JP4325192B2

JP4325192B2 - Halftone phase shift mask blank and halftone phase shift mask

Info

Publication number: JP4325192B2
Application number: JP2002376714A
Authority: JP
Inventors: 政秀岩片; 匡佐賀; 正松尾
Original assignee: Toppan Inc
Current assignee: Toppan Inc
Priority date: 2002-12-26
Filing date: 2002-12-26
Publication date: 2009-09-02
Anticipated expiration: 2022-12-26
Also published as: JP2004205921A

Description

【０００１】
【発明の属する技術分野】
本発明は半導体製造プロセス中のフォトリソグラフィ工程で使用される露光転写用のフォトマスク及びこれを製造するためのフォトマスクブランクに関わるものであり、特にマスクを通過する露光光間に位相差を与えることにより、転写パターンの解像度を向上させるようにしたハーフトーン型位相シフトマスク用ブランク及びハーフトーン型位相シフトマスクに関するものである。
【０００２】
【従来の技術】
半導体製造工程等においては、Ｓｉウェハー上などに微細パターンを形成するためのパターン露光用のマスクとしてフォトマスクが用いられる。このフォトマスクの一種に位相シフト法を用いた位相シフトマスクがある。位相シフト法は、微細パターンを転写する際の解像度向上技術の１つである。原理的にはマスク上の隣接する領域に互いの透過光の位相差が１８０度となるように位相シフト領域を設けることにより、透過光が回折し干渉し合う境界部の光強度を弱め、その結果として転写パターンの解像度を向上させるものである。これにより通常のフォトマスクに比べて飛躍的に優れた微細パターンの解像度向上効果および焦点深度向上の効果を有する。
【０００３】
上記位相シフトマスクの１種として、ハーフトーン型位相シフトマスクの開発が盛んに行われている。
ハーフトーン型位相シフトマスクは、透明基板上に形成するマスクパターンが実質的に露光に寄与する強度の光を透過させる透過部と、実質的に露光に寄与しない半透過部とで構成される。このとき透過光がダイレクトに透過する透過部に対して、半透過部には透過光の位相反転作用およびレジストの感度以下の光量を付与するための遮光性を持たせることにより、前記透過部と半透過部との境界部近傍を通過した光は互いに打ち消し合う。以上の原理から光強度のエッジ形状を急峻にし、解像性や焦点深度特性を向上させると共にマスクパターンを忠実にウエハ上に転写する効果を持つ。
【０００４】
また、近年では、ウエハ上に転写されるパターンの解像性をより高めるために、半透過部における光の透過率を高めた高透過率ハーフトーンマスクも提案されている（例えば、特許文献１参照）。高透過率ハーフトーンマスクは半透過部の透過率が高く、位相が反転して透過する光の強度も強くなる。このため位相の打ち消し効果が高くなり、Ｓｉウエハへのパターン転写時における解像性が向上する。このため目的に応じて、異なった透過率のマスク作製が求められている。
【０００５】
さらに、近年の半導体パターンの微細化に伴う露光波長の短波長化に対応するため、従来よりも短波長露光に対応したハーフトーンマスクが必要とされる。短波長化に対応するためには、半透過部の透過率を高くする必要があり、より透明性の高い材料を選定し、露光波長での位相差及び透過率を所望の条件にする必要がある。
【０００６】
半透過部の構成には、単層構造と多層構造の２種類がある。
単層構造の場合は１種類の物質で位相差、透過率の制御を行う。この場合、フォトマスクブランクスの膜組成自体を、求める位相差及び透過率を持ち合わせた物質に合わせ込んで、成膜を行う必要があり、成膜条件、フォトマスクブランクスの加工条件を所望の範囲に押さえ込むのは非常に難しい。
多層構造の場合は、２種類もしくはそれ以上の層から構成されており、各層の膜厚もしくは物性を変化させることによって、位相差、透過率の制御を行っている。しかし、多層構造の場合は各層で、膜厚、物性を制御しているため、単層の場合よりも位相差、透過率の光学特性及びフォトマスクブランクスの加工条件のバラツキ範囲が広がってしまうという問題を有している。
【０００７】
【特許文献１】
特開平０７−１５９９８１号公報
【０００８】
【発明が解決しようとする課題】
このように、ハーフトーン型位相シフトマスク用ブランクおよびマスクでは、位相差、透過率の光学特性の制御が必要である。
しかしながら、従来のマスク構成では、位相差、透過率の光学特性と、フォトマスクブランクスから高精度のパターンを得るための加工条件とを合わせ込むには、各シフタ層の作製毎に位相差、透過率の光学特性と加工条件を確認しなければならず、かなりの時間と労力を必要としている。
【０００９】
本発明は上記問題点に鑑み考案されたもので、位相差制御層及び透過率制御層からなるシフタ層の透過率制御層の屈折率を所望の値に制御することにより、位相差を変動させることなく透過率制御が容易なハーフトーン型位相シフトマスク用ブランク及びハーフトーン型位相シフトマスクを提供することを目的とする。
【００１０】
本発明では上記課題を解決するために、まず請求項１においては、透明基板上に露光光に対して位相及び透過率が制御された多層膜からなるシフタ層を設けたハーフトーン型位相シフトマスク用ブランクにおいて、前記シフタ層が、透過率制御層と位相制御層とで構成されており、前記透過率制御層の消衰係数k が2.0 ＜k で、かつ屈折率ｎが、0.8 ＜ｎ≦1.2 の条件を満たしており、前記透過率制御層および前記位相制御層は、Ｚｒ、Ｓｉの群から一つ以上の元素を含む化合物よりなることを特徴とするハーフトーン型位相シフトマスク用ブランクとしたものである。
【００１１】
これは、ハーフトーン型位相シフトマスク用ブランクのシフタ層を透過率制御層と位相差制御層の構成にし、透過率制御層の屈折率ｎを0.8＜ｎ≦1.2の範囲に設定することにより、位相差制御層の位相差特性に影響することなく、透過率制御層の膜厚を変えるだけで透過率を制御できる。このため加工条件を変える必要が無く、安定した高精度のハーフトーン型位相シフトマスクを得ることができる。
【００１２】
また、請求項２においては、透明基板上に露光光に対して位相及び透過率が制御された多層膜からなるシフタ層を設けたハーフトーン型位相シフトマスク用ブランクにおいて、前記シフタ層が、透過率制御層と位相制御層とで構成されており、前記透過率制御層の消衰係数k が1 ≦k ＜2 で、かつ屈折率ｎが、0.9 ＜ｎ≦1.1 の条件を満たしており、前記透過率制御層および前記位相制御層は、Ｚｒ、Ｓｉの群から一つ以上の元素を含む化合物よりなることを特徴とするハーフトーン型位相シフトマスク用ブランクとしたものである。
【００１３】
これは、ハーフトーン型位相シフトマスク用ブランクのシフタ層を透過率制御層と位相差制御層の構成にし、透過率制御層の屈折率ｎを0.9＜ｎ≦1.1の範囲に設定することにより、位相差制御層の位相差特性に影響することなく、透過率制御層の膜厚を変えるだけで透過率を制御できるため、加工条件を変える必要が無く、安定した高精度のハーフトーン型位相シフトマスクを得ることができる。
【００１４】
また、請求項３においては、請求項１または２に記載のハーフトーン型位相シフトマスク用ブランクを用いてパターニング処理し、露光光に対して透明な領域と位相シフト領域を形成したことを特徴とするハーフトーン型位相シフトマスクとしたものである。
【００１５】
【発明の実施の形態】
以下に本発明の実施の形態につき説明する。
図１（ａ）及び（ｂ）は、本発明のハーフトーン型位相シフトマスク用ブランクの構成の一例を示す模式構成断面図である。図２（ａ）及び（ｂ）は、本発明のハーフトーン型位相シフトマスクの構成の一例を示す模式構成断面図である。本発明のハーフトーン型位相シフトマスク用ブランクは図１（ａ）及び（ｂ）に示すように、透明基板１上に屈折率ｎが０．９＜ｎ≦１．１の条件を満たしている透過率制御層２と１８０度に位相制御された位相差制御層３とを形成してシフタ層４もしくはシフタ層４’を設けたものである。
ここで、透過率制御層２と位相差制御層３の成膜順序はどちらでも良く、成膜順序に合わせてシフタ層の光学特性の設計をすればよい。
【００１６】
上記透過率制御層２の屈折率ｎを０．９＜ｎ≦１．１の範囲に設定することにより、透過率制御層２の膜厚を変えて透過率を制御しても、シフタ層４の位相差はほとんど変化しない。
さらに、シフタ層４及びシフタ層４’の位相差制御層３は通常用いられているシフタ層がそのまま使用でき、所定の成膜条件、加工条件を確立すれば、透過率制御層２の膜厚を変化するだけで、シフタ層４及びシフタ層４’の位相差を変化することなく、透過率のみを変化させることができる。
ということは、本発明のハーフトーン型位相シフトマスク用ブランクでは、位相差制御層３を作製した後は透過率制御層２の膜厚を変化するだけで、シフタ層４の位相差を１８０±ｘ度に維持した状態で異なった透過率のハーフトーン型位相シフトマスク用ブランクを容易に作成することができる。ここで、許容範囲ｘは、位相シフトマスクの仕様によっても異なるが、通常は３である。
【００１７】
以下、位相差制御層３に対する透過率制御層２の膜厚依存性について説明する。図３〜図１２は、位相差制御層及び透過率制御層からなるシフタ層の位相差許容範囲を１８０±３度、透過率の設計値を３〜１５％とした場合、消衰係数ｋ＝０．１、屈折率ｎ＝２の所定膜厚の位相差制御層に対し、所定の消衰係数ｋ、屈折率ｎを有する透過率制御層を形成した場合の透過率制御層の膜厚に対するシフタ層の透過率変化及び位相差変化をシミュレーションしたものである。なお、殆どの透明膜は屈折率ｎ＝１.５〜２.５、消衰係数ｋ＝０〜０.２であり、計算には代表的なｎ＝２.０、ｋ＝０.１とした。遮光膜も同様、代表的な消衰係数である、ｋ＝１.０とｋ＝２.０の２種の膜に対して行った。
【００１８】
まず、消衰係数ｋ＝０．１、屈折率ｎ＝２.０、膜厚ｄ＝９６．５ｎｍからなる位相差制御層３に、消衰係数ｋ＝１．０、屈折率ｎ＝０．８の透過率制御層２を成膜してしてシフタ層４’を形成した場合シフタ層４’の透過率Ｔが３〜１５％を満たす透過率制御層２の膜厚ｄａと透過率Ｔの関係曲線を図３（ａ）に、シフタ層４’の位相差１８０±３度を満たす膜厚ｄａと位相差の関係曲線を図３（ｂ）に、それぞれ示す。
消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚ｄ＝９６．５ｎｍからなる位相差制御層３に、消衰係数ｋ＝１．０、屈折率ｎ＝０．８の透過率制御層２を成膜してシフタ層４’を形成した場合シフタ層４の透過率Ｔ（３〜１５％）を満たす透過率制御層２の膜厚ｄａは２３．０〜４７．５ｎｍとなり、この膜厚範囲ではシフタ層４’の位相差１８０±３度を満たすことができず、４０．０〜４７．５ｎｍの膜厚範囲でシフタ層４’の位相差は１８０±３度からずれた値となり、消衰係数ｋ＝１．０、屈折率ｎ＝０．８の透過率制御層の組み合わせでは透過率Ｔ（３〜１５％）、位相差１８０±３度を同時に満たすシフタ層を得ることはできない。
【００１９】
同様にして、位相差が１８０度に位相制御された消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚ｄ＝１００ｎｍからなる位相差制御層３に、消衰係数ｋ＝１．０、屈折率ｎ＝０．９の透過率制御層２を成膜してシフタ層４’を形成した場合シフタ層４’の透過率Ｔが３〜１５％を満たす透過率制御層２の膜厚ｄａと透過率Ｔの関係曲線を図４（ａ）に、シフタ層４の位相差１８０±３度を満たす膜厚ｄａと位相差の関係曲線を図４（ｂ）にそれぞれ示す。
シフタ層４’の透過率Ｔ（３〜１５％）を満たす透過率制御層２の膜厚ｄａは２４．０〜４６．０ｎｍとなり、この膜厚範囲ではシフタ層４’の位相差１８０±３度を同時に満たすことができる。
【００２０】
同様にして、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚ｄ＝９６．５ｎｍからなる位相差制御層３に、消衰係数ｋ＝１．０、屈折率ｎ＝１．０の透過率制御層２を成膜してシフタ層４’を形成した場合シフタ層４’の透過率Ｔが３〜１５％を満たす透過率制御層２の膜厚ｄａと透過率Ｔの関係曲線を図５（ａ）に、シフタ層４の位相差１８０±３度を満たす膜厚ｄａと位相差の関係曲線を図５（ｂ）にそれぞれ示す。
シフタ層４’の透過率Ｔ（３〜１５％）を満たす透過率制御層２の膜厚ｄａは２１．０〜４６．０ｎｍとなり、この膜厚範囲ではシフタ層４’の位相差１８０±３度を同時に満たすことができ、消衰係数ｋ＝１．０、屈折率ｎ＝１．０の透過率制御層との組み合わせでは透過率Ｔ（３〜１５％）、位相差１８０±３度を同時に満たすシフタ層を容易に得ることができる。
【００２１】
同様にして、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚ｄ＝９３．３ｎｍからなる位相差制御層３に、消衰係数ｋ＝１．０、屈折率ｎ＝１．１の透過率制御層２を成膜してシフタ層４’を形成した場合シフタ層４’の透過率Ｔが３〜１５％を満たす透過率制御層２の膜厚ｄａと透過率Ｔの関係曲線を図６（ａ）に、シフタ層４の位相差１８０±３度を満たす膜厚ｄａと位相差の関係曲線を図６（ｂ）にそれぞれ示す。
シフタ層４’の透過率Ｔ（３〜１５％）を満たす透過率制御層２の膜厚ｄａは１９．０〜４５．０ｎｍとなり、この膜厚範囲ではシフタ層４’の位相差１８０±３度を同時に満たすことができ、消衰係数ｋ＝１．０、屈折率ｎ＝１．０の透過率制御層との組み合わせでは透過率Ｔ（３〜１５％）、位相差１８０±３度を同時に満たすシフタ層を得ることができる。
【００２２】
同様にして、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚ｄ＝９１．１ｎｍからなる位相差制御層３に、消衰係数ｋ＝１．０、屈折率ｎ＝１．２の透過率制御層２を成膜してシフタ層４’を形成した場合シフタ層４’の透過率Ｔが３〜１５％を満たす透過率制御層２の膜厚ｄａと透過率Ｔの関係曲線を図７（ａ）に、シフタ層４’の位相差１８０±３度を満たす膜厚ｄａと位相差の関係曲線を図７（ｂ）にそれぞれ示す。
シフタ層４’の透過率Ｔ（３〜１５％）を満たす透過率制御層２の膜厚ｄａは１９．０〜４４．０ｎｍとなり、この膜厚範囲ではシフタ層４’の位相差１８０±３度を同時に満たすことができない。３５．０〜４４．０ｎｍの膜厚範囲でシフタ層４の位相差は１８０±３度からずれた値となり、消衰係数ｋ＝１．０、屈折率ｎ＝１．２の透過率制御層との組み合わせでは透過率Ｔ（３〜１５％）、位相差１８０±３度を同時に満たすシフタ層を得ることはできない。
【００２３】
同様にして、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚ｄ＝１０２ｎｍからなる位相差制御層３に、消衰係数ｋ＝２．０、屈折率ｎ＝０．７の透過率制御層２を成膜してシフタ層４’を形成した場合シフタ層４’の透過率Ｔが３〜１５％を満たす透過率制御層２の膜厚ｄａと透過率Ｔの関係曲線を図８（ａ）に、シフタ層４の位相差１８０±３度を満たす膜厚ｄａと位相差の関係曲線を図８（ｂ）にそれぞれ示す。
シフタ層４’の透過率Ｔ（３〜１５％）を満たす透過率制御層２の膜厚ｄａは１３．０〜２６．５ｎｍとなり、この膜厚範囲ではシフタ層４’の位相差１８０±３度を同時に満たすことができない。２４．０〜２６．５ｎｍの膜厚範囲でシフタ層４の位相差は１８０±３度からずれた値となり、消衰係数ｋ＝２．０、屈折率ｎ＝０．７の透過率制御層との組み合わせでは透過率Ｔ（３〜１５％）、位相差１８０±３度を同時に満たすシフタ層を得ることはできない。
【００２４】
同様にして、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚ｄ＝１００．３ｎｍからなる位相差制御層３に、消衰係数ｋ＝２．０、屈折率ｎ＝０．８の透過率制御層２を成膜してシフタ層４’を形成した場合シフタ層４’の透過率Ｔが３〜１５％を満たす透過率制御層２の膜厚ｄａと透過率Ｔの関係曲線を図９（ａ）に、シフタ層４’の位相差１８０±３度を満たす膜厚ｄａと位相差の関係曲線を図９（ｂ）にそれぞれ示す。
シフタ層４’の透過率Ｔ（３〜１５％）を満たす透過率制御層２の膜厚ｄａは１２．０〜２６．０ｎｍとなり、この膜厚範囲ではシフタ層４の位相差１８０±３度を同時に満たすことができ、消衰係数ｋ＝２．０、屈折率ｎ＝０．８の透過率制御層との組み合わせでは透過率Ｔ（３〜１５％）、位相差１８０±３度を同時に満たすシフタ層を得ることができる。
【００２５】
同様にして、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚ｄ＝９６．５ｎｍからなる位相差制御層３に、消衰係数ｋ＝２．０、屈折率ｎ＝１．０の透過率制御層２を成膜してシフタ層４’を形成した場合シフタ層４’の透過率Ｔが３〜１５％を満たす透過率制御層２の膜厚ｄａと透過率Ｔの関係曲線を図１０（ａ）に、シフタ層４’の位相差１８０±３度を満たす膜厚ｄａと位相差の関係曲線を図１０（ｂ）にそれぞれ示す。
シフタ層４’の透過率Ｔ（３〜１５％）を満たす透過率制御層２の膜厚ｄａは１０．５〜２４．０ｎｍとなり、この膜厚範囲ではシフタ層４’の位相差１８０±３度を同時に満たすことができ、消衰係数ｋ＝２．０、屈折率ｎ＝１．０の透過率制御層との組み合わせでは透過率Ｔ（３〜１５％）、位相差１８０±３度を同時に満たすシフタ層を得ることができる。
【００２６】
同様にして、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚ｄ＝９３．０ｎｍからなる位相差制御層３に、消衰係数ｋ＝２．０、屈折率ｎ＝１．２の透過率制御層２を成膜してシフタ層４’を形成した場合シフタ層４’の透過率Ｔが３〜１５％を満たす透過率制御層２の膜厚ｄａと透過率Ｔの関係曲線を図１１（ａ）に、シフタ層４’の位相差１８０±３度を満たす膜厚ｄａと位相差の関係曲線を図１１（ｂ）にそれぞれ示す。
シフタ層４’の透過率Ｔ（３〜１５％）を満たす透過率制御層２の膜厚ｄａは９．０〜２４．０ｎｍとなり、この膜厚範囲ではシフタ層４の位相差１８０±３度を同時に満たすことができ、消衰係数ｋ＝２．０、屈折率ｎ＝１．２の透過率制御層との組み合わせでは透過率Ｔ（３〜１５％）、位相差１８０±３度を同時に満たすシフタ層を得ることができる。
【００２７】
同様にして、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚ｄ＝９２．０ｎｍからなる位相差制御層３に、消衰係数ｋ＝２．０、屈折率ｎ＝１．３の透過率制御層２を成膜してシフタ層４’を形成した場合シフタ層４’の透過率Ｔが３〜１５％を満たす透過率制御層２の膜厚ｄａと透過率Ｔの関係曲線を図１２（ａ）に、シフタ層４の位相差１８０±３度を満たす膜厚ｄａと位相差の関係曲線を図１２（ｂ）にそれぞれ示す。
シフタ層４’の透過率Ｔ（３〜１５％）を満たす透過率制御層２の膜厚ｄａは９．０〜２３．０ｎｍとなり、この膜厚範囲ではシフタ層４の位相差１８０±３度を同時に満たすことができない。２０．５〜２３．０ｎｍの膜厚範囲でシフタ層４の位相差は１８０±３度からずれた値となり、消衰係数ｋ＝２．０、屈折率ｎ＝１．３の透過率制御層との組み合わせでは透過率Ｔ（３〜１５％）、位相差１８０±３度を同時に満たすシフタ層を得ることはできない。
【００２８】
以上の結果をまとめる。位相差が１８０度に位相制御され、且つ透明性の高い消衰係数ｋ＝０．１、屈折率ｎ＝２．０の所定膜厚の位相差制御層３に屈折率ｎの異なる透過率制御層２を成膜してシフタ層４を形成した場合、シフタ層４の透過率Ｔ（３〜１５％）と位相差１８０±３度を同時に満たす透過率制御層２の屈折率ｎは、消衰係数ｋ＝１.０の場合、０.９、１.０及び１．１である。また消衰係数ｋ＝２．０の場合０．８、１．０及び１．２となる。
つまり、透過率制御層２の消衰係数ｋが１.０≦ｋ＜２．０の範囲では屈折率ｎは０.９≦ｎ≦１．１、消衰係数ｋが２≦ｋでは屈折率ｎは０．８≦ｎ≦１．２の条件が満たされていれば、シフタ層４の透過率Ｔ（３〜１５％）、位相差１８０±３度を同時に満たす。
【００２９】
【実施例】
本発明のハーフトーン型位相シフトマスク用ブランク及びハーフトーン型位相シフトマスクの製造方法について説明する。
図１３（ａ）〜（ｄ）は、本発明のハーフトーン型位相シフトマスクの製造工程の一例を示す模式構成断面図である。
まず、ＺｒＳｉターゲット及びスパッターガスとしてアルゴン（Ａｒ）及び酸素（Ｏ₂）を用い、Ａｒ：７０ｓｃｃｍ、Ｏ₂：０．７ｓｃｃｍ、印加電力：２００Ｗのスパッタリング条件にて、石英基板からなる透明基板１上に屈折率ｎ＝１．０２、膜厚：１０ｎｍ、透過率：６％のジルコニウム−シリサイド化合物薄膜からなる透過率制御層２を形成した。
ここで、膜の位相差ＰＳは、ＰＳ＝３６０×（ｎ−１）×ｄ／λの一次式で近似することができる。ｎ：屈折率、ｄ：膜厚、λ：波長（１９３ｎｍ）である。上記屈折率１．０２、膜厚１０ｎｍの透過率制御層２で生ずる位相差は０．３７３度となる。さらに、上記のスパッタ条件で、スパッタ時間のみを変化させ、膜厚４４ｎｍで透過率約３％、膜厚２５ｎｍで透過率１５％のジルコニウム−シリサイド化合物薄膜を成膜した。透過率を３％から１５％変化しても位相差の変化は０．７１度であり、位相差はわずかしか変化しないことが確認された。
【００３０】
次に、ＺｒＳｉターゲット及びスパッターガスとしてアルゴン（Ａｒ）及び酸素（Ｏ₂）を用い、Ａｒ：７０ｓｃｃｍ、Ｏ₂：１０ｓｃｃｍ、印加電力：９００Ｗのスパッタリング条件にて、上記透過率制御層２上に消衰係数ｋが０．１以下の位相差１８０度、膜厚１００ｎｍのジルコニウム−シリサイド化合物薄膜からなる位相差制御層３を形成し、透明基板上１に透過率制御層２及び位相差制御層３からなるシフタ層４が形成されたハーフトーン型位相シフトマスク用ブランク１０を作製した（図１３（ａ）参照）。
【００３１】
次に、レジストを塗布し、感光層５を形成し、パターン露光、現像等の一連のパターニング処理を行って、レジストパターン５を形成する（図１３（ｂ）参照）。
【００３２】
次に、ハロゲンガス、例えばフロロカーボン系ガスをエッチングガスとして用いたドライエッチングにより、レジストパターン５をマスクとして位相差制御層３及び透過率制御層２エッチング除去し（図１３（ｃ）参照）、レジストパターン５をアッシング処理等により除去して、透過率制御パターン２ａ及び位相差制御パターン３ａからなるシフタパターン４ａを形成し、本発明のハーフトーン型位相シフトマスク１００を作製する（図１３（ｄ）参照）。
【００３３】
【発明の効果】
上記したように、本発明によれば、透過率制御層及び位相差制御層からなるシフタ層を有するハーフトーン型位相シフトマスク用ブランクにおいて、透過率制御層の屈折率ｎを、０．９≦ｎ≦１．１の範囲に設定することにより、透過率制御層の膜厚を設定するだけで、所望の透過率で１８０度の位相差を有するシフタ層からなるハーフトーン型位相シフトマスク用ブランクを容易に得ることができる。
また透過率制御層及び位相差制御層の成膜条件を固定できることから、加工条件を変化させることなく、シフタ層のパターン加工を行うことができ、高精度及び良好な形状を有するシフトパターンを有するハーフトーン型位相シフトマスクを容易に得ることができる。
【図面の簡単な説明】
【図１】（ａ）は、本発明のハーフトーン型位相シフトマスク用ブランクの一例を示す模式構成断面図である。
（ｂ）は、本発明のハーフトーン型位相シフトマスク用ブランクの他の例を示す模式構成断面図である。
【図２】（ａ）は、本発明のハーフトーン型位相シフトマスクの一例を示す模式構成断面図である。
（ｂ）は、本発明のハーフトーン型位相シフトマスクの他の例を示す模式構成断面図である。
【図３】（ａ）及び（ｂ）は、透過率制御層及び位相差制御層からなるシフタ層の位相差許容範囲を１８０±３度、透過率の設計値を３〜１５％とした場合の透過率制御層の膜厚に対するシフタ層の透過率変化及び位相差変化をシュミレーションした説明図であり、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚：９６．５ｎｍの位相差制御層と消衰係数ｋ＝１．０、屈折率ｎ＝０．８の透過率制御層の組み合わせの場合。
【図４】（ａ）及び（ｂ）は、透過率制御層及び位相差制御層からなるシフタ層の位相差許容範囲を１８０±３度、透過率の設計値を３〜１５％とした場合の透過率制御層の膜厚に対するシフタ層の透過率変化及び位相差変化をシュミレーションした説明図であり、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚：１００ｎｍの位相差制御層と消衰係数ｋ＝１．０、屈折率ｎ＝０．９の透過率制御層の組み合わせの場合。
【図５】（ａ）及び（ｂ）は、透過率制御層及び位相差制御層からなるシフタ層の位相差許容範囲を１８０±３度、透過率の設計値を３〜１５％とした場合の透過率制御層の膜厚に対するシフタ層の透過率変化及び位相差変化をシュミレーションした説明図であり、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚：９６．５ｎｍの位相差制御層と消衰係数ｋ＝１．０、屈折率ｎ＝１．０の透過率制御層の組み合わせの場合。
【図６】（ａ）及び（ｂ）は、透過率制御層及び位相差制御層からなるシフタ層の位相差許容範囲を１８０±３度、透過率の設計値を３〜１５％とした場合の透過率制御層の膜厚に対するシフタ層の透過率変化及び位相差変化をシュミレーションした説明図であり、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚：９３．３ｎｍの位相差制御層と消衰係数ｋ＝１．０、屈折率ｎ＝１．１の透過率制御層の組み合わせの場合。
【図７】（ａ）及び（ｂ）は、透過率制御層及び位相差制御層からなるシフタ層の位相差許容範囲を１８０±３度、透過率の設計値を３〜１５％とした場合の透過率制御層の膜厚に対するシフタ層の透過率変化及び位相差変化をシュミレーションした説明図であり、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚：９１．１ｎｍの位相差制御層と消衰係数ｋ＝１．０、屈折率ｎ＝１．２の透過率制御層の組み合わせの場合。
【図８】（ａ）及び（ｂ）は、透過率制御層及び位相差制御層からなるシフタ層の位相差許容範囲を１８０±３度、透過率の設計値を３〜１５％とした場合の透過率制御層の膜厚に対するシフタ層の透過率変化及び位相差変化をシュミレーションした説明図であり、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚：１０２ｎｍの位相差制御層と消衰係数ｋ＝２．０、屈折率ｎ＝０．７の透過率制御層の組み合わせの場合。
【図９】（ａ）及び（ｂ）は、透過率制御層及び位相差制御層からなるシフタ層の位相差許容範囲を１８０±３度、透過率の設計値を３〜１５％とした場合の透過率制御層の膜厚に対するシフタ層の透過率変化及び位相差変化をシュミレーションした説明図であり、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚：１００．３ｎｍの位相差制御層と消衰係数ｋ＝２．０、屈折率ｎ＝０．８の透過率制御層の組み合わせの場合。
【図１０】（ａ）及び（ｂ）は、透過率制御層及び位相差制御層からなるシフタ層の位相差許容範囲を１８０±３度、透過率の設計値を３〜１５％とした場合の透過率制御層の膜厚に対するシフタ層の透過率変化及び位相差変化をシュミレーションした説明図であり、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚：９６．５ｎｍの位相差制御層と消衰係数ｋ＝２．０、屈折率ｎ＝１．０の透過率制御層の組み合わせの場合。
【図１１】（ａ）及び（ｂ）は、透過率制御層及び位相差制御層からなるシフタ層の位相差許容範囲を１８０±３度、透過率の設計値を３〜１５％とした場合の透過率制御層の膜厚に対するシフタ層の透過率変化及び位相差変化をシュミレーションした説明図であり、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚：９３ｎｍの位相差制御層と消衰係数ｋ＝２．０、屈折率ｎ＝１．２の透過率制御層の組み合わせの場合。
【図１２】（ａ）及び（ｂ）は、透過率制御層及び位相差制御層からなるシフタ層の位相差許容範囲を１８０±３度、透過率の設計値を３〜１５％とした場合の透過率制御層の膜厚に対するシフタ層の透過率変化及び位相差変化をシュミレーションした説明図であり、消衰係数ｋ＝０．１、屈折率ｎ＝２．０、膜厚：９２ｎｍの位相差制御層と消衰係数ｋ＝２．０、屈折率ｎ＝１．３の透過率制御層の組み合わせの場合。
【図１３】（ａ）〜（ｄ）は、本発明のハーフトーン型位相シフトマスクの製造工程の一例を示す模式構成断面図でる。
【符号の説明】
１……透明基板
２……透過率制御層
２ａ……透過率制御パターン
３……位相差制御層
３ａ……位相差制御パターン
４、４’……シフタ層
４ａ、４’ａ……シフタパターン
１０、２０……ハーフトーン型位相シフトマスク用ブランク
１００、２００……ハーフトーン型位相シフトマスク[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photomask for exposure transfer used in a photolithography process in a semiconductor manufacturing process and a photomask blank for manufacturing the photomask, and in particular, provides a phase difference between exposure light passing through the mask. Thus, the present invention relates to a halftone phase shift mask blank and a halftone phase shift mask which improve the resolution of a transfer pattern.
[0002]
[Prior art]
In a semiconductor manufacturing process or the like, a photomask is used as a mask for pattern exposure for forming a fine pattern on a Si wafer or the like. One type of photomask is a phase shift mask using a phase shift method. The phase shift method is one of techniques for improving the resolution when transferring a fine pattern. In principle, by providing a phase shift region in the adjacent region on the mask so that the phase difference of the transmitted light is 180 degrees, the light intensity at the boundary where the transmitted light is diffracted and interferes is weakened. As a result, the resolution of the transfer pattern is improved. Thereby, it has the effect of improving the resolution and the depth of focus of a fine pattern which is remarkably superior to that of a normal photomask.
[0003]
As one type of the phase shift mask, a halftone type phase shift mask has been actively developed.
The halftone phase shift mask is composed of a transmissive part that transmits light having an intensity that contributes substantially to exposure by a mask pattern formed on a transparent substrate, and a semi-transmissive part that does not substantially contribute to exposure. At this time, with respect to the transmission part through which the transmitted light is directly transmitted, the semi-transmission part has a light-shielding property for imparting a light amount less than the phase inversion effect of the transmitted light and the sensitivity of the resist. The light that has passed through the vicinity of the boundary with the semi-transmissive portion cancels each other. From the above principle, the edge shape of the light intensity is sharpened, and the resolution and the depth of focus characteristics are improved and the mask pattern is faithfully transferred onto the wafer.
[0004]
In recent years, in order to further improve the resolution of a pattern transferred onto a wafer, a high-transmittance halftone mask in which the transmittance of light in a semi-transmissive part is increased has been proposed (for example, Patent Document 1). reference). The high-transmittance halftone mask has a high transmissivity in the semi-transmitting part, and the intensity of light that is transmitted with the phase reversed is also increased. For this reason, the phase canceling effect is enhanced, and the resolution at the time of pattern transfer to the Si wafer is improved. For this reason, masks having different transmittances are required depending on purposes.
[0005]
Furthermore, in order to cope with the shortening of the exposure wavelength accompanying the recent miniaturization of semiconductor patterns, a halftone mask corresponding to shorter wavelength exposure than before is required. In order to cope with shorter wavelengths, it is necessary to increase the transmissivity of the semi-transmission part, and it is necessary to select a material with higher transparency, and to set the phase difference and the transmissivity at the exposure wavelength to desired conditions. is there.
[0006]
There are two types of configurations of the semi-transmissive portion, a single layer structure and a multilayer structure.
In the case of a single layer structure, the phase difference and transmittance are controlled with one kind of substance. In this case, the film composition itself of the photomask blank needs to be combined with a substance having the required phase difference and transmittance to form a film, and the film formation conditions and the photomask blank processing conditions are within a desired range. It is very difficult to hold down.
In the case of a multilayer structure, it is composed of two or more types of layers, and the phase difference and transmittance are controlled by changing the film thickness or physical properties of each layer. However, in the case of a multilayer structure, the thickness and physical properties of each layer are controlled, so that the range of variations in retardation, transmittance optical characteristics, and photomask blank processing conditions is wider than in the case of a single layer. Have a problem.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 07-159981
[0008]
[Problems to be solved by the invention]
Thus, in the blank and mask for a halftone phase shift mask, it is necessary to control the optical characteristics of phase difference and transmittance.
However, in the conventional mask configuration, in order to combine the optical characteristics of the phase difference and transmittance with the processing conditions for obtaining a high-accuracy pattern from the photomask blank, the phase difference and transmission for each shifter layer are manufactured. The optical properties and processing conditions of the rate must be confirmed, which requires considerable time and effort.
[0009]
The present invention has been devised in view of the above problems, and the phase difference is varied by controlling the refractive index of the transmittance control layer of the shifter layer comprising the phase difference control layer and the transmittance control layer to a desired value. An object of the present invention is to provide a blank for a halftone phase shift mask and a halftone phase shift mask which can easily control transmittance.
[0010]
In the present invention, in order to solve the above problems, first, in claim 1, a halftone phase shift mask in which a shifter layer composed of a multilayer film whose phase and transmittance are controlled with respect to exposure light is provided on a transparent substrate. In the blank for use, the shifter layer is composed of a transmittance control layer and a phase control layer, the extinction coefficient k of the transmittance control layer is 2.0 <k, and the refractive index n is 0.8 <n ≦ Meets the requirements of 1.2, The transmittance control layer and the phase control layer are made of a compound containing one or more elements from the group of Zr and Si. A blank for a halftone phase shift mask characterized by the above.
[0011]
This is because the halftone phase shift mask blank shifter layer is composed of a transmittance control layer and a retardation control layer, and the refractive index n of the transmittance control layer is set in a range of 0.8 <n ≦ 1.2. The transmittance can be controlled only by changing the film thickness of the transmittance control layer without affecting the phase difference characteristics of the phase difference control layer. Therefore, there is no need to change the processing conditions, and a stable and highly accurate halftone phase shift mask can be obtained.
[0012]
According to a second aspect of the present invention, in the blank for a halftone type phase shift mask in which a shifter layer composed of a multilayer film whose phase and transmittance are controlled with respect to exposure light is provided on a transparent substrate, the shifter layer transmits An extinction coefficient k of the transmittance control layer is 1 ≦ k <2, and a refractive index n satisfies a condition of 0.9 <n ≦ 1.1. The transmittance control layer and the phase control layer are made of a compound containing one or more elements from the group of Zr and Si. A blank for a halftone phase shift mask characterized by the above.
[0013]
This is because the halftone phase shift mask blank shifter layer is configured as a transmittance control layer and a phase difference control layer, and the refractive index n of the transmittance control layer is set in a range of 0.9 <n ≦ 1.1. The transmittance can be controlled simply by changing the film thickness of the transmittance control layer without affecting the phase difference characteristics of the phase difference control layer, so there is no need to change the processing conditions and a stable and highly accurate halftone phase shift. A mask can be obtained.
[0014]
According to a third aspect of the present invention, there is provided a patterning process using the halftone phase shift mask blank according to the first or second aspect to form a transparent region and a phase shift region with respect to exposure light. This is a halftone phase shift mask.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
FIGS. 1A and 1B are schematic cross-sectional views showing an example of the configuration of a halftone phase shift mask blank of the present invention. 2A and 2B are schematic cross-sectional views showing an example of the configuration of the halftone phase shift mask of the present invention. As shown in FIGS. 1A and 1B, the halftone phase shift mask blank of the present invention satisfies the condition that the refractive index n is 0.9 <n ≦ 1.1 on the transparent substrate 1. The transmittance control layer 2 and the phase difference control layer 3 whose phase is controlled at 180 degrees are formed, and the shifter layer 4 or the shifter layer 4 ′ is provided.
Here, the film formation order of the transmittance control layer 2 and the phase difference control layer 3 may be either, and the optical characteristics of the shifter layer may be designed in accordance with the film formation order.
[0016]
Even if the transmittance is controlled by changing the film thickness of the transmittance control layer 2 by setting the refractive index n of the transmittance control layer 2 in the range of 0.9 <n ≦ 1.1, the shifter layer 4 There is almost no change in the phase difference.
Furthermore, as the phase difference control layer 3 of the shifter layer 4 and the shifter layer 4 ′, a commonly used shifter layer can be used as it is, and the film thickness of the transmittance control layer 2 can be established if predetermined film formation conditions and processing conditions are established. Only the transmittance can be changed without changing the phase difference between the shifter layer 4 and the shifter layer 4 ′.
That is, in the halftone phase shift mask blank of the present invention, after the phase difference control layer 3 is produced, the phase difference of the shifter layer 4 is changed by 180 ±± 0 by simply changing the film thickness of the transmittance control layer 2. Blanks for halftone phase shift masks having different transmittances can be easily produced while maintaining x degrees. Here, the allowable range x is usually 3 although it varies depending on the specifications of the phase shift mask.
[0017]
Hereinafter, the film thickness dependence of the transmittance control layer 2 with respect to the phase difference control layer 3 will be described. FIGS. 3 to 12 show an extinction coefficient k = when the allowable range of retardation of the shifter layer composed of the retardation control layer and the transmittance control layer is 180 ± 3 degrees and the design value of the transmittance is 3 to 15%. With respect to the thickness of the transmittance control layer when a transmittance control layer having a predetermined extinction coefficient k and a refractive index n is formed for a phase difference control layer having a predetermined thickness of 0.1 and a refractive index n = 2 This is a simulation of the transmittance change and the phase difference change of the shifter layer. Most of the transparent films have a refractive index n = 1.5 to 2.5 and an extinction coefficient k = 0 to 0.2. For calculation, typical n = 2.0 and k = 0.1. did. Similarly, the light shielding film was applied to two types of films having typical extinction coefficients of k = 1.0 and k = 2.0.
[0018]
First, the phase difference control layer 3 having an extinction coefficient k = 0.1, a refractive index n = 2.0, and a film thickness d = 96.5 nm has an extinction coefficient k = 1.0, a refractive index n = 0. When the shifter layer 4 ′ is formed by forming the transmittance control layer 2 of 8, the film thickness da and the transmittance T of the transmittance control layer 2 satisfying the transmittance T of 3 to 15% of the shifter layer 4 ′. FIG. 3 (a) shows the relationship curve, and FIG. 3 (b) shows the relationship curve between the film thickness da and the phase difference satisfying the phase difference of 180 ± 3 degrees of the shifter layer 4 ′.
The retardation control layer 3 having an extinction coefficient k = 0.1, a refractive index n = 2.0, and a film thickness d = 96.5 nm has an extinction coefficient k = 1.0 and a refractive index n = 0.8. When the transmittance control layer 2 is formed to form the shifter layer 4 ′, the film thickness da of the transmittance control layer 2 that satisfies the transmittance T (3 to 15%) of the shifter layer 4 is 23.0 to 47.5 nm. In this film thickness range, the phase difference 180 ± 3 degrees of the shifter layer 4 ′ cannot be satisfied, and the phase difference of the shifter layer 4 ′ from 180 ± 3 degrees in the film thickness range of 40.0 to 47.5 nm. Shifter layer that has a shifted value and satisfies the transmittance T (3 to 15%) and the phase difference of 180 ± 3 degrees in the combination of the transmittance control layer with the extinction coefficient k = 1.0 and the refractive index n = 0.8. Can't get.
[0019]
Similarly, the extinction coefficient k = 0.1, the refractive index n = 2.0, the film thickness d = 100 nm and the extinction coefficient k = 0.1 are controlled. When the shift control layer 2 having a refractive index n = 0.9 is formed to form the shifter layer 4 ′, the transmittance control layer 2 satisfying the transmittance T of the shifter layer 4 ′ of 3 to 15%. FIG. 4A shows a relationship curve between the film thickness da and the transmittance T, and FIG. 4B shows a relationship curve between the film thickness da and the phase difference satisfying the phase difference 180 ± 3 degrees of the shifter layer 4.
The film thickness da of the transmittance control layer 2 that satisfies the transmittance T (3 to 15%) of the shifter layer 4 ′ is 24.0 to 46.0 nm. In this film thickness range, the phase difference 180 ± 3 of the shifter layer 4 ′. The degree can be met at the same time.
[0020]
Similarly, the phase difference control layer 3 having an extinction coefficient k = 0.1, a refractive index n = 2.0, and a film thickness d = 96.5 nm is added to the extinction coefficient k = 1.0, the refractive index n = When the transmittance control layer 2 having a thickness of 1.0 is formed to form the shifter layer 4 ', the film thickness da and the transmittance T of the transmittance control layer 2 satisfying the transmittance T of 3 to 15%. FIG. 5A shows a relationship curve between the film thickness da and the phase difference satisfying the phase difference of 180 ± 3 degrees of the shifter layer 4, and FIG.
The film thickness da of the transmittance control layer 2 that satisfies the transmittance T (3 to 15%) of the shifter layer 4 ′ is 21.0 to 46.0 nm. In this film thickness range, the phase difference 180 ± 3 of the shifter layer 4 ′. In combination with a transmittance control layer having an extinction coefficient k = 1.0 and a refractive index n = 1.0, the transmittance T (3 to 15%) and the phase difference 180 ± 3 degrees can be satisfied. A shifter layer that fills at the same time can be easily obtained.
[0021]
Similarly, the extinction coefficient k = 0.1, the refractive index n = 2.0, the film thickness d = 93.3 nm, the retardation control layer 3 having the extinction coefficient k = 1.0, the refractive index n = When the shifter layer 4 ′ is formed by forming the transmittance control layer 2 of 1.1, the film thickness da and the transmittance T of the transmittance control layer 2 satisfying the transmittance T of 3 to 15% of the shifter layer 4 ′. FIG. 6A shows the relationship curve of FIG. 6A and FIG. 6B shows the relationship curve of the film thickness da and the phase difference satisfying the phase difference of 180 ± 3 degrees of the shifter layer 4.
The film thickness da of the transmittance control layer 2 that satisfies the transmittance T (3 to 15%) of the shifter layer 4 ′ is 19.0 to 45.0 nm. In this film thickness range, the phase difference 180 ± 3 of the shifter layer 4 ′. In combination with a transmittance control layer having an extinction coefficient k = 1.0 and a refractive index n = 1.0, the transmittance T (3 to 15%) and the phase difference 180 ± 3 degrees can be satisfied. A shifter layer that fills simultaneously can be obtained.
[0022]
Similarly, the extinction coefficient k = 0.1, the refractive index n = 2.0, the film thickness d = 91.1 nm, the retardation control layer 3 having the extinction coefficient k = 1.0, the refractive index n = When the transmittance control layer 2 having a thickness of 1.2 is formed to form the shifter layer 4 ′, the film thickness da and the transmittance T of the transmittance control layer 2 satisfying the transmittance T of 3 to 15% of the shifter layer 4 ′. FIG. 7A shows the relationship curve of FIG. 7A, and FIG. 7B shows the relationship curve of the film thickness da and the phase difference satisfying the phase difference of 180 ± 3 degrees of the shifter layer 4 ′.
The film thickness da of the transmittance control layer 2 that satisfies the transmittance T (3 to 15%) of the shifter layer 4 ′ is 19.0 to 44.0 nm. In this film thickness range, the phase difference 180 ± 3 of the shifter layer 4 ′. The degree cannot be met at the same time. In the thickness range of 35.0 to 44.0 nm, the phase difference of the shifter layer 4 is shifted from 180 ± 3 degrees, and the transmittance control layer has an extinction coefficient k = 1.0 and a refractive index n = 1.2. In combination, the shifter layer that simultaneously satisfies the transmittance T (3 to 15%) and the phase difference of 180 ± 3 degrees cannot be obtained.
[0023]
Similarly, the phase difference control layer 3 having an extinction coefficient k = 0.1, a refractive index n = 2.0, and a film thickness d = 102 nm is added to the extinction coefficient k = 2.0, the refractive index n = 0. 7 is formed to form the shifter layer 4 ′. The relationship between the film thickness da and the transmittance T of the transmittance control layer 2 in which the transmittance T of the shifter layer 4 ′ satisfies 3 to 15%. The curve is shown in FIG. 8A, and the relationship curve between the film thickness da and the phase difference satisfying the phase difference of 180 ± 3 degrees of the shifter layer 4 is shown in FIG. 8B.
The film thickness da of the transmittance control layer 2 that satisfies the transmittance T (3 to 15%) of the shifter layer 4 ′ is 13.0 to 26.5 nm. In this film thickness range, the phase difference 180 ± 3 of the shifter layer 4 ′. The degree cannot be met at the same time. In the thickness range of 24.0 to 26.5 nm, the phase difference of the shifter layer 4 is shifted from 180 ± 3 degrees, and the transmittance control layer has an extinction coefficient k = 2.0 and a refractive index n = 0.7. In combination, the shifter layer that simultaneously satisfies the transmittance T (3 to 15%) and the phase difference of 180 ± 3 degrees cannot be obtained.
[0024]
Similarly, the extinction coefficient k = 2.0, the refractive index n = 2.0, the film thickness d = 100.3 nm, the retardation control layer 3 having the extinction coefficient k = 2.0, the refractive index n = When the shifter layer 4 ′ is formed by forming the transmittance control layer 2 having a thickness of 0.8, the film thickness da and the transmittance T of the transmittance control layer 2 satisfying the transmittance T of 3 to 15% of the shifter layer 4 ′. FIG. 9A shows the relationship curve of FIG. 9A, and FIG. 9B shows the relationship curve of the film thickness da and the phase difference satisfying the phase difference of 180 ± 3 degrees of the shifter layer 4 ′.
The film thickness da of the transmittance control layer 2 that satisfies the transmittance T (3 to 15%) of the shifter layer 4 ′ is 12.0 to 26.0 nm, and the phase difference of the shifter layer 4 is 180 ± 3 degrees in this film thickness range. In combination with a transmittance control layer having an extinction coefficient k = 2.0 and a refractive index n = 0.8, a transmittance T (3 to 15%) and a phase difference of 180 ± 3 degrees are simultaneously satisfied. A filling shifter layer can be obtained.
[0025]
Similarly, an extinction coefficient k = 2.0, a refractive index n = 2.0, an extinction coefficient k = 0.1, a refractive index n = 2.0, and a retardation control layer 3 having a film thickness d = 96.5 nm. When the transmittance control layer 2 having a thickness of 1.0 is formed to form the shifter layer 4 ', the film thickness da and the transmittance T of the transmittance control layer 2 satisfying the transmittance T of 3 to 15%. FIG. 10 (a) shows the relationship curve, and FIG. 10 (b) shows the relationship curve between the film thickness da and the phase difference satisfying the phase difference 180 ± 3 degrees of the shifter layer 4 ′.
The film thickness da of the transmittance control layer 2 that satisfies the transmittance T (3 to 15%) of the shifter layer 4 ′ is 10.5 to 24.0 nm. In this film thickness range, the phase difference 180 ± 3 of the shifter layer 4 ′. In combination with a transmittance control layer having an extinction coefficient k = 2.0 and a refractive index n = 1.0, the transmittance T (3 to 15%) and the phase difference 180 ± 3 degrees can be satisfied. A shifter layer that fills simultaneously can be obtained.
[0026]
Similarly, the extinction coefficient k = 2.0, the refractive index n = 2.0, the film thickness d = 93.0 nm, the retardation control layer 3 having the extinction coefficient k = 2.0, the refractive index n = When the transmittance control layer 2 having a thickness of 1.2 is formed to form the shifter layer 4 ′, the film thickness da and the transmittance T of the transmittance control layer 2 satisfying the transmittance T of 3 to 15% of the shifter layer 4 ′. FIG. 11A shows the relationship curve of FIG. 11A, and FIG. 11B shows the relationship curve of the film thickness da and the phase difference satisfying the phase difference of 180 ± 3 degrees of the shifter layer 4 ′.
The film thickness da of the transmittance control layer 2 that satisfies the transmittance T (3 to 15%) of the shifter layer 4 ′ is 9.0 to 24.0 nm, and the phase difference of the shifter layer 4 is 180 ± 3 degrees in this film thickness range. In combination with a transmittance control layer having an extinction coefficient k = 2.0 and a refractive index n = 1.2, the transmittance T (3 to 15%) and the phase difference of 180 ± 3 degrees can be simultaneously satisfied. A filling shifter layer can be obtained.
[0027]
Similarly, an extinction coefficient k = 2.0, a refractive index n = 2.0, an extinction coefficient k = 2.0, a refractive index n = 2.0, and a film thickness d = 92.0 nm. When the shifter layer 4 ′ is formed by forming the transmittance control layer 2 having a thickness of 1.3, the film thickness da and the transmittance T of the transmittance control layer 2 satisfying the transmittance T of the shifter layer 4 ′ of 3 to 15%. FIG. 12A shows the relationship curve of FIG. 12 and FIG. 12B shows the relationship curve of the film thickness da and the phase difference satisfying the phase difference of 180 ± 3 degrees of the shifter layer 4.
The film thickness da of the transmittance control layer 2 that satisfies the transmittance T (3 to 15%) of the shifter layer 4 ′ is 9.0 to 23.0 nm. In this film thickness range, the phase difference of the shifter layer 4 is 180 ± 3 degrees. Cannot be satisfied at the same time. In the film thickness range of 20.5 to 23.0 nm, the phase difference of the shifter layer 4 is shifted from 180 ± 3 degrees, and the transmittance control layer has an extinction coefficient k = 2.0 and a refractive index n = 1.3. In combination, the shifter layer that simultaneously satisfies the transmittance T (3 to 15%) and the phase difference of 180 ± 3 degrees cannot be obtained.
[0028]
The above results are summarized. The phase difference is controlled to 180 degrees, and the transmittance control with a different refractive index n is applied to the phase difference control layer 3 having a predetermined thickness with a high extinction coefficient k = 0.1 and a refractive index n = 2.0. When the shifter layer 4 is formed by forming the layer 2, the refractive index n of the transmittance control layer 2 that simultaneously satisfies the transmittance T (3 to 15%) of the shifter layer 4 and the phase difference of 180 ± 3 degrees is When the attenuation coefficient k = 1.0, the values are 0.9, 1.0, and 1.1. When the extinction coefficient k = 2.0, the values are 0.8, 1.0, and 1.2.
That is, when the extinction coefficient k of the transmittance control layer 2 is 1.0 ≦ k <2.0, the refractive index n is 0.9 ≦ n ≦ 1.1, and when the extinction coefficient k is 2 ≦ k, the refractive index. If the condition of 0.8 ≦ n ≦ 1.2 is satisfied, n satisfies the transmittance T (3 to 15%) of the shifter layer 4 and the phase difference of 180 ± 3 degrees at the same time.
[0029]
【Example】
The blank for halftone phase shift mask and the method for producing the halftone phase shift mask of the present invention will be described.
FIGS. 13A to 13D are schematic cross-sectional views showing an example of the manufacturing process of the halftone phase shift mask of the present invention.
First, argon (Ar) and oxygen (O ₂ ), Ar: 70 sccm, O ₂ : On a transparent substrate 1 made of a quartz substrate under sputtering conditions of 0.7 sccm and applied power: 200 W, a zirconium-silicide compound thin film having a refractive index n = 1.02, a film thickness: 10 nm, and a transmittance: 6% A transmittance control layer 2 was formed.
Here, the phase difference PS of the film can be approximated by a linear expression of PS = 360 × (n−1) × d / λ. n: refractive index, d: film thickness, λ: wavelength (193 nm). The phase difference generated in the transmittance control layer 2 having a refractive index of 1.02 and a thickness of 10 nm is 0.373 degrees. Furthermore, only the sputtering time was changed under the above sputtering conditions, and a zirconium-silicide compound thin film having a transmittance of about 3% at a film thickness of 44 nm and a transmittance of 15% at a film thickness of 25 nm was formed. Even when the transmittance was changed from 3% to 15%, the change in phase difference was 0.71 degrees, and it was confirmed that the phase difference changed only slightly.
[0030]
Next, argon (Ar) and oxygen (O ₂ ), Ar: 70 sccm, O ₂ : Control of phase difference comprising a zirconium-silicide compound thin film having a phase difference of 180 degrees with an extinction coefficient k of 0.1 or less and a film thickness of 100 nm on the transmittance control layer 2 under sputtering conditions of 10 sccm and applied power of 900 W. A halftone phase shift mask blank 10 in which the layer 3 was formed and the shifter layer 4 composed of the transmittance control layer 2 and the phase difference control layer 3 was formed on the transparent substrate 1 was produced (see FIG. 13A). ).
[0031]
Next, a resist is applied to form a photosensitive layer 5, and a series of patterning processes such as pattern exposure and development are performed to form a resist pattern 5 (see FIG. 13B).
[0032]
Next, the phase difference control layer 3 and the transmittance control layer 2 are removed by etching using the resist pattern 5 as a mask by dry etching using a halogen gas, for example, a fluorocarbon-based gas as an etching gas (see FIG. 13C). The pattern 5 is removed by ashing or the like to form a shifter pattern 4a composed of the transmittance control pattern 2a and the phase difference control pattern 3a, and the halftone phase shift mask 100 of the present invention is manufactured (FIG. 13D). reference).
[0033]
【The invention's effect】
As described above, according to the present invention, in a blank for a halftone phase shift mask having a shifter layer composed of a transmittance control layer and a phase difference control layer, the refractive index n of the transmittance control layer is 0.9 ≦ By setting the film thickness of the transmittance control layer by setting it in the range of n ≦ 1.1, a blank for a halftone phase shift mask comprising a shifter layer having a phase difference of 180 degrees with a desired transmittance Can be easily obtained.
In addition, since the film formation conditions of the transmittance control layer and the retardation control layer can be fixed, the pattern processing of the shifter layer can be performed without changing the processing conditions, and the shift pattern has a high accuracy and a good shape. A halftone phase shift mask can be easily obtained.
[Brief description of the drawings]
FIG. 1A is a schematic sectional view showing an example of a blank for a halftone phase shift mask according to the present invention.
(B) is a schematic cross-sectional view showing another example of the blank for a halftone phase shift mask of the present invention.
FIG. 2A is a schematic sectional view showing an example of a halftone phase shift mask of the present invention.
(B) is a schematic cross-sectional view showing another example of the halftone phase shift mask of the present invention.
FIGS. 3A and 3B show the case where the allowable phase difference of the shifter layer composed of the transmittance control layer and the phase difference control layer is 180 ± 3 degrees, and the transmittance design value is 3 to 15%. It is explanatory drawing which simulated the transmittance | permeability change of the shifter layer with respect to the film thickness of the transmittance | permeability control layer, and the phase difference change, extinction coefficient k = 0.1, refractive index n = 2.0, film thickness: 96.5 nm. And a transmittance control layer having an extinction coefficient k = 1.0 and a refractive index n = 0.8.
FIGS. 4A and 4B show the case where the allowable phase difference of the shifter layer composed of the transmittance control layer and the phase difference control layer is 180 ± 3 degrees, and the transmittance design value is 3 to 15%. It is explanatory drawing which simulated the transmittance | permeability change of the shifter layer with respect to the film thickness of the transmittance | permeability control layer, and the phase difference change, extinction coefficient k = 0.1, refractive index n = 2.0, film thickness: about 100 nm. In the case of a combination of a phase difference control layer and a transmittance control layer having an extinction coefficient k = 1.0 and a refractive index n = 0.9.
FIGS. 5A and 5B show the case where the allowable phase difference of the shifter layer composed of the transmittance control layer and the phase difference control layer is 180 ± 3 degrees, and the transmittance design value is 3 to 15%. It is explanatory drawing which simulated the transmittance | permeability change of the shifter layer with respect to the film thickness of the transmittance | permeability control layer, and the phase difference change, extinction coefficient k = 0.1, refractive index n = 2.0, film thickness: 96.5 nm. And a transmittance control layer having an extinction coefficient k = 1.0 and a refractive index n = 1.0.
FIGS. 6A and 6B show the case where the allowable phase difference of the shifter layer composed of the transmittance control layer and the phase difference control layer is 180 ± 3 degrees, and the transmittance design value is 3 to 15%. It is explanatory drawing which simulated the transmittance | permeability change of the shifter layer with respect to the film thickness of the transmittance | permeability control layer, and the phase difference change, extinction coefficient k = 0.1, refractive index n = 2.0, film thickness: 93.3 nm. And a transmittance control layer having an extinction coefficient k = 1.0 and a refractive index n = 1.1.
FIGS. 7A and 7B show the case where the allowable phase difference of the shifter layer including the transmittance control layer and the phase difference control layer is 180 ± 3 degrees, and the transmittance design value is 3 to 15%. It is explanatory drawing which simulated the transmittance | permeability change of the shifter layer with respect to the film thickness of the transmittance | permeability control layer, and the phase difference change, extinction coefficient k = 0.1, refractive index n = 2.0, film thickness: 91.1 nm And a transmittance control layer having an extinction coefficient k = 1.0 and a refractive index n = 1.2.
FIGS. 8A and 8B show the case where the allowable phase difference of the shifter layer composed of the transmittance control layer and the phase difference control layer is 180 ± 3 degrees, and the transmittance design value is 3 to 15%. It is explanatory drawing which simulated the transmittance | permeability change of the shifter layer with respect to the film thickness of the transmittance | permeability control layer, and the phase difference change, extinction coefficient k = 0.1, refractive index n = 2.0, film thickness: about 102 nm In the case of a combination of a phase difference control layer and a transmittance control layer having an extinction coefficient k = 2.0 and a refractive index n = 0.7.
FIGS. 9A and 9B show the case where the allowable phase difference of the shifter layer composed of the transmittance control layer and the phase difference control layer is 180 ± 3 degrees, and the transmittance design value is 3 to 15%. It is explanatory drawing which simulated the transmittance | permeability change of the shifter layer with respect to the film thickness of the transmittance | permeability control layer, and the phase difference change, extinction coefficient k = 0.1, refractive index n = 2.0, film thickness: 100.3 nm And a transmittance control layer having an extinction coefficient k = 2.0 and a refractive index n = 0.8.
FIGS. 10A and 10B show the case where the allowable phase difference of the shifter layer including the transmittance control layer and the phase difference control layer is 180 ± 3 degrees, and the transmittance design value is 3 to 15%. It is explanatory drawing which simulated the transmittance | permeability change of the shifter layer with respect to the film thickness of the transmittance | permeability control layer, and the phase difference change, extinction coefficient k = 0.1, refractive index n = 2.0, film thickness: 96.5 nm. And a transmittance control layer having an extinction coefficient k = 2.0 and a refractive index n = 1.0.
FIGS. 11A and 11B show the case where the allowable phase difference of the shifter layer composed of the transmittance control layer and the phase difference control layer is 180 ± 3 degrees, and the transmittance design value is 3 to 15%. It is explanatory drawing which simulated the transmittance | permeability change of the shifter layer with respect to the film thickness of the transmittance | permeability control layer, and the phase difference change, extinction coefficient k = 0.1, refractive index n = 2.0, film thickness: about 93 nm In the case of a combination of a phase difference control layer and a transmittance control layer having an extinction coefficient k = 2.0 and a refractive index n = 1.2.
FIGS. 12A and 12B show the case where the allowable phase difference of the shifter layer composed of the transmittance control layer and the phase difference control layer is 180 ± 3 degrees, and the transmittance design value is 3 to 15%. It is explanatory drawing which simulated the transmittance | permeability change of the shifter layer with respect to the film thickness of the transmittance | permeability control layer, and the phase difference change, extinction coefficient k = 0.1, refractive index n = 2.0, film thickness: about 92 nm In the case of a combination of a phase difference control layer and a transmittance control layer having an extinction coefficient k = 2.0 and a refractive index n = 1.3.
FIGS. 13A to 13D are schematic sectional views showing an example of a manufacturing process of the halftone phase shift mask of the present invention.
[Explanation of symbols]
1 …… Transparent substrate
2. Transmission control layer
2a: Transmittance control pattern
3 …… Phase difference control layer
3a: Phase difference control pattern
4, 4 '…… Shifter layer
4a, 4'a ... Shifter pattern
10, 20 ... Blank for halftone phase shift mask
100, 200 …… Halftone phase shift mask

Claims

In a blank for a halftone phase shift mask provided with a shifter layer composed of a multilayer film whose phase and transmittance are controlled with respect to exposure light on a transparent substrate,
The shifter layer is composed of a transmittance control layer and a phase control layer,
The extinction coefficient k of the transmittance control layer is 2.0 <k, and the refractive index n satisfies a condition of 0.8 <n ≦ 1.2,
The blank for a halftone phase shift mask, wherein the transmittance control layer and the phase control layer are made of a compound containing one or more elements from the group of Zr and Si .

In a halftone phase shift mask blank in which a shifter layer composed of a multilayer film whose phase and transmittance are controlled with respect to exposure light is provided on a transparent substrate, the shifter layer includes a transmittance control layer, a phase control layer, and Consists of
The extinction coefficient k of the transmittance control layer satisfies 1 ≦ k <2 and the refractive index n satisfies the condition of 0.9 <n ≦ 1.1,
The blank for a halftone phase shift mask, wherein the transmittance control layer and the phase control layer are made of a compound containing one or more elements from the group of Zr and Si .

Patterning using the blank for halftone phase shift mask according to claim 1 or 2,
A halftone phase shift mask characterized by forming a transparent region and a phase shift region with respect to exposure light.