JP3965434B2 - Reaction development image forming method - Google Patents

Description

この表において左にある結合ほど求核攻撃を受けやすい（不安定である）ことを示す。この表から、イミド結合は比較的不安定でありアミンの攻撃を受けやすい。即ち、特にアミンに工夫をしなくとも容易に求核置換反応を起こすことが出来る。しかるに、カーボナート、エステル、ウレタン又はアミドの各結合は比較的安定でありアミンの攻撃を受けにくくなっている。即ち、用いるアミンにより強い求核性を持たせる工夫をしなければ、求核置換反応を起こすことが困難になっている。このような求核反応に対する安定性の高い結合を破壊することが出来るのが本発明の反応現像画像形成法の特徴の一つである。即ち、本発明の反応現像画像形成法はカーボナート、エステル、ウレタン又はアミドなどの求核試剤との反応性が低い結合を有する樹脂をフォトレジストの対象として用いることを可能としたところに特徴があるともいえる。
【００１１】
また、本発明の反応現像画像形成法が好ましく適用できるポリマーは、特にその側鎖などに、塩基と反応可能な官能基（例えばカルボキシル基やフェノール性水酸基など）や、あるいは酸や塩基により反応してカルボキシル基やフェノール性水酸基を発生できるような反応性基（保護基と結合したエステルあるいはフェノール型エーテルなど）などを有する必要が無いことが特徴である。
【００１２】
一方、アミンは、非共有電子対を有する窒素原子を有する化合物であり、有機アミン（アミノ酸を含む）と無機アミンに分類される。これらは求核性を有する化合物であり、光酸発生剤により生ずる酸によって、極性の増大した露光域のポリマー中のヘテロ原子に結合したカルボニル基に求核的に反応する。
但し、求核性でないと考えられるアミンであっても、現像条件、特に溶媒の設定によってはカルボニル基に求核的に反応する場合がある。例えば、テトラメチルアンモニウム水酸化物（ＴＭＡＨ）は通常条件では求核性でないため本発明の反応現像画像形成法には好ましいアミンとはいえないが、アルコール／Ｎ−メチル−２−ピロリドン(以下、ＮＭＰという。)のような水を含まない系やあるいは少量の水しか含まないような溶媒系では、ＴＭＡＨのＯＨアニオンは水があると求核性が大きく低下するので、水の代わりにアルコールあるいはアルコールも含まない有機溶媒／ＮＭＰのような系ではカルボニル基への反応性が高くなると考えられる。
アミンの塩基性は酸性度指数（ｐＫ_ａ）が大きいほど強いが、本発明の反応現像画像形成法においては塩基性よりもカルボニル基（Ｃ＝Ｏ）のＣ原子に対する反応性（求核性）が重要であり、それは分子サイズの小さいほど強いと考えられる。従って、一般にＮ原子に大きな炭素鎖が結合した有機アミンよりも無機アミンのほうが求核性が強く、本発明の反応現像画像形成法に適している。本発明の求核性アミンの具体例を酸解離定数とともに下表に列挙する。
【００１３】
【表２】

好ましいアミンとしては、表１に記載のヒドロキシルアミン、ヒドラジン、及びアンモニアの無機アミン、並びに、Ｎ，Ｎ−ジメチルエタノールアミン、Ｎ−メチルエタノールアミン、エタノールアミン、Ｎ−メチルモルホリン、メチルアミン、エチルアミン、ｎ−プロピルアミン、ｎ−ブチルアミン、ベンジルアミン、シクロヘキシルアミン、エチレンジアミン、及びモルホリン、並びにグリシンやβ−アラニンなどのアミノ酸等の有機アミンが挙げられる。
無機アミンは有機アミンに比べて防爆設備を必要とせず環境負荷が小さいなどの利点がある。
本発明の方法においては、最も求核性アミンの求核攻撃を受けやすい（安定性の低い）結合であるイミド結合を有するポリマーと、求核性の強い無機アミンを用いることが最も好ましい組み合わせといえる。
【００１４】
【発明の実施の形態】
本発明のポジ型フォトレジスト中に存在する光酸発生剤は化学放射線の照射により酸を発生する化合物であり、キノンジアジド化合物，オニウム塩、スルホン酸エステル類、有機ハロゲン化合物等が使用される。特にキノンジアジド化合物は１，２−ナフトキノン−２−ジアジド−５−スルホン酸又は１，２−ナフトキノン−２−ジアジド−４−スルホン酸と低分子芳香族ヒドロキノン化合物、例えば２，３，４−トリヒドロキシベンゾフェノンや２，３，４，４’−テトラヒドロキシベンゾフェノン及びトリヒドロキシベンゼン、例えば１，３，５−トリヒドロキシベンゼン、又はクレゾールのエステル生成化合物である。オニウム塩としては、トリフェニルスルホニウムヘキサフルオロアンチモネート、トリフェニルスルホニウムヘキサフルオロホスフェート等がある。これらは安息香酸ｔ−ブチルなどのエステルと一緒に使用される。これらの中で、特に、１，２−ナフトキノン−２−ジアジド−５−スルホン酸−ｐ−クレゾールエステルが好ましい。光酸発生剤はフォトレジスト中に全固形含量に基づいて５〜５０重量％、好ましくは１０〜４０重量％、より好ましくは２０〜３０重量％用いられる。
なお、データは示さないが、これらの光酸発生剤には、未露光部において、光酸発生剤を混合しない単独の樹脂膜に比べ、未反応の光酸発生剤が混在した樹脂膜は現像液（アミン）に対する溶解速度が著しく遅いという溶解抑制効果がある。
【００１５】
フォトレジスト溶液の製造に適する溶剤は原則としてフォトレジストの不揮発成分、例えば縮合ポリマー及び光酸発生剤及び所望のその他の添加剤が十分に可溶であり、かつこれらの成分と不可逆的に反応しない全ての溶剤である。適する溶媒の実例は、非プロトン性極性溶媒、例えばＮ−メチル−２−ピロリドン、ブチロラクトン、シクロヘキサノン、ジアセトキシエチレングリコール、スルホラン、テトラメチル尿素、Ｎ，Ｎ’−ジメチルアセトアミド、ジメチルホルムアミド、ジメチルスルホキシド、アセトニトリル、ジグラム、フェノール、クレゾール、トルエン等である。
【００１６】
本発明のポジ型フォトレジスト中に存在し得る別の慣用の改良添加剤としては、カップリング剤、均添剤、可塑剤、別の膜形成樹脂、界面活性剤及び安定剤よりなる。これらの改質剤は当業者にとって周知であり、そして関連文献には詳細に記載されている。かかる改質剤の量は全て合わせてもフォトレジスト溶剤の固形分全含有量に基づいて２５重量％を超えることはない。
本発明のフォトレジストはそれ自身公知の方法により成分を溶剤又は溶剤混合物中に混合又は溶解することにより配合される。一旦成分は溶液中に溶解され、得られたフォトレジスト溶液は０．１〜１μｍの細孔を有するろ過膜を用いてろ過される。
主用な用途分野はミクロ電子工学及びオプトエレクトロニクス回路ならびに部品の製造である。この利用のためにこれら材料は一時の間に合わせのフォトレジストマスク並びに永久構造体として例えば絶縁層、保護膜もしくは不導体層、誘電層又は液晶表示要素における配向膜として働く。
【００１７】
基板上への被覆は通常、浸漬、噴霧、ロール塗り又はスピンコーティングによって行われる。生じた層の厚さはフォトレジスト溶液の粘度、固形分含量及びスピンコーティング速度に依存する。本発明のフォトレジストは０．１〜５００μｍ、好ましくは１〜１００μｍの層厚を持つ層及びレリーフ構造を作ることができる。多層回路における薄層は一時の間に合わせのフォトレジストとして又は絶縁層として１〜５０μｍにすることができる。
フォトレジストを基材に塗布した後、これに普通５０〜１２０℃の温度範囲で予備乾燥させる。オーブン又は加熱プレートを使用できる。オーブン中での乾燥時間は５〜６０分である。
【００１８】
その後、フォトレジスト層は輻射を受ける。通常、化学線の光が使用されるが、また高エネルギー放射線、例えばＸ線又は電子ビーム線を試用することができる。直接照射又は露光マスクを介して行うことができる。また、輻射線ビームをフォトレジスト層の表面に当てることもできる。
普通、輻射は２５０〜４５０ｎｍ、好ましくは３００〜４００ｎｍの中心波長を発する紫外線ランプを用いて行われる。市販で入手できる輻射装置、例えば接触又は非接触露光機、走査投光型露光装置又はウエハステッパーを使用することが好ましい。
露光の後、ついでパターンはフォトレジストの照射域を取り除くアルカリ性現像液で層を処理する。例えば、浸漬又は噴霧により基材の露光部を現像する。
【００１９】
現像液は上記のアミンを含む、水若しくは有機溶剤、又は水と有機溶剤との混合物が用いるのがよい。
有機溶剤は用いた縮合系化合物を溶解し、光酸発生剤や各種添加物を溶解する性能を持つ溶媒が用いられる。好ましい例としてジメチルホルムアミド、Ｎ−メチル−２−ピロリドン、ジメチルスルホキシド、テトラメチル尿素、ブチロラクトン、ジアセトキシエチレングリコール、シクロヘキサノン等が用いられる。
光酸発生剤の存在下での縮合型ポリマーの化学放射線の照射による分子量の変化はない。むしろ、その後の現像液中への浸漬によって光照射部分が分解し、アルカリ性溶液に溶解して現像が認められる。標題に示す反応現像である。
従来の酸付加によるアルカリ性溶液への溶解性の増大という溶解性の変化に基づく現像法と著しく異なる。
現像は露光エネルギー、現像剤のアルカリ性の強さ、現像の形式、予備乾燥温度、現像温度、現像時間を調節して行う。
現像停止は、普通、非溶剤、例えばイソプロパノール、脱イオン水、微酸性水溶液中への浸漬又は噴霧によって行われる。
本発明のポジ型フォトレジストは０．１〜５００μｍ、好ましくは１〜１００μｍの層厚を有するポリマー被膜及び鋭い輪郭丸みを付けられたれレリーフ構造をとることができる。
ポストベークは材料の種類によって異なるが、１５０〜３５０℃の範囲で行うことができる。
【００２０】
【実施例】
以下、実施例にて本発明を例証するが、本発明を限定することを意図するものではない。
本実施例においては、以下の方法でフォトレジストを形成させて観察した。
フォトレジストは、各実施例のフォトレジスト配合物を３ミクロン細孔径の濾過膜で濾過して製造した。このフォトレジスト配合物を、表面処理した直径１０ｃｍの銅箔（三井金属株式会社製品、３５ミクロン厚さ）の表面上に、スピンコート法で塗布した。ついで、赤外線熱風乾燥機中で９０℃１０分間乾燥した。このフォトレジスト膜の厚さは、約１５μｍである。このフォトレジスト配合塗布膜上に、ポジ型フォトマスク用のテストパターン（１０、１５、２０、２５、――、２００μｍのスルーホール及びラインアンドベースパターン）を置き、２ｋｗ超高圧水銀灯照射装置（オーク製作所製品：ＪＰ−２０００Ｇ）を用いて、画像が得られる露光量で照射した（紫外線照射 ２０００ｍＪ／ｃｍ^２）。現像液中に、上記照射後の塗布膜を上記時間浸漬した後、脱イオン水で水洗し、赤外線ランプで乾燥後、解像度を観察した。いくつかの実施例においては、形成したフォトレジストをＳＥＭ（日本電子製、走査型電子顕微鏡JSM-5500LV、加速電圧：１０ｋＶ）により撮影した。
【００２１】
実施例１
２００ｍLナスフラスコにペレット状のビスフェノールＡ型ポリカーボネート(以下、ＰＣという。)２０ｇ、ＮＭＰ６０ｇを添加して、１８０℃で機械的に撹拌して加熱溶解させ、ＰＣのＮＭＰワニスを得た(固形分含量: ２５重量％)。次いで、ジアゾナフトキノン系感光剤ＰＣ−５(東洋合成製、１，２−ナフトキノン−２−ジアジド−５−スルホン酸−ｐ−クレゾールエステル)１．５ｇをＮＭＰ５ｇに溶解させた溶液にこのワニス２０ｇを添加して、室温で約１時間、スターラーで撹拌してフォトレジスト配合物（感光性ＰＣ組成物）を調製した。
この溶液を３５μｍの電解銅箔上(シャイン面もしくはマット面)にスピンコート法(６００ｒｐｍ／１０秒＋１０００ｒｐｍ／３０秒)で塗布し、遠赤外線熱風循環式乾燥機でプリベーク後(９０℃／１０分)、膜厚１５μｍの感光性ＰＣ被塗膜を得た。紫外線露光機(オーク社製)を用い、ＰＥＴ製のフォトマスクを介してｉ線からｇ線帯域の光を照射した。ｉ線帯域用の照度計で測定した露光量は１０００ｍＪ／ｃｍ^２である。露光後、エタノールアミン１００ｇ、ＮＭＰ１００ｇ、イオン交換水１００ｇからなる現像液を用いて、超音波処理下もしくは浸漬法により、４５℃で３分間現像を行い、イオン交換水１００ｇで１分間リンスしてポジ型の像を得た。解像度はラインアンドスペースパターンで１０μｍであった。このフォトレジストのＳＥＭ写真を図１に示す。
【００２２】
実施例２
ＰＣの代わりに、ポリアリレート(ユニチカ製 Ｕポリマー、以下「ＰＡｒ」という。)を用いて、実施例１と同様の操作を行い、フォトレジスト配合物を調製した。
このフォトレジスト配合物を用いて、実施例１と同様の操作を行い、膜厚１５μｍの感光性被塗膜を得た。次に現像液としてエタノールアミン４００ｇ、ＮＭＰ１００ｇ、イオン交換水１００ｇからなる現像液を用い、４５℃で１２分現像を行い、その他は実施例１と同様の操作を行い、ポジ型の像を得た。解像度はラインアンドスペースパターンで１０μｍであった。このフォトレジストのＳＥＭ写真を図２に示す。
【００２３】
実施例３
実施例１と同様の操作を行い、フォトレジスト配合物（ＰＣ）を調製した。
このフォトレジスト配合物を用いて、実施例１と同様の操作を行い、膜厚１４μｍの感光性被塗膜を得た。露光量を２０００ｍＪ／ｃｍ^２として、現像液としてヒドロキシルアミン１００ｇ、ＮＭＰ１００ｇ、イオン交換水１００ｇからなる現像液を用い、４１℃で７分現像を行い、その他は実施例１と同様の操作を行なって、ポジ型の像を得た。解像度はラインアンドスペースパターンで２０μｍであった。
【００２４】
実施例４
実施例１と同様の操作を行い、フォトレジスト配合物（ＰＣ）を調製した。
このフォトレジスト配合物を用いて、実施例１と同様の操作を行い、膜厚１４μｍの感光性被塗膜を得た。露光量を２０００ｍＪ／ｃｍ^２として、現像液としてヒドラジン−水和物１００ｇ、ＮＭＰ１００ｇ、イオン交換水１００ｇからなる現像液を用い、４１℃で２分現像を行い、その他は実施例１と同様の操作を行なって、ポジ型の像を得た。解像度はラインアンドスペースパターンで２０μｍであった。
【００２５】
実施例５
実施例１と同様の操作を行い、フォトレジスト配合物（ＰＣ）を調製した。
このフォトレジスト配合物を用いて、実施例１と同様の操作を行い、膜厚１４μｍの感光性被塗膜を得た。露光量を２０００ｍＪ／ｃｍ^２として、現像液として２５％アンモニア水溶液からなる現像液を用い、４０℃で５分現像を行い、その他は実施例１と同様の操作を行なって、ポジ型の像を得た。解像度はラインアンドスペースパターンで１０μｍであった。このフォトレジストのＳＥＭ写真を図３に示す。
【００２６】
実施例６
ＰＣの代わりに、ポリエーテルイミド（ＧＥ製 Ｕｌｔｅｍ、以下「ＰＥＩ」という。）を用いて、実施例１と同様の操作を行い、フォトレジスト配合物を調製した。
このフォトレジスト配合物を用いて、実施例１と同様の操作を行い、膜厚１５μｍの感光性被塗膜を得た。露光量を２０００ｍＪ／ｃｍ^２として、現像液としてヒドロキシルアミン１００ｇ、ＮＭＰ１００ｇ、イオン交換水１００ｇからなる現像液を用い、４１〜４３℃で２０分現像を行い、その他は実施例１と同様の操作を行なって、ポジ型の像を得た。解像度はラインアンドスペースパターンで２０μｍであった。
【００２７】
実施例７
ＰＣの代わりに、ＰＥＩを用いて、実施例１と同様の操作を行い、フォトレジスト配合物を調製した。
このフォトレジスト配合物を用いて、実施例１と同様の操作を行い、膜厚１５μｍの感光性被塗膜を得た。露光量を２０００ｍＪ／ｃｍ^２として、現像液としてヒドラジン−水和物１００ｇ、ＮＭＰ１００ｇ、イオン交換水１００ｇからなる現像液を用い、４１〜４３℃で２５分現像を行い、その他は実施例１と同様の操作を行なって、ポジ型の像を得た。解像度はラインアンドスペースパターンで１０μｍであった。このフォトレジストのＳＥＭ写真を図４に示す。
【図面の簡単な説明】
【図１】樹脂にＰＣを用い、現像液にエタノールアミンを用いて形成させたフォトレジスト（実施例１）のＳＥＭ写真を示す図である。
【図２】樹脂にＰＡｒを用い、現像液にエタノールアミンを用いて形成させたフォトレジスト（実施例２）のＳＥＭ写真を示す図である。
【図３】樹脂にＰＣを用い、現像液に２５％アンモニア水溶液を用いて形成させたフォトレジスト（実施例５）のＳＥＭ写真を示す図である。
【図４】樹脂にＰＥＩを用い、現像液にヒドラジン−水和物を用いて形成させたフォトレジスト（実施例７）のＳＥＭ写真を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photoresist technique that can be used for manufacturing a semiconductor integrated circuit, a printed wiring board, or a liquid crystal panel, and more specifically, a film is formed using a condensation polymer and a photoacid generator and irradiated with light. The present invention relates to a photoresist technique for forming a positive image using a reactive alkali developer.
[0002]
[Prior art]
Photoresists are commonly used in photolithographic organic polymers used in the related art in photographic deck processing, for the production of printed circuit boards and printed circuit boards, or for the production of semiconductor laminates in microelectronics. .
In order to create circuit structures in the manufacture of microelectronic semiconductor integrated components, the semiconductor substrate is imaged with a photoresist layer coated with a photoresist and subsequent development creates a photoresist relief structure. This relief structure is used on a semiconductor substrate as a mask for creating an actual circuit pattern by etching-doping or coating using a metal or other semiconductor or insulating substrate. Thereafter, the photoresist mask is usually removed. A microchip relief structure is formed on the substrate using a plurality of such processing cycles.
Two different types of photoresists are known: a positive resist and a negative resist. The difference between the two types is that the exposed area of the positive photoresist is removed by the development process, leaving the unexposed area as a layer on the substrate. On the other hand, the irradiation area of the negative working photoresist remains as a relief structure. Positive photoresists have inherently high image resolution and are used in the manufacture of VLSI (very large scale integrated circuits).
[0003]
A normal type of positive photoresist essentially contains at least one novolak resin that is soluble in aqueous alkali in an organic solvent and a photosensitive quinonediazide compound that reduces the solubility of the resin in alkali. Irradiation of a photoresist layer made of such a composition increases the solubility in alkali of the exposed area by photoinduced structural conversion of quinonediazide to a carboxylic acid derivative, which allows development in aqueous alkaline developers. Later, a positive photoresist relief structure is obtained.
In general, a polyimide called kapton is hardly soluble in solvents, so a negative type image was obtained by light irradiation of a system in which an unstable polyamic acid was used as a precursor and an acrylic ester was added to this. .
[0004]
The polymer resist reacts with the chromophore contained by light energy, the polymer structure changes, and its physical properties change. It is classified into one of the changes in the polymer structure caused by light of the polymer incorporating various chromophores: photocrosslinking, photopolymerization, photodecay, and photopolarity change.
Polymers have been found in which the main chain of the polymer is randomly cleaved by light irradiation to lower the molecular weight. Polymers containing carbonyl groups decompose into Type 1 and Type 2 Norrish reactions. Since this series of polymer main chain cleavage occurs through excitation of the main chain carbonyl group, the sensitivity that requires X-rays, electron beams, and short-wavelength ultraviolet rays is low, but it gives very high resolution and excellent profile (M.M. Hatzaki, J. Electrochem. Soc., 116 (7) 1033 (1969); Resist material handbook for semiconductor integrated circuits, supervised by Atsuo Yamaoka, P46, Realize (1996)).
[0005]
[Problems to be solved by the invention]
Conventional photoresists have functional groups capable of reacting with bases (such as carboxyl groups and phenolic hydroxyl groups) on the side chains of polymers, or can react with acids and bases to generate carboxyl groups and phenolic hydroxyl groups. It was essential to have a reactive group (such as an ester or a phenol ether bonded to a protecting group) (for example, JP 2001-66781 A, JP 2001-192573 A, JP 2001-249458 A, etc.). For example, in order to make a simple polycarbonate into a resist by a conventional method, it is necessary to introduce a carboxyl group, a phenolic hydroxyl group or a group in which an appropriate protective group is bonded to the side chain of this polymer. The introduction of these functional groups is very difficult, and the introduction of such a functional group has no other practical meaning.
For these reasons, a general-purpose resin cannot be used in a photoresist based on the conventional concept, and therefore its application is naturally limited.
However, the present invention uses a general resin having a carbonyl group (C═O) bonded to a heteroatom in the main chain without having such a special reactive group in the side chain of the resin skeleton. The object is to provide a means of directly attacking these bonds and destroying them.
[0006]
[Means for Solving the Problems]
In order to solve such problems, the inventors have developed a completely new means called “reactive development image forming method”. This method is a kind of positive type photoresist technology, and first comprises a general-purpose resin containing a carbonyl group (C═O) bonded to a heteroatom, which will be described later, in the main chain and a photoacid generator. After forming with a mixture, this layer is appropriately masked in a desired pattern, and then irradiated with ultraviolet rays. The photoacid generator generates an acid by this ultraviolet irradiation. When this is washed with a developer containing a nucleophilic amine, it reacts with the acid produced by the nucleophilic amine, thereby producing a salt and increasing the polarity of the exposed area. As a result, the nucleophilic amine in the developer attacks the carbonyl group bonded to the hetero atom constituting the main chain of the polymer in the exposed region. This attack breaks the main chain at the carbonyl group. Due to the cleavage of the main chain, the polymer is reduced in molecular weight and dissolved in the developer.
[0007]
In the “reactive development image forming method” of the present invention, a condensed polymer (a polymer containing a carbonyl group bonded to a heteroatom in the main chain) having no special functional group or reactive group in the side chain as described above is photo-photographed. It can be used as a resist material. According to the conventional principle, this type of polymer could not be used as a resist.
[0008]
That is, the present invention relates to a development image forming method comprising irradiating a photoresist layer masked with a desired pattern with ultraviolet rays and then washing the layer with a solvent containing an alkali. A reactive development image forming method comprising a condensed polymer containing a bonded carbonyl group (C = O) in the main chain and a photoacid generator, wherein the alkali is an amine. For the alkali-containing solution, a mixture comprising an amine and at least one of water and an organic solvent is preferable.
The condensation polymer is capable of generating a carboxyl group or a phenolic hydroxyl group by reacting with a functional group capable of reacting with a base (for example, a carboxyl group or a phenolic hydroxyl group), or an acid or a base, particularly on its side chain. It is not necessary to have a reactive group (such as an ester or phenolic ether bonded to a protecting group).
The present invention also relates to a formed product (photoresist formed product) formed by the reaction development image forming method, and further to a semiconductor integrated circuit, a printed wiring board or a liquid crystal panel having the formed product.
[0009]
Here, ultraviolet rays refer to electromagnetic waves having a center at 250 to 450 nm, preferably 300 to 400 nm.
A condensed polymer containing a carbonyl group (C═O) bonded to a heteroatom in the main chain means an imide bond, a carbonate bond, an ester bond, a urethane bond, an amide bond, or these bonds, respectively, in the main chain of the polymer. A polymer containing a plurality.
That is, a condensation polymer containing only a carbonyl group bonded to a hetero atom in the main chain is suitable for the polymer to be the subject of the present invention. Examples thereof include polyetherimide, polyamide, polyamideimide, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyethylene 2,6-naphthalate, polyarylate, polyurethane and the like, and copolymers related thereto.
[0010]
Here, in the reaction development image forming method of the present invention, the stability of such a bond against the nucleophilic attack of the nucleophilic amine is shown in the following table.
[Table 1]

This table shows that the bond on the left is more susceptible to nucleophilic attack (unstable). From this table, the imide bond is relatively unstable and susceptible to amine attack. That is, a nucleophilic substitution reaction can be easily caused without any particular effort on the amine. However, the carbonate, ester, urethane, or amide bond is relatively stable and not susceptible to amine attack. In other words, it is difficult to cause a nucleophilic substitution reaction unless a device for giving strong nucleophilicity to the amine used is used. One of the features of the reaction development image forming method of the present invention is that such a bond having high stability to nucleophilic reaction can be broken. That is, the reaction development image forming method of the present invention is characterized in that a resin having a bond with low reactivity with a nucleophilic reagent such as carbonate, ester, urethane or amide can be used as a target of a photoresist. It can be said.
[0011]
In addition, a polymer to which the reaction development image forming method of the present invention can be preferably applied reacts with a functional group capable of reacting with a base (for example, a carboxyl group or a phenolic hydroxyl group), or an acid or a base, particularly on its side chain. It is not necessary to have a reactive group that can generate a carboxyl group or a phenolic hydroxyl group (such as an ester bonded to a protecting group or a phenol type ether).
[0012]
On the other hand, an amine is a compound having a nitrogen atom having an unshared electron pair, and is classified into an organic amine (including amino acids) and an inorganic amine. These are compounds having nucleophilicity, and react nucleophilically with a carbonyl group bonded to a hetero atom in a polymer in an exposed region having increased polarity by an acid generated by a photoacid generator.
However, even amines considered to be non-nucleophilic may react nucleophilically with carbonyl groups depending on the development conditions, particularly the solvent settings. For example, tetramethylammonium hydroxide (TMAH) is not a preferred amine for the reaction development image forming method of the present invention because it is not nucleophilic under normal conditions, but alcohol / N-methyl-2-pyrrolidone (hereinafter, In a system that does not contain water, such as NMP), or in a solvent system that contains only a small amount of water, the OH anion of TMAH is greatly reduced in the presence of water. It is considered that the reactivity to a carbonyl group is increased in a system such as an organic solvent / NMP that does not contain alcohol.
The basicity of the amine is stronger as the acidity index (pK _a ) is larger, but in the reaction development image forming method of the present invention, the reactivity of the carbonyl group (C═O) to the C atom (nucleophilicity) rather than the basicity. Is important, and is considered to be stronger as the molecular size is smaller. Accordingly, in general, inorganic amines have higher nucleophilicity than organic amines in which large carbon chains are bonded to N atoms, and are suitable for the reaction development image forming method of the present invention. Specific examples of the nucleophilic amine of the present invention are listed in the following table together with acid dissociation constants.
[0013]
[Table 2]

Preferred amines include the hydroxylamine, hydrazine, and ammonia inorganic amines listed in Table 1, and N, N-dimethylethanolamine, N-methylethanolamine, ethanolamine, N-methylmorpholine, methylamine, ethylamine, Examples include n-propylamine, n-butylamine, benzylamine, cyclohexylamine, ethylenediamine, and morpholine, and organic amines such as amino acids such as glycine and β-alanine.
Inorganic amines have the advantage that they do not require explosion-proof equipment and have less environmental impact than organic amines.
In the method of the present invention, it is most preferable to use a polymer having an imide bond, which is a bond that is most susceptible to nucleophilic attack by a nucleophilic amine (low stability), and an inorganic amine having strong nucleophilicity. I can say that.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The photoacid generator present in the positive photoresist of the present invention is a compound that generates acid upon irradiation with actinic radiation, and quinonediazide compounds, onium salts, sulfonate esters, organic halogen compounds, and the like are used. In particular, the quinonediazide compound is 1,2-naphthoquinone-2-diazide-5-sulfonic acid or 1,2-naphthoquinone-2-diazide-4-sulfonic acid and a low molecular weight aromatic hydroquinone compound such as 2,3,4-trihydroxy. Ester-forming compounds of benzophenone, 2,3,4,4′-tetrahydroxybenzophenone and trihydroxybenzene, such as 1,3,5-trihydroxybenzene, or cresol. Examples of onium salts include triphenylsulfonium hexafluoroantimonate and triphenylsulfonium hexafluorophosphate. These are used with esters such as t-butyl benzoate. Among these, 1,2-naphthoquinone-2-diazide-5-sulfonic acid-p-cresol ester is particularly preferable. The photoacid generator is used in the photoresist in an amount of 5 to 50% by weight, preferably 10 to 40% by weight, more preferably 20 to 30% by weight based on the total solid content.
Although not shown in the data, these photoacid generators developed a resin film containing unreacted photoacid generators in the unexposed area compared to a single resin film not mixed with the photoacid generator. There is a dissolution inhibiting effect that the dissolution rate in the liquid (amine) is extremely slow.
[0015]
Solvents suitable for the production of photoresist solutions are in principle sufficiently soluble in the non-volatile components of the photoresist, such as condensation polymers and photoacid generators and other desired additives, and do not irreversibly react with these components. All solvents. Examples of suitable solvents are aprotic polar solvents such as N-methyl-2-pyrrolidone, butyrolactone, cyclohexanone, diacetoxyethylene glycol, sulfolane, tetramethylurea, N, N′-dimethylacetamide, dimethylformamide, dimethyl sulfoxide, Acetonitrile, digram, phenol, cresol, toluene and the like.
[0016]
Other conventional improving additives that may be present in the positive photoresists of the present invention include coupling agents, leveling agents, plasticizers, other film-forming resins, surfactants and stabilizers. These modifiers are well known to those skilled in the art and are described in detail in the relevant literature. Even when all of these modifiers are combined, they do not exceed 25% by weight based on the total solid content of the photoresist solvent.
The photoresist of the present invention is formulated by mixing or dissolving the components in a solvent or solvent mixture by a method known per se. Once the components are dissolved in the solution, the resulting photoresist solution is filtered using a filtration membrane having 0.1-1 μm pores.
The main application areas are the manufacture of microelectronics and optoelectronic circuits and components. For this purpose, these materials act as a temporary photoresist mask as well as a permanent structure, for example as an insulating layer, a protective or non-conductive layer, a dielectric layer or an alignment film in a liquid crystal display element.
[0017]
Coating onto the substrate is usually done by dipping, spraying, roll coating or spin coating. The resulting layer thickness depends on the viscosity, solids content and spin coating speed of the photoresist solution. The photoresist of the present invention can make a layer and a relief structure having a layer thickness of 0.1 to 500 μm, preferably 1 to 100 μm. The thin layer in the multi-layer circuit can be 1-50 μm as a temporary photoresist or as an insulating layer.
After the photoresist is applied to the substrate, it is usually pre-dried at a temperature range of 50 to 120 ° C. An oven or a heating plate can be used. The drying time in the oven is 5 to 60 minutes.
[0018]
Thereafter, the photoresist layer receives radiation. Usually actinic light is used, but high-energy radiation such as X-rays or electron beam rays can also be tried. Direct irradiation or via an exposure mask can be performed. A radiation beam can also be applied to the surface of the photoresist layer.
Usually, the radiation is carried out using an ultraviolet lamp emitting a central wavelength of 250 to 450 nm, preferably 300 to 400 nm. It is preferable to use a commercially available radiation apparatus such as a contact or non-contact exposure machine, a scanning projection type exposure apparatus or a wafer stepper.
After exposure, the pattern is then treated with an alkaline developer that removes the exposed areas of the photoresist. For example, the exposed portion of the substrate is developed by dipping or spraying.
[0019]
The developer is preferably water or an organic solvent containing the above amine, or a mixture of water and an organic solvent.
As the organic solvent, a solvent having the performance of dissolving the condensed compound used and dissolving the photoacid generator and various additives is used. Preferred examples include dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, tetramethylurea, butyrolactone, diacetoxyethylene glycol, cyclohexanone and the like.
There is no change in the molecular weight of the condensed polymer in the presence of the photoacid generator due to irradiation with actinic radiation. Rather, the light-irradiated portion is decomposed by subsequent immersion in a developing solution and dissolved in an alkaline solution to allow development. Reaction development shown in the title.
This is significantly different from the conventional development method based on a change in solubility, ie, an increase in solubility in an alkaline solution by acid addition.
Development is performed by adjusting the exposure energy, the alkalinity of the developer, the type of development, the preliminary drying temperature, the development temperature, and the development time.
Development termination is usually accomplished by immersion or spraying in a non-solvent such as isopropanol, deionized water, a slightly acidic aqueous solution.
The positive photoresist of the present invention can have a polymer film having a layer thickness of 0.1 to 500 μm, preferably 1 to 100 μm, and a sharp contoured relief structure.
The post-baking can be performed in the range of 150 to 350 ° C., depending on the type of material.
[0020]
【Example】
The following examples illustrate the invention, but are not intended to limit the invention.
In this example, a photoresist was formed by the following method and observed.
The photoresist was prepared by filtering the photoresist formulation of each example through a 3 micron pore size filter membrane. This photoresist composition was applied by spin coating on the surface of a surface-treated copper foil having a diameter of 10 cm (product of Mitsui Kinzoku Co., Ltd., 35 micron thickness). Subsequently, it dried at 90 degreeC for 10 minute (s) in the infrared hot air dryer. The thickness of this photoresist film is about 15 μm. A test pattern (10, 15, 20, 25, ..., 200 μm through-hole and line-and-base pattern) for a positive photomask is placed on this photoresist-blended coating film, and a 2 kW ultra-high pressure mercury lamp irradiation device (Oak) Using a mill product: JP-2000G), irradiation was performed with an exposure amount at which an image was obtained (ultraviolet irradiation 2000 mJ / cm ² ). The coating film after the irradiation was immersed in the developer for the above time, washed with deionized water, dried with an infrared lamp, and the resolution was observed. In some examples, the formed photoresist was photographed by SEM (manufactured by JEOL Ltd., scanning electron microscope JSM-5500LV, acceleration voltage: 10 kV).
[0021]
Example 1
20 g of pelleted bisphenol A polycarbonate (hereinafter referred to as PC) and 60 g of NMP were added to a 200 mL eggplant flask, and mechanically stirred at 180 ° C. to dissolve with heating to obtain an NMP varnish of PC (solid content) : 25% by weight). Next, 20 g of this varnish was added to a solution of 1.5 g of diazonaphthoquinone photosensitizer PC-5 (Toyo Gosei Co., Ltd., 1,2-naphthoquinone-2-diazide-5-sulfonic acid-p-cresol ester) dissolved in 5 g of NMP. The resultant was added and stirred with a stirrer at room temperature for about 1 hour to prepare a photoresist composition (photosensitive PC composition).
This solution was applied onto 35 μm electrolytic copper foil (shine surface or matte surface) by spin coating (600 rpm / 10 seconds + 1000 rpm / 30 seconds), and prebaked with a far-infrared hot air circulation dryer (90 ° C./10 minutes). ), A photosensitive PC coated film having a film thickness of 15 μm was obtained. Using an ultraviolet exposure machine (manufactured by Oak Co., Ltd.), light in the i-line to g-line band was irradiated through a PET photomask. The exposure amount measured with an illuminometer for the i-line band is 1000 mJ / cm ² . After exposure, using a developer composed of 100 g of ethanolamine, 100 g of NMP, and 100 g of ion-exchanged water, development is performed at 45 ° C. for 3 minutes under ultrasonic treatment or by an immersion method. A mold image was obtained. The resolution was 10 μm with a line and space pattern. An SEM photograph of this photoresist is shown in FIG.
[0022]
Example 2
A photoresist formulation was prepared in the same manner as in Example 1 except that polyarylate (U polymer manufactured by Unitika, hereinafter referred to as “PAr”) was used instead of PC.
Using this photoresist composition, the same operation as in Example 1 was performed to obtain a photosensitive coating film having a thickness of 15 μm. Next, a developer composed of 400 g of ethanolamine, 100 g of NMP, and 100 g of ion-exchanged water was used as a developer, and development was performed at 45 ° C. for 12 minutes. Other operations were the same as in Example 1, and a positive image was obtained. . The resolution was 10 μm with a line and space pattern. An SEM photograph of this photoresist is shown in FIG.
[0023]
Example 3
The same operation as in Example 1 was performed to prepare a photoresist composition (PC).
Using this photoresist composition, the same operation as in Example 1 was performed to obtain a photosensitive coating film having a thickness of 14 μm. The exposure amount was 2000 mJ / cm ² , and a developer composed of 100 g of hydroxylamine, 100 g of NMP, and 100 g of ion-exchanged water was used as the developer, and development was performed at 41 ° C. for 7 minutes. A positive image was obtained. The resolution was 20 μm with a line and space pattern.
[0024]
Example 4
The same operation as in Example 1 was performed to prepare a photoresist composition (PC).
Using this photoresist composition, the same operation as in Example 1 was performed to obtain a photosensitive coating film having a thickness of 14 μm. The exposure was 2000 mJ / cm ² , and a developer consisting of 100 g of hydrazine-hydrate, 100 g of NMP, and 100 g of ion-exchanged water was used as the developer, and development was performed at 41 ° C. for 2 minutes. To obtain a positive image. The resolution was 20 μm with a line and space pattern.
[0025]
Example 5
The same operation as in Example 1 was performed to prepare a photoresist composition (PC).
Using this photoresist composition, the same operation as in Example 1 was performed to obtain a photosensitive coating film having a thickness of 14 μm. The exposure amount was 2000 mJ / cm ² , and a developer composed of a 25% aqueous ammonia solution was used as the developer, and development was performed at 40 ° C. for 5 minutes. Otherwise, the same operations as in Example 1 were performed to obtain a positive image. Obtained. The resolution was 10 μm with a line and space pattern. An SEM photograph of this photoresist is shown in FIG.
[0026]
Example 6
A photoresist formulation was prepared in the same manner as in Example 1 using polyetherimide (GE, ULTEM, hereinafter referred to as “PEI”) instead of PC.
Using this photoresist composition, the same operation as in Example 1 was performed to obtain a photosensitive coating film having a thickness of 15 μm. The exposure amount was 2000 mJ / cm ² , and a developer composed of 100 g of hydroxylamine, 100 g of NMP, and 100 g of ion-exchanged water was used as the developer, and development was performed at 41 to 43 ° C. for 20 minutes. A positive image was obtained. The resolution was 20 μm with a line and space pattern.
[0027]
Example 7
A photoresist formulation was prepared using PEI instead of PC in the same manner as in Example 1.
Using this photoresist composition, the same operation as in Example 1 was performed to obtain a photosensitive coated film having a thickness of 15 μm. The exposure amount was 2000 mJ / cm ² , and a developer composed of 100 g of hydrazine hydrate, 100 g of NMP, and 100 g of ion-exchanged water was used as the developer, and development was performed at 41 to 43 ° C. for 25 minutes. As a result, a positive image was obtained. The resolution was 10 μm with a line and space pattern. An SEM photograph of this photoresist is shown in FIG.
[Brief description of the drawings]
FIG. 1 is an SEM photograph of a photoresist (Example 1) formed using PC as a resin and ethanolamine as a developer.
FIG. 2 is a SEM photograph of a photoresist (Example 2) formed using PAr as a resin and ethanolamine as a developer.
FIG. 3 is a view showing an SEM photograph of a photoresist (Example 5) formed using PC as a resin and 25% aqueous ammonia as a developer.
FIG. 4 is a view showing an SEM photograph of a photoresist (Example 7) formed using PEI as a resin and hydrazine-hydrate as a developer.

Claims (8)

In a development imaging process comprising irradiating a photoresist layer masked with a desired pattern with ultraviolet light and then washing the layer with a solvent containing a nucleophilic amine , the carbonyl bonded to the heteroatom. A reactive development image forming method comprising a condensation type polymer (excluding an alicyclic polymer) containing a group (C = O) in the main chain and a photoacid generator. 2. The reaction development image forming method according to claim 1, wherein the photoacid generator is an onium salt used in combination with a quinonediazide compound or an organic acid ester. The reactive development image forming method according to claim 1, wherein the condensation type polymer has a bond of carbonate, ester, urethane, or amide, and does not have an imide bond. The condensed polymer does not have a functional group capable of reacting with a base, or a reactive group capable of generating a carboxyl group or a phenolic hydroxyl group by reacting with an acid or base, particularly in its side chain. The reaction development image forming method according to any one of claims 1 to 3 . The reaction development image forming method according to any one of claims 1 to 4 , wherein the solution containing the nucleophilic amine is a mixture comprising a nucleophilic amine and at least one of water and an organic solvent. . The reactive development image forming method according to any one of claims 1 to 5, wherein the wavelength of ultraviolet rays to be irradiated is 250 to 450 nm. A formed product formed by the reactive development image forming method according to any one of claims 1 to 6 . A semiconductor integrated circuit, a printed wiring board, or a liquid crystal panel having the formed product according to claim 7 .

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