JP4170077B2

JP4170077B2 - Unnecessary film removing apparatus, unnecessary film removing method, and mask blank manufacturing method

Info

Publication number: JP4170077B2
Application number: JP2002339377A
Authority: JP
Inventors: 英雄小林; 敬司浅川
Original assignee: Hoya Corp
Current assignee: Hoya Corp
Priority date: 2002-11-22
Filing date: 2002-11-22
Publication date: 2008-10-22
Anticipated expiration: 2022-11-22
Also published as: JP2004172544A

Description

【０００１】
【発明の属する技術分野】
本発明は、例えば、マスクブランクス、半導体基板、磁気ディスク基板およびカラーフィルター等の基板表面の一部に形成された不要膜を除去する不要膜除去装置および不要膜除去方法、並びにそれを用いるマスクブランクスの製造方法に関する。
【０００２】
【従来の技術】
半導体基板、フォトマスクおよびフォトマスクブランクス、磁気ディスク基板、カラーフィルター等を製造する分野においては、基板の一主表面に形成された塗布膜その他の膜における不要な一部を除去することがしばしば要求される。
基板上にレジスト膜、レジスト下地反射防止膜（BARC:Bottom Anti-Reflective Coating）、レジスト上層反射防止膜（TARL:Top Anti-Reflective Layer）、レジスト上層保護膜、導電性膜等（本明細書中、代表（総称）してレジストと称す）を回転塗布法等で形成する場合、あるいはそれらを積層形成する場合、塗布液が基板表面の周縁部に溜まり、あるいは、基板側面、場合によっては基板裏面にまで回りこみ、フォトマスクブランクスの周縁部に比較的厚膜なレジスト膜が形成される。
【０００３】
この基板周縁部のレジスト膜は、例えば、フォトマスクブランクスを容器に出し入れする際に容器との接触によって剥離・脱落し易い。また、この厚膜な部位は、後のマスク製造工程で現像液等の薬液処理がなされた際にクラックが入り剥離・脱落し易く、塵埃となってフォトマスクブランクス自身あるいは各種処理装置に再付着し、最終的にフォトマスクブランクスを原材料とする製品であるマスク（レチクルを含む）の欠陥の原因あるいは製造歩留まりの低下の原因となる。
また、レジスト膜が基板主表面に形成されたフォトマスクブランクスを露光装置に取り付ける時に、基板周縁部を支持する構造となっている場合があるが、この場合には、基板周縁部が盛上っていると良好に支持されないことになる。
更に、上記露光装置が電子線マスク描画装置である場合、露光時にフォトマスクブランクスの接地を取る際、レジスト膜の下のクロムを主成分とする遮光膜（導電性膜）と接地プローブとが良好に接触しないという問題が生じる。
従って、このような場合には基板周縁部の不要な塗布膜を除去する必要がある。
【０００４】
上記の問題点を解決するため、基板周縁部に形成される不要なレジスト膜を除去する技術として、特開２００１−２５９５０２号公報に開示されている方法がある。この不要な膜を除去する方法は、レジスト膜を塗布形成後、周縁部（除去する不要膜の上方に位置する部位）に微細な孔が多数形成されたカバー部材である遮蔽部材を基板上に載置し、遮蔽部材上方より溶剤を供給することにより、溶剤が微細な孔を介して基板周縁部に供給され、基板周縁部に形成されたレジスト膜を溶解除去していた。また、基板と遮蔽部材との間隔は、基板中心側の非除去領域に溶剤が流れ込まないように、溶剤の表面張力が働く一定間隔になるように、各辺同じ位置に前記孔に糸（間隔調整部材）が通されている。また、基板は、基板四隅に各２箇所ずつ基板側面と一定のクリアランスを持って配置された基板保持部材を備えた基板保持台座に単に載置されるだけのものであった。
【０００５】
近年、基板の有効領域の拡大化により、除去領域幅の厳密な制御が必要とされている。従来の不要膜除去装置は、上述の構成を取っているため、基板と基板保持手段とのガタツキや偏芯、基板と遮蔽部材とのガタツキや偏芯によって、基板保持台座に対する基板の位置精度（重ね合わせ精度）や、基板に対する遮蔽部材の位置精度（重ね合わせ精度）が悪く、不要膜除去後のレジスト膜端部の形状精度（不要膜除去幅の均一性）が悪く、以下のような問題点が顕著になった。
１）基板周縁部における不要膜除去後のレジスト膜端部の形状精度が悪いため、マスク作製後の外観を損ねていた。
２）基板周縁部における不要膜除去後のレジスト膜端部の形状精度が悪いため、基板周縁部の不要膜が除去されたフォトマスクブランクスを使ってフォトマスクを作製したときの周縁部に位置する補助パターン（アライメントマークや品質保証パターン）のパターン不良（欠損や形状不良等）の原因となっていた。
３）また、不要膜を除去する前の回転塗布方法による（レジスト）成膜工程においても、回転塗布装置における被処理基板を支持する回転保持手段が、単に被処理基板を載置するだけの構造でしかなく、被処理基板の中心と、回転保持手段の回転中心がずれた（偏芯した）状態でレジスト膜を回転塗布することがあり、不要膜除去前の基板周縁部における比較的厚膜な部位の幅あるいは膜厚が偏ることにより、基板周縁部の不要膜除去が完全に行われず、不要膜の残滓が発生することがあった。
【０００６】
【特許文献１】
特開２００１−２５９５０２号公報
【０００７】
【発明が解決しようとする課題】
そこで、本発明は、前述のような従来技術の問題点を解決するため、
第１に基板と基板保持手段との偏芯やガタツキ、更には基板と遮蔽部材の偏芯やガタツキを抑制して、不要膜除去後のレジスト膜端部の形状精度（不要膜除去幅の均一性）が良好になり、且つ、不要膜除去後の不要膜残滓の発生を抑制する不要膜除去装置および不要膜除去方法、並びにこれを用いるフォトマスクブランクスの製造方法を提供することを第１の課題とする。
第２に、基板と基板保持手段との偏芯やガタツキ、更には基板と遮蔽部材の偏芯やガタツキを抑制して、不要膜除去後のレジスト端部の形状精度（不要膜除去幅の均一性）を良好にし、且つ、回転塗布方法による塗布膜の成膜工程において基板周縁部における比較的厚膜な部位の幅或いは膜厚の偏りを抑えて、不要膜除去後の不要膜残滓の発生を防止する不要膜除去方法、並びにそれを用いるフォトマスクブランクスの製造方法を提供することを第２の課題とする。
【０００８】
尚、本発明でいうマスクブランクスには、透過型マスクブランク、反射型マスクブランクの何れも指し、それらの構造は、基板上に被転写体に転写すべく転写パターンとなる薄膜と、レジスト膜とを有する。
透過型マスクブランクは、基板として透光性基板を使用し、転写パターンとなる薄膜は、被転写体に転写するときに使用する露光光に対し光学的変化をもたらす薄膜（例えば、遮光機能を有する薄膜）が使用されたフォトマスクブランクである。ここで、露光光に対し光学的変化をもたらす薄膜とは、露光光を遮断する遮光膜や、露光光の位相差を変化させる位相シフトマスクなどを指す。
従って、本発明で言うフォトマスクブランクは、遮光機能を有する薄膜として遮光膜が形成された通常のフォトマスクブランクと、遮光機能を有する薄膜としてハーフトーン膜が形成された位相シフトマスクブランク（ハーフトーン型位相シフトマスクブランク）、位相シフト膜が形成された位相シフトマスクブランクなどを含む。
【０００９】
尚、遮光機能を有する薄膜として、上記のハーフトーン膜と遮光膜を積層させたものであっても構わない。また、遮光機能を有する薄膜のほかに位相シフト機能を持たせた層が形成された位相シフトマスクブランクを含むものとする。位相シフト機能を持たせた層は、位相シフト機能を透光性基板を掘り込むことにより形成する場合は、透光性基板が位相シフト機能をもつ層となる。また、位相シフト層を形成しても良い。
また、反射型マスクブランクは、基板として低熱膨張基板を使用し、その基板上に光反射多層膜、転写パターンとなる光吸収体膜とを有するマスクブランクである。
また、マスクブランクには、上述の膜以外に、レジスト下地反射防止膜（ＢＡＲＣ：ＢｏｔｔｏｍＡｎｔｉ−ＲｅｆｌｅｃｔｉｖｅＣｏａｔｉｎｇ）、レジスト上層反射防止膜（ＴＡＲＬ：ＴｏｐＡｎｔｉ−ＲｅｆｌｅｃｔｉｖｅＬａｙｅｒ）、レジスト上層保護膜、導電性膜等の膜が形成されても良い。
【００１０】
【課題を解決するための手段】
本発明は、上述の課題を解決するために、基板、更には遮蔽部材の中心が、基板保持手段の回転中心と一致するように機械的に押付けて固定する基板用可動固定手段、更には遮蔽部材用可動固定手段を備えることによって、基板と基板保持手段との偏芯およびガタツキや、更には基板と遮蔽部材との偏芯およびガタツキ、即ちそれぞれの重ね合わせ精度の悪化を抑制して、不要膜除去後の除去端部（例えば、レジスト膜端部）の形状精度（不要膜除去幅の均一性）を向上させ、更には不要膜除去後の不要膜残滓の発生を抑制することができる不要膜除去装置および不要膜除去方法、並びにそれを用いるマスクブランクスの製造方法を提供するものである。
また、不要膜を除去する前の膜形成工程は、回転塗布装置による回転塗布工程を含むものであって、前記回転塗布装置は、基板を回転可能に保持する回転保持手段に、基板の中心が前記回転保持手段の回転中心と一致するように、前記基板を機械的に押付けて固定する基板固定手段を備えており、回転塗布工程中、被処理基板の中心と回転保持手段の中心が一致するようにしたことにより、不要膜除去前における基板周縁部の比較的厚膜な部位の幅あるいは膜厚の偏りを抑えて、不要膜除去後の除去部分の形状精度を向上させ、かつ、不要膜除去後の不要膜残滓の発生を防止する不要膜除去方法、およびマスクブランクスの製造方法を提供するものである。即ち、その要旨とするところは、特許請求の範囲に記載した通りの下記内容である。
【００１１】
（１）マスクブランクス表面に形成された膜のうち周縁部を含む不要な部分のみに薬液を供給して、前記マスクブランクスに形成された不要な膜部分を除去する不要膜除去装置であって、該不要膜除去装置は、前記マスクブランクスを面内回転するように保持する基板保持手段と、前記薬液を供給する薬液供給手段と、前記マスクブランクス主表面の除去領域において、前記マスクブランクス主表面と一定の間隙を形成し、且つ前記マスクブランクス主表面の非除去領域において、前記間隙よりも大きい空間が形成されるように前記マスクブランクス主表面を覆う遮蔽部材とを有するものであって、前記基板保持手段は、前記マスクブランクスの中心が前記基板保持手段の回転中心と一致するように、前記マスクブランクスを機械的に押付けて固定する基板用可動保持手段を備え、前記遮蔽部材は、前記基板保持手段の回転中心と前記遮蔽部材の回転中心とが一致するように位置決めされて前記基板保持手段に固定されており、前記基板用可動保持手段により前記マスクブランクスを機械的に押し付けて前記基板保持手段に固定した状態で前記基板保持手段を回転させながら、前記薬液供給手段により前記間隙中に薬液を供給することで、前記マスクブランクス主表面の除去領域における不要な膜を除去することを特徴とする不要膜除去装置。
（２）前記基板保持手段は、前記遮蔽部材の中心が前記基板保持手段の回転中心と一致するように、前記遮蔽部材を機械的に押付けて固定する遮蔽部材用可動保持手段を備えていることを特徴とする（１）に記載の不要膜除去装置。
この解決手段によれば、基板および遮蔽部材の中心が、基板保持手段の回転中心と一致するように基板および遮蔽部材が固定されて保持されるので、回転時における基板および遮蔽部材の偏芯およびガタツキが低減でき、その結果、不要膜除去幅の均一性をより一層向上させ、不要膜除去後の不要膜残滓の発生を抑制することができる。
【００１２】
（３）前記間隙は、前記薬液が間隙中をつたわって間隙中に流れ込み、かつ、間隙中にのみ保持されることが可能な大きさに設定されていることを特徴とする（１）または（２）に記載の不要膜除去装置。
本発明の不要膜除去装置は、前記間隙を、薬液が間隙中を伝わって間隙中に流れ込み、かつ、間隙中にのみ保持されることが可能な大きさに設定されている。従って、薬液は基板主表面の除去領域において、基板と遮蔽部材との間に形成された間隙において、薬液の表面張力によるメニスカスが働き、間隙中に薬液は満た（供給）されるが、基板主表面の非除去領域に形成された空間には侵入しない。
また、遮蔽部材は、基板の主表面に形成された不要な膜の領域（除去領域）において、基板主表面から一定の間隙を設け、かつ一定の幅を持って設け、該間隔並びに幅を調整することによって、基板主表面における除去領域（幅）を厳密に制御することができる。
【００１３】
（４）（１）乃至（３）の何れか１項に記載の不要膜除去装置を用いた不要膜除去方法であって、前記基板保持手段に前記マスクブランクスを載置し、少なくとも前記基板用可動保持手段によって前記マスクブランクスの中心が前記基板保持手段の回転中心と一致するように前記マスクブランクスおよび前記遮蔽部材をともに回転させながら、前記薬液供給手段により薬液を供給し、前記マスクブランクス表面に形成された膜のうち周縁部を含む不要な部分に薬液を供給することにより不要な膜部分を除去することを特徴とする不要膜除去方法。
この解決手段によれば、基板の中心が基板保持手段の回転中心と一致するように、更には、遮蔽部材の中心が基板保持手段の回転中心と一致するように、それぞれ基板用可動保持手段、遮蔽部材用可動保持手段によって機械的に押し付けて、基板、遮蔽部材が基板保持手段に固定されて保持されるので、回転時の基板と基板保持手段の偏芯やガタツキ、更には基板と遮蔽部材の偏芯やガタツキが抑制でき、その結果、不要膜除去幅の均一性を向上させ、不要膜除去後の不要膜残滓の発生を抑制することができる。
（５）前記マスクブランクス表面に形成された膜は、回転塗布装置による回転塗布工程によって成膜された塗布膜を含み、前記回転塗布装置は、前記マスクブランクスを回転可能に保持する回転保持手段に、前記マスクブランクスの中心が前記回転保持手段の回転中心と一致するように、前記マスクブランクスを機械的に押付けて固定する基板用可動保持手段を備えており、回転塗布工程中、前記マスクブランクスの中心と回転保持手段の中心が一致するようにしたことを特徴とする（４）に記載の不要膜除去方法。
この解決手段によれば、不要膜除去前の基板周縁部に形成される比較的厚膜な部位の幅或いは膜厚の偏りを抑えることができるので、不要膜残滓を防止することができるとともに、不要膜除去幅の均一性を向上させることができる。
【００１４】
（６）基板上に、被転写体に転写すべく転写パターンとなる薄膜とレジスト膜とを形成する膜形成工程を有するマスクブランクスの製造方法において、前記膜形成工程において不要な部分に形成された不要膜を（４）または（５）に記載の不要膜除去方法で除去する不要膜除去工程を有することを特徴とするマスクブランクスの製造方法。
この解決手段によれば、不要膜除去後の除去端部（例えば、レジスト膜端部）の形状精度（不要膜除去幅の均一性）が向上し、更には、不要膜除去後の不要膜残滓（レジスト残滓）の発生を防止したマスクブランクスを得ることができる。また、周縁部に補助パターン（アライメントマークや品質保証パターン等）を形成するマスク作製においては、周縁部に位置する補助パターンのパターン不良を防止することができる。
【００１５】
【発明の実施の形態】
本発明の実施の形態を、図１乃至図４を用いて詳細に説明する。
図１は、本発明の不要膜除去装置にレジスト付き基板をセットした状態における不要膜除去装置の構造を示す断面図である。
図１において、基板１は、合成石英ガラスからなる透明基板（１５２．４ｍｍ×１５２．４ｍｍ×６．３５ｍｍ）の表面にクロムを主成分とする遮光膜が形成され、さらに、この遮光膜の上にレジスト膜２が所望の膜厚にスピンコート法等で形成されたフォトマスクブランクスである。
ここで、このレジスト膜２は、本来、基板１の表面における所望の有効領域にのみ形成されていればよい。しかしながら、レジスト膜２の形成の際に、本来形成する必要のない基板１の表面の周縁部、基板側面部および場合によっては基板裏面部にまで形成されてしまう。この発明にかかる不要膜除去方法およびその装置は、これらの不要膜を除去する方法および装置である。
【００１６】
本発明の不要膜除去装置、不要膜除去方法を以下に詳細に説明する。
＜第１の実施形態＞
第１の実施形態の不要膜除去装置は、図１に示すように、基板１を面内回転するように保持する基板保持手段９と、基板１に形成された不要な膜部分を除去する薬液を供給する薬液供給手段６と、基板主表面上に不要な膜部分以外に薬液が供給されないように設けられた遮蔽部材である内カバー部材４と、内カバー部材４と共同して薬液の流路を形成する薬液案内部材である外カバー部材３とによって構成されている。
基板保持手段９は、スピンチャックを兼ね、基板保持台座１０上に設けられた、基板１の底面（裏面）および側面を複数の位置で平行に保持する複数の基板用可動保持手段５と、複数の基板支持部材１１で構成されている。基板用可動保持部材５は、基板１の中心が基板保持手段９の回転中心と一致するように、例えば、基板１の一対角方向の頂点近傍（コーナー部）に一対（２個）ずつ２箇所に配置され、基板保持手段９の回転中心から放射方向に可動し、基板１を基板保持手段９の回転中心方向に機械的に押付けるようにしている。
【００１７】
また、基板支持部材１１は、例えば、基板用可動保持手段５と他の対角線方向に複数箇所（例えば、２箇所）設けられており、基板１を支えている。
基板用可動保持手段５は、基板１が回転中に安定して保持され、且つ、不要膜除去のための薬液供給が妨げられ、基板の底面、および側面に対し点接触、または線接触するような形状となっていて、バネ機構等により基板１を押圧する構造とすることが好ましい。この基板用可動保持手段５が、基板１を機械的に押付けて固定することによって、回転中における基板１のガタツキを低減することができ、さらに基板１の中心と基板保持手段９の回転中心を一致させることができるので、不要膜除去後のレジスト膜端部の形状精度（不要膜除去幅の均一性）を向上させ、不要膜除去後の不要膜（レジスト膜）残滓の発生を抑制することができる。
【００１８】
内カバー部材４は、基板１の主表面上方からかぶせるようにして覆う形状となっている。その形状は、基板中心部から周縁にかけての大部分は、略平坦な平坦部を有し、この平坦部の両外周端が下方に略直角に折り曲げられて、側面部が形成されるようになっている。内カバー部材４は、基板１の主表面上に配置されたときに、内カバー部材の側面部の底面がある一定の間隙が形成されるように固定される。このとき、内カバー部材４の側面部の底面およびそれより外側が基板主表面における不要な部分（除去領域）となる。また、内カバー部材４の側面部以外の上記平坦部は、前記間隙の大きさよりも大きい空間が形成され、非除去領域となる。尚、内カバー部材が基板に対しある一定の間隙を形成するための固定の仕方は特に制限はない。後述する間隔調整部材を側面部の底面に設けて基板１の主表面上に載置してもよいし、基板主表面の上方から吊り下げられるように固定しても良い。内カバー部材４を上記形状とすることによって、内カバー部材４の側面部の底面と、基板主表面との間に形成された間隙に薬液が供給されたときに、薬液の表面張力によるメニスカスが働き、間隙中に薬液は満たされるが、基板主表面の非除去領域に形成された空間には薬液は流れ込まない。
【００１９】
内カバー部材が基板に対しある一定の間隙が形成されるように、内カバー部材４の側面部底面（基板主表面の不要膜除去領域）には、内カバー部材４と基板（レジスト膜）表面との間隔を調整する間隔調整部材８が設けられており、この間隔調整部材８によって、内カバー部材４の側面部底面とレジスト膜２の表面との距離が０．１ｍｍ程度の一定の距離に保持されている。この距離は、薬液が表面張力により内カバー部材４の側面部底面とレジスト膜２の表面とによって形成された間隙中にのみ伝わることができるように設定される。これにより、形成されたレジスト膜に損傷を与えてはならない所望の有効領域に薬液が侵入するのを防止することができる。
【００２０】
この間隔調整部材８は、内カバー部材の側面部底面に３箇所以上設けられている。３箇所以上とするのは、３箇所以上であれば平面を特定でき、内カバー部材４の側面部底面と基板表面との間隙が決められるからである。
間隔調整部材８は、内カバー部材４の側面部底面を機械加工等により形成してもよく、また、一定の高さを有するものを内カバー部材４の側面部底面に取りつけても良い。例えば、間隔調整部材８として、薬液に耐性のある紐状体（例えば、樹脂製の糸）で構成することができる。樹脂製の糸は入手し易いうえ、内カバー部材４の側面部底面とレジスト膜２の表面との間に挟み込むことによって内カバー部材４とレジスト膜２との間隙の大きさを一定に保つことが容易だからである。糸の太さ、即ち、内カバー部材４の側面部底面とレジスト膜２の表面との間隙の大きさｄ１は、この間隙に薬液を供給したときに、表面張力により薬液が間隙から基板中央側にはみ出すことなく、間隙中のみに満たされることが可能な大きさに設定する。好ましくは、ｄ１を０．０５〜３ｍｍとする。０．０５ｍｍ未満だと薬液が間隙に十分に侵入することが困難になり、間隙中に薬液が満たされずに除去できない部分ができる場合や、除去部分と他の部分との境界がギザギザ状態になる場合があるからである。また、３ｍｍ超だと、表面張力がうまく作用せずに薬液を間隙中に維持できなくなり、薬液が基板中央側に向かって流れ込み、本来レジスト膜が形成されていなくてはならない領域（非除去領域）まで除去あるいは一部溶解してしまうからである。
【００２１】
また、上記間隙および基板側面の不要な膜部分に薬液が十分に供給できるように、内カバー部材４と基板１の側面を覆うように外カバー部材３が設けられている。外カバー部材３と内カバー部材４とは、外カバー部材３と内カバー部材４の間にある間隔が形成されるように接続部材７で固定されており、外カバー部材３と内カバー部材４の間が薬液の流路となっており、この流路の断面積、薬液流量あるいは基板の回転数を調整することにより不要な膜部分への薬液の供給量を調整することができる。尚、外カバー部材３は、薬液供給手段によって供給される薬液が、内カバー部材４の外周を伝わって基板１の不要な膜部分に供給されるように、外カバー部材３の上方に薬液供給手段６からの薬液の供給口となる開口部が設けられている。
【００２２】
尚、図１には図示しないが、基板保持台座１０には、基板保持手段９の回転中心と、内カバー部材４、外カバー部材３の回転中心が一致するように位置決めするためのピン１２が外カバー部材３に設けられた穴１３と一定のクリアランスをもって勘合するように設けられている。
基板表面に形成された不要な膜は、薬液供給手段６によって供給される薬液によって除去される。薬液供給手段６は、例えば、ノズル形状となっており、外カバー部材３の上方に設けられた開口部と、基板１の裏面にそれぞれ設置されている。薬液は例えば、アセトン等の溶剤またはTMAH（テトラ・メリル・アンモニウム・ハイドロオキサイド）等の現像液が使用される。
【００２３】
第１の実施形態の不要膜除去方法は、上述の第１の実施形態における不要膜除去装置を使って基板１上に形成された不要な膜を、薬液供給手段６から供給される薬液によって除去する。
薬液供給手段６から供給された薬液は、内カバー部材４と外カバー部材３の間を流路として内カバー部材４の外周を伝わって、基板の表面に形成された不要な膜部分に供給される。基板１は、基板保持手段９に設けられた基板用可動保持手段５によって基板１の中心と基板保持手段９の回転中心を一致させ、且つ回転中においてもガタツキがないように機械的に固定保持される。さらに、基板保持手段９の基板保持台座１０に設けられたピン１２と外カバー部材３に設けられた穴１３との勘合によって、基板保持手段９の回転中心と外カバー部材３および内カバー部材４の中心が一致するようにしているので、基板１、内カバー部材４、外カバー部材３が一体となって偏芯や回転方向のずれがなく回転することにより、ブレや位置ずれ（重ね合わせ精度の劣化）がなく薬液によって不要膜除去が可能となる。ここで、基板１の不要な膜部分に薬液を供給するときは、基板１、内カバー部材４、外カバー部材３が回転している方が、基板１の周縁部に均一に薬液が供給できるので好ましい。尚、薬液によって溶解された不要膜は、遠心力により外方に除去される。
【００２４】
＜第２の実施形態＞
第２の実施形態の不要膜除去装置は、図２に示すように、上述の第１の実施形態において、遮蔽部材である外カバー部材３および内カバー部材４を、外カバー部材３の外側から基板保持手段９の回転中心方向に機械的に押付けて固定する遮蔽部材用可動保持手段１４を設けている点が相違する。
この遮蔽部材用可動保持手段１４は、遮蔽部材用可動保持手段１４の中心が、基板保持手段９の回転中心と一致するように、例えば、基板用可動保持手段５と他の対角線方向の頂点近傍（コーナー部）に一対（２個）ずつ２箇所に設置され、基板保持手段９の回転中心から放射方向に可動し、遮蔽部材用可動保持手段１４を外カバー部材３の側面方向から基板保持手段９の回転中心方向に機械的に押付けるようにしている。
【００２５】
この遮蔽部材用可動保持手段１４が、外カバー部材３を機械的に押付けて固定することによって、回転中における外カバー部材３および内カバー部材４の偏芯およびガタツキを抑えることができ、さらに上述の基板用可動保持手段５と組み合わせることによって、基板１、外カバー部材３および内カバー部材４の中心と、基板保持手段９の回転中心を一致させること（重ね合わせ精度を向上させること）ができるので、不要膜除去後のレジスト膜端部の形状精度（不要膜除去幅の均一性）をより一層向上させ、不要膜除去後の不要膜（レジスト膜）残滓の発生を抑制することができる。
尚、上述の実施の形態では、遮蔽部材として外カバー部材と内カバー部材を備えたものを挙げて説明したが、外カバー部材を設けずに、従来のような基板周縁部に微細な孔が多数形成された遮蔽部材を用いても構わない。
第２の実施形態の不要膜除去方法は、上述の第２の実施形態における不要膜除去装置を使って基板１上に形成された不要な膜を、薬液供給手段６から供給される薬液によって除去される。
【００２６】
＜第３の実施形態＞
第３の実施形態における不要膜除去方法は、上述の第１および第２の実施形態において、基板１上に形成される膜が、図３に示す回転塗布装置を使用して成膜することを特徴とする。図３に示す回転塗布装置を使用して成膜することにより、不要膜除去前の基板周縁部に形成されたレジスト膜の比較的厚膜な部位の幅或いは膜厚の偏りを抑えることができるので、不要膜除去後の不要膜残滓を防止することができ、さらに、不要膜除去幅の均一性を良好にすることができる。
図３は、基板１上に膜（例えば、レジスト膜）を回転塗布形成するための回転塗布装置の構造を示す断面図である。基板１を保持するための構成は、図１の不要膜除去装置と同じ構成を有しているので、その共通部分については、同じ用語を用いて、回転塗布装置について説明する。
【００２７】
基板１は基板保持手段９の上に載置され、モーターなどの回転駆動装置１５により回転する。基板１の上方には、レジスト液１８を供給するレジスト供給手段１６が設置されており、基板１が静止或いは回転しながら、基板１の表面にレジスト液１８が供給滴下され、遠心力によって基板１の表面全体にレジスト液１８が塗布される。尚、基板保持手段９の外周には、カップ１７が設けられており、飛散したレジスト液１８を回収するようになっている。
基板保持手段９上には、上述の第１の実施形態と同様の複数の基板用可動保持手段５が設けられている。この基板用可動保持手段５を用いることによって、回転塗布時の基板１の中心と基板保持手段９の回転中心を一致させることができ、また、基板１のガタツキを抑えることによって、基板全面におけるレジスト膜厚の偏りを防止でき、更に基板周縁部に形成される比較的厚膜な部位の幅或いは膜厚の偏りを抑制することができる。
従って、第３の不要膜除去方法は、上述の回転塗布装置を使用して成膜することにより、不要膜除去前の基板周縁部に形成される比較的厚膜な部位或いは膜厚の偏りを抑えることができるので、当該回転塗布工程と、上述の第１、第２の実施形態における不要膜除去装置を使用しての不要膜除去方法による不要膜除去工程とにより、更に一層、不要膜除去後の不要膜残滓を防止することができ、また、不要膜除去幅の均一性を良好にすることができる。
【００２８】
＜実施例＞
図４は、フォトマスクブランクスの製造方法において、本発明の不要膜除去工程（薬液のみによる場合）を説明するための図であり、フォトマスクブランクスの製造工程において、遮光膜等の薄膜を形成した後の一部を取り出したものである。薬液のみによるレジスト不要膜除去を採用した場合について、遮光膜等の薄膜を形成した後の主な工程としては、レジスト塗布（S101）、不要膜除去（S102）、熱処理（S103）の工程からなる。
まず、遮光膜等の薄膜が形成された基板の主表面上にレジストが回転塗布装置によって回転塗布され（S101）、その後、該レジスト塗布されたレジスト付き基板を、上述の不要膜除去装置の基板保持手段にセットする。ここで使用したレジスト種は、ポジ型化学増幅型電子線描画用レジストのＦＥＰ１７１（富士フィルムアーチ社製）である。
【００２９】
次に、基板保持手段にセットされたレジスト付き基板を、薬液案内部材である外カバー部材と、不要な部分以外に薬液が供給されないように設けられた遮蔽部材である内カバー部材とからなるカバー部材（遮蔽部材）によって覆い、レジスト付き基板と、カバー部材を一体とし所定の回転数で回転させながら、基板周縁部の不要なレジスト膜部分に有機溶剤（例えば、アセトン）を供給することによって、基板周縁部の不要膜が除去される。次いで、有機溶剤の供給を止め、前記所定の回転数より高い回転数で回転させることで、不要膜が除去された部位は回転乾燥されて、基板周縁部の不要なレジスト膜の除去は完了する（S102）。
その後、熱処理を施す（S103）ことにより、レジスト膜が基板中央の所望の有効領域にのみ形成されたフォトマスクブランクスを得ることができる。
ここで、図５は、本発明における不要膜除去工程の子細を示すフローチャートである。
【００３０】
まず、レジスト液を塗布した後のレジスト付き基板を基板保持手段にセットして上述のカバー部材を被せる。
次に、基板保持手段を回転数ｆ１（２００〜７５０ｒｐｍの範囲で調整（本実施例では５００ｒｐｍ））で回転させると同時に、薬液供給手段（ノズル）から供給量を微調整しながら薬液を供給し、基板保持手段を回転時間ｔ１（５〜３００秒の範囲で調整（本実施例では３０秒間）回転させた。これにより、薬液が基板周縁部の不要膜部分を溶解除去した（不要膜溶解除去工程）。
次に、薬液供給手段（ノズル）から薬液の供給を停止し、続いて基板保持手段を回転数ｆ２（３５０〜２５００ｒｐｍの範囲で調整（本実施例では２０００ｒｐｍ））で回転させた。これによって、不要膜が除去された部位は乾燥される（乾燥工程）。
尚、上述のレジスト塗布工程で使用する回転塗布装置を、図３に示す回転塗布装置を使用することにより、不要膜除去前の基板周縁部に形成される比較的厚膜な部位の幅或いは膜厚の偏りを抑えることができるので、不要膜除去後の不要膜残滓を防止することができ、さらに、不要膜除去幅均一性を良好にすることができる
【００３１】
上述本発明の不要膜除去装置、回転塗布装置を使用して種々のフォトマスクブランクスを作製し、不要膜除去幅均一性、レジスト残滓を評価した。その結果を表１に示す。
表１において、膜塗布装置は、レジスト膜を回転塗布する回転塗布装置を示し、偏芯を抑制するよう基板を機械的に押付けて固定する基板可動用保持手段を備えた回転塗布装置を使用した場合を「有」、基板可動用保持手段を用いず、従来の単に一定のクリアランスを設けて固定した基板保持部材を備えた回転塗布装置を使用した場合を「無」と表示した。
【００３２】
また、不要膜除去装置は、偏芯を抑制するよう基板を機械的に押付けて固定する基板用可動保持手段を備えた不要膜除去装置を使用した場合を「有」、基板用可動保持手段を用いず、従来の単に一定のクリアランスを設けて固定した基板保持部材を備えた不要膜除去装置を使用した場合を「無」と表示した。
同様に、偏芯を抑制するようカバー部材（外カバー部材）を機械的に押付けて固定する遮蔽部材用可動保持手段を備えた不要膜除去装置を使用した場合を「有」、遮蔽部材用可動保持手段を用いず、従来の単に一定のクリアランスを設けて固定したピンを備えた不要膜除去装置を使用した場合を「無」と表示した。
【００３３】
尚、ここで不要膜除去幅均一性は、基板側面より１．５ｍｍ内側の基板周縁部に形成されたレジストの不要膜を除去した際に、除去されるべき幅からのレジスト端部のずれ量で評価した。また、レジスト残滓の発生率は、不要膜除去工程における不要膜除去条件を固定したときの、レジスト残滓の発生率を示す（フォトマスクブランクス１００枚作製）。
基板周縁部におけるレジストの不要膜除去後の不要膜除去幅均一性と、基板周縁部のレジスト残滓の発生率を調べた結果、まず、膜塗布装置、不要膜除去装置において、基板用可動保持手段、遮蔽部材用可動保持手段を使用しない比較例の場合、不要膜除去幅均一性（所望の除去幅１．５ｍｍに対する最大ずれ幅）が０．２４ｍｍで、レジスト残滓の発生率は１７％であった。
次に、不要膜除去装置において、基板用可動保持手段のみを使用した実施例１は、不要膜除去幅均一性は０．１６ｍｍ（比較例の２／３）まで低減し、レジスト残滓の発生率も３％まで低減された。
次に、不要膜除去装置において、基板用可動保持手段及び遮蔽部材用可動保持手段を使用した実施例２は、不要膜除去幅均一性は０．０８ｍｍ（比較例の１／３）まで低減し、レジスト残滓の発生率も２％まで低減された。
さらに、膜塗布装置における基板用可動保持手段と、不要膜除去装置における基板用可動保持手段及び遮蔽部材用可動保持手段と、これら全てを使用した実施例３では、不要膜除去幅均一性は０．０６ｍｍ（比較例の１／４）まで低減し、レジスト残滓は全く発生しなかった。
【００３４】
【表１】

【００３５】
ここで、上記実施例ではレジストを溶解する薬液として、有機溶剤アセトンを用いたが、これに限らず、レジストの現像液等、不要膜を溶解除去できるものであればどのようなものでもよい。
カバー部材（遮蔽部材である内カバー部材、薬液案内部材である外カバー部材）を構成する材料としては、熱を伝達しにくく、薬液に対する耐性を有し、所定の機械的強度を有するものであればどのようなものであっても良い。例えば、樹脂材料、ガラス材料、セラミックス材料およびこれらの複合材料等をあげることができる。なかでも比較的熱伝達しにくく、加工が容易でかつ軽量化が容易な樹脂材料が好ましい。また、カバー部材の基板表面の不要な膜部分以外の領域を覆う部分を上記材料で構成することが好ましい。
【００３６】
また、上記実施例では、ポジ型化学増幅型電子線描画露光用レジストを用いたが、これに限らず、高分子型やノボラック系レジストの非化学増幅型レジスト、レーザー描画露光用レジスト、或いはネガ型でも適用できることは言うまでもない。
さらに、上記実施例では、遮光膜上にレジスト膜を形成するフォトマスクブランクスの製造方法の場合に適用した例について説明したが、これは、レジスト膜の下（即ち遮光膜の上）にレジスト下地反射防止膜（BARC）等を形成し、また、レジスト膜上に導電膜あるいは保護膜等を形成したフォトマスクブランクス製造方法の場合にも適用できる。その場合、BARC（レジスト下地膜）、レジスト膜、導電膜あるいは保護膜（レジスト上層膜）を実施例に記述の方法を採用し、それぞれについて不要膜の除去を実施することができる。また、その場合、遮光膜を形成した基板のほか、反射膜と吸収体等を積層した反射型マスク用基板等であってもよい。また、透光性基板上にSOG膜を形成し、SOG膜上に遮光膜パターンを形成するようにした位相シフトマスクブランクスの製造方法の場合にも適用できる。その場合、遮光膜のほかに透明導電膜、エッチングストッパー膜等の膜が設けられたものであっても良い。
【００３７】
さらに、例えば、磁気ディスク媒体の保護膜や潤滑膜の塗布、カラーフィルターの保護膜を塗布する際に形成される不要膜の除去、あるいは、液晶ディスプレー用基板上の配線の電極部に形成される絶縁膜を除去する場合にも適用できる。また、例えば、不要膜がレジストの場合は、薬液としてレジストが可溶なケトン、エステル、芳香族炭化水素、ハロゲン化炭化水素、エーテル等の液体を用いることができる。また、アルカリ現像型レジストでは、アルカリ現像液（特に高濃度の）を用いることができる。
また、不要膜除去工程として、不要な部分を露光し、現像処理して不要膜を除去する場合においては、薬液として現像液を用いることができる。
また、熱処理後の塗布膜は溶けにくいので、上記実施例では、熱処理する前に不要な膜の除去を行ったが、除去対象の膜種によっては、熱処理後に溶解が可能な場合もある。また、薬液供給手段を設ける位置は、上記実施例に限られるものではない。
【００３８】
なお、上記実施例では、基板とカバー部材とを一体にして回転させる例を掲げたが、これは必ずしも回転させる必要はない。ただし、回転させたほうが薬液を比較的早くかつ均一に間隙中に広げさせ、また、溶解された不要膜の排出を促進することができるので好ましい。
さらに、カバー部材として、上記実施例では、正方形状の基板に形成された塗布膜（レジスト膜）の周縁部を除去して正方形の塗布膜を残存させる例を挙げたが、基板の形状および残存させる塗布膜の形状は、正方形に限られるものではなく、円形、三角形、多角形その他任意の形状でもよい。
また、上記実施例では、偏芯を抑制するように、基板、カバー部材（外カバー部材）機械的に押付けて固定する可動保持手段は、基板保持手段9の回転中心から放射方向に移動するバネ機構を基板の一対角方向の頂点近傍（コーナー部）に一対（２個）ずつ２箇所に配置されて構成したがこれに限定されない。また、これら可動保持手段の可動動力機構は問わない。
【００３９】
【発明の効果】
基板と基板保持手段との偏芯やガタツキ、更には基板と遮蔽部材の偏芯やガタツキを抑制して、不要膜除去後のレジスト膜端部の形状精度（不要膜除去幅の均一性）が良好になり、かつ、不要膜除去後の不要膜残滓の発生を抑制する不要膜除去装置および不要膜除去方法、並びにこれを用いるフォトマスクブランクスの製造方法を提供することができた。
また、回転塗布方法による塗布膜の成膜工程において基板周縁部に形成される比較的厚膜な部位の幅或いは膜厚の偏りを抑えることで、不要膜除去後のレジスト膜端部の形状精度（不要膜除去幅の均一性）が良好になり、かつ、不要膜除去後の不要膜残滓の発生を防止する不要膜除去方法、並びにそれを用いるフォトマスクブランクスの製造方法を提供することができた。
【図面の簡単な説明】
【図１】本発明の第１の実施形態における不要膜除去装置に、レジスト膜付き基板をセットした状態における不要膜除去装置を示す断面図である。
【図２】本発明の第２の実施形態における不要膜除去装置に、レジスト膜付き基板をセットした状態における不要膜除去装置を示す断面図である。
【図３】本発明の第３の実施形態におけるレジスト塗布工程で使用する回転塗布装置を示す断面図である。
【図４】本発明における不要膜除去工程を説明するための図である。
【図５】本発明における不要膜除去工程の実施例を示すフローチャートである。
【符号の説明】
１・・基板、
２・・レジスト膜、
３・・外カバー部材、
４・・内カバー部材、
５・・基板用可動保持手段、
６・・薬液供給手段、
７・・接続部材、
８・・間隔調整部材、
９・・基板保持手段、
１０・・基板保持台座、
１１・・基板支持部材、
１２・・ピン、
１３・・穴、
１４・・遮蔽部材用可動保持手段、
１５・・回転駆動装置、
１６・・レジスト供給手段、
１７・・カップ、
１８・・レジスト液[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an unnecessary film removing apparatus and an unnecessary film removing method for removing an unnecessary film formed on a part of a substrate surface such as a mask blank, a semiconductor substrate, a magnetic disk substrate and a color filter, and a mask blank using the same. It relates to the manufacturing method.
[0002]
[Prior art]
In the field of manufacturing semiconductor substrates, photomasks and photomask blanks, magnetic disk substrates, color filters, etc., it is often required to remove unnecessary portions of coating films and other films formed on one main surface of the substrate. Is done.
Resist film on substrate, anti-reflective coating (BARC: Bottom Anti-Reflective Coating), resist anti-reflective coating (TARL: Top Anti-Reflective Layer), resist upper protective film, conductive film, etc. (in this specification) When a representative (generally referred to as a resist) is formed by spin coating or the like, or when they are laminated, the coating solution accumulates at the peripheral edge of the substrate surface, or the side surface of the substrate, or the back surface of the substrate in some cases A relatively thick resist film is formed on the periphery of the photomask blank.
[0003]
The resist film on the peripheral edge of the substrate is easily peeled off and dropped by contact with the container when the photomask blank is taken in and out of the container, for example. In addition, this thick film part cracks easily when it is processed with chemicals such as developer in the subsequent mask manufacturing process, and it is easy to peel off and fall off, and it becomes dust and reattaches to the photomask blank itself or various processing equipment. In the end, it may cause defects in masks (including reticles), which are products using photomask blanks as raw materials, or cause a reduction in manufacturing yield.
In addition, when a photomask blank having a resist film formed on the main surface of the substrate is attached to the exposure apparatus, the substrate peripheral portion may be supported. In this case, the substrate peripheral portion is raised. If it is, it will not be favorably supported.
Furthermore, when the exposure apparatus is an electron beam mask drawing apparatus, when the photomask blank is grounded during exposure, the light shielding film (conductive film) mainly composed of chromium under the resist film and the ground probe are good. The problem of not touching occurs.
Therefore, in such a case, it is necessary to remove an unnecessary coating film on the peripheral edge of the substrate.
[0004]
In order to solve the above problems, there is a method disclosed in Japanese Patent Laid-Open No. 2001-259502 as a technique for removing an unnecessary resist film formed on the peripheral edge of the substrate. This method of removing an unnecessary film is performed by applying a shielding member, which is a cover member in which a number of fine holes are formed in a peripheral portion (a portion located above the unnecessary film to be removed) on a substrate after coating and forming a resist film. By placing and supplying the solvent from above the shielding member, the solvent is supplied to the peripheral edge of the substrate through fine holes, and the resist film formed on the peripheral edge of the substrate is dissolved and removed. In addition, the distance between the substrate and the shielding member is set so that the solvent does not flow into the non-removed region on the center side of the substrate, so that the surface tension of the solvent is constant, and the thread is placed in the hole at the same position on each side. Adjusting member). In addition, the substrate is simply placed on a substrate holding base provided with a substrate holding member that is disposed at two corners of the substrate at two sides each with a certain clearance from the substrate side surface.
[0005]
In recent years, due to the enlargement of the effective area of the substrate, strict control of the removal area width is required. Since the conventional unnecessary film removing apparatus has the above-described configuration, the positional accuracy of the substrate relative to the substrate holding base (by the backlash and eccentricity between the substrate and the substrate holding means, and the backlash and eccentricity between the substrate and the shielding member) The overlay accuracy) and the position accuracy of the shielding member with respect to the substrate (overlay accuracy) are poor, and the shape accuracy of the resist film edge after removal of the unnecessary film (uniformity of the unwanted film removal width) is poor. The point became prominent.
1) Since the shape accuracy of the edge portion of the resist film after the unnecessary film removal at the peripheral edge portion of the substrate is poor, the appearance after the mask fabrication is impaired.
2) Since the shape accuracy of the edge of the resist film after removing the unnecessary film at the peripheral edge of the substrate is poor, it is located at the peripheral edge when the photomask is manufactured using the photomask blank from which the unnecessary film at the peripheral edge of the substrate is removed. This is a cause of pattern defects (defects, shape defects, etc.) of auxiliary patterns (alignment marks and quality assurance patterns).
3) Also in the (resist) film forming step by the spin coating method before removing the unnecessary film, the rotation holding means for supporting the substrate to be processed in the spin coating apparatus simply places the substrate to be processed. However, the resist film may be spin-coated in a state where the center of the substrate to be processed and the rotation center of the rotation holding means are shifted (eccentric), and a relatively thick film at the peripheral edge of the substrate before unnecessary film removal. Due to the deviation of the width or film thickness of such a portion, unnecessary film removal at the peripheral edge of the substrate may not be performed completely, and an unnecessary film residue may be generated.
[0006]
[Patent Document 1]
JP 2001-259502 A
[0007]
[Problems to be solved by the invention]
Therefore, the present invention solves the problems of the prior art as described above,
First, it suppresses eccentricity and backlash between the substrate and the substrate holding means, and further, eccentricity and backlash between the substrate and the shielding member, and the shape accuracy of the resist film edge after removal of the unnecessary film (uniform width of unnecessary film removal) The first object is to provide an unnecessary film removing apparatus and an unnecessary film removing method that suppress the generation of unnecessary film residues after the unnecessary film removal, and a photomask blank manufacturing method using the same. Let it be an issue.
Secondly, the shape accuracy of the resist edge after unnecessary film removal (uneven film removal width is uniform) by suppressing the eccentricity and backlash between the substrate and the substrate holding means, and further the eccentricity and backlash between the substrate and the shielding member. In addition, in the film formation process of the coating film by the spin coating method, the unevenness of the width or film thickness of the relatively thick film at the peripheral edge of the substrate is suppressed, and unnecessary film residue is generated after the unnecessary film is removed. It is a second object to provide a method for removing unnecessary films that prevents the above and a method for manufacturing photomask blanks using the same.
[0008]
The mask blank referred to in the present invention refers to both a transmissive mask blank and a reflective mask blank, and the structure thereof includes a thin film that becomes a transfer pattern to be transferred onto a substrate, a resist film, Have
A transmissive mask blank uses a light-transmitting substrate as a substrate, and a thin film to be a transfer pattern is a thin film (for example, having a light-shielding function) that causes an optical change with respect to exposure light used when transferred to a transfer target. A thin film is a photomask blank. Here, the thin film that causes an optical change with respect to the exposure light refers to a light-shielding film that blocks the exposure light, a phase shift mask that changes the phase difference of the exposure light, and the like.
Therefore, the photomask blank referred to in the present invention includes a normal photomask blank in which a light shielding film is formed as a thin film having a light shielding function, and a phase shift mask blank (halftone in which a halftone film is formed as a thin film having a light shielding function). Type phase shift mask blank), a phase shift mask blank on which a phase shift film is formed, and the like.
[0009]
The thin film having a light shielding function may be a laminate of the halftone film and the light shielding film. In addition to a thin film having a light shielding function, a phase shift mask blank in which a layer having a phase shift function is formed is included. When the layer having the phase shift function is formed by digging a light-transmitting substrate, the light-transmitting substrate is a layer having the phase shift function. Further, a phase shift layer may be formed.
The reflective mask blank is a mask blank using a low thermal expansion substrate as a substrate, and having a light reflecting multilayer film and a light absorber film serving as a transfer pattern on the substrate.
In addition to the above-described films, the mask blank includes a resist underlayer antireflection film (BARC), a resist upper layer antireflection film (TARL), a resist upper layer protective film, and a conductive layer. A film such as a film may be formed.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a movable fixing means for a substrate that is mechanically pressed and fixed so that the center of the substrate and further the shielding member coincides with the rotation center of the substrate holding means, and further the shielding. By providing the movable fixing means for the member, it is unnecessary to suppress the eccentricity and backlash between the substrate and the substrate holding means, and further, the eccentricity and backlash between the substrate and the shielding member, that is, the deterioration of each overlay accuracy. It is unnecessary to improve the shape accuracy (uniformity of unnecessary film removal width) of the removal edge (for example, resist film edge) after removal of the film, and further suppress the generation of unnecessary film residue after unnecessary film removal. A film removing apparatus and an unnecessary film removing method, and a mask blank manufacturing method using the same are provided.
Further, the film forming process before removing the unnecessary film includes a spin coating process by a spin coating apparatus, and the spin coating apparatus has a rotation holding means for rotatably holding the substrate, the center of the substrate being Substrate fixing means for mechanically pressing and fixing the substrate so as to coincide with the rotation center of the rotation holding means is provided, and the center of the substrate to be processed and the center of the rotation holding means coincide during the spin coating process. By doing so, it is possible to improve the shape accuracy of the removed portion after removing the unnecessary film by suppressing the unevenness of the width or film thickness of the relatively thick portion of the peripheral edge of the substrate before removing the unnecessary film and removing the unnecessary film. The present invention provides an unnecessary film removing method for preventing generation of unnecessary film residues after removal, and a mask blank manufacturing method. That is, the gist of the present invention is the following contents as described in the claims.
[0011]
(1) An unnecessary film removing apparatus that supplies a chemical solution only to an unnecessary portion including a peripheral portion of a film formed on a mask blank surface, and removes an unnecessary film portion formed on the mask blank, The unnecessary film removing apparatus includes: a substrate holding unit that holds the mask blank so as to rotate in-plane; a chemical solution supply unit that supplies the chemical solution; and a mask blank main surface in a removal region of the mask blank main surface; And a shielding member that covers the main surface of the mask blank so that a space larger than the gap is formed in a non-removed region of the main surface of the mask blank. The holding means is such that the center of the mask blanks is the substrate A movable holding means for a substrate for mechanically pressing and fixing the mask blanks so as to coincide with the rotation center of the holding means; The shielding member is positioned and fixed to the substrate holding means so that the rotation center of the substrate holding means and the rotation center of the shielding member coincide with each other. The chemical liquid is supplied into the gap by the chemical supply means while rotating the substrate holding means in a state where the mask blanks are mechanically pressed by the movable holding means for the substrate and fixed to the substrate holding means. An unnecessary film removing apparatus for removing an unnecessary film in a removal region of the mask blank main surface.
(2) The substrate holding means includes a movable holding means for shielding member that mechanically presses and fixes the shielding member so that the center of the shielding member coincides with the rotation center of the substrate holding means. Do (1) Unnecessary film removing apparatus described in 1.
According to this solution, the substrate and the shielding member are fixed and held so that the center of the substrate and the shielding member coincides with the rotation center of the substrate holding means. The backlash can be reduced, and as a result, the uniformity of the unnecessary film removal width can be further improved, and the occurrence of unnecessary film residues after the unnecessary film removal can be suppressed.
[0012]
(3) The gap is set to a size that allows the chemical solution to flow through the gap and to be held only in the gap (1). Or (2) Unnecessary film removing apparatus described in 1.
In the unnecessary film removing apparatus of the present invention, the gap is set to a size that allows the chemical solution to flow into the gap and to be held only in the gap. Accordingly, in the removal region of the main surface of the substrate, the meniscus is caused by the surface tension of the chemical solution in the gap formed between the substrate and the shielding member, and the chemical solution is filled (supplied) in the gap. It does not enter the space formed in the non-removed area on the surface.
In addition, the shielding member is provided with a certain gap from the main surface of the substrate and with a certain width in an unnecessary film region (removal region) formed on the main surface of the substrate, and the interval and width are adjusted. By doing so, the removal region (width) on the main surface of the substrate can be strictly controlled.
[0013]
(4) (1) to (3) An unnecessary film removing method using the unnecessary film removing apparatus according to any one of claims 1 to 4, wherein the mask blanks are placed on the substrate holding means, and at least the center of the mask blanks is centered by the substrate movable holding means. The chemical liquid is supplied by the chemical liquid supply means while rotating both the mask blanks and the shielding member so as to coincide with the rotation center of the substrate holding means, and includes a peripheral portion of the film formed on the surface of the mask blanks. An unnecessary film removing method, wherein an unnecessary film part is removed by supplying a chemical solution to the unnecessary part.
According to this solution, the movable holding means for substrates, respectively, so that the center of the substrate coincides with the rotation center of the substrate holding means, and further, the center of the shielding member coincides with the rotation center of the substrate holding means, Since the substrate and the shielding member are fixedly held by the substrate holding means by being mechanically pressed by the shielding member movable holding means, the eccentricity and backlash between the substrate and the substrate holding means during rotation, and also the substrate and the shielding member As a result, the uniformity of the unnecessary film removal width can be improved and the generation of unnecessary film residues after the unnecessary film removal can be suppressed.
(5) The film formed on the surface of the mask blank includes a coating film formed by a spin coating process using a spin coater, and the spin coater includes a rotary holding unit that holds the mask blank rotatably. It is provided with a movable holding means for a substrate that mechanically presses and fixes the mask blank so that the center of the blank coincides with the rotation center of the rotation holding means, and rotates with the center of the mask blank during the spin coating process. The unnecessary film removing method according to (4), characterized in that the centers of the holding means coincide with each other.
According to this solution, since it is possible to suppress the deviation of the width or film thickness of the relatively thick film formed on the peripheral edge of the substrate before removing the unnecessary film, it is possible to prevent unnecessary film residue, The uniformity of the unnecessary film removal width can be improved.
[0014]
(6) In a mask blank manufacturing method having a film forming process for forming a thin film to be a transfer pattern and a resist film on a substrate to be transferred to a transfer object, an unnecessary film formed in an unnecessary portion in the film forming process is formed. (4) or (5) A method for manufacturing a mask blank, comprising: an unnecessary film removing step for removing the unnecessary film according to the method described in 1.
According to this solution, the shape accuracy (uniformity of the unnecessary film removal width) of the removal end portion (for example, the resist film end portion) after the unnecessary film removal is improved, and further, the unnecessary film residue after the unnecessary film removal is improved. Mask blanks in which occurrence of (resist residue) is prevented can be obtained. Further, in mask production in which an auxiliary pattern (such as an alignment mark or a quality assurance pattern) is formed on the peripheral edge, pattern defects of the auxiliary pattern located on the peripheral edge can be prevented.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described in detail with reference to FIGS.
FIG. 1 is a cross-sectional view showing the structure of the unnecessary film removing apparatus in a state where a substrate with a resist is set in the unnecessary film removing apparatus of the present invention.
In FIG. 1, a substrate 1 includes a transparent substrate (152.4 mm × 152.4 mm × 6.35 mm) made of synthetic quartz glass and a light shielding film mainly composed of chromium formed on the surface of the light shielding film. In the photomask blank, the resist film 2 is formed to a desired film thickness by spin coating or the like.
Here, the resist film 2 should originally be formed only in a desired effective region on the surface of the substrate 1. However, when the resist film 2 is formed, the resist film 2 is formed even on the peripheral portion of the front surface of the substrate 1, the side surface portion of the substrate 1, and possibly the back surface portion of the substrate. The unnecessary film removing method and apparatus according to the present invention are a method and apparatus for removing these unnecessary films.
[0016]
The unnecessary film removing apparatus and the unnecessary film removing method of the present invention will be described in detail below.
<First Embodiment>
As shown in FIG. 1, the unnecessary film removing apparatus of the first embodiment includes a substrate holding means 9 that holds the substrate 1 so as to rotate in-plane, and a chemical solution that removes unnecessary film portions formed on the substrate 1. The chemical solution supplying means 6 for supplying the liquid, the inner cover member 4 which is a shielding member provided so as not to supply the chemical solution to the substrate main surface other than unnecessary film portions, and the flow of the chemical solution in cooperation with the inner cover member 4 It is comprised by the outer cover member 3 which is a chemical | medical solution guide member which forms a path | route.
The substrate holding means 9 also serves as a spin chuck, and is provided on the substrate holding pedestal 10. The substrate holding means 9 is provided with a plurality of substrate movable holding means 5 that holds the bottom surface (back surface) and side surfaces of the substrate 1 in parallel at a plurality of positions. Substrate support member 11. For example, the substrate movable holding member 5 has two pairs (two pieces) near the apex (corner portion) in the diagonal direction of the substrate 1 so that the center of the substrate 1 coincides with the rotation center of the substrate holding means 9. The substrate 1 is moved in the radial direction from the rotation center of the substrate holding means 9, and the substrate 1 is mechanically pressed toward the rotation center of the substrate holding means 9.
[0017]
In addition, the substrate support member 11 is provided at a plurality of locations (for example, two locations) in other diagonal directions with respect to the substrate movable holding means 5, for example, and supports the substrate 1.
The substrate movable holding means 5 is configured so that the substrate 1 is stably held during rotation, and the supply of a chemical solution for removing the unnecessary film is hindered, so that the substrate 1 is in point contact or line contact with the bottom surface and the side surface of the substrate. It is preferable that the substrate 1 be pressed by a spring mechanism or the like. The substrate movable holding means 5 mechanically presses and fixes the substrate 1 to reduce the backlash of the substrate 1 during rotation. Further, the center of the substrate 1 and the center of rotation of the substrate holding means 9 can be reduced. Since they can be matched, the shape accuracy (uniformity of unnecessary film removal width) of the resist film after unnecessary film removal is improved, and the generation of unnecessary film (resist film) residue after unnecessary film removal is suppressed. Can do.
[0018]
The inner cover member 4 is shaped to cover the main surface of the substrate 1 so as to cover it. Most of the shape from the central part of the substrate to the periphery has a substantially flat flat part, and both outer peripheral ends of the flat part are bent downward at a substantially right angle to form a side part. ing. When the inner cover member 4 is disposed on the main surface of the substrate 1, the inner cover member 4 is fixed so that a certain gap is formed with a bottom surface of the side surface portion of the inner cover member. At this time, the bottom surface of the side surface portion of the inner cover member 4 and the outside thereof are unnecessary portions (removal regions) on the main surface of the substrate. Further, the flat portion other than the side surface portion of the inner cover member 4 is formed with a space larger than the size of the gap and becomes a non-removal region. Note that there is no particular limitation on the manner in which the inner cover member is fixed to form a certain gap with respect to the substrate. An interval adjusting member to be described later may be provided on the bottom surface of the side surface portion and placed on the main surface of the substrate 1, or may be fixed so as to be suspended from above the substrate main surface. By forming the inner cover member 4 in the above shape, when a chemical solution is supplied to the gap formed between the bottom surface of the side surface portion of the inner cover member 4 and the main surface of the substrate, a meniscus due to the surface tension of the chemical solution is generated. The chemical solution is filled in the gap, but the chemical solution does not flow into the space formed in the non-removed region of the main surface of the substrate.
[0019]
The inner cover member 4 and the surface of the substrate (resist film) are formed on the bottom surface of the side surface portion (the unnecessary film removal region of the main surface of the substrate) so that a certain gap is formed between the inner cover member and the substrate. A distance adjusting member 8 for adjusting the distance between the inner cover member 4 and the surface of the resist film 2 is set at a constant distance of about 0.1 mm. Is retained. This distance is set so that the chemical solution can be transmitted only in the gap formed by the bottom surface of the side surface portion of the inner cover member 4 and the surface of the resist film 2 due to surface tension. Thereby, it is possible to prevent the chemical solution from entering a desired effective area that should not damage the formed resist film.
[0020]
The interval adjusting member 8 is provided at three or more locations on the bottom surface of the side surface portion of the inner cover member. The reason why the number is three or more is that if the number is three or more, the plane can be specified, and the gap between the bottom surface of the side surface portion of the inner cover member 4 and the substrate surface is determined.
The distance adjusting member 8 may be formed by machining the bottom surface of the side surface portion of the inner cover member 4 or may be attached to the bottom surface of the side surface portion of the inner cover member 4 with a certain height. For example, the distance adjusting member 8 can be formed of a string-like body (for example, a resin thread) that is resistant to chemicals. Resin yarn is easily available, and the gap between the inner cover member 4 and the resist film 2 is kept constant by being sandwiched between the bottom of the side surface of the inner cover member 4 and the surface of the resist film 2. Because it is easy. The thickness d1 of the thread, that is, the size d1 of the gap between the bottom of the side surface of the inner cover member 4 and the surface of the resist film 2 is such that when the chemical is supplied to this gap, The size is set such that it can be filled only in the gap without protruding. Preferably, d1 is set to 0.05 to 3 mm. If it is less than 0.05 mm, it will be difficult for the chemical solution to sufficiently enter the gap, and if the gap is not filled with the chemical solution and cannot be removed, or the boundary between the removed portion and the other portion becomes jagged. Because there are cases. If it exceeds 3 mm, the surface tension does not work well and the chemical solution cannot be maintained in the gap, and the chemical solution flows toward the center of the substrate, and the resist film must be originally formed (non-removable region). This is because it is removed or partially dissolved.
[0021]
Further, an outer cover member 3 is provided so as to cover the inner cover member 4 and the side surface of the substrate 1 so that the chemical solution can be sufficiently supplied to the gap and unnecessary film portions on the side surface of the substrate. The outer cover member 3 and the inner cover member 4 are fixed by a connecting member 7 so that a gap is formed between the outer cover member 3 and the inner cover member 4, and the outer cover member 3 and the inner cover member 4. A chemical liquid flow path is provided between the two, and the amount of chemical liquid supplied to an unnecessary film portion can be adjusted by adjusting the cross-sectional area of the flow path, the chemical liquid flow rate, or the rotation speed of the substrate. The outer cover member 3 supplies the chemical solution above the outer cover member 3 so that the chemical solution supplied by the chemical solution supply means travels along the outer periphery of the inner cover member 4 and is supplied to unnecessary film portions of the substrate 1. An opening serving as a supply port for the chemical solution from the means 6 is provided.
[0022]
Although not shown in FIG. 1, the substrate holding base 10 has pins 12 for positioning so that the rotation center of the substrate holding means 9 and the rotation centers of the inner cover member 4 and the outer cover member 3 coincide. It is provided so as to be fitted with a hole 13 provided in the outer cover member 3 with a certain clearance.
Unnecessary films formed on the substrate surface are removed by the chemical solution supplied by the chemical solution supply means 6. The chemical solution supply means 6 has, for example, a nozzle shape, and is installed on the opening provided above the outer cover member 3 and on the back surface of the substrate 1. For example, a solvent such as acetone or a developer such as TMAH (tetra-meryl-ammonium hydroxide) is used as the chemical solution.
[0023]
The unnecessary film removing method of the first embodiment removes an unnecessary film formed on the substrate 1 by using the chemical solution supplied from the chemical solution supply means 6 using the unnecessary film removing apparatus in the first embodiment described above. To do.
The chemical solution supplied from the chemical solution supply means 6 is supplied to an unnecessary film portion formed on the surface of the substrate through the outer periphery of the inner cover member 4 using the passage between the inner cover member 4 and the outer cover member 3 as a flow path. The The substrate 1 is mechanically fixed and held so that the center of the substrate 1 coincides with the center of rotation of the substrate holding means 9 by the movable holding means 5 for the substrate provided in the substrate holding means 9 and there is no rattling even during rotation. Is done. Further, the center of rotation of the substrate holding means 9, the outer cover member 3 and the inner cover member 4 are obtained by fitting the pins 12 provided on the substrate holding base 10 of the substrate holding means 9 with the holes 13 provided in the outer cover member 3. Since the substrate 1, the inner cover member 4, and the outer cover member 3 are integrated and rotate without any eccentricity or rotation direction deviation, blurring and positional deviation (overlapping accuracy). The unnecessary film can be removed by the chemical solution. Here, when supplying a chemical solution to an unnecessary film portion of the substrate 1, the chemical solution can be uniformly supplied to the peripheral portion of the substrate 1 when the substrate 1, the inner cover member 4, and the outer cover member 3 are rotating. Therefore, it is preferable. The unnecessary film dissolved by the chemical solution is removed outward by centrifugal force.
[0024]
<Second Embodiment>
As illustrated in FIG. 2, the unnecessary film removing apparatus according to the second embodiment is configured so that the outer cover member 3 and the inner cover member 4 that are shielding members are connected to the outer cover member 3 from the outside in the first embodiment described above. The difference is that a movable holding means for shielding member 14 is provided which is mechanically pressed and fixed in the direction of the center of rotation of the substrate holding means 9.
The shielding member movable holding means 14 is, for example, near the vertex in the other diagonal direction with respect to the substrate movable holding means 5 so that the center of the shielding member movable holding means 14 coincides with the rotation center of the substrate holding means 9. A pair (two pieces) are installed at two (corner portions), move in the radial direction from the rotation center of the substrate holding means 9, and the shielding member movable holding means 14 is moved from the side of the outer cover member 3 to the substrate holding means. 9 is mechanically pressed toward the center of rotation.
[0025]
The shielding member movable holding means 14 mechanically presses and fixes the outer cover member 3 to suppress eccentricity and backlash of the outer cover member 3 and the inner cover member 4 during rotation. By combining with the movable substrate holding means 5, the centers of the substrate 1, the outer cover member 3 and the inner cover member 4 can coincide with the rotation center of the substrate holding means 9 (improving the overlay accuracy). Therefore, the shape accuracy (uniformity of the unnecessary film removal width) of the resist film after removing the unnecessary film can be further improved, and the occurrence of unnecessary film (resist film) residue after removing the unnecessary film can be suppressed.
In the above-described embodiment, the description has been given with reference to the case where the shielding member includes the outer cover member and the inner cover member. However, without providing the outer cover member, a fine hole is formed in the peripheral portion of the substrate as in the prior art. A large number of shielding members may be used.
The unnecessary film removal method of the second embodiment removes an unnecessary film formed on the substrate 1 by using the chemical solution supplied from the chemical solution supply means 6 using the unnecessary film removal apparatus in the second embodiment described above. Is done.
[0026]
<Third Embodiment>
The unnecessary film removing method in the third embodiment is that the film formed on the substrate 1 is formed using the spin coater shown in FIG. 3 in the first and second embodiments described above. Features. By forming the film using the spin coater shown in FIG. 3, it is possible to suppress the unevenness of the width or film thickness of the relatively thick portion of the resist film formed on the peripheral edge of the substrate before removing the unnecessary film. Therefore, it is possible to prevent unnecessary film residues after the unnecessary film is removed, and to further improve the uniformity of the unnecessary film removal width.
FIG. 3 is a cross-sectional view showing the structure of a spin coating apparatus for spin coating a film (for example, a resist film) on the substrate 1. Since the structure for holding the substrate 1 has the same structure as that of the unnecessary film removing apparatus shown in FIG. 1, the rotation coating apparatus will be described using the same terms for the common parts.
[0027]
The substrate 1 is placed on the substrate holding means 9 and is rotated by a rotation driving device 15 such as a motor. A resist supply means 16 for supplying a resist solution 18 is installed above the substrate 1. The resist solution 18 is supplied and dropped onto the surface of the substrate 1 while the substrate 1 is stationary or rotating, and the substrate 1 is subjected to centrifugal force. A resist solution 18 is applied to the entire surface. Incidentally, a cup 17 is provided on the outer periphery of the substrate holding means 9 so as to collect the scattered resist solution 18.
On the substrate holding means 9, a plurality of substrate movable holding means 5 similar to those in the first embodiment described above are provided. By using the movable holding means 5 for the substrate, the center of the substrate 1 at the time of spin coating and the rotational center of the substrate holding means 9 can be made to coincide with each other. The uneven thickness can be prevented, and the uneven thickness or thickness of the relatively thick portion formed on the peripheral edge of the substrate can be suppressed.
Therefore, the third unnecessary film removing method forms a film using the above-described spin coating apparatus, thereby removing a relatively thick film portion or a film thickness deviation formed on the peripheral edge of the substrate before the unnecessary film removal. Therefore, unnecessary film removal is further achieved by the spin coating process and the unnecessary film removing process by the unnecessary film removing method using the unnecessary film removing apparatus in the first and second embodiments described above. Subsequent unnecessary film residue can be prevented, and the uniformity of the unnecessary film removal width can be improved.
[0028]
<Example>
FIG. 4 is a diagram for explaining the unnecessary film removal step (in the case of using only a chemical solution) of the present invention in the photomask blank manufacturing method. In the photomask blank manufacturing step, a thin film such as a light-shielding film is formed. The latter part is taken out. In the case where the resist unnecessary film removal using only a chemical solution is adopted, the main steps after forming a thin film such as a light shielding film include the steps of resist coating (S101), unnecessary film removal (S102), and heat treatment (S103). .
First, a resist is spin-coated on a main surface of a substrate on which a thin film such as a light-shielding film is formed by a spin coater (S101), and then the resist-coated substrate is used as a substrate of the above-described unnecessary film removing apparatus. Set on the holding means. The resist type used here is FEP171 (manufactured by Fuji Film Arch Co., Ltd.), a positive chemically amplified electron beam drawing resist.
[0029]
Next, the resist-attached substrate set in the substrate holding means is a cover comprising an outer cover member that is a chemical guide member and an inner cover member that is a shielding member provided so that the chemical solution is not supplied to other than unnecessary portions. Covering with a member (shielding member), supplying an organic solvent (for example, acetone) to an unnecessary resist film portion on the peripheral edge of the substrate while integrally rotating the substrate with the resist and the cover member at a predetermined rotation speed, Unnecessary films on the peripheral edge of the substrate are removed. Next, the supply of the organic solvent is stopped, and the portion where the unnecessary film is removed is rotated and dried by rotating at a rotation speed higher than the predetermined rotation speed, and the removal of the unnecessary resist film on the peripheral edge of the substrate is completed. (S102).
Thereafter, by performing heat treatment (S103), a photomask blank in which a resist film is formed only in a desired effective region at the center of the substrate can be obtained.
Here, FIG. 5 is a flowchart showing details of the unnecessary film removing step in the present invention.
[0030]
First, the resist-coated substrate after applying the resist solution is set on the substrate holding means, and the above-described cover member is covered.
Next, the substrate holding means is rotated at a rotation speed f1 (adjusted in the range of 200 to 750 rpm (500 rpm in this embodiment)), and at the same time, the chemical solution is supplied while finely adjusting the supply amount from the chemical solution supply means (nozzle). The substrate holding means was rotated for a rotation time t1 (adjusted in the range of 5 to 300 seconds (30 seconds in the present embodiment). Thereby, the chemical solution dissolved and removed the unnecessary film portion on the peripheral edge of the substrate (unnecessary film dissolution and removal). Process).
Next, the supply of the chemical solution from the chemical solution supply means (nozzle) was stopped, and then the substrate holding means was rotated at a rotation speed f2 (adjusted in the range of 350 to 2500 rpm (2000 rpm in this embodiment)). Thereby, the part from which the unnecessary film is removed is dried (drying step).
In addition, by using the spin coater shown in FIG. 3 as the spin coater used in the above resist coat process, the width or film of a relatively thick film formed on the peripheral edge of the substrate before unnecessary film removal. Since uneven thickness can be suppressed, unnecessary film residue after unnecessary film removal can be prevented, and the uniformity of unnecessary film removal width can be improved.
[0031]
Various photomask blanks were prepared using the above-described unnecessary film removing apparatus and spin coating apparatus of the present invention, and the unnecessary film removal width uniformity and resist residue were evaluated. The results are shown in Table 1.
In Table 1, the film coating apparatus is a spin coating apparatus that spin-coats a resist film, and a spin coating apparatus provided with a substrate moving holding means that mechanically presses and fixes the substrate to suppress eccentricity is used. In the case of “Yes”, the case of using the conventional spin coater including the substrate holding member fixed with a fixed clearance without using the substrate moving holding means is indicated as “No”.
[0032]
In addition, the unnecessary film removing apparatus is “Yes” when the unnecessary film removing apparatus provided with the movable holding means for the substrate that mechanically presses and fixes the substrate so as to suppress the eccentricity. The case where the conventional unnecessary film removing apparatus including the substrate holding member fixed with a fixed clearance is used is indicated as “none”.
Similarly, when using an unnecessary film removal device equipped with a movable holding means for shielding member that mechanically presses and fixes a cover member (outer cover member) to suppress eccentricity, “Yes”, movable for shielding member The case where the conventional film removing device including the pin fixed with a fixed clearance is used without using the holding means is indicated as “none”.
[0033]
The unnecessary film removal width uniformity is the amount of deviation of the resist edge from the width to be removed when the unnecessary film of the resist formed on the peripheral edge of the substrate 1.5 mm inside the substrate side surface is removed. It was evaluated with. The resist residue generation rate indicates the resist residue generation rate when the unnecessary film removal conditions in the unnecessary film removal step are fixed (manufacture of 100 photomask blanks).
As a result of examining the uniformity of the unnecessary film removal width after removing the unnecessary film of the resist on the peripheral edge of the substrate and the occurrence rate of the resist residue on the peripheral edge of the substrate, first, in the film coating apparatus and the unnecessary film removing apparatus, the movable holding means for the substrate In the comparative example in which the movable holding means for the shielding member is not used, the unnecessary film removal width uniformity (maximum deviation width with respect to the desired removal width of 1.5 mm) is 0.24 mm, and the resist residue generation rate is 17%. It was.
Next, in Example 1 using only the movable holding means for the substrate in the unnecessary film removal apparatus, the uniformity of the unnecessary film removal width is reduced to 0.16 mm (2/3 of the comparative example), and the resist residue generation rate Was also reduced to 3%.
Next, in Example 2 using the movable holding means for the substrate and the movable holding means for the shielding member in the unnecessary film removing apparatus, the uniformity of the unnecessary film removal width is reduced to 0.08 mm (1/3 of the comparative example). The occurrence rate of resist residues was also reduced to 2%.
Further, in Example 3, in which the movable movable means for the substrate in the film coating apparatus, the movable movable means for the substrate and the movable holding means for the shielding member in the unnecessary film removing apparatus, and all of these are used, the unnecessary film removal width uniformity is 0. It was reduced to 0.06 mm (1/4 of the comparative example), and no resist residue was generated.
[0034]
[Table 1]

[0035]
Here, in the above embodiment, the organic solvent acetone is used as the chemical solution for dissolving the resist. However, the present invention is not limited to this, and any solvent may be used as long as it can dissolve and remove unnecessary films, such as a resist developer.
As a material constituting the cover member (the inner cover member which is a shielding member, the outer cover member which is a chemical solution guide member), it is difficult to transmit heat, is resistant to the chemical solution, and has a predetermined mechanical strength. Anything is acceptable. For example, a resin material, a glass material, a ceramic material, a composite material thereof, and the like can be given. Among them, a resin material that is relatively difficult to transfer heat, is easy to process, and is easy to reduce in weight is preferable. Moreover, it is preferable to comprise the part which covers areas other than the unnecessary film | membrane part of the substrate surface of a cover member with the said material.
[0036]
In the above embodiment, a positive chemically amplified electron beam lithography resist is used. However, the present invention is not limited to this, and a non-chemically amplified resist such as a polymer type or novolak resist, a laser lithography exposure resist, or a negative resist is used. Needless to say, it can also be applied to molds.
Further, in the above embodiment, the example applied to the photomask blank manufacturing method in which the resist film is formed on the light shielding film has been described. This is because the resist underlayer is formed under the resist film (that is, on the light shielding film). The present invention can also be applied to a photomask blank manufacturing method in which an antireflection film (BARC) or the like is formed and a conductive film or a protective film is formed on the resist film. In that case, the method described in the examples for BARC (resist undercoat film), resist film, conductive film or protective film (resist upper layer film) can be adopted, and unnecessary films can be removed for each. In that case, in addition to the substrate on which the light shielding film is formed, a reflective mask substrate in which a reflective film and an absorber or the like are laminated may be used. Further, the present invention can be applied to a method of manufacturing a phase shift mask blank in which an SOG film is formed on a light-transmitting substrate and a light shielding film pattern is formed on the SOG film. In that case, a film such as a transparent conductive film or an etching stopper film may be provided in addition to the light shielding film.
[0037]
Further, for example, it is formed on the electrode part of the wiring on the substrate for liquid crystal display, or the removal of an unnecessary film formed when the protective film or lubricating film of the magnetic disk medium is applied, or the protective film of the color filter is applied. It can also be applied when removing the insulating film. For example, when the unnecessary film is a resist, a liquid such as a ketone, ester, aromatic hydrocarbon, halogenated hydrocarbon, or ether in which the resist is soluble can be used as the chemical solution. In the case of an alkali development type resist, an alkali developer (particularly high concentration) can be used.
In the unnecessary film removing step, when an unnecessary portion is exposed and developed to remove the unnecessary film, a developer can be used as a chemical solution.
Further, since the coating film after the heat treatment is difficult to dissolve, in the above embodiment, unnecessary films are removed before the heat treatment. However, depending on the film type to be removed, the film may be dissolved after the heat treatment. The position where the chemical solution supply means is provided is not limited to the above embodiment.
[0038]
In the above embodiment, the example in which the substrate and the cover member are rotated together is described, but it is not always necessary to rotate the substrate and the cover member. However, the rotation is preferable because the chemical solution can be spread in the gap relatively quickly and uniformly, and the discharge of the dissolved unnecessary film can be promoted.
Furthermore, as the cover member, in the above-described embodiment, the example in which the peripheral portion of the coating film (resist film) formed on the square substrate is removed to leave the square coating film is described. The shape of the coating film to be applied is not limited to a square, but may be a circle, a triangle, a polygon, or any other shape.
Further, in the above embodiment, the movable holding means that mechanically presses and fixes the substrate and cover member (outer cover member) so as to suppress eccentricity is a spring that moves in the radial direction from the rotation center of the substrate holding means 9. Although the mechanism is configured to be arranged in two locations in the vicinity of the apex (corner portion) in the diagonal direction of the substrate at two pairs (two), the present invention is not limited to this. Moreover, the movable power mechanism of these movable holding means does not matter.
[0039]
【The invention's effect】
Suppressing the eccentricity and backlash between the substrate and the substrate holding means, as well as the eccentricity and backlash between the substrate and the shielding member, and improving the shape accuracy of the resist film edge after removal of the unnecessary film (uniformity of unnecessary film removal width) It was possible to provide an unnecessary film removing apparatus and an unnecessary film removing method that suppresses the generation of unnecessary film residues after the unnecessary film removal, and a photomask blank manufacturing method using the same.
In addition, the shape accuracy of the resist film edge after removing the unnecessary film is suppressed by suppressing the unevenness of the width or film thickness of the relatively thick film formed on the peripheral edge of the substrate in the coating film forming process by the spin coating method. It is possible to provide an unnecessary film removal method that improves the uniformity of the unnecessary film removal width and prevents the generation of unnecessary film residues after the unnecessary film removal, and a photomask blank manufacturing method using the same. It was.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an unnecessary film removing apparatus in a state where a substrate with a resist film is set in the unnecessary film removing apparatus according to the first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing an unnecessary film removing apparatus in a state where a substrate with a resist film is set in the unnecessary film removing apparatus according to a second embodiment of the present invention.
FIG. 3 is a cross-sectional view showing a spin coater used in a resist coating process in a third embodiment of the present invention.
FIG. 4 is a view for explaining an unnecessary film removing step in the present invention.
FIG. 5 is a flowchart showing an example of an unnecessary film removing step in the present invention.
[Explanation of symbols]
1 ・ Board,
2..Resist film,
3. Outer cover member,
4 .. Inner cover member
5 .. Movable holding means for substrate,
6. Chemical solution supply means,
7. Connection member,
8. Spacing adjustment member,
9 .. Board holding means,
10 .. Board holding base,
11 .. Board support member,
12. Pin,
13..Hole,
14 .. Movable holding means for shielding member,
15..Rotary drive device,
16..Resist supply means,
17 ・ Cup
18..Resist solution

Claims

An unnecessary film removing device that removes an unnecessary film portion formed on the mask blank by supplying a chemical solution only to an unnecessary portion including a peripheral portion of the film formed on the mask blank surface,
The unnecessary film removing apparatus is
Substrate holding means for holding the mask blanks so as to rotate in-plane;
Chemical supply means for supplying the chemical,
In the removed region of the mask blank main surface, a certain gap is formed with the mask blank main surface, and in the non-removed region of the mask blank main surface, a space larger than the gap is formed. A shielding member covering the main surface,
The substrate holding means includes movable holding means for a substrate that mechanically presses and fixes the mask blanks so that the center of the mask blanks coincides with the rotation center of the substrate holding means,
The shielding member is positioned and fixed to the substrate holding means so that the rotation center of the substrate holding means and the rotation center of the shielding member coincide with each other .
While supplying the chemical liquid into the gap by the chemical liquid supply means while rotating the substrate holding means in a state where the mask blanks are mechanically pressed by the movable holding means for the substrate and fixed to the substrate holding means, An unnecessary film removing apparatus for removing an unnecessary film in the removal region of the mask blank main surface.

The substrate holding means includes a movable holding means for shielding member that mechanically presses and fixes the shielding member so that the center of the shielding member coincides with the rotation center of the substrate holding means. The unnecessary film removing apparatus according to claim 1 .

The gap flows into the gap the chemical is conveyed through the gap, and, to claim 1 or claim 2, characterized in that only is set to a size that can be retained in the gap The unnecessary film removal apparatus as described.

4. An unnecessary film removing method using the unnecessary film removing apparatus according to claim 1 , wherein the mask blanks are placed on the substrate holding means, and at least the substrate movable holding means. The mask blanks and the shielding member are rotated together so that the center of the mask blanks coincides with the rotation center of the substrate holding means, and the chemical solution is supplied by the chemical solution supply means, and is formed on the mask blank surface. An unnecessary film removing method comprising: removing an unnecessary film portion by supplying a chemical solution to an unnecessary portion including a peripheral portion of the film.

The film formed on the surface of the mask blank includes a coating film formed by a spin coating process using a spin coater, and the spin coater includes a rotary holding unit that holds the mask blank rotatably. It is provided with a movable holding means for a substrate that mechanically presses and fixes the mask blank so that the center of the blank coincides with the rotation center of the rotation holding means, and rotates with the center of the mask blank during the spin coating process. 5. The method for removing an unnecessary film according to claim 4 , wherein the centers of the holding means coincide with each other.

In a mask blank manufacturing method having a film forming process for forming a thin film to be a transfer pattern and a resist film on a substrate to be transferred to a transfer object, an unnecessary film formed in an unnecessary portion in the film forming process is formed. 6. A method for manufacturing a mask blank, comprising: an unnecessary film removing step of removing with the unnecessary film removing method according to claim 4 or 5 .