間の３６秒間行い、続いて、３０秒間純水でリンスした。その結果１０ｍＪ／ｃｍ²でネガ型の０．１２μmラインアンドスペースパタンが得られた。この際、パタンの膨潤は見られなかった。
【０１１６】
（実施例５）
実施例１で用いた重合体（２ｃ−１）の代わりに、合成例８で合成した重合体（７ｃ）を１００重量部、酸発生剤トリフェニルスルホニウムトリフレート３重量部、２−ベンジルピリジン０．０１重量部を１−メトキシ−２−プロパノール１０００重量部に溶解し、孔径０．２μmのフッ素樹脂フィルタを用いて濾過した。
【０１１７】
実施例１と同様に、ヘキサメチルジシラザンで処理したシリコン基板上に、上記のレジスト溶液を回転塗布し、１００℃で２分間ベークして膜厚０．３μmのレジスト膜を生成した。この膜の吸収スペクトルを、紫外可視分光光度計で測定したところ、１９３nmの透過率は７０％であった。
【０１１８】
実施例１と同様に位相シフトマスクを通じてＡｒＦエキシマレーザステッパーで露光し、その後１００℃で２分間露光後ベークを行った。２３℃のテトラメチルアンモニウムヒドロキシド水溶液（０．１１３重量％）にレジスト膜を浸漬したところ、膜の未露光部は１７秒で溶解した。そこで現像は、その２倍の時間の３４秒間行い、続いて３０秒間純水でリンスした。その結果、５ｍＪ／ｃｍ²で、ネガ型の０．１２μmラインアンドスペースパタンが得られた。この際、パタンの膨潤は見られなかった。
【０１１９】
さらに上記のレジスト膜について、ＣＨＦ₃ガスを用いて平行平板型の反応性イオンエッチング装置により、エッチングを行った。条件は、ＣＨＦ₃流量３５sccm、ガス圧１０ｍTorr、ＲＦバイアスパワー１５０Ｗを用いた。その結果、このレジストのエッチレートは、市販のノボラック樹脂を１．０とした場合に、１．１５であり、ドライエッチング耐性が高いことがわかった。
【０１２０】
（実施例６）
図１に公知のＭＯＳ（金属−酸化物−半導体）型トランジスタの断面図を示す。図において１１は基板、１２はフィールド酸化膜、１３はソースコンタクト、１４はドレインコンタクト、１５は多結晶シリコン、１６はソース電極、１７はドレイン電極、１８はゲート電極、１９は保護膜である。同トランジスタは、ゲート電極１８に印加する電圧により、ソース電極１６およびドレイン電極１７間に流れるドレイン電流を制御する構造となっている。
【０１２１】
このような構造を作る工程は十数工程からなるが、それらを大きく分けると、フィールド酸化膜形成までの工程と、ゲート形成までの工程と、最終工程の３つにグループ分けすることができる。ここで、はじめのフィールド酸化膜形成までの工程（図２）には、窒化シリコン膜上でレジストパタンを形成する工程が含まれる。このフィールド酸化膜形成を以下の実施例の様にして行った。
【０１２２】
公知の方法により、図２（ａ）の様にｐ型シリコンウェハ２１上に５０nmの酸化膜２２を形成し、その上にプラズマＣＶＤにより２００nmの窒化シリコン膜２３を形成し、基板とする。
【０１２３】
この基板に実施例１に示した材料、方法により０．５０μmラインのレジストパタン２４の形成を行う（図２（ｂ））。このレジストパタン２４をマスクとして、公知の方法で窒化シリコン膜２３をエッチングした後（図２（ｃ））、このレジスト２４を再びマスクにして、チャンネルストッパのためのホウ素のイオン打ち込みを行う。レジスト２４を剥離後（図２（ｄ））、窒化シリコン膜２３をマスクとする選択酸化により、素子分離領域に１．２μmのフィールド酸化膜２５を形成する（図２（ｅ））。
【０１２４】
この後、公知の方法に従ってゲート形成工程と、最終工程を行った。窒化シリコン膜２３をエッチング後、ゲートを酸化し、多結晶シリコン２６の成長を行う（図２（ｆ））。この基板に、実施例１に示したパタン形成法方を用いて、０．１５μmラインのレジストパタン２７の形成を行う（図２（ｇ））。このレジストパタン２７をマスクとして、公知の方法で多結晶シリコン２６のエッチングを行い、ゲート２８を形成する（図２（ｈ））。
【０１２５】
以下の工程は図示を省略するが、ソース、ドレインの薄い酸化膜をエッチングし、ついで多結晶シリコンゲートとソース、ドレインにヒ素を拡散し、多結晶シリコンゲートとソース、ドレイン領域に酸化膜を形成する。ゲート、ソース、ドレインへのアルミニウム配線のためのコンタクトを開口し、アルミニウム蒸着とパタニングを行い、さらに保護膜を形成し、ボンディングのためのパッドを開口する。このようにして図１のようなＭＯＳ型トランジスタが形成される。
【０１２６】
ここではＭＯＳ型トランジスタについて、特にフィールド酸化膜の形成方法を記述したが、本発明はこれに限らないのは言うまでもなく、他の半導体素子の製造方法、工程に適用できる。
【０１２７】
〈実施例７〉
本発明の実施例１から５に示したパタン形成方法を使って半導体メモリ素子を作製した。図３は素子製造の主な工程を示す断面図である。図３（ａ）に示すように、Ｐ型のＳｉ半導体３１を基板に用い、その表面に公知の素子分離技術を用いて素子分離領域３２を形成する。次に、例えば厚さ１５０nmの多結晶Ｓｉと厚さ２００nmのＳｉＯ₂を積層した構造のワード線３３を形成し、さらに化学気相成長法を用いて例えば１５０nmのＳｉＯ₂を被着し、異方的に加工してワード線の側壁にＳｉＯ₂のサイドスペーサ３４を形成する。次に通常の方法でｎ拡散層３５を形成する。
【０１２８】
次に図３（ｂ）に示すように、通常の工程を経て多結晶Ｓｉまたは高融点金属金属シリサイドあるいはこれらの積層膜からなるデータ線３６を形成する。次に図３（ｃ）に示すように、通常の工程を経て多結晶Ｓｉからなる蓄積電極３８を形成する。その後、Ｔａ₂Ｏ₅、Ｓｉ₃Ｎ₄、ＳｉＯ₂、ＢＳＴ、ＰＺＴ、強誘電体、あるいはこれらの複合膜などを被着し、キャパシタ用絶縁膜３９を形成する。引き続き多結晶Ｓｉ、高融点金属、高融点金属シリサイド、あるいはＡｌ、Ｃｕ等の低抵抗な導体を被着しプレート電極４０を形成する。次に図３（ｄ）に示すように、通常の工程を経て配線４１を形成する。次に通常の配線形成工程やパッシベーション工程を経てメモリ素子を作製した。
【０１２９】
なお、ここでは、代表的な製造工程のみを説明したが、これ以外は通常の製造工程を用いた。また、各工程の順番が前後しても本発明は適用できる。上記素子製造工程におけるリソグラフィ工程ではほとんどの工程に本発明の実施例１から５に示したを適用したが、ネガ型レジストでパタン形成するのが不向きな工程やパタンの寸法が大きい工程には本発明は必ずしも適用する必要はない。例えばパッシベーション工程での導通孔形成工程や、イオン打ち込みマスク形成用工程のパタン形成には本発明は適用しなかった。
【０１３０】
次に、リソグラフィで形成したパタンについて説明する。図４は製造したメモリ素子のメモリ部の代表的なパタン配置を示す。４２がワード線、４３がデータ線、４４がアクティブ領域、４５が蓄積電極、４６が電極取り出し孔のパタンである。この例においても、ここに示した４６の電極取り出し孔形成以外のすべてに本発明の実施例１から３のパタン形成を用いた。ここに示したパタン形成以外でも最小設計ルールを用いている工程では本発明を用いた。
【０１３１】
本発明を用いて作製した素子は、従来法を用いて作製した素子と比較するとパタン間の寸法を小さくできた、そのため同じ構造の素子が小さくでき、半導体素子を製造する際に１枚のウェハから製造できる個数が増えて、歩留まりが向上した。
【０１３２】
【発明の効果】
本発明によれば、ＡｒＦエキシマレーザの波長１９３nmを含む遠紫外光領域で透明、かつドライエッチング耐性も高い化学構造を持ちながら、水性アルカリ現像液で微細パタンが膨潤することなく現像でき、解像性能の優れたネガ型の感放射線組成物、およびそれを用いたパタン形成方法、さらにはそれを用いた半導体装置の製造方法を提供できる。
【図面の簡単な説明】
【図１】ＭＯＳ（金属−酸化物−半導体）型トランジスタの断面図。
【図２】本発明のパタン形成方法を用いたフィールド酸化膜およびシリコンゲートの形成工程を示す断面図。
【図３】本発明のパタン形成方法を用いた半導体メモリ素子の製造工程を示す断面図。
【図４】メモリ素子を構成するメモリ部のパタン配置を示す平面図。
【符号の説明】
１１…基板、１２…フィールド酸化膜、１３…ソースコンタクト、１４…ドレインコンタクト、１５…多結晶シリコン、１６…ソース電極、１７…ドレイン電極、１８…ゲート電極、１９…保護膜、２２…酸化膜、２４…レジストパタン、２５…フィールド酸化膜、２６…多結晶シリコン膜、２７…レジストパタン、２８…多結晶シリコンゲート、３１…Ｐ型Ｓｉ半導体基板、３２…素子分離領域、３３…ワード線、３４…サイドスペーサ、３５…ｎ拡散層、３６…データ線、３８…蓄積電極、３９…キャパシタ用絶縁膜、４０…プレート電極、４１…配線、４２…ワード線、４３…データ線、４４…アクティブ領域、４６…電極取り出し孔。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photosensitive composition used in a fine processing technique in a manufacturing process of a semiconductor device or the like, a microlithography process using the same, and a method of manufacturing a semiconductor device or the like including the microlithography process. More specifically, a negative type suitable for an optical lithography process using far-ultraviolet light having a wavelength of 250 nm or less, such as ArF excimer laser light, which is a radiation source having a shorter wavelength than a high-pressure mercury lamp or KrF excimer laser, which is an existing ultraviolet light source. The present invention relates to a radiation-sensitive composition, a pattern forming method, and a semiconductor device manufacturing method.
[0002]
[Prior art]
Photolithography technology that creates micron or sub-micron fine patterns in electronic devices such as semiconductors has been at the heart of mass production micromachining technology. Recent demands for higher integration and higher density of semiconductor devices have led to many advances in microfabrication technology. In particular, as the minimum processing size approaches the exposure wavelength, photolithography technology using a high-pressure mercury lamp g-line (436 nm), i-line (365 nm) to KrF excimer laser (248 nm) and a light source with a shorter wavelength is developed. It has been. In response to these changes in exposure wavelength, materials corresponding to the respective wavelengths have been developed for photoresists.
[0003]
Conventionally, photoresists suitable for these wavelengths have different photosensitizers and photosensitivity mechanisms, but aqueous alkali development utilizing aqueous alkali solubility of resins or polymer materials having phenolic hydroxyl groups has been used industrially. I came. These resins or polymer materials inevitably contain a lot of aromatic rings, which are chemical structural elements that increase the etching resistance in the dry etching process after forming the resist pattern.
[0004]
In recent years, the expectation for photolithography using an ArF excimer laser (193 nm) as a light source is increasing for processing in a region where the minimum processing dimension is smaller than 0.25 microns. However, this wavelength is the absorption maximum due to the aromatic ring, and the range in which an exposure latent image can be formed is limited to the very surface of the photoresist film in a photoresist material mainly composed of an aromatic ring structure that has been used industrially. It was difficult to form a fine resist pattern by aqueous alkali development.
[0005]
PMMA (polymethyl methacrylate) or the like is known as a resist polymer material having a high transmittance at a wavelength of 193 nm of the ArF excimer laser, but this cannot apply industrially advantageous aqueous alkali development. Further, the dry etching resistance and sensitivity are far from practicality.
[0006]
On the other hand, various resist materials having high transmittance in this wavelength region and high dry etching resistance have been proposed. As a chemical structure that is transparent in the far ultraviolet region including the wavelength of 193 nm of an ArF excimer laser and that can impart dry etching resistance to a resist material, use of an adamantane skeleton instead of an aromatic ring is disclosed in Japanese Patent Laid-Open Nos. 4-39665 and 5- Similarly, the use of a norbornane skeleton is disclosed in JP-A-5-80515 and JP-A-5-257284.
[0007]
In addition to these structures, it is disclosed in JP-A-7-28237 and JP-A-8-259626 that alicyclic structures such as tricyclodecanyl groups are generally effective. JP-A-8-82925 describes that a compound having a terpenoid skeleton such as a menthyl group is transparent in the far ultraviolet region including a wavelength of 193 nm and can impart dry etching resistance to a resist material.
[0008]
For the same purpose, JP-A-8-15865 shows that dry etching resistance can be improved by mixing a substituted androstane compound with a composition using a polymer matrix that does not necessarily have high dry etching resistance. .
[0009]
Regarding resist materials that have a chemical structure that is transparent in the far-ultraviolet region including the wavelength of 193 nm of an ArF excimer laser and that enable aqueous alkali development, JP-A-4-39665, JP-A-4-184345, As disclosed in JP-A-4-226461, JP-A-5-80515, etc., attempts have been made to utilize a carboxylic acid structure of acrylic acid or methacrylic acid. In these, the aqueous alkali solubility of the portion dissolved in the developer by aqueous alkaline development is based on the carboxylic acid structure of acrylic acid or methacrylic acid.
[0010]
JP-A-8-259626 discloses a polymer compound in which a carboxylic acid group is added to an alicyclic structure introduced into a methacrylic acid ester side chain. These all enable aqueous alkali development by utilizing the carboxylic acid structure in the side chain portion of a vinyl polymerizable polymer such as acrylic acid or methacrylic acid ester.
[0011]
However, in the phenol structure conventionally used as an alkali-soluble group, pKa = 10.0 (phenol), whereas in these carboxylic acid structures, pKa = 4.8 (acetic acid) has a low value and is acidic. High degree. Therefore, when they are used as the alkali-soluble group of the base resin, generally, at the same molar fraction, the resin having a carboxylic acid structure has a higher dissolution rate in an aqueous alkali and the resin having a phenol structure is less soluble. Even in a concentrated alkaline developer, the resin having a carboxylic acid structure is dissolved.
[0012]
When a resin having a carboxylic acid as described above is used, if a cross-linking agent such as that disclosed in JP-A-62-164045 is used, a carboxylic acid having a high acidity remains in the cross-linked portion. There was a problem that the developing solution was infiltrated and swollen to deteriorate the resolution performance. In addition, as shown in JP-A-4-165359, when a compound having an inhibitory action on dissolution is formed by an acid generated by exposure, a resin having a carboxylic acid does not have a dissolution contrast, so that a negative resist is formed. There was a problem of not becoming.
[0013]
On the other hand, as a method for forming a non-swelled negative pattern using a resin having a carboxylic acid structure, a γ- or δ-hydroxycarboxylic acid structure found in JP-A-11-109627 is an acid-catalyzed reaction. Is known that utilizes a change to a γ-lactone or δ-lactone structure.
[0014]
[Problems to be solved by the invention]
invention Eyes In particular, it has a chemical structure that is transparent in the far ultraviolet region including the wavelength of 193 nm of an ArF excimer laser and has a high dry etching resistance, but has excellent resolution performance that enables development without swelling of fine patterns with an aqueous alkaline developer. Radiation sensitive composition For The present invention provides a negative pattern forming method. other An object is to provide a method of manufacturing a semiconductor device using such a pattern formation method.
[0015]
[Means for Solving the Problems]
Book invention Used for The radiation-sensitive composition contains at least a polymer having a repeating unit represented by the chemical formula (1) and an acid generator.
[0016]
[Chemical 3]

[0017]
Here, in the above chemical formula (1), R ¹ , R ² Is a hydrogen atom or a methyl group, x and y are any numbers satisfying x + y = 1, 0 <x ≦ 1, 0 ≦ y <1, respectively, and the weight average molecular weight of the polymer is 1,000 to 500, 000.
[0018]
The polymer having a repeating unit represented by the chemical formula (1) has an alicyclic structure, which is known to obtain high dry etching resistance, in the side chain, and is conjugated unsaturated with two or more. Since it has no bond, it is transparent in the far ultraviolet region including 193 nm. That is, the radiation-sensitive composition of the present invention has high dry etch resistance and transparency in the far ultraviolet region including 193 nm.
[0019]
In addition, the δ-hydroxycarboxylic acid structure of the polymer having the repeating unit represented by the chemical formula (1) has an alcohol that is a partner for esterification of the carboxylic acid at the δ position of the carboxylic acid in the molecule. In addition, esterification by an acid-catalyzed reaction is more likely to occur than usual. In addition, since the carboxylic acid and the hydroxyl group are contained in the same ring structure, they are close to each other sterically and are easily esterified. Therefore, the pattern can be formed with high sensitivity. Since this reaction is intramolecular esterification, cross-linking between molecules does not occur, and the amount of carboxylic acid simply changes between the exposed and unexposed areas. In addition, the produced ester is not hydrolyzed by a commonly used tetraalkylammonium hydroxide aqueous solution and is stable during development. For this reason, the dissolution rate is greatly changed, swelling is avoided, and a good fine pattern can be formed.
[0020]
The acid for causing the acid-catalyzed reaction is realized by using an acid generator that generates an acid upon irradiation with actinic radiation.
[0021]
In addition, the chemical formula (1) (R ¹ Is a hydrogen atom or a methyl group), a polymer having a repeating unit represented by the chemical formula (3) is subjected to hydrolysis reaction by partially or all of the δ-lactone ring structure of the polymer. -Obtained by having a hydroxycarboxylic acid structure.
[0022]
[Formula 4]

[0023]
By selecting the reaction conditions in this hydrolysis reaction, the ratio of the δ-hydroxycarboxylic acid structure and the δ-lactone structure in the polymer can be arbitrarily controlled. As a result, it is possible to control the dissolution rate in the developer and to increase the sensitivity of the resist. In addition, the ratio of the δ-hydroxycarboxylic acid structure in the polymer may be equal to or higher than the ratio that is soluble in the developer used by the film forming component.
[0024]
The polymer having the repeating unit represented by the chemical formula (3) is represented by the chemical formula (4) (R ¹ Can be easily derived by radical polymerization of an acrylic ester or methacrylic ester represented by a hydrogen atom or a methyl group, and further oxidizing the ketone structure to a δ-lactone structure with peracetic acid.
[0025]
[Chemical formula 5]

[0026]
At this time, a copolymer composed of the acrylic acid ester and the methacrylic acid ester may be used. By arbitrarily selecting the ratio of acrylic acid ester and methacrylic acid ester in the copolymer, the dissolution rate in the developer can be controlled. The acrylic acid ester or methacrylic acid ester can be easily obtained by esterifying acrylic acid or methacrylic acid with (epi) androsterone.
[0027]
In addition, the polymer may be a polymer in which a repeating unit represented by the chemical formula (1) is combined with an alicyclic group unit having no conjugated unsaturated bond in addition to the repeating unit represented by the chemical formula (1). The characteristic radiation-sensitive composition is also very effective in the present invention.
[0028]
[Chemical 6]

[0029]
Here, in the chemical formula (2), R ¹ , R ² , R ^Three Is a hydrogen atom or a methyl group, R ^Four Is an alicyclic structure having at least a conjugated unsaturated bond, and x, y, and z are arbitrary numbers satisfying x + y + z = 1, 0 <x ≦ 1, 0 ≦ y <1, 0 <z <1, respectively. The weight average molecular weight of the polymer is 1,000 to 500,000.
[0030]
In the above chemical formula (2), R ^Four Examples of the alicyclic group having no conjugated unsaturated bond represented by cyclohexyl group, tricyclo [5.2.1.0] decyl group, adamantyl group, norbornyl group, β-cholestanol group, cholesterol group, etc. However, it is not limited to these.
[0031]
The polymer having the repeating unit represented by the chemical formula (2) has both high dry etch resistance and transparency in the far ultraviolet region including 193 nm. Further, the δ-hydroxycarboxylic acid structure possessed by the polymer having the repeating unit represented by the chemical formula (2) is easily esterified and may have a pattern formation with high sensitivity. Further, since this reaction is intramolecular esterification, cross-linking between molecules does not occur, swelling is avoided, and a fine pattern can be formed. In addition, the produced ester is not hydrolyzed by a commonly used tetraalkylammonium hydroxide aqueous solution and is stable during development.
[0032]
This polymer can be obtained by converting a part or all of the δ-lactone ring structure of the polymer having a repeating unit represented by the chemical formula (5) into a δ-hydroxycarboxylic acid structure by hydrolysis reaction.
[0033]
[Chemical 7]

[0034]
Here, in the chemical formula (5), R ¹ , R ² Is a hydrogen atom or a methyl group, R ^Four Is an alicyclic structure having at least a conjugated unsaturated bond, and x and y are arbitrary numbers satisfying x + y = 1, 0 <x <1, 0 <y <1, respectively.
[0035]
The polymer having the repeating unit represented by the chemical formula (5) is a copolymer of the acrylic ester or methacrylic ester represented by the chemical formula (4) and the acrylic ester or methacrylic ester represented by the chemical formula (6). And further obtained by oxidation with peracetic acid.
[0036]
[Chemical 8]

[0037]
Here, in the above chemical formula (6), R ¹ Is a hydrogen atom or a methyl group, R ^Four Is an alicyclic structure having at least a conjugated unsaturated bond.
[0038]
The ratio of δ-lactone structure and alicyclic group structure in the polymer having the repeating unit represented by the chemical formula (5) can be easily selected by selecting the charging ratio of the monomer as the raw material of the copolymer and other polymerization conditions. Can be controlled arbitrarily. Furthermore, by selecting the reaction conditions in the hydrolysis reaction, the ratio of the δ-hydroxycarboxylic acid structure, δ-lactone structure and alicyclic group structure in the polymer having the repeating unit represented by the chemical formula (2) can be arbitrarily set. It is possible to control. As a result, it is possible to control the dissolution rate in the developer and increase the sensitivity of the resist, and at the same time, by introducing a bulky and hydrophobic alicyclic structure, it is possible to suppress swelling due to infiltration of the developer and to control acid diffusion. . In addition, the ratio of the δ-hydroxycarboxylic acid structure in the polymer may be equal to or higher than the ratio that is soluble in the developer used by the film forming component.
[0039]
In addition, the weight average molecular weight of the polymer in the radiation-sensitive composition of the present invention is preferably 1,000 to 500,000, more preferably 1,000 to 30,000. The acid generator is preferably used in an amount of 0.1 to 50 parts by weight, more preferably 0.5 to 20 parts by weight, based on the polymer.
[0040]
Examples of the acid generator include onium salts such as triphenylsulfonium triflate, triphenylsulfonium nonaflate, dimethylphenylsulfonium triflate, dimethyl-4-hydroxynaphthyl triflate, N-trifluoromethanesulfonyloxynaphthylimide, N-methane. Sulfonyloxyimide such as sulfonyloxynaphthylimide, N-trifluoromethanesulfonyloxy succinimide, N-perfluorooctanesulfonyloxy succinimide, and sulfonic acid ester, and the like. Actinic radiation such as ArF excimer laser However, the present invention is not limited to these as long as it generates an acid upon irradiation. Two or more of these acid generators may be used simultaneously.
[0041]
In addition, the radiation-sensitive composition of the present invention includes basic compounds such as 2-benzylpyridine, tripentylamine, triethanolamine, and iodide for improving resolution and improving process stability and storage stability. A salt such as tetramethylammonium chloride, tetrapentylammonium chloride, or tetraethylphosphonium iodide may be added. These basic compounds and salts are preferably added in an amount of 0.01 to 100 parts by weight with respect to 100 parts by weight of the acid generator used.
[0042]
In addition, the photosensitive composition of the present invention includes hexamethoxymethylmelamine, 1,3,4,6-tetrakis (methoxymethyl) glucoururil, 1,4-dioxane as a crosslinking agent in order to increase the heat resistance of the formed pattern. -2,3-diol etc. can be contained. These crosslinking agents are desirably used in an amount of 0.1 to 50 parts by weight with respect to 100 parts by weight of the film-forming component of the photosensitive composition.
[0043]
In addition, the photosensitive composition of the present invention is derived from cholic acid, abietic acid, and (epi) androsterone as a low-molecular compound having a carboxylic acid in order to control solubility in a developer and improve resolution. A compound represented by a possible chemical formula (7) or an oligomer in which a plurality of the above compounds are bonded can be contained. These low molecular weight compounds are desirably used in an amount of 1 to 50 parts by weight with respect to 100 parts by weight of the film-forming component of the photosensitive composition.
[0044]
[Chemical 9]

[0045]
In addition, the photosensitive composition of this invention is used by spin-coating to a board | substrate as a solution. As the solvent used in this case, any solvent may be used as long as the above-described constituent components are sufficiently dissolved and a uniform coating film can be formed by spin coating. Moreover, you may use individually or in mixture of 2 or more types.
[0046]
Book Invention pattern formation Method Are a step of forming a coating film made of any of the radiation-sensitive compositions described above on a predetermined substrate, a step of irradiating the coating film with an active actinic radiation of a predetermined pattern, and a substrate after irradiation with active radiation. And a step of exposing the coating film to an alkaline aqueous solution after the substrate is heated to remove unirradiated portions of active radiation.
[0047]
Examples of the active radiation used in the present invention include deep ultraviolet light of 250 nm or less and vacuum ultraviolet light such as ArF excimer laser light. An electron beam, EUV, X-ray, or the like can also be used. In the present invention, when actinic radiation having a predetermined pattern is irradiated, vacuum ultraviolet light such as ArF excimer laser light is usually formed into a predetermined pattern through a mask or a reticle. At this time, when a super-resolution technique represented by a modified illumination method or a phase shift mask is used, a higher resolution pattern can be obtained, which is desirable.
[0048]
The alkaline developer used in the present invention is preferably a tetraalkylammonium hydroxide aqueous solution having 1 to 5 carbon atoms.
[0049]
Book A method of manufacturing a semiconductor device according to the present invention includes a step of forming a resist pattern on a semiconductor substrate by any one of the above-described pattern forming methods and etching the substrate based on the resist pattern, or a step of implanting ions into the substrate Is included.
[0050]
Examples of the etching method used in the semiconductor manufacturing method of the present invention include dry etching methods such as plasma etching, reactive ion etching, and reactive ion beam etching, and wet etching methods.
[0051]
As a substrate to be processed in the method for manufacturing a semiconductor device of the present invention, a silicon dioxide film formed by a CVD method or a thermal oxidation method on a surface of single crystal silicon, an oxide film such as a coating glass film, or a silicon nitride film And the like. Moreover, various metal films, such as aluminum, its alloy, tungsten, a polycrystalline silicon, etc. are mentioned.
[0052]
An element, particularly a memory element, manufactured in the method for manufacturing a semiconductor device of the present invention can be finely patterned, so that the degree of integration can be increased. Therefore, since the elements can be made small, the number of elements that can be taken from one wafer is increased, and the yield is improved.
[0053]
DETAILED DESCRIPTION OF THE INVENTION
EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these. First, prior to examples, a synthesis example of materials used in the present invention will be shown.
[0054]
(Synthesis Example 1) Synthesis of monomer (1a)
Androsterone 5.0 g and pyridine 1.5 g were dissolved in tetrahydrofuran (THF) 200 ml, and a solution obtained by dissolving 1.6 g of acrylic acid chloride in 30 ml of tetrahydrofuran was added dropwise at 0 ° C. After dropping, the mixture was further stirred at room temperature for several hours, and the precipitated triethylamine hydrochloride was filtered off. After adding 150 ml of ethyl acetate to this filtrate and washing with water 4 times with 100 ml of water, the organic layer was dried over anhydrous sodium sulfate and the solvent was removed by placing it under reduced pressure, and the residue crystallized. This was recrystallized from a mixed solvent of ethanol / tetrahydrofuran to obtain a white compound monomer (1a) represented by the chemical formula (8).
[0055]
[Chemical Formula 10]

[0056]
(Synthesis Example 2) Synthesis of polymer (2c-1)
4.0 g of the monomer (1a) obtained in Synthesis Example 1 is dissolved in 40 ml of THF, 0.19 g of 2,2′-azobis (isobutyronitrile) is added as a reaction initiator, heated at 70 ° C. under reflux, 6 Time polymerization was performed. After the polymerization, the solution was poured into 500 ml of n-hexane to precipitate a polymer, which was dried to obtain a polymer (2a) represented by the chemical formula (9).
[0057]
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[0058]
When the molecular weight of this polymer in terms of polystyrene was examined in tetrahydrofuran by gel permeation chromatography (GPC), the weight average molecular weight was 2,800 and the number average molecular weight was 2,300.
[0059]
3.0 g of the polymer (2a) synthesized as described above was dissolved in 100 ml of tetrahydrofuran, 100 ml of acetic acid and 50 ml of hydrogen peroxide were added thereto, and the mixture was stirred at 50 ° C. for several hours. After the reaction, the solvent was distilled off under reduced pressure and poured into 500 ml of water. The precipitate was filtered off and dried to obtain a polymer (2b) having a δ-lactone structure given by chemical formula (10).
[0060]
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[0061]
2.5 g of the polymer (2b) synthesized as described above was dissolved in 100 ml of tetrahydrofuran, 150 ml of 0.5N aqueous sodium hydroxide solution was added, and the mixture was stirred for 2 hours. A hydrochloric acid aqueous solution was gradually added to make it weakly acidic. About 150 ml of ethyl acetate was added to this solution and extraction was performed twice. The obtained organic layer was washed twice with 100 ml of water, and the organic layer was dried over anhydrous sodium sulfate. Thereafter, the solvent was distilled off under reduced pressure and poured into 300 ml of n-hexane to precipitate a polymer, which was dried to obtain a white powdery polymer (2c-1). The structure of the obtained polymer was found to be mainly the structure of the chemical formula (11) by various analysis methods.
[0062]
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[0063]
100 parts by weight of the obtained polymer (2c-1) was dissolved in 1000 parts by weight of 1-methoxy-2-propanol and filtered through a filter having a pore size of 0.2 μm. It was spin-coated on a silicon substrate and baked at 100 ° C. for 2 minutes to obtain a thin film.
[0064]
When the coating film (300 nm) was immersed in an aqueous tetramethylammonium hydroxide solution (concentration: 0.113 wt%), it melted in 5 seconds while changing the interference color, and the remaining film became zero. Moreover, when the absorption spectrum of the film | membrane which apply | coated the said solution on the lithium fluoride board | substrate was measured with the vacuum ultraviolet spectrometer (made by ARC company), the light absorbency with respect to the far-ultraviolet light with a film thickness of 1.0 micrometer and wavelength 193nm is 0. It was found that the absorption was small.
[0065]
(Synthesis Example 3) Synthesis of polymer (2c-2)
2.5 g of the polymer (2b) having a δ-lactone structure synthesized in Synthesis Example 2 was dissolved in 100 ml of tetrahydrofuran, and the reaction conditions were milder than the hydrolysis reaction in Synthesis Example 2 (sodium hydroxide aqueous solution concentration was 0.2N). And the stirring time was 15 minutes). A hydrochloric acid aqueous solution was gradually added to make it weakly acidic. About 150 ml of ethyl acetate was added to this solution, extraction was performed twice, and the obtained organic layer was washed twice with 100 ml of water. After washing, the organic layer is dried over anhydrous sodium sulfate, and then the solvent is distilled off under reduced pressure and poured into 300 ml of n-hexane to precipitate a polymer, which is dried to give a white powdery polymer (2c-2) Got. According to various analytical methods, the obtained polymer was found to have a smaller proportion of the δ-hydroxycarboxylic acid structure in the polymer than the polymer (2c-1), and mainly the structure of the chemical formula (12).
[0066]
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[0067]
100 parts by weight of the obtained polymer (2c-2) was dissolved in 1000 parts by weight of 1-methoxy-2-propanol and filtered through a filter having a pore size of 0.2 μm. It was spin-coated on a silicon substrate and baked at 100 ° C. for 2 minutes to obtain a thin film.
[0068]
When the film (300 nm) applied on the silicon substrate was immersed in an aqueous tetramethylammonium hydroxide solution (concentration: 0.113 wt%), the interference color changed and dissolved in 15 seconds, and the remaining film became zero. Moreover, when the absorption spectrum of the film | membrane which apply | coated the said solution on the lithium fluoride board | substrate was measured with the vacuum ultraviolet spectrometer, the light absorbency with respect to far ultraviolet light with a film thickness of 1.0 micrometer and a wavelength of 193 nm is 0.25, It was found that the absorption was small.
[0069]
(Synthesis Example 4) Synthesis of monomer (3a)
5.0 g of androsterone and 1.5 g of pyridine were dissolved in 200 ml of tetrahydrofuran, and a solution of 1.7 g of methacrylic acid chloride dissolved in 30 ml of tetrahydrofuran was added dropwise at 0 ° C. After the dropwise addition, the mixture was further stirred at room temperature for several hours, and the precipitated triethylamine hydrochloride was filtered off. After adding 150 ml of ethyl acetate to the filtrate and washing with 100 ml of water four times, the organic layer was dried over anhydrous sodium sulfate and the solvent was removed by placing it under reduced pressure, and the residue crystallized. This was recrystallized from a mixed solvent of ethanol / tetrahydrofuran to obtain a white compound (3a) represented by the chemical formula (13).
[0070]
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[0071]
(Synthesis Example 5) Synthesis of polymer (4c)
4.0 g of the monomer (3a) obtained in Synthesis Example 4 was dissolved in 40 ml of THF, 0.18 g of 2,2′-azobis (isobutyronitrile) was added as a reaction initiator, and the mixture was heated to reflux at 70 ° C. Time polymerization was performed. After the polymerization, the solution was poured into 500 ml of n-hexane to precipitate a polymer, which was dried to obtain a polymer (4a) represented by the chemical formula (14).
[0072]
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[0073]
When the molecular weight of this polymer in terms of polystyrene was examined in tetrahydrofuran by gel permeation chromatography, the weight average molecular weight was 26,000 and the number average molecular weight was 20,000.
[0074]
The polymer (4a) synthesized as described above was oxidized with peracetic acid in the same manner as in Synthesis Example 2 to obtain a polymer (4b) having a δ-lactone structure represented by chemical formula (15).
[0075]
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[0076]
The polymer (4b) synthesized as described above was hydrolyzed with an aqueous sodium hydroxide solution in the same manner as in Synthesis Example 2 to obtain a polymer (4c) having a δ-hydroxycarboxylic acid. The structure of the obtained polymer was found to be mainly the structure of the chemical formula (16) from various analysis methods.
[0077]
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[0078]
100 parts by weight of the obtained polymer (4c) was dissolved in 1000 parts by weight of 1-methoxy-2-propanol and filtered through a filter having a pore size of 0.2 μm. It was spin-coated on a silicon substrate and baked at 100 ° C. for 2 minutes to obtain a thin film. When the coating film (300 nm) was immersed in an aqueous tetramethylammonium hydroxide solution (concentration: 0.397 wt%), the interference color changed and dissolved in 5 seconds, and the remaining film became zero. When the above solution was applied onto a lithium fluoride substrate and the absorption spectrum of the coating film was measured with a vacuum ultraviolet spectrometer, the absorbance at 193 nm was 0.25 at a film thickness of 1.0 μm, indicating that the absorption was small. It was.
[0079]
(Synthesis Example 6) Synthesis of copolymer (5c)
3.0 g of the monomer (1a) obtained in Synthesis Example 1 and 3.1 g of the monomer (3a) obtained in Synthesis Example 4 are dissolved in 50 ml of THF, and 2,2′-azobis (isobutyronitrile) is used as a reaction initiator. 0.29 g was added, and the mixture was heated to reflux at 70 ° C. for polymerization for 6 hours. After the polymerization, the solution was poured into 500 ml of n-hexane to precipitate a polymer, which was dried to obtain a copolymer (5a) represented by the chemical formula (17).
[0080]
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[0081]
When the molecular weight of this polymer in terms of polystyrene was examined in tetrahydrofuran by gel permeation chromatography, the weight average molecular weight was 4,900, and the number average molecular weight was 3,800.
[0082]
The polymer (5a) synthesized as described above was oxidized with peracetic acid in the same manner as in Synthesis Example 2 to obtain a polymer (5b) having a δ-lactone structure represented by the chemical formula (18).
[0083]
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[0084]
The polymer (5b) synthesized as described above was hydrolyzed with an aqueous sodium hydroxide solution in the same manner as in Synthesis Example 2 to obtain a polymer (5c) having a δ-hydroxycarboxylic acid. The structure of the obtained polymer was found to be mainly the structure of the chemical formula (19) from various analysis methods.
[0085]
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[0086]
100 parts by weight of the obtained polymer (5c) was dissolved in 1000 parts by weight of 1-methoxy-2-propanol and filtered through a filter having a pore size of 0.2 μm. It was spin-coated on a silicon substrate and baked at 100 ° C. for 2 minutes to obtain a thin film. When the coating film (300 nm) was immersed in an aqueous tetramethylammonium hydroxide solution (concentration: 0.113 wt%), it melted in 15 seconds while the interference color changed, and the remaining film became zero. When the absorption spectrum of the film | membrane which apply | coated the said solution on the lithium fluoride board | substrate was measured with the vacuum ultraviolet spectrometer, the light absorbency of 193 nm was 0.25 at the film thickness of 1.0 micrometer, and it turned out that absorption is small.
[0087]
Synthesis Example 7 Synthesis of monomer (6a)
β-cholestanol (5.0 g) and pyridine (1.2 g) were dissolved in tetrahydrofuran (200 ml), and a solution obtained by dissolving acrylic acid chloride (1.3 g) in tetrahydrofuran (30 ml) was added dropwise at 0 ° C. After the dropwise addition, the mixture was further stirred at room temperature for several hours, and the precipitated triethylamine hydrochloride was filtered off. To this filtrate was added 150 ml of ethyl acetate, washed with 100 ml of water four times, the organic layer was dried over anhydrous sodium sulfate, and then the solvent was removed under reduced pressure, and the residue crystallized. This was recrystallized from a mixed solvent of ethanol / tetrahydrofuran to obtain a white compound (6a) represented by the chemical formula (20).
[0088]
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[0089]
(Synthesis Example 8) Synthesis of copolymer (7c)
3.0 g of monomer (1a) obtained in Synthesis Example 1 and 1.7 g of monomer (6a) obtained in Synthesis Example 7 were dissolved in 50 ml of THF, and 2,2′-azobis (isobutyronitrile) was used as a reaction initiator. 0.2g was added, and it heated and refluxed at 70 degreeC, and superposed | polymerized for 6 hours. After the polymerization, the solution was poured into 500 ml of n-hexane, and the polymer was precipitated and dried to obtain a copolymer (7a) of the chemical formula (21).
[0090]
Embedded image

[0091]
When the molecular weight of this polymer in terms of polystyrene was examined in tetrahydrofuran by gel permeation chromatography, the weight average molecular weight was 3,000 and the number average molecular weight was 2,500.
[0092]
The polymer (7a) synthesized as described above was oxidized with peracetic acid in the same manner as in Synthesis Example 2 to obtain a polymer (7b) having a δ-lactone structure represented by the chemical formula (22).
[0093]
Embedded image

[0094]
The polymer (7b) synthesized as described above was hydrolyzed with an aqueous sodium hydroxide solution in the same manner as in Synthesis Example 2 to obtain a polymer (7c) having a δ-hydroxycarboxylic acid. The structure of the obtained polymer was found to be mainly the structure represented by the chemical formula (23) from various analytical methods.
[0095]
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[0096]
100 parts by weight of the obtained polymer (7c) was dissolved in 1000 parts by weight of 1-methoxy-2-propanol and filtered through a filter having a pore size of 0.2 μm. It was spin-coated on a silicon substrate and baked at 100 ° C. for 2 minutes to obtain a thin film. When the coating film (300 nm) was immersed in an aqueous tetramethylammonium hydroxide solution (concentration: 0.113 wt%), it melted in 15 seconds while the interference color changed, and the remaining film became zero. Further, the absorption spectrum of the film obtained by coating the above solution on a lithium fluoride substrate was measured with a vacuum ultraviolet spectroscope, and as a result, the absorbance at a wavelength of 193 nm was 0.25 at a film thickness of 1.0 μm, and the absorption was small. I understood.
[0097]
Synthesis Example 9 Synthesis of low molecular compound (8a) having δ-hydroxycarboxylic acid
Androsterone (5.00 g) was dissolved in acetic acid (100 ml), hydrogen peroxide solution (50 ml) was added thereto, and the mixture was stirred at 50 ° C. for several hours. After the reaction, the solvent was distilled off under reduced pressure, 50 ml of 0.1N aqueous sodium hydroxide solution and 5 ml of tetrahydrofuran were added, and the mixture was heated to reflux for 4 hours. A hydrochloric acid aqueous solution was gradually added to make it weakly acidic. About 150 ml of ethyl acetate was added to this solution, extraction was performed twice, and the obtained organic layer was washed twice with 100 ml of water. After washing, the organic layer was dried over anhydrous sodium sulfate, and then the solvent was distilled off under reduced pressure to obtain 4 g of a white compound (8a). The structure of the obtained compound was found to be the structure represented by the chemical formula (7) from various analytical methods.
[0098]
Next, the present invention will be described in more detail using examples using the synthesized compounds.
[0099]
Example 1
100 parts by weight of the polymer (2c-1) synthesized in Synthesis Example 2, 1 part by weight of the acid generator triphenylsulfonium triflate, and 0.01 parts by weight of 2-benzylpyridine are added to 1000 parts by weight of 1-methoxy-2-propanol. It melt | dissolved and filtered using the fluororesin filter with the hole diameter of 0.2 micrometer.
[0100]
The above resist solution was spin-coated on a silicon substrate treated with hexamethyldisilazane and baked at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.3 μm. When the absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer, the transmittance at a wavelength of 193 nm was 70%.
[0101]
This resist film was exposed through a Levenson-type phase shift mask using an ArF excimer laser stepper, and post-exposure baking was performed at 100 ° C. for 2 minutes. When the resist film was immersed in an aqueous solution of tetramethylammonium hydroxide (0.113 wt%) at 23 ° C., the unexposed part of the film was dissolved in 7 seconds. Therefore, development was carried out for 14 seconds, which is twice as long, and then rinsed with pure water for 30 seconds.
[0102]
As a result, 10 mJ / cm ² Thus, a negative type 0.12 μm line and space pattern was obtained. At this time, no pattern swelling was observed. When the obtained substrate with the pattern was immersed in tetrahydrofuran, it was found that the pattern dissolved instantaneously and no cross-linking occurred.
[0103]
The resist was exposed to a line and space pattern using an electron beam drawing apparatus with an acceleration voltage of 50 kV. Post exposure bake and development were performed under the same conditions as ArF excimer laser exposure. ² Thus, a negative type 0.12 μm line and space pattern was obtained. At this time, no pattern swelling was observed.
[0104]
The resist solution was found to have good storage stability with no change in sensitivity and resolution even when stored at room temperature (23 ° C.) for 7 days.
[0105]
For the above resist film, CHF _Three Etching was performed by a parallel plate type reactive ion etching apparatus using gas. Conditions are CHF _Three A flow rate of 35 sccm, a gas pressure of 10 mTorr, and an RF bias power of 150 W were used. As a result, the etch rate of this resist was 1.2 when the commercially available novolak resin was 1.0, indicating that the dry etching resistance was high.
[0106]
(Example 2)
Instead of the polymer (2c-1) used in Example 1, 100 parts by weight of the polymer (2c-2) synthesized in Synthesis Example 3, 1 part by weight of acid generator triphenylsulfonium nonaflate, tetraiodide 0.01 parts by weight of methylammonium was dissolved in 1000 parts by weight of cyclohexanone and filtered using a fluororesin filter having a pore size of 0.2 μm.
[0107]
In the same manner as in Example 1, the above resist solution was spin-coated on a silicon substrate treated with hexamethyldisilazane and baked at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.3 μm. When the absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer, the transmittance at 193 nm was 70%.
[0108]
In the same manner as in Example 1, exposure was performed with an ArF excimer laser stepper through a phase shift mask, and then post-exposure baking was performed at 100 ° C. for 2 minutes. When the resist film was immersed in an aqueous solution of tetramethylammonium hydroxide (0.113% by weight) at 23 ° C., the unexposed part of the film was dissolved in 18 seconds. Therefore, development was performed for 36 seconds, which is twice as long, and then rinsed with pure water for 30 seconds. As a result, 5mJ / cm ² Thus, a negative type 0.12 μm line and space pattern was obtained. At this time, no pattern swelling was observed.
[0109]
Further, the resist film was etched under the conditions of Example 1. As a result, the etching rate of this resist was 1.20 when the etching rate of a commercially available novolak resin coating film was 1.0, indicating that the dry etching resistance was high.
[0110]
Example 3
Instead of the polymer (2c-1) used in Example 1, 100 parts by weight of the polymer (4c) synthesized in Synthesis Example 5 and 1 part by weight of an acid generator N-trifluoromethanesulfonyloxynaphthylimide, 10 parts by weight of 3,4,6-tetrakis (methoxymethyl) glucoururil was dissolved in 1000 parts by weight of diacetone alcohol and filtered using a fluororesin filter having a pore size of 0.2 μm.
[0111]
In the same manner as in Example 1, the above resist solution was spin-coated on a silicon substrate treated with hexamethyldisilazane and baked at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.3 μm. When the absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer, the transmittance at 193 nm was 74%.
[0112]
In the same manner as in Example 1, exposure was performed with an ArF excimer laser stepper through a phase shift mask, and then post-exposure baking was performed at 100 ° C. for 2 minutes. When the resist film was immersed in an aqueous solution of tetramethylammonium hydroxide (0.397% by weight) at 23 ° C., the unexposed part of the film was dissolved in 7 seconds. Therefore, development was carried out for 14 seconds, which is twice as long, and then rinsed with pure water for 30 seconds. As a result, 10 mJ / cm ² Thus, a negative type 0.12 μm line and space pattern was obtained. At this time, no pattern swelling was observed.
[0113]
(Example 4)
Instead of the polymer (2c-1) used in Example 1, 100 parts by weight of the polymer (5c) synthesized in Synthesis Example 6 and 3 parts by weight of the acid generator dimethylphenylsulfonium triflate were synthesized in Synthesis Example 9. 10 parts by weight of the compound (8a) was dissolved in 1000 parts by weight of 1-methoxy-2-propanol and filtered using a fluororesin filter having a pore size of 0.2 μm.
[0114]
In the same manner as in Example 1, the above resist solution was spin-coated on a silicon substrate treated with hexamethyldisilazane and baked at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.3 μm. When the absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer, the transmittance at 193 nm was 73%.
[0115]
In the same manner as in Example 1, exposure was performed with an ArF excimer laser stepper through a phase shift mask, and then post-exposure baking was performed at 100 ° C. for 2 minutes. When the resist film was immersed in an aqueous solution of tetramethylammonium hydroxide (0.113% by weight) at 23 ° C., the unexposed part of the film was dissolved in 18 seconds. Therefore, development was performed for 36 seconds, which is twice as long, and then rinsed with pure water for 30 seconds. As a result, 10mJ / cm ² Thus, a negative 0.12 μm line and space pattern was obtained. At this time, no pattern swelling was observed.
[0116]
(Example 5)
Instead of the polymer (2c-1) used in Example 1, 100 parts by weight of the polymer (7c) synthesized in Synthesis Example 8, 3 parts by weight of acid generator triphenylsulfonium triflate, 2-benzylpyridine 0 .01 part by weight was dissolved in 1000 parts by weight of 1-methoxy-2-propanol and filtered using a fluororesin filter having a pore size of 0.2 μm.
[0117]
As in Example 1, the above resist solution was spin-coated on a silicon substrate treated with hexamethyldisilazane and baked at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.3 μm. When the absorption spectrum of this film was measured with an ultraviolet-visible spectrophotometer, the transmittance at 193 nm was 70%.
[0118]
In the same manner as in Example 1, exposure was performed with an ArF excimer laser stepper through a phase shift mask, and then post-exposure baking was performed at 100 ° C. for 2 minutes. When the resist film was immersed in an aqueous solution of tetramethylammonium hydroxide (0.113% by weight) at 23 ° C., the unexposed part of the film was dissolved in 17 seconds. Therefore, development was performed for 34 seconds, which is twice as long, and then rinsed with pure water for 30 seconds. As a result, 5mJ / cm ² Thus, a negative type 0.12 μm line and space pattern was obtained. At this time, no pattern swelling was observed.
[0119]
Furthermore, about said resist film, it is CHF. _Three Etching was performed by a parallel plate type reactive ion etching apparatus using gas. Conditions are CHF _Three A flow rate of 35 sccm, a gas pressure of 10 mTorr, and an RF bias power of 150 W were used. As a result, the etch rate of this resist was 1.15 when the commercially available novolak resin was 1.0, indicating that the dry etching resistance was high.
[0120]
(Example 6)
FIG. 1 shows a cross-sectional view of a known MOS (metal-oxide-semiconductor) type transistor. In the figure, 11 is a substrate, 12 is a field oxide film, 13 is a source contact, 14 is a drain contact, 15 is polycrystalline silicon, 16 is a source electrode, 17 is a drain electrode, 18 is a gate electrode, and 19 is a protective film. The transistor has a structure in which a drain current flowing between the source electrode 16 and the drain electrode 17 is controlled by a voltage applied to the gate electrode 18.
[0121]
The process for forming such a structure is composed of more than a dozen processes. If these are roughly divided, they can be grouped into three processes: a process up to forming a field oxide film, a process up to gate formation, and a final process. Here, the process up to the first field oxide film formation (FIG. 2) includes a process of forming a resist pattern on the silicon nitride film. The field oxide film was formed as in the following examples.
[0122]
As shown in FIG. 2A, a 50 nm oxide film 22 is formed on a p-type silicon wafer 21 by a known method, and a 200 nm silicon nitride film 23 is formed thereon by plasma CVD to form a substrate.
[0123]
A 0.50 μm line resist pattern 24 is formed on the substrate by the material and method shown in Example 1 (FIG. 2B). After etching the silicon nitride film 23 by a known method using the resist pattern 24 as a mask (FIG. 2C), boron ion implantation for a channel stopper is performed using the resist 24 again as a mask. After removing the resist 24 (FIG. 2D), a field oxide film 25 of 1.2 μm is formed in the element isolation region by selective oxidation using the silicon nitride film 23 as a mask (FIG. 2E).
[0124]
Thereafter, a gate forming step and a final step were performed according to a known method. After etching the silicon nitride film 23, the gate is oxidized to grow a polycrystalline silicon 26 (FIG. 2F). A resist pattern 27 of 0.15 μm line is formed on this substrate using the pattern forming method shown in Example 1 (FIG. 2G). Using this resist pattern 27 as a mask, the polycrystalline silicon 26 is etched by a known method to form a gate 28 (FIG. 2H).
[0125]
Although the following steps are not shown, the thin oxide films of the source and drain are etched, and then arsenic is diffused into the polycrystalline silicon gate, the source, and the drain, and an oxide film is formed in the polycrystalline silicon gate, the source, and the drain region. To do. Contacts for aluminum wiring to the gate, source and drain are opened, aluminum deposition and patterning are performed, a protective film is further formed, and pads for bonding are opened. In this way, a MOS transistor as shown in FIG. 1 is formed.
[0126]
Although a method for forming a field oxide film has been particularly described here for a MOS transistor, the present invention is not limited to this and can be applied to other methods and processes for manufacturing semiconductor devices.
[0127]
<Example 7>
A semiconductor memory device was fabricated using the pattern forming method shown in Examples 1 to 5 of the present invention. FIG. 3 is a cross-sectional view showing the main steps of device manufacture. As shown in FIG. 3A, a P-type Si semiconductor 31 is used as a substrate, and an element isolation region 32 is formed on the surface thereof using a known element isolation technique. Next, for example, polycrystalline Si having a thickness of 150 nm and SiO having a thickness of 200 nm. ₂ A word line 33 having a laminated structure is formed, and further, for example, 150 nm of SiO 2 is formed by chemical vapor deposition. ₂ And anisotropically processed to form SiO on the side wall of the word line ₂ Side spacers 34 are formed. Next, the n diffusion layer 35 is formed by a normal method.
[0128]
Next, as shown in FIG. 3B, a data line 36 made of polycrystalline Si, refractory metal metal silicide, or a laminated film thereof is formed through a normal process. Next, as shown in FIG. 3C, a storage electrode 38 made of polycrystalline Si is formed through a normal process. Then Ta ₂ O _Five , Si _Three N _Four , SiO ₂ , BST, PZT, ferroelectric, or a composite film thereof is deposited to form a capacitor insulating film 39. Subsequently, a polycrystalline silicon, a high melting point metal, a high melting point metal silicide, or a low resistance conductor such as Al or Cu is deposited to form the plate electrode 40. Next, as shown in FIG. 3D, a wiring 41 is formed through a normal process. Next, a memory element was manufactured through a normal wiring formation process and a passivation process.
[0129]
In addition, although only the typical manufacturing process was demonstrated here, the normal manufacturing process was used except this. Further, the present invention can be applied even if the order of each step is changed. In most of the lithography processes in the above-described element manufacturing process, the processes shown in the first to fifth embodiments of the present invention are applied. The invention does not necessarily have to be applied. For example, the present invention is not applied to a conductive hole forming step in the passivation step and a pattern formation in the ion implantation mask forming step.
[0130]
Next, a pattern formed by lithography will be described. FIG. 4 shows a typical pattern arrangement of the memory portion of the manufactured memory element. 42 is a word line, 43 is a data line, 44 is an active region, 45 is a storage electrode, and 46 is an electrode extraction hole pattern. Also in this example, the pattern formation of Examples 1 to 3 of the present invention was used for all except 46 electrode extraction hole formation shown here. The present invention is used in a process using the minimum design rule other than the pattern formation shown here.
[0131]
The device manufactured using the present invention can reduce the size between the patterns compared to the device manufactured using the conventional method. Therefore, the device having the same structure can be made small, and one wafer can be manufactured when manufacturing a semiconductor device. The number of products that can be manufactured from has increased, and the yield has improved.
[0132]
【The invention's effect】
According to the present invention, it is possible to develop without swelling a fine pattern with an aqueous alkaline developer while having a chemical structure that is transparent in the far ultraviolet region including the wavelength of 193 nm of an ArF excimer laser and has a high dry etching resistance. It is possible to provide a negative radiation sensitive composition having excellent performance, a pattern forming method using the same, and a method for manufacturing a semiconductor device using the same.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a MOS (metal-oxide-semiconductor) transistor.
FIG. 2 is a cross-sectional view showing a step of forming a field oxide film and a silicon gate using the pattern forming method of the present invention.
FIG. 3 is a cross-sectional view showing a manufacturing process of a semiconductor memory device using the pattern forming method of the present invention.
FIG. 4 is a plan view showing a pattern arrangement of a memory portion constituting a memory element.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Substrate, 12 ... Field oxide film, 13 ... Source contact, 14 ... Drain contact, 15 ... Polycrystalline silicon, 16 ... Source electrode, 17 ... Drain electrode, 18 ... Gate electrode, 19 ... Protective film, 22 ... Oxide film 24 ... resist pattern, 25 ... field oxide film, 26 ... polycrystalline silicon film, 27 ... resist pattern, 28 ... polycrystalline silicon gate, 31 ... P-type Si semiconductor substrate, 32 ... element isolation region, 33 ... word line, 34 ... side spacer, 35 ... n diffusion layer, 36 ... data line, 38 ... storage electrode, 39 ... capacitor insulating film, 40 ... plate electrode, 41 ... wiring, 42 ... word line, 43 ... data line, 44 ... active Region 46: Electrode extraction hole.

Claims (10)

A step of forming a coating film of a radiation-sensitive composition containing a polymer having a repeating unit represented by the chemical formula (1) and an acid generator on a predetermined substrate, and a step of irradiating the coating film with actinic radiation And a step of developing the coating film with a developer comprising an alkaline aqueous solution .

In the above chemical formula (1), R ¹ and R ² are hydrogen atoms or methyl groups, and x and y are arbitrary numbers satisfying x + y = 1, 0 <x ≦ 1, 0 ≦ y <1, respectively. The weight average molecular weight of the polymer is 1,000 to 500,000. A step of forming a coating film of a radiation-sensitive composition containing a polymer having a repeating unit represented by the chemical formula (2) and an acid generator on a predetermined substrate, and a step of irradiating the coating film with actinic radiation And a step of developing the coating film with a developer comprising an alkaline aqueous solution .

However, in the above chemical formula (2), R ¹ , R ² and R ³ are hydrogen atoms or methyl groups, R ⁴ is an alicyclic structure having at least a conjugated unsaturated bond, and x, y and z are respectively x + y + z = 1, 0 <x ≦ 1, 0 ≦ y <1,0 <z <1, and the polymer has a weight average molecular weight of 1,000 to 500,000. A step of forming a coating film of a radiation-sensitive composition containing a polymer having a repeating unit represented by the chemical formula (1) and an acid generator on a semiconductor substrate; and a step of irradiating the coating film with actinic radiation. And a step of developing the coating film with a developer comprising an alkaline aqueous solution .

In the above chemical formula (1), R ¹ and R ² are hydrogen atoms or methyl groups, and x and y are arbitrary numbers satisfying x + y = 1, 0 <x ≦ 1, 0 ≦ y <1, respectively. The weight average molecular weight of the polymer is 1,000 to 500,000. A step of forming a coating film of a radiation-sensitive composition containing a polymer having a repeating unit represented by the chemical formula (2) and an acid generator on a semiconductor substrate; and a step of irradiating the coating film with actinic radiation. And a step of developing the coating film with a developer comprising an alkaline aqueous solution .

However, in the above chemical formula (2), R ¹ , R ² and R ³ are hydrogen atoms or methyl groups, R ⁴ is an alicyclic structure having at least a conjugated unsaturated bond, and x, y and z are respectively x + y + z = 1, 0 <x ≦ 1, 0 ≦ y <1,0 <z <1, and the polymer has a weight average molecular weight of 1,000 to 500,000. 5. The method of manufacturing a semiconductor device according to claim 3, wherein the actinic radiation has a wavelength of 250. nm A method for manufacturing a semiconductor device, characterized by using the following far ultraviolet light. 6. The method of manufacturing a semiconductor device according to claim 5, wherein the actinic radiation is ArF excimer laser light. 5. The method of manufacturing a semiconductor device according to claim 3, wherein the developer is an aqueous solution containing tetramethylammonium hydroxide. Forming a coating film of a radiation-sensitive composition containing a polymer having a repeating unit represented by the chemical formula (1) on a semiconductor substrate; irradiating the coating film with active radiation; and A method for manufacturing a semiconductor device, comprising: a step of forming a line pattern by developing with a developer comprising an aqueous solution; and a step of dry etching the semiconductor substrate having the coating film.

However, in the above chemical formula (1), R ¹ , R ² Is a hydrogen atom or a methyl group, x and y are any numbers satisfying x + y = 1, 0 <x ≦ 1, 0 ≦ y <1, respectively, and the weight average molecular weight of the polymer is 1,000 to 500, 000. Forming a coating film of a radiation-sensitive composition containing a polymer having a repeating unit represented by the chemical formula (1) on a semiconductor substrate; irradiating the coating film with active radiation; and A method for manufacturing a semiconductor device, comprising: a step of forming a line pattern by developing with a developer comprising an aqueous solution; and a step of dry etching the semiconductor substrate having the coating film.

However, in the above chemical formula (2), R ¹ , R ² , R ^Three Is a hydrogen atom or a methyl group, R ^Four Is an alicyclic structure having at least a conjugated unsaturated bond, and x, y, and z are arbitrary numbers satisfying x + y + z = 1, 0 <x ≦ 1, 0 ≦ y <1, 0 <z <1, respectively. The weight average molecular weight of the polymer is 1,000 to 500,000. A step of forming a coating film of a radiation-sensitive composition containing a polymer having a repeating unit represented by the chemical formula (5) and an acid generator on a semiconductor substrate; and a step of irradiating the coating film with actinic radiation. And a step of developing the coating film with a developer composed of an alkaline aqueous solution to form a line pattern .

Here, in the chemical formula (5), R ¹ and R ² are hydrogen atoms or methyl groups, R ⁴ is an alicyclic structure having at least a conjugated unsaturated bond, and x and y are x + y = 1, 0, respectively. <X <1, 0 <y <1 is an arbitrary number.

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