JP4283061B2 - Manufacturing method of glass substrate for electronic device, manufacturing method of mask blanks, and manufacturing method of transfer mask - Google Patents

Manufacturing method of glass substrate for electronic device, manufacturing method of mask blanks, and manufacturing method of transfer mask Download PDF

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JP4283061B2
JP4283061B2 JP2003295565A JP2003295565A JP4283061B2 JP 4283061 B2 JP4283061 B2 JP 4283061B2 JP 2003295565 A JP2003295565 A JP 2003295565A JP 2003295565 A JP2003295565 A JP 2003295565A JP 4283061 B2 JP4283061 B2 JP 4283061B2
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glass substrate
polishing
mask
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polishing pad
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今朝広 小池
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Hoya Corp
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Description

本発明は、基板表面に微小な凸状の表面欠陥のない電子デバイス用ガラス基板(例えば、マスクブランクス用ガラス基板など)、該基板を用いたマスクブランクスの製造方法、及び転写マスクの製造方法に関する。   The present invention relates to a glass substrate for electronic devices (for example, a glass substrate for mask blanks) having no minute convex surface defects on the substrate surface, a method for manufacturing mask blanks using the substrate, and a method for manufacturing a transfer mask. .

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などの電子デバイ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、下記特許文献1(特開昭64−40267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。
上記公報によれば、使用する研磨パッドとしては、基布としての不織布にポリウレタン樹脂を含浸、発泡させたもの等を使用することができるとされ、実施例ではスウェードタイプの研磨パッドを使った例が記載されている。
Due to the recent increase in density and accuracy of VLSI devices, the demands for flatness and surface defects of glass substrates for electronic devices such as glass substrates for mask blanks are becoming stricter year by year. 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 Patent Document 1 (Japanese Patent Laid-Open No. 64-40267). 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.
According to the above publication, as the polishing pad to be used, a nonwoven fabric as a base fabric impregnated with polyurethane resin and foamed can be used, and in the examples, an example using a suede type polishing pad is used. Is described.

上述の研磨パッドは、一般にウレタン樹脂組成物を用いた湿式凝固法によって製造される。この湿式凝固法とは、ウレタン樹脂組成物を調整した後、ウレタン樹脂組成物を支持体に塗布し、次いで、水、ジメチルホルムアミドに、界面活性剤等の分散安定剤、湿式凝固助剤を添加した混合溶液中にて湿式凝固処理を行い、支持体上に発泡層を生成させ、その後乾燥し、最表面をバフして得られる。
また、下記特許文献2(特開2003−94323号公報)には、研磨パッドに含まれる添加剤(界面活性剤)が発泡層に残存されていることで、被研磨部材の研磨において泡が発生し、被研磨部材の品質低下、製品の歩留まりを悪化させることが記載されている。そのため、湿式発泡層を形成する混合溶液中に含まれる界面活性剤の量を減らすか、研磨パッドの界面活性剤の量を後工程で減じた研磨パッドが記載されている。
特開昭64−40267号公報 特開2003−94323号公報
The above-described polishing pad is generally produced by a wet coagulation method using a urethane resin composition. With this wet coagulation method, after preparing the urethane resin composition, the urethane resin composition is applied to a support, and then a dispersion stabilizer such as a surfactant and a wet coagulation aid are added to water and dimethylformamide. A wet coagulation treatment is performed in the mixed solution thus produced to form a foam layer on the support, followed by drying and buffing the outermost surface.
Further, in the following Patent Document 2 (Japanese Patent Application Laid-Open No. 2003-94323), an additive (surfactant) contained in the polishing pad remains in the foamed layer, so that bubbles are generated in polishing the member to be polished. Further, it is described that the quality of the member to be polished is deteriorated and the yield of the product is deteriorated. Therefore, a polishing pad is described in which the amount of the surfactant contained in the mixed solution for forming the wet foam layer is reduced or the amount of the surfactant in the polishing pad is reduced in a subsequent step.
JP-A 64-40267 JP 2003-94323 A

本発明者は、上記研磨パッドとコロイダルシリカを用いて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べた。その結果、上記の従来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〜2000nmの凸状の突起が形成される場合があることを突き止めた。これは、従来の目視検査では確認できない小さい高さの凸状の突起で、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。
この凸状の突起上に薄膜を形成し、マスクブランクス、更にマスクを作製した場合、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以上の欠陥が無いこと、更には0.1μm以上の欠陥が無いこと、また更には0.05μm以上の欠陥が無いことを満たしたとしても、この基板を用いて作製されるマスクブランクス、及びマスクの欠陥検査を行った場合、問題となることがある。
The present inventor has clarified whether the surface of the glass substrate that has been subjected to final polishing using the above-described polishing pad and colloidal silica satisfies a high level requirement for flatness and surface defects that are required in recent years. I investigated. As a result, it was found that a convex protrusion having a height of about several nanometers and a size of several tens of nanometers to 2,000 nanometers may be formed on the surface of the glass substrate that has been finish-polished by the conventional method described above. . This is a convex protrusion with a small height that cannot be confirmed by conventional visual inspection, and it is only for the first time by a defect inspection device developed to confirm the above-mentioned demand for a high level of surface defect freeness that has recently been required. It was confirmed.
When a thin film is formed on this convex projection, and mask blanks and further masks are produced, the size of the convex projection is enlarged, so that a defect of 0.3 μm or more required as the next generation substrate Even if it is satisfied that there is no defect, more than 0.1 μm defect, and further no more than 0.05 μm defect, mask blanks manufactured using this substrate, and mask defect inspection May cause problems.

また、この数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、及び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、凸状の突起による位相角変化が大きくなり(凸状突起の高さが5nmの場合、露光波長がArF(193nm)では、位相角変化は4.6度、F2(157nm)では、位相角変化は5.7度となる)、無視できない問題となる。
また、この数nm程度の凸状の突起が形成されたガラス基板を使って反射型マスクブランクス、及び反射型マスクを作製した場合、マスク面のパターン近傍に凸状突起が存在すると、反射光にはその凸状突起に起因した位相の変化が起こる。この位相の変化は転写されるパターンの位置精度やコントラストを悪化させる原因となる。特に波長が0.2〜100nm程度の極端紫外(Extreme UltraViolet、EUV)光のような短波長の光を露光光として用いる場合、マスク面上の微細な凹凸に対して位相の変化が非常に敏感となるため、転写像への影響が大きくなり、微細な凹凸に由来する位相の変化は無視できない問題となる。例えば、13nm程度のEUV光を用いる場合、2nm程度の凸状突起でさえ位相欠陥となりうる。
In addition, when a phase shift mask blank and a phase shift mask are produced using a glass substrate on which convex projections of about several nanometers are formed, convex projections are produced as the wavelength of exposure light becomes shorter. (If the height of the convex protrusion is 5 nm, the phase angle change is 4.6 degrees when the exposure wavelength is ArF (193 nm), and the phase angle change is 5.7 when F2 (157 nm). It becomes a problem that cannot be ignored.
In addition, when a reflective mask blank and a reflective mask are produced using a glass substrate on which convex projections of about several nm are formed, if convex projections exist in the vicinity of the mask surface pattern, Changes in phase due to the convex protrusions. This change in phase causes the positional accuracy and contrast of the transferred pattern to deteriorate. In particular, when short-wavelength light such as extreme ultraviolet (Extreme UltraViolet, EUV) light having a wavelength of about 0.2 to 100 nm is used as exposure light, the phase change is very sensitive to fine irregularities on the mask surface. Therefore, the influence on the transferred image is increased, and a phase change caused by fine unevenness becomes a problem that cannot be ignored. For example, when EUV light of about 13 nm is used, even convex protrusions of about 2 nm can cause phase defects.

本発明は、上述の問題点に鑑みてなされたものであり、精密研磨を行っても、基板表面に微小な凸状の表面欠陥が発生しないか又は発生率の低い電子デバイス用ガラス基板、及び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、基板表面に微小な凸状の表面欠陥が起因するパターン欠陥のない転写マスクの製造方法を提供することを第二の目的とする。
The present invention has been made in view of the above-mentioned problems, and even if precision polishing is performed, a minute convex surface defect does not occur on the substrate surface or the glass substrate for an electronic device has a low incidence, and It is a first object to provide a method for manufacturing a mask blank.
A second object of the present invention is to provide a method for producing a transfer mask free from pattern defects caused by minute convex surface defects on the substrate surface.

本発明者は、本発明者が突き止めた上記課題を解決するため、従来のコロイダルシリカ砥粒を含む研磨液と研磨パッドを使用して研磨すると、何故凸状の突起が形成されるかを考察した。そして、研磨液の粘性と、研磨パッドに含まれる界面活性剤との関係に着目し、凸状の突起が形成される要因を以下のように推測した。
コロイダルシリカ砥粒を含む研磨液は通常、安定性の点からNaOHやKOH等の無機アルカリや、アミン等の有機アルカリを添加してアルカリ性の研磨液としている。従って、アルカリを添加していない研磨液に比べ研磨液の粘性が高い。
一方、研磨パッドの製造の際に使用する界面活性剤は、一般にある程度の粘性を持っており、研磨パッド中に除去されずに含まれている。
In order to solve the above-mentioned problems found by the present inventor, the present inventor considered why convex protrusions are formed when polishing using a polishing liquid and a polishing pad containing conventional colloidal silica abrasive grains. did. Then, paying attention to the relationship between the viscosity of the polishing liquid and the surfactant contained in the polishing pad, the cause of the formation of convex protrusions was estimated as follows.
A polishing liquid containing colloidal silica abrasive grains is usually made into an alkaline polishing liquid by adding an inorganic alkali such as NaOH or KOH or an organic alkali such as amine from the viewpoint of stability. Accordingly, the viscosity of the polishing liquid is higher than that of the polishing liquid to which no alkali is added.
On the other hand, the surfactant used in the production of the polishing pad generally has a certain degree of viscosity and is contained in the polishing pad without being removed.

従って、上述のコロイダルシリカ砥粒を含む研磨液と、界面活性剤が含有されている研磨パッドを使用してガラス基板を研磨加工すると、研磨加工中にコロイダルシリカ砥粒が凝集体を形成し、ガラス基板に付着する確率が高くなる。
ガラス基板上のある箇所にコロイダルシリカ砥粒の凝集体が停止もしくは付着した状態で研磨工程、さらにアルカリや酸を使った洗浄工程が進むと、その箇所はコロイダルシリカ砥粒の凝集体で被覆された状態となり、凝集体と基板のエッチング速度の差により、微小な凸状の突起が形成されるものと考えられる。尚、上述のような凸状の突起が形成されるメカニズムは、精密研磨に使用するコロイダルシリカ砥粒の場合に確認されることであるが、広くは研磨砥粒とアルカリを添加したアルカリ性の研磨液についても同様のことが言えるものと考えられる。
本発明は、本発明者が以上の解明事実に基づいて更に鋭意検討した結果なされたものであり、以下の構成を有する。
Therefore, when polishing the glass substrate using the polishing liquid containing the above-mentioned colloidal silica abrasive grains and a polishing pad containing a surfactant, the colloidal silica abrasive grains form aggregates during the polishing process, The probability of adhering to the glass substrate increases.
When the agglomeration of colloidal silica abrasive grains stops or adheres to a certain location on the glass substrate, and the cleaning process using an alkali or acid proceeds, the location is covered with agglomerates of colloidal silica abrasive grains. It is considered that minute convex protrusions are formed due to the difference in etching rate between the aggregate and the substrate. Incidentally, the mechanism by which the convex protrusions as described above are formed is to be confirmed in the case of colloidal silica abrasive grains used for precision polishing, but broadly alkaline polishing with addition of abrasive grains and alkali. The same can be said for the liquid.
This invention was made | formed as a result of this inventor's earnest examination based on the above clarification fact, and has the following structures.

(構成1)研磨パッドを貼着した研磨定盤を電子デバイス用ガラス基板に押付け、研磨砥粒を含む研磨液を供給しながら前記研磨定盤と前記ガラス基板とを相対的に移動させて、前記基板表面を精密研磨する工程を有する電子デバイス用ガラス基板の製造方法であって、前記研磨パッドは、前記研磨液と前記研磨パッドに含まれる界面活性剤との反応により、前記研磨砥粒がガラス基板に付着し、微小な凸状の表面欠陥が発生しないように、界面活性剤が除去されており、前記研磨砥粒はコロイダルシリカを含むことを特徴とする電子デバイス用ガラス基板の製造方法。
(構成2)研磨パッドを貼着した研磨定盤を電子デバイス用ガラス基板に押付け、研磨砥粒を含む研磨液を供給しながら前記研磨定盤と前記ガラス基板とを相対的に移動させて、前記基板表面を精密研磨する工程を有する電子デバイス用ガラス基板の製造方法であって、前記ガラス基板の精密研磨を行う前に、前記研磨パッド中に含まれている界面活性剤を除去するとともに、前記研磨砥粒はコロイダルシリカを含むことを特徴とする電子デバイス用ガラス基板の製造方法。
(構成3)研磨パッドを貼着した研磨定盤を電子デバイス用ガラス基板に押付け、研磨砥粒を含む研磨液を供給しながら前記研磨定盤と前記ガラス基板とを相対的に移動させて、前記基板表面を精密研磨する工程を有する電子デバイス用ガラス基板の製造方法であって、前記研磨液の粘度が10cp以下であり、前記研磨砥粒はコロイダルシリカを含むことを特徴とする電子デバイス用ガラス基板の製造方法。
(Configuration 1) The polishing platen with the polishing pad attached is pressed against the glass substrate for an electronic device, and the polishing platen and the glass substrate are relatively moved while supplying a polishing liquid containing polishing abrasive grains. A method of manufacturing a glass substrate for an electronic device, comprising a step of precisely polishing a surface of the substrate, wherein the polishing pad is formed by the reaction of the polishing liquid and a surfactant contained in the polishing pad, whereby the polishing abrasive grains are A method for producing a glass substrate for an electronic device , wherein the surfactant is removed so as not to cause minute convex surface defects attached to the glass substrate, and the abrasive grains contain colloidal silica. .
(Configuration 2) The polishing platen with the polishing pad attached is pressed against the glass substrate for electronic devices, and the polishing platen and the glass substrate are moved relative to each other while supplying a polishing liquid containing polishing abrasive grains. A method for producing a glass substrate for an electronic device, comprising a step of precisely polishing the substrate surface, and before performing the precise polishing of the glass substrate, removing the surfactant contained in the polishing pad , The said abrasive grain contains colloidal silica, The manufacturing method of the glass substrate for electronic devices characterized by the above-mentioned .
(Configuration 3) Pressing the polishing platen with the polishing pad attached thereto against the glass substrate for electronic devices, relatively moving the polishing platen and the glass substrate while supplying a polishing liquid containing polishing abrasive grains, a method of manufacturing a glass substrate for an electronic device having a step of precisely polishing the substrate surface, the electronic device the viscosity of the polishing liquid Ri der less 10 cp, the abrasive grains, characterized in that it comprises a colloidal silica Method for manufacturing glass substrate.

(構成4)前記コロイダルシリカは有機珪素化合物を加水分解することによって得られることを特徴とする構成に記載の電子デバイス用ガラス基板の製造方法。
(構成5)前記基板は、マスクブランクス用ガラス基板であることを特徴とする構成1乃至4の何れかに記載の電子デバイス用ガラス基板の製造方法。
(構成6)構成5に記載の電子デバイス用ガラス基板の製造方法により製造した電子デバイ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の製造方法。
(構成7)構成6に記載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における前記薄膜をパターニングして電子デバイス用ガラス基板の主表面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。
(Structure 4) The said colloidal silica is obtained by hydrolyzing an organosilicon compound, The manufacturing method of the glass substrate for electronic devices of the structure 3 characterized by the above-mentioned.
(Structure 5) The method for producing a glass substrate for an electronic device according to any one of Structures 1 to 4, wherein the substrate is a glass substrate for mask blanks.
(Structure 6) A mask characterized by forming a thin film that causes an optical change with respect to exposure light on the main surface of a glass substrate for electronic devices manufactured by the method for manufacturing a glass substrate for electronic devices according to Structure 5. Blanks manufacturing method.
(Structure 7) A transfer mask characterized in that the thin film in the mask blank obtained by the mask blank manufacturing method according to Structure 6 is patterned to form a thin film pattern on the main surface of the glass substrate for an electronic device. Production method.

本発明によれば、ガラス基板表面の精密研磨に用いる研磨パッドを、研磨液と研磨パッドに含まれる界面活性剤との反応により、研磨砥粒がガラス基板に付着し、微小な凸状の表面欠陥が発生しないように、界面活性剤が除去されているものとするが、ガラス基板表面の精密研磨に用いる研磨パッド中に含まれる界面活性剤を、精密研磨を行う前に除去する、或いは予め除去されていることによって、研磨液に含まれる研磨砥粒(特にコロイダルシリカ砥粒)のガラス基板に付着するのを抑制することができるので、微小な凸状の突起の発生を抑えることができる。
また、研磨パッド中に含まれる界面活性剤を除去する方法として、ダミー基板と水等の溶媒を使用してダミー基板を研磨と同じように加工することにより、研磨パッドの主に表層に存在する界面活性剤を除去し、表層以外には影響を与えずに、容易に界面活性剤を除去することが出来る。
また、本発明によれば、使用する研磨液の粘性が低いことによって、研磨加工中に研磨液に含まれる研磨砥粒(特にコロイダルシリカ砥粒)が凝集してガラス基板に付着するのを抑制することができ、微小な凸状の突起の発生を抑えることができる。
According to the present invention, a polishing pad used for precision polishing of the surface of a glass substrate is adhered to the glass substrate by a reaction between the polishing liquid and a surfactant contained in the polishing pad. It is assumed that the surfactant is removed so as not to cause defects, but the surfactant contained in the polishing pad used for precision polishing of the glass substrate surface is removed before performing precision polishing, or in advance. By removing, it is possible to suppress the polishing abrasive grains (particularly colloidal silica abrasive grains) contained in the polishing liquid from adhering to the glass substrate, and thus it is possible to suppress the generation of minute convex protrusions. .
Further, as a method of removing the surfactant contained in the polishing pad, the dummy substrate is processed in the same manner as polishing using a dummy substrate and a solvent such as water, so that it exists mainly on the surface layer of the polishing pad. The surfactant can be easily removed without affecting other parts than the surface layer.
In addition, according to the present invention, the viscosity of the polishing liquid used is low, so that the abrasive grains (particularly colloidal silica abrasive grains) contained in the polishing liquid are prevented from aggregating and adhering to the glass substrate during the polishing process. And the generation of minute convex protrusions can be suppressed.

また、本発明は、マスクブランクス用ガラス基板の製造に好適であり、中でも位相シフトマスクブランクス用ガラス基板、或いは反射型マスクブランクス用ガラス基板の製造に好適であり、微小な凸状の表面欠陥により発生する位相差変化を抑えることができ、また微小な凸状の表面欠陥により、その上に形成する多層反射膜表面での位相欠陥を抑えることができる。
また、本発明のマスクブランクスの製造方法によれば、本発明によって製造した電子デバイ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により、ガラス基板上に形成された微小な凸状の表面欠陥によるマスクブランクスの欠陥(膜下欠陥)を防止することができる。
また、本発明の転写マスクの製造方法によれば、本発明によって得られたマスクブランクスにおける薄膜をパターニングして電子デバイス用ガラス基板の主表面上に薄膜パターンを形成することにより、基板表面に微小な凸状の表面欠陥が起因する薄膜パターンのパターン欠陥のない転写マスクが得られる。
In addition, the present invention is suitable for manufacturing a mask blank glass substrate, and particularly suitable for manufacturing a phase shift mask blank glass substrate or a reflective mask blank glass substrate. The generated phase difference change can be suppressed, and the phase defects on the surface of the multilayer reflective film formed thereon can be suppressed by the minute convex surface defects.
Moreover, according to the manufacturing method of the mask blank of this invention, on the glass substrate by forming the thin film which brings an optical change with respect to exposure light on the main surface of the glass substrate for electronic devices manufactured by this invention. Mask blank defects (subfilm defects) due to the formed minute convex surface defects can be prevented.
Moreover, according to the manufacturing method of the transfer mask of the present invention, the thin film in the mask blank obtained by the present invention is patterned to form a thin film pattern on the main surface of the glass substrate for electronic devices, thereby forming a microscopic surface on the substrate surface. As a result, a transfer mask free from pattern defects in a thin film pattern caused by a convex surface defect can be obtained.

以下、本発明を実施するための最良の実施形態にかかる電子デバイ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、及び転写マスクの製造方法を詳細に説明する。
なお、以下の説明において、微小な凸状の表面欠陥(以下、単に突起欠陥ともいう)とは、主成分がSiとOとを含む凸状の突起をいい、その高さは2nm〜7nm程度で、大きさは数十nm〜2000nm程度のものをいう。
本発明の実施の形態にかかる電子デバイス用ガラス基板の製造方法は、構成1にあるように、ガラス基板表面の精密研磨に用いる研磨パッドを、研磨液(スラリー)と研磨パッドに含まれる界面活性剤との反応により、研磨砥粒がガラス基板に付着し、微小な凸状の表面欠陥が発生しないように界面活性剤が除去されているものとすることを特徴とする。また、構成2にあるように、電子デバイス用ガラス基板の表面を、研磨砥粒を用いた研磨液(スラリー)による研磨を行う前に、研磨パッド中に含まれている界面活性剤を除去することを特徴とする。
Hereinafter, the manufacturing method of the glass substrate for electronic devices, the manufacturing method of mask blanks, and the manufacturing method of a transfer mask concerning the best embodiment for implementing this invention are demonstrated in detail.
In the following description, a minute convex surface defect (hereinafter also simply referred to as a projection defect) refers to a convex projection whose main component includes Si and O, and its height is about 2 nm to 7 nm. The size is about several tens of nm to 2000 nm.
In the method for producing a glass substrate for an electronic device according to an embodiment of the present invention, the polishing pad used for precision polishing of the surface of the glass substrate is used as the polishing pad (slurry) and the surface activity included in the polishing pad as in Configuration 1. The surfactant is removed so that the abrasive grains adhere to the glass substrate due to the reaction with the agent and fine convex surface defects do not occur. Further, as in Configuration 2, the surface active agent contained in the polishing pad is removed before the surface of the glass substrate for electronic devices is polished with a polishing liquid (slurry) using polishing abrasive grains. It is characterized by that.

本発明者の検討によると、凸状の突起が形成されるのは、コロイダルシリカ砥粒のような研磨砥粒を含む研磨液と、界面活性剤が含有されている研磨パッドを使用してガラス基板を研磨加工すると、研磨加工中に研磨砥粒が凝集体を形成し、ガラス基板に付着することに起因するものと考えられ、研磨パッド中に含まれる界面活性剤を、精密研磨を行う前に除去することによって、研磨砥粒のガラス基板に付着するのを抑制することができるので、微小な凸状の突起の発生を抑えることができる。
本発明の実施の形態において、研磨パッド中に含まれている界面活性剤は、上記ガラス基板表面の精密研磨を行う前に除去されていればよい。従って、精密研磨を行う前に、研磨パッド中に含まれている界面活性剤を除去してもよいし、或いは、研磨パッドの製造過程において、又は研磨パッドの製造後の処理において研磨パッド中に含まれている(残存している)界面活性剤が除去されたものを使用することができる。
研磨パッド中に含まれている界面活性剤が除去された結果、界面活性剤の含有量は略ゼロであることが望ましいが、本発明の作用効果を損わない限りにおいては、極少量の界面活性剤が残存していても構わない。
According to the study of the present inventor, convex protrusions are formed by using a polishing liquid containing polishing abrasive grains such as colloidal silica abrasive grains and a polishing pad containing a surfactant. When the substrate is polished, it is considered that the abrasive grains form aggregates during the polishing process and adhere to the glass substrate, and the surface active agent contained in the polishing pad is removed before precision polishing. Since it can suppress adhering to the glass substrate of a polishing abrasive grain by removing, it can suppress generation | occurrence | production of a micro convex-shaped protrusion.
In the embodiment of the present invention, the surfactant contained in the polishing pad only needs to be removed before performing the precise polishing of the glass substrate surface. Accordingly, the surfactant contained in the polishing pad may be removed before performing the precision polishing, or in the polishing pad during the polishing pad manufacturing process or in the post-manufacturing processing of the polishing pad. Those from which the contained (remaining) surfactant is removed can be used.
As a result of the removal of the surfactant contained in the polishing pad, it is desirable that the surfactant content is substantially zero. However, as long as the effects of the present invention are not impaired, a very small amount of the interface is required. The activator may remain.

研磨パッド中に含まれる界面活性剤は、例えば、PL−210(花王株式会社製商品名グリセリンエチレンオキシドポリオキシド化合物)等が使用されている。この界面活性剤を研磨パッドから除去する方法としては、水や有機溶媒などの溶液に浸漬して溶出させて除去する方法や、水や有機溶媒などの溶液を研磨パッドに吹き付けて除去する方法や、ダミー基板を準備し、溶媒を供給しながら研磨パッドにダミー基板を押付け、互いに回転させることで研磨パッド中に含まれている界面活性剤を除去する方法がある。本発明に関与する界面活性剤は、研磨パッドでも微細な開口が形成された表層に存在しているものであること、研磨パッドの表層以外には影響を与えない方が好ましいことなどから、ダミー基板を準備し、溶媒を供給しながら研磨パッドにダミー基板を押付け、互いに回転させることで研磨パッド中に含まれている界面活性剤を除去する方法が好ましい。なおこの方法は、精密研磨を行う前にダミー基板をセットして、水や有機溶媒などの溶液を供給し(掛け捨て)ながら通常の研磨と同じようにダミー基板を研磨加工することにより容易に界面活性剤を研磨パッドから除去することができる。研磨パッド中に含まれる界面活性剤は、ダミー基板の研磨加工中に発生する泡として観察される。従って、この泡が観察されなくなるまで、ダミー基板の研磨加工を行って研磨パッド中に含まれる界面活性剤を除去する。   As the surfactant contained in the polishing pad, for example, PL-210 (trade name glycerin ethylene oxide polyoxide compound manufactured by Kao Corporation) is used. As a method of removing this surfactant from the polishing pad, a method of removing it by immersing it in a solution of water or an organic solvent and removing it, a method of removing a solution of water or an organic solvent by spraying it on the polishing pad, There is a method of preparing a dummy substrate, pressing the dummy substrate against the polishing pad while supplying a solvent, and rotating the mutual to remove the surfactant contained in the polishing pad. Since the surfactant involved in the present invention is present in the surface layer in which a fine opening is formed even in the polishing pad, it is preferable not to affect other than the surface layer of the polishing pad. A method of removing the surfactant contained in the polishing pad by preparing the substrate, pressing the dummy substrate against the polishing pad while supplying the solvent, and rotating the substrate against each other is preferable. This method can be easily performed by setting the dummy substrate before precision polishing and polishing the dummy substrate in the same manner as normal polishing while supplying (dispersing) a solution such as water or an organic solvent. The surfactant can be removed from the polishing pad. The surfactant contained in the polishing pad is observed as bubbles generated during polishing of the dummy substrate. Accordingly, the dummy substrate is polished until the bubbles are no longer observed to remove the surfactant contained in the polishing pad.

ダミー基板は、精密研磨で研磨される基板の材料と同じにすることが好ましい。精密研磨で研磨される基板の材料(ガラス)と違う材料にした場合、異物として残り精密研磨工程で傷等の欠陥を引き起こす可能性が高くなるからである。また、研磨パッド中に含まれる界面活性剤の除去効率の観点から、ダミー基板の表面は荒れている方が良いが、荒れすぎると研磨パッドの表層状態を変化、劣化、悪化させることになり、好ましくはダミー基板の表面粗さは、平均表面粗さRaで0.1〜1nm、さらに好ましくは、0.2〜0.5nmとすることが望ましい。   The dummy substrate is preferably made of the same material as the substrate to be polished by precision polishing. This is because, when a material different from the material (glass) of the substrate to be polished by precision polishing is left as a foreign substance, there is a high possibility of causing defects such as scratches in the precision polishing process. In addition, from the viewpoint of the removal efficiency of the surfactant contained in the polishing pad, the surface of the dummy substrate should be rough, but if it is too rough, the surface state of the polishing pad will change, deteriorate, and deteriorate, The surface roughness of the dummy substrate is preferably 0.1 to 1 nm, more preferably 0.2 to 0.5 nm in terms of the average surface roughness Ra.

また、本発明の実施の形態にかかる電子デバイス用ガラス基板の製造方法は、構成3にあるように、上記研磨砥粒を含む研磨液の粘度が10cp以下(但し研磨砥粒と混ぜる溶媒の粘度以上であって)であることを特徴とする。研磨液の粘性が低いことによって、研磨加工中に研磨砥粒(例えばコロイダルシリカ砥粒)が凝集してガラス基板に付着するのを抑制することができ、微小な凸状の突起の発生を抑えることができる。
研磨砥粒がコロイダルシリカ砥粒を含む研磨液である場合には、コロイダルシリカ砥粒を含む粘性の低い研磨液とする方法としては、たとえばアルカリを含まない中性域で使用することができるコロイダルシリカとすることが好ましい。中性域のコロイダルシリカは、蒸留精製が可能な有機珪素化合物を加水分解することで得られ、中性域でしかもNaやK等のアルカリ金属の少ない高純度なコロイダルシリカを得ることが可能である。
なお、以上の粘性の低い研磨液を使用する場合において、研磨パッド中に含まれる界面活性剤の量は出来るだけ少ない方がより望ましい。
尚、以上の実施の形態においては、ガラス基板の材料は特に限定されない。ガラス基板の材料としては、例えば、合成石英ガラス、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、以上の実施の形態における精密研磨は、両面研磨、片面研磨のどちらでも構わない。
Further, in the method for producing a glass substrate for an electronic device according to an embodiment of the present invention, the viscosity of the polishing liquid containing the abrasive grains is 10 cp or less (however, the viscosity of the solvent mixed with the abrasive grains is as described in Configuration 3). That is the above. Due to the low viscosity of the polishing liquid, it is possible to suppress agglomeration of abrasive grains (for example, colloidal silica abrasive grains) during the polishing process and adhere to the glass substrate, thereby suppressing the occurrence of minute convex protrusions. be able to.
When the polishing abrasive is a polishing liquid containing colloidal silica abrasive grains, as a method of making a low-viscosity polishing liquid containing colloidal silica abrasive grains, for example, colloidal that can be used in a neutral region not containing alkali Silica is preferred. Colloidal silica in the neutral range is obtained by hydrolyzing an organosilicon compound that can be purified by distillation, and it is possible to obtain high-purity colloidal silica in the neutral range and with few alkali metals such as Na and K. is there.
In the case of using the above-mentioned low-viscosity polishing liquid, it is more desirable that the amount of the surfactant contained in the polishing pad is as small as possible.
In the above embodiment, the material of the glass substrate is not particularly limited. Examples of the material for the glass substrate include synthetic quartz glass, borosilicate glass, aluminosilicate glass, aluminoborosilicate glass, soda lime glass, and alkali-free glass.
Further, the precision polishing in the above embodiments may be either double-side polishing or single-side polishing.

また、構成5にあるように、電子デバイス用ガラス基板はマスクブランクス用ガラス基板とする。この場合、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、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。
また、構成5にかかる基板は、位相シフトマスクブランクス用ガラス基板か、反射型マスクブランクス用ガラス基板の何れかとすると好適である。上述の通り、本発明の実施の形態にかかる電子デバイス用ガラス基板の製造方法は、微小な凸状の表面欠陥により発生する位相差変化を抑えることができること、微小な凸状の表面欠陥により、その上に形成する多層反射膜表面での位相欠陥を抑えることができることから位相シフトマスクブランクス用ガラス基板、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。
Moreover, as in the structure 5, the glass substrate for electronic devices shall be a glass substrate for mask blanks. In this case, photomask blanks, phase shift mask blanks, reflective mask blanks and the like are listed as mask blanks. LSI (semiconductor integrated circuit) mask blanks, LCD (liquid crystal display) mask blanks and the like are used as mask blanks. Can be mentioned.
Further, the substrate according to Configuration 5 is preferably a glass substrate for phase shift mask blanks or a glass substrate for reflection mask blanks. As described above, the method for manufacturing a glass substrate for an electronic device according to an embodiment of the present invention can suppress a change in phase difference caused by a minute convex surface defect, Since the phase defect on the surface of the multilayer reflective film formed thereon can be suppressed, the glass substrate for phase shift mask blanks and the glass substrate for reflective mask blanks are particularly effective.

また、構成6にあるように、構成5にかかる電子デバイス用ガラス基板の製造方法によって製造した電子デバイ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の製造方法により、ガラス基板上に形成された微小な凸状の表面欠陥によるマスクブランクスの欠陥(膜下欠陥)を防止することができる。
ここで、露光光に対し光学的変化をもたらす薄膜とは、露光光の位相を変化させる位相シフト膜(多層の場合を含む)、露光光を遮断する遮光膜(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)、露光光を反射する反射膜、露光光を吸収する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ス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スのほか、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ス、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。
尚、本発明でいうマスクブランクスは、上述の薄膜以外に、薄膜上にレジスト膜等を形成しても構わない。
Further, as in Configuration 6, forming a thin film that causes an optical change with respect to exposure light on the main surface of the glass substrate for electronic devices manufactured by the method for manufacturing a glass substrate for electronic devices according to Configuration 5 According to the mask blank manufacturing method, defects of the mask blank (subfilm defects) due to minute convex surface defects formed on the glass substrate can be prevented.
Here, the thin film that optically changes the exposure light means a phase shift film (including a multilayer) that changes the phase of the exposure light, a light shielding film (including a multilayer) that blocks the exposure light, or A film in which a phase shift film and a light shielding film are laminated, a halftone film having a phase shift function and a light shielding function (including a case of multilayers), a reflective film that reflects exposure light, an absorber film that absorbs exposure light, etc. Point to. Therefore, the mask blank referred to in the present invention is used in a broad sense, in addition to a photomask blank in which only a light-shielding film is formed, a phase shift mask blank in which a phase shift film, a halftone film, etc. are formed, and a reflection film. A reflective mask blank on which an absorber film or the like is formed is included.
In the mask blank referred to in the present invention, a resist film or the like may be formed on the thin film in addition to the above-described thin film.

また、構成7にあるように、構成6にかかる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における前記薄膜をパターニングして電子デバイス用ガラス基板の主表面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により、基板表面に微小な凸状の表面欠陥が起因する薄膜パターンのパターン欠陥(位相シフトマスクにおいては、位相角が所望の値から外れる位相角欠陥や、反射型マスクにおいては、多層反射膜表面での位相欠陥)のない転写マスクが得られる。薄膜パターンの形成は、レジスト膜付きマスクブランクスを準備し、フォトリソ工程によりレジストパターンを形成し、このレジストパターンをマスクとして薄膜をエッチングすることにより薄膜パターンを形成することができる。   Further, as in Configuration 7, the thin film in the mask blank obtained by the mask blank manufacturing method according to Configuration 6 is patterned to form a thin film pattern on the main surface of the glass substrate for electronic devices. Pattern mask defects caused by minute convex surface defects on the substrate surface (in phase shift masks, phase angle defects whose phase angle deviates from a desired value, or in reflective masks) Can obtain a transfer mask free of phase defects on the surface of the multilayer reflective film. The thin film pattern can be formed by preparing a mask blank with a resist film, forming a resist pattern by a photolithography process, and etching the thin film using the resist pattern as a mask.

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、電子デバイ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、EUV反射型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。
まず、以下の実施例において精密研磨で使用する遊星歯車方式の両面研磨装置について図1を用いて説明する。
遊星歯車方式の両面研磨装置は、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1を研磨パッド7が貼着された挟持可能な上定盤5及び下定盤6と、上定盤5と下定盤6との間に研磨液を供給する研磨液供給部(図示せず)とを備えている。
精密研磨加工時には、キャリア4に保持された被研磨加工物1を上定盤5及び下定盤6とで挟持するとともに、上下定盤5,6の研磨パッド7と被研磨加工物1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1の上下両面が精密研磨加工される。
Hereinafter, based on an Example, this invention is demonstrated more concretely. In the following examples, a glass substrate for phase shift mask blanks and a glass substrate for EUV reflective mask blanks (hereinafter simply referred to as glass substrates) will be described as examples of glass substrates for electronic devices.
First, a planetary gear type double-side polishing apparatus used for precision polishing in the following embodiments will be described with reference to FIG.
The planetary gear type double-side polishing apparatus is engaged with the sun gear 2, the 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. The carrier 4 that revolves and rotates according to the rotation, the upper surface plate 5 and the lower surface plate 6 that can hold the workpiece 1 held by the carrier 4 to which the polishing pad 7 is attached, and the upper surface plate 5. And a lower surface plate 6 are provided with a polishing liquid supply unit (not shown) for supplying a polishing liquid.
At the time of precision polishing, the workpiece 1 held by the carrier 4 is sandwiched between the upper surface plate 5 and the lower surface plate 6, and between the polishing pad 7 of the upper and lower surface plates 5, 6 and the workpiece 1 to be polished. While supplying the polishing liquid, the upper and lower surfaces of the workpiece 1 are precisely polished while the carrier 4 revolves and rotates according to the rotation of the sun gear 2 and the internal gear 3.

本実施例は、実施の形態にかかる電子デバイス用ガラス基板の製造方法の具体例である。
合成石英ガラス基板(152mm×152mm)の端面を面取加工、及び研削加工、更に酸化セリウム砥粒を含む研磨液で粗研磨処理を終えたガラス基板を準備した。
精密研磨で使用する両面研磨装置の上下定盤に新品の研磨パッドを貼着し、電子デバイス用ガラス基板と同じ材料で同じ大きさのダミー基板(平均表面粗さRaが0.5nm程度)をキャリアにセットし、以下の条件で研磨パッドに含まれる界面活性剤の除去を行った。研磨パッドは、従来のウレタン樹脂組成物を用いた湿式凝固法によって製造されたものを使用する。
溶媒:水(掛け捨て)
研磨パッド:超軟質ポリシャ(スウェードタイプ)
加工圧力:100g/cm
尚、研磨パッドに含まれる界面活性剤の除去は、目視にて泡が見えなくなるまでダミー基板の加工を行った。
キャリアからダミー基板を取り外し、ジェットスプレーにて研磨パッドの表層に付着した異物を除去した。
This example is a specific example of the method for manufacturing the glass substrate for electronic devices according to the embodiment.
A glass substrate was prepared in which the end face of a synthetic quartz glass substrate (152 mm × 152 mm) was chamfered and ground, and further subjected to rough polishing with a polishing liquid containing cerium oxide abrasive grains.
A new polishing pad is attached to the upper and lower surface plates of a double-side polishing machine used in precision polishing, and a dummy substrate (average surface roughness Ra is about 0.5 nm) of the same material and size as the glass substrate for electronic devices. It was set on a carrier, and the surfactant contained in the polishing pad was removed under the following conditions. A polishing pad manufactured by a wet coagulation method using a conventional urethane resin composition is used.
Solvent: Water (throw away)
Polishing pad: Super soft polisher (suede type)
Processing pressure: 100 g / cm 2
The removal of the surfactant contained in the polishing pad was performed by processing the dummy substrate until no bubbles were visible.
The dummy substrate was removed from the carrier, and foreign matter adhering to the surface layer of the polishing pad was removed by jet spray.

次に、予め準備しておいた合成石英ガラス基板(152mm×152mm)の端面を面取加工、及び研削加工、更に酸化セリウム砥粒を含む研磨液で粗研磨処理を終えたガラス基板を上述の両面研磨装置のキャリアにセットし、以下の研磨条件で精密研磨を行った。
研磨液:コロイダルシリカ砥粒(平均粒径100nm)を含むアルカリ水溶液
加工圧力:50〜100g/cm
加工時間:30〜90min
精密研磨終了後、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、希フッ酸水溶液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。
上述の精密研磨を複数バッチ行い、精密研磨を施したガラス基板(位相シフトマスクブランクス用ガラス基板)を1000枚作製した。
Next, the end surface of the synthetic quartz glass substrate (152 mm × 152 mm) prepared in advance is chamfered and ground, and the glass substrate that has been subjected to rough polishing treatment with a polishing liquid containing cerium oxide abrasive grains is used as described above. It was set on a carrier of a double-side polishing apparatus and precision polishing was performed under the following polishing conditions.
Polishing liquid: Alkaline aqueous solution containing colloidal silica abrasive grains (average particle diameter 100 nm) Processing pressure: 50 to 100 g / cm 2
Processing time: 30 ~ 90min
After the precision polishing was completed, in order to remove the abrasive grains adhering to the glass substrate, the glass substrate was immersed in a cleaning tank containing a cleaning solution containing a dilute hydrofluoric acid solution (applied with ultrasonic waves) for cleaning.
A plurality of batches of the above-described precision polishing were performed to prepare 1000 glass substrates (glass substrates for phase shift mask blanks) subjected to the precision polishing.

この得られたガラス基板の主表面の表面粗さは、全て二乗平均平方根粗さ(RMS)で0.15nm以下と良好であった。
また、この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高さ数nm程度(約2nm〜7nm)の微小な凸状の表面欠陥を調べたところ、1000枚中4枚のガラス基板で確認された。つまり、微小な凸状の表面欠陥の発生率は0.4%であった。
The surface roughness of the main surface of the obtained glass substrate was as good as 0.15 nm or less in terms of root mean square roughness (RMS).
Further, when the main surface of the obtained glass substrate was examined for a minute convex surface defect having a height of about several nm (about 2 nm to 7 nm) using a defect inspection apparatus using a laser interference confocal optical system, 1000 It was confirmed with 4 glass substrates. That is, the incidence of minute convex surface defects was 0.4%.

上述の実施例1において、精密研磨で使用する研磨液を、中性(pH:7〜7.6)のコロイダルシリカ(平均粒径30〜200nm)を含む水溶液にした以外は、実施例1と同様にしてガラス基板(位相シフトマスクブランクス用ガラス基板)1000枚を作製した。
この得られたガラス基板の主表面の表面粗さは、全て二乗平均平方根粗さ(RMS)で0.15nm以下と良好であった。
また、この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高さ数nm程度(約2nm〜7nm)の微小な凸状の表面欠陥を調べたところ、1000枚中1枚のガラス基板で確認された。つまり、微小な凸状の表面欠陥の発生率は0.1%であった。
In Example 1 described above, Example 1 and Example 1 were used except that the polishing liquid used for precision polishing was an aqueous solution containing neutral (pH: 7 to 7.6) colloidal silica (average particle size: 30 to 200 nm). Similarly, 1000 glass substrates (glass substrates for phase shift mask blanks) were produced.
The surface roughness of the main surface of the obtained glass substrate was all good as 0.15 nm or less in root mean square roughness (RMS).
Further, when the main surface of the obtained glass substrate was examined for a minute convex surface defect having a height of about several nm (about 2 nm to 7 nm) using a defect inspection apparatus using a laser interference confocal optical system, 1000 It was confirmed on one of the glass substrates. That is, the incidence of minute convex surface defects was 0.1%.

上述の実施例1において、精密研磨で使用する研磨液を、コロイダルシリカ砥粒の種類と、アルカリのpHを調整して粘度を8cpにして、精密研磨前のダミー基板による研磨パッド中に含まれる界面活性剤の除去は行わなかったこと以外は、実施例1と同様にしてガラス基板(位相シフトマスクブランクス用ガラス基板)1000枚を作製した。
この得られたガラス基板の主表面の表面粗さは、全て二乗平均平方根粗さ(RMS)で0.15nm以下と良好であった。
また、この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高さ数nm程度(約2nm〜7nm)の微小な凸状の表面欠陥を調べたところ、1000枚中3枚のガラス基板で確認された。つまり、微小な凸状の表面欠陥の発生率は0.3%であった。
In Example 1 described above, the polishing liquid used for precision polishing is contained in the polishing pad by the dummy substrate before precision polishing by adjusting the pH of the colloidal silica abrasive grains and the pH of the alkali to 8 cp. 1000 glass substrates (glass substrates for phase shift mask blanks) were produced in the same manner as in Example 1 except that the surfactant was not removed.
The surface roughness of the main surface of the obtained glass substrate was as good as 0.15 nm or less in terms of root mean square roughness (RMS).
Further, when the main surface of the obtained glass substrate was examined for a minute convex surface defect having a height of about several nm (about 2 nm to 7 nm) using a defect inspection apparatus using a laser interference confocal optical system, 1000 It was confirmed on 3 glass substrates. That is, the incidence of minute convex surface defects was 0.3%.

(比較例1)
上述の実施例1において、精密研磨前のダミー基板による研磨パッド中に含まれる界面活性剤の除去を行わなかった以外は、実施例1と同様にしてガラス基板(位相シフトマスクブランクス用ガラス基板)1000枚を作製した。
この得られたガラス基板の主表面の表面粗さは、全て二乗平均平方根粗さ(RMS)で0.15nm以下と良好であったが、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高さ数nm程度(約2nm〜7nm)の微小な凸状の表面欠陥を調べたところ、1000枚中57枚のガラス基板で確認された。つまり、微小な凸状の表面欠陥の発生率は5.7%と高かった。
(Comparative Example 1)
In the above-described Example 1, a glass substrate (glass substrate for phase shift mask blanks) was obtained in the same manner as in Example 1 except that the surfactant contained in the polishing pad by the dummy substrate before precision polishing was not removed. 1000 sheets were produced.
The surface roughness of the main surface of the obtained glass substrate was all good in terms of root mean square roughness (RMS) of 0.15 nm or less, but it was high using a defect inspection apparatus using a laser interference confocal optical system. When a minute convex surface defect of about several nm (about 2 nm to 7 nm) was examined, it was confirmed on 57 out of 1000 glass substrates. That is, the incidence of minute convex surface defects was as high as 5.7%.

上述の実施例1において、ガラス基板の材料をSiO−TiO系低熱膨張ガラス基板(152mm×152mm)に変えた以外は、実施例1と同様にしてガラス基板(EUV反射型マスクブランクス用ガラス基板)1000枚を作製した。
この得られたガラス基板の主表面の表面粗さは、全て二乗平均平方根粗さ(RMS)で0.15nm以下と良好であった。
また、この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高さ数nm程度(約2nm〜7nm)の微小な凸状の表面欠陥を調べたところ、1000枚中9枚のガラス基板で確認された。つまり、微小な凸状の表面欠陥の発生率は0.9%であった。
A glass substrate (glass for EUV reflective mask blanks) was prepared in the same manner as in Example 1 except that the material of the glass substrate in Example 1 was changed to a SiO 2 —TiO 2 low thermal expansion glass substrate (152 mm × 152 mm). Substrate) 1000 sheets were produced.
The surface roughness of the main surface of the obtained glass substrate was as good as 0.15 nm or less in terms of root mean square roughness (RMS).
Further, when the main surface of the obtained glass substrate was examined for a minute convex surface defect having a height of about several nm (about 2 nm to 7 nm) using a defect inspection apparatus using a laser interference confocal optical system, 1000 It was confirmed on 9 glass substrates. That is, the incidence of minute convex surface defects was 0.9%.

(比較例2)
上述の実施例4において、精密研磨前のダミー基板による研磨パッド中に含まれる界面活性剤の除去を行わなかった以外は、実施例1と同様にしてガラス基板(EUV反射型マスクブランクス用ガラス基板)1000枚を作製した。
この得られたガラス基板の主表面の表面粗さは、全て二乗平均平方根粗さ(RMS)で0.15nm以下と良好であったが、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高さ数nm程度(約2nm〜7nm)の微小な凸状の表面欠陥を調べたところ、1000枚中112枚のガラス基板で確認された。つまり、微小な凸状の表面欠陥の発生率は11.2%と非常に高かった。
尚、上述の実施例1〜4及び比較例1、2で確認された微小な凸状の表面欠陥をEPMA(ElectronProbe(X-ray) Micro Analyzer)で成分分析を行ったところ、主成分がSi、Oを含むものであることが確認された。
(Comparative Example 2)
In Example 4 above, a glass substrate (glass substrate for EUV reflective mask blanks) was used in the same manner as Example 1 except that the surfactant contained in the polishing pad was not removed by the dummy substrate before precision polishing. ) 1000 sheets were produced.
The surface roughness of the main surface of the obtained glass substrate was all good in terms of root mean square roughness (RMS) of 0.15 nm or less, but it was high using a defect inspection apparatus using a laser interference confocal optical system. When a minute convex surface defect of about several nanometers (about 2 nm to 7 nm) was examined, it was confirmed on 112 out of 1000 glass substrates. That is, the incidence of minute convex surface defects was very high at 11.2%.
In addition, when the component analysis was performed for the minute convex surface defects confirmed in Examples 1 to 4 and Comparative Examples 1 and 2 using an EPMA (ElectronProbe (X-ray) Micro Analyzer), the main component was Si. , O was confirmed.

上述の実施例1〜3にかかる電子デバイス用ガラス基板の製造方法によって製造した微小な凸状の表面欠陥のない位相シフトマスクブランクス用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後、レジスト膜を形成して位相シフトマスクブランクスを作製した。
さらに、レジスト膜を所定の描画、現像により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としてモリブデンシリサイド窒化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位相シフトマスクを作製した。
(比較例3)
上述の比較例1の製造方法によって製造した微小な凸状の表面欠陥のある位相シフトマスクブランクス用ガラス基板の一主表面上に実施例5と同様にして成膜を行い、位相シフトマスクブランクスを作製し、さらにこのマスクブランクスから位相シフトマスクを作製した。
A half made of a molybdenum silicide nitride film on one main surface of a glass substrate for phase shift mask blanks having no fine convex surface defects produced by the method for producing a glass substrate for electronic devices according to the above-described Examples 1 to 3. After the tone film was formed by sputtering, a resist film was formed to produce a phase shift mask blank.
Further, the resist film was patterned by predetermined drawing and development to form a resist pattern, and then using this resist pattern as a mask, the molybdenum silicide nitride film was etched away by dry etching, and the resist pattern was removed to prepare a phase shift mask.
(Comparative Example 3)
Film formation was carried out in the same manner as in Example 5 on one main surface of a glass substrate for phase shift mask blanks having a minute convex surface defect produced by the production method of Comparative Example 1 described above. Further, a phase shift mask was produced from this mask blank.

また、上述の実施例4にかかる電子デバイス用ガラス基板の製造方法によって製造した微小な凸状の表面欠陥のないEUV反射型マスクブランクス用ガラス基板の一主表面上に、Mo膜とSi膜の交互積層膜を40周期にわたり形成して多層反射膜を形成し、さらに、多層反射膜上にTaBN膜からなる吸収体膜を形成し、レジスト膜を形成してEUV反射型マスクブランクスを作製した。
さらに、レジスト膜を所定の描画、現像により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。
(比較例4)
上述の比較例2の製造方法によって製造した微小な凸状の表面欠陥のあるEUV反射型マスクブランクス用ガラス基板の一主表面上に実施例6と同様にして成膜を行い、EUV反射型マスクブランクスを作製し、さらにこのマスクブランクスからEUV反射型マスクを作製した。
Moreover, on one main surface of the glass substrate for EUV reflective mask blanks without the micro convex surface defect manufactured with the manufacturing method of the glass substrate for electronic devices concerning the above-mentioned Example 4, Mo film | membrane and Si film | membrane An alternating laminated film was formed over 40 periods to form a multilayer reflective film, an absorber film made of a TaBN film was formed on the multilayer reflective film, and a resist film was formed to produce an EUV reflective mask blank.
Further, the resist film was patterned by predetermined drawing and development to form a resist pattern. Then, using this resist pattern as a mask, the TaBN film was etched away by dry etching, and the resist pattern was removed to produce an EUV reflective mask.
(Comparative Example 4)
An EUV reflective mask was formed in the same manner as in Example 6 on one main surface of a glass substrate for EUV reflective mask blanks having a minute convex surface defect manufactured by the manufacturing method of Comparative Example 2 described above. Blanks were produced, and an EUV reflective mask was produced from the mask blanks.

(評価結果)
こうして作製した位相シフトマスクブランクス、位相シフトマスク、EUV反射型マスクブランクス、EUV反射型マスクの欠陥検査を行ったところ、実施例1〜4にかかる電子デバイス用ガラス基板を用いて製造した位相シフトマスクブランクス、及び位相シフトマスク、並びにEUV反射型マスクブランクス、及びEUV反射型マスクには凸状の表面欠陥が認められなかった。これに対し、微小な凸状の表面欠陥が確認された比較例1、2にかかる電子デバイス用ガラス基板を用いて製造した位相シフトマスクブランクス、及び位相シフトマスク、並びにEUV反射型マスクブランクス、及び反射型マスクには、ガラス基板表面、ハーフトーン膜パターンの境界、多層反射膜表面、吸収体膜パターンの境界に凸状の表面欠陥が確認された。これらの表面欠陥は、マスクを用いてパターン転写を行った際の転写像のパターン精度等にも影響を及ぼす。
(Evaluation results)
When the defect inspection of the phase shift mask blanks, phase shift masks, EUV reflective mask blanks, and EUV reflective masks thus manufactured was performed, the phase shift masks manufactured using the glass substrates for electronic devices according to Examples 1 to 4 were used. No convex surface defects were observed in the blanks, the phase shift mask, the EUV reflective mask blanks, and the EUV reflective mask. In contrast, phase shift mask blanks and phase shift masks manufactured using the glass substrates for electronic devices according to Comparative Examples 1 and 2 in which minute convex surface defects were confirmed, and EUV reflective mask blanks, and In the reflective mask, convex surface defects were confirmed on the glass substrate surface, the boundary of the halftone film pattern, the surface of the multilayer reflective film, and the boundary of the absorber film pattern. These surface defects also affect the pattern accuracy of the transferred image when pattern transfer is performed using a mask.

精密研磨工程で使用する遊星歯車方式の両面研磨装置の概略構成を示す断面図である。It is sectional drawing which shows schematic structure of the double-side polish apparatus of the planetary gear system used in a precision grinding | polishing process.

符号の説明Explanation of symbols

1 被研磨加工物
2 太陽歯車
3 内歯歯車
4 キャリア
5 上定盤
6 下定盤
7 研磨パッド
1 Workpiece 2 Sun gear 3 Internal gear 4 Carrier 5 Upper surface plate 6 Lower surface plate 7 Polishing pad

Claims (5)

研磨パッドを貼着した研磨定盤をマスクブランクス用ガラス基板に押付け、研磨砥粒を含む研磨液を供給しながら前記研磨定盤と前記ガラス基板とを相対的に移動させて、前記基板表面を精密研磨する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であって、
前記精密研磨後にアルカリや酸を使った洗浄工程を含み、
前記マスクブランクス用ガラス基板は、位相シフトマスクブランクス用ガラス基板、又はEUV反射型マスクブランクス用ガラス基板の何れかであって、
前記精密研磨に用いる新品の研磨パッドは、前記研磨液と前記研磨パッドに含まれる界面活性剤との反応により、前記研磨砥粒がガラス基板に付着し、微小な凸状の表面欠陥による位相欠陥が発生しないように、界面活性剤が除去されており、前記研磨砥粒はコロイダルシリカを含む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。
The polishing platen with the polishing pad attached is pressed against the glass substrate for mask blanks, and the polishing platen and the glass substrate are moved relative to each other while supplying the polishing liquid containing the abrasive grains, and the substrate surface is moved. A method for producing a glass substrate for mask blanks having a step of precision polishing,
Including a cleaning step using alkali or acid after the precision polishing,
The mask blank glass substrate is either a phase shift mask blank glass substrate or an EUV reflective mask blank glass substrate,
The new polishing pad used for the precision polishing has a phase defect caused by a minute convex surface defect due to the polishing abrasive particles adhering to the glass substrate due to a reaction between the polishing liquid and a surfactant contained in the polishing pad. The method for producing a glass substrate for mask blanks, wherein the surfactant is removed so that no occurrence of erosion occurs and the abrasive grains contain colloidal silica.
研磨パッドを貼着した研磨定盤をマスクブランクス用ガラス基板に押付け、研磨砥粒を含む研磨液を供給しながら前記研磨定盤と前記ガラス基板とを相対的に移動させて、前記基板表面を精密研磨する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であって、
前記精密研磨後にアルカリや酸を使った洗浄工程を含み、
前記マスクブランクス用ガラス基板は、位相シフトマスクブランクス用ガラス基板、又はEUV反射型マスクブランクス用ガラス基板の何れかであって、
新品の研磨パッドを用いて前記ガラス基板の精密研磨を行う前に、微小な凸状の表面欠陥による位相欠陥が発生しない程度、前記研磨パッド中に含まれている界面活性剤を除去するとともに、前記研磨砥粒はコロイダルシリカを含む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。
The polishing platen with the polishing pad attached is pressed against the glass substrate for mask blanks, and the polishing platen and the glass substrate are moved relative to each other while supplying the polishing liquid containing the abrasive grains, and the substrate surface is moved. A method for producing a glass substrate for mask blanks having a step of precision polishing,
Including a cleaning step using alkali or acid after the precision polishing,
The mask blank glass substrate is either a phase shift mask blank glass substrate or an EUV reflective mask blank glass substrate,
Before performing the precise polishing of the glass substrate using a new polishing pad, to the extent that phase defects due to minute convex surface defects do not occur, remove the surfactant contained in the polishing pad, The method for producing a glass substrate for mask blanks, wherein the abrasive grains contain colloidal silica.
前記コロイダルシリカは有機珪素化合物を加水分解することによって得られることを特徴とする請求項1又は2に記載のマスクブランクス用ガラス基板の製造方法。   The said colloidal silica is obtained by hydrolyzing an organosilicon compound, The manufacturing method of the glass substrate for mask blanks of Claim 1 or 2 characterized by the above-mentioned. 請求項1乃至3の何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により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マスクブランクスの製造方法。   A thin film that optically changes 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 claims 1 to 3. A method for manufacturing mask blanks. 請求項4に記載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における前記薄膜をパターニングしてマスクブランクス用ガラス基板の主表面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。   A method for producing a transfer mask, comprising: patterning the thin film in a mask blank obtained by the method for producing a mask blank according to claim 4 to form a thin film pattern on a main surface of a glass substrate for mask blanks.
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Cited By (1)

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Publication number Priority date Publication date Assignee Title
EP2338849A1 (en) 2009-12-28 2011-06-29 Shin-Etsu Chemical Co., Ltd. Preparation of synthetic quartz glass substrates

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US7632609B2 (en) 2005-10-24 2009-12-15 Shin-Etsu Chemical Co., Ltd. Fabrication method of photomask-blank
JP6332041B2 (en) * 2014-01-20 2018-05-30 信越化学工業株式会社 Method for producing synthetic quartz glass substrate

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2338849A1 (en) 2009-12-28 2011-06-29 Shin-Etsu Chemical Co., Ltd. Preparation of synthetic quartz glass substrates
CN102179731A (en) * 2009-12-28 2011-09-14 信越化学工业株式会社 Preparation of synthetic quartz glass substrates
US8500517B2 (en) 2009-12-28 2013-08-06 Shin-Etsu Chemical Co., Ltd. Preparation of synthetic quartz glass substrates
CN102179731B (en) * 2009-12-28 2014-11-05 信越化学工业株式会社 Preparation of synthetic quartz glass substrates

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