JP5744597B2 - Mask blank glass substrate manufacturing method, mask blank manufacturing method, transfer mask manufacturing method, and semiconductor device manufacturing method - Google Patents
Mask blank glass substrate manufacturing method, mask blank manufacturing method, transfer mask manufacturing method, and semiconductor device manufacturing method Download PDFInfo
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- 239000004065 semiconductor Substances 0.000 title claims description 22
- 238000005498 polishing Methods 0.000 claims description 221
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- 238000004140 cleaning Methods 0.000 claims description 73
- 238000000034 method Methods 0.000 claims description 48
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 38
- 239000008119 colloidal silica Substances 0.000 claims description 34
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- 238000011282 treatment Methods 0.000 claims description 20
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- FFBHFFJDDLITSX-UHFFFAOYSA-N benzyl N-[2-hydroxy-4-(3-oxomorpholin-4-yl)phenyl]carbamate Chemical compound OC1=C(NC(=O)OCC2=CC=CC=C2)C=CC(=C1)N1CCOCC1=O FFBHFFJDDLITSX-UHFFFAOYSA-N 0.000 description 1
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- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
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Landscapes
- Preparing Plates And Mask In Photomechanical Process (AREA)
Description
本発明は、基板表面に高さが数ｎｍ程度、大きさが５μｍ〜２０μｍ程度の凸状欠陥の発生を抑制するのに有効なマスクブランクス用ガラス基板の製造方法、マスクブランクスの製造方法、転写マスクの製造方法、及び半導体装置の製造方法等に関する。 INDUSTRIAL APPLICABILITY The present invention relates to a method for manufacturing a glass substrate for mask blanks, a method for manufacturing mask blanks, and a transfer method that are effective in suppressing the occurrence of convex defects having a height of about several nm and a size of about 5 μm to 20 μm The present invention relates to a mask manufacturing method, a semiconductor device manufacturing method, and the like.
近年における超ＬＳＩデバイスの高密度化、高精度化により、マスクブランクス用ガラス基板の平坦度や表面欠陥に対する要求は年々厳しくなる状況にある。ここで、従来のマスクブランクス用ガラス基板の表面粗さを低減するための精密研磨方法としては、例えば、特開平１−４０２６７号公報に記載されているものがある。この精密研磨方法は、酸化セリウムを主材とする研磨材を用いて研磨した後、コロイダルシリカを用いて仕上げ研磨するものである。この場合、上記公報によれば、一般的に市販されているコロイダルシリカは、安定性の点からｐＨが９〜１０．５の範囲にあるが、希釈して使う場合にはｐＨ値が低下するので、ＮａＯＨ、ＫＯＨ等の無機アルカリや、アミン等の有機アルカリを新たに添加し、ｐＨを〜１１と高めて使用する方がアルカリのガラスをエッチングする効果も相乗的に発揮されるので好ましいとされている。 The demand for flatness and surface defects of a glass substrate for mask blanks is becoming stricter year by year as the density and accuracy of VLSI devices in recent years increase. Here, as a precision polishing method for reducing the surface roughness of a conventional glass substrate for mask blanks, for example, there is one described in JP-A-1-40267. In this precision polishing method, polishing is performed using an abrasive mainly composed of cerium oxide, and then finish polishing is performed using colloidal silica. In this case, according to the above publication, the commercially available colloidal silica has a pH in the range of 9 to 10.5 from the viewpoint of stability, but the pH value decreases when used diluted. Therefore, it is preferable to add an inorganic alkali such as NaOH or KOH or an organic alkali such as amine and increase the pH to ˜11 because the effect of etching the alkali glass is also exhibited synergistically. Has been.
本願出願人は、上記コロイダルシリカを用いてｐＨを高めた状態で仕上げ研磨を行ったガラス基板の表面が、近年要求されている平坦度や表面欠陥に対する高いレベルの条件を満たすものであるか否かを克明に調査した。その結果、上記方法で仕上げ研磨を行ったガラス基板表面には、高さが数ｎｍ程度、大きさは数十ｎｍ〜２μｍの凸状の突起が形成されることがあることが判明した。これは、従来の目視検査では確認できない小さい高さ（数ｎｍ程度）の凸状の突起で、上記近年要請されるようになった高いレベルの表面欠陥フリーの要請を確認するために開発された欠陥検査装置によってはじめて確認することができたものである。 The applicant of the present application has determined whether or not the surface of a glass substrate that has been subjected to final polishing with the pH increased using the colloidal silica satisfies a high level requirement for flatness and surface defects that have recently been required. Katsuaki was investigated. As a result, it has been found that convex protrusions having a height of about several nanometers and a size of several tens of nanometers to 2 μm may be formed on the surface of the glass substrate that has been finish polished by the above method. This is a convex protrusion with a small height (several nanometers) that cannot be confirmed by conventional visual inspection, and was developed to confirm the above-mentioned requirement for a high level of surface defects that has recently been required. This can be confirmed for the first time by the defect inspection apparatus.
この高さが数ｎｍ程度の凸状の突起上に薄膜を形成し、マスクブランクス、転写マスクを作製した場合、高さが数ｎｍ程度の凸状の突起の大きさが拡大化されるため、次世代の基板として要求される０．３μｍ欠陥フリー（０．３μｍ以上の欠陥がないこと）、更には０．１μｍフリー（０．１μｍ以上の欠陥がないこと）、０．０５μｍ欠陥フリー（０．０５μｍ以上の欠陥がないこと）であったとしてもマスクブランクス、マスクの欠陥検査を行った場合、問題となることがある。 When a thin film is formed on a convex protrusion having a height of about several nm and a mask blank or a transfer mask is produced, the size of the convex protrusion having a height of about several nm is enlarged. 0.3 μm defect-free (no defects of 0.3 μm or more) required for next-generation substrates, 0.1 μm-free (no defects of 0.1 μm or more), 0.05 μm defect-free (0 Even if there is no defect of .05 μm or more), it may cause a problem when a defect inspection of mask blanks and masks is performed.
また、この高さが数ｎｍ程度の凸状の突起が形成されたガラス基板を使って位相シフトマスクブランクス、位相シフトマスクを作製した場合、露光光の波長が短波長になるにしたがって、高さが数ｎｍ程度の凸状の突起による位相角変化が大きくなり位相欠陥となる。この位相欠陥は、使用する露光波長が短くなるに従って、高さが数ｎｍ程度の凸状の突起による影響が大きくなり、特に、ＡｒＦエキシマレーザー、Ｆ２エキシマレーザー、ＥＵＶ光源を露光光源とする次世代のリソグラフィーにおいてその問題は顕著になる。例えば、凸状の突起の高さが５ｎｍの場合、露光波長がＡｒＦ（１９３ｎｍ）の場合、位相角変化は４．６度、Ｆ２（１５７ｎｍ）の場合、位相角変化は５．７度となり、また、この高さが数ｎｍ程度の凸状の突起が形成されたガラス基板を使ってＥＵＶ反射型マスクブランクス、ＥＵＶ反射型マスクを作成した場合、凸状の突起の高さが５ｎｍの場合、露光波長が１３．５ｎｍで２０度を超え、これらの位相角変化によって、ＣＤ誤差不良となり、無視できない問題となる。 In addition, when a phase shift mask blank and a phase shift mask are produced using a glass substrate on which convex protrusions having a height of about several nanometers are formed, the height of the exposure light becomes shorter as the wavelength becomes shorter. Becomes a phase defect due to a large change in the phase angle due to the convex protrusion of about several nm. This phase defect becomes more affected by convex protrusions having a height of about several nanometers as the exposure wavelength used becomes shorter. In particular, ArF excimer laser, F 2 excimer laser, and EUV light sources are used as exposure light sources. The problem becomes significant in next generation lithography. For example, when the height of the convex protrusion is 5 nm, when the exposure wavelength is ArF (193 nm), the phase angle change is 4.6 degrees, and when F 2 (157 nm), the phase angle change is 5.7 degrees. In addition, when EUV reflective mask blanks and EUV reflective masks are made using a glass substrate on which convex protrusions having a height of several nanometers are formed, the height of the convex protrusions is 5 nm. The exposure wavelength exceeds 20 degrees at 13.5 nm, and these phase angle changes cause a CD error failure, which cannot be ignored.
上記のように、コロイダルシリカを用いる超精密研磨後のガラス基板の主表面に、高さが数ｎｍ程度、大きさが数十ｎｍ〜２μｍの凸状の突起が発生することが確認されている。また、その発生原因として、コロイダルシリカ砥粒中に金属成分の不純物が混入していることが原因であることが本願出願人により解明されている。これは、基板主表面に金属成分を含んだゲル状のコロイダルシリカが付着し、それがマスクとなって、研磨レート差が生じ、凸状の突起が発生するというメカニズムであった。
この問題を解決するために、本願出願人は、有機ケイ素化合物を加水分解することで得られる高純度のコロイダルシリカを研磨砥粒に適用することなどを行い、改善を図る技術に関し先に出願を行っている（特許文献１）。
As described above, it has been confirmed that convex protrusions having a height of about several nanometers and a size of several tens of nanometers to 2 micrometers are generated on the main surface of the glass substrate after ultra-precision polishing using colloidal silica. . Further, it has been elucidated by the applicant of the present invention that the cause of the occurrence is that metal component impurities are mixed in the colloidal silica abrasive grains. This is a mechanism in which gel-like colloidal silica containing a metal component adheres to the main surface of the substrate, which serves as a mask, causes a difference in polishing rate, and generates convex protrusions.
In order to solve this problem, the applicant of the present application has first filed an application regarding a technique for improving by performing application of high purity colloidal silica obtained by hydrolyzing an organosilicon compound to abrasive grains. (Patent Document 1).
しかし、これらの対策を施しても、高さが数ｎｍ、大きさが１μｍ〜２０μｍ程度の巨大なシミ状の凸状欠陥（上述した「凸状の突起」と区別するため「凸状欠陥」と称する）の発生を抑制できない場合があった。
近年、研削工程、第１および第２研磨工程（粗研磨、精密研磨）を行った後、コロイダルシリカ砥粒とＮａＯＨ（基板をエッチングする効果を有する）を含有する研磨液を用いた超精密研磨工程（第３研磨工程）を行った後に、さらに研磨レ一トの低い（第３研磨工程の約１／１０程度）、コロイダルシリカ砥粒とＴＭＡＨ（テトラメチルアンモニア、基板をエッチングする効果が小さい）を含有する研磨液を用いた最終研磨工程（第４研磨工程）を行った高精度のガラス基板が製造され始めている。特に、この最終研磨工程で、本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥（巨大なシミ状の凸欠陥）が発生しており、問題となっていた。また、前記超精密研磨工程（第３研磨工程）が最終研磨工程である場合においても、本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥（巨大なシミ状の凸欠陥）が発生しており、問題となっていた。
However, even if these measures are taken, a huge spot-like convex defect having a height of several nm and a size of about 1 μm to 20 μm (the “convex defect” is distinguished from the above-mentioned “convex protrusion”). In some cases, it was not possible to suppress the occurrence of
In recent years, after performing a grinding process, first and second polishing processes (rough polishing, precision polishing), ultra-precision polishing using a polishing liquid containing colloidal silica abrasive grains and NaOH (having an effect of etching a substrate) After performing the step (third polishing step), the polishing rate is lower (about 1/10 of the third polishing step), and the effect of etching colloidal silica abrasive grains and TMAH (tetramethylammonia, substrate) is small. High-precision glass substrates that have undergone a final polishing step (fourth polishing step) using a polishing liquid containing) have begun to be manufactured. In particular, in this final polishing step, convex defects (giant spot-like convex defects) having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention occurred, which was a problem. . Further, even when the ultraprecision polishing step (third polishing step) is a final polishing step, the convex defect (giant spot shape) according to the present invention having a height of about several nm and a size of about 1 μm to 20 μm. Convex defect) has occurred, which is a problem.
本発明は、コロイダルシリカを用いた研磨砥粒による精密研磨を行っても、基板表面に本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥が発生しないか又は発生率の低いマスクブランクス用ガラス基板の製造方法、及び本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥に起因する位相欠陥のないマスクブランクスの製造方法を提供することを第一の目的とする。
また、本発明は、基板表面に本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥があることに起因するパターン欠陥のない転写マスクの製造方法、及び半導体装置の製造方法を提供することを第二の目的とする。
さらに、基板表面に本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥のないマスクブランクス用ガラス基板、及び本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥による位相欠陥のないマスクブランクス及び転写マスクを提供することを第三の目的とする。
In the present invention, even when precise polishing with abrasive grains using colloidal silica is performed, the above-mentioned convex defect having a height of about several nm and a size of about 1 μm to 20 μm does not occur on the substrate surface, or A method for manufacturing a glass substrate for a mask blank with a low incidence and a method for manufacturing a mask blank without a phase defect due to a convex defect having a height of about several nm and a size of about 1 μm to 20 μm according to the present invention are provided. The primary purpose is to do.
The present invention also provides a method for manufacturing a transfer mask free from pattern defects caused by the above-mentioned convex defects having a height of about several nanometers and a size of about 1 μm to 20 μm, and a semiconductor device. It is a second object to provide a manufacturing method.
Furthermore, the glass surface for mask blanks having no convex defect having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention on the substrate surface, and the height of about several nanometers and a size according to the present invention. It is a third object of the present invention to provide a mask blank and a transfer mask free from phase defects due to convex defects of about 1 μm to 20 μm.
本願発明者は、上記最終研磨工程（上記第４研磨工程、または上記第３研磨工程が最終研磨工程の場合もある）で、本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥が発生している現象およびその原因を克明に調べた。その結果、以下のことを解明した。
（１）上記特許文献１と同様に、研磨液中の不純物が原因であることが疑われる。たいていの異物等は研磨により除去されると考えられるため、原因究明は容易でない。
（２）つぎに、本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥（巨大なシミ状の凸欠陥）は、砥粒としてセリウム用いる第１および第２研磨工程（粗研磨、精密研磨）及びそれらの洗浄工程を経た段階でのガラス基板では発生していないことを確認した。第１および第２研磨工程（粗研磨、精密研磨）及びそれらの洗浄工程と、第３および第４研磨工程及びそれらの洗浄工程との違いは、（ｉ）砥粒としてセリウム用いるかコロイダルシリカを用いるか、（ｉｉ）取り代、（ｉｉｉ）アルカリ洗浄（非常に弱いエッチング作用あり）かフッ酸（弱いエッチング作用あり）洗浄か、である。
The inventor of the present application uses the final polishing step (the fourth polishing step or the third polishing step may be the final polishing step), and the height of the present invention is about several nm and the size is 1 μm to 20 μm. The phenomenon and the cause of the occurrence of a convex defect of a certain degree were investigated carefully. As a result, the following was clarified.
(1) Similar to Patent Document 1, it is suspected that the cause is an impurity in the polishing liquid. Since most foreign matters are considered to be removed by polishing, the cause investigation is not easy.
(2) Next, the convex defect having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention is a first and second polishing using cerium as abrasive grains. It was confirmed that it did not occur in the glass substrate after the steps (rough polishing, precision polishing) and those cleaning steps. The difference between the first and second polishing steps (rough polishing, precision polishing) and their cleaning steps, and the third and fourth polishing steps and their cleaning steps are as follows: (i) Use cerium as the abrasive grains or colloidal silica Or (iii) removal allowance, (iii) alkali cleaning (with very weak etching action) or hydrofluoric acid (with weak etching action) cleaning.
（３）本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥は、ＳＥＭ（走査型電子顕微鏡）で観察したところ、大きさが１μｍ〜２０μｍ程度の凸状欠陥（巨大なシミ状の凸欠陥）で、円形（楕円）タイプ（図２（１）参照）と不定形タイプ（図２（２）参照）の２種類に分類されることを解明した。
（４）つぎに、本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥（巨大なシミ状の凸欠陥）を分析したところ、ＴＥＭ−ＥＤＸ分析（透過型電子顕微鏡に付属するエネルギー分散型X線分光装置）では、界面及び特異元素は確認できないことから石英の段差であることを解明した。ＡＭＦ（原子間力顕微鏡）で分析したところ、高さは４ｎｍ程度であった。
ここで、EDX（エネルギー分散型X線分光法）は、電子線照射により発生する特性X線を検出し、エネルギーで分光することによって、元素分析や組成分析を行う手法である。多くの場合、SEM（走査型電子顕微鏡）またはTEM（透過型電子顕微鏡）に付属している。また、EDS： Energy Dispersive X-ray Spectroscopyとも呼ばれる。
(3) The convex defect having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention is observed by SEM (scanning electron microscope), and the size of the convex defect is about 1 μm to 20 μm. It has been elucidated that it is classified into two types, a circular (ellipse) type (see FIG. 2 (1)) and an indeterminate type (see FIG. 2 (2)).
(4) Next, when the convex defect having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention is analyzed, a TEM-EDX analysis (transmission electron) In the energy dispersive X-ray spectrometer attached to the microscope, the interface and singular elements cannot be confirmed. When analyzed by AMF (atomic force microscope), the height was about 4 nm.
Here, EDX (energy dispersive X-ray spectroscopy) is a technique for performing elemental analysis and composition analysis by detecting characteristic X-rays generated by electron beam irradiation and performing spectral analysis with energy. In many cases, it is attached to SEM (scanning electron microscope) or TEM (transmission electron microscope). Also called EDS: Energy Dispersive X-ray Spectroscopy.
（５）つぎに、本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥（巨大なシミ状の凸欠陥）における不定形タイプの凸欠陥を１つずつＳＥＭ観察で詳しく調べたところ、大腸菌、球菌、棹菌などを連想させる多様な形状のシミが多数確認されたことから、バクテリア、原生生物などの微生物が不定形シミの原因と推定した。
（６）砥粒としてコロイダルシリカを用いる第３および第４研磨工程（超精密研磨工程、最終（超精密）研磨工程）では、主表面が研磨された後のマスクブランク用基板は、フッ酸浸漬による洗浄（エッチング作用を伴う洗浄）が行われるが、処理待ちの基板は純水槽に浸漬した状態で、一時待機状態におかれる。
この第３研磨工程（超精密研磨工程）および第４研磨工程（最終（超精密）研磨工程）で、本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥（シミ状の凸欠陥）が発生することがわかった。
詳しくは、第３研磨工程（超精密研磨工程）または第４研磨工程（最終（超精密）研磨工程）が終了したガラス基板５〜１０枚をカセットに入れ、バンドシャワーをかけ、研磨工程に付随する純水槽に保管する。その後、カセットに入れたガラス基板を、基板搬送用の水槽（ため水のコンテナ）で搬送し、洗浄装置におけるローダー水槽（フッ酸洗浄前の保管水槽）にセットする。洗浄装置においては、ローダー水槽から、純水オバーフロー１分＋メガソニック、フッ酸＋ケイフッ酸＋メガソニック１分、フッ酸＋ケイフッ酸＋メガソニック１分、純水スクラブ洗浄、純水オバーフロー＋メガソニック、スピンすすぎ、スピン乾燥で処理する。以上の工程で本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥（シミ状の凸欠陥）が発生することがわかった。
基板搬送用の水槽（ため水のコンテナ）、洗浄装置におけるローダー水槽、等の純水（ＤＩＷ）採取し、生菌培養キットで培養したところ多数のバクテリアが確認され、ＳＥＭ観察（２万倍）した結果、大腸菌を確認した。
つぎに、基板搬送用のため水コンテナ、洗浄装置におけるローダー水槽、等の生菌数と、シミ状の凸欠陥発生との因果関係について、加速試験にて、検証した。加速試験は、多数のバクテリアが確認された、基板搬送用の水槽（ため水のコンテナ）および洗浄装置におけるローダー水槽にそれぞれ保管（浸漬）されたガラス基板（５〜１０枚をカセット）を、それぞれ、フッ酸（濃度０．２ｗｔ％）に６００秒浸漬して実施した。その結果、基板搬送用のため水コンテナ、フッ酸処理前のローダー水槽、等に生菌が多く含まれる場合に、本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥（シミ状の凸欠陥）が発生することがわかった。
(5) Next, SEM observation is performed one by one on the irregular type convex defect in the convex defect (giant spot-like convex defect) having a height of about several nm and a size of about 1 μm to 20 μm according to the present invention. When we examined in detail, we found many stains of various shapes reminiscent of E. coli, cocci, and koji molds, so we estimated that microorganisms such as bacteria and protists were the cause of irregular stains.
(6) In the third and fourth polishing steps (ultra-precision polishing step, final (ultra-precision) polishing step) using colloidal silica as the abrasive grains, the mask blank substrate after the main surface is polished is immersed in hydrofluoric acid The substrate waiting for processing is immersed in a pure water bath and placed in a temporary standby state.
In the third polishing step (ultra-precision polishing step) and the fourth polishing step (final (ultra-precision) polishing step), a convex defect (about several nanometers in height and about 1 μm to 20 μm in size) according to the present invention ( It was found that a spot-like convex defect) occurred.
Specifically, 5-10 glass substrates that have finished the third polishing process (ultra-precision polishing process) or the fourth polishing process (final (ultra-precision) polishing process) are put in a cassette, and a band shower is applied to the polishing process. Store in a pure water tank. Thereafter, the glass substrate placed in the cassette is transported in a water tank for transporting the substrate (container for irrigation water) and set in a loader water tank (storage tank before hydrofluoric acid cleaning) in the cleaning device. In the cleaning device, pure water overflow 1 minute + megasonic, hydrofluoric acid + silicic acid + megasonic 1 minute, hydrofluoric acid + silicic acid + megasonic 1 minute, pure water scrub cleaning, pure water overflow + mega Process by sonic, spin rinse, spin dry. It has been found that the above-described steps generate convex defects (spot-shaped convex defects) having a height of about several nm and a size of about 1 μm to 20 μm.
When collecting pure water (DIW) such as a water tank for transporting substrates (container for irrigation water), a loader water tank in a cleaning device, etc., and cultivating with a viable cell culture kit, many bacteria are confirmed and SEM observation (20,000 times) As a result, E. coli was confirmed.
Next, the causal relationship between the number of viable bacteria in the water container for loading the substrate, the loader water tank in the cleaning device, etc. and the occurrence of a spot-like convex defect was verified by an acceleration test. In the accelerated test, glass substrates (5 to 10 cassettes) stored (immersed) in a water tank for transporting substrates (container for irrigation water) and a loader water tank in a cleaning device, respectively, in which a large number of bacteria have been confirmed, The sample was immersed in hydrofluoric acid (concentration: 0.2 wt%) for 600 seconds. As a result, when a lot of viable bacteria are contained in a water container, a loader water tank before hydrofluoric acid treatment, etc. for substrate transfer, the height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention. It has been found that a spot-like defect (spot-like convex defect) occurs.
（７）上記のことから、以下のことがわかった。
洗浄装置におけるローダー水槽内の純水は、循環ろ過されているが、純水製造装置からの配管距離が長いこと、ローダー水槽内の純水を循環ろ過するための配管内は殺菌洗浄されていなかったこと、また、研磨が終了したガラス基板には作業者の皮膚接触と環境からのバクテリア持ち込み、などが原因で、バクテリアが発生増加していた。このため、ローダー水槽内のバクテリアが、基板表面に付着して繁殖してしまう場合があることを解明した。そして、バクテリアが付着した基板が保管水槽から取り出され、フッ酸槽に浸漬された場合、基板主表面のフッ酸洗浄（エッチング）において、バクテリアがマスクとなってしまい、基板主表面に本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥（シミ状の凸欠陥）が発生することを解明した。基板搬送用のため水コンテナにおいて、バクテリアが基板表面に付着して繁殖してしまう場合についても同様である。
(7) From the above, the following was found.
The pure water in the loader water tank in the cleaning device is circulated and filtered, but the piping distance from the pure water production device is long, and the pipe for circulating and filtering the pure water in the loader water tank is not sterilized and washed. In addition, the generation of bacteria increased due to the contact of the skin of the worker and the introduction of bacteria from the environment on the polished glass substrate. For this reason, it was clarified that the bacteria in the loader water tank may adhere to the substrate surface and propagate. When the substrate with bacteria attached is taken out of the storage water tank and immersed in the hydrofluoric acid tank, the bacteria become a mask in the hydrofluoric acid cleaning (etching) of the main surface of the substrate, and the main surface of the substrate is applied to the present invention. It has been clarified that a convex defect (spot-shaped convex defect) having a height of about several nanometers and a size of about 1 μm to 20 μm occurs. The same applies to the case where bacteria adhere to the substrate surface and propagate in the water container for substrate transport.
（８）本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥（シミ状の凸欠陥）は、砥粒としてセリウム用いる第１および第２研磨工程（粗研磨、精密研磨）及びそれらの洗浄工程（アルカリ洗浄を含む）を経たガラス基板では発生しない。この理由は以下のように考えられる。
１）バクテリアは酸性でガラス基板表面につきやすく（基板表面はＳｉ−ＯＨで、ＣＯＯ−等のマイナス電荷とＮＨ３＋等のプラス電荷により等電位となったバクテリアとの間で反発作用は弱まるため）。
２）中性・アルカリ性ではガラス基板表面につきにくい（基板表面はＳｉ−Ｏ−で、ＣＯＯ−等を有するバクテリアとの間でマイナス電荷同士の反発作用があるため。
３）バクテリア（タンパク質）はフッ酸で侵されないため。
(8) The convex defects (spot-shaped convex defects) having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention are first and second polishing steps (rough polishing, It does not occur in glass substrates that have undergone precision polishing and their cleaning steps (including alkali cleaning). The reason is considered as follows.
1) Bacteria are acidic and easy to touch the glass substrate surface (because the substrate surface is Si—OH, and the repulsive action is weakened between bacteria with a negative charge such as COO − and an equipotential due to a positive charge such as NH 3+ ) .
2) The glass substrate surface is difficult to be neutral / alkaline (because the substrate surface is Si—O − , and there is a repulsive action between negative charges with bacteria having COO − or the like.
3) Because bacteria (protein) are not attacked by hydrofluoric acid.
（９）最終研磨工程が、第３研磨工程およびフッ酸処理の場合と、第４研磨工程およびフッ酸処理の場合とで比較した。その結果、第３研磨工程およびフッ酸処理の場合、第４研磨工程およびフッ酸処理の場合と比べ、本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥の発生率に目立った相違はないことがわかった。
なお、本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥（シミ状の凸欠陥）は、第３研磨工程およびフッ酸処理において発生しても、第４研磨工程である程度除去できるので、第３研磨工程（超精密研磨工程）に続いて第４研磨工程（最終超精密研磨工程）が実施される場合においては、第４研磨工程後およびフッ酸処理に対して、本発明に係る対策を実施することが好ましい。
第３研磨工程（超精密研磨工程）が、最終磨工程である場合においては、第３研磨工程後およびフッ酸処理に対して、本発明に係る対策を実施することが好ましい。
(9) The final polishing step was compared between the third polishing step and hydrofluoric acid treatment, and the fourth polishing step and hydrofluoric acid treatment. As a result, in the case of the third polishing step and hydrofluoric acid treatment, compared to the case of the fourth polishing step and hydrofluoric acid treatment, the height defect of about several nm and the size of the convex defect of about 1 μm to 20 μm according to the present invention. It was found that there was no noticeable difference in the incidence.
Note that the convex defect (spot-shaped convex defect) having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention may occur in the third polishing step and the hydrofluoric acid treatment, even if it occurs in the fourth polishing step. Since it can be removed to some extent in the process, when the fourth polishing process (final ultraprecision polishing process) is carried out following the third polishing process (ultraprecision polishing process), after the fourth polishing process and for hydrofluoric acid treatment Therefore, it is preferable to implement the measures according to the present invention.
When the third polishing step (ultra-precision polishing step) is the final polishing step, it is preferable to implement the measures according to the present invention after the third polishing step and for the hydrofluoric acid treatment.
（１０）本発明者は、以下の対策では不都合があることを解明した。
１）バクテリア等の発生を抑制するため、塩素、殺菌剤などを使用する対策は、それらが付着した基板をフッ酸等で洗浄したときに化学反応を起こす恐れがあるため不可である。
２）最終研磨工程後のフッ酸処理なくすと本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥は発生しないが、しかしコロイダルシリカを除去できなくなる。
(10) The inventor has clarified that the following measures are inconvenient.
1) In order to suppress the generation of bacteria and the like, measures using chlorine, bactericides, etc. are not possible because a chemical reaction may occur when the substrate to which they are attached is washed with hydrofluoric acid or the like.
2) If the hydrofluoric acid treatment after the final polishing step is eliminated, the convex defect having the height of about several nm and the size of about 1 μm to 20 μm according to the present invention does not occur, but the colloidal silica cannot be removed.
本発明は、以下の構成を有する。
（構成１）
マスクブランクス用ガラス基板表面を、研磨砥粒を含む研磨液を用いて両面研磨する研磨工程を有するマスクブランクス用ガラス基板の製造方法において、
前記研磨後の基板を、フッ酸、ケイフッ酸、またはフッ酸及びケイフッ酸を含む洗浄液で処理する洗浄工程を有すると共に、
前記洗浄工程を行う前の基板を保管しておく純水槽内、または前記純水槽の純水循環経路に、紫外線を照射する手段を有する、
ことを特徴とするマスクブランクス用ガラス基板の製造方法。
（構成２）
前記紫外線を照射する手段は、水銀ランプであることを特徴とする構成１に記載のマスクブランクス用ガラス基板の製造方法。
（構成３）
前記純水槽の純水循環経路に、フィルタ手段を有することを特徴とする構成１または２に記載のマスクブランクス用ガラス基板の製造方法。
（構成４）
前記洗浄工程を行う前の基板を保管しておく純水槽と、前記洗浄工程を行う洗浄槽との間に、純水処理と、超音波またはメガソニック処理とを組み合わせた処理を行う工程を設けることを特徴とする構成１〜３のいずれかに記載のマスクブランクス用ガラス基板の製造方法。
（構成５）
前記研磨砥粒は、コロイダルシリカ砥粒を含むことを特徴とする構成１〜４のいずれかに記載のマスクブランクス用ガラス基板の製造方法。
（構成６）
前記研磨液のｐＨが、９．６〜１１．０であることを特徴とする構成１〜５のいずれかに記載のマスクブランクス用ガラス基板の製造方法。
（構成７）
構成１〜６のいずれかに記載のマスクブランクス用ガラス基板の製造方法で製造したマスクブランク用ガラス基板の主表面上に、露光光に対し光学的変化をもたらす薄膜を形成することを特徴とするマスクブランクスの製造方法。
（構成８）
構成７に記載のマスクブランクスの製造方法で製造したマスクブランクスにおける前記薄膜をパターニングして、前記ガラス基板上に薄膜パターンを形成することを特徴とする転写マスクの製造方法。
（構成９）
構成８に記載の転写マスクの製造方法で製造した転写マスクを用いて、半導体基板上にリソグラフィー技術により微細パターンを形成することを特徴とする半導体装置の製造方法。
The present invention has the following configuration.
(Configuration 1)
In the manufacturing method of the glass substrate for mask blanks, which has a polishing step of double-side polishing the glass substrate surface for mask blanks using a polishing liquid containing polishing abrasive grains,
And having a cleaning step of treating the polished substrate with hydrofluoric acid, silicic hydrofluoric acid, or a cleaning liquid containing hydrofluoric acid and silicic hydrofluoric acid,
In the pure water tank for storing the substrate before performing the cleaning step, or having a means for irradiating ultraviolet light to the pure water circulation path of the pure water tank,
The manufacturing method of the glass substrate for mask blanks characterized by the above-mentioned.
(Configuration 2)
The method for producing a glass substrate for mask blanks according to Configuration 1, wherein the means for irradiating ultraviolet rays is a mercury lamp.
(Configuration 3)
The method for producing a glass substrate for mask blanks according to Configuration 1 or 2, wherein a filter means is provided in a pure water circulation path of the pure water tank.
(Configuration 4)
Between the pure water tank for storing the substrate before the cleaning process and the cleaning tank for performing the cleaning process, a process of performing a process combining pure water treatment and ultrasonic or megasonic treatment is provided. The manufacturing method of the glass substrate for mask blanks in any one of the structures 1-3 characterized by the above-mentioned.
(Configuration 5)
The said abrasive grain contains a colloidal silica abrasive grain, The manufacturing method of the glass substrate for mask blanks in any one of the structures 1-4 characterized by the above-mentioned.
(Configuration 6)
PH of the said polishing liquid is 9.6-11.0, The manufacturing method of the glass substrate for mask blanks in any one of the structures 1-5 characterized by the above-mentioned.
(Configuration 7)
A thin film that causes an optical change with respect to exposure light is formed on the main surface of the glass substrate for mask blanks manufactured by the method for manufacturing a glass substrate for mask blanks according to any one of configurations 1 to 6. Manufacturing method of mask blanks.
(Configuration 8)
A method for producing a transfer mask, comprising: patterning the thin film in a mask blank produced by the method for producing a mask blank described in Structure 7 to form a thin film pattern on the glass substrate.
(Configuration 9)
A method for manufacturing a semiconductor device, wherein a fine pattern is formed on a semiconductor substrate by a lithography technique using the transfer mask manufactured by the method for manufacturing a transfer mask according to Configuration 8.
本発明によれば、コロイダルシリカを用いた研磨砥粒による精密研磨を行っても、基板表面に本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥が発生しないマスクブランクス用ガラス基板及びその製造方法を提供することができる。また、基板表面に本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥のないマスクブランクス用ガラス基板を使用してマスクブランクスを作製することにより、位相欠陥のないマスクブランクス及びその製造方法を提供することができる。位相欠陥のないマスクブランクスを使用して転写マスクを作製することによりパターン欠陥のない転写マスクを製造することができる。さらに、パターン欠陥のない転写マスクを使用してリソグラフィー技術により半導体基板上に微細パターンを形成するので、パターン欠陥のない半導体装置を製造することができる。
特に、本発明は、高さ数ｎｍレベルの凸状欠陥でも位相欠陥を生じてしまうような位相シフトマスク用のガラス基板の製造に有効である。また、高さ数十ｍｎレベノレの凸状欠陥でもその上に多層反射膜が形成されたときにＥＵＶ露光光に対する反射率が低下してしまうような反射型マスクブランク用の基板の製造にも有効である。
According to the present invention, even when precise polishing is performed with abrasive grains using colloidal silica, the above-described convex defect having a height of about several nanometers and a size of about 1 μm to 20 μm does not occur on the substrate surface. A glass substrate for mask blanks and a method for producing the same can be provided. Moreover, there is no phase defect by producing mask blanks using a glass substrate for mask blanks having no convex defects having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention on the substrate surface. A mask blank and a manufacturing method thereof can be provided. A transfer mask having no pattern defect can be manufactured by producing a transfer mask using a mask blank having no phase defect. Furthermore, since a fine pattern is formed on the semiconductor substrate by lithography using a transfer mask having no pattern defect, a semiconductor device having no pattern defect can be manufactured.
In particular, the present invention is effective in manufacturing a glass substrate for a phase shift mask that causes phase defects even with convex defects having a height of several nanometers. It is also effective for the production of a substrate for a reflective mask blank in which the reflectance with respect to EUV exposure light is lowered even when a convex defect having a height of several tens of mn is formed on a multilayer reflective film. It is.
以下、本発明を詳細に説明する。
本発明のマスクブランクス用ガラス基板の製造方法は、マスクブランクス用ガラス基板表面を、研磨砥粒を含む研磨液を用いて両面研磨する研磨工程を有するマスクブランクス用ガラス基板の製造方法において、
前記研磨後の基板を、フッ酸、ケイフッ酸、またはフッ酸及びケイフッ酸を含む洗浄液で処理する洗浄工程を有すると共に、
前記洗浄工程を行う前の基板を保管しておく純水槽内、または前記純水槽の純水循環経路に、紫外線を照射する手段を有する、
ことを特徴とする。
上記構成によれば、バクテリア等が原因と考えられる本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥が発生しないか、発生率を低減できる。
本発明において、前記洗浄工程を行う前の基板を保管しておく純水槽としては、研磨工程に付随する純水槽（研磨後の基板を保管しておく純水槽）、基板搬送用の水槽（ため水のコンテナ）、洗浄装置におけるフッ酸処理前のローダー水槽、などが挙げられる。
本発明においては、基板にバクテリア等が付着していない状態で、基板をフッ酸、ケイフッ酸、またはフッ酸及びケイフッ酸を含む洗浄液で処理することが好ましい。
このためには、バクテリア等の無い状態（環境下）で基板を保管することが好ましい。例えば、研磨工程に付随する純水槽（研磨後の基板を保管しておく純水槽）、基板搬送用の水槽（ため水のコンテナ）、洗浄装置におけるフッ酸処理前のローダー水槽、などに純水製造装置から新しい（未使用の）純水を供給する手法や、これらの槽でバクテリア等が発生しない手段を講じる手法などが挙げられる。
また、フッ酸（エッチング）処理前に、基板にバクテリア等が付着していない状態にすることも効果的である。例えば、フッ酸（エッチング）処理前に、スクラブ処理、超音波・メガソニック処理、ＵＶ・オゾン処理、などの工程を入れる。これらの処理と、純水処理、アルカリ処理、界面活性剤（ＲＢＳなど）処理、などを適宜組み合わせる。これにより、基板に付着していたバクテリア等を除去することが可能となる。
本発明において、第３研磨工程（超精密研磨工程）に続いて第４研磨工程（最終超精密研磨工程）が実施される場合においては、前記研磨工程および前記洗浄工程は、第４研磨工程およびその後の洗浄工程、第３研磨工程およびその後の洗浄工程、のいずれか一方または双方であり、少なくとも第４研磨工程後およびその後の洗浄工程であることが好ましい。
本発明において、第３研磨工程（超精密研磨工程）が、最終磨工程である場合においては、前記研磨工程および前記洗浄工程は、第３研磨工程およびその後の洗浄工程である。
本発明において、純水としては、ＤＩＷ（Deionized water）を使用することが好ましい。ＤＩＷは、金属イオンや微生物などの不純物をほとんど含まない、純度１００％の理論的に水に限りなく近い高純度の純水である。
Hereinafter, the present invention will be described in detail.
The method for producing a glass substrate for mask blanks of the present invention is a method for producing a glass substrate for mask blanks, comprising a polishing step of performing double-side polishing on the surface of a glass substrate for mask blanks using a polishing liquid containing abrasive grains.
And having a cleaning step of treating the polished substrate with hydrofluoric acid, silicic hydrofluoric acid, or a cleaning liquid containing hydrofluoric acid and silicic hydrofluoric acid,
In the pure water tank for storing the substrate before performing the cleaning step, or having a means for irradiating ultraviolet light to the pure water circulation path of the pure water tank,
It is characterized by that.
According to the above configuration, the convex defect having the height of about several nm and the size of about 1 μm to 20 μm according to the present invention, which is considered to be caused by bacteria or the like, is not generated, or the generation rate can be reduced.
In the present invention, as a pure water tank for storing the substrate before the cleaning process, a pure water tank (pure water tank for storing the polished substrate) accompanying the polishing process, a water tank for transporting the substrate (for Water container), a loader water tank before hydrofluoric acid treatment in a cleaning device, and the like.
In the present invention, it is preferable to treat the substrate with hydrofluoric acid, silicic hydrofluoric acid, or a cleaning liquid containing hydrofluoric acid and silicic hydrofluoric acid without bacteria or the like adhering to the substrate.
For this purpose, it is preferable to store the substrate in a state free from bacteria (under the environment). For example, pure water in a pure water tank (pure water tank for storing the polished substrate) associated with the polishing process, a water tank for transporting the substrate (container for waste water), a loader water tank before hydrofluoric acid treatment in the cleaning device, etc. Examples include a method of supplying new (unused) pure water from the manufacturing apparatus and a method of taking measures for preventing bacteria and the like from being generated in these tanks.
It is also effective to make bacteria or the like not adhere to the substrate before hydrofluoric acid (etching) treatment. For example, before the hydrofluoric acid (etching) process, a process such as a scrub process, an ultrasonic / megasonic process, a UV / ozone process, or the like is added. These treatments are appropriately combined with pure water treatment, alkali treatment, surfactant (RBS etc.) treatment and the like. This makes it possible to remove bacteria and the like attached to the substrate.
In the present invention, when the fourth polishing step (final ultraprecision polishing step) is performed subsequent to the third polishing step (ultraprecision polishing step), the polishing step and the cleaning step are the fourth polishing step and Any one or both of the subsequent cleaning step, the third polishing step, and the subsequent cleaning step, and preferably at least after the fourth polishing step and the subsequent cleaning step.
In the present invention, when the third polishing step (ultra-precision polishing step) is a final polishing step, the polishing step and the cleaning step are a third polishing step and a subsequent cleaning step.
In the present invention, DIW (Deionized water) is preferably used as pure water. DIW is high-purity pure water that contains almost no impurities such as metal ions and microorganisms and has a purity of 100%, which is theoretically close to water.
本発明において、前記紫外線を照射する手段としては、紫外線（ＵＶ）照射装置が挙げられる。
本発明では、例えば、前記洗浄工程を行う前の基板を保管しておく純水槽内に紫外線照射装置を浸漬設置する。
本発明では、例えば、前記純水槽の純水循環経路（配管、ライン）に、紫外線（ＵＶ）照射装置を設ける。
本発明では、例えば、前記基板搬送用の水槽（ため水のコンテナ）に、紫外線（ＵＶ）照射装置を設ける。
本発明において、前記紫外線を照射する手段としては、紫外線殺菌灯、ＬＥＤ紫外線ライト、水銀ランプなどが挙げられる。
本発明において、前記紫外線を照射する手段としては、殺菌効果の高い水銀ランプが好ましい。また、酸化チタン等の紫外線によって光触媒反応を生じさせる構成と組み合わせるとより効果的である。例えば、紫外線が照射される領域の純水循環経路の内壁に酸化チタン等の光触媒材料をコーティングするなどが考えられる。
In the present invention, as the means for irradiating the ultraviolet rays, an ultraviolet (UV) irradiation device may be mentioned.
In the present invention, for example, an ultraviolet irradiation device is immersed in a pure water tank in which the substrate before the cleaning step is stored.
In the present invention, for example, an ultraviolet (UV) irradiation device is provided in the pure water circulation path (pipe, line) of the pure water tank.
In the present invention, for example, an ultraviolet (UV) irradiation device is provided in the water tank for transporting the substrate (container for water).
In the present invention, examples of the means for irradiating the ultraviolet rays include an ultraviolet germicidal lamp, an LED ultraviolet light, and a mercury lamp.
In the present invention, as the means for irradiating the ultraviolet rays, a mercury lamp having a high bactericidal effect is preferable. Further, it is more effective when combined with a structure that causes a photocatalytic reaction by ultraviolet rays such as titanium oxide. For example, a photocatalytic material such as titanium oxide may be coated on the inner wall of the pure water circulation path in the region irradiated with ultraviolet rays.
本発明において、前記純水槽の純水循環経路（配管、ライン）に、フィルタ手段を有することが好ましい。
死滅したバクテリアや分解されたバクテリア等をフィルタで捕捉するためである。なお、死滅したバクテリアは、基板表面で繁殖することは無いと考えられる。
フィルタの捕捉粒径は、０．０１〜０．０５μｍ程度が好ましい。
In this invention, it is preferable to have a filter means in the pure water circulation path (pipe, line) of the said pure water tank.
This is because the dead bacteria and the decomposed bacteria are captured by the filter. In addition, it is considered that dead bacteria do not propagate on the substrate surface.
The trapped particle size of the filter is preferably about 0.01 to 0.05 μm.
本発明において、前記洗浄工程を行う前の基板を保管しておく純水槽と、前記洗浄工程を行う洗浄槽との間に、純水処理と、超音波またはメガソニック処理とを組み合わせた処理を行う工程を設けることが好ましい。
前記洗浄工程を行う前の基板について、純水処理と、超音波またはメガソニック処理とを組み合わせた処理を行うことによって、基板に付着したバクテリア等を除去する効果があるからである。
純水処理と、超音波またはメガソニック処理とを組み合わせた処理としては、基板を純水槽に浸漬し純水槽（オーバーフロー）中で超音波またはメガソニック処理を行う態様や、基板に純水を吹きかける（シャワーなど）とともに超音波またはメガソニック処理を行う態様、などが挙げられる。
なお、メガソニック洗浄は、超音波洗浄より高周波（１ＭＨｚ程度）の超音波で洗浄する洗浄法である。メガソニック洗浄は、高周波な分、振動が細かくマイルドなので、超音波洗浄に比べ洗浄力は若干落ちるが、相対的に汚れの少ない第３および第４研磨工程（超精密研磨工程、最終（超精密）研磨工程）後のガラス基板の洗浄などに向いている。メガソニック洗浄は浸漬式、枚葉スピン式のどちらの装置でも適用出来る。メガソニック洗浄と超音波洗浄を組み合わせることもできる。
In the present invention, between the pure water tank for storing the substrate before performing the cleaning step and the cleaning tank for performing the cleaning step, a combination of pure water treatment and ultrasonic or megasonic treatment is performed. It is preferable to provide the process to perform.
This is because the substrate before the cleaning step is subjected to a treatment that combines pure water treatment and ultrasonic or megasonic treatment to remove bacteria and the like attached to the substrate.
As a treatment combining pure water treatment and ultrasonic or megasonic treatment, the substrate is immersed in a pure water bath and subjected to ultrasonic or megasonic treatment in the pure water bath (overflow), or pure water is sprayed on the substrate. A mode in which ultrasonic or megasonic treatment is performed together with (such as a shower).
Megasonic cleaning is a cleaning method in which cleaning is performed with ultrasonic waves having a higher frequency (about 1 MHz) than ultrasonic cleaning. Megasonic cleaning is fine and mild due to the high frequency, so the cleaning power is slightly lower than ultrasonic cleaning, but the third and fourth polishing processes (ultra-precision polishing process, final (ultra-precision) with relatively little dirt. ) Suitable for cleaning glass substrate after polishing step). Megasonic cleaning can be applied to both immersion type and single wafer spin type devices. Megasonic cleaning and ultrasonic cleaning can be combined.
本発明では、前記研磨後の基板を、フッ酸、ケイフッ酸、またはフッ酸及びケイフッ酸を含む洗浄液で処理する工程を有する。
本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥は、前記研磨後の基板を、フッ酸、ケイフッ酸、またはフッ酸及びケイフッ酸を含む洗浄液で処理する場合に特に問題となる。
In this invention, it has the process of processing the board | substrate after the said grinding | polishing with the washing | cleaning liquid containing a hydrofluoric acid, silicic acid, or hydrofluoric acid and silicic acid.
The convex defect having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention is a case where the polished substrate is treated with hydrofluoric acid, silicic acid, or a cleaning solution containing hydrofluoric acid and silicic acid. This is especially a problem.
本発明では、前記研磨後の基板を、フッ酸及び／又はケイフッ酸を含む洗浄液で洗浄する。通常、コロイダルシリカ砥粒を用いた研磨液によりガラス基板を精密研磨した後の洗浄としては、アルカリ洗浄や硫酸、塩酸等の洗浄が行われる。しかし、コロイダルシリカ砥粒には極微量のＦｅ、Ａｌ、Ｃａ、Ｍｇ、Ｔｉ、Ｃｕ、Ｎｉ、Ｃｒ等の不純物が含まれていることがあり、この不純物が精密研磨終了後にガラス基板表面に付着したことにより発生する高さ数ｎｍ程度、大きさが数十ｎｍ〜２μｍの凸状の突起を従来の洗浄方法をそのまま適用したのでは効果的に防止することができない（特許文献１参照）。フッ酸及び／又はケイフッ酸を含む洗浄液で洗浄することにより、これらの不純物を効果的に溶解除去でき、これらの不純物が原因の特許文献１記載の高さ数ｎｍ程度、大きさが数十ｎｍ〜２μｍの凸状の突起の発生を効果的に低減することができる。
前記研磨後の基板としては、例えば、前記最終研磨工程（第４研磨工程）実施後の基板や、前記超精密研磨工程（第３研磨工程）実施後の基板などが挙げられる。
本発明では、洗浄による表面粗さの悪化をなるべく防ぐために、フッ酸やケイフッ酸の濃度は、低い方が好ましい。すなわち、上述の不純物を溶解除去し、かつ、ガラス基板はあまりエッチングされない条件にすることにより、特許文献１記載の高さ数ｎｍ程度、大きさが数十ｎｍ〜２μｍの凸状の突起の高さ、並びに、本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥の高さ、を抑えることができる。よって、ガラス基板に対して比較的エッチング作用が弱いケイフッ酸、ケイフッ酸＋フッ酸、又は、低濃度のフッ酸を用いることによって、特許文献１記載の高さ数ｎｍ程度、大きさが数十ｎｍ〜２μｍの凸状の突起の高さ、並びに、本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥の高さ、を低減することができるのである。
フッ酸、ケイフッ酸の濃度としては、両者とも、０．００１〜０．５ｗｔ％が好ましい。
In the present invention, the substrate after polishing is cleaned with a cleaning solution containing hydrofluoric acid and / or silicic acid. Usually, as the cleaning after the glass substrate is precisely polished with a polishing liquid using colloidal silica abrasive grains, alkali cleaning, cleaning with sulfuric acid, hydrochloric acid or the like is performed. However, colloidal silica abrasive grains may contain trace amounts of impurities such as Fe, Al, Ca, Mg, Ti, Cu, Ni, and Cr, and these impurities adhere to the glass substrate surface after precision polishing is completed. Therefore, it is impossible to effectively prevent convex protrusions having a height of about several nanometers and a size of several tens of nanometers to 2 μm that are applied by the conventional cleaning method (see Patent Document 1). By washing with a cleaning solution containing hydrofluoric acid and / or silicic hydrofluoric acid, these impurities can be dissolved and removed effectively, and the height is about several nm and the size is several tens of nm described in Patent Document 1 due to these impurities. Generation | occurrence | production of convex protrusion of -2 micrometers can be reduced effectively.
Examples of the substrate after polishing include a substrate after the final polishing step (fourth polishing step) and a substrate after the ultraprecision polishing step (third polishing step).
In the present invention, the concentration of hydrofluoric acid or silicic hydrofluoric acid is preferably low in order to prevent deterioration of the surface roughness due to cleaning as much as possible. That is, by removing the above-mentioned impurities by dissolution and making the glass substrate not so etched, the height of the convex protrusion having a height of about several nanometers and a size of several tens of nanometers to 2 μm described in Patent Document 1. In addition, the height of the convex defect having a height of about several nm and a size of about 1 μm to 20 μm according to the present invention can be suppressed. Therefore, by using silicic acid, silicic acid + hydrofluoric acid, or low-concentration hydrofluoric acid, which has a relatively weak etching action on the glass substrate, a height of about several nanometers and a size of several tens are described in Patent Document 1. It is possible to reduce the height of the convex protrusion of nm to 2 μm and the height of the convex defect having a height of about several nm and a size of about 1 μm to 20 μm according to the present invention.
Both the concentration of hydrofluoric acid and silicic hydrofluoric acid are preferably 0.001 to 0.5 wt%.
本発明は、研磨砥粒はコロイダルシリカである場合に好適に適用できる。
本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥は、研磨砥粒としてコロイダルシリカを使用する研磨工程において問題となる。
コロイダルシリカは、例えば、第１および第２研磨工程（粗研磨、精密研磨）後の、超精密研磨工程（第３研磨工程）や、最終研磨工程（第４研磨工程）において研磨砥粒として使用される。
The present invention can be suitably applied when the abrasive grains are colloidal silica.
The convex defect having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention causes a problem in a polishing process using colloidal silica as polishing abrasive grains.
Colloidal silica is used as abrasive grains in the ultra-precision polishing step (third polishing step) and the final polishing step (fourth polishing step) after the first and second polishing steps (rough polishing, precision polishing), for example. Is done.
本発明において、研磨砥粒は、有機ケイ素化合物を加水分解することで生成したコロイダルシリカであることが好ましい。これにより、特許文献１記載の高さ数ｎｍ程度、大きさが数十ｎｍ〜２μｍの凸状の突起の発生が抑制される。
ここで、有機ケイ素化合物を加水分解することで生成したコロイダルシリカ砥粒とは、具体的には、例えば、金属不純物が除去された高純度アルコキシシランを原料にゾルゲル法で合成することによって、高純度なコロイダルシリカ砥粒としたもの等である。
上記の方法で合成、生成された高純度なコロイダルシリカ砥粒は、純度が９９．９９９９９％と極めて高く、しかも、Ｎａ、Ｋのアルカリ金属や、Ｆｅ、Ａｌ、Ｍｇ、Ｔｉ等の重金属といった不純物も極めて少ない。よって、後述するようなアルカリ金属によるゲル状物質や、重金属の不純物がガラス基板に付着し、付着した箇所がマスクとなって研磨速度の差やエッチングにより形成される特許文献１記載の高さ数ｎｍ程度、大きさが数十ｎｍ〜２μｍの凸状の突起の発生を抑えることができる。
In the present invention, the abrasive grains are preferably colloidal silica produced by hydrolyzing an organosilicon compound. Thereby, generation | occurrence | production of the convex processus | protrusion whose height is about several nm of patent document 1 size and several tens nm-2 micrometers is suppressed.
Here, the colloidal silica abrasive grains produced by hydrolyzing the organosilicon compound are specifically, for example, synthesized by a sol-gel method using a high-purity alkoxysilane from which metal impurities have been removed as a raw material. Such as a pure colloidal silica abrasive.
The high-purity colloidal silica abrasive grains synthesized and produced by the above method have an extremely high purity of 99.99999%, and impurities such as alkali metals such as Na and K and heavy metals such as Fe, Al, Mg and Ti. Is extremely small. Therefore, a gel-like substance made of alkali metal as will be described later, or heavy metal impurities adhere to the glass substrate, and the adhering portion serves as a mask to form a difference in polishing rate or the height described in Patent Document 1. Occurrence of convex protrusions having a size of about nm and a size of several tens of nm to 2 μm can be suppressed.
本発明では、前記研磨工程で使用する前記研磨液のｐＨが、９．６〜１１．０であることが好ましい。
前記研磨液のｐＨが、９．６〜１１．０である研磨工程は、例えば、第１および第２研磨工程（粗研磨、精密研磨）後の、超精密研磨工程（第３研磨工程）や、超精密研磨工程（第４研磨工程）が挙げられる。
In the present invention, the pH of the polishing liquid used in the polishing step is preferably 9.6 to 11.0.
The polishing step in which the pH of the polishing liquid is 9.6 to 11.0 is, for example, an ultra-precision polishing step (third polishing step) after the first and second polishing steps (rough polishing, precision polishing) And an ultra-precision polishing step (fourth polishing step).
本発明では、前記研磨工程における研磨の取り代が片面で１０μｍ以下であることが好ましい。
前記研磨工程における研磨の取り代が片面で１０μｍである（研磨の取り代が小さい）工程は、例えば、第１および第２研磨工程（粗研磨、精密研磨）後の、超精密研磨工程（第３研磨工程）や、超精密研磨工程（第４研磨工程）が挙げられる。
In this invention, it is preferable that the grinding allowance in the said grinding | polishing process is 10 micrometers or less on one side.
In the polishing step, the polishing allowance is 10 μm on one side (the polishing allowance is small), for example, an ultra-precision polishing step (first step) after the first and second polishing steps (rough polishing, precision polishing). 3 polishing step) and ultra-precision polishing step (fourth polishing step).
本発明では、前記研磨工程における研磨レートが２０ｎｍ／ｍｉｎ以下であることが好ましい。
前記研磨工程における研磨レートが２０ｎｍ／ｍｉｎ以下である（研磨の取り代が小さい）工程は、例えば、第１および第２研磨工程（粗研磨、精密研磨）後の、超精密研磨工程（第３研磨工程）や、超精密研磨工程（第４研磨工程）が挙げられる。
In the present invention, the polishing rate in the polishing step is preferably 20 nm / min or less.
The process in which the polishing rate in the polishing process is 20 nm / min or less (the polishing allowance is small) is, for example, an ultra-precision polishing process (third process) after the first and second polishing processes (rough polishing and precision polishing). Polishing process) and ultraprecision polishing process (fourth polishing process).
本発明において、前記研磨工程で使用する研磨布は軟質であることが好ましい。
前記研磨工程で使用する研磨布が軟質である工程は、例えば、第１および第２研磨工程（粗研磨、精密研磨）後の、超精密研磨工程（第３研磨工程）や、超精密研磨工程（第４研磨工程）が挙げられる。
In the present invention, the polishing cloth used in the polishing step is preferably soft.
The process in which the polishing cloth used in the polishing process is soft is, for example, an ultra-precision polishing process (third polishing process) or an ultra-precision polishing process after the first and second polishing processes (rough polishing and precision polishing). (4th grinding | polishing process) is mentioned.
本発明では、前記研磨液は、テトラメチルアンモニアを添加したものであることが好ましい。
前記研磨液がテトラメチルアンモニアを添加したものである研磨工程は、例えば、第１および第２研磨工程（粗研磨、精密研磨）、超精密研磨工程（第３研磨工程）後の、超精密研磨工程（第４研磨工程）が挙げられる。
本発明では、前記研磨液は、ＮａＯＨを添加したものであることが好ましい。
前記研磨液がＮａＯＨを添加したものである研磨工程は、例えば、第１および第２研磨工程（粗研磨、精密研磨）、超精密研磨工程（第３研磨工程）（最終研磨工程）が挙げられる。
In the present invention, the polishing liquid is preferably one to which tetramethylammonia is added.
The polishing step in which the polishing liquid is added with tetramethylammonia is, for example, ultraprecision polishing after the first and second polishing steps (rough polishing and precision polishing) and the ultraprecision polishing step (third polishing step). A process (4th grinding | polishing process) is mentioned.
In this invention, it is preferable that the said polishing liquid is what added NaOH.
Examples of the polishing step in which the polishing liquid is added with NaOH include first and second polishing steps (rough polishing and precision polishing), and ultra-precision polishing step (third polishing step) (final polishing step). .
精密研磨工程で使用されている研磨パッドは、基材である不織布の上に、発泡させた樹脂の表面をバフ研磨して開孔を露出させてナップ層を形成させたものが用いられる場合が多い。
本発明において、研磨パッド（研磨布）は、少なくとも、基材と、前記基材上に形成され、表面に開孔を有する発泡した樹脂からなるナップ層とからなる。
本発明において、発泡した樹脂としては、例えば、合成樹脂中にガスを細かく分散させ、内部に細かな泡を無数に含む、発泡状または多孔質形状に成形されたものを指し、固体である合成樹脂と気体の不均一分散系とも定義できる。
本発明において、発泡樹脂（ナップ層）としては、ウレタンが広く利用されている。
発泡樹脂（ナップ層）がポリウレタン樹脂である場合は、ポリウレタン樹脂を構成する原料樹脂として、ポリカーボネート系、ポリエステル系、ポリエーテル系などの樹脂や、これらの樹脂をブレンドした樹脂を用いることができる。
The polishing pad used in the precision polishing process may be one in which the surface of the foamed resin is buffed on the nonwoven fabric that is the base material to expose the apertures and a nap layer is formed. Many.
In the present invention, the polishing pad (polishing cloth) comprises at least a base material and a nap layer made of a foamed resin formed on the base material and having an opening on the surface.
In the present invention, the foamed resin is, for example, a resin that is formed into a foamed or porous shape in which a gas is finely dispersed in a synthetic resin and includes countless fine bubbles inside. It can also be defined as a non-uniform dispersion system of resin and gas.
In the present invention, urethane is widely used as the foamed resin (nap layer).
When the foamed resin (nap layer) is a polyurethane resin, a polycarbonate resin, a polyester resin, a polyether resin, or a resin obtained by blending these resins can be used as a raw material resin constituting the polyurethane resin.
本発明は、研磨対象物はガラス基板である場合に好適に適用できる。
本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥は、研磨対象物の材質がガラスである場合の研磨工程において問題となる。
本発明は、ガラス基板は両面同時に研磨する場合に好適に適用できる。
本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥は、ガラス基板を両面同時に研磨する研磨工程において問題となる。
The present invention can be suitably applied when the object to be polished is a glass substrate.
The convex defect having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention is a problem in the polishing process when the material of the object to be polished is glass.
The present invention can be suitably applied when a glass substrate is polished on both sides simultaneously.
The convex defect having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention is a problem in a polishing process in which both sides of a glass substrate are polished simultaneously.
本発明において、ガラス基板の材料としては、例えば、合成石英ガラス、石英ガラス、ホウケイ酸ガラス、アルミノシリケートガラス、アルミノボロシリケートガラス、ソーダライムガラス、無アルカリガラス、などが挙げられる。また、本発明は、例えばアモルファスガラスであれば、ＳｉＯ２−ＴｉＯ２系ガラス、結晶化ガラスであれば、β石英固溶体を析出した結晶化ガラス等の基板の研磨に適用できる。 In the present invention, examples of the material for the glass substrate include synthetic quartz glass, quartz glass, borosilicate glass, aluminosilicate glass, aluminoborosilicate glass, soda lime glass, and alkali-free glass. In addition, the present invention can be applied to polishing of a substrate such as a crystallized glass on which a β-quartz solid solution is precipitated if it is amorphous glass, for example, SiO 2 —TiO 2 glass, or crystallized glass.
本発明において、マスクブランクスとしては、フォトマスクブランクス、位相シフトマスクブランクス（ＡｒＦエキシマレーザー露光用位相シフトマスクブランクス、Ｆ２エキシマレーザー露光用位相シフトマスクブランクス）、Ｘ線やＥＵＶ用反射型マスクブランクスなどが挙げられ、用途としてはＬＳＩ（半導体集積回路）用マスクブランクス、ＬＣＤ（液晶表示板）用マスクブランクスなどが挙げられる。 In the present invention, the mask blank, a photomask blank, the phase shift mask blank (ArF excimer laser exposure phase shift mask blank, F 2 excimer laser exposure for phase shift mask blank), X-ray or EUV reflective mask blank such Applications include LSI (semiconductor integrated circuit) mask blanks, LCD (liquid crystal display) mask blanks, and the like.
上述の通り、本実施の形態にかかるマスクブランクス用ガラス基板の製造方法は、本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥により発生する位相差変化（位相欠陥）を抑えることができるため、特に、露光波長の短いリソグラフィーに使用されるＡｒＦエキシマレーザー露光用位相シフトマスクブランクス用ガラス基板、Ｆ２エキシマレーザー露光用位相シフトマスクブランクス用ガラス基板、ＥＵＶ反射型マスクブランクス用ガラス基板に特に効果がある。 As described above, the method for producing a mask blank glass substrate according to the present embodiment uses a phase difference change (phase) generated by a convex defect having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention. In particular, a glass substrate for a phase shift mask blank for ArF excimer laser exposure, a glass substrate for a phase shift mask blank for F 2 excimer laser exposure, and an EUV reflective type used in lithography with a short exposure wavelength. This is particularly effective for a glass substrate for mask blanks.
本発明のマスクブランクスの製造方法は、上記本発明のマスクブランクス用ガラス基板の製造方法によって製造したマスクブランクス用ガラス基板の主表面上に、露光光に対し光学的変化をもたらす薄膜を形成することを特徴とする
基板表面に本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥がないマスクブランクス用ガラス基板を使用してマスクブランクスを製造するので、マスクブランクス表面に位相欠陥等の表面欠陥のないマスクブランクスが得られる。
In the mask blank manufacturing method of the present invention, a thin film that causes an optical change with respect to exposure light is formed on the main surface of the mask blank glass substrate manufactured by the mask blank glass substrate manufacturing method of the present invention. Since mask blanks are manufactured using a glass substrate for mask blanks having no convex defects having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention on the substrate surface, the mask blanks surface Thus, mask blanks having no surface defects such as phase defects can be obtained.
ここで、露光光に対し光学的変化をもたらす薄膜とは、位相シフト膜（多層の場合を含む）又は遮光膜（多層の場合を含む）、あるいは位相シフト膜と遮光膜とを積層した膜や、位相シフト機能と遮光機能を有するハーフトーン膜（多層の場合を含む）、位相シフト機能を有さず、所定の透過率で露光光を透過させる半透過膜、反射膜、吸収体膜などを指す。従って、本発明でいうマスクブランクは広義の意味で用い、遮光膜のみが形成されたフォトマスクブランクのほか、位相シフト膜やハーフトーン膜などが形成された位相シフトマスクブランク、半透過膜などが形成されたエンハンサー用マスクブランク、更には反射膜と吸収体膜などが形成された反射型マスクブランクスが含まれる。 Here, the thin film that causes an optical change with respect to the exposure light is a phase shift film (including a multilayer case) or a light shielding film (including a multilayer case), or a film in which a phase shift film and a light shielding film are laminated. A halftone film (including multi-layer) having a phase shift function and a light shielding function, a semi-transmissive film that does not have a phase shift function and transmits exposure light at a predetermined transmittance, a reflective film, an absorber film, etc. Point to. Accordingly, the mask blank in the present invention is used in a broad sense, and includes a photomask blank in which only a light-shielding film is formed, a phase shift mask blank in which a phase shift film or a halftone film is formed, a semi-transmissive film, and the like. Enhancer mask blanks formed as well as reflective mask blanks formed with a reflective film and an absorber film are included.
本発明の転写マスクの製造方法は、上記本発明のマスクブランクスの製造方法で製造したマスクブランクスにおける前記薄膜をパターニングして、前記ガラス基板上に薄膜パターンを形成することを特徴とする。
上記本発明のマスクブランクスの製造方法によって得られたマスクブランクス表面に位相欠陥等の表面欠陥のないマスクブランクスを使用して転写マスクを製造するので、パターン欠陥のない転写マスクが得られる。
The transfer mask manufacturing method of the present invention is characterized by patterning the thin film in the mask blank manufactured by the mask blank manufacturing method of the present invention to form a thin film pattern on the glass substrate.
Since a transfer mask is manufactured by using a mask blank having no surface defects such as phase defects on the surface of the mask blank obtained by the mask blank manufacturing method of the present invention, a transfer mask having no pattern defect is obtained.
本発明の半導体装置の製造方法は、上記本発明の転写マスクの製造方法で製造した転写マスクを用いて、半導体基板上にリソグラフィー技術により微細パターンを形成することを特徴とする。
上記本発明の転写マスクの製造方法によって得られた転写マスク表面にパターン欠陥のない転写マスクを使用してリソグラフィー技術により半導体装置を製造するので、パターン欠陥のない半導体装置が得られる。
The semiconductor device manufacturing method of the present invention is characterized in that a fine pattern is formed on a semiconductor substrate by lithography using the transfer mask manufactured by the transfer mask manufacturing method of the present invention.
Since a semiconductor device is manufactured by lithography using a transfer mask having no pattern defect on the transfer mask surface obtained by the transfer mask manufacturing method of the present invention, a semiconductor device having no pattern defect is obtained.
本発明により得られるガラス基板は、ガラス基板の主表面内に主成分がＳｉとＯとを含み、本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥が存在しないマスクブランクス用ガラス基板である。位相欠陥の要因となる高さ数ｎｍ程度の凸状欠陥が、ガラス基板の主表面内に存在しないので、ガラス基板上に薄膜を形成してマスクブランクスにしたときに、位相欠陥等の表面欠陥のないマスクブランクスを提供することができる。このようなマスクブランクス用ガラス基板は、上記本発明のマスクブランクス用ガラス基板の製造方法によって製造することができる。 The glass substrate obtained by the present invention contains Si and O as main components in the main surface of the glass substrate, and there are convex defects having a height of about several nm and a size of about 1 μm to 20 μm according to the present invention. It is a glass substrate for mask blanks that does not. Since convex defects with a height of several nanometers that cause phase defects do not exist in the main surface of the glass substrate, surface defects such as phase defects are formed when a thin film is formed on the glass substrate to form mask blanks. Mask blanks without any problem can be provided. Such a glass substrate for mask blanks can be manufactured with the manufacturing method of the glass substrate for mask blanks of the said invention.
本発明により得られるマスクブランクスは、本発明により得られるマスクブランクス用ガラス基板の主表面上に、露光光に対し光学的変化をもたらす薄膜を形成することを特徴とするマスクブランクスである。基板表面に本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥がないマスクブランクス用ガラス基板を使用してマスクブランクスを製造するので、マスクブランクス表面に位相欠陥等の表面欠陥のないマスクブランクスが得られる。 The mask blank obtained by the present invention is a mask blank characterized by forming a thin film that causes an optical change with respect to exposure light on the main surface of the glass substrate for mask blank obtained by the present invention. Since mask blanks are manufactured using a glass substrate for mask blanks having no convex defects having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention on the substrate surface, phase defects and the like are formed on the surface of the mask blanks. Mask blanks free from surface defects are obtained.
本発明により得られる転写マスクは、本発明により得られるマスクブランクスにおける前記薄膜をパターニングして、前記ガラス基板上に薄膜パターンが形成されている転写マスクである。マスクブランクスの位相欠陥等の表面欠陥によるパターン欠陥がない転写マスクが得られる。 The transfer mask obtained by the present invention is a transfer mask in which a thin film pattern is formed on the glass substrate by patterning the thin film in the mask blank obtained by the present invention. A transfer mask free from pattern defects due to surface defects such as phase defects of mask blanks can be obtained.
［実施例］
以下、実施例に基づいて本発明をより具体的に説明する。以下の例では、マスクブランクス用ガラス基板として、位相シフトマスクブランクス用ガラス基板（以下、単にガラス基板と称する）を例に説明する。尚、本実施例における研磨の工程は、両面研磨装置を用いて行なう。図３は両面研磨装置の概略構成例を示す図である。図３に示した例は、遊星歯車方式の両面研磨装置である。この遊星歯車方式の両面研磨装置１は、太陽歯車２と、その外方に同心円状に配置される内歯歯車３と、太陽歯車２及び内歯歯車３に噛み合い、太陽歯車２や内歯歯車３の回転に応じて公転及び自転するキャリア４と、このキャリア４に保持された被研磨加工物５（ガラス基板）を研磨パッド６が貼着された挟持可能な上定盤７及び下定盤８と、上定盤７と下定盤８との間に研磨液を供給する研磨液供給部９とを備えている。
[Example]
Hereinafter, based on an Example, this invention is demonstrated more concretely. In the following example, a glass substrate for phase shift mask blanks (hereinafter simply referred to as a glass substrate) will be described as an example of a glass substrate for mask blanks. The polishing process in this embodiment is performed using a double-side polishing apparatus. FIG. 3 is a diagram showing a schematic configuration example of a double-side polishing apparatus. The example shown in FIG. 3 is a planetary gear type double-side polishing apparatus. This planetary gear type double-side polishing apparatus 1 meshes with a sun gear 2, an internal gear 3 arranged concentrically on the outer side, the sun gear 2 and the internal gear 3, and the sun gear 2 and the internal gear. 3, an upper surface plate 7 and a lower surface plate 8 on which a polishing pad 6 is attached to a workpiece 5 (glass substrate) held by the carrier 4 that revolves and rotates in response to the rotation of 3. And a polishing liquid supply unit 9 for supplying a polishing liquid between the upper surface plate 7 and the lower surface plate 8.
研磨加工時には、キャリア４に保持された被研磨加工物５を上定盤７及び下定盤８に挟持するとともに、上下定盤の研磨パッド６と被研磨加工物５との間に研磨液を供給しながら太陽歯車２や内歯歯車３の回転に応じて、キャリア４が公転及び自転しながら、被研磨加工物５の上下両面を同時に研磨加工する。両面研磨装置１には、太陽歯車３、内歯歯車４、上定盤７、下定盤８、これらの回転数と回転時間、及び荷重シーケンス（研磨時間と荷重）を設定し、制御する動作制御部１０（図示せず）が接続されており、予め設定した太陽歯車３、内歯歯車４、上定盤７、下定盤８の回転数と回転時間、及び加工荷重にしたがって、被研磨加工物５を研磨加工するようになっている。 At the time of polishing, the workpiece 5 held by the carrier 4 is sandwiched between the upper surface plate 7 and the lower surface plate 8, and the polishing liquid is supplied between the polishing pad 6 of the upper and lower surface plates and the workpiece 5 to be polished. While the carrier 4 rotates and rotates according to the rotation of the sun gear 2 and the internal gear 3, the upper and lower surfaces of the workpiece 5 are simultaneously polished. The double-side polishing apparatus 1 sets and controls the sun gear 3, the internal gear 4, the upper surface plate 7, the lower surface plate 8, their rotation speed and rotation time, and load sequence (polishing time and load). Workpieces to be polished are connected in accordance with the rotation speed and rotation time of the sun gear 3, the internal gear 4, the upper surface plate 7, the lower surface plate 8, and the processing load set in advance. 5 is polished.
（実施例１〜２、比較例１〜４）
（マスクブランクス用ガラス基板の製造）
（１）粗研磨工程
合成石英ガラス基板（１５２．４ｍｍ×１５２．４ｍｍ）の端面を面取加工、及び両面ラッピング装置によって研削加工を終えたガラス基板を、両面研磨装置に１０枚セットし、以下の研磨条件で粗研磨工程を行った。１０枚セットを１０回行い合計１００枚のガラス基板の粗研磨工程を行った。尚、加工荷重、研磨時間は適宜調整して行った。
研磨液：酸化セリウム（平均粒径２〜３μｍ）＋水
研磨パッド：硬質ポリシャ（ウレタンパッド）
粗研磨工程後、ガラス基板に付着した研磨砥粒を除去するため、ガラス基板を洗浄槽に浸漬（超音波印加）し、洗浄を行った。
(Examples 1-2, Comparative Examples 1-4)
(Manufacture of glass substrates for mask blanks)
(1) Rough Polishing Step 10 glass substrates that have been finished with chamfering and grinding by a double-sided lapping device on the end surface of a synthetic quartz glass substrate (152.4 mm × 152.4 mm) are set in a double-side polishing device. The rough polishing process was performed under the following polishing conditions. A set of 10 sheets was performed 10 times to perform a rough polishing step on a total of 100 glass substrates. The processing load and polishing time were adjusted as appropriate.
Polishing liquid: Cerium oxide (average particle size 2 to 3 μm) + water Polishing pad: Hard polisher (urethane pad)
After the rough polishing step, the glass substrate was immersed in a cleaning tank (ultrasonic application) in order to remove the abrasive grains adhering to the glass substrate and cleaned.
（２）精密研磨工程
両面研磨装置に１０枚セットし、以下の研磨条件で精密研磨工程を行った。１０枚セットを１０回行い合計１００枚のガラス基板の精密研磨工程を行った。尚、加工荷重、研磨時間は適宜調整して行った。
研磨液：酸化セリウム（平均粒径１μｍ）＋水
研磨パッド：軟質ポリシャ（スウェードタイプ）
精密研磨工程後、ガラス基板に付着した研磨砥粒を除去するため、ガラス基板を洗浄槽に浸漬（超音波印加）し、洗浄を行った。
(2) Precision polishing process Ten sheets were set in a double-side polishing apparatus, and a precision polishing process was performed under the following polishing conditions. A 10-sheet set was performed 10 times to perform a precision polishing step for a total of 100 glass substrates. The processing load and polishing time were adjusted as appropriate.
Polishing liquid: Cerium oxide (average particle size 1μm) + water Polishing pad: Soft polisher (suede type)
After the precision polishing step, in order to remove the abrasive grains adhering to the glass substrate, the glass substrate was immersed in a cleaning tank (ultrasonic application) and cleaned.
（３）超精密研磨工程１（第３ポリシング）
両面研磨装置に１０枚セットし、以下の研磨条件で超精密研磨工程を行った。
１０枚セットを１０回行い合計１００枚のガラス基板の超精密研磨工程を行った。尚、加工荷重、研磨時間は位相シフトマスクブランクスに使用するガラス基板として必要な表面粗さ（所望の表面粗さ：二乗平均平方根粗さＲｑで０．２ｎｍ以下）となるように適宜調整して行った。
研磨液：アルカリ性（ｐＨ１０．２）；コロイダルシリカ（平均粒径３０〜２００ｎｍ）＋水
研磨パッド：超軟質ポリシャ（スウェードタイプ）；バフ処理発泡樹脂／不織布（基材）の構成のもの使用
超精密研磨工程１を実施後、ガラス基板に付着した研磨砥粒を除去するため、ガラス基板を、ケイフッ酸（０．２ｗｔ％）を含む洗浄液が入った洗浄槽に浸漬（超音波印加）し、洗浄を行った。
(3) Ultra-precision polishing process 1 (third polishing)
Ten sheets were set in a double-side polishing apparatus, and an ultraprecision polishing process was performed under the following polishing conditions.
A 10-sheet set was performed 10 times to perform a super-precision polishing step on a total of 100 glass substrates. The processing load and polishing time are appropriately adjusted so that the surface roughness necessary for the glass substrate used for the phase shift mask blanks (desired surface roughness: root mean square roughness Rq is 0.2 nm or less). went.
Polishing liquid: Alkaline (pH 10.2); Colloidal silica (average particle size 30 to 200 nm) + water Polishing pad: Super soft polisher (suede type); Buffed foam resin / nonwoven fabric (base material) After carrying out the polishing step 1, in order to remove the abrasive grains adhering to the glass substrate, the glass substrate is immersed in a cleaning tank containing a cleaning solution containing silicic acid (0.2 wt%) (ultrasonic application) and cleaned. Went.
（４）最終研磨工程（超精密研磨工程２、第４ポリシング）
両面研磨装置に１０枚セットし、以下の研磨条件で超精密研磨工程を行った。
１０枚セットを１０回行い合計１００枚のガラス基板の超精密研磨工程を行った。尚、加工荷重、研磨時間は位相シフトマスクブランクスに使用するガラス基板として必要な表面粗さ（所望の表面粗さ：二乗平均平方根粗さＲｑで0.2ｎｍ以下）となるように適宜調整して行った。
研磨液：アルカリ性（ｐＨ １０ ）；コロイダルシリカ（平均粒径８０ｎｍ）＋水（水酸化テトラメチルアンモニウム（TMAH：Tetramethyl ammonium hydroxide）添加）
研磨パッド：超軟質ポリシャ（スウェードタイプ）；バフ処理発泡樹脂／フェルト（基材）の構成で、発泡樹脂は１００％樹脂モジュラスで、２０〜３０ＭＰａ（軟質）のものを使用
加工荷重： ３０ｇ／ｃｍ２
研磨時間： ２０ 分
基板回転数： ６ｒｐｍ
研磨定盤回転数：１２ｒｐｍ
最終研磨工程（超精密研磨工程２）終了後、研磨が終了したガラス基板５〜１０枚をカセットに入れ、バンドシャワーをかけ、研磨工程に付随する純水槽に保管した。その後、カセットに入れたガラス基板を、基板搬送用の水槽（ため水のコンテナ）で搬送し、洗浄装置におけるローダー水槽にセットした。洗浄装置においては、ローダー水槽から、純水オバーフロー＋メガソニック１分、フッ酸＋ケイフッ酸＋メガソニック１分、フッ酸＋ケイフッ酸＋メガソニック１分、純水スクラブ洗浄、純水オバーフロー＋メガソニック、スピンすすぎ、スピン乾燥で処理した。
図１に示すように、洗浄装置におけるローダー水槽１０には、純水製造装置（図示せず）から配管１５を介して新純水が供給される。ローダー水槽１０においては、オーバーフローさせた純水は、純水循環経路１１に設けたポンプ１２によって、純水循環経路１１を通って、ローダー水槽１０に供給される。純水循環経路１１には、紫外線照射手段１３として、水銀ランプが設けられている。水銀ランプを設ける箇所の配管は透明とし、純水循環経路中を流れる純水に紫外線を照射する。純水循環経路１１には、フィルタ１４として、捕捉粒径０．２μｍのフィルタが設けられている。
洗浄装置においては、ローダー水槽１０、純水オバーフロー槽２０、フッ酸＋ケイフッ酸処理槽３０、フッ酸＋ケイフッ酸処理槽３１、に順次浸漬され、処理される。純水オバーフロー槽２０、フッ酸＋ケイフッ酸処理槽３０、フッ酸＋ケイフッ酸処理槽３１は、それぞれ、メガソニック処理が付加されている。
純水としては、ＤＩＷ（Deionized water）を使用した。
(4) Final polishing process (ultra-precision polishing process 2, fourth polishing)
Ten sheets were set in a double-side polishing apparatus, and an ultraprecision polishing process was performed under the following polishing conditions.
A 10-sheet set was performed 10 times to perform a super-precision polishing step on a total of 100 glass substrates. The processing load and polishing time are appropriately adjusted so that the surface roughness required for the glass substrate used in the phase shift mask blanks (desired surface roughness: root mean square roughness Rq is 0.2 nm or less). It was.
Polishing liquid: Alkaline (pH 10); colloidal silica (average particle size 80 nm) + water (addition of tetramethylammonium hydroxide (TMAH))
Polishing pad: Super soft polisher (suede type); buffed foam resin / felt (base material), foam resin is 100% resin modulus, 20-30 MPa (soft) processing load: 30 g / cm 2
Polishing time: 20 minutes Substrate rotation speed: 6 rpm
Polishing platen rotation speed: 12rpm
After completion of the final polishing step (ultra-precision polishing step 2), 5 to 10 glass substrates after polishing were put in a cassette, subjected to a band shower, and stored in a pure water tank accompanying the polishing step. Then, the glass substrate put into the cassette was conveyed with the water tank (container of irrigation water) for board | substrate conveyance, and was set to the loader water tank in a washing | cleaning apparatus. In the cleaning equipment, pure water overflow + megasonic 1 minute, hydrofluoric acid + silicic acid + megasonic 1 minute, hydrofluoric acid + silicic acid + megasonic 1 minute, pure water scrub cleaning, pure water overflow + mega Processed by sonic, spin rinse and spin dry.
As shown in FIG. 1, new pure water is supplied to a loader water tank 10 in a cleaning apparatus from a pure water manufacturing apparatus (not shown) through a pipe 15. In the loader water tank 10, the overflowed pure water is supplied to the loader water tank 10 through the pure water circulation path 11 by a pump 12 provided in the pure water circulation path 11. The pure water circulation path 11 is provided with a mercury lamp as the ultraviolet irradiation means 13. The piping where the mercury lamp is installed is transparent, and the pure water flowing in the pure water circulation path is irradiated with ultraviolet rays. In the pure water circulation path 11, a filter having a trapped particle diameter of 0.2 μm is provided as the filter 14.
In the cleaning device, the loader water tank 10, the pure water overflow tank 20, the hydrofluoric acid + silicic acid treatment tank 30, and the hydrofluoric acid + silicic acid treatment tank 31 are sequentially immersed and processed. The pure water overflow tank 20, the hydrofluoric acid + silicic acid treatment tank 30, and the hydrofluoric acid + silicic acid treatment tank 31 are respectively subjected to megasonic treatment.
DIW (Deionized water) was used as pure water.
比較例１では、基板搬送用の水槽（ため水のコンテナ）は、生菌数２５００（ＣＦＵ／ｍｌ）、全有機炭素量１．３（ｍｇ／ｌ）、０．３μｍ以下のパーティクル数５４６４９６（ｃｏｕｎｔ／ｍｌ）であった。
比較例１では、上記基板搬送用の水槽（ため水のコンテナ）に浸漬されている基板を取り出し、直接（純水オバーフロー槽２０は介在させないで）、前記フッ酸＋ケイフッ酸処理槽３０、３１で洗浄を行った。
その結果、本発明に係る上記高さ数ｎｍ程度、大きさが５μｍ〜２０μｍ程度の凸状欠陥は、極めて多数（具体的には２００個／ｃｍ２）検出された。
In Comparative Example 1, the water tank for transporting the substrate (container for irrigation water) has a viable cell count of 2500 (CFU / ml), a total organic carbon content of 1.3 (mg / l), and a number of particles of 546,496 ( count / ml).
In Comparative Example 1, the substrate immersed in the water tank for transporting the substrate (water container) is taken out and directly (without the pure water overflow tank 20), the hydrofluoric acid + silicic acid hydrofluoric acid treatment tanks 30, 31 are used. And washed.
As a result, a very large number (specifically, 200 / cm 2 ) of convex defects having a height of about several nm and a size of about 5 μm to 20 μm according to the present invention were detected.
比較例２では、基板搬送用の水槽（ため水のコンテナ）は、生菌数２５００（ＣＦＵ／ｍｌ）、全有機炭素量１．３（ｍｇ／ｌ）、０．３μｍ以下のパーティクル数５４６４９６（ｃｏｕｎｔ／ｍｌ）であった。
比較例２では、上記基板搬送用の水槽（ため水のコンテナ）に浸漬されている基板を取り出し、純水オバーフロー槽２０（メガソニック有り）、フッ酸＋ケイフッ酸処理槽３０（メガソニック有り）、フッ酸＋ケイフッ酸処理槽３１（メガソニック有り）で洗浄を行った。
その結果、本発明に係る上記高さ数ｎｍ程度、大きさが５μｍ〜２０μｍ程度の凸状欠陥は、１５０個／ｃｍ２であった。
In Comparative Example 2, the water tank for transporting the substrate (container for irrigation water) has a viable count of 2500 (CFU / ml), a total organic carbon content of 1.3 (mg / l), and a number of particles of 546,496 ( count / ml).
In Comparative Example 2, the substrate immersed in the water tank for transporting the substrate (container for water) is taken out, and the pure water overflow tank 20 (with megasonic), hydrofluoric acid + silicic acid hydrofluoric acid treatment tank 30 (with megasonic) Cleaning was performed in a hydrofluoric acid + silicic acid hydrofluoric acid treatment tank 31 (with Megasonic).
As a result, the number of convex defects having a height of about several nm and a size of about 5 μm to 20 μm according to the present invention was 150 / cm 2 .
比較例３では、ローダー水槽１０は、生菌数１５００（ＣＦＵ／ｍｌ）、全有機炭素量１．１（ｍｇ／ｌ）、０．３μｍ以下のパーティクル数７４０１８（ｃｏｕｎｔ／ｍｌ）であった。
比較例３では、上記ローダー水槽１０に浸漬されている基板を取り出し、直接（純水オバーフロー槽２０は介在させないで）、前記フッ酸＋ケイフッ酸処理槽３０、３１で洗浄を行った。
その結果、本発明に係る上記高さ数ｎｍ程度、大きさが５μｍ〜２０μｍ程度の凸状欠陥は、極めて多数（具体的には１５０個／ｃｍ２）検出された。
In Comparative Example 3, the loader water tank 10 had a viable cell count of 1500 (CFU / ml), a total organic carbon content of 1.1 (mg / l), and a particle count of 7418 (count / ml) of 0.3 μm or less.
In Comparative Example 3, the substrate immersed in the loader water tank 10 was taken out and washed directly (without the pure water overflow tank 20) in the hydrofluoric acid + silicic acid hydrofluoric acid treatment tanks 30 and 31.
As a result, an extremely large number (specifically, 150 / cm 2 ) of convex defects having a height of about several nm and a size of about 5 μm to 20 μm according to the present invention were detected.
比較例４では、ローダー水槽１０は、生菌数１５００（ＣＦＵ／ｍｌ）、全有機炭素量１．１（ｍｇ／ｌ）、０．３μｍ以下のパーティクル数７４０１８（ｃｏｕｎｔ／ｍｌ）であった。
比較例４では、上記ローダー水槽１０に浸漬されている基板を取り出し、純水オバーフロー槽２０（メガソニック有り）、フッ酸＋ケイフッ酸処理槽３０（メガソニック有り）、フッ酸＋ケイフッ酸処理槽３１（メガソニック有り）で洗浄を行った。
その結果、本発明に係る上記高さ数ｎｍ程度、大きさが５μｍ〜２０μｍ程度の凸状欠陥は、１００個／ｃｍ２であった。
In Comparative Example 4, the loader water tank 10 had a viable cell count of 1500 (CFU / ml), a total organic carbon content of 1.1 (mg / l), and a particle count of 7418 (count / ml) of 0.3 μm or less.
In Comparative Example 4, the substrate immersed in the loader water tank 10 is taken out and the pure water overflow tank 20 (with megasonic), hydrofluoric acid + silicic acid treatment tank 30 (with megasonic), hydrofluoric acid + silicic acid treatment tank Washing was performed at 31 (with megasonic).
As a result, the number of convex defects having a height of about several nm and a size of about 5 μm to 20 μm according to the present invention was 100 / cm 2 .
実施例１では、基板搬送用の水槽（ため水のコンテナ）は、純水製造装置から供給される新しい純水を使用し、生菌数は検出されず（ＣＦＵ／ｍｌ）、全有機炭素量 検出下限値以下、０．３μｍ以下のパーティクル数 ５００（ｃｏｕｎｔ／ｍｌ）であった。また、ローダー水槽１０は、生菌数は検出されず（ＣＦＵ／ｍｌ）、全有機炭素量０．１（ｍｇ／ｌ）、０．３μｍ以下のパーティクル数１２３５９〜１３６０３（ｃｏｕｎｔ／ｍｌ）であった。
実施例１では、上記ローダー水槽１０に浸漬されている基板を取り出し、純水オバーフロー槽２０（メガソニック有り）、フッ酸＋ケイフッ酸処理槽３０（メガソニック有り）、フッ酸＋ケイフッ酸処理槽３１（メガソニック有り）で洗浄を行った。
その結果、本発明に係る上記高さ数ｎｍ程度、大きさが５μｍ〜２０μｍ程度の凸状欠陥は、発生なし（ゼロ）であった。
In Example 1, the water tank for transporting the substrate (container for irrigation water) uses new pure water supplied from the pure water production apparatus, the viable cell count is not detected (CFU / ml), and the total amount of organic carbon The number of particles below the detection lower limit and below 0.3 μm was 500 (count / ml). The loader water tank 10 had no viable count (CFU / ml), a total organic carbon content of 0.1 (mg / l), and a particle count of 12359 to 13603 (count / ml) of 0.3 μm or less. It was.
In Example 1, the substrate immersed in the loader water tank 10 is taken out, and a pure water overflow tank 20 (with megasonic), hydrofluoric acid + silicic acid treatment tank 30 (with megasonic), hydrofluoric acid + silicic acid treatment tank. Washing was performed at 31 (with megasonic).
As a result, the convex defect having a height of about several nm and a size of about 5 μm to 20 μm according to the present invention was not generated (zero).
実施例２では、基板搬送用の水槽（ため水のコンテナ）は、生菌数は検出されず（ＣＦＵ／ｍｌ）、全有機炭素量 検出下限値以下、０．３μｍ以下のパーティクル数 ５００（ｃｏｕｎｔ／ｍｌ）であった。また、ローダー水槽１０は、生菌数は検出されず（ＣＦＵ／ｍｌ）、全有機炭素量０．１（ｍｇ／ｌ）、０．３μｍ以下のパーティクル数１２３５９〜１３６０３（ｃｏｕｎｔ／ｍｌ）であった。
実施例１では、上記ローダー水槽１０に浸漬されている基板を取り出し、直接（純水オバーフロー槽２０は介在させないで）、前記フッ酸＋ケイフッ酸処理槽３０、３１で洗浄を行った。
その結果、本発明に係る上記高さ数ｎｍ程度、大きさが５μｍ〜２０μｍ程度の凸状欠陥は、ゼロ（発生なし）であった。
In Example 2, the number of viable bacteria (CFU / ml) is not detected in the water tank (container) for transporting the substrate (CFU / ml), the total organic carbon content is less than the detection lower limit value, and the number of particles of 0.3 μm or less 500 (count / Ml). The loader water tank 10 had no viable count (CFU / ml), a total organic carbon content of 0.1 (mg / l), and a particle count of 12359 to 13603 (count / ml) of 0.3 μm or less. It was.
In Example 1, the board | substrate immersed in the said loader water tank 10 was pick_out | removed, and it wash | cleaned with the said hydrofluoric acid + silicic acid processing tanks 30 and 31 directly (without interposing the pure water overflow tank 20).
As a result, the convex defect having a height of about several nm and a size of about 5 μm to 20 μm according to the present invention was zero (no occurrence).
なお、上述の実施例及び比較例で確認された本発明に係る上記高さ数ｎｍ程度、大きさが５μｍ〜２０μｍ程度の凸状欠陥を分析したところ、ＴＥＭ−ＥＤＸ分析（透過型電子顕微鏡に付属するエネルギー分散型X線分光装置）では、界面及び特異元素は確認できないことから石英（主成分がＳｉ、Ｏを含むもの）の段差であることを解明した。ＡＭＦ（原子間力顕微鏡）で分析したところ、高さは４μｍ程度であった。 When the convex defects having a height of about several nanometers and a size of about 5 μm to 20 μm according to the present invention confirmed in the above-described examples and comparative examples were analyzed, TEM-EDX analysis (for transmission electron microscope) In the attached energy dispersive X-ray spectrometer, the interface and specific elements could not be confirmed, so it was elucidated that it was a step of quartz (the main component contains Si and O). When analyzed by AMF (atomic force microscope), the height was about 4 μm.
（実施例３）
上述の実施例１において、超精密研磨工程１、２で使用する研磨液を以下のようにした以外は実施例１と同様にしてマスクブランクス用ガラス基板を作製した。
研磨液：高純度コロイダルシリカ（平均粒径３０〜１００ｎｍ）＋水
高純度コロイダルシリカ：有機ケイ素を加水分解することで生成したコロイダルシリカであって、金属不純物が除去された高純度アルコキシシランを原料にゾルゲル法により合成したもの。純度が９９．９９９９９％。コロイダルシリカ砥粒に含まれるアルカリ金属（Ｎａ，Ｋ）の含有量が０．１ｐｐｍ以下。
超精密研磨工程１実施後、及び、超精密研磨工程２実施後に、それぞれ、得られたガラス基板の主表面をレーザー干渉コンフォーカル光学系による欠陥検査装置を用いて特許文献１記載の高さ数ｎｍ程度（約２〜７ｎｍ）、大きさが数十ｎｍ〜２μｍの凸状の突起を調べたところ、いずれの場合においても、このような表面欠陥は全く確認できず、高さ数ｎｍ程度の凸状の突起の発生率は０％（１００枚中０枚）であった。
(Example 3)
In Example 1 described above, a glass substrate for mask blanks was produced in the same manner as Example 1 except that the polishing liquid used in the ultraprecision polishing steps 1 and 2 was as follows.
Polishing liquid: High-purity colloidal silica (average particle size 30 to 100 nm) + water High-purity colloidal silica: Colloidal silica produced by hydrolyzing organosilicon, which is made from high-purity alkoxysilane from which metal impurities have been removed And synthesized by the sol-gel method. The purity is 99.99999%. The content of alkali metal (Na, K) contained in the colloidal silica abrasive is 0.1 ppm or less.
After performing the ultra-precision polishing step 1 and after performing the ultra-precision polishing step 2, the main surfaces of the obtained glass substrates are each measured by using a defect inspection apparatus using a laser interference confocal optical system. When a convex protrusion having a size of about nm (about 2 to 7 nm) and a size of several tens of nm to 2 μm was examined, in any case, such a surface defect could not be confirmed at all, and the height was about several nm. The incidence of convex protrusions was 0% (0 out of 100 sheets).
（マスクブランクスの製造）
また、上述の実施例１〜３にかかるマスクブランクス用ガラス基板の製造方法によって製造した本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥（実施例１、２）、さらには特許文献１記載の高さ数ｎｍ程度の凸状欠陥（実施例３）、のないマスクブランクス用ガラス基板、並びに、上述の比較例１〜４の製造方法によって製造した本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥のあるガラス基板の一主表面上に、モリブデンシリサイド窒化膜からなるハーフトーン膜をスパッタリング法により形成した。
(Manufacture of mask blanks)
Moreover, the convex defect (Examples 1 and 2) manufactured by the method for manufacturing a mask blank glass substrate according to Examples 1 to 3 and having a height of about several nm and a size of about 1 μm to 20 μm according to the present invention. ), And a glass substrate for mask blanks having no convex defect of about several nanometers height described in Patent Document 1 (Example 3), and the present invention manufactured by the manufacturing method of Comparative Examples 1 to 4 described above. A halftone film made of a molybdenum silicide nitride film was formed by sputtering on one main surface of the glass substrate having a convex defect having a height of about several nm and a size of about 1 μm to 20 μm.
こうして作製したモリブデンシリサイド窒化膜からなるハーフトーン膜の欠陥検査を行ったところ、実施例１〜３にかかるマスクブランクス用ガラス基板の製造方法によって製造したマスクブランクス用ガラス基板を用いた位相シフトマスクブランクスには本発明に係る上記高さ数ｎｍ程度、大きさが５μｍ〜２０μｍ程度の凸状欠陥（実施例１、２）、さらには特許文献１記載の凸状の表面欠陥（実施例３）は認められなかった。これに対し、本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥が確認されたマスクブランクス用ガラス基板（比較例１〜４）を使って作製した位相シフトマスクブランクスにおいては、ハーフトーン膜表面に本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状の表面欠陥が確認された。 When the defect inspection of the half-tone film made of the molybdenum silicide nitride film thus manufactured was performed, the phase shift mask blank using the mask blank glass substrate manufactured by the method for manufacturing a mask blank glass substrate according to Examples 1 to 3 was used. The convex defect (Examples 1 and 2) having a height of about several nanometers and a size of about 5 μm to 20 μm according to the present invention, and the convex surface defect (Example 3) described in Patent Document 1 are I was not able to admit. On the other hand, the phase shift mask produced using the glass substrate for mask blanks (Comparative Examples 1 to 4) in which convex defects having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention were confirmed. In the blanks, convex surface defects having a height of about several nm and a size of about 1 μm to 20 μm according to the present invention were confirmed on the surface of the halftone film.
さらに、欠陥検査後の実施例１〜３および比較例１〜４にかかるマスクブランクス用ガラス基板におけるハーフトーン膜の上に、酸窒化炭化クロム、窒化クロム、酸窒化炭化クロムの３層積層構造の遮光膜をスパッタリング法により形成し、位相シフトマスクブランクスを作製した。 Furthermore, on the halftone film in the glass substrate for mask blanks according to Examples 1 to 3 and Comparative Examples 1 to 4 after the defect inspection, a three-layer laminated structure of chromium oxynitride carbide, chromium nitride, and chromium oxynitride carbide A light shielding film was formed by a sputtering method, and phase shift mask blanks were produced.
（位相シフトマスクの製造）
上述の本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥（実施例１、２）、さらには特許文献１記載の凸状欠陥（実施例３）が認められなかった位相シフトマスクブランクス、及び本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥が確認された位相シフトマスクブランクス（比較例１〜４）上にレジスト膜を形成し、さらに、レジスト膜をパターニングしてレジストパターンとした。次に、このレジストパターンをマスクにして、遮光膜をドライエッチングによりパターニングした。次に、パターンが形成された遮光膜をマスクにして、ハーフトーン膜をドライエッチングによりパターニングした。さらに、遮光帯用のレジストパターンを形成し、そのレジストパターンをマスクにして、遮光膜をドライエッチングして遮光帯を形成した。以上の工程により、ガラス基板上にハーフトーン膜パターンと遮光帯が形成された位相シフトマスクを作製した。
(Manufacture of phase shift mask)
Convex defects (Examples 1 and 2) having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention described above, and a convex defect described in Patent Document 1 (Example 3) are recognized. The resist film was formed on the phase shift mask blanks (Comparative Examples 1 to 4) in which convex defects having a height of about several nanometers and a size of about 1 μm to 20 μm were confirmed. Then, the resist film was patterned to obtain a resist pattern. Next, the light shielding film was patterned by dry etching using this resist pattern as a mask. Next, the halftone film was patterned by dry etching using the light-shielding film on which the pattern was formed as a mask. Further, a resist pattern for a light shielding band was formed, and the light shielding film was dry etched using the resist pattern as a mask to form a light shielding band. Through the above steps, a phase shift mask having a halftone film pattern and a light shielding band formed on a glass substrate was produced.
こうして作製した位相シフトマスクについて、表面欠陥を確認したところ、本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状欠陥（実施例１、２）、さらには特許文献１記載の凸状の表面欠陥（実施例３）のないガラス基板を使って作製した位相シフトマスクには、位相欠陥は確認されなかったが、比較例１〜４のガラス基板を使って作製した位相シフトマスクに、ガラス基板表面とハーフトーン膜パターンの境界に本発明に係る上記高さ数ｎｍ程度、大きさが１μｍ〜２０μｍ程度の凸状の表面欠陥が確認され位相欠陥となった。 When the surface defect was confirmed about the phase shift mask produced in this way, the convex defect (Examples 1 and 2) having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention, and Patent Document 1 Although the phase defect was not confirmed in the phase shift mask produced using the glass substrate without the convex surface defect (Example 3) of description, the phase produced using the glass substrate of Comparative Examples 1-4. In the shift mask, convex surface defects having a height of about several nanometers and a size of about 1 μm to 20 μm according to the present invention were confirmed at the boundary between the glass substrate surface and the halftone film pattern, thereby forming phase defects.
（半導体装置の製造）
また、これら位相欠陥が確認された位相シフトマスク（比較例１〜４）を使って露光機により半導体基板上にリソグラフィー技術により微細パターンを形成したところ、位相シフトマスクの位相欠陥要因のパターン欠陥が確認されたが、位相欠陥が確認されなかった位相シフトマスク（実施例１〜３）を使って半導体基板上に微細パターンを形成した場合は、パターン欠陥はなかった。
(Manufacture of semiconductor devices)
Moreover, when a fine pattern was formed on a semiconductor substrate by lithography using a phase shift mask (Comparative Examples 1 to 4) in which these phase defects were confirmed, a pattern defect as a phase defect factor of the phase shift mask was found. When a fine pattern was formed on a semiconductor substrate using a phase shift mask (Examples 1 to 3) that was confirmed but phase defects were not confirmed, there were no pattern defects.
（ＥＵＶ反射型マスクブランクスおよびマスクの製造）
上述の実施例１〜３、比較例１〜４にかかるマスクブランクス用ガラス基板の製造方法によって製造したガラス基板上に、Ｍｏ膜（２．８ｎｍ）とＳｉ膜（４．２ｎｍ）の積層膜を４０周期にわたり形成し、最後にＳｉ膜を４ｎｍ形成して多層反射膜を形成した。次に、キャップ層としてＲｕＮｂ膜を２．５ｎｍ形成した。さらに、ＲｕＮｂ膜上にＴａＢＮ膜からなる吸収体膜を形成してＥＵＶ反射型マスクブランクスを作製した。さらに、ＴａＢＮ膜上にレジスト膜を形成し、パターニングしてレジストパターンとした後、このレジストパターンをマスクにしてＴａＢＮ膜をドライエッチングによりエッチング除去、レジストパターンを除去してＥＵＶ反射型マスクを作製した。
(Manufacture of EUV reflective mask blanks and masks)
On the glass substrate manufactured by the manufacturing method of the glass substrate for mask blanks concerning the above-mentioned Examples 1-3 and Comparative Examples 1-4, the laminated film of Mo film | membrane (2.8 nm) and Si film | membrane (4.2 nm). It was formed over 40 periods, and finally a Si film was formed to 4 nm to form a multilayer reflective film. Next, a RuNb film having a thickness of 2.5 nm was formed as a cap layer. Further, an EUV reflective mask blank was produced by forming an absorber film made of a TaBN film on the RuNb film. Further, after forming a resist film on the TaBN film and patterning it into a resist pattern, the TaBN film was etched away by dry etching using this resist pattern as a mask, and the resist pattern was removed to produce an EUV reflective mask. .
（半導体装置の製造）
上述と同様にしてＥＵＶ反射型マスクブランクスの表面欠陥、ＥＵＶ反射型マスクの位相欠陥、ＥＵＶ反射型マスクを使ってリソグラフィー技術により作製した半導体基板上に形成された微細パターンのパターン欠陥について調べたところ、実施例１〜３のガラス基板を使った場合、上述の欠陥はなかったが、比較例１〜４のガラス基板を使った場合、ＥＵＶ反射型マスクブランクス、ＥＵＶ反射型マスク、半導体装置に上述の欠陥が確認された。
(Manufacture of semiconductor devices)
In the same manner as described above, the surface defects of the EUV reflective mask blanks, the phase defects of the EUV reflective mask, and the pattern defects of the fine pattern formed on the semiconductor substrate produced by lithography using the EUV reflective mask were examined. When the glass substrates of Examples 1 to 3 were used, the above-described defects were not found, but when the glass substrates of Comparative Examples 1 to 4 were used, the EUV reflective mask blanks, EUV reflective masks, and semiconductor devices were described above. The defect was confirmed.
尚、上述の実施例では、遊星歯車方式の両面研磨装置を使って研磨加工を行った例を示したが、これに限らず、他の方式の両面研磨装置や片面ずつ研磨を行う片面研磨装置を使い、コロイダルシリカ砥粒を用いた研磨液により精密研磨しても上述と同様の効果が得られる。
また、上述の実施例では、コロイダルシリカ砥粒を含む研磨液による研磨工程（超精密研磨工程）の前に、酸化セリウム砥粒を含む研磨液による粗研磨工程、精密研磨工程を行なった例をあげたが、これに限定されるものではない。コロイダルシリカ砥粒を含む研磨液による研磨工程を行なう前のガラス基板が十分に平坦で平滑であれば、酸化セリウム砥粒による粗研磨工程及び／又は精密研磨工程を行なわなくてもよい。
また、粗研磨工程、精密研磨工程を行なう場合であっても、酸化セリウム以外に、酸化ジルコニウム、酸化アルミニウム等の研磨砥粒を使用してもかまわない。
In the above-described embodiment, an example in which the polishing process is performed using the planetary gear type double-side polishing apparatus is shown. However, the present invention is not limited to this, and other types of double-side polishing apparatuses and single-side polishing apparatuses that perform polishing one side at a time. The same effect as described above can be obtained even if the substrate is precisely polished with a polishing liquid using colloidal silica abrasive grains.
Moreover, in the above-mentioned Example, the example which performed the rough | crude grinding | polishing process and the precision polishing process by the polishing liquid containing a cerium oxide abrasive grain before the grinding | polishing process (ultra-precision polishing process) by the polishing liquid containing a colloidal silica abrasive grain was performed. Although mentioned, it is not limited to this. If the glass substrate before performing the polishing process with the polishing liquid containing colloidal silica abrasive grains is sufficiently flat and smooth, the rough polishing process and / or the precision polishing process with cerium oxide abrasive grains need not be performed.
Even when a rough polishing process or a precision polishing process is performed, abrasive grains such as zirconium oxide and aluminum oxide may be used in addition to cerium oxide.
本発明は、近年における超ＬＳＩデバイスの高密度化、高精度化にも対応できるように基板表面に高さ数ｎｍ程度の凸状欠陥のないマスクブランクス用ガラス基板及びその製造方法、並びに該基板を用いたマスクブランクス、及びその製造方法、並びに、転写マスク及びその製造方法、及び半導体装置の製造方法を得る際等に利用できる。 The present invention relates to a glass substrate for mask blanks having no convex defects having a height of several nanometers on the substrate surface, a method for manufacturing the same, and the substrate so as to cope with the recent increase in density and accuracy of VLSI devices. The present invention can be used to obtain mask blanks using the semiconductor device, a manufacturing method thereof, a transfer mask, a manufacturing method thereof, and a manufacturing method of a semiconductor device.
１ 両面研磨装置
２ 太陽歯車
３ 内歯歯車
４ キャリア
５ 被研磨加工物（ガラス基板）
６ 研磨パッド
７ 上定盤
８ 下定盤
９ 研磨液供給部
１０ ローダー水槽
１１ 純水循環経路
１２ ポンプ
１３ 紫外線照射手段
１４ フィルタ
１５ 配管
２０ 純水オバーフロー槽
３０ フッ酸＋ケイフッ酸処理槽
３１ フッ酸＋ケイフッ酸処理槽
DESCRIPTION OF SYMBOLS 1 Double-side polish apparatus 2 Sun gear 3 Internal gear 4 Carrier 5 Workpiece to be polished (glass substrate)
6 Polishing pad 7 Upper surface plate 8 Lower surface plate 9 Polishing liquid supply unit 10 Loader water tank 11 Pure water circulation path 12 Pump 13 Ultraviolet irradiation means 14 Filter 15 Pipe 20 Pure water overflow tank 30 Hydrofluoric acid + silicic acid treatment tank 31 Hydrofluoric acid + Silicic acid treatment tank
Claims (9)
前記研磨後の基板を、フッ酸、ケイフッ酸、またはフッ酸及びケイフッ酸を含む洗浄液で処理する洗浄工程を有すると共に、
前記洗浄工程を行う前の基板を保管しておく純水槽内に、紫外線を照射する手段を有しており、
前記洗浄工程を行う前の基板を保管しておく純水槽と、前記洗浄工程を行う洗浄槽との間に、純水処理と、超音波またはメガソニック処理とを組み合わせた処理を行う工程を有する
ことを特徴とするマスクブランクス用ガラス基板の製造方法。 In the manufacturing method of the glass substrate for mask blanks, which has a polishing step of double-side polishing the glass substrate surface for mask blanks using a polishing liquid containing polishing abrasive grains,
And having a cleaning step of treating the polished substrate with hydrofluoric acid, silicic hydrofluoric acid, or a cleaning liquid containing hydrofluoric acid and silicic hydrofluoric acid,
In deionized water tank to keep a previous substrate to perform the cleaning process, and have a means for irradiating ultraviolet rays,
A deionized water tank to keep a previous substrate to perform the cleaning process, between the cleaning tank for performing the washing step, a step of performing a deionized water treatment, the process of combining the ultrasonic or megasonic treatment <br/> A method for producing a glass substrate for mask blanks.
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| JP2014224981A (en) * | 2013-04-25 | 2014-12-04 | 旭硝子株式会社 | Method for cleaning glass substrate for photomask |
| JP6423279B2 (en) * | 2015-02-10 | 2018-11-14 | 株式会社フジミインコーポレーテッド | Polishing composition |
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| JP2600476B2 (en) * | 1990-10-26 | 1997-04-16 | 富士通株式会社 | Pure water production apparatus and semiconductor substrate pure water treatment method |
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