JP2004177666A - Material for forming base layer film for lithography and method for forming wiring by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base layer film material having high absorptivity of exposure light and excellent durability against a photoresist developer solution, being removable by using a photoresist stripping liquid after used and making rework of the substrate easy, and to provide a method for forming wiring by using the base layer film material. <P>SOLUTION: The base layer film material is prepared by incorporating as a resin component a resin having at least a substituent which leaves the end group to produce a sulfonic acid residue when specified energy is applied. As for the resin component, a compound having at least a repeating unit expressed by formula (1) is preferable. In formula (1), n represents an integer of ≥1, X represents a 1-10C straight-chain or branched alkyl chain, an aromatic or alicyclic cyclic alkyl chain, or an alkyl ester chain, Y represents a substituent which produces a sulfonic acid residue when specified energy is applied. <P>COPYRIGHT: (C)2004,JPO

Description

（式中、ｎは１以上の整数を表し、Ｘは炭素原子数１〜１０の直鎖もしくは分岐状のアルキル鎖、芳香性もしくは脂環性の環状アルキル鎖、アルキルエステル鎖であり、Ｙは所定のエネルギーの印加を受けてスルホン酸残基を生じる置換基である。）
で表される繰り返し単位を有することを特徴とする。
【００２４】
前記スルホン酸残基を生じさせるために印加される所定のエネルギーとしては、例えば、８０℃以上の加熱処理等でスルホン酸残基を生じさせることができる。このような所定のエネルギーの印加は剥離処理における加熱とアルカリの協奏作用によりさらに促進される。
【００２５】
前記一般式（１）の置換基Ｙとしては、−ＳＯ_３Ｒ_１もしくは−ＳＯ_３ ⁻Ｒ_２ ^＋（式中、Ｒ_１およびＲ_２は１価の有機基）が好ましい。
【００２６】
前記有機基Ｒ_１としては、炭素原子数１〜１０のアルキル基、あるいはヒドロキシアルキル基のなかから選ばれる１種が好ましい。
【００２７】
また、前記有機基Ｒ_２としては、アルカノールアミン、およびアルキルアミンの中から選ばれる少なくとも１種が好ましい。
【００２８】
さらに、前記所定のエネルギーが印加されることにより末端基が脱離してスルホン酸残基を生じる置換基を少なくとも有する樹脂成分として、前述のいずれかの樹脂成分と、アクリル酸またはメタアクリル酸あるいはそれらの誘導体との共重合体あるいは混合樹脂を用いてもよい。
【００２９】
樹脂成分として、前記共重合体あるいは混合樹脂を用いる場合、その重合比あるいは混合比は、２．３８ｗｔ％ＴＭＡＨ現像液に対する耐性があり、レジスト剥離液にて除去できるという効果を維持できる範囲にあれば、特に限定されない。
【００３０】
さらにまた、前記所定のエネルギーが印加されることにより末端基が脱離してスルホン酸残基を生じる置換基を少なくとも有する樹脂成分として、
前述のいずれかの樹脂成分とアクリル酸またはメタアクリル酸あるいはそれらの誘導体との共重合体あるいは混合樹脂に対して、下記一般式（２）
【化４】

（式中、ｎは１以上の整数を表し、Ｒ_３は水素原子、フッ素原子、水酸基、カルボキシル基、炭素原子数１〜５のヒドロキシアルキル基、炭素原子数１〜５のアルコキシアルキル基の中から選ばれる少なくとも１種であり、Ｚは炭素原子数１〜１０の直鎖もしくは分岐状のアルキル鎖、芳香性もしくは脂環性の環状アルキル鎖、アルキルエステル鎖である。）
で表される繰り返し単位を共重合させた共重合体もしくは前記一般式（２）で表される繰り返し単位を有する樹脂化合物を混合させた混合樹脂からなる樹脂成分を用いてもよい。
【００３１】
前記一般式（２）の誘導体を用いて共重合体を調製し、その共重合体を樹脂成分として下層膜材料を構成すれば、樹脂成分のユニットにアントラセンが含まれることになり、このアントラセンは、特にＫｒＦエキシマレーザを用いたリソグラフィーにおいて吸収特性が高く、好ましい。
【００３２】
本発明の下層膜形成材料に用いる溶媒としては、従来の下層膜形成材料に用いられるものであれば、特に制限することなく用いることができる。
【００３３】
具体的には、例えば、アセトン、メチルエチルケトン、シクロペンタノン、シクロヘキサノン、メチルイソアミルケトン、２−ヘプタノン、１，１，１−トリメチルアセトン等のケトン類；エチレングリコール、エチレングリコールモノメチルエーテル、エチレングリコールモノエチルエーテル、エチレングリコールモノブチルエーテル、エチレングリコールモノアセテート、エチレングリコールモノメチルエーテルアセテート、エチレングリコールモノエチルエーテルアセテート、ジエチレングリコール、ジエチレングリコールモノアセテート、ジエチレングリコールモノメチルエーテル、ジエチレングリコールモノエチルエーテル、ジエチ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、プロピレングリコールモノメチルエーテル、ジプロピレングリコールモノメチルエーテル、グリセリン、１，２−ブチレングリコール、１，３−ブチレングリコール、２，３−ブチレングリコール等の多価アルコール類およびその誘導体；ジオキサンのような環状エーテル類；乳酸エチル、酢酸メチル、酢酸エチル、酢酸ブチル、ピルビン酸メチル、ピルビン酸エチル、３−メトキシプロピオン酸メチル、３−エトキシプロピオン酸エチル等のエステル類；ジメチルスルホキシド等のスルホキシド類；ジメチルスルホン、ジエチルスルホン、ビス（２−ヒドロキシエチル）スルホン、テトラメチレンスルホン等のスルホン類；Ｎ，Ｎ−ジメチルホルムアミド、Ｎ−メチルホルムアミド、Ｎ，Ｎ−ジメチルアセトアミド、Ｎ−メチルアセトアミド、Ｎ，Ｎ−ジエチルアセトアミド等のアミド類；Ｎ−メチル−２−ピロリドン、Ｎ−エチル−２−ピロリドン、Ｎ−ヒドロキシメチル−２−ピロリドン、Ｎ−ヒドロキシエチル−２−ピロリドン等のラクタム類；β−プロピオラクトン、γ−ブチロラクトン、γ−バレロラクトン、δ−バレロラクトン、γ−カプロラクトン、ε−カプロラクトン等のラクトン類；１，３−ジメチル−２−イミダゾリジノン、１，３−ジエチル−２−イミダゾリジノン、１，３−ジイソプロピル−２−イミダゾリジノン等のイミダゾリジノン類；等を挙げることができる。これらは１種を用いてもよく、２種以上を混合して用いてもよい。
【００３４】
また、本発明に係る下層膜形成材料には、架橋剤が含まれていてもよく、そのような架橋剤は、本発明に用いる樹脂成分を架橋させることができれば特に限定するものではないが、アミノ基および／またはイミノ基を有する含窒素化合物であって、この含窒素化合物中に存在する全てのアミノ基および／またはイミノ基において、少なくとも２つの水素原子がヒドロキシアルキル基および／またはアルコキシアルキル基で置換された含窒素化合物が好ましい。
【００３５】
前記置換基の数は、含窒素化合物中、２以上、実質的には６以下とされる。
【００３６】
具体的には、例えば、メラミン系化合物、尿素系化合物、グアナミン系化合物、アセトグアナミン系化合物、ベンゾグアナミン系化合物、グリコールウリル系化合物、スクジニルアミド系化合物、エチレン尿素系化合物等において、アミノ基および／またはイミノ基の２つ以上の水素原子が、メチロール基またはアルコキシメチル基あるいはその両方で置換された化合物等を挙げることができる。
【００３７】
これらの含窒素化合物は、例えば、上記メラミン系化合物、尿素系化合物、グアナミン系化合物、アセトグアナミン系化合物、ベンゾグアナミン系化合物、グリコールウリル系化合物、スクシニルアミド系化合物、エチレン尿素系化合物等を、沸騰水中においてホルマリンと反応させてメチロール化することにより、あるいはこれにさらに低級アルコール、具体的にはメタノール、エタノール、ｎ−プロパノール、イソプロパノール、ｎ−ブタノール、イソブタノール等と反応させてアルコキシル化することにより、得ることができる。
【００３８】
また、前記架橋剤として、前記ヒドロキシアルキル基および／またはアルコキシアルキル基と、モノヒドロキシモノカルボン酸との縮合反応物を用いれば、レジストパターン下部の形状改善（フッティングの防止）効果が得られるので、好ましい。
【００３９】
前記モノヒドロキシモノカルボン酸としては、水酸基とカルボキシル基が、同一の炭素原子、または隣接する二つの炭素原子のそれぞれに結合しているものが、フッティング防止の点から好ましい。
【００４０】
また、モノヒドロキシモノカルボン酸との縮合反応物を用いる場合は、縮合前の架橋剤１モルに対して、０．０１〜６モル、好ましくは０．１〜５モルの割合で、モノヒドロキシカルボン酸を縮合反応して得られる反応物を用いることが、フッティング防止効果を得る点から好ましい。この縮合反応は慣用の方法によって行うことができる。
【００４１】
なお、本発明において、前記架橋剤は、１種で用いてもよいし、２種以上を混合して用いてもよい。
【００４２】
さらに、本発明に係る下層膜形成材料には、高吸光性成分、酸性化合物、界面活性剤を、必要に応じて、添加可能である。
【００４３】
前記高吸光性成分の添加効果は、露光光の吸収特性がさらに向上する点にある。この高吸光性成分としては、ホトレジスト層に照射される露光光に対して高い吸収特性を有し、露光光の基板からの反射によって生じる定在波や基板表面の段差による乱反射を防止できるものであればよく、特に制限はない。このようなものとして、例えば、サリシレート系化合物、ベンゾフェノン系化合物、ベンゾトリアゾール系化合物、シアノアクリレート系化合物、アゾ系化合物、ポリエン系化合物、アントラキノン系化合物、スルホン系化合物（好ましくは、ビスフェニルスルホン系化合物）、スルホキシド系化合物（ビスフェニルスルホキシド系化合物）、アントラセン系化合物等、いずれも使用することができる。これらの１種を用いてもよいし、２種以上を混合して用いてもよい。
【００４４】
なかでも、水酸基、ヒドロキシアルキル基、アルコキシアルキル基、およびカルボキシル基の中から選ばれる少なくとも１つの置換基を有する、アントラセン系化合物、ビスフェニルスルホン系化合物、ビスフェニルスルホキシド系化合物およびベンゾフェノン系化合物は、吸収特性が高いので、これらの中から選ばれる少なくとも１種を用いることが、好ましい。これらの中で特に好ましいのは、例えば、アントラセン系化合物またはビスフェニルスルホン系化合物である。これらは単独で用いてもよいし、２種以上を組み合わせて用いてもよい。
【００４５】
前記酸性化合物の添加効果は、フッティングの防止特性が向上する点にある。このような酸性化合物としては、硫黄含有酸残基を持つ無機酸、有機酸またはそれらのエステル等や、活性光線により酸を発生する化合物（酸発生剤、例えばオニウム塩）等を挙げることができる。この酸性化合物を配合する場合の配合量は、全固形分１００質量部に対して３０質量部、好ましくは２０質量部を上限として配合する。あまり少ないと添加効果が得られないが、前記上限値を超えるとレジストパターンの下部にくい込みを生じるおそれがでてくる。
【００４６】
前記界面活性剤の添加効果は、下層膜材料の塗布性の向上である。このような界面活性剤としては、例えば、サーフロンＳＣ−１０３、ＳＲ−１００（以上、旭硝子株式会社製）、ＥＦ−３５１（東北肥料株式会社製）、フロラードＦｃ−４３１、フロラードＦｃ−１３５、フロラードＦｃ−９８、フロラードＦｃ−４３０、フロラードＦｃ−１７６（以上、住友３Ｍ株式会社製）、メガファックＲ−０８（大日本インキ株式会社製）等のフッ素系界面活性剤、を挙げることができる。
【００４７】
この界面活性剤の添加量は、好ましくは、下層膜材料中の全固形分の２００ｐｐｍ未満の範囲で設定する。
【００４８】
次に、本発明に係る配線形成方法を、図１を参照しつつ再度説明する。本発明の配線形成方法では、まず、シリコンウェハなどの基板１ａ上に誘電体層１ｂが積層されてなる半導体基板１上に、前記本発明のリソグラフィー用下層膜形成材料を用いて、下層膜２を形成する（下層膜形成工程（ａ））。
次に、前記下層膜２上にホトレジスト層３を形成し、このホトレジスト層３に露光および現像処理を施して、所定のホトレジストパターン４を形成する（ホトレジストパターン形成工程（ｂ））。
前記ホトレジストパターン４に覆われていない前記下層膜２の露出部分をドライエッチングにより除去する（下層膜パターン化工程（ｃ））。
前記ホトレジストパターン４とパターン化下層膜２とをマスクとして、前記基板１の誘電体層１ｂをエッチングして所定の配線パターン５を形成する（配線パターン形成工程（ｄ））。
前記配線パターン５の形成後の基板１上に残留する前記下層膜２およびホトレジストパターン４をホトレジスト剥離液により同時に除去する（下層膜除去工程（ｅ））。
【００４９】
本発明の配線形成方法は、これら工程（ａ）〜（ｅ）を含むことを特徴とするものである。なお、前記配線パターン５には、例えば、導体材料が埋め込まれることによって、配線層が形成される。また、この方法の説明では、もっとも簡単な配線構造を想定したが、多層の配線層からなり、各上下の配線層がビア配線により電気的に接続されている構造の多層配線構造にももちろん適用できる。本願発明方法の構成は、必要最小限の工程を示したものである。さらに、この方法は、いわゆるダマシンプロセスを想定したものであるが、多層構造を得る場合には、必然的にデュアルダマシンプロセスが採用されることになる。このデュアルダマシンプロセスは、トレンチと呼称される配線溝とビアホールとを連続して形成することが特徴であり、形成順序は、トレンチを先に形成し、続いてビアホールを形成する場合と、逆にビアホールを先に形成し、続いてトレンチを形成する場合とがある。本発明は、そのどちらにも適用可能である。
【００５０】
前記構成の配線形成方法において、前記下層膜除去工程（ｅ）に用いられる前記ホトレジスト剥離液は、少なくとも水溶性アミン、および第４級アンモニウム水酸化物の中から選ばれる少なくとも１種を含有することが好ましい。なかでも好ましく用いられるのは、第４級アンモニウム水酸化物を含有するホトレジスト剥離液である。
【００５１】
前記水溶性アミンとしては、アルカノールアミン、およびアルキルアミンから選ばれる少なくとも１種であることが好ましい。
【００５２】
このようなアミン系剥離液を含有する系の剥離剤には、さらに非アミン系水溶性有機溶剤、水、防食剤、界面活性剤等が配合されてもよい。
【００５３】
前記非アミン系水溶性有機溶剤としては、例えば、ジメチルスルホキシド等のスルホキシド類；ジメチルスルホン、ジエチルスルホン、ビス（２−ヒドロキシエチル）スルホン、テトラメチレンスルホン等のスルホン類；Ｎ，Ｎ−ジメチルホルムアミド、Ｎ−メチルホルムアミド、Ｎ，Ｎ−ジメチルアセトアミド、Ｎ−メチルアセトアミド、Ｎ，Ｎ−ジエチルアセトアミド等のアミド類；Ｎ−メチル−２−ピロリドン、Ｎ−エチル−２−ピロリドン、Ｎ−ヒドロキシメチル−２−ピロリドン、Ｎ−ヒドロキシエチル−２−ピロリドン等のラクタム類；β−プロピオラクトン、γ−ブチロラクトン、γ−バレロラクトン、δ−バレロラクトン、γ−カプロラクトン、ε−カプロラクトン等のラクトン類；１，３−ジメチル−２−イミダゾリジノン、１，３−ジエチル−２−イミダゾリジノン、１，３−ジイソプロピル−２−イミダゾリジノン等のイミダゾリジノン類；エチレングリコール、エチレングリコールモノメチルエーテル、エチレングリコールモノエチルエーテル、エチレングリコールモノブチルエーテル、エチレングリコールモノアセテート、エチレングリコールモノメチルエーテルアセテート、エチレングリコールモノエチルエーテルアセテート、ジエチレングリコール、ジエチレングリコールモノアセテート、ジエチレングリコールモノメチルエーテル、ジエチレングリコールモノエチルエーテル、ジエチ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、プロピレングリコールモノメチルエーテル、ジプロピレングリコールモノメチルエーテル、グリセリン、１，２−ブチレングリコール、１，３−ブチレングリコール、２，３−ブチレングリコール等の多価アルコール類およびその誘導体を挙げることができる。これらは１種を用いてもよく、２種以上を混合して用いてもよい。
【００５４】
また、本発明方法において、前記下層膜の剥離処理に先立って、オゾン水および／または過酸化水素水に接触させる工程を設けても良い。オゾン水は純水中にオゾンガスをバブリング等の手段により溶解させたものを用いるのが好ましい。また、オゾン含有濃度は１ｐｐｍ以上から飽和濃度の間で用いればよく、過酸化水素水は濃度０．１〜６０質量％の水溶液で用いればよい。接触の方法としては、浸漬法、パドル法、シャワー法等が挙げられる。こうした前処理を行うことにより、下層膜およびホトレジスト膜の除去性能を向上させることができる。
【００５５】
本発明方法において、ホトレジスト層を形成するためのホトレジスト組成物は、特に限定されるものではなく、このホトレジスト組成物としては、水銀灯のｉ線、ｇ線、そして、ＫｒＦエキシマレーザー、ＡｒＦエキシマレーザー、さらには、Ｆ_２エキシマレーザー等の露光光に対して通常用いられるホトレジスト組成物を用いることができる。
【００５６】
本発明方法において、露光、現像処理は、通常のリソグラフィーで常用のプロセスを用いることができる。
【００５７】
【実施例】
以下、本発明の実施例を説明する。以下の実施例は、本発明を好適に説明する例示にすぎず、本発明をなんら限定するものではない。
【００５８】
（実施例１〜４）
下層膜形成材料として、次の（Ａ）、（Ｂ）、（Ｃ）、および（Ｄ）の樹脂組成物を調製した。
【００５９】
（Ａ） ｐ−スチレンスルホン酸エチルからなる樹脂成分を、γ−ブチロラクトン／乳酸エチル（２：８）からなる溶媒に溶解し、固形分濃度を６ｗｔ％に調整した樹脂組成物。
【００６０】
（Ｂ） ｐ−スチレンスルホン酸エチル：ヒドロキシエチルアクリレート（＝５：５）からなる樹脂成分と、該樹脂成分量の２０ｗｔ％相当量のサイメル１１７２（三井サイアナミッド社製テトラメチロールグリコールウリル）とを、乳酸エチルからなる溶媒に溶解し、固形分濃度を６ｗｔ％に調整した樹脂組成物。
【００６１】
（Ｃ） ｐ−スチレンスルホン酸エチル／９−ヒドロキシアントラセニルアクリレート（５：５）からなる樹脂成分を、γ−ブチロラクトン／乳酸エチル（２：８）からなる溶媒に溶解し、固形分濃度を６ｗｔ％に調整した樹脂組成物。
【００６２】
（Ｄ） ｐ−スチレンスルホン酸エチル／ヒドロキシエチルアクリレート／９−ヒドロキシアントラセニルアクリレート（４：３：３）からなる樹脂成分と、該樹脂の２０ｗｔ％相当量のサイメル１１７２（三井サイアナミッド株式会社製テトラメチロールグリコールウリル）と、前記２種の固形分量の１０００ｐｐｍ相当量のメガファックＲ０８（大日本インキ株式会社製フッ素系界面活性剤）とを、乳酸エチルからなる溶媒に溶解し、固形分濃度を６ｗｔ％に調整した樹脂組成物。
【００６３】
これら（Ａ）（Ｂ）（Ｃ）（Ｄ）の樹脂組成物を、それぞれ、半導体基板上に塗布し、２００℃にて９０秒間加熱処理し、膜厚２０００Åの下層膜を形成した。
【００６４】
これらの下層膜上にＴＤＵＲ−Ｐ６３０（東京応化工業株式会社製ホトレジスト組成物）を塗布し、１２０℃にて９０秒間加熱処理して、膜厚５０００Åのホトレジスト層を形成した。このホトレジスト層を露光し、順次、露光後加熱（１１０℃、９０秒間）、現像処理を施して、２５０ｎｍのホトレジストパターンを形成した。
【００６５】
前述にようにして得たホトレジストパターンに覆われていない下層膜の露出部分をフルオロカーボン系エッチングガスを用いたドライエッチングにより除去した。前記ホトレジストパターンと、このホトレジストパターン層と同様にパターン化された下層膜とをマスクとして、その下層の基板誘電体層をエッチングして、トレンチもしくはビアホール等の配線構造を形成した。
【００６６】
前述のように配線構造を形成した後、基板を、ジメチルスルホキシドとモノエタノールアミンの混合溶剤（混合比＝７：３）からなる剥離液に１００℃、２０分間浸漬し、ホトレジストパターンと下層膜とを除去した。
【００６７】
下層膜の剥離処理後の各基板表面を走査型顕微鏡にて観察して、それぞれの配線構造パターンの解像性を評価した。その結果、（Ａ）（Ｂ）（Ｃ）（Ｄ）のいずれの下層膜材料を用いた場合でも、寸法制御性に優れた断面形状が良好な矩形のパターンが得られることが確認された。
【００６８】
（実施例５）
前記（Ｃ）の樹脂組成物において、その樹脂成分量の３ｗｔ％相当量の「光酸発生剤であるＴＰＳ−１０９（緑化学株式会社製）」を追加配合して、新たな樹脂組成物（Ｃ２）を調製した。この樹脂組成物（Ｃ２）を用いた以外は前記実施例１と全く同様の手法にて配線構造を形成した。その結果、寸法制御性に優れた矩形のパターンを有する配線構造を得ることができた。
【００６９】
（比較例１）
架橋剤と吸光性成分を主成分とする下層膜材料（東京応化工業社製：商品名ＳＷＫ−ＥＸ３）を半導体基板上に塗布し、２００℃にて９０秒間加熱処理して、膜厚２０００Åの下層膜を形成した。この下層膜上に化学増幅型ホトレジスト組成物（東京応化工業社製：商品名ＴＤＵＲ−Ｐ６３０）を塗布し、１２０℃にて９０秒間加熱処理して、膜厚５０００Åのホトレジスト層を形成した。得られたホトレジスト層に、順次、露光、露光後加熱（１１０℃、９０秒間）、現像処理を施して、２５０ｎｍのホトレジストパターンを形成した。
【００７０】
前述にようにして得たホトレジストパターンに覆われていない下層膜の露出部分をフルオロカーボン系エッチングガスを用いたドライエッチングにより除去した。前記ホトレジストパターンと、このホトレジストパターン層と同様にパターン化された下層膜とをマスクとして、その下層の基板誘電体層をエッチングして、トレンチもしくはビアホール等の配線構造を形成した。
【００７１】
前述のように配線構造を形成した後、基板上に残留しているホトレジストパターンと下層膜とをＯ_２プラズマアッシングにより除去した。
【００７２】
下層膜のアッシング除去処理後のそれぞれの基板表面を走査型顕微鏡にて観察し、それぞれの配線構造パターンの解像性を評価した。その結果、配線構造が形成された誘電体層の表面に腐食が発生しており、その程度は配線層が形成された場合にデバイス特性に支障を来す程度であると推定された。
【００７３】
なお、前記配線構造を形成した直後の基板を、別途、前記実施例にて用いた剥離液に同様の条件にて浸漬してみたが、残留下層膜の除去はできなかった。
【００７４】
【発明の効果】
以上説明したように、本発明のリソグラフィー用下層膜形成材料は、所定のエネルギーが印加されることにより末端基が脱離してスルホン酸残基を生じる置換基を少なくとも有する樹脂成分と、溶媒とを含有していることを特徴とするものである。かかる構成において、前記樹脂成分は、少なくとも下記一般式（１）
【化５】

（式中、ｎは１以上の整数を表し、Ｘは炭素原子数１〜１０の直鎖もしくは分岐状のアルキル鎖、芳香性もしくは脂環性の環状アルキル鎖、アルキルエステル鎖であり、Ｙは所定のエネルギーの印加を受けてスルホン酸残基を生じる置換基である。）
で表される繰り返し単位を有するものが好ましい。
【００７５】
係る構成によって、本発明は、以下の効果を得ることができる。
（１） 本発明の下層膜形成用材料は、ホトレジスト現像液に対して不溶である。そのため、現像液による除去が可能な下層膜において避けがたく生じる除去部分側壁のサイドエッチングや裾引きに起因する寸法制御性の劣化は、問題とならない。
（２） ホトレジスト剥離液により除去可能であるため、誘電率（ｋ）が３．０以下の低誘電体材料のようなＯ_２アッシングプラズマ耐性が低い材料を積層した半導体基板におけるリソグラフィプロセスに用いる下層膜材料として、好適である。
（３） さらには、リソグラフィーの不良により基板を再生する必要が生じた場合、基板にダメージを与えることの少ないウェット処理により下層膜を容易に除去できるので、基板再生のリワーク処理を確実かつ容易に行うことができる。
【図面の簡単な説明】
【図１】本発明の下層膜形成材料を用いた配線形成方法を説明するためのもので、（ａ）〜（ｅ）はリソグラフィーを用いた配線構造形成の工程図である。
【符号の説明】
１ 半導体基板
１ａ 基板
１ｂ 誘電体層
２ 下層膜
３ ホトレジスト層
４ ホトレジストパターン
５ 配線構造[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention prevents the reflected light of the exposure light from the substrate surface from being incident on the photoresist at the time of patterning the photoresist by forming the photoresist layer on the substrate before forming the photoresist pattern on the substrate, thereby forming a photoresist pattern. The present invention relates to a material for forming an underlayer film capable of improving resolution and a wiring forming method using the material for forming a lower film for lithography. More specifically, the present invention provides an underlayer film for lithography that not only has excellent antireflection properties, but also is easy to remove after use, and has no adverse effect on the substrate due to the removal process, thereby enabling a rework process of the substrate. And a wiring forming method using the same.
[0002]
[Prior art]
As is well known, a semiconductor substrate is formed by laminating at least a dielectric layer (insulator layer) on a substrate such as a silicon wafer, and a conductor layer (wiring) patterned in the dielectric layer of the semiconductor substrate. The formation of the layer) forms a semiconductor wiring structure.
[0003]
There are roughly two methods for forming the wiring layer. In the first method, a conductor layer is uniformly formed on the dielectric layer, a photoresist is formed on the conductor layer, and the photoresist is irradiated (exposed) with pattern light and developed to form a resist pattern. Using the resist pattern as a mask, the conductor layer is patterned by etching to form a wiring layer, and a dielectric layer is further laminated thereon to form a wiring layer in the dielectric layer. .
[0004]
In the second method, a photoresist pattern is formed on the dielectric layer, and a wiring groove (trench) is formed in the dielectric layer by etching using the resist pattern as a mask. By embedding a conductor material and laminating a dielectric layer thereon, a semiconductor wiring structure is formed.
[0005]
When the wiring structure is multilayered, a plurality of wiring layers are laminated by repeating the wiring layer forming step in each of the above methods. However, a via wiring forming step is required between each wiring layer forming step. It becomes. In the via wiring forming step, a via hole is formed in a dielectric layer serving as an interlayer insulating layer between the lower wiring layer and the upper wiring layer, and a conductor material is deposited or embedded in the via hole by a vapor phase method. This is a step of forming a via wiring for electrically connecting the lower wiring layer and the upper wiring layer.
[0006]
In any of the above two wiring forming methods, when exposing and patterning the photoresist layer, the exposure light passes through the resist layer, the transmitted light is reflected on the lower layer surface, and the reflected light is exposed on the photoresist layer. A phenomenon occurs in which the light should enter a part that should not be used. The incidence of the reflected light on the photoresist layer deteriorates the pattern resolution of the photoresist. Therefore, before forming a photoresist layer on a semiconductor substrate, a resin composition containing a material having a property of absorbing exposure light is conventionally applied on the substrate to form an underlayer film. A method of forming a photoresist layer has been adopted. This lower layer film is also called an anti-reflection film because of its intended function.
[0007]
Conventionally, various materials have been proposed as materials for the antireflection film. For example, a resin composition containing a polymer having an iminosulfonate group and a solvent has been proposed (Patent Document 1).
[0008]
Further, a light-absorbing polymer containing a polymer having a hydroxystyrene unit having a specific substituent including a sulfonic acid ester has been developed (Patent Document 2), and the light-absorbing polymer and the solvent are contained. An anti-reflection film forming material has been proposed (Patent Document 3).
[0009]
By the way, in addition to the main purpose anti-reflection property, the lower layer film having the anti-reflection property of the exposure light, by using a photoresist pattern as a mask, after the etching process of the lower conductive layer or the dielectric layer is completed, by some means A characteristic that can be removed is required.
[0010]
From the viewpoint of removing the underlayer film after serving as an antireflection film, when examining the conventional underlayer film, first, the antireflection film material disclosed in Patent Document 1 is: As the resin component, a polymer having an iminosulfonate group is used, and this resin component is insoluble in a photoresist stripping solution. Therefore, according to the technology disclosed in Patent Document 1, after removing the upper photoresist pattern with a stripping solution, the remaining lower film is removed by O₂It has been removed by plasma ashing.
[0011]
Further, the resin components disclosed in Patent Documents 2 and 3 are also insoluble in a photoresist stripping solution, and after removing the photoresist pattern with the stripping solution, the remaining lower layer film is removed.₂Removed by plasma ashing.
[0012]
[Patent Document 1]
JP-A-10-319601
[Patent Document 2]
JP 2000-512336 A
[Patent Document 3]
JP 2000-512402 A
[0013]
[Problems to be solved by the invention]
As is well known, in a semiconductor wiring structure, a dielectric layer covering a wiring layer and electrically isolating it from other wiring layers does not affect the electrical characteristics of the wiring layer. It is necessary that the dielectric constant be as low as possible. As for the degree of low dielectric constant of the dielectric, specifically, those having a dielectric constant k of 3.0 or less are becoming mainstream. However, such a low dielectric constant material is O₂Low resistance to plasma ashing, O₂Exposure to plasma readily degrades the surface and increases the dielectric constant.
[0014]
When the conventional anti-reflection film is formed on a semiconductor substrate using such a low dielectric layer, and a wiring layer is formed, the anti-reflection film used to remove the anti-reflection film is used.₂Deterioration in which the dielectric layer is eroded or its dielectric constant is increased by plasma ashing is likely to occur, and as a result, there is a problem that the electrical characteristics of the wiring layer are adversely affected.
[0015]
In the manufacture of a semiconductor wiring structure, as described above, in order to form a wiring layer on a semiconductor by etching or to form a wiring groove for embedding a wiring layer, patterning by lithography of a photoresist or an underlying film is performed. Done. The control factors of this lithography process include controlling the current value and voltage value in a stepper that generates exposure light, adjusting the focal position of a lens, the accuracy of a photomask, the accuracy of a mounting position, and the coating characteristics and the like of a photoresist composition. There are many factors such as curing characteristics, and these control factors fluctuate for some reason, resulting in poor patterning and the need to repeat the lithography process. In such a case, discarding the semiconductor substrate and using a new semiconductor substrate is a waste of resources and has an adverse effect on the environment. Therefore, in such a manufacturing process, it is necessary to recover the semiconductor substrate by removing the photoresist layer and the lower layer film on which insufficient lithography has been performed. Such a process of removing the lower layer film in the process of regenerating and collecting the semiconductor substrate is called a rework process, and is an important process when considering the economics of manufacturing a semiconductor wiring structure. Considering the conventional anti-reflection film from the viewpoint of such rework processing, the conventional anti-reflection film has₂Since plasma ashing must be used, there is a problem that the characteristics of the semiconductor substrate after the rework process are easily deteriorated, which is not appropriate.
[0016]
The present invention has been made in view of the problems in the conventional underlayer film material, and has high exposure light absorption, excellent resistance to a 2.38 wt% TMAH developer usually used in a photoresist development process, It is an object of the present invention to provide an underlayer film material that can be removed with a photoresist stripper and that facilitates rework processing of a substrate. Another object of the present invention is to provide a method for forming a wiring using the material for the lower layer film.
[0017]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above-mentioned conventional problems, and as a result, when a predetermined energy is applied, a terminal group is eliminated to form a substituent that generates a sulfonic acid residue. It has been found that when the underlayer film material is constituted by containing at least the resin as a resin component, good functions and effects can be obtained.
[0018]
That is, the underlayer film formed using the underlayer film material as described above has a high resistance to a 2.38 wt% TMAH developer for developing the photoresist layer after exposure, and is formed by applying a predetermined energy. Some of the terminal groups of the resin component of the lower layer film thus formed are sulfonated, and have compatibility with water-soluble amines and quaternary ammonium hydroxides. Since the solution containing these water-soluble amines and quaternary ammonium hydroxides can be used for a photoresist stripping solution, the underlayer film can be simultaneously stripped by a photoresist stripping process.
[0019]
As described above, the present inventors have determined that “a lower layer film material containing, as a resin component, a resin having at least a substituent whose terminal group is eliminated by application of predetermined energy to generate a sulfonic acid residue”. The formed lower layer film has high resistance to a 2.38 wt% TMAH developer usually used in a photoresist developing process, so that it does not deteriorate during resist development and can be easily removed with a photoresist stripping solution. It has been found that not only the simplification can be performed, but also that the removal processing does not deteriorate the dielectric layer of the substrate.
[0020]
That is, the material for forming an underlayer film for lithography according to the present invention is a material for forming an underlayer film provided on a semiconductor substrate before forming a photoresist for wiring formation patterning on the substrate, and has a predetermined energy. It is characterized by containing a solvent and a resin component having at least a substituent which generates a sulfonic acid residue by elimination of a terminal group when applied.
[0021]
Further, the wiring forming method according to the present invention includes a lower film forming step of forming a lower film on a substrate by using the lower film forming material for lithography, and forming a photoresist layer on the lower film, Exposure and development treatment on the layer, a photoresist pattern forming step of forming a predetermined photoresist pattern, and an underlayer film patterning step of removing the exposed portion of the underlayer film that is not covered by the photoresist pattern by dry etching, A wiring pattern forming step of etching the substrate to form a predetermined wiring pattern using the photoresist pattern and the patterned lower film as a mask, and forming the lower film and the photoresist pattern remaining on the substrate after the formation of the wiring pattern. Removing the lower layer film simultaneously with a photoresist stripper. It is characterized in.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
The underlayer film forming material of the present invention contains, as described above, a resin component having at least a substituent from which a terminal group is eliminated by application of predetermined energy to generate a sulfonic acid residue, and a solvent. It is characterized by having.
[0023]
In such a configuration, the resin component has at least the following general formula (1)
Embedded image

(In the formula, n represents an integer of 1 or more, X is a linear or branched alkyl chain having 1 to 10 carbon atoms, an aromatic or alicyclic alkyl chain, an alkyl ester chain, and Y is A substituent that generates a sulfonic acid residue upon application of predetermined energy.)
It has a repeating unit represented by these.
[0024]
As the predetermined energy applied to generate the sulfonic acid residue, for example, a sulfonic acid residue can be generated by heat treatment at 80 ° C. or more. Such application of the predetermined energy is further promoted by the concerted action of heating and alkali in the peeling treatment.
[0025]
As the substituent Y in the general formula (1), -SO₃R₁Or -SO₃ ⁻R₂ ⁺(Where R₁And R₂Is preferably a monovalent organic group).
[0026]
The organic group R₁Is preferably one selected from an alkyl group having 1 to 10 carbon atoms or a hydroxyalkyl group.
[0027]
Further, the organic group R₂Is preferably at least one selected from alkanolamines and alkylamines.
[0028]
Further, as a resin component having at least a substituent that generates a sulfonic acid residue by elimination of a terminal group by application of the predetermined energy, any of the resin components described above, acrylic acid or methacrylic acid or A copolymer with a derivative of the above or a mixed resin may be used.
[0029]
When the copolymer or the mixed resin is used as the resin component, the polymerization ratio or the mixing ratio is within a range that is resistant to a 2.38 wt% TMAH developer and can be removed by a resist stripper. There is no particular limitation.
[0030]
Furthermore, as a resin component having at least a substituent that generates a sulfonic acid residue by removing a terminal group by applying the predetermined energy,
For a copolymer or mixed resin of any one of the above resin components and acrylic acid or methacrylic acid or a derivative thereof, the following general formula (2)
Embedded image

(Wherein, n represents an integer of 1 or more;₃Is at least one selected from a hydrogen atom, a fluorine atom, a hydroxyl group, a carboxyl group, a hydroxyalkyl group having 1 to 5 carbon atoms and an alkoxyalkyl group having 1 to 5 carbon atoms, and Z represents 1 carbon atom. And 10 to 10 linear or branched alkyl chains, aromatic or alicyclic alkyl chains, and alkyl ester chains. )
A resin component composed of a copolymer obtained by copolymerizing a repeating unit represented by formula (1) or a mixed resin obtained by mixing a resin compound having a repeating unit represented by formula (2) may be used.
[0031]
If a copolymer is prepared using the derivative of the general formula (2) and the copolymer is used as a resin component to constitute a lower layer material, anthracene is contained in the resin component unit. Particularly, in lithography using a KrF excimer laser, absorption characteristics are high, which is preferable.
[0032]
The solvent used for the lower layer film forming material of the present invention can be used without any particular limitation as long as it is used for a conventional lower layer film forming material.
[0033]
Specifically, for example, ketones such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, 1,1,1-trimethyl acetone; ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl Ether, ethylene glycol monobutyl ether, ethylene glycol monoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol, diethylene glycol monoacetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol, propylene glycol monomethyl D Polyhydric alcohols such as ter, dipropylene glycol monomethyl ether, glycerin, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol and derivatives thereof; cyclic ethers such as dioxane; ethyl lactate Esters such as methyl acetate, ethyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate and ethyl 3-ethoxypropionate; sulfoxides such as dimethyl sulfoxide; dimethyl sulfone, diethyl sulfone, bis Sulfones such as (2-hydroxyethyl) sulfone and tetramethylene sulfone; N, N-dimethylformamide, N-methylformamide, N, N-dimethylacetamide, N-methylacetamide, N, N-diethylacetamide Lactams such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-hydroxymethyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone; β-propiolactone, γ- Lactones such as butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone; 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, Imidazolidinones such as 3-diisopropyl-2-imidazolidinone; and the like. These may be used alone or in combination of two or more.
[0034]
The underlayer film forming material according to the present invention may contain a crosslinking agent, and such a crosslinking agent is not particularly limited as long as the resin component used in the present invention can be crosslinked. A nitrogen-containing compound having an amino group and / or an imino group, wherein at least two hydrogen atoms in all the amino groups and / or imino groups present in the nitrogen-containing compound are a hydroxyalkyl group and / or an alkoxyalkyl group Is preferred.
[0035]
The number of the substituents is 2 or more, substantially 6 or less in the nitrogen-containing compound.
[0036]
Specifically, for example, in a melamine-based compound, a urea-based compound, a guanamine-based compound, an acetoguanamine-based compound, a benzoguanamine-based compound, a glycoluril-based compound, a sucdinylamide-based compound, an ethylene urea-based compound, an amino group and / or an imino Compounds in which two or more hydrogen atoms of the group are substituted with a methylol group, an alkoxymethyl group, or both are exemplified.
[0037]
These nitrogen-containing compounds include, for example, the above melamine compounds, urea compounds, guanamine compounds, acetoguanamine compounds, benzoguanamine compounds, glycoluril compounds, succinylamide compounds, ethylene urea compounds, etc., in boiling water. By reacting with formalin to form a methylol, or by further reacting with a lower alcohol, specifically methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, etc. Obtainable.
[0038]
When a condensation reaction product of the hydroxyalkyl group and / or alkoxyalkyl group and monohydroxymonocarboxylic acid is used as the cross-linking agent, an effect of improving the shape of the lower part of the resist pattern (preventing footing) can be obtained. ,preferable.
[0039]
As the monohydroxymonocarboxylic acid, those in which a hydroxyl group and a carboxyl group are bonded to the same carbon atom or two adjacent carbon atoms are preferable from the viewpoint of preventing footing.
[0040]
When a condensation reaction product with a monohydroxymonocarboxylic acid is used, the amount of the monohydroxycarboxylic acid is 0.01 to 6 mol, preferably 0.1 to 5 mol, per 1 mol of the crosslinking agent before condensation. It is preferable to use a reaction product obtained by condensing an acid to obtain an effect of preventing footing. This condensation reaction can be performed by a conventional method.
[0041]
In the present invention, the crosslinking agent may be used alone, or two or more kinds may be used as a mixture.
[0042]
Further, a high light-absorbing component, an acidic compound, and a surfactant can be added to the underlayer film forming material according to the present invention, if necessary.
[0043]
The effect of the addition of the high light-absorbing component is that the absorption characteristics of exposure light are further improved. The high light-absorbing component has a high absorption characteristic with respect to exposure light irradiated to the photoresist layer, and can prevent a standing wave caused by the reflection of the exposure light from the substrate and irregular reflection due to a step on the substrate surface. There is no particular limitation. Such compounds include, for example, salicylate compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, azo compounds, polyene compounds, anthraquinone compounds, and sulfone compounds (preferably bisphenylsulfone compounds). ), Sulfoxide compounds (bisphenylsulfoxide compounds), anthracene compounds, and the like. One of these may be used, or a mixture of two or more thereof may be used.
[0044]
Among them, an anthracene compound, a bisphenylsulfone compound, a bisphenylsulfoxide compound and a benzophenone compound having at least one substituent selected from a hydroxyl group, a hydroxyalkyl group, an alkoxyalkyl group, and a carboxyl group, It is preferable to use at least one selected from these, because of its high absorption characteristics. Of these, particularly preferred are, for example, anthracene-based compounds and bisphenylsulfone-based compounds. These may be used alone or in combination of two or more.
[0045]
The effect of the addition of the acidic compound is that the property of preventing footing is improved. Examples of such an acidic compound include an inorganic acid having a sulfur-containing acid residue, an organic acid or an ester thereof, and a compound capable of generating an acid by actinic rays (an acid generator such as an onium salt). . When this acidic compound is compounded, the compounding amount is 30 parts by mass, preferably 20 parts by mass, based on 100 parts by mass of the total solid content. If the amount is too small, the effect of addition cannot be obtained, but if it exceeds the above upper limit, there is a possibility that the lower part of the resist pattern may be formed.
[0046]
The effect of the addition of the surfactant is an improvement in the applicability of the underlayer film material. Examples of such a surfactant include Surflon SC-103, SR-100 (all manufactured by Asahi Glass Co., Ltd.), EF-351 (manufactured by Tohoku Fertilizer Co., Ltd.), Florad Fc-431, Florad Fc-135, and Florard. Fluorinated surfactants such as Fc-98, Florad Fc-430, Florad Fc-176 (above, manufactured by Sumitomo 3M Co., Ltd.), and Megafac R-08 (manufactured by Dainippon Ink Co., Ltd.).
[0047]
The amount of the surfactant to be added is preferably set within a range of less than 200 ppm of the total solid content in the lower film material.
[0048]
Next, the wiring forming method according to the present invention will be described again with reference to FIG. In the method of forming a wiring according to the present invention, first, a lower film 2 is formed on a semiconductor substrate 1 having a dielectric layer 1b laminated on a substrate 1a such as a silicon wafer by using the lower film forming material for lithography of the present invention. Is formed (underlying film forming step (a)).
Next, a photoresist layer 3 is formed on the lower film 2, and the photoresist layer 3 is exposed and developed to form a predetermined photoresist pattern 4 (photoresist pattern forming step (b)).
The exposed portion of the lower film 2 not covered with the photoresist pattern 4 is removed by dry etching (lower film patterning step (c)).
Using the photoresist pattern 4 and the patterned lower film 2 as a mask, the dielectric layer 1b of the substrate 1 is etched to form a predetermined wiring pattern 5 (wiring pattern forming step (d)).
The lower film 2 and the photoresist pattern 4 remaining on the substrate 1 after the formation of the wiring pattern 5 are simultaneously removed by a photoresist stripper (a lower film removing step (e)).
[0049]
The wiring forming method of the present invention is characterized by including these steps (a) to (e). A wiring layer is formed in the wiring pattern 5 by, for example, embedding a conductive material. In the description of this method, the simplest wiring structure is assumed, but it is of course applicable to a multi-layer wiring structure having a multi-layer wiring layer, and the upper and lower wiring layers are electrically connected by via wiring. it can. The configuration of the method of the present invention shows the minimum necessary steps. Further, this method assumes a so-called damascene process, but when a multilayer structure is obtained, a dual damascene process is necessarily employed. This dual damascene process is characterized in that a wiring groove called a trench and a via hole are continuously formed, and the formation order is opposite to the case where the trench is formed first and then the via hole is formed. In some cases, a via hole is formed first, and then a trench is formed. The present invention is applicable to both of them.
[0050]
In the wiring forming method having the above configuration, the photoresist stripping solution used in the lower layer film removing step (e) contains at least one selected from a water-soluble amine and a quaternary ammonium hydroxide. Is preferred. Of these, a photoresist stripper containing a quaternary ammonium hydroxide is preferably used.
[0051]
The water-soluble amine is preferably at least one selected from alkanolamines and alkylamines.
[0052]
A non-amine-based water-soluble organic solvent, water, an anticorrosive, a surfactant, and the like may be further blended with the system-based release agent containing such an amine-based release solution.
[0053]
Examples of the non-amine water-soluble organic solvent include sulfoxides such as dimethyl sulfoxide; sulfones such as dimethyl sulfone, diethyl sulfone, bis (2-hydroxyethyl) sulfone, and tetramethylene sulfone; N, N-dimethylformamide; Amides such as N-methylformamide, N, N-dimethylacetamide, N-methylacetamide, N, N-diethylacetamide; N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-hydroxymethyl-2 Lactams such as -pyrrolidone, N-hydroxyethyl-2-pyrrolidone; lactones such as β-propiolactone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone; 3-dimethyl-2-imidazolidinone, Imidazolidinones such as 1,3-diethyl-2-imidazolidinone and 1,3-diisopropyl-2-imidazolidinone; ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol Monoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol, diethylene glycol monoacetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, glycerin , , 2-butylene glycol, 1,3-butylene glycol, may be mentioned polyhydric alcohols and derivatives thereof such as 2,3-butylene glycol. These may be used alone or in combination of two or more.
[0054]
Further, in the method of the present invention, a step of contacting with ozone water and / or hydrogen peroxide water may be provided prior to the peeling treatment of the lower layer film. It is preferable to use ozone water obtained by dissolving ozone gas in pure water by means such as bubbling. Further, the ozone content concentration may be used between 1 ppm or more and the saturation concentration, and the hydrogen peroxide solution may be used as an aqueous solution having a concentration of 0.1 to 60% by mass. Examples of the contact method include an immersion method, a paddle method, and a shower method. By performing such a pretreatment, the performance of removing the lower layer film and the photoresist film can be improved.
[0055]
In the method of the present invention, the photoresist composition for forming the photoresist layer is not particularly limited. Examples of the photoresist composition include i-line and g-line of a mercury lamp, and a KrF excimer laser, an ArF excimer laser, Furthermore, F₂A photoresist composition generally used for exposure light such as an excimer laser can be used.
[0056]
In the method of the present invention, the exposure and the development can be carried out by the usual processes in ordinary lithography.
[0057]
【Example】
Hereinafter, examples of the present invention will be described. The following examples are merely exemplifications for suitably describing the present invention, and do not limit the present invention at all.
[0058]
(Examples 1 to 4)
The following resin compositions (A), (B), (C) and (D) were prepared as lower layer film forming materials.
[0059]
(A) A resin composition in which a resin component composed of ethyl p-styrenesulfonate is dissolved in a solvent composed of γ-butyrolactone / ethyl lactate (2: 8) to adjust the solid content to 6 wt%.
[0060]
(B) A resin component composed of ethyl p-styrenesulfonate: hydroxyethyl acrylate (= 5: 5) and Cymel 1172 (tetramethylol glycoluril manufactured by Mitsui Cyanamid Co., Ltd.) in an amount equivalent to 20% by weight of the resin component, A resin composition dissolved in a solvent composed of ethyl lactate and having a solid content adjusted to 6 wt%.
[0061]
(C) A resin component composed of ethyl p-styrenesulfonate / 9-hydroxyanthracenyl acrylate (5: 5) is dissolved in a solvent composed of γ-butyrolactone / ethyl lactate (2: 8), and the solid content concentration is reduced. A resin composition adjusted to 6% by weight.
[0062]
(D) Resin component consisting of ethyl p-styrenesulfonate / hydroxyethyl acrylate / 9-hydroxyanthracenyl acrylate (4: 3: 3) and Cymel 1172 (20% by weight of the resin) (manufactured by Mitsui Cyanamid Co., Ltd.) Tetramethylol glycoluril) and Megafac R08 (a fluorosurfactant manufactured by Dai Nippon Ink Co., Ltd.) in an amount equivalent to 1000 ppm of the two solid contents are dissolved in a solvent composed of ethyl lactate, and the solid content concentration is reduced. A resin composition adjusted to 6% by weight.
[0063]
Each of the resin compositions (A), (B), (C), and (D) was applied on a semiconductor substrate and heat-treated at 200 ° C. for 90 seconds to form a 2000-nm thick lower layer film.
[0064]
TDUR-P630 (photoresist composition manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied on these underlayer films, and heated at 120 ° C. for 90 seconds to form a photoresist layer having a thickness of 5000 °. The photoresist layer was exposed, and then sequentially heated after exposure (110 ° C., 90 seconds) and developed to form a photoresist pattern of 250 nm.
[0065]
The exposed portion of the lower layer film not covered with the photoresist pattern obtained as described above was removed by dry etching using a fluorocarbon-based etching gas. Using the photoresist pattern and the lower layer film patterned similarly to the photoresist pattern layer as a mask, the underlying substrate dielectric layer was etched to form a wiring structure such as a trench or a via hole.
[0066]
After the wiring structure is formed as described above, the substrate is immersed in a stripping solution composed of a mixed solvent of dimethyl sulfoxide and monoethanolamine (mixing ratio = 7: 3) at 100 ° C. for 20 minutes to form a photoresist pattern and an underlayer film. Was removed.
[0067]
The surface of each substrate after the release treatment of the lower layer film was observed with a scanning microscope, and the resolution of each wiring structure pattern was evaluated. As a result, it was confirmed that a rectangular pattern excellent in dimensional controllability and having a good cross-sectional shape was obtained in any of the lower layer film materials (A), (B), (C), and (D).
[0068]
(Example 5)
In the resin composition of (C), "TPS-109 which is a photoacid generator (manufactured by Midori Kagaku Co., Ltd.)" in an amount equivalent to 3 wt% of the resin component is additionally blended, and a new resin composition ( C2) was prepared. A wiring structure was formed in the same manner as in Example 1 except that the resin composition (C2) was used. As a result, a wiring structure having a rectangular pattern excellent in dimensional controllability was obtained.
[0069]
(Comparative Example 1)
An underlayer film material (manufactured by Tokyo Ohka Kogyo Co., Ltd., trade name: SWK-EX3) containing a crosslinking agent and a light-absorbing component as main components is coated on a semiconductor substrate, and heated at 200 ° C. for 90 seconds to form a film having a thickness of 2000 mm A lower layer film was formed. A chemically amplified photoresist composition (trade name: TDUR-P630, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied on the lower layer film, and heated at 120 ° C. for 90 seconds to form a photoresist layer having a thickness of 5000 °. The obtained photoresist layer was sequentially subjected to exposure, post-exposure heating (110 ° C., 90 seconds), and development to form a 250 nm photoresist pattern.
[0070]
The exposed portion of the lower layer film not covered with the photoresist pattern obtained as described above was removed by dry etching using a fluorocarbon-based etching gas. Using the photoresist pattern and the lower layer film patterned similarly to the photoresist pattern layer as a mask, the underlying substrate dielectric layer was etched to form a wiring structure such as a trench or a via hole.
[0071]
After forming the wiring structure as described above, the photoresist pattern remaining on the substrate and the underlying film are₂It was removed by plasma ashing.
[0072]
The surface of each substrate after the ashing removal treatment of the lower layer film was observed with a scanning microscope, and the resolution of each wiring structure pattern was evaluated. As a result, it was presumed that corrosion occurred on the surface of the dielectric layer on which the wiring structure was formed, and the degree of the corrosion was such that the device characteristics would not be affected when the wiring layer was formed.
[0073]
The substrate immediately after the formation of the wiring structure was separately immersed in the stripping solution used in the above example under the same conditions, but the residual underlayer film could not be removed.
[0074]
【The invention's effect】
As described above, the material for forming an underlayer film for lithography of the present invention comprises a resin component having at least a substituent capable of forming a sulfonic acid residue by elimination of a terminal group by application of predetermined energy, and a solvent. It is characterized by containing. In such a configuration, the resin component has at least the following general formula (1)
Embedded image

(In the formula, n represents an integer of 1 or more, X is a linear or branched alkyl chain having 1 to 10 carbon atoms, an aromatic or alicyclic alkyl chain, an alkyl ester chain, and Y is A substituent that generates a sulfonic acid residue upon application of predetermined energy.)
What has a repeating unit represented by these is preferable.
[0075]
With such a configuration, the present invention can obtain the following effects.
(1) The material for forming an underlayer film of the present invention is insoluble in a photoresist developer. Therefore, deterioration of dimensional controllability due to side etching or skirting of the side wall of the removed portion which is unavoidable in the lower layer film which can be removed by the developer does not pose a problem.
(2) Since it can be removed by a photoresist stripping solution, the dielectric constant (k) of O such as a low dielectric material having a dielectric constant (k) of 3.0 or less is low.₂It is suitable as a lower layer material used in a lithography process on a semiconductor substrate on which a material having low ashing plasma resistance is laminated.
(3) Further, when it becomes necessary to regenerate the substrate due to lithography failure, the lower layer film can be easily removed by a wet process that does not damage the substrate, so that the rework process for substrate regeneration can be performed reliably and easily. It can be carried out.
[Brief description of the drawings]
FIGS. 1A to 1E are views for explaining a wiring forming method using a lower layer film forming material according to the present invention, wherein FIGS.
[Explanation of symbols]
1 semiconductor substrate
1a Substrate
1b Dielectric layer
2 Lower layer film
3 Photoresist layer
4 Photoresist pattern
5 Wiring structure

Claims (12)

A material for forming a lower layer film provided on the substrate before forming a photoresist for wiring formation patterning on a semiconductor substrate,
A material for forming an underlayer film for lithography, comprising: a resin component having at least a substituent generating a sulfonic acid residue by the elimination of a terminal group by application of a predetermined energy; and a solvent. The resin component has at least the following general formula (1)

(In the formula, n represents an integer of 1 or more, X is a linear or branched alkyl chain having 1 to 10 carbon atoms, an aromatic or alicyclic alkyl chain, an alkyl ester chain, and Y is A substituent that generates a sulfonic acid residue upon application of predetermined energy.)
The material for forming an underlayer film for lithography according to claim 1, comprising a repeating unit represented by the following formula: The lower layer film forming material for lithography according to claim 1, wherein the predetermined energy applied to generate the sulfonic acid residue is heat of 80 ° C or more. Formula (1) substituent Y is _-SO 3 _{R 1} or _-SO ³ - (wherein, _{R 1} and _{R 2} is a monovalent organic group) _R ^{2 +} claims, characterized in that a 2 Or the material for forming a lower layer film for lithography according to item 3. The organic group R ₁ is, the lower layer material for lithography according to claim 4, characterized in that the one selected from among alkyl or hydroxyalkyl group, having 1 to 10 carbon atoms. The organic group R ₂ is, underlayer film forming material for lithography according to claim 4, wherein the at least one selected from alkanolamines, and alkylamines. The resin component having at least a substituent from which a terminal group is eliminated by application of the predetermined energy to generate a sulfonic acid residue, the resin component according to any one of claims 3 to 6, and an acrylic resin. 3. The material for forming an underlayer film for lithography according to claim 1, wherein the material is a copolymer or a mixed resin with an acid or methacrylic acid or a derivative thereof. A resin component having at least a substituent that generates a sulfonic acid residue by elimination of a terminal group when the predetermined energy is applied,
A copolymer or a mixed resin of the resin component according to any one of claims 3 to 6 with acrylic acid, methacrylic acid, or a derivative thereof, has the following general formula (2):

(In the formula, n represents an integer of 1 or more, and R ₃ represents a hydrogen atom, a fluorine atom, a hydroxyl group, a carboxyl group, a hydroxyalkyl group having 1 to 5 carbon atoms, or an alkoxyalkyl group having 1 to 5 carbon atoms. And Z is a linear or branched alkyl chain having 1 to 10 carbon atoms, an aromatic or alicyclic alkyl chain, or an alkyl ester chain.)
A resin component comprising a copolymer obtained by copolymerizing a repeating unit represented by formula (1) or a mixed resin obtained by mixing a resin compound having a repeating unit represented by formula (2). 3. The material for forming an underlayer film for lithography according to 1 or 2. The lower layer film forming material for lithography according to any one of claims 1 to 8, further comprising a crosslinking agent. An underlayer film forming step of forming an underlayer film on a substrate using the lithography underlayer film forming material according to any one of claims 1 to 9,
Forming a photoresist layer on the lower film, exposing and developing the photoresist layer, a photoresist pattern forming step of forming a predetermined photoresist pattern,
An underlayer film patterning step of removing an exposed portion of the underlayer film that is not covered with the photoresist pattern by dry etching,
A wiring pattern forming step of forming a predetermined wiring pattern by etching the substrate using the photoresist pattern and the patterned lower layer film as a mask,
An underlayer film removing step of simultaneously removing the underlayer film and the photoresist pattern remaining on the substrate after the formation of the wiring pattern by a photoresist stripper,
A wiring forming method, comprising: The wiring formation according to claim 10, wherein the photoresist stripping solution used in the lower layer film removing step contains at least one selected from a water-soluble amine and a quaternary ammonium hydroxide. Method. The method according to claim 11, wherein the water-soluble amine is at least one selected from alkanolamines and alkylamines.

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