JP3586491B2 - X-ray mask and method of manufacturing X-ray mask - Google Patents

Description

【００９８】
図２はエッチングマスクの膜厚とＸ線吸収体のパターン形成の関係を示す図で、図中（ａ）は、Ｘ線吸収体４上にｄｅの厚さのエッチングマスクが形成され、その寸法変動はエッチングマスクの厚さにほぼ相当し、ｄｅである。Ｘ線吸収体をエッチングでパターニングする場合、さらに、このエッチングマスクが理想的に異方性を有し、側壁の角度が９０゜で形成された場合、さらにこのエッチングマスクを用いてＸ線吸収体の側壁がサイドエッチの影響を受けないならば、Ｘ線吸収体のエッチング後の寸法精度は極めて良くなる。しかし、エッチングマスクが等方的にエッチングされてパターンが形成されると、図２中（ａ）のような形状となり、この形状を有したエッチングマスクを用いてＸ線吸収体をエッチングすると、図２中（ｂ）のように精度の劣ったＸ線吸収体パターンしか得ることができない。さらに、図２中（ｂ）においては、Ｘ線吸収体のエッチングが完了すると同時にエッチングマスクもエッチングされて消滅するという最もエッチング条件的に厳しい場合である。この場合、パターン寸法は最小のパターン寸法（ｄｌ）とエッチングマスクの厚さｄｅにより、ｄｌ±ｄｅと記述され、エッチングマスクの厚さｄｅは同時にパターンの寸法変動を示す。ここで、許容される寸法変動はｄｌ×ａ／１００（ａは必要とされるパターン要求精度％）となる。従って、エッチングマスクが等方的にエッチングされるという最も厳しい条件より、エッチングマスクの厚さは、エッチング選択比を考慮して、Ｘ線吸収体の厚さ／選択比が最低限必要である。また、寸法精度を考慮すると、パターン最小寸法×要求精度／１００以下でよいことがわかる。これは、エッチングマスクが十分厚い時、Ｘ線吸収体のエッチングを行うことができるが、エッチングマスクパターン自身の精度が低くなり、その精度がＸ線吸収体の精度に影響を与えるため、精度の点ではできるだけエッチングマスクの厚さは可能な範囲で薄い方が良いということを示唆している。
【００９９】
また、最小パターン寸法０．１μｍ、必要な精度１０％、Ｘ線吸収体の厚さ０．５μｍとするとエッチングマスクの厚さは０．０１μｍ以下にすればよく、このとき、エッチング選択比は少なくとも５０以上必要である。このように、エッチング選択比の最適化を行うこともできる。
【０１００】
実施例２．
以下、本発明の他の実施例について図を用いて説明する。図３は、この発明の他の実施例によるＸ線マスクの構造を示す断面図である。図において、５ａはタングステン（Ｗ）からなるエッチングマスク（ａ）で厚さは０．０１μｍ、５ｂはクロム（Ｃｒ）からなるエッチングマスク（ｂ）で厚さは０．０３μｍである。なお、ここでは最小パターン寸法は０．１μｍ、寸法精度１０％である。なお、Ｘ線吸収体４の膜厚は０．５μｍである。
【０１０１】
このように、エッチングマスクを多層にすると、実施例１のような単層の場合に比べて、精度の高いエッチングが可能となる。実施例１において、述べたが、エッチングマスクが単層の場合はエッチングマスクを高精度にエッチングするには薄い方がよい。しかし、エッチングマスクを薄くすると、エッチングマスクとＸ線吸収体のエッチング選択比を大きくする必要があり、Ｘ線吸収体のエッチングが困難になる。これに対しエッチングマスクが多層の場合は、レジストの直下に厚さの制御されたエッチングマスクを配置し、精度よくエッチングし、パターニングし、それをマスクに順次下に配置された層をエッチングしていくと、パターン精度が維持されたまま、Ｘ線吸収体にとって厚いエッチングマスクが形成されることになる。
【０１０２】
次に、具体的な例で説明する。図３において、エッチングマスク（ｂ）５ｂとエッチングマスク（ａ）５ａの選択比は約１０であり、また、Ｘ線吸収体４とエッチングマスク（ｂ）５ｂの選択比は約１００である。エッチングマスクが多層の場合最上層のエッチングマスクのＸ線吸収体に対する選択比は接する層間の選択比の積で表されることから、エッチングマスク（ａ）５ａのＸ線吸収体４に対する選択比はそれらの選択比の積となり、約１０００である。すなわち、Ｘ線吸収体の厚さと選択比１０００より、エッチングマスク（ａ）５ａの厚さは０．５ｎｍであればよい。ここで、エッチング条件としてパターン精度の一番劣る条件、等方性エッチングが行われた場合を考慮しても、エッチングマスク（ａ）５ａの厚さの上限０．０１μｍ以下に設定すればよい。このように、多層のエッチングマスクを用いることにより、レジスト直下のエッチングマスクとＸ線吸収体との選択比は大きくなり、従って、精度の高いエッチングパターンを得ることができる。
【０１０３】
実施例３．
以下、本発明の一実施例について図を用いて説明する。図４は、この発明の一実施例によるＸ線マスクのエッチング方法を示したものである。図において、レジストパターン６’からエッチングストッパ９までの構造を示しており、それより下に配置するメンブレン等は省略してある。図中（ａ）はレジストパターン、（ｂ）はエッチングマスク５を等方的にエッチングした時の状態、（ｃ）はＸ線吸収体をエッチングした時の状態を示した図である。この図のように、エッチングマスク５を等方的にエッチングすると、エッチングマスクの側壁が斜めになるため、その状態でＸ線吸収体をエッチングすると、Ｘ線吸収体の側壁も斜めになる。このように、パターンの場所によりＸ線吸収体の厚さが異なると、そこを通過するＸ線の位相が変化する（Ｘ線露光の際の位相シフト効果）。そのため、パターンのエッジ部で、Ｘ線の回折現象によりボケが緩和され、微細パターンが転写できるようになる。
【０１０４】
実施例４．
以下、本発明の一実施例について説明する。図１において、エッチングマスク５もしくはエッチングストッパ９として白金もしくは白金の化合物を用いると、タングステンもしくはタングステンを主成分とするＸ線吸収体のエッチングが容易になる。これはタングステンを含むＸ線吸収体のエッチングに際しては主にフッ素系のガスを用いることになり、また、白金を含むエッチングマスクに際しては塩素系のガスを用いることになり、その際、タングステンは塩素系のガスではエッチングされにくく、また、白金はフッ素系のガスではエッチングされにくいため、互いにエッチングの選択比が大きくなるためである。なお、エッチングストッパとして白金系の物質を用いた場合には、最後にエッチングストッパの除去を行う必要がある。白金はタングステンに対し、エッチングが容易になるばかりでなく、Ｘ線吸収体として用いることができるため、エッチングマスクやパターン下のエッチングストッパはＸ線吸収体としての作用も有する。
【０１０５】
実施例５．
以下、本発明の別の実施例について説明する。図１において、エッチングマスク５やエッチングストッパ９にクロムの窒化物やクロムの窒化酸化物を用いると、Ｘ線吸収体のエッチングが容易になる。これはタングステン系がフッ素系のガス、クロム系が塩素系のガスでエッチングされ易く、その逆のガスでは互いにエッチングされにくいことによる。また、クロムの窒化酸化膜は透明であるため、エッチングストッパ兼ＡＲコートとしても用いることができる。そのため、アライメント光の透過率が上昇し、アライメントが容易になり、また、エッチングストッパの除去は行わなくても良いため、工程を簡略化することができる。
【０１０６】
実施例６．
以下、本発明の一実施例について図を用いて説明する。図５は、この発明の実施例によるＸ線マスクの製造装置の一つであるエッチング装置の全体構成図である。本装置はＥＣＲエッチング装置で、真空容器中に導入されたエッチングガスを真空容器の外側に配置した電磁コイルにより電子に運動エネルギを与え、サイクロトロン共鳴によりイオン化率の高いプラズマを生じさせ、そのプラズマにより被対象物をエッチングするものである。図６は、この発明の実施例によるＸ線マスクの製造装置の構成の一部で、エッチングの被対象物であるＸ線マスク用ウエハを搭載するステージを中心とした構成を示したものである。図において、１１は銅やアルミニウムのような熱伝導率の高い金属材質からなるパッキン、１２は冷却ステージ、１３はウエハ押え、１４は冷却用のガス穴である。また、図５中矢印はガスの流れを表し、ａ部は冷却ステージ裏面からのガスの洩れ箇所を示す。
【０１０７】
図６に示すように、Ｘ線マスクの冷却ステージ１２とウエハ押え１３に接する部分にパッキン１１を介在させる。このような構成にしてＸ線マスクのパターニングを行うと冷却用ガスのリークが少なく、冷却効率が上昇する。例えば、処理圧力１ｍｍＴｏｒｒでのエッチングの際、従来は冷却ガスを１ｓｃｃｍ流して冷却ガスの圧力が０．５Ｔｏｒｒ程度しか得られなかったが、本発明のパッキンを用いることにより冷却ガスの圧力を２Ｔｏｒｒ程度まで、向上させることができ、その結果圧力を一定に制御できたので、熱伝導も一定に保たれ冷却効率が向上した。なお、ウエハ１と冷却ステージ１２との隙間が０．１ｍｍの時、冷却ガスを１〜２Ｔｏｒｒに維持できれば、所望の冷却が可能となる。
【０１０８】
なお、本図中ではパッキン１１はＸ線マスク上面、すなわちウエハ押え１３に接する面にまで達しているが、マスク裏面すなわち冷却ステージ１２に接する面のみでもよい。ただし、マスク上面にまでパッキンを回り込ませると、パッキンのＸ線マスクへの固定がよく、ハンドリングの際パッキンが脱離せず、毎回新しいパッキンを着脱することになり、ガスがより洩れにくくなり、さらに冷却効率が上昇する。
【０１０９】
実施例７．
以下、本発明の別の実施例について図を用いて説明する。図７はこの発明の他の実施例によるＸ線マスクの製造装置であるエッチング装置の構成の一部を示したものである。図において、１５は高分子膜である。なお、この膜はレジストなどと同様にスピナー等で塗布したり、もしくはフィルム状の膜を切りとって張り付けたり、グリスなどを裏面に塗ってもよい。
【０１１０】
このような構成にしてエッチングを行うと、高分子膜がウエハとステージ間の微妙な溝（凹凸）を埋めるため、冷却用ガスの洩れが少なく、冷却効率を上げることができ、Ｘ線吸収体のエッチング形状を良くすることができる。
【０１１１】
実施例８．
以下、本発明の一実施例について図を用いて説明する。図８はこの発明の実施例によるＸ線マスクの製造装置であるエッチング装置の構成の一部を示す。図において、１６は冷却台、１７はスペーサである。図中（ａ）はバックエッチ済みのＸ線マスクを搭載した場合、（ｂ）はウエハ状態のＸ線マスクを搭載した場合を示している。図９はこの発明の他の実施例によるエッチング装置の構成の一部を示す。図９ではサポートリング８が取り付けられた状態のＸ線マスクを搭載した場合の構成を示している。
【０１１２】
このようにＸ線マスクの裏面にスペーサ１７を配置し、冷却ステージ１２とウエハ１との熱伝導を向上させる。このような構成で、エッチングを行うと、種々の形状のＸ線マスクに対応でき、スペーサ１７の高さを替えたり、また、冷却ステージ１２の形状を変えるだけでエッチングが可能となる。そのため、Ｘ線マスクの形状にこだわることなく、作製プロセスを選択できる。なお、これらのスペーサや冷却ステージは接触面積が大きい程、熱伝達のロスが低減するので、表面は平滑な方がよい。また、スペーサを隙間に合致させるためには、スペーサの寸法精度も高い方がよい。
【０１１３】
実施例９．
以下、本発明の一実施例について図を用いて説明する。図１０は、この発明の実施例によるＸ線マスクの製造方法を示す工程図である。図において、１８は炭素を含む膜である。なお、図中（ａ）はエッチング前の状態、（ｂ）はエッチングマスク５をエッチングし、その後Ｘ線吸収体のエッチングが終った状態、（ｃ）はエッチングが終った時点で、炭素を含むガスを導入して、ＣＶＤ法で成膜してもよいし、スパッタ法で形成してもよい。また、エッチングガスに含まれる炭素濃度を変化させてエッチングに連続して成膜すると、工程が簡略化できる。このような、炭素系の膜を形成し、光電子やオージェ電子等の２次電子発生防止用の膜を簡単に形成することができる。なお、ここでは炭素膜を用いているが、Ｘ線との吸収断面積の小さな物質、例えば、軽元素であればよい。ただし、Ｘ線の吸収波長によって吸収断面積は大きく異なり、軽元素においても、Ｋ殻やＬ殻の吸収端であれば、Ｘ線の吸収が大きくなるため、Ｘ線の使用波長によってはその点を考慮して物質を選定すればよい。
【０１１４】
実施例１０．
以下、本発明の一実施例について説明する。図１０において、Ｘ線吸収体がタングステンを含む場合、このＸ線吸収体のエッチングには、ＳＦ_６やＣＦ_４などのフッ素を含むガスが用いられる。その際、例えば、ＳＦ_６にＣＨＦ_３を添加してエッチングを行う。例えば、図５のＥＣＲエッチング装置を用い、ＳＦ_６とＣＨＦ_３の流量比をＳＦ_６／ＣＨＦ_３＝１／１〜１／１０でエッチングを行う。このとき、炭素系の析出物がパターンの側壁に付着し、エッチングに対して側壁を保護するため、異方性の高いエッチングを行うことができる。このようにして、エッチングを行い、パターニングが終了した時点でＣＨＦ_３の濃度を上げる。例えば、流量比でＳＦ_６／ＣＨＦ_３＝１／２０〜０／２０にすると、炭素系の析出物が多くなり、パターンを覆うようになる。そのため、光電子防止用の膜を簡単に成膜できるようになる。
【０１１５】
実施例１１．
以下、本発明の一実施例について説明する。例えば、図１において、通常はエッチングマスク５とＸ線吸収体４もしくは、Ｘ線吸収体４とエッチングストッパ９の界面が原子レベルの単位で互いに混入する。互いに混入した状態で、選択比が高く、異方性の高いエッチングを行うと、残渣発生の原因となる。そのため、互いに混入しないようにすると残渣発生を抑えることができる。
【０１１６】
図１において、エッチングストッパ９、Ｘ線吸収体４、エッチングマスク５を成膜する際、一般的には工程の簡略化のためこれらの連続した２層以上を同一装置で連続的に成膜している。しかし、通常は真空状態で成膜するために、成膜が完了した時点では表面は活性な状態であり、そのまま連続して同一装置で成膜すると、活性な界面のため互いに拡散し、原子レベルで混合してしまう。該混合層を有した状態で、異方性の高いエッチングを行うと、残渣が発生しやすくなる。そのため、同一装置で連続的に成膜せず、成膜後一度大気中に曝し、酸化や吸着等により表面の活性度の低い層（数ｎｍ）を形成し、該活性度の低い層を拡散抑制層とすることにより、次の成膜を行うと原子レベルでの混入がなくなり、残渣発生を抑制できる。
【０１１７】
実施例１２．
以下、本発明の一実施例について説明する。図１において、通常、Ｘ線吸収体４、エッチングマスク５を成膜した後、応力制御のため２００〜４００℃でのアニールを行っている。しかし、この方法では、アニール工程のためＸ線吸収体４とエッチングマスク５の界面が拡散し、その結果界面が混合し、数１０ｎｍの拡散層が形成されていた。この拡散層でエッチング条件が変化するため、エッチング時の残渣が発生し易くなる。そこで、応力制御のためのアニールをＸ線吸収体成膜後に行い、拡散層をなくすとともに、Ｘ線吸収体の表面にアニールによる数原子層（数ｎｍ）の表面酸化層を形成し、これを拡散抑制層とする。これにより、しかる後にエッチングマスクの成膜を行うと、界面が互いに混入するのが抑制され、残渣発生を防止することができる。
【０１１８】
実施例１３．
以下、本発明の一実施例について図を用いて説明する。図１１は、この発明の他の実施例によるＸ線マスクの断面構造を示したものである。図において、１９は吸収体のエッチング条件と同じ条件でエッチングされる薄膜で、例えば、タンタル（Ｔａ）である。この薄膜１９があると、エッチングマスク５とＸ線吸収体４、もしくはＸ線吸収体４とエッチングストッパ９（通常ＩＴＯ）が互いに混入しない。また、この薄膜１９は吸収体と同じ条件でエッチングされるため、通常の吸収体のエッチングを行えばよい。さらに、Ｔａは塩素系のガスでもフッ素系のガスでも比較的容易にエッチングされるため、Ｔａに起因する混合層が形成されても容易にエッチング除去される。さらに、この薄膜１９があることにより、残渣発生を抑えることができる。
【０１１９】
実施例１４．
以下、本発明の一実施例について説明する。図１１において、タングステンを含む吸収体を用いる際、図中の薄膜１９としてＳＯＧ（ｓｐｉｎ−ｏｎ−ｇｌａｓｓ）などのシリコンを含む膜を用いると、この膜はタングステンと同様な条件でエッチングができ、そのエッチング速度はタングステンのそれよりわずかに速い。そのため、ＳＯＧ層は等方的にエッチングされやすいためサイドエッチがはいりやすい。そのため、残存エッチングマスクによる吸収体の残渣もシリコンを含む膜１９のサイドエッチによって、残存エッチングマスクが落ちやすく、その結果吸収体の残渣がエッチングされる。また、吸収体とエッチングストッパの間の薄膜１９もサイドエッチが入るため、吸収体の残渣が倒れやすく、その結果残渣自身が容易にエッチングされる。そのため、残渣発生を抑えることができる。
【０１２０】
実施例１５．
以下、本発明の一実施例について説明する。図１において、Ｘ線吸収体４の表面に０．１μｍＲｍａｘ以上の凹凸がある時、そのＸ線吸収体４上にエッチングマスク５を成膜し、レジスト６のパターニング後にエッチングマスク５のエッチングを行うと、凹部にエッチングマスク５の材料が残りやすい。その結果、Ｘ線吸収体４のエッチングを行うと、Ｘ線吸収体４の残渣が発生し易くなる。そのため、Ｘ線吸収体４の表面が少なくとも０．０５μｍＲｍａｘ以下の平滑面になるように成膜したり、また、アモルファス状の吸収体を成膜すれば表面は比較的平滑に成膜できる。また、通常の吸収体は柱状構造の薄膜であるため、表面の凹凸が大きいが、この状態で、等方成エッチングを行って表面を平滑にしたり、吸収体の表面を研磨して平滑にし、その後、エッチングマスク５を成膜すれば、凹部に残るエッチングマスク５がなくなるため、Ｘ線吸収体４のエッチングの際、残渣の発生を抑制することができる。
【０１２１】
実施例１６．
以下、本発明の一実施例について説明する。図１において、エッチングマスク５がわずかでも残っていると、Ｘ線吸収体４のエッチングの際異方性の高いエッチングを行うと吸収体の残渣が発生する。図１２は、凹部においてエッチングマスクが残り、残渣が発生するプロセスと、発生する残渣を除去する工程を示したものである。図において、工程（ａ）では凹凸のあるＸ線吸収体４の上にエッチングマスク５およびパターニングされたレジスト膜６が形成されている。Ｘ線吸収体４の凹凸にならってエッチングマスク５も凹凸が形成されている。工程（ｂ）で、エッチングマスク５がパターニングされると、Ｘ線吸収体４の凹部のエッチングマスクはエッチングされにくく、（ｃ）工程でＸ線吸収体４をエッチングするとＸ線吸収体４の凹部に残ったエッチングマスク５はパターンの一部とみなされ、エッチングマスク５が除去された工程（ｄ）では残渣として現れる。本発明のように、吸収体のエッチングの際、異方性の高いエッチングと等方性のエッチングを制御することにより、残存するエッチングマスクの直下のＸ線吸収体部分をサイドからエッチングし（工程（ｄ’））、残渣発生を抑制する（工程（ｅ’））。
【０１２２】
実施例１７．
以下、本発明の一実施例について図を用いて説明する。図１３は、この発明の実施例によるＸ線マスクの製造装置であるエッチング装置の構成の一部を示したものである。図において、２０は超音波振動子、２１ａはウエハ状態でのＸ線マスクである。
【０１２３】
このような構成のエッチング装置でパターニングを行うと、ウエハが振動し、かつパターン面が下向きのため、エッチング残渣が発生した場合でも、残渣が落下しやすいため、最終的なパターン精度が向上する。なお、請求項１１〜１７の対策も併せて行うと残渣発生をさらに抑えることができる。また、他の原因で発生したゴミも除去されやすくなるという特徴もある。なお、超音波はエッチング中およびエッチングの前後にも与えて効率よく残渣を除去する。
【０１２４】
実施例１８．
以下、本発明の他の実施例について図を用いて説明する。図１４は、この発明の実施例によるエッチング装置の構成の一部を示したものである。図において、２１ｂはメンブレン状態でのＸ線マスク、２２はガスバルブである。
【０１２５】
このような構成のエッチング装置を用い、冷却用ガスを間欠的に流せば、メンブレン状態でのマスク、特にメンブレン部分が振動するため残渣が発生してもより落ちやすくなる。そのため、寸法精度の良いパターニングを行うことができる。
【０１２６】
実施例１９．
以下、本発明の一実施例について図を用いて説明する。図１５はこの発明の実施例によるＸ線マスクの製造装置の構成の一部を示したものである。図において、２５はレーザ発振器２３より発せられたレーザ光２４を感知するデテクタである。なお、図中（ａ）はＸ線吸収体のエッチング前の状態、（ｂ）はＸ線吸収体のエッチングが終了した時を示している。なお、レーザ光２４の照射場所はパターン外側に設けられたアライメントマーク等の幅広い抜きパターンがよい。また、レーザ光２４は例えば、６３３ｎｍの波長を有するＨｅ−Ｎｅレーザや７８０ｎｍの半導体レーザ等を用いる。
【０１２７】
このような構成の装置でエッチングを行うと、吸収体のエッチングが完了していない時は、レーザ光２４はＸ線吸収体４に阻まれるため透過せず、デテクタ２５には光は届かない。しかし、吸収体のパターンが形成されるとレーザ光２４がメンブレン２を透過するためデテクタ２５にレーザ光２４は感知される。同じ材質であってもパターン幅によってエッチング速度は変化するため、予めパターン幅とエッチング速度の関係を求めておき、所望のパターンが得られるよう、デテクタ２５に光を感知した後、適切なオーバエッチングを施す。これにより、微細パターンを含む回路パターンを適切にエッチングできる。さらに、スパッタの際の膜厚むら等によるエッチング時間のばらつきが緩和され、寸法精度のよい、Ｘ線マスクを作製できる。
【０１２８】
実施例２０．
以下、本発明の一実施例について図を用いて説明する。図１６はこの発明の実施例によるＸ線マスクの構造を示す断面図である。図において、２６はＡｌＺｎＯｘ膜で、スパッタリングによりメンブレン２の上に約０．１μｍの厚さに成膜した例を示す。
【０１２９】
このように作製されたＸ線マスクでは、ＡｌＺｎＯｘ膜２６は透明で、電気伝導性があるため、ＳｉＣからなるメンブレン２の反射防止膜として機能し、可視光透過率を改善するとともに、帯電防止膜としても機能する。また、ＡｌＺｎＯｘ膜２６の主成分は軽元素のＡｌであるため、従来用いられてきたＩＴＯに比べてＸ線の透過率が高い。例えば、反射防止膜をＩＴＯからＡｌＺｎＯ_３（ＡｌＺｎＯｘのｘ＝３の場合）に変更することにより、約１０〜３０％のＸ線透過率の改善がなされる。また、吸収体にタングステン系の材料を用いた場合、ＡｌＺｎＯｘは吸収体エッチング時のエッチングストッパとしても十分な能力を示した。
【０１３０】
本実施例ではＡｌＺｎＯｘ膜についての例を示したが、ＡｌＺｎＯｘ膜と同様にＳｎＳｂＯｘまたはＳｎＯｘ膜用いても、Ｘ線透過率の向上が実現する。この場合ＡｌＺｎＯｘよりは重元素の構成であるが、導電性のため、帯電防止の効果は有する。
【０１３１】
実施例２１．
以下、本発明の一実施例について図を用いて説明する。図１７はこの発明の実施例によるＸ線マスクの製造工程を示す図である。図において、２７ａは製造工程用のＸ線マスクで、シリコンがバックエッチされた状態にある。２８ａは予め反り計測がなされたシリコンウエハであり、その片面にはメンブレンが成膜されている応力計測用Ｘ線マスクモニタ用ウエハである。これらは同一装置、同一バッチでＷ−Ｔｉ吸収体を成膜し、２７ｂは成膜後のＸ線マスク、２８ｂは成膜後のシリコンウエハを示している。その際、同じ特性のＸ線吸収体膜４が成膜されるように自公転タイプのステージを備えたスパッタ装置を用い、また基板とターゲット間距離が一定になるようにした。成膜後、応力計測用Ｘ線マスクモニタウエハ２８ｂの反りを計測し、アニールを行った。アニール後再び、モニタウエハの反りを計測し、これら計測結果からＸ線吸収体４の応力が０となる最終アニール温度を決定した。ＷーＴｉ吸収体膜ではアニール温度と応力変化が比例するため最終アニール温度の決定は容易である。そして、上記最終アニール温度で工程中のＸ線マスクのアニールを行った。これにより、スパッタ装置のバッチ間の再現性に依存しない。低応力の吸収体が成膜されたＸ線マスクを得ることができる。
【０１３２】
上記実施例では、シリコン基板にサポートリングが接合されていない例について示したが、図１８のＸ線マスクの製造工程を示す図のように、工程中のＸ線マスクでメンブレン２が成膜されたシリコン基板１がサポートリング８に接合されている状態においても、応力計測用Ｘ線マスクモニタウエハを同じスパッタ装置に配置すれば、低応力吸収体を得るためのアニール温度は同様な方法で、決定することができる。なお、図において、２９ａはサポートリングの接合された製造工程用Ｘ線マスク、２９ｂは該Ｘ線マスクにＸ線吸収体が成膜された状態を示す。
【０１３３】
さらに、上記実施例では、低応力吸収体を得るための手法としてアニール工程を用いた例について示したが、図１９のＸ線マスクの製造工程を示す図のように、吸収体膜の応力調整をイオン注入によって行ってもよい。この場合、モニタウエハの反り計測から最終イオンドーズ量を決定し、その値のドーズ量を工程中のＸ線マスクに与えることで０応力の吸収体を得る。
【０１３４】
さらに、上記実施例では、モニタウエハとしてＸ線マスク製造工程用の基板と同一材料であるであるシリコン基板を用いた例について示したが、成膜条件と応力の関係および、シリコン基板と応力の相関関係が明らかな材料であれば、シリコン基板に限定されるものでもない。シリコン基板を用いれば、安価にモニタを実施できるという効果がある。
【０１３５】
実施例２２．
以下、本発明の一実施例について図を用いて説明する。上記実施例２１では、応力計測用Ｘ線マスクモニタウエハとして、シリコンウエハを用いる例について説明したが、より正確な応力モニタリングにはシリコンウエハより高価になるが、製造工程用のＸ線マスクと同様のバックエッチ済みのウエハを用いることが望ましい。図２０はこの発明の実施例によるＸ線マスクの製造工程を示す図である。図において、４２ａは成膜前のバックエッチされたモニタウエハを、４２ｂは成膜後のバックエッチされたモニタウエハを示している。バックエッチされたウエハは通常引っ張り応力により皿状に反っている。この反った状態を基準に応力の変化を計測してやれば、実際のプロセスに近い応力を精度良く計測でき、従って低応力化が図れる。なお、製造用のＸ線マスク基板１は、厚さ２ｍｍ程度のシリコンウエハからなっており、モニタウエハ１’は厚さ０．４ｍｍ程度のシリコンウエハを用いている。ウエハは薄い方が応力を高精度に計測できるため、吸収体成膜やアニールによる応力変化はモニタウエハで感度良く計測できより正確な応力制御が可能となる。
【０１３６】
なお、図２０中に応力制御プロセスとして０応力となるアニール温度を決定することが記載されているが、これは実施例２１と同様である。さらに、実施例２１の図１９のように吸収体膜の応力調整をイオン注入によって行ってもよい。この場合、バックエッチされたモニタウエハの反り計測から最終イオンドーズ量を決定し、その値のドーズ量を工程中のＸ線マスクに与えることで０応力の吸収体を得る。
【０１３７】
実施例２３．
以下、本発明の一実施例について図を用いて説明する。上記実施例２１は、最も簡単な構造のＸ線マスクに対応するもの、あるいはＸ線吸収体のみに注目した低応力化である。しかし、最終的にＸ線吸収体と同一のパターンを形成する膜を備えたＸ線マスクの製造工程に対しては、それらの膜を一括して応力制御する必要がある。図２１はＸ線吸収体と同一のパターンを形成する膜を備えたＸ線マスクの製造工程の一部を示したものである。図中（ａ）は、Ｘ線吸収体を成膜する前の基板の状態を示している。ここではシリコンウエハ１上にメンブレン２と反射防止膜（ＡＲコート）１０のみが成膜されている。図中（ｂ）はアニールする前の所望の膜が基板上に成膜されたＸ線マスクの状態を示している。この段階ではＣｒエッチングストッパ９、酸化珪素からなる平坦化膜５０、Ｗ−Ｔｉ吸収体膜４が成膜されている。
【０１３８】
つぎに、アニール工程について説明する。アニール工程は特願平５ー２３３１８７号で記載のＸ線吸収体の応力制御の原理を利用する。図２２はアニール温度と応力との関係を示す図で、アニール処理中の応力変化を図示したものである。図において、横軸は温度、縦軸は応力または応力と相関する物理量（例えば、反りの高さや曲率などの測定値）を表わし、＋方向は引張り応力、ー方向は圧縮応力である。また、図中、Ａは室温での成膜後のアニール開始前のＸ線マスクの応力状態、Ｂはアニール効果発現点、Ｃはアニール停止点、Ｄは室温でのアニール完了時点をそれぞれ示している。
【０１３９】
図２１中（ｂ）で示したＸ線マスクを加熱すると、基板材料であるシリコンと吸収体等の膜の熱膨張率の差により、応力は、図２２中Ａ→Ｂと変化する。加熱温度をさらに上げると、点Ｂで、応力は直線Ａ−Ｂから離れ出す。これは、結晶構造の変化や、吸収体中に取り込まれたガスの脱離などによりアニール効果が発現されるためである。
【０１４０】
ところで、目標とする状態は点Ｄである。この点を求めるためには、直線Ａ−Ｂが求められた時点で、直線Ａ−Ｂに平行で、かつ応力または応力と相関する物理量が零となる室温でのアニール完了点Ｄを通る直線Ｄ−Ｄ’を予め求めておくことにより、点Ｂを過ぎた後も応力をモニタし、点Ｄを通り、直線Ａ−Ｂに平行な直線Ｄ−Ｄ’と交差する点Ｃに達した時点で、アニールを停止（加熱停止）し、基板を室温まで冷却することにより、点Ｄの状態が得られる。即ち、点Ｄでは、図２１中（ａ）と同じ応力状態である。
【０１４１】
従って、上記実施例によれば、Ｘ線吸収体と同じパターンが形成される所望の膜全てを積層したＸ線マスクをアニール工程中に応力あるいは応力に相関する物理量を計測しモニタすることにより、アニール完了時点を決定できるため、再現性よくパタニングされる層（吸収体やエッチングストッパ）の応力の総和を低減することができる。
【０１４２】
実施例２４．
以下、本発明の一実施例について図を用いて説明する。実施例２３と同様にＸ線吸収体と同じパターンが形成される所定の層を複数積層したＸ線マスクのアニール処理による低応力化の別の実施例である。図２３はアニール温度と応力との関係を示す図である。図において、横軸はアニール温度、縦軸は応力または応力と相関する物理量（例えば、反りの高さや曲率などの測定値）を表わし、＋方向は引張り応力、ー方向は圧縮応力である。図では、成膜後と比較して、アニール処理の温度とその温度での応力値との関係を示している。あるサンプル１〜３において、予め予想されるアニール温度θよりも低い２点の温度θＭ１、θＭ２でアニール処理を行い、その度に応力を計測する。この２点の応力計測結果を結ぶ直線と応力ゼロの線との交点から、サンプルあるいはバッチごとに最終アニール温度θａが決定される。ここでは、サンプル１〜３に対してθａ１、θａ２、θａ３を決定し、その決定された温度でアニールを行うことにより、低応力の積層膜（吸収体を含む）が得られる。
【０１４３】
なお、上記実施例ではアニール温度θよりも低い温度をθＭ１、θＭ２の２点としたが、少なくとも２点であれば３点以上であってもよい。測定点が多いと決定温度の精度が向上することは言うまでもない。
【０１４４】
実施例２５．
以下、本発明の一実施例について図を用いて説明する。図２４はこの発明の実施例によるＸ線マスクの製造工程を示す図である。図において、４３ａは製造工程用のＸ線マスクでシリコンがバックエッチされ、ＡＲコート１０とメンブレン２が成膜されている。４４ａは成膜前のバックエッチされたモニタウエハを、４４ｂは成膜後のバックエッチされたモニタウエハを示している。成膜前のモニタウエハ４４ａでは、ＡＲコート１０の成膜は省略した。次に、メンブレン２の上に、エッチングストッパ９、平坦化膜５０、Ｘ線吸収体４を製造工程用Ｘ線マスク４３ａと同じ条件で成膜し、多層に成膜された製造工程用Ｘ線マスク４３ｂと同時にモニタウエハ４４ｂを得る。ここで、モニタウエハ４４ｂを用いて最終アニール温度を確定し、Ｘ線マスク基板もその温度でアニールを行う。なお、モニタウエハにより最終アニール温度を求める手順は、上記実施例２３や２４の手法を用いればよい。
【０１４５】
なお、上記実施例では、多数の膜が成膜された後のモニタウエハを用いて最終アニール温度を確定し、それに基づいて工程中のＸ線マスク基板をアニール処理したが、最終アニール温度でのアニールだけでなく、モニタウエハを用いた実施例２３や２４の中途の温度、例えば実施例２４のθＭ１、θＭ２での処理もモニタウエハと同じように行ってもよい。
【０１４６】
実施例２６．
以下、本発明の一実施例について図を用いて説明する。図２５はこの発明によるＸ線マスクの製造方法を示す工程図である。図において、３０はＸ線吸収体と選択比の高い、吸収体エッチング用中間層で、例えば、ＣｒやＡｌ_２Ｏ_３である。工程（ａ）では、予めバックエッチ済みのＸ線透過性基板（例えばシリコン基板）１にエッチングストッパ９、第１の成膜工程によるＸ線吸収体４ａ、レジスト膜６を成膜する。その際、選択比の高い中間層３０をレジスト膜６とＸ線吸収体４ａの間に挿入する。工程（ｂ）では、第１のパターン形成を行うためのレジスト膜６を形成し、それをエッチングマスクとして中間層３０をエッチングし、次いで、第１のパターン形成を行った中間層をエッチングマスクとして第１のＸ線吸収体膜４ａをエッチングすることにより、膜厚の厚いかぶり露光防止用Ｘ線吸収体パターンが形成される。工程（ｃ）では、その上に第２のＸ線吸収体膜４ｂを成膜し、レジスト６を再塗布する。第１のパターン形成工程と同様にＸ線吸収体と選択比の高い中間層３０をレジスト膜６とＸ線吸収体４ｂの間に挿入する。最終工程（ｄ）では、第２のパターン形成を行うためレジスト膜をパターン形成し、それをエッチングマスクとして中間層３０をエッチングし、次いで第２のパターン形成を行った中間層３０をエッチングマスクとして第２のＸ線吸収体膜４ｂをエッチングすることにより、Ｘ線吸収体回路パターン７を得る。
【０１４７】
実施例２７．
以下、本発明の一実施例について図を用いて説明する。図２６はこの発明によるＸ線マスクの製造方法を示す工程図である。図中工程（ａ）において、第１の成膜工程によるＸ線吸収体４ａを成膜後、その上にレジスト膜６塗布する。工程（ｂ）で、第１の成膜工程によるＸ線吸収体４ａのパターン形成を行う際、所定の厚みまでエッチングする。例えば、１μｍのＸ線吸収体を成膜後、０．５μｍまでエッチングする。次いで、工程（ｃ）で、レジスト６を再塗布し、回路パターン形成を行う。最終工程（ｄ）で、パターン形成したレジスト膜６をエッチングマスクとしてエッチングすることにより、所望のＸ線吸収体回路パターン７を得る。
【０１４８】
このように、予めかぶり露光防止用Ｘ線吸収体を成膜する際、Ｘ線吸収体をある厚みまでエッチングした後、レジスト再塗布、転写、エッチングするＸ線マスクの製造方法においては、回路パターン形成の前にかぶり露光防止用Ｘ線吸収体が形成されているため、このかぶり露光防止用Ｘ線吸収体膜の応力が回路パターンの位置精度に影響することはなく、それゆえ、精度の高い回路パターンが形成できるとともにＸ線吸収体成膜工程が１回ですむ。
【０１４９】
実施例２８．
以下、本発明の一実施例について図を用いて説明する。図２７はこの発明によるＸ線マスクの製造方法を示す工程図で、実施例２６の図２５においてＸ線かぶり露光防止用Ｘ線吸収体部に順テーパを設ける例である。図において、工程（ａ）は予めバックエッチ済みのＸ線透過性基板１にエッチングストッパ９、第１の成膜工程によるＸ線吸収体４ａ、レジスト膜６を成膜する。その際、Ｘ線吸収体４ａと選択比の高い中間層３０をレジスト膜６とＸ線吸収体４ａの間に挿入する。工程（ｂ）では、第１のパターン形成を行うためのレジスト膜６を形成し、それをエッチングマスクとして中間層３０をエッチングし、次いで、第１のパターン形成を行った中間層をエッチングマスクとして第１のＸ線吸収体膜４ａをエッチングする。この際、Ｘ線吸収体の側壁を順テーパをつける条件、例えば、エッチング条件を制御し、比較的等方性のエッチングを施せばよい、でエッチングし、約６０〜７０゜程度の角度を持たせることが望ましい。これにより、膜厚の厚いかぶり露光防止用Ｘ線吸収体パターンが形成される。工程（ｃ）では、その上に第２のＸ線吸収体膜４ｂを成膜し、レジスト６を再塗布する。第１のパターン形成工程と同様にＸ線吸収体と選択比の高い中間層３０をレジスト膜６とＸ線吸収体４ｂの間に挿入する。最終工程（ｄ）では、第２のパターン形成を行うためレジスト膜をパターン形成する。その際、周囲のＸ線吸収体は順テーパを有するので、レジスト塗布時に均一なレジスト膜を成膜でき、その結果精度の高い回路パターンが形成できる。次いで、中間層３０をエッチングし、次いで第２のパターン形成を行った中間層３０をエッチングマスクとして第２のＸ線吸収体膜４ｂをエッチングすることにより、Ｘ線吸収体回路パターン７を得る。
【０１５０】
実施例２９．
以下、本発明の一実施例について図を用いて説明する。図２８はこの発明によるＸ線マスクの製造方法を示す工程図である。図において、３１はかぶり露光防止板で、シリコン基板１に取付られている。このような構成にすることで、簡単な手法でかぶり露光防止が可能になり、Ｘ線マスク作成時間、Ｘ線マスク作成コストを削減できる。また、サポートリング下面を越えないように張り付けることで、Ｘ線マスクをステッパーに装着することが容易になる。さらに張り付ける作業は回路パターン、アライメントパターン精度に影響を及ぼさないため、精度のよい回路パターン、アライメントパターンが形成可能になる。
【０１５１】
実施例３０．
以下、本発明の一実施例について図を用いて説明する。図２９はこの発明によるＸ線マスクの製造方法を示す工程図である。図において、３２は耐アルカリ性レジスト、３３はヒータ、３４はＫＯＨ溶液である。図において、シリコン基板（ここでは（１００）面を使用）のＫＯＨを含む溶液に対する面異方性エッチングによって、かぶり露光防止板を作成することにより、開口部の四隅の角度が直角なかぶり露光防止板が得られる。これは、シリコン基板がＫＯＨを含む溶液に対して、（１１１）面、（１１０）面、（１００）面の順で溶解しにくい特性を利用するもので、かぶり露光防止板開口部の四隅を溶解しやすい面に、開口部の各辺の中心を溶解しにくい方向にあわせることにより、四隅の角度が直角で丸みのないかぶり露光防止板を作製できる。
【０１５２】
実施例３１．
以下、本発明の別の実施例について図を用いて説明する。図３０はこの発明によるＸ線マスクの製造方法を示す工程図である。図において、３５はＳｉＣである。工程（ａ）で、シリコンウエハ１の両面にＳｉＣ３５をＣＶＤ法により成膜する。次いで、工程（ｂ）では、片面のＳｉＣの中央部をエッチングによって除去する。これは光転写法とドライエッチング法を用いた。次いで、工程（ｃ）では上記基板１をヒータ３３により８０〜１００℃に加熱された飽和ＫＯＨ溶液３４に浸漬することにより、ウインドウ領域のエッチングを行なう。例えば１００μｍの厚さのシリコンであれば、約３０分でエッチングが完了する。上記プロセスによりミクロンオーダーで正確なサイズのかぶり露光防止板を得ることができる。
【０１５３】
実施例３２．
以下、本発明の一実施例について図を用いて説明する。図３１はこの発明によるＸ線マスクの製造方法を示す工程図である。図において、３６はかぶり露光防止板の開口部の大きさと同じ断面を持つ角柱、３７は矩形のＸ線遮蔽板である。工程（ａ）では、例えば厚さ２００μｍのガラス製のＸ線遮蔽板３７を４枚、角柱３６に沿わせて組み合せ、接合する。次いで、工程（ｂ）で、該角柱３６を抜く。最後に工程（ｃ）で、Ｘ線マスクのサポートリング８の内側に取り付ける。このように、シリコンウエハ１とサポートリング８に接して取り付けるため、ガラス製のＸ線遮蔽板３７はシリコンウエハ１とサポートリング８と同等の表面粗さおよび平面度が必要となる。以上のように、簡便でしかも高精度で、開口部の隅が完全に直角のかぶり露光防止板を得ることができる。
【０１５４】
【発明の効果】
以上のように、この発明の１の局面に従ったＸ線マスクの製造方法によれば、エッチングマスクの厚さがＸ線吸収体の厚さと必要とされる精度により規定された最低限の厚さの薄いものであるため、エッチングマスクのパターンを形成するエッチングの際、エッチングが異方性、等方性に依らず、寸法精度は維持できる。その結果Ｘ線吸収体のエッチングの際の寸法精度を維持することができ、高精度のＸ線マスクを歩留りよく提供できる。
【０１５６】
また、上記１の局面に従ったＸ線マスクの製造方法によれば、等方的にエッチングされたエッチングマスクを用いて、Ｘ線吸収体のエッチングを行なうので、吸収体の側壁が斜めにエッチングされる。そのため、このＸ線マスクを用いると、Ｘ線位相シフト効果によるパターンエッジ部の回折現象により、微細パターンまで転写可能となる。
【０１５７】
また、以上のようにこの発明の他の局面に従ったＸ線マスクによれば、白金やその化合物は、タングステンを含むＸ線吸収体とのエッチングの際エッチングの選択比が大きいため、Ｘ線吸収体のエッチングが容易に行なわれる。また、クロムの窒化物やクロムの窒化酸化物はタングステンを含むＸ線吸収体との選択比が大きいため、白金やその化合物と同様にＸ線吸収体のパターニングの際のエッチングマスクやエッチングストッパとして優れており、高精度のＸ線マスクを歩留りよく提供できる。
【０１６１】
また、以上のようにこの発明の別の局面に従ったＸ線マスクによれば、パターンが形成されたＸ線吸収体の上に２次電子抑制層を備えたので、完成したＸ線マスクを用いてパターンを転写する際にＸ線による２次電子の励起を抑制することができ、高精度のパターン転写が可能となる。
【０１６２】
また、以上のように上記別の局面に従ったＸ線マスクによれば、２次電子抑制層として炭素を主成分とする層を用いたので、Ｘ線による２次電子の励起抑制が効率的に行なわれ、高精度のパターン転写が可能となる。
【０１６３】
また、以上のように上記別の局面に従ったＸ線マスクの製造方法によれば、炭素を主成分とする２次電子抑制層の形成方法として、Ｘ線マスクパターンのエッチングが終わった後、エッチングガスの成分を変えることで、炭素を含む膜を成膜したので、簡便に２次電子抑制層が形成でき、高精度のパターン転写が可能となる。
【０１６６】
また、以上のようにこの発明のその他の局面に従ったＸ線マスクによれば、Ｘ線吸収体とエッチングマスクまたはＸ線吸収体とエッチングストッパの間に拡散抑制層を備えたので、拡散層部で発生し易いエッチング残渣の発生を抑制でき、最終的な転写精度の低下を防止することができる。
【０１６７】
また、以上のように上記その他の局面に従ったＸ線マスクでは、Ｘ線吸収体上にエッチングマスクを形成する工程の前にＸ線吸収体をアニールする工程を配置したので、Ｘ線吸収体とエッチングマスクとの間に熱による拡散層の形成が防止され、且つＸ線吸収体の表面に薄い酸化層が形成され、残渣発生を抑制でき、最終的な転写精度の低下を防止することができる。
【０１６８】
また、以上のように上記その他の局面に従ったＸ線マスクによれば、Ｘ線吸収体とエッチングストッパの間、あるいはＸ線吸収体とエッチングマスクの間にＸ線吸収体と同じ条件でエッチングされる層を備えたので、Ｘ線吸収体とエッチングストッパ、あるいはＸ線吸収体とエッチングマスクの混合が抑えられるので、残渣発生を抑制でき、最終的な転写精度の低下を防止することができる。
【０１６９】
また、以上のように上記その他の局面に従ったＸ線マスクによれば、タングステンまたはタングステン化合物からなるＸ線吸収体と同じ条件でエッチングされる層として、シリコンを含有する層を用いたので、簡便な手法で、層を形成することができ、残渣発生を抑制できる。
【０１７０】
また、以上のようにこの発明のまた別の局面に従ったＸ線マスクによれば、Ｘ線吸収体の表面粗さを制御したので、従来のように、凹部のあるエッチングマスク材のエッチングが困難なため凹部に溜っていた残渣がなくなり、最終的な転写精度の低下を防止することができる。
【０１７１】
また、以上のようにこの発明のもう１つの局面に従ったＸ線マスクの製造方法によれば、Ｘ線吸収体のエッチングを行なう工程において、異方性と等方性のエッチングを制御して行なうので、異方性の強いエッチングの場合形成されやすい、針状の残渣を除去しやすくなり、高精度名Ｘ線マスクを形成でき、最終的な転写精度の低下を防止することができる。
【０１７２】
また、以上のようにこの発明のさらに他の局面に従ったＸ線マスクの製造方法によれば、エッチングの際に被エッチング面を下向きにし、Ｘ線マスクを震動させながらエッチングしたので、表面に発生した残渣を下に落して排除し易くなり、最終的な転写精度の低下を防止することができる。
【０１７３】
また、以上のようにこの発明のさらに別の局面に従ったＸ線マスクの製造方法によれば、Ｘ線マスクの透過光の変化でエッチングを終了させたので、ロットが異なり膜厚の違うサンプルでも適切なエッチング形状を得ることができ、ロット間のばらつきの少ない均一なエッチングを行なうことができ、高精度のＸ線マスクを提供することができる。
【図面の簡単な説明】
【図１】この発明の実施例１、４、５、１１、１２、１５、１６によるＸ線マスクの構造を示す断面図である。
【図２】この発明の実施例１によるエッチングマスクの膜厚とＸ線吸収体パターン形成の関係を示す原理図である。
【図３】この発明の実施例２によるＸ線マスクの構造を示す断面図である。
【図４】この発明の実施例３によるＸ線マスクの製造方法を示す工程図である。
【図５】この発明の実施例６によるＸ線マスクの製造装置の１つであるエッチング装置の全体構成図である。
【図６】この発明の実施例６によるＸ線マスクの製造装置の構成の一部を示したものである。
【図７】この発明の実施例７によるＸ線マスクの製造装置の構成の一部を示したものである。
【図８】この発明の実施例８によるＸ線マスクの製造装置の構成の一部を示し、図中（ａ）はバックエッチ済のＸ線マスクを搭載した場合、（ｂ）はウエハ状態のＸ線マスクを搭載した場合を示す。
【図９】この発明の実施例８によるＸ線マスクの製造装置の構成の一部を示したものである。
【図１０】この発明の実施例９、１０によるＸ線マスクの製造方法を示す工程図である。
【図１１】この発明の実施例１３、１４によるＸ線マスクの構造を示す断面図である。
【図１２】この発明の実施例１６によるＸ線マスクに発生した残渣の除去工程を示す図である。
【図１３】この発明の実施例１７によるＸ線マスクの製造装置の構成の一部を示したものである。
【図１４】この発明の実施例１８によるＸ線マスクの製造装置の構成の一部を示したものである。
【図１５】この発明の実施例１９によるＸ線マスクの製造装置の構成の一部を示したものである。図中（ａ）はＸ線マスクの吸収体エッチング前の状態を、（ｂ）は吸収体のエッチングが終了した時点を示している。
【図１６】この発明の実施例２０によるＸ線マスクの構造を示す断面図である。
【図１７】この発明の実施例２１によるＸ線マスク製造工程を示す工程図である。
【図１８】この発明の実施例２１によるＸ線マスク製造工程を示す工程図である。
【図１９】この発明の実施例２１によるＸ線マスク製造工程を示す工程図である。
【図２０】この発明の実施例２２によるＸ線マスク製造方法を示す工程図である。
【図２１】この発明の実施例２３によるＸ線マスク製造方法を示す工程図である。
【図２２】この発明の実施例２３によるＸ線マスクのアニール温度決定方法を説明する図である。
【図２３】この発明の実施例２４によるＸ線マスクのアニール温度決定方法を説明する図である。
【図２４】この発明の実施例２５によるＸ線マスク製造方法を示す工程図である。
【図２５】この発明の実施例２６によるＸ線マスク製造方法を示す工程図である。
【図２６】この発明の実施例２７によるＸ線マスク製造方法を示す工程図である。
【図２７】この発明の実施例２８によるＸ線マスク製造方法を示す工程図である。
【図２８】この発明の実施例２９によるＸ線マスクを示す断面図である。
【図２９】この発明の実施例３０によるＸ線マスク用かぶり露光防止板の製造方法を示す工程図である。
【図３０】この発明の実施例３１によるＸ線マスク用かぶり露光防止板の製造方法を示す工程図である。
【図３１】この発明の実施例３２に係わるＸ線マスク製造方法を示す工程図である。
【図３２】従来のＸ線マスクの構造を示す断面図である。
【図３３】従来のＸ線マスクの製造方法を示す工程図である。
【図３４】Ｘ線マスクを用いてパターンを転写する原理図である。
【図３５】従来のかぶり露光防止機能を有するＸ線マスクの製造工程を示す断面図である。
【図３６】従来のＸ線マスクの工程を示す別の工程図である。
【図３７】従来のＸ線マスクの構造を示す別の断面図である。
【符号の説明】
１ シリコン基板、 ２ メンブレン（ＳｉＣ膜）、 ３ 保護膜（ＩＴＯ膜）、 ４ Ｘ線吸収体膜、 ４ａ 第１の成膜工程により形成されたＸ線吸収体膜、
４ｂ 第２の成膜工程により形成されたＸ線吸収体膜、
５ エッチングマスク（Ｃｒ膜）、 ５ａ エッチングマスク（ａ）、
５ｂ エッチングマスク（ｂ）、 ６ レジスト膜、 ６’ レジストパターン、
７ 回路パターン、 ８ サポートリング、 ９ エッチングストッパ、
１０ ＡＲコート、 １１ パッキン、 １２ 冷却ステージ、
１３ ウエハ押え、 １４ 冷却用ガス穴、 １５ 高分子膜、
１６ 冷却台、 １７ スペーサ、 １８ 炭素を含む膜、
１９ 吸収体と同じ条件でエッチングされる薄膜、 ２０ 超音波振動子、
２１ａ ウエハ状態でのＸ線マスク、 ２１ｂ メンブレン状態でのＸ線マスク、
２２ ガスバルブ、 ２３ レーザ発振器、 ２４ レーザ光、
２５ デテクタ、 ２６ ＡｌＺｎＯｘ膜、 ２７ａ 製造工程用のＸ線マスク、
２７ｂ Ｘ線吸収体膜が形成された製造工程用のＸ線マスク、
２８ａ 応力計測用Ｘ線マスクモニタウエハ、
２８ｂ Ｘ線吸収体膜が形成された応力計測用Ｘ線マスクモニタウエハ、
２９ａ サポートリング付の製造中のＸ線マスク、
２９ｂ Ｘ線吸収体膜が形成されたサポートリング付の製造中のＸ線マスク、
３０ 吸収体エッチング用中間層、 ３１ かぶり露光防止板、
３２ 耐アルカリレジスト、 ３３ ヒータ、 ３４ ＫＯＨ溶液、
３５ ＳｉＣ、 ３６ 角柱、 ３７ Ｘ線遮蔽板、 ３８ Ｘ線マスク、
３８ａ Ｘ線マスク上のパターン、 ３８ｂ Ｘ線マスク上のＸ線透過領域、
３９ シリコン基板、 ４０ 半導体パターン、 ４１ Ｘ線
４２ａ 応力計測用Ｘ線マスクモニタウエハ（バックエッチされたウエハ）、
４２ｂ Ｘ線吸収体膜が形成された応力計測用Ｘ線マスクモニタウエハ、
４３ａ 製造工程用Ｘ線マスク（バックエッチされたウエハ）
４３ｂ 所望の膜が多層に形成された製造工程用Ｘ線マスク（バックエッチされたウエハ）
４４ａ 応力計測用Ｘ線マスクモニタウエハ（バックエッチされたウエハ）、
４４ｂ 所望の膜が多層に形成された応力計測用Ｘ線マスクモニタウエハ、[0001]
[Industrial applications]
The present invention relates to an X-ray mask used for X-ray lithography and a method of manufacturing the same. To the law Related.
[0002]
[Prior art]
FIG. 32 shows a schematic structure of a conventional X-ray mask disclosed in Japanese Patent Laid-Open No. Hei 5-217762. In the figure, 1 is a silicon (Si) substrate having a thickness of about 2 mm, 2 is a membrane (X-ray transmitting material) having a thickness of about 2 μm formed on a silicon substrate, and is usually a light element ceramic having a good X-ray transmittance such as SiC. Consists of Reference numeral 3 denotes a protective film made of indium tin oxide (ITO) for preventing the membrane from reflecting visible light or being charged by charged particles. Reference numeral 4 denotes an X-ray absorber made of a tungsten (W) film (W-Ti) containing 1 to 2% of titanium (Ti), on which a desired semiconductor circuit pattern 7 is formed. Reference numeral 5 denotes an etching mask for patterning the X-ray absorber, which is made of chromium (Cr).
[0003]
Next, the manufacturing process of the X-ray mask will be described with reference to FIG. In the step (a), a SiC film 2 is formed on the upper surface of the silicon substrate 1, and in the step (b), a central portion of the silicon substrate is dissolved and removed with a chemical such as hydrofluoric nitric acid to form a self-supporting film (membrane) 2 of SiC. . This step is called a back etch. Next, in step (c), an ITO film 3 having an etching stopper and anti-reflection function, a W-Ti film 4 as an X-ray absorber, a Cr film 5 as an etching mask, and a resist film 6 are sequentially sputtered or spin-coated. And a semiconductor pattern is drawn by an electron beam (not shown). In the step (d), the resist is developed to form a resist pattern 6 '. In step (e), Cl ₂ / O ₂ The Cr film is etched using a mixed gas of ₆ / CHF ₃ Using a gas mixture, the silicon substrate is cooled from the bottom with low-temperature helium (He) or the like to about −50 ° C., and a circuit pattern 7 of W—Ti is formed by low-temperature etching. Since the ITO film on the bottom surface has high etching selectivity with W-Ti, it is stable even if the etching time is lengthened, and a uniform vertical pattern can be formed in the mask surface.
[0004]
FIG. 34 shows a principle diagram of transferring a pattern onto a silicon wafer using a completed X-ray mask. In this example, an X-ray mask 38 is placed in parallel with a silicon wafer 39 coated with an exposure material (resist) in parallel (gap = 10 to 50 μm) and irradiated with X-rays 41 from a synchrotron (SR) radiation source or the like. is there. The fine semiconductor pattern 38a on the mask can be transferred onto the silicon wafer 39. In the figure, reference numeral 38b denotes a region (window) of the fine semiconductor pattern 38a on the mask, and reference numeral 40 denotes a pattern transferred onto the silicon wafer 39.
[0005]
Further, since the size (window size) of the X-ray transmission area of the X-ray transmission layer (membrane) is generally larger than the circuit pattern, exposure is repeatedly performed on a process wafer using this X-ray mask. In order to form as many chip patterns as possible, a part of an adjacent chip is subjected to multiple exposures (up to four times) along the sides of a rectangular window during X-ray exposure. Further, if an attempt is made to avoid multiple exposures with an interval between adjacent chips, exposure can be performed only for each window size of the X-ray mask, and the number of chips that can be formed on a process wafer is reduced. . This problem related to multiple exposure is called fog exposure. In order to avoid this fogging exposure, it is conceivable to increase the thickness of the X-ray absorber to such an extent that a sufficient contrast can be obtained even in quadruple exposure. However, it is not always preferable that the absorber be thicker, and it is difficult to form a pattern of the absorber having a high aspect ratio by etching.
[0006]
FIG. 35 is a process chart showing a conventional method of manufacturing an X-ray mask used to avoid this problem. In the drawing, reference numeral 8 denotes a support ring, and reference numeral 10 denotes an AR coat, which also serves as an etching stopper. 4a is an X-ray absorber film formed by the first film forming step, and 4b is an X-ray absorber film formed by the second film forming step. The steps will be described according to (a) to (d). First, in the first film forming step (a), an AR coat 10, also serving as an etching stopper, a first X-ray absorber film 4a, and a resist film 6 are formed on the X-ray transmitting layer 2 which has been back-etched in advance. . Next, the resist film 6 is patterned to form a first pattern (b), and the first X-ray absorber film 4a is etched using the resist film 6 as an etching mask. In the next step (c), a second X-ray absorber film 4b is formed on the first X-ray absorber film 4a. Finally, in step (d), after forming a circuit pattern of the recoated resist film 6, the second X-ray absorber 4b is etched by using the circuit pattern as an etching mask to form an X-ray absorber circuit pattern. In this manner, the fog exposure preventing function is formed by increasing the thickness of the X-ray absorber film for preventing fog exposure around the circuit pattern by increasing the thickness of the X-ray absorber film having the circuit pattern. I was
[0007]
[Problems to be solved by the invention]
In the conventional mask as described above, the thickness ratio between the absorber and the etching mask (absorber thickness / etching mask) is smaller than the selectivity at the time of etching (etching rate of the absorber / etching rate of the etching mask). Since this is set and the general etching selectivity is about 10 to 15, the film thickness ratio is usually 10 or less (the etching mask is 10% or more of the thickness of the absorber). When the etching mask is thick as described above, the dimensional accuracy decreases when forming the pattern of the etching mask with the resist, and as a result, the pattern formation of the X-ray absorber must be performed using the etching mask with low accuracy. However, there is a problem that the dimensional accuracy is deteriorated.
[0008]
Conventionally, when the absorber is etched, the etching mask is usually subjected to anisotropic etching which is almost perpendicular to the etching mask. However, when the X-ray absorber is etched in this state, the shape of the X-ray absorber becomes a mask shape. And it was difficult to control the angle of the side wall.
[0009]
Conventionally, chromium, aluminum oxide, and the like are used as an etching mask for an X-ray absorber containing tungsten. Therefore, in these methods, an etching selectivity is insufficient and an appropriate etching shape may not be obtained. There was a point.
[0010]
Also, during etching, the wafer and the stage were mechanically pressed against each other, but this is because the adhesion between the wafer and the stage is not perfect, and the gas for cooling used during low-temperature etching passes through a minute gap. Leaks, lowering the cooling efficiency. The pattern accuracy of the etching has a temperature dependence, and the variation in the cooling temperature is directly reflected on the accuracy, so that there is a problem that the final pattern accuracy is reduced. Even if this gas leakage countermeasure becomes possible, the X-ray mask may be etched in a wafer state during etching, may be performed in a membrane state, or the thickness of the wafer may be different at that time. Since various states are possible, such as when the support ring is bonded to the wafer, it is impossible to etch X-ray masks of various shapes with a single etching device while securing the adhesion between the wafer and the stage. Met.
[0011]
In addition, when performing transfer using a completed mask, if metal is exposed on the surface of the mask, secondary electrons such as photoelectrons and Auger electrons from the absorber hit the resist on the wafer, and as a result, the resist is exposed to these secondary electrons. There is a problem that the pattern is deteriorated by exposure to electrons.
[0012]
Further, if the object to be etched is not sufficiently removed during etching, an etching residue is generated. This residue has an adverse effect on the subsequent film forming and pattern forming steps, and ultimately affects the transfer accuracy. Although there are many causes of generation of residues, there are cases where the selectivity between the X-ray absorber and the etching mask disposed thereon and the X-ray absorber and the etching stopper disposed thereunder is large, When performing anisotropic etching to make the shape after etching as vertical as possible to improve pattern accuracy, removal of the etching mask tends to be insufficient and the etching mask material tends to remain. If the etching material remains, a residue of the X-ray absorber is generated when the X-ray absorber is etched. Further, when the X-ray absorber is not sufficiently etched and the X-ray absorber remains, there is a problem that a residue of the etching stopper is generated when the etching stopper disposed thereunder is etched.
[0013]
In addition, if the etching mask is formed after the absorber is formed as in the conventional case, and then annealing is performed, a diffusion layer is formed at the interface between the absorber and the etching mask. Therefore, the diffusion layer is removed by etching. And there is a problem that the residue of the absorber is easily generated.
[0014]
Further, conventionally, there is a problem that the etching mask in the concave portion of the absorber is difficult to be etched, so that the material of the etching mask is likely to remain, and as a result, residues of the absorber are likely to be generated during the etching.
[0015]
Conventionally, when etching the X-ray absorber, the end of the etching is not sufficiently controlled, for example, is controlled by the etching time, resulting in insufficient etching or uneven etching between lots. There was a problem that occurred.
[0016]
Further, in the conventional X-ray mask, since the SiC film is used as the membrane, the transmittance of the alignment light is low and the antireflection film is required. In the conventional example, by using an indium tin oxide (ITO) film as an anti-reflection film, it has succeeded in having both an etching stopper and an antistatic function. However, a film having such a function is not limited to ITO, and it has been desired to have a range of choices according to the absorber material and the membrane material. In addition, ITO has a problem that the atomic weight of indium and tin is large, and the absorption of X-rays is increased.
[0017]
Further, in order to improve the pattern position accuracy of the X-ray mask, it is essential to reduce the stress of the X-ray absorber (less than 10 MPa). However, since the reproducibility of the film-forming process is insufficient, when the film of the absorber is formed according to a predetermined process, the stress varies within a range of, for example, ± 50 MPa. As a countermeasure, it is conceivable to measure the stress of the absorber during the X-ray mask process. However, only those suitable for stress measurement can be used, and restricted ones cannot be used as X-ray masks. On the other hand, stress measurement is usually performed based on the warpage of a silicon wafer used as a substrate for an X-ray mask membrane, so that the form is different from that of an actually used X-ray mask, and accurate stress measurement and control are difficult.
[0018]
Further, there are the following problems in stress measurement. FIG. 36 shows the manufacturing process of the simplest X-ray mask, and FIG. 37 shows the structure of the X-ray mask in which a desired film is stacked above the X-ray absorber. In the figure, 1 is a silicon substrate, 2 is a membrane made of SiC, 4 is an X-ray absorber, 6 is a resist, 8 is a support ring, 9 is an etching stopper made of Cr, and 10 is SiO ₂ An anti-reflection film (AR coat) made of ₂ Is a flattening film composed of The flattening film 50 is necessary to make the crystal structure of the W—Ti film 4 as an X-ray absorber formed on this film amorphous. In FIG. 37, these films are formed in the order shown in the figure, an electron beam resist (not shown) is applied on these stacked films, and a resist pattern formed by electron beam lithography is used as a mask. The flattening film 50 is etched simultaneously with the W-Ti X-ray absorber 4 to form a pattern. Further, after etching and patterning up to the etching stopper 9, the resist is finally removed to complete the X-ray mask on which the pattern is formed.
[0019]
In the case of a simple structure as shown in FIG. 36, only the X-ray absorber is stress-controlled, and if low stress can be realized, pattern position accuracy can be ensured. However, if the structure is laminated as shown in FIG. 37, even if the stress is controlled only for the X-ray absorber, a film having the same pattern as the X-ray absorber, here, the etching stopper 9 made of Cr and the SiO 2 ₂ There is a problem that the stress control is not performed on the flattening film 50 made of, and the pattern position accuracy is reduced due to the remaining stress.
[0020]
Further, in the conventional X-ray mask manufacturing process, a single-layer etching mask for etching the X-ray absorber in the first film forming process and the second film forming process is used in order to exhibit the fog exposure preventing function. A resist was used. However, when the etching resistance ratio between the resist to be used and the X-ray absorber film is not sufficient, to form a circuit pattern of a thick X-ray absorber film, it is necessary to form a pattern of a thick resist film corresponding thereto. In addition, it is difficult to form a resist pattern with high accuracy by using an electron beam lithography or an excimer stepper, which is generally used as a method of forming a resist film pattern.
[0021]
Further, in the conventional X-ray mask manufacturing process, the X-ray absorber was formed in the first film forming process and the second film forming process, respectively. However, there is a problem that both cost and cost are required, and reduction of these has been an issue.
[0022]
Further, in the conventional X-ray mask manufacturing process, since the angle of the side wall of the X-ray absorber formed in the first pattern formation process is almost vertical and steep, a resist film is uniformly formed on the shape. It is difficult to form a film, which hinders high precision in pattern formation.
[0023]
In addition, in the case of a conventional X-ray mask, if a mechanism for preventing fog exposure is to be provided on the X-ray mask, the steps for its production, namely film formation, resist coating, resist pattern formation, etching And the like, and are contrary to the reduction of the manufacturing time and cost of the X-ray mask.
[0024]
Furthermore, when manufacturing a dedicated fog exposure prevention plate, the four corners of a rectangular window are ideally right angles, that is, it was difficult to manufacture a fog exposure prevention plate having no rounded corners, so that the transfer pattern The accuracy of the corner was low.
[0025]
The present invention has been made to solve such a problem, and an X-ray mask capable of accurately producing an absorber pattern of the X-ray mask. and An object of the present invention is to provide a method for manufacturing an X-ray mask.
[0026]
Further, an X-ray mask capable of preventing the generation of a residue upon patterning, producing an X-ray mask excellent in dimensional accuracy and positional accuracy, and using the X-ray mask to obtain a high-accuracy resist pattern by X-ray transfer is provided. It is an object of the present invention to provide a method for manufacturing a line mask.
[0028]
It is another object of the present invention to provide an X-ray mask having an antireflection film that absorbs less X-rays.
[0029]
It is another object of the present invention to provide a method of manufacturing an X-ray mask having means for knowing the stress of an absorber on an X-ray mask during a process and reducing the stress.
[0030]
Another object of the present invention is to provide an X-ray mask capable of preventing fog exposure by a simple method that does not affect the accuracy of a circuit pattern, and a method of manufacturing the X-ray mask.
[0031]
[Means for Solving the Problems]
According to one aspect of the present invention In the method of manufacturing an X-ray mask, an etching mask having a thickness defined by the thickness of the X-ray absorber and the required pattern accuracy is arranged.
[0034]
According to the above one aspect The method of manufacturing an X-ray mask isotropically etching an etching mask for forming a pattern on an X-ray absorber. May .
[0035]
According to another aspect of the invention The X-ray mask uses platinum or a compound thereof, chromium nitride, or chromium nitride oxide as an etching mask or an etching stopper of tungsten or an X-ray absorber containing tungsten as a main component.
[0039]
According to another aspect of the invention The X-ray mask is placed on the patterned X-ray absorber , Formed so as not to cover the entire X-ray absorber It has a secondary electron generation suppressing layer.
[0040]
According to another aspect above X-ray mask is the above Specifies that the secondary electron generation suppressing layer is a layer containing carbon as a main component. May .
[0041]
According to another aspect above The manufacturing method of the X-ray mask includes: the above Forming a pattern of the secondary electron generation suppressing layer containing carbon as a main component by etching the X-ray absorber with an etching gas; It is defined that the film is formed by a step of forming a film to be formed.
[0044]
According to other aspects of the invention X-ray mask , The rest As means for suppressing the generation of residue, a diffusion suppressing layer is disposed between the X-ray absorber and the etching stopper or between the etching mask and the X-ray absorber.
[0045]
According to the above and other aspects X-ray mask In the above, the diffusion suppressing layer may be a surface oxide layer formed between the etching mask and the X-ray absorber. .
[0046]
According to the above and other aspects X-ray mask , X A layer which is etched under the X-ray absorber etching conditions is provided between the X-ray absorber film and the etching mask or etching stopper of the X-ray absorber. May be .
[0047]
According to the above and other aspects X-ray mask so Is the above The layer etched under the etching conditions of the X-ray absorber contains silicon such as SOG or silicon oxide. May .
[0048]
According to yet another aspect of the invention X-ray mask , The rest It defines that the surface roughness of the X-ray absorber is controlled as means for suppressing the generation of residue.
[0049]
A method for manufacturing an X-ray mask according to another aspect of the present invention is directed to the above-described other aspects. X-ray mask manufacturing method And As means for suppressing the generation of residues, it is specified that the etching of the X-ray absorber is controlled by anisotropic etching and isotropic etching.
[0050]
A method for manufacturing an X-ray mask according to still another aspect of the present invention is directed to the above-described other aspects. X-ray mask manufacturing method And As means for suppressing the generation of residues, it is defined that an X-ray mask having the surface to be etched facing downward is vibrated by means such as an ultrasonic vibrator.
[0051]
According to yet another aspect of the invention In the manufacturing method of the X-ray mask, when the absorber of the X-ray mask is etched, the etching is terminated according to the detected value of the transmitted light of the X-ray mask.
[0064]
[Action]
Of the present invention According to one aspect In the method of manufacturing an X-ray mask, since the thickness of the etching mask is a minimum thickness defined by the thickness of the X-ray absorber and the required accuracy, when etching the etching mask, The dimensional accuracy of the etching mask can be maintained regardless of whether the etching is anisotropic or isotropic. As a result, dimensional accuracy at the time of etching the X-ray absorber can be maintained.
[0066]
Also, According to the above one aspect X-ray mask manufacturing method so Is ,etc Since the X-ray absorber is etched using the anisotropically etched etching mask, the side walls of the absorber can be etched obliquely instead of vertically. Therefore, there is a variation in the thickness of the absorber depending on the location of the pattern, which is called an X-ray phase shift effect. When The phase of the X-ray passing through the location changes, and a diffraction phenomenon occurs. As a result, a fine pattern can be transferred.
[0067]
In addition, the present invention According to other aspects X-ray mask so Since platinum and its compounds have a large etching selectivity when etching with an X-ray absorber containing tungsten, the X-ray absorber can be easily etched. In addition, since chromium nitride and chromium nitride oxide have a high selectivity with respect to the X-ray absorber containing tungsten, they can be used as an etching mask or an etching stopper when patterning the X-ray absorber like platinum and its compounds. Are better.
[0071]
In addition, the present invention According to another aspect Since the X-ray mask is provided with the secondary electron suppressing layer on the X-ray absorber on which the pattern is formed, the excitation of the secondary electrons by X-rays is performed when the pattern is transferred using the completed X-ray mask. Thus, it is possible to prevent a decrease in pattern accuracy due to exposure of secondary electrons.
[0072]
Also, According to another aspect above X-ray mask is the above Since the layer containing carbon as the main component is used as the secondary electron suppressing layer, the suppression of the excitation of the secondary electrons by the X-rays is efficiently performed, and the deterioration of the pattern accuracy due to the exposure of the secondary electrons can be prevented.
[0073]
Also, According to another aspect above X-ray mask manufacturing method so Is , Charcoal As a method for forming a secondary electron suppressing layer mainly composed of silicon, a film containing carbon is formed by changing the components of the etching gas after the etching of the X-ray mask pattern is completed. An electron suppression layer can be formed.
[0076]
In addition, the present invention According to other aspects Since the X-ray mask is provided with the diffusion suppressing layer so that the X-ray absorber and the etching mask or the X-ray absorber and the etching stopper are independent so as not to be mixed with each other, the generation of the etching residue which is easily generated in the diffusion layer portion is suppressed. Can be suppressed.
[0077]
Also, According to the above and other aspects X-ray mask so Arranges a step of annealing the X-ray absorber before the step of forming the etching mask on the X-ray absorber To form a surface oxide layer Therefore, formation of a diffusion layer between the X-ray absorber and the etching mask due to heat is prevented, and generation of residues can be suppressed.
[0078]
Also, According to the above and other aspects Since the X-ray mask has a layer which is etched under the same conditions as the X-ray absorber between the X-ray absorber and the etching stopper or between the X-ray absorber and the etching mask, the X-ray absorber and the etching stopper are provided. Alternatively, since the mixing of the X-ray absorber and the etching mask can be suppressed, the generation of residues can be suppressed.
[0079]
Also, According to the above and other aspects The X-ray mask is etched under the same conditions as the X-ray absorber made of tungsten or a tungsten compound Layers and Then, since the layer containing silicon is used, the layer can be formed by a simple method, and generation of residues can be suppressed.
[0080]
In addition, the present invention According to another aspect Since the X-ray mask controls the surface roughness of the X-ray absorber, it is difficult to etch the etching mask material having the concave portions as in the related art, so that the residues remaining in the concave portions are eliminated.
[0081]
In addition, the present invention According to another aspect According to the method of manufacturing an X-ray mask, anisotropic and isotropic etching is controlled in the step of etching the X-ray absorber, so that a needle-like residue which is easily formed in highly anisotropic etching is formed. Is etched from the side surface by isotropic etching, and is easily removed, and as a result, generation of residues can be suppressed.
[0082]
In addition, the present invention According to yet another aspect In the manufacturing method of the X-ray mask, the surface to be etched is turned downward at the time of etching, and the etching is performed while vibrating the X-ray mask. Therefore, residues generated on the surface are easily dropped and removed.
[0083]
In addition, the present invention According to yet another aspect In the manufacturing method of the X-ray mask, since the end point of the etching is detected by the change in the amount of transmitted light, And For example, an appropriate etching shape can be obtained even for samples of different lots and different thicknesses, and uniform etching with less variation between lots can be performed.
[0096]
【Example】
Embodiment 1 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing the structure of an X-ray mask according to one embodiment of the present invention. In the drawing, reference numeral 8 denotes a support ring, 9 denotes an etching stopper, and 10 denotes an AR coat film. The X-ray absorber 4 is made of W—Ti, the thickness is 0.5 μm (dx), the etching pattern dimension (dl) is 0.2 μm, and the required accuracy (a) is 10%. . When etching is performed using Cr as the etching mask 5 and using, for example, an ECR etching apparatus, the etching selectivity of Cr to W-Ti becomes 25 to 100. Here, the etching condition is the etching gas SF. ₆ -CHF ₃ The processing pressure is about 1 mTorr, the microwave output is 200 W, and the RF output is 13 to 50 W.
[0097]
First, the minimum thickness (demin) of the etching mask is determined. The thickness dx of the X-ray absorber is 0.5 μm, the selectivity r is 25 to 100, and dx / r ≦ de, so that 0.02 to 0.05 ≦ de. Next, the upper limit (demax) of the thickness dx of the X-ray absorber is determined. The minimum dimension (dl) of the pattern is 0.2 μm, the required accuracy (a) is 10%, and de ≦ 0.02 from de ≦ dl × a / 100. Therefore, the thickness of the etching mask in this case is appropriately set to 0.02 μm. The selectivity r is defined by the following equation under the same etching conditions.

[0098]
FIG. 2 is a diagram showing the relationship between the film thickness of the etching mask and the pattern formation of the X-ray absorber. In FIG. 2A, an etching mask having a thickness of de is formed on the X-ray absorber 4 and its dimensions are shown. The variation corresponds approximately to the thickness of the etching mask and is de. When the X-ray absorber is patterned by etching, and when the etching mask has ideally anisotropy and the angle of the side wall is 90 °, the X-ray absorber is further used by using this etching mask. If the side wall of the X-ray absorber is not affected by the side etch, the dimensional accuracy of the X-ray absorber after etching becomes extremely good. However, when the pattern is formed by isotropically etching the etching mask, the shape becomes as shown in FIG. 2A. When the X-ray absorber is etched using the etching mask having this shape, As shown in FIG. 2B, only an X-ray absorber pattern with inferior precision can be obtained. Further, in FIG. 2B, the etching condition is the severest in that the etching mask is etched and disappears at the same time when the etching of the X-ray absorber is completed. In this case, the pattern dimension is described as dl ± de by the minimum pattern dimension (dl) and the thickness de of the etching mask, and the thickness de of the etching mask simultaneously indicates a dimensional variation of the pattern. Here, the allowable dimensional variation is dl × a / 100 (a is the required pattern required accuracy%). Therefore, under the strictest condition that the etching mask is isotropically etched, the thickness of the etching mask needs to be at least the thickness / selectivity of the X-ray absorber in consideration of the etching selectivity. In addition, when the dimensional accuracy is taken into consideration, it can be seen that it is sufficient that the pattern minimum dimension × the required accuracy / 100 or less. This is because when the etching mask is sufficiently thick, the X-ray absorber can be etched. However, the accuracy of the etching mask pattern itself becomes low, and the accuracy affects the accuracy of the X-ray absorber. This suggests that the etching mask should be as thin as possible as much as possible.
[0099]
If the minimum pattern size is 0.1 μm, the required accuracy is 10%, and the thickness of the X-ray absorber is 0.5 μm, the thickness of the etching mask may be 0.01 μm or less. 50 or more are required. Thus, the etching selectivity can be optimized.
[0100]
Embodiment 2. FIG.
Hereinafter, another embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a sectional view showing the structure of an X-ray mask according to another embodiment of the present invention. In the figure, 5a is an etching mask (a) made of tungsten (W) and has a thickness of 0.01 μm, and 5b is an etching mask (b) made of chromium (Cr) and has a thickness of 0.03 μm. Here, the minimum pattern size is 0.1 μm and the dimensional accuracy is 10%. The thickness of the X-ray absorber 4 is 0.5 μm.
[0101]
As described above, when the etching mask is formed in multiple layers, it is possible to perform etching with higher precision than in the case of a single layer as in the first embodiment. As described in the first embodiment, when the etching mask is a single layer, the thinner the better, in order to etch the etching mask with high accuracy. However, when the etching mask is made thin, it is necessary to increase the etching selectivity between the etching mask and the X-ray absorber, and it becomes difficult to etch the X-ray absorber. On the other hand, when the etching mask has a multilayer structure, an etching mask having a controlled thickness is disposed immediately below the resist, and is accurately etched and patterned.Using the mask as a mask, the layers disposed sequentially are etched. As a result, a thick etching mask is formed for the X-ray absorber while maintaining the pattern accuracy.
[0102]
Next, a specific example will be described. In FIG. 3, the selectivity between the etching mask (b) 5b and the etching mask (a) 5a is about 10, and the selectivity between the X-ray absorber 4 and the etching mask (b) 5b is about 100. When the etching mask is a multilayer, the selectivity of the uppermost etch mask to the X-ray absorber is represented by the product of the selectivity of the adjacent layers, so that the selectivity of the etch mask (a) 5a to the X-ray absorber 4 is The product of their selectivity is about 1000. That is, based on the thickness of the X-ray absorber and the selectivity of 1000, the thickness of the etching mask (a) 5a may be 0.5 nm. Here, the upper limit of the thickness of the etching mask (a) 5a may be set to 0.01 μm or less even in consideration of the condition having the lowest pattern accuracy and the case where isotropic etching is performed. As described above, by using the multilayered etching mask, the selectivity between the etching mask immediately below the resist and the X-ray absorber is increased, so that a highly accurate etching pattern can be obtained.
[0103]
Embodiment 3 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 4 shows an X-ray mask etching method according to an embodiment of the present invention. In the figure, the structure from the resist pattern 6 'to the etching stopper 9 is shown, and the membrane and the like disposed below it are omitted. In the figure, (a) shows a resist pattern, (b) shows a state when the etching mask 5 is isotropically etched, and (c) shows a state when the X-ray absorber is etched. As shown in this figure, when the etching mask 5 is isotropically etched, the side wall of the etching mask becomes oblique. When the X-ray absorber is etched in this state, the side wall of the X-ray absorber also becomes oblique. Thus, when the thickness of the X-ray absorber varies depending on the location of the pattern, the phase of the X-ray passing therethrough changes (the phase shift effect at the time of X-ray exposure). Therefore, blurring is reduced at the edge of the pattern due to the X-ray diffraction phenomenon, and a fine pattern can be transferred.
[0104]
Embodiment 4. FIG.
Hereinafter, an embodiment of the present invention will be described. In FIG. 1, when platinum or a compound of platinum is used as the etching mask 5 or the etching stopper 9, the etching of tungsten or the X-ray absorber containing tungsten as a main component becomes easy. This means that when etching an X-ray absorber containing tungsten, a fluorine-based gas is mainly used, and when an etching mask containing platinum is used, a chlorine-based gas is used. This is because the etching gas is difficult to be etched by a system gas, and the platinum is hard to be etched by a fluorine gas, so that the etching selection ratio is increased. When a platinum-based material is used as the etching stopper, it is necessary to remove the etching stopper last. Platinum not only facilitates etching of tungsten but also can be used as an X-ray absorber, and therefore, an etching mask and an etching stopper under a pattern also function as an X-ray absorber.
[0105]
Embodiment 5 FIG.
Hereinafter, another embodiment of the present invention will be described. In FIG. 1, when chromium nitride or chromium nitride oxide is used for the etching mask 5 and the etching stopper 9, the etching of the X-ray absorber becomes easy. This is because the tungsten-based gas is easily etched by a fluorine-based gas and the chromium-based gas is easily etched by a chlorine-based gas, and the opposite gases are hardly etched by each other. Further, since the chromium nitride oxide film is transparent, it can be used as an etching stopper and an AR coat. Therefore, the transmittance of the alignment light increases, the alignment becomes easy, and the etching stopper does not have to be removed, so that the process can be simplified.
[0106]
Embodiment 6 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 5 is an overall configuration diagram of an etching apparatus which is one of the X-ray mask manufacturing apparatuses according to the embodiment of the present invention. This device is an ECR etching device, in which the etching gas introduced into the vacuum vessel is given a kinetic energy to the electrons by an electromagnetic coil arranged outside the vacuum vessel, and a plasma having a high ionization rate is generated by cyclotron resonance. The object is etched. FIG. 6 shows a part of a configuration of an apparatus for manufacturing an X-ray mask according to an embodiment of the present invention, mainly showing a configuration centering on a stage for mounting an X-ray mask wafer as an object to be etched. . In the drawing, 11 is a packing made of a metal material having high thermal conductivity such as copper or aluminum, 12 is a cooling stage, 13 is a wafer holder, and 14 is a gas hole for cooling. The arrows in FIG. 5 indicate the gas flow, and the part a indicates the location of gas leakage from the back surface of the cooling stage.
[0107]
As shown in FIG. 6, packing 11 is interposed between the cooling stage 12 and the wafer holder 13 of the X-ray mask. When the X-ray mask is patterned in such a configuration, the leakage of the cooling gas is small, and the cooling efficiency is increased. For example, when etching at a processing pressure of 1 mmTorr, a cooling gas pressure of about 0.5 Torr was conventionally obtained by flowing a cooling gas at a flow rate of 1 sccm. However, by using the packing of the present invention, the cooling gas pressure was reduced to about 2 Torr. , And as a result, the pressure could be controlled to be constant, so that the heat conduction was kept constant and the cooling efficiency was improved. When the gap between the wafer 1 and the cooling stage 12 is 0.1 mm, if the cooling gas can be maintained at 1 to 2 Torr, desired cooling can be performed.
[0108]
In this figure, the packing 11 reaches the upper surface of the X-ray mask, that is, the surface in contact with the wafer holder 13, but may be only the back surface of the mask, that is, the surface in contact with the cooling stage 12. However, if the packing is wrapped around the top of the mask, the packing is well fixed to the X-ray mask. The cooling efficiency increases.
[0109]
Embodiment 7 FIG.
Hereinafter, another embodiment of the present invention will be described with reference to the drawings. FIG. 7 shows a part of the configuration of an etching apparatus which is an apparatus for manufacturing an X-ray mask according to another embodiment of the present invention. In the figure, reference numeral 15 denotes a polymer film. This film may be applied by a spinner or the like in the same manner as a resist or the like, or a film-like film may be cut and attached, or grease may be applied to the back surface.
[0110]
When etching is performed in such a configuration, the polymer film fills the fine grooves (irregularities) between the wafer and the stage, so that the cooling gas leaks less, the cooling efficiency can be increased, and the X-ray absorber can be improved. Can be improved in etching shape.
[0111]
Embodiment 8 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 8 shows a part of the structure of an etching apparatus which is an apparatus for manufacturing an X-ray mask according to an embodiment of the present invention. In the figure, 16 is a cooling stand, and 17 is a spacer. In the figure, (a) shows a case where a back-etched X-ray mask is mounted, and (b) shows a case where a wafer-state X-ray mask is mounted. FIG. 9 shows a part of the configuration of an etching apparatus according to another embodiment of the present invention. FIG. 9 shows a configuration in which an X-ray mask with the support ring 8 attached is mounted.
[0112]
As described above, the spacer 17 is arranged on the back surface of the X-ray mask, and the heat conduction between the cooling stage 12 and the wafer 1 is improved. By performing etching with such a configuration, it is possible to cope with X-ray masks having various shapes, and etching can be performed only by changing the height of the spacer 17 or changing the shape of the cooling stage 12. Therefore, a manufacturing process can be selected without being particular about the shape of the X-ray mask. Note that the larger the contact area of these spacers and cooling stages, the smaller the loss of heat transfer, so the smoother the surface, the better. In addition, in order to make the spacer conform to the gap, it is better that the dimensional accuracy of the spacer is high.
[0113]
Embodiment 9 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 10 is a process chart showing a method for manufacturing an X-ray mask according to an embodiment of the present invention. In the figure, reference numeral 18 denotes a film containing carbon. In the drawing, (a) shows a state before etching, (b) shows a state after etching the etching mask 5 and then etching of the X-ray absorber ends, and (c) shows a state when etching ends and contains carbon. A gas may be introduced and the film may be formed by a CVD method or may be formed by a sputtering method. Further, by changing the concentration of carbon contained in the etching gas and forming a film continuously with the etching, the process can be simplified. By forming such a carbon-based film, a film for preventing generation of secondary electrons such as photoelectrons and Auger electrons can be easily formed. Although a carbon film is used here, any substance having a small absorption cross-sectional area with X-rays, for example, a light element may be used. However, the absorption cross-section greatly varies depending on the absorption wavelength of X-rays. Even in the case of light elements, if the absorption edge is a K-shell or L-shell, the absorption of X-rays will increase. The substance may be selected in consideration of the above.
[0114]
Embodiment 10 FIG.
Hereinafter, an embodiment of the present invention will be described. In FIG. 10, when the X-ray absorber contains tungsten, the etching of the X-ray absorber includes SF ₆ And CF ₄ For example, a gas containing fluorine such as is used. At that time, for example, SF ₆ CHF ₃ Is added to perform etching. For example, using the ECR etching apparatus shown in FIG. ₆ And CHF ₃ The flow ratio of SF ₆ / CHF ₃ Etching is performed at 1/1/1/10. At this time, carbon-based precipitates adhere to the side walls of the pattern and protect the side walls against etching, so that highly anisotropic etching can be performed. In this manner, etching is performed, and when patterning is completed, CHF ₃ Increase the concentration of For example, SF in the flow ratio ₆ / CHF ₃ When the ratio is 1/20 to 0/20, the amount of carbon-based precipitates increases, and the pattern covers the pattern. Therefore, a film for preventing photoelectrons can be easily formed.
[0115]
Embodiment 11 FIG.
Hereinafter, an embodiment of the present invention will be described. For example, in FIG. 1, the interface between the etching mask 5 and the X-ray absorber 4 or the interface between the X-ray absorber 4 and the etching stopper 9 is usually mixed with each other in atomic units. When etching with high selectivity and high anisotropy is performed in a state where they are mixed with each other, residues may be generated. Therefore, if they are not mixed with each other, generation of residues can be suppressed.
[0116]
In FIG. 1, when the etching stopper 9, the X-ray absorber 4, and the etching mask 5 are formed, generally two or more of these layers are continuously formed by the same apparatus in order to simplify the process. ing. However, since the film is usually formed in a vacuum state, the surface is in an active state at the time of completion of the film formation. Will mix. When etching with high anisotropy is performed in a state having the mixed layer, residues are easily generated. Therefore, the film is not continuously formed by the same apparatus, but is exposed to the air once after the film is formed, and a layer (several nm) having low surface activity is formed by oxidation or adsorption, and the layer having low activity is diffused. By using the suppression layer, mixing at the atomic level is eliminated when the next film formation is performed, and generation of residues can be suppressed.
[0117]
Embodiment 12 FIG.
Hereinafter, an embodiment of the present invention will be described. In FIG. 1, usually, after forming the X-ray absorber 4 and the etching mask 5, annealing at 200 to 400 ° C. is performed for stress control. However, in this method, the interface between the X-ray absorber 4 and the etching mask 5 is diffused due to the annealing step, and as a result, the interfaces are mixed to form a diffusion layer of several tens nm. Since the etching conditions change in the diffusion layer, residues during etching are likely to be generated. Therefore, annealing for controlling the stress is performed after forming the X-ray absorber to eliminate the diffusion layer, and a surface oxide layer of several atomic layers (several nm) is formed on the surface of the X-ray absorber by annealing. A diffusion suppressing layer. Accordingly, when the etching mask is formed after that, the interface is prevented from being mixed with each other, and the generation of the residue can be prevented.
[0118]
Embodiment 13 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 11 shows a sectional structure of an X-ray mask according to another embodiment of the present invention. In the figure, reference numeral 19 denotes a thin film which is etched under the same conditions as those for etching the absorber, for example, tantalum (Ta). With this thin film 19, the etching mask 5 and the X-ray absorber 4, or the X-ray absorber 4 and the etching stopper 9 (usually ITO) do not mix with each other. Further, since the thin film 19 is etched under the same conditions as the absorber, ordinary etching of the absorber may be performed. Further, Ta can be relatively easily etched by a chlorine-based gas or a fluorine-based gas, so that even if a mixed layer caused by Ta is formed, it can be easily removed by etching. Further, the presence of the thin film 19 can suppress generation of residues.
[0119]
Embodiment 14 FIG.
Hereinafter, an embodiment of the present invention will be described. In FIG. 11, when an absorber containing tungsten is used, when a film containing silicon such as SOG (spin-on-glass) is used as the thin film 19 in the drawing, this film can be etched under the same conditions as tungsten. Its etch rate is slightly faster than that of tungsten. Therefore, the SOG layer is easily etched isotropically, so that side etching is easily performed. Therefore, the residue of the absorber due to the remaining etching mask is easily removed by the side etching of the film 19 containing silicon, and as a result, the residue of the absorber is etched. In addition, since the thin film 19 between the absorber and the etching stopper is also side-etched, residues of the absorber tend to fall down, and as a result, the residues themselves are easily etched. Therefore, residue generation can be suppressed.
[0120]
Embodiment 15 FIG.
Hereinafter, an embodiment of the present invention will be described. In FIG. 1, when the surface of the X-ray absorber 4 has irregularities of 0.1 μmRmax or more, an etching mask 5 is formed on the X-ray absorber 4, and after the resist 6 is patterned, the etching mask 5 is etched. Then, the material of the etching mask 5 is likely to remain in the concave portions. As a result, when the X-ray absorber 4 is etched, residues of the X-ray absorber 4 are likely to be generated. Therefore, the film can be formed so that the surface of the X-ray absorber 4 has a smooth surface of at least 0.05 μmRmax or an amorphous absorber, so that the surface can be formed relatively smoothly. In addition, since the normal absorber is a thin film having a columnar structure, the surface irregularities are large, but in this state, isotropic etching is performed to smooth the surface, or the surface of the absorber is polished and smoothed, After that, if the etching mask 5 is formed, the etching mask 5 remaining in the concave portion is eliminated, so that the generation of the residue when the X-ray absorber 4 is etched can be suppressed.
[0121]
Embodiment 16 FIG.
Hereinafter, an embodiment of the present invention will be described. In FIG. 1, if the etching mask 5 is left even slightly, a residue of the X-ray absorber 4 is generated when the X-ray absorber 4 is etched with high anisotropy. FIG. 12 shows a process in which an etching mask remains in a concave portion and a residue is generated, and a step of removing the generated residue. In the figure, an etching mask 5 and a patterned resist film 6 are formed on an uneven X-ray absorber 4 in a step (a). The unevenness of the etching mask 5 is also formed following the unevenness of the X-ray absorber 4. When the etching mask 5 is patterned in the step (b), the etching mask of the concave portion of the X-ray absorber 4 is hardly etched, and when the X-ray absorber 4 is etched in the step (c), the concave portion of the X-ray absorber 4 is not etched. Is regarded as a part of the pattern, and appears as a residue in the step (d) where the etching mask 5 is removed. As in the present invention, when the absorber is etched, by controlling the highly anisotropic etching and the isotropic etching, the portion of the X-ray absorber immediately below the remaining etching mask is etched from the side (step). (D ')), the generation of residues is suppressed (step (e')).
[0122]
Embodiment 17 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 13 shows a part of the structure of an etching apparatus which is an apparatus for manufacturing an X-ray mask according to an embodiment of the present invention. In the figure, reference numeral 20 denotes an ultrasonic transducer, and reference numeral 21a denotes an X-ray mask in a wafer state.
[0123]
When patterning is performed by the etching apparatus having such a configuration, the wafer vibrates and the pattern surface faces downward, so that even if an etching residue is generated, the residue is likely to fall, thereby improving the final pattern accuracy. In addition, when the measures of claims 11 to 17 are also performed, generation of residues can be further suppressed. Another feature is that dust generated for other reasons is easily removed. Note that ultrasonic waves are applied during etching and before and after etching to remove residues efficiently.
[0124]
Embodiment 18 FIG.
Hereinafter, another embodiment of the present invention will be described with reference to the drawings. FIG. 14 shows a part of the configuration of an etching apparatus according to an embodiment of the present invention. In the figure, 21b is an X-ray mask in a membrane state, and 22 is a gas valve.
[0125]
If an etching apparatus having such a configuration is used and a cooling gas is intermittently flowed, the mask in a membrane state, in particular, the membrane portion vibrates, so that even if a residue is generated, the residue is more likely to fall. Therefore, patterning with high dimensional accuracy can be performed.
[0126]
Embodiment 19 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 15 shows a part of the configuration of an X-ray mask manufacturing apparatus according to an embodiment of the present invention. In the figure, reference numeral 25 denotes a detector for detecting a laser beam 24 emitted from a laser oscillator 23. In the drawing, (a) shows the state before the etching of the X-ray absorber, and (b) shows the state when the etching of the X-ray absorber is completed. It should be noted that the irradiation place of the laser beam 24 is preferably a wide cut pattern such as an alignment mark provided outside the pattern. The laser beam 24 is, for example, a He-Ne laser having a wavelength of 633 nm, a 780 nm semiconductor laser, or the like.
[0127]
When etching is performed by the apparatus having such a configuration, when the etching of the absorber is not completed, the laser beam 24 is blocked by the X-ray absorber 4 and does not transmit, and the light does not reach the detector 25. However, when the pattern of the absorber is formed, the laser light 24 passes through the membrane 2 and is detected by the detector 25. Even if the same material is used, the etching rate changes depending on the pattern width. Therefore, the relationship between the pattern width and the etching rate is determined in advance, and after detecting light with the detector 25 so as to obtain a desired pattern, an appropriate overetching is performed. Is applied. Thereby, the circuit pattern including the fine pattern can be appropriately etched. Further, variation in etching time due to unevenness in film thickness during sputtering is reduced, and an X-ray mask with good dimensional accuracy can be manufactured.
[0128]
Embodiment 20 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 16 is a sectional view showing the structure of the X-ray mask according to the embodiment of the present invention. In the figure, reference numeral 26 denotes an AlZnOx film, which is formed on the membrane 2 by sputtering to a thickness of about 0.1 μm.
[0129]
In the X-ray mask manufactured in this manner, the AlZnOx film 26 is transparent and has electrical conductivity, so that it functions as an antireflection film for the membrane 2 made of SiC, improves visible light transmittance, and improves the antistatic film. Also works as. Further, since the main component of the AlZnOx film 26 is Al, which is a light element, the transmittance of X-rays is higher than that of conventionally used ITO. For example, the anti-reflection film is changed from ITO to AlZnO. ₃ By changing to (in the case of x = 3 of AlZnOx), the X-ray transmittance is improved by about 10 to 30%. Further, when a tungsten-based material was used for the absorber, AlZnOx showed sufficient ability as an etching stopper at the time of etching the absorber.
[0130]
In this embodiment, an example of the AlZnOx film is described. However, similarly to the AlZnOx film, an improvement in the X-ray transmittance can be realized by using a SnSbOx or SnOx film. In this case, although the structure is a heavy element rather than AlZnOx, it has an antistatic effect due to conductivity.
[0131]
Embodiment 21 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 17 is a diagram showing a manufacturing process of the X-ray mask according to the embodiment of the present invention. In the figure, reference numeral 27a denotes an X-ray mask for a manufacturing process, in which silicon is back-etched. Reference numeral 28a denotes a silicon wafer on which warpage has been measured in advance, and a wafer for stress measurement X-ray mask monitor having a membrane formed on one surface thereof. In these, the W-Ti absorber is formed by the same apparatus and the same batch, 27b is an X-ray mask after the film formation, and 28b is a silicon wafer after the film formation. At that time, a sputtering apparatus provided with a self-revolution type stage was used so that the X-ray absorber film 4 having the same characteristics was formed, and the distance between the substrate and the target was made constant. After the film formation, the warpage of the stress measurement X-ray mask monitor wafer 28b was measured, and annealing was performed. After the annealing, the warpage of the monitor wafer was measured again, and the final annealing temperature at which the stress of the X-ray absorber 4 became 0 was determined from the measurement results. In the case of the W—Ti absorber film, the final annealing temperature is easy to determine because the annealing temperature is proportional to the stress change. Then, the X-ray mask in the process was annealed at the final annealing temperature. This does not depend on the reproducibility between batches of the sputtering apparatus. An X-ray mask on which a low-stress absorber is formed can be obtained.
[0132]
In the above embodiment, the example in which the support ring is not bonded to the silicon substrate is shown. However, as shown in the manufacturing process of the X-ray mask in FIG. 18, the membrane 2 is formed by the X-ray mask in the process. Even when the silicon substrate 1 is bonded to the support ring 8, if the X-ray mask monitor wafer for stress measurement is arranged in the same sputtering apparatus, the annealing temperature for obtaining a low stress absorber is obtained in the same manner. Can be determined. In the drawings, 29a shows an X-ray mask for a manufacturing process to which a support ring is joined, and 29b shows a state in which an X-ray absorber is formed on the X-ray mask.
[0133]
Further, in the above embodiment, an example was described in which an annealing step was used as a method for obtaining a low stress absorber. However, as shown in FIG. May be performed by ion implantation. In this case, the final ion dose is determined from the measurement of the warpage of the monitor wafer, and the dose of that value is applied to the X-ray mask during the process to obtain a zero stress absorber.
[0134]
Furthermore, in the above embodiment, an example was described in which a silicon substrate, which is the same material as the substrate for the X-ray mask manufacturing process, was used as the monitor wafer. The material is not limited to the silicon substrate as long as the material has a clear correlation. The use of a silicon substrate has the effect that monitoring can be performed at low cost.
[0135]
Embodiment 22 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the above-described Embodiment 21, an example was described in which a silicon wafer was used as the X-ray mask monitor wafer for stress measurement. However, although it is more expensive than a silicon wafer for more accurate stress monitoring, it is similar to an X-ray mask for a manufacturing process. It is desirable to use a wafer which has been back-etched. FIG. 20 is a view showing a manufacturing process of the X-ray mask according to the embodiment of the present invention. In the figure, reference numeral 42a denotes a back-etched monitor wafer before film formation, and reference numeral 42b denotes a back-etched monitor wafer after film formation. The back-etched wafer is usually dish-shaped due to tensile stress. If a change in stress is measured based on this warped state, a stress close to that of an actual process can be measured with high accuracy, and therefore, a reduction in stress can be achieved. The manufacturing X-ray mask substrate 1 is made of a silicon wafer having a thickness of about 2 mm, and the monitor wafer 1 'is a silicon wafer having a thickness of about 0.4 mm. Since the thinner the wafer, the more accurately the stress can be measured, the change in stress due to the absorber film formation and annealing can be measured with a monitor wafer with high sensitivity, and more accurate stress control becomes possible.
[0136]
Although FIG. 20 describes that the annealing temperature at which the stress becomes 0 is determined as the stress control process, this is the same as in Example 21. Further, as shown in FIG. 19 of the twenty-first embodiment, the stress of the absorber film may be adjusted by ion implantation. In this case, the final ion dose is determined from the warpage measurement of the back-etched monitor wafer, and the dose of that value is applied to the X-ray mask in the process to obtain a zero stress absorber.
[0137]
Embodiment 23 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Example 21 corresponds to an X-ray mask having the simplest structure, or a reduction in stress focusing only on the X-ray absorber. However, in the manufacturing process of an X-ray mask including a film that finally forms the same pattern as the X-ray absorber, it is necessary to control the stress of the films collectively. FIG. 21 shows a part of the manufacturing process of an X-ray mask provided with a film forming the same pattern as the X-ray absorber. (A) in the figure shows the state of the substrate before forming the X-ray absorber. Here, only the membrane 2 and the antireflection film (AR coat) 10 are formed on the silicon wafer 1. FIG. 3B shows the state of the X-ray mask in which a desired film before annealing is formed on the substrate. At this stage, the Cr etching stopper 9, the flattening film 50 made of silicon oxide, and the W—Ti absorber film 4 are formed.
[0138]
Next, the annealing step will be described. The annealing step utilizes the principle of controlling the stress of the X-ray absorber described in Japanese Patent Application No. 5-233187. FIG. 22 is a diagram showing the relationship between the annealing temperature and the stress, and illustrates the change in stress during the annealing process. In the figure, the horizontal axis represents temperature, the vertical axis represents stress or a physical quantity correlated with the stress (for example, a measured value such as the height or curvature of warpage), the + direction represents tensile stress, and the − direction represents compressive stress. Also, in the figure, A indicates the stress state of the X-ray mask before the start of annealing after film formation at room temperature, B indicates the annealing effect manifestation point, C indicates the annealing stop point, and D indicates the annealing completion point at room temperature. I have.
[0139]
When the X-ray mask shown in FIG. 21B is heated, the stress changes from A to B in FIG. 22 due to the difference in the coefficient of thermal expansion between the substrate material silicon and the film such as the absorber. As the heating temperature is further increased, at point B, the stress moves away from line AB. This is because an annealing effect is exhibited by a change in crystal structure, desorption of gas taken into the absorber, and the like.
[0140]
By the way, the target state is point D. To determine this point, at the time when the straight line AB is determined, a straight line D parallel to the straight line AB and passing through the annealing completion point D at room temperature at which the stress or the physical quantity correlated with the stress becomes zero. By determining -D 'in advance, the stress is monitored even after passing point B, and at the point when point C passes point D and intersects a straight line DD' parallel to straight line AB, By stopping the annealing (stopping the heating) and cooling the substrate to room temperature, the state at point D is obtained. That is, at the point D, the stress state is the same as that in FIG.
[0141]
Therefore, according to the above embodiment, the stress or the physical quantity correlated to the stress is measured and monitored during the annealing step of the X-ray mask in which all the desired films on which the same pattern as the X-ray absorber is formed are laminated. Since the completion time of the annealing can be determined, the total stress of the layers (absorbers and etching stoppers) that are patterned with good reproducibility can be reduced.
[0142]
Embodiment 24 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. This is another embodiment in which the stress is reduced by annealing the X-ray mask in which a plurality of predetermined layers in which the same pattern as the X-ray absorber is formed as in Embodiment 23. FIG. 23 is a diagram showing the relationship between the annealing temperature and the stress. In the figure, the horizontal axis represents the annealing temperature, the vertical axis represents the stress or a physical quantity correlated with the stress (for example, a measured value such as the height or curvature of the warp), the + direction represents the tensile stress, and the − direction represents the compressive stress. The figure shows the relationship between the temperature of the annealing treatment and the stress value at that temperature, as compared with the temperature after the film formation. In certain samples 1 to 3, annealing is performed at two temperatures θM1 and θM2 lower than the expected annealing temperature θ, and the stress is measured each time. The final annealing temperature θa is determined for each sample or batch from the intersection of the straight line connecting these two stress measurement results and the zero stress line. Here, θa1, θa2, and θa3 are determined for Samples 1 to 3, and annealing is performed at the determined temperature, whereby a low-stress laminated film (including an absorber) is obtained.
[0143]
In the above embodiment, the temperature lower than the annealing temperature θ is set to two points of θM1 and θM2, but three or more points may be used as long as there are at least two points. It goes without saying that the accuracy of the determined temperature is improved when there are many measurement points.
[0144]
Embodiment 25 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 24 is a view showing a manufacturing process of the X-ray mask according to the embodiment of the present invention. In the figure, reference numeral 43a denotes an X-ray mask for a manufacturing process, in which silicon is back-etched, and an AR coat 10 and a membrane 2 are formed. 44a indicates a back-etched monitor wafer before film formation, and 44b indicates a back-etched monitor wafer after film formation. On the monitor wafer 44a before film formation, the film formation of the AR coat 10 was omitted. Next, on the membrane 2, the etching stopper 9, the flattening film 50, and the X-ray absorber 4 are formed under the same conditions as those of the manufacturing process X-ray mask 43a. A monitor wafer 44b is obtained at the same time as the mask 43b. Here, the final annealing temperature is determined using the monitor wafer 44b, and the X-ray mask substrate is also annealed at that temperature. The procedure for obtaining the final annealing temperature from the monitor wafer may be the same as that of the embodiments 23 and 24.
[0145]
In the above embodiment, the final annealing temperature is determined using the monitor wafer after the formation of a large number of films, and the X-ray mask substrate in the process is annealed based on the final annealing temperature. In addition to annealing, the processing at the intermediate temperature in Examples 23 and 24 using the monitor wafer, for example, the processing at θM1 and θM2 in Example 24 may be performed in the same manner as the monitor wafer.
[0146]
Embodiment 26 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 25 is a process chart showing a method for manufacturing an X-ray mask according to the present invention. In the drawing, reference numeral 30 denotes an absorber etching intermediate layer having a high selectivity with respect to the X-ray absorber, such as Cr or Al. ₂ O ₃ It is. In the step (a), an etching stopper 9, an X-ray absorber 4a from the first film forming step, and a resist film 6 are formed on an X-ray transparent substrate (for example, a silicon substrate) 1 which has been back-etched in advance. At this time, the intermediate layer 30 having a high selectivity is inserted between the resist film 6 and the X-ray absorber 4a. In the step (b), a resist film 6 for forming a first pattern is formed, the intermediate layer 30 is etched using the resist film 6 as an etching mask, and then the intermediate layer on which the first pattern is formed is used as an etching mask. By etching the first X-ray absorber film 4a, a thick fog exposure preventing X-ray absorber pattern is formed. In the step (c), a second X-ray absorber film 4b is formed thereon, and the resist 6 is applied again. As in the first pattern forming step, an intermediate layer 30 having a high selectivity with respect to the X-ray absorber is inserted between the resist film 6 and the X-ray absorber 4b. In the final step (d), a resist film is patterned to form a second pattern, the intermediate layer 30 is etched using the resist film as an etching mask, and then the intermediate layer 30 on which the second pattern is formed is used as an etching mask. The X-ray absorber circuit pattern 7 is obtained by etching the second X-ray absorber film 4b.
[0147]
Embodiment 27 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 26 is a process chart showing a method for manufacturing an X-ray mask according to the present invention. In the step (a) in the figure, after forming the X-ray absorber 4a in the first film forming step, a resist film 6 is applied thereon. In the step (b), when forming the pattern of the X-ray absorber 4a in the first film forming step, the X-ray absorber 4a is etched to a predetermined thickness. For example, after forming a 1 μm X-ray absorber, the film is etched to 0.5 μm. Next, in a step (c), the resist 6 is applied again to form a circuit pattern. In the final step (d), a desired X-ray absorber circuit pattern 7 is obtained by etching using the patterned resist film 6 as an etching mask.
[0148]
As described above, when the X-ray absorber for preventing fog exposure is formed in advance, the X-ray absorber is etched to a certain thickness, and then the resist is re-coated, transferred, and etched. Since the fog exposure preventing X-ray absorber is formed before the formation, the stress of the fog exposure preventing X-ray absorber film does not affect the positional accuracy of the circuit pattern, and therefore, the accuracy is high. The circuit pattern can be formed, and the X-ray absorber film forming process is required only once.
[0149]
Embodiment 28 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 27 is a process chart showing a method of manufacturing an X-ray mask according to the present invention, in which a forward taper is provided in the X-ray fogging exposure preventing X-ray absorber in FIG. 25 of Embodiment 26. In the figure, in a step (a), an etching stopper 9, an X-ray absorber 4a from the first film forming step, and a resist film 6 are formed on a back-etched X-ray transparent substrate 1 in advance. At this time, the intermediate layer 30 having a high selectivity with respect to the X-ray absorber 4a is inserted between the resist film 6 and the X-ray absorber 4a. In the step (b), a resist film 6 for forming a first pattern is formed, the intermediate layer 30 is etched using the resist film 6 as an etching mask, and then the intermediate layer on which the first pattern is formed is used as an etching mask. The first X-ray absorber film 4a is etched. At this time, the side wall of the X-ray absorber is etched under a condition of forming a forward taper, for example, etching condition is controlled and relatively isotropic etching may be performed, and an angle of about 60 to 70 ° is provided. It is desirable to make it. As a result, a thick fog exposure preventing X-ray absorber pattern is formed. In the step (c), a second X-ray absorber film 4b is formed thereon, and the resist 6 is applied again. As in the first pattern forming step, an intermediate layer 30 having a high selectivity with respect to the X-ray absorber is inserted between the resist film 6 and the X-ray absorber 4b. In the final step (d), a resist film is patterned to form a second pattern. At that time, since the surrounding X-ray absorber has a forward taper, a uniform resist film can be formed at the time of resist application, and as a result, a highly accurate circuit pattern can be formed. Next, the X-ray absorber circuit pattern 7 is obtained by etching the intermediate layer 30 and then etching the second X-ray absorber film 4b using the intermediate layer 30 on which the second pattern has been formed as an etching mask.
[0150]
Embodiment 29 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 28 is a process chart showing a method for manufacturing an X-ray mask according to the present invention. In the figure, reference numeral 31 denotes a fog exposure prevention plate which is attached to the silicon substrate 1. With such a configuration, fog exposure can be prevented by a simple method, and the X-ray mask creation time and X-ray mask creation cost can be reduced. Further, by attaching the X-ray mask to the stepper so as not to go over the lower surface of the support ring, it becomes easy to mount the X-ray mask on the stepper. Further, since the attaching operation does not affect the accuracy of the circuit pattern and the alignment pattern, a highly accurate circuit pattern and an alignment pattern can be formed.
[0151]
Embodiment 30 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 29 is a process chart showing a method for manufacturing an X-ray mask according to the present invention. In the figure, 32 is an alkali-resistant resist, 33 is a heater, and 34 is a KOH solution. In the figure, a fog exposure prevention plate is prepared by plane anisotropic etching of a solution containing KOH of a silicon substrate (here, the (100) plane is used) so that the four corners of the opening have a right angle fog exposure prevention. A plate is obtained. This utilizes the property that the silicon substrate is difficult to dissolve in the order of (111) plane, (110) plane, and (100) plane in the solution containing KOH. By adjusting the center of each side of the opening to the direction in which it is difficult to dissolve on the surface that is easy to dissolve, a fog exposure prevention plate with four corners at right angles and no roundness can be manufactured.
[0152]
Embodiment 31 FIG.
Hereinafter, another embodiment of the present invention will be described with reference to the drawings. FIG. 30 is a process chart showing a method for manufacturing an X-ray mask according to the present invention. In the figure, 35 is SiC. In step (a), SiC35 is formed on both surfaces of the silicon wafer 1 by a CVD method. Next, in the step (b), the central part of the SiC on one side is removed by etching. For this, a light transfer method and a dry etching method were used. Next, in step (c), the window region is etched by immersing the substrate 1 in a saturated KOH solution 34 heated to 80 to 100 ° C. by the heater 33. For example, in the case of silicon having a thickness of 100 μm, etching is completed in about 30 minutes. The above process makes it possible to obtain a fog exposure preventive plate having an accurate size on the order of microns.
[0153]
Embodiment 32 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 31 is a process chart showing a method for manufacturing an X-ray mask according to the present invention. In the drawing, 36 is a prism having the same cross section as the size of the opening of the fog exposure preventing plate, and 37 is a rectangular X-ray shielding plate. In the step (a), for example, four glass X-ray shielding plates 37 each having a thickness of 200 μm are combined and joined along the prism 36. Next, in step (b), the prism 36 is pulled out. Finally, in step (c), the X-ray mask is mounted inside the support ring 8. As described above, since the X-ray shielding plate 37 made of glass is required to have the same surface roughness and flatness as those of the silicon wafer 1 and the support ring 8 in order to attach the silicon wafer 1 and the support ring 8 in contact with each other. As described above, it is possible to obtain a fogging exposure prevention plate that is simple and highly accurate, and in which the corners of the opening are completely perpendicular.
[0154]
【The invention's effect】
As mentioned above, Method for manufacturing X-ray mask according to one aspect of the present invention According to the method described above, since the thickness of the etching mask is as thin as the minimum thickness defined by the thickness of the X-ray absorber and the required accuracy, the etching at the time of forming the pattern of the etching mask However, dimensional accuracy can be maintained irrespective of anisotropy or isotropic property. As a result, the dimensional accuracy at the time of etching the X-ray absorber can be maintained, and a highly accurate X-ray mask can be provided with high yield.
[0156]
Also, Method for manufacturing X-ray mask according to the above aspect According to ,etc Since the X-ray absorber is etched using the anisotropically etched etching mask, the side walls of the absorber are obliquely etched. Therefore, when this X-ray mask is used, a fine pattern can be transferred due to a diffraction phenomenon at a pattern edge portion due to an X-ray phase shift effect.
[0157]
Also, as above X-ray mask according to another aspect of the present invention According to the method, platinum or a compound thereof has a large etching selectivity when etching with an X-ray absorber containing tungsten, so that the X-ray absorber can be easily etched. In addition, since chromium nitride and chromium nitride oxide have a high selectivity with respect to the X-ray absorber containing tungsten, they can be used as an etching mask or an etching stopper when patterning the X-ray absorber like platinum and its compounds. It is excellent and can provide a high-precision X-ray mask with high yield.
[0161]
Also, as above X-ray mask according to another aspect of the present invention According to the method, since the secondary electron suppressing layer is provided on the X-ray absorber on which the pattern is formed, the excitation of the secondary electrons by X-rays is suppressed when transferring the pattern using the completed X-ray mask. And high-accuracy pattern transfer becomes possible.
[0162]
Also, as above X-ray mask according to another aspect above According to , 2 Since a layer containing carbon as a main component is used as the secondary electron suppressing layer, the excitation of secondary electrons by X-rays is efficiently suppressed, and a pattern transfer with high accuracy can be performed.
[0163]
Also, as above X-ray mask manufacturing method according to another aspect According to , Charcoal As a method for forming a secondary electron suppressing layer mainly composed of silicon, a film containing carbon is formed by changing the components of the etching gas after the etching of the X-ray mask pattern is completed. An electron suppression layer can be formed, and high-precision pattern transfer becomes possible.
[0166]
Also, as above X-ray mask according to another aspect of the present invention According to the method, since the diffusion suppressing layer is provided between the X-ray absorber and the etching mask or between the X-ray absorber and the etching stopper, it is possible to suppress the generation of the etching residue which is easily generated in the diffusion layer portion, and to achieve the final transfer accuracy. Can be prevented from decreasing.
[0167]
Also, as above In the X-ray mask according to the above other aspects, Since the step of annealing the X-ray absorber is arranged before the step of forming the etching mask on the X-ray absorber, the formation of a diffusion layer between the X-ray absorber and the etching mask due to heat is prevented, In addition, a thin oxide layer is formed on the surface of the X-ray absorber, so that generation of residues can be suppressed, and a decrease in final transfer accuracy can be prevented.
[0168]
Also, as above X-ray mask according to the above and other aspects According to the present invention, a layer that is etched under the same conditions as the X-ray absorber is provided between the X-ray absorber and the etching stopper or between the X-ray absorber and the etching mask. Alternatively, since the mixing of the X-ray absorber and the etching mask can be suppressed, the generation of residues can be suppressed, and a decrease in final transfer accuracy can be prevented.
[0169]
Also, as above X-ray mask according to the above and other aspects According to the above, the etching is performed under the same conditions as the X-ray absorber made of tungsten or a tungsten compound. Layer Since a layer containing silicon is used, a layer can be formed by a simple method and generation of residues can be suppressed.
[0170]
Also, as above X-ray mask according to another aspect of the present invention According to the method described above, the surface roughness of the X-ray absorber is controlled, so that it is difficult to etch the etching mask material having the concave portions as in the prior art, so that residues remaining in the concave portions are eliminated, and the final transfer accuracy is reduced. Can be prevented.
[0171]
Also, as above X-ray mask manufacturing method according to another aspect of the present invention According to the method described above, in the step of etching the X-ray absorber, the anisotropic and isotropic etching is controlled to be performed. This makes it possible to form a high-precision name X-ray mask, thereby preventing a decrease in final transfer accuracy.
[0172]
Also, as above X-ray mask manufacturing method according to still another aspect of the present invention According to the method described above, the surface to be etched is turned downward at the time of etching, and the etching is performed while vibrating the X-ray mask, so that residues generated on the surface are easily dropped and removed, thereby preventing a decrease in final transfer accuracy. can do.
[0173]
Also, as above X-ray mask manufacturing method according to still another aspect of the present invention According to the method, the etching is terminated by the change of the transmitted light of the X-ray mask, so that an appropriate etching shape can be obtained even for samples of different lots and different thicknesses, and uniform etching with less variation between lots is performed. Thus, a highly accurate X-ray mask can be provided.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a structure of an X-ray mask according to embodiments 1, 4, 5, 11, 12, 15, and 16 of the present invention.
FIG. 2 is a principle diagram showing the relationship between the thickness of an etching mask and the formation of an X-ray absorber pattern according to Embodiment 1 of the present invention.
FIG. 3 is a sectional view showing a structure of an X-ray mask according to Embodiment 2 of the present invention.
FIG. 4 is a process chart showing a method for manufacturing an X-ray mask according to Embodiment 3 of the present invention.
FIG. 5 is an overall configuration diagram of an etching apparatus which is one of the X-ray mask manufacturing apparatuses according to Embodiment 6 of the present invention.
FIG. 6 shows a part of a configuration of an X-ray mask manufacturing apparatus according to a sixth embodiment of the present invention.
FIG. 7 shows a part of a configuration of an X-ray mask manufacturing apparatus according to a seventh embodiment of the present invention.
8A and 8B show a part of the configuration of an X-ray mask manufacturing apparatus according to Embodiment 8 of the present invention. FIG. 8A shows a case where a back-etched X-ray mask is mounted, and FIG. This shows a case where an X-ray mask is mounted.
FIG. 9 shows a part of a configuration of an apparatus for manufacturing an X-ray mask according to Embodiment 8 of the present invention.
FIG. 10 is a process chart showing a method for manufacturing an X-ray mask according to Embodiments 9 and 10 of the present invention.
FIG. 11 is a sectional view showing a structure of an X-ray mask according to Embodiments 13 and 14 of the present invention.
FIG. 12 is a view showing a step of removing a residue generated on an X-ray mask according to Embodiment 16 of the present invention.
FIG. 13 shows a part of the configuration of an apparatus for manufacturing an X-ray mask according to Embodiment 17 of the present invention.
FIG. 14 shows a part of the configuration of an apparatus for manufacturing an X-ray mask according to Embodiment 18 of the present invention.
FIG. 15 shows a part of the configuration of an apparatus for manufacturing an X-ray mask according to Embodiment 19 of the present invention. In the figure, (a) shows a state before etching of the absorber of the X-ray mask, and (b) shows a point in time when etching of the absorber is completed.
FIG. 16 is a sectional view showing a structure of an X-ray mask according to Embodiment 20 of the present invention.
FIG. 17 is a process chart showing an X-ray mask manufacturing process according to Embodiment 21 of the present invention.
FIG. 18 is a process chart showing an X-ray mask manufacturing process according to Embodiment 21 of the present invention.
FIG. 19 is a process chart showing an X-ray mask manufacturing process according to Embodiment 21 of the present invention.
FIG. 20 is a process chart showing an X-ray mask manufacturing method according to Embodiment 22 of the present invention.
FIG. 21 is a process chart showing an X-ray mask manufacturing method according to Embodiment 23 of the present invention.
FIG. 22 is a diagram illustrating a method for determining an annealing temperature of an X-ray mask according to Embodiment 23 of the present invention.
FIG. 23 is a diagram illustrating a method for determining an annealing temperature of an X-ray mask according to Embodiment 24 of the present invention.
FIG. 24 is a process chart showing an X-ray mask manufacturing method according to Embodiment 25 of the present invention.
FIG. 25 is a process chart showing an X-ray mask manufacturing method according to Embodiment 26 of the present invention;
FIG. 26 is a process chart showing an X-ray mask manufacturing method according to Embodiment 27 of the present invention.
FIG. 27 is a process diagram showing an X-ray mask manufacturing method according to Embodiment 28 of the present invention.
FIG. 28 is a sectional view showing an X-ray mask according to Embodiment 29 of the present invention.
FIG. 29 is a process diagram showing a method of manufacturing a fog exposure preventing plate for an X-ray mask according to Embodiment 30 of the present invention.
FIG. 30 is a process chart showing a method of manufacturing a fog exposure preventing plate for an X-ray mask according to Embodiment 31 of the present invention.
FIG. 31 is a process diagram showing an X-ray mask manufacturing method according to Embodiment 32 of the present invention.
FIG. 32 is a cross-sectional view showing the structure of a conventional X-ray mask.
FIG. 33 is a process chart showing a conventional method for manufacturing an X-ray mask.
FIG. 34 is a principle diagram of transferring a pattern using an X-ray mask.
FIG. 35 is a cross-sectional view showing a step of manufacturing a conventional X-ray mask having a fog exposure preventing function.
FIG. 36 is another process drawing showing the step of the conventional X-ray mask.
FIG. 37 is another sectional view showing the structure of a conventional X-ray mask.
[Explanation of symbols]
1 silicon substrate, 2 membrane (SiC film), 3 protective film (ITO film), 4 X-ray absorber film, 4a X-ray absorber film formed by the first film forming process,
4b X-ray absorber film formed by the second film forming step;
5 etching mask (Cr film), 5a etching mask (a),
5b etching mask (b), 6 resist film, 6 'resist pattern,
7 circuit pattern, 8 support ring, 9 etching stopper,
10 AR coat, 11 packing, 12 cooling stage,
13 Wafer holder, 14 Gas hole for cooling, 15 Polymer film,
16 cooling stand, 17 spacer, 18 carbon containing film,
19 a thin film etched under the same conditions as the absorber, 20 ultrasonic transducer,
21a X-ray mask in wafer state, 21b X-ray mask in membrane state,
22 gas valve, 23 laser oscillator, 24 laser light,
25 detector, 26 AlZnOx film, 27a X-ray mask for manufacturing process,
27b an X-ray mask for a manufacturing process having an X-ray absorber film formed thereon,
28a X-ray mask monitor wafer for stress measurement,
28b an X-ray mask monitor wafer for stress measurement on which an X-ray absorber film is formed,
29a X-ray mask in production with support ring,
29b an X-ray mask being manufactured with a support ring having an X-ray absorber film formed thereon,
30 intermediate layer for absorber etching, 31 fog exposure prevention plate,
32 alkali resistant resist, 33 heater, 34 KOH solution,
35 SiC, 36 prism, 37 X-ray shielding plate, 38 X-ray mask,
38a pattern on X-ray mask, 38b X-ray transmission area on X-ray mask,
39 silicon substrate, 40 semiconductor pattern, 41 X-ray
42a X-ray mask monitor wafer for stress measurement (wafer etched back),
42b X-ray mask monitor wafer for stress measurement with X-ray absorber film formed thereon
43a X-ray mask for manufacturing process (back-etched wafer)
43b X-ray mask for manufacturing process (back-etched wafer) with desired film formed in multiple layers
44a X-ray mask monitor wafer for stress measurement (back-etched wafer),
44b a stress measurement X-ray mask monitor wafer having a desired film formed in multiple layers,

Claims (14)

An X-ray mask manufacturing method for forming a pattern of the X-ray absorber using an etching mask and a resist disposed above the X-ray absorber, wherein the etching selectivity of the etching mask to the X-ray absorber is r, The thickness of the etching mask is de, the thickness of the X-ray absorber is dx, the pattern size of the required X-ray absorber is dl, and the required pattern accuracy of the X-ray absorber is a (%). Wherein an etching mask having a thickness de expressed by the following formula is used.
dx / r ≦ de ≦ dl × a / 100 2. The method for manufacturing an X-ray mask according to claim 1, wherein the shape of the etching mask patterned by etching is controlled to be isotropic. An X-ray absorber made of tungsten or a tungsten compound disposed above an etching stopper; an etching mask disposed above the X-ray absorber; and a resist disposed above the etching mask. In the X-ray mask on which a body pattern is formed, the etching stopper or the etching mask includes at least a layer made of platinum (Pt), a compound of platinum, a nitride of chromium, or a nitrided oxide of chromium. An X-ray mask comprising at least one layer. Etching is performed using an X-ray absorber placed above the etching stopper, an etching mask placed above the X-ray absorber, and a resist placed above the etching mask, An X-ray mask on which a pattern is formed , further comprising a secondary electron generation suppressing layer formed on the X-ray absorber on which the pattern is formed so as not to cover the entire X-ray absorber. X-ray mask. The X-ray mask according to claim 4, wherein the secondary electron generation suppressing layer contains carbon as a main component. The method for manufacturing an X-ray mask according to claim 5, wherein the X-ray absorber is etched with an etching gas to form a pattern, wherein the concentration of the carbon-containing gas is made higher than that at the time of etching to make carbon the main component. Forming the secondary electron generation suppressing layer by a step of forming a film to be formed. An X-ray absorber disposed above the etching stopper, an etching mask disposed above the X-ray absorber, and a resist disposed above the etching mask are used to form a pattern of the X-ray absorber. that the X-ray mask, X-rays mask it characterized in that a diffusion barrier layer on or between the etching mask and the X-ray absorber of the X-ray absorber and an etching stopper. The X-ray mask according to claim 7, wherein the diffusion suppressing layer is a surface oxide layer formed between the etching mask and the X-ray absorber. The X-ray mask according to claim 7, wherein the diffusion suppressing layer is a layer that is etched under an X-ray absorber etching condition. X-ray mask according to billed to claim 9 you, characterized in that the diffusion suppressing layer is etched at the etching conditions of the X-ray absorber made of tungsten or a tungsten compound containing silicon. An X-ray absorber arranged above the etching stopper, an etching mask arranged above the X-ray absorber, and a resist arranged above the etching mask are used to form the pattern of the X-ray absorber. that the X-ray mask, X-rays mask the surface roughness of the X-ray absorber, characterized in that at 0.05μm or less in _{R max.} The X-ray mask according to billed 7. The method of X-ray mask to and forming by performing patterning of the X-ray absorber by controlling an anisotropic etching and isotropic etching . The X-ray mask according to billed 7. The method of X-ray mask and forming by etching by vibrating the X-ray mask arranged downward the surface to be etched. An X-ray absorber is disposed above the X-ray transmission layer, and a pattern of the X-ray absorber is formed by using a resist disposed above an etching mask disposed above the X-ray absorber. A method of manufacturing an X-ray mask, wherein the etching is terminated according to light transmitted through the X-ray mask when etching the X-ray absorber.

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