JP2010175660A - Method for manufacturing substrate for mask blank and method for manufacturing mask blank - Google Patents
Method for manufacturing substrate for mask blank and method for manufacturing mask blank Download PDFInfo
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- Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
- Preparing Plates And Mask In Photomechanical Process (AREA)
Abstract
Description
本発明は、マスクブランク用基板の製造方法、および基板上に１層乃至複数層のパターン形成用薄膜が形成されたマスクブランクの製造方法に関するものである。 The present invention relates to a method for manufacturing a mask blank substrate, and a method for manufacturing a mask blank in which a single layer or a plurality of layers of pattern forming thin films are formed on a substrate.
半導体ＬＳＩなどの製造に用いられる露光マスクは、基板上に１層乃至複数層のパターン形成用薄膜が形成されたマスクブランクに対して電子線などで描画を行なうことにより製造される。従って、マスクブランクの段階で基板の主表面、あるいはパターン形成用薄膜の表面に凹部や凸部からなる欠陥が存在すると、露光精度の高い露光マスクを得ることができない。そこで、マスクブランクを製造するにあたっては、マスクブランク用基板の主表面、あるいはパターン形成用薄膜の表面に欠陥が存在するか否かの検査が行なわれる。 An exposure mask used for manufacturing a semiconductor LSI or the like is manufactured by performing drawing with an electron beam or the like on a mask blank in which a single-layer or multiple-layer pattern forming thin film is formed on a substrate. Therefore, if there are defects such as recesses or protrusions on the main surface of the substrate or the surface of the pattern forming thin film at the mask blank stage, an exposure mask with high exposure accuracy cannot be obtained. Therefore, when manufacturing a mask blank, it is inspected whether or not there is a defect on the main surface of the mask blank substrate or the surface of the pattern forming thin film.
かかる検査に用いられる装置としては、各種のものが提案されているが、位相シフト法を利用したものでは、光ビーム（検査光）を干渉光学系により互いに干渉性を有する２本のサブビームに変換し、検査対象品（マスクブランク用基板、マスクブランク等）の表面に向けて照射する。検査対象品の表面に欠陥が存在する場合、２本のサブビーム間には欠陥の高さに相当する位相差が導入される。従って、検査対象品の表面からの反射光を合成すれば、合成したビームには欠陥の高さに相当する位相差が含まれるので、合成した光を光電変換装置により電気信号に変換した後、この電気信号に信号処理を行なえば、基準値以上のサイズの欠陥があるか否かを検査することができる（特許文献１参照）。 Various devices have been proposed for use in such inspection, but in the case of using the phase shift method, a light beam (inspection light) is converted into two sub-beams having mutual coherence by an interference optical system. Then, it irradiates the surface of a product to be inspected (mask blank substrate, mask blank, etc.). When a defect exists on the surface of the inspection target product, a phase difference corresponding to the height of the defect is introduced between the two sub beams. Therefore, if the reflected light from the surface of the product to be inspected is synthesized, the synthesized beam contains a phase difference corresponding to the height of the defect, so after the synthesized light is converted into an electrical signal by the photoelectric conversion device, If this electric signal is subjected to signal processing, it is possible to inspect whether or not there is a defect having a size larger than a reference value (see Patent Document 1).
しかしながら、欠陥検査装置の場合、図３（ａ）に矢印で示すように、検査対象品の表面の第１方向に走査するステップを第１方向に直交する第２方向に向かって繰り返し行い、第１方向の１回分の走査により得られる電気信号に基づいて、基準値以上のサイズの欠陥の有無を検査するため、検査の精度が低いという問題点がある。すなわち、欠陥検査装置の場合、図３（ｂ）に示すような点状の大きな欠陥１１０であれば確実に検出できるが、図３（ｃ）に示すように、第２方向に向かって延在し、第１方向のサイズが小さい欠陥１１０の場合、良品判定になる場合が多い。また、図３（ｄ）に示すような点状の欠陥１２０が第２方向に向かって点在し、欠陥一つ当たりのサイズが小さい微小欠陥である場合、良品判定になってしまう。このような微小欠陥が隣接して点在している場合、実際には連続した１つの欠陥であっても、検査精度が低いことに起因して微小欠陥が点在しているように検出されている可能性が高く、本来、良品判定とすべきではない。特に、図３（ｅ）に示すように、点状の欠陥１２０が斜め方向（特に、第１方向と第２方向の中間の傾斜角である４５度の方向）に向かって点在して延びている場合は、特に連続した１つの欠陥である可能性が高く、良品判定とすべきではない。 However, in the case of the defect inspection apparatus, as shown by an arrow in FIG. 3A, the step of scanning in the first direction on the surface of the inspection target product is repeatedly performed in the second direction orthogonal to the first direction. Since the presence or absence of a defect having a size larger than the reference value is inspected based on an electrical signal obtained by one scan in one direction, there is a problem that the inspection accuracy is low. That is, in the case of a defect inspection apparatus, a large dot-shaped defect 110 as shown in FIG. 3B can be reliably detected, but extends in the second direction as shown in FIG. However, in the case of the defect 110 having a small size in the first direction, it is often determined that the product is non-defective. In addition, when the point-like defects 120 as shown in FIG. 3D are scattered in the second direction and are small defects having a small size per defect, it is judged as a non-defective product. When such minute defects are scattered adjacently, even a single continuous defect is actually detected as being scattered due to low inspection accuracy. It is highly possible that the product is not good. In particular, as shown in FIG. 3 (e), the point-like defects 120 extend in a dotted manner toward an oblique direction (in particular, a direction of 45 degrees that is an intermediate inclination angle between the first direction and the second direction). In particular, it is highly possible that the defect is one continuous defect and should not be judged as a good product.
一方、位相差を有する２つのサブビームを用いる位相シフト法による検査方法であることから、２つのサブビームが並列する方向（第１方向）には一度に検査光を照射することはできない。また、装置の構造上、コスト上等の理由から、第２方向に一度に検査光を照射するような欠陥検査装置を作ることは難しい。単一の照射装置で、第１方向を走査するステップと、検査光を第２方向に移動するステップを繰り返して、検査対象物の表面全体に検査光を照射した場合、ステップ毎の第２方向への移動を検査光が照射されない部分が生じないような移動量に設定しても、第１方向に比べて、第２方向の検査光の照射量に不均一が生じやすく、第２方向の検査感度が不均一になりやすいという問題があった。さらに、第２方向の検査光の照射量の不均一性を解消するために、第２方向に並列に検査光の照射装置を複数配置した場合であっても、照射装置間で検査光の照射量の不均一が生じる場合があり、問題となっていた。さらに、この場合であっても、構造上やコスト上の理由から、検査対象物の第２方向全体を一度に検査光が照射するように多数の照射装置を配置することは困難であることから、検査光の第２方向への移動ステップが発生してしまい、単一の照射装置の場合と同様の問題が生じる恐れがあった。 On the other hand, since the inspection method is based on the phase shift method using two sub-beams having a phase difference, the inspection light cannot be irradiated at once in the direction in which the two sub-beams are parallel (first direction). Moreover, it is difficult to make a defect inspection apparatus that irradiates inspection light at once in the second direction because of the structure of the apparatus and cost. When a single irradiation device repeats the step of scanning in the first direction and the step of moving the inspection light in the second direction to irradiate the entire surface of the inspection object with the inspection light, the second direction for each step Even if the movement amount is set to a movement amount that does not cause a portion that is not irradiated with the inspection light, the irradiation amount of the inspection light in the second direction is likely to be non-uniform compared to the first direction. There has been a problem that the inspection sensitivity tends to be uneven. Furthermore, in order to eliminate the non-uniformity of the irradiation amount of the inspection light in the second direction, even when a plurality of inspection light irradiation devices are arranged in parallel in the second direction, the irradiation of the inspection light between the irradiation devices There was a case where the amount was uneven, which was a problem. Furthermore, even in this case, for structural and cost reasons, it is difficult to arrange a large number of irradiation devices so that the inspection light irradiates the entire second direction of the inspection object at once. As a result, a step of moving the inspection light in the second direction occurs, which may cause the same problem as in the case of a single irradiation apparatus.
これらの理由から照射装置の検査光の光量にばらつきが生じた場合、反射光量にばらつきが生じ、光電変換装置で変換される電気信号強度にもばらつきが生じてしまい、これらの結果、欠陥検出感度が変わってしまうという問題があった。 For these reasons, if the amount of inspection light from the irradiation device varies, the amount of reflected light also varies, resulting in variations in the electric signal intensity converted by the photoelectric conversion device. As a result, defect detection sensitivity There was a problem that changed.
これらの問題の解決手段として、単純に欠陥検出感度を上げる方法、すなわち、良品判定の基準の欠陥サイズの閾値を小さくする方法が考えられるが、今度は、本来、マスクブランク用ガラス基板、マスクブランクとして使用するのには実用上問題ない程度の微小欠陥であっても不良品として判定されてしまい、歩留りが大幅に悪化してしまうという大きな問題が生じてしまう。さらに、欠陥検査装置での検査で良品と判定されたものを作業者が目視で再検査する方法が考えられるが、かかる目視検査を行なうには相当の熟練を必要とするとともに、かかる熟練を有するものであっても誤判定を避けることができないという問題点がある。 As a means for solving these problems, a method of simply increasing the defect detection sensitivity, that is, a method of reducing the defect size threshold of the standard for determining the non-defective product is conceivable. Even if it is a minute defect that is practically no problem to be used as a defective product, it is determined as a defective product, resulting in a great problem that the yield is greatly deteriorated. Further, a method in which an operator visually reinspects what is determined to be a non-defective product by the inspection by the defect inspection apparatus is conceivable. However, such visual inspection requires considerable skill and has such skill. Even if it is a thing, there exists a problem that a misjudgment cannot be avoided.
以上の問題点に鑑みて、本発明の課題は、マスクブランクの製造過程で発生する欠陥を容易かつ確実に検出することができるマスクブランク用基板の製造方法、およびマスクブランクの製造方法を提供することにある。 In view of the above problems, an object of the present invention is to provide a mask blank substrate manufacturing method and a mask blank manufacturing method capable of easily and reliably detecting defects generated in the mask blank manufacturing process. There is.
上記課題を解決するために、本発明では、基板主表面の凹部または凸部からなる欠陥を検査する検査工程を有するマスクブランク用基板の製造方法において、前記検査工程は、前記基板主表面に検査光を照射した際の反射光を光電変換装置で受光して電気信号に変換し、該電気信号を前記基板主表面における位置情報と対応付けてデータ記憶部に記憶する信号取得工程と、前記電気信号に対する信号処理により、第１基準値以上のサイズである欠陥の有無を判定する第１判定工程と、前記電気信号に対する信号処理により、前記第１基準値よりも小さく第２基準値以上のサイズである微小欠陥の有無を判定する第２判定工程と、前記基板主表面で近接する複数の微小欠陥からなる微小欠陥集合体の有無を判定し、前記第１基準値以上のサイズである微小欠陥集合体の有無を判定する第３判定工程とを有することを特徴とする。 In order to solve the above-described problems, in the present invention, in the method for manufacturing a mask blank substrate having an inspection process for inspecting a defect consisting of a concave portion or a convex portion on the main surface of the substrate, the inspection step inspects the main surface of the substrate. The signal acquisition step of receiving the reflected light when irradiated with light with a photoelectric conversion device and converting it into an electrical signal, storing the electrical signal in a data storage unit in association with the positional information on the main surface of the substrate, and the electrical A first determination step for determining presence / absence of a defect having a size greater than or equal to a first reference value by signal processing for a signal, and a size that is smaller than the first reference value and greater than or equal to a second reference value by signal processing for the electrical signal A second determination step for determining the presence or absence of a micro defect, and the presence or absence of a micro defect assembly composed of a plurality of micro defects close to each other on the main surface of the substrate, and a size equal to or larger than the first reference value And having a third determination step of determining the presence or absence of certain very small defect clusters.
また、本発明では、基板上に形成されたパターン形成用薄膜の凹部または凸部からなる欠陥を検査する検査工程を有するマスクブランクの製造方法において、前記検査工程は、前記パターン形成用薄膜表面に検査光を照射した際の反射光を光電変換装置で受光して電気信号に変換し、該電気信号を前記パターン形成用薄膜表面における位置情報と対応付けてデータ記憶部に記憶する信号取得工程と、前記電気信号に対する信号処理により、第１基準値以上のサイズである欠陥の有無を判定する第１判定工程と、前記電気信号に対する信号処理により、前記第１基準値よりも小さく第２基準値以上のサイズである微小欠陥の有無を判定する第２判定工程と、前記パターン形成用薄膜表面で隣接する複数の微小欠陥からなる微小欠陥集合体の有無を判定し、前記第１基準値以上のサイズである微小欠陥集合体の有無を判定する第３判定工程とを有することを特徴とする。 Moreover, in this invention, in the manufacturing method of the mask blank which has the test | inspection process which test | inspects the defect consisting of the recessed part or convex part of the thin film for pattern formation formed on the board | substrate, the said test | inspection process is the said thin film for pattern formation. A signal acquisition step of receiving reflected light at the time of irradiating inspection light with a photoelectric conversion device and converting it into an electrical signal, and storing the electrical signal in a data storage unit in association with positional information on the surface of the pattern forming thin film; A first determination step of determining presence / absence of a defect having a size greater than or equal to a first reference value by signal processing on the electrical signal; and a second reference value smaller than the first reference value by signal processing on the electrical signal A second determination step for determining the presence or absence of microdefects having the size described above, and the presence or absence of a microdefect assembly comprising a plurality of microdefects adjacent on the surface of the pattern forming thin film Determined, characterized in that a third determination step of determining the presence or absence of micro-defect clusters is the size of more than the first reference value.
本発明では、検査対象品（基板主表面、パターン形成用薄膜）の凹部または凸部からなる欠陥を検査する検査工程を有するマスクブランク用基板あるいはマスクブランクの製造方法において、その検査工程は、まず、検査対象品に検査光を照射した際の反射光を光電変換装置で受光して電気信号に変換し、該電気信号を検査対象品表面における位置情報と対応付けてデータ記憶部に記憶する信号取得工程を行う。次に、検査対象品を良否判定するための欠陥サイズの基準値を第１基準値とし、その第１基準値以上のサイズである欠陥の有無を判定し、検査対象品の良品判定を行う。さらに、良品と判定された検査対象品に対して、第１基準値よりも小さい第２基準値（例えば、欠陥検査装置の欠陥検出限界値等）以上の微小欠陥の有無を判定し、検出された微小欠陥同士の距離関係や位置関係から近接する微小欠陥集合体の有無を判定する。最後に、微小欠陥集合体として判定されたものが第１基準値以上であるかを基準に検査対象品の良品判定を行う。 In the present invention, in the mask blank substrate or mask blank manufacturing method having an inspection process for inspecting a defect consisting of a concave portion or a convex portion of a product to be inspected (substrate main surface, pattern forming thin film), The reflected light when the inspection object is irradiated with the inspection light is received by the photoelectric conversion device and converted into an electric signal, and the electric signal is stored in the data storage unit in association with the position information on the surface of the inspection object Perform the acquisition process. Next, the defect size reference value for determining the quality of the inspection target product is set as the first reference value, the presence or absence of a defect having a size equal to or larger than the first reference value is determined, and the non-defective product determination is performed. Further, the inspection target product determined to be non-defective is determined by detecting the presence or absence of a microdefect greater than or equal to a second reference value (for example, a defect detection limit value of the defect inspection apparatus) that is smaller than the first reference value. The presence / absence of adjacent micro defect aggregates is determined from the distance relationship and positional relationship between the micro defects. Finally, non-defective product determination is performed based on whether or not the micro defect assembly is determined to be equal to or higher than the first reference value.
このような検査工程を行うことで、欠陥検査感度を上げることなく、目視検査に頼ることなく、検査光の照射量の不均一性に起因する欠陥検出感度のばらつきの影響を受けることなく、第１基準値以上の欠陥を有する不良品を確実に排除することができる。 By performing such an inspection process, without increasing the defect inspection sensitivity, without relying on visual inspection, without being affected by variations in defect detection sensitivity due to nonuniformity in the amount of inspection light irradiation, It is possible to reliably eliminate defective products having defects of one reference value or more.
本発明では、前記第３判定工程において、信号取得工程でデータ記憶部に記憶した情報を基に、微小欠陥を含む所定範囲の検査対象品（基板主表面、パターン形成用薄膜）の拡大画像を作成し、その拡大画像から微小欠陥集合体の有無を判定することが好ましい。このように構成すると、作業員が目視では発見が困難であった微小欠陥集合体の有無を容易判定することができ、検査の熟練者でなくとも確実に判定が可能であり、検査の熟練者であればより確実に判定ができるようになる。また、コンピュータを用いた画像処理によって第１基準値以上のサイズの微小欠陥集合体の有無を自動的に検出することも可能となる。 In the present invention, in the third determination step, based on the information stored in the data storage unit in the signal acquisition step, an enlarged image of the inspection target product (substrate main surface, pattern forming thin film) in a predetermined range including minute defects. It is preferable to create and determine the presence or absence of a micro defect aggregate from the enlarged image. With this configuration, an operator can easily determine the presence or absence of a micro defect assembly that was difficult to find visually, and it can be reliably determined without being an expert in inspection. Then, the determination can be made more reliably. It is also possible to automatically detect the presence or absence of a micro defect aggregate having a size equal to or larger than the first reference value by image processing using a computer.
本発明において、前記信号取得工程では、前記検査対象品の表面で隣接する２個所に２種類の偏光光を前記検査光として照射し、当該２種類の偏光光の前記検査対象品からの反射光を微分干渉観察用の複屈折プリズムにより合成した光を前記光電変換装置により電気信号に変換することが好ましい。 In the present invention, in the signal acquisition step, two types of polarized light are irradiated as the inspection light to two adjacent positions on the surface of the inspection target product, and the reflected light from the inspection target product of the two types of polarized light is irradiated. It is preferable that the light synthesized by the birefringent prism for differential interference observation is converted into an electric signal by the photoelectric conversion device.
本発明において、前記第１判定工程では、例えば、前記検査対象品の表面の第１方向へ走査するステップを当該第１方向に直交する第２方向に向かって繰り返し行い、前記第１方向の１回分の走査により得られる電気信号に基づいて、前記第１基準値以上のサイズの欠陥の有無を検査する。このような構成の場合に対して、本発明は非常に有効に作用し、第２方向全体に検査光の照射・受光装置を並列に配置した大掛かりな欠陥検査装置を用いずとも、確実に第１基準値以上の欠陥を判定することができる。 In the present invention, in the first determination step, for example, the step of scanning in the first direction of the surface of the inspection object is repeatedly performed in a second direction orthogonal to the first direction, and 1 in the first direction is performed. The presence or absence of a defect having a size equal to or larger than the first reference value is inspected based on an electrical signal obtained by scanning for one time. In the case of such a configuration, the present invention works very effectively, and without fail, without using a large defect inspection apparatus in which inspection light irradiation / light receiving devices are arranged in parallel in the entire second direction. Defects greater than one reference value can be determined.
本発明において、前記検査対象品は、例えば、前記基板上に前記パターン形成用薄膜が形成されてなる。 In the present invention, the inspection object product is formed, for example, by forming the pattern forming thin film on the substrate.
本発明は、前記検査対象品が、前記基板上に前記パターン形成用薄膜としてハーフトーン位相シフト膜が形成されてなる場合に適用すると特に効果的である。特にハーフトーン位相シフトマスクの場合は、露光光の波長の位相を所定量シフトさせる機能と、露光光を所定透過率で透過させる機能が膜面全体で均一である必要があるため、欠陥への良否判定基準が特に厳しい。特に露光光の波長が短波長化されるに伴って、欠陥に対して許容されるサイズが厳しくなっている。本発明に係る検査方法によれば、かかる厳しい要求にも十分対応できる検査を行なうことができる。また、ハーフトーン位相シフト膜は、透光性を備えているため、目視による検査が特に難しいが、本発明によって欠陥を確実に検査することができる。 The present invention is particularly effective when applied to a case where the product to be inspected is formed with a halftone phase shift film as the pattern forming thin film on the substrate. In particular, in the case of a halftone phase shift mask, the function of shifting the phase of the wavelength of the exposure light by a predetermined amount and the function of transmitting the exposure light at a predetermined transmittance must be uniform over the entire film surface. Pass / fail criteria are particularly strict. In particular, as the wavelength of exposure light is shortened, the allowable size for defects is becoming stricter. According to the inspection method of the present invention, it is possible to perform an inspection that can sufficiently cope with such strict requirements. Further, since the halftone phase shift film has translucency, it is particularly difficult to visually inspect, but the present invention can reliably inspect defects.
本発明では、検査対象品（基板主表面、パターン形成用薄膜）の凹部または凸部からなる欠陥を検査する検査工程を有するマスクブランク用基板あるいはマスクブランクの製造方法において、その検査工程は、まず、検査対象品に検査光を照射した際の反射光を光電変換装置で受光して電気信号に変換し、該電気信号を検査対象品における位置情報と対応付けてデータ記憶部に記憶する信号取得工程を行う。次に、検査対象品を良否判定するための欠陥サイズの基準値を第１基準値とし、その第１基準値以上のサイズである欠陥の有無を判定し、検査対象品の良品判定を行う。さらに、良品と判定された検査対象品に対して、第１基準値よりも小さい第２基準値（例えば、欠陥検査装置の欠陥検出限界値等）以上の微小欠陥の有無を判定し、検出された微小欠陥同士の距離関係や位置関係から近接する微小欠陥集合体の有無を判定する。最後に、微小欠陥集合体として判定されたものが第１基準値以上であるかを基準に検査対象品の良品判定を行う。このような検査工程を行うことで、欠陥検査感度を上げなくとも、第１基準値以上の欠陥を有する不良品を確実に排除することができ、欠陥検査感度を上げることによる歩留りの大幅な低下を回避することができる。また、作業員による検査対象品に対する直接の目視検査に頼る必要がない。さらに、検査光の照射量の不均一性に起因する欠陥検出感度のばらつきの影響を受けることなく、第１基準値以上の欠陥を有する不良品を確実に排除することができる。 In the present invention, in the mask blank substrate or mask blank manufacturing method having an inspection process for inspecting a defect consisting of a concave portion or a convex portion of a product to be inspected (substrate main surface, pattern forming thin film), In this case, the reflected light when the inspection object is irradiated with the inspection light is received by the photoelectric conversion device, converted into an electric signal, and the electric signal is stored in the data storage unit in association with the position information of the inspection object. Perform the process. Next, the defect size reference value for determining the quality of the inspection target product is set as the first reference value, the presence or absence of a defect having a size equal to or larger than the first reference value is determined, and the non-defective product determination is performed. Further, the inspection target product determined to be non-defective is determined by detecting the presence or absence of a microdefect greater than or equal to a second reference value (for example, a defect detection limit value of the defect inspection apparatus) that is smaller than the first reference value. The presence / absence of adjacent micro defect aggregates is determined from the distance relationship and positional relationship between the micro defects. Finally, non-defective product determination is performed based on whether or not the micro defect assembly is determined to be equal to or higher than the first reference value. By performing such an inspection process, it is possible to reliably eliminate defective products having defects of the first reference value or higher without increasing the defect inspection sensitivity, and a significant decrease in yield due to increased defect inspection sensitivity. Can be avoided. Moreover, it is not necessary to rely on direct visual inspection of the inspection target product by the worker. Furthermore, it is possible to reliably eliminate defective products having defects of the first reference value or more without being affected by variations in defect detection sensitivity due to non-uniformity of the inspection light irradiation amount.
図面を参照して、本発明の実施の形態を説明する。 Embodiments of the present invention will be described with reference to the drawings.
［全体構成］
図１は、本発明を適用したマスクブランクの製造方法を示すフローチャートである。図１において、点線で分割された上中下の三段のうち、下段は工程の流れを示し、中段は各工程に対応した製造過程のマスクブランクを示し、上段は検査工程で生成される膜情報を示す。図１に示すように、本発明を適用したマスクブランクの製造方法では、ガラス基板（マスクブランク用基板）１０に、パターン形成用薄膜として１次膜１１および２次膜１２を形成し、さらにレジスト膜１７を形成してマスクブランク１００を製造するとともに、製造したマスクブランク１００を収納ケース２０に収納して出荷する。かかる工程と並行して膜情報取得処理が行なわれ、ガラス基板１０の状態、１次膜１１、２次膜１２およびレジスト膜１７を各々形成する毎に表面の検査を行ってその結果に応じた基板情報、１次膜膜情報、２次膜膜情報、およびレジスト膜膜情報をホストコンピュータ８０に登録する。ホストコンピュータ８０は、これらの情報をまとめてマスクブランク膜情報を生成して蓄積し、外部からの要求に応じて蓄積したマスクブランク膜情報を紙・電子媒体・通信回線等に出力する。
[overall structure]
FIG. 1 is a flowchart showing a method for manufacturing a mask blank to which the present invention is applied. In FIG. 1, among the upper, middle, and lower three stages divided by dotted lines, the lower part shows the flow of the process, the middle part shows the mask blank of the manufacturing process corresponding to each process, and the upper part shows the film generated in the inspection process. Indicates information. As shown in FIG. 1, in a mask blank manufacturing method to which the present invention is applied, a primary film 11 and a secondary film 12 are formed on a glass substrate (mask blank substrate) 10 as a pattern forming thin film, and a resist is further formed. The mask blank 100 is manufactured by forming the film 17, and the manufactured mask blank 100 is stored in the storage case 20 and shipped. In parallel with this process, film information acquisition processing is performed, and the surface of the glass substrate 10 is inspected each time the primary film 11, the secondary film 12, and the resist film 17 are formed, and the result is determined. Substrate information, primary film information, secondary film information, and resist film information are registered in the host computer 80. The host computer 80 collectively generates and stores the mask blank film information, and outputs the stored mask blank film information to a paper / electronic medium / communication line or the like in response to an external request.
以下、下段の工程の流れに沿って説明する。なお、本発明は、各種のマスクブランク１００の製造に適用できるが、以下の説明では、遮光帯形成用の遮光膜を上層に有するハーフトーン型位相シフトマスク用のマスクブランク１００を製造する場合を例示する。 Hereinafter, it demonstrates along the flow of the process of a lower stage. Although the present invention can be applied to the manufacture of various mask blanks 100, in the following description, a case of manufacturing a mask blank 100 for a halftone phase shift mask having a light-shielding film for forming a light-shielding band as an upper layer will be described. Illustrate.
（１）基板加工工程および基板検査工程ＳＴ２１
まず、ノッチマーク１が形成された合成石英基板等のガラス基板１０を準備する。ノッチマーク１は形状によって基板の硝種を示している。次に、ガラス基板１０の表面を研削・研磨加工し、所望の表面粗さと平坦度に仕上げる。研磨工程で使用した研磨剤を除去するためにガラス基板１０を洗浄した後、ガラス基板１０の表面の欠陥を検査する欠陥検査装置に搬入し、ガラス基板１０の表面に欠陥があるか否かの基板検査工程ＳＴ２１を行なう。
(1) Substrate processing step and substrate inspection step ST21
First, a glass substrate 10 such as a synthetic quartz substrate on which the notch mark 1 is formed is prepared. The notch mark 1 indicates the glass type of the substrate depending on the shape. Next, the surface of the glass substrate 10 is ground and polished to finish the desired surface roughness and flatness. After cleaning the glass substrate 10 to remove the abrasive used in the polishing process, the glass substrate 10 is carried into a defect inspection apparatus for inspecting defects on the surface of the glass substrate 10 and whether or not the surface of the glass substrate 10 has defects. A substrate inspection process ST21 is performed.
基板検査工程ＳＴ２１において良品と判定されたガラス基板１０については、ＩＤタグがついた流通ケース（図示せず）に収納する。流通ケースにはノッチマーク１を基準にガラス基板１０の方向を揃えて収納されている。なお、基板検査工程ＳＴ２１で検出されたノッチマーク１を基準とした欠陥の位置情報、欠陥サイズ、欠陥の種類（凹部欠陥、凸部欠陥）については、管理番号毎にホストコンピュータ８０に保存される。ここで取得した情報を基板情報と呼ぶ。 The glass substrate 10 determined to be non-defective in the substrate inspection process ST21 is stored in a distribution case (not shown) with an ID tag. The distribution case is accommodated with the direction of the glass substrate 10 aligned with the notch mark 1 as a reference. Note that the defect position information, defect size, and defect type (recess defect, convex defect) with reference to the notch mark 1 detected in the substrate inspection step ST21 are stored in the host computer 80 for each management number. . The information acquired here is called substrate information.
（２）１次膜成膜工程
生産管理を行うホストコンピュータ８０を使用し、流通ケースに添付したＩＤタグに、各基板を管理する管理番号を付与する。ホストコンピュータ８０は、製造工程の順序、製造条件の設定、各製造工程の情報を収集して記録・保存する。流通ケース内に収納されたガラス基板１０を枚葉式スパッタリング装置に搬入して、ノッチマーク１が形成されている側と反対側に、１次膜１１であるＭｏＳｉＮ（モリブデンシリサイド窒化物）ハーフトーン膜を反応性スパッタリングにより成膜する。この時、基板保持具によりＭｏＳｉＮ膜が形成されない箇所に膜マーク３が形成される。そして、１次膜１１付きのガラス基板１０を別の流通ケースに収納する。これと共に、１次膜成膜終了の情報がホストコンピュータ８０に保存される。流通ケースの添付のＩＤタグに管理番号が転送される。流通ケースにはノッチマーク１（又は膜マーク３）を基準にガラス基板１０の方向を揃えて収納される。
(2) Primary film forming step Using a host computer 80 for production management, a management number for managing each substrate is assigned to an ID tag attached to a distribution case. The host computer 80 collects and records / stores the order of manufacturing processes, setting of manufacturing conditions, and information on each manufacturing process. The glass substrate 10 accommodated in the distribution case is carried into a single-wafer sputtering apparatus, and the MoSiN (molybdenum silicide nitride) halftone as the primary film 11 is formed on the side opposite to the side where the notch mark 1 is formed. A film is formed by reactive sputtering. At this time, the film mark 3 is formed at a location where the MoSiN film is not formed by the substrate holder. And the glass substrate 10 with the primary film | membrane 11 is accommodated in another distribution | circulation case. At the same time, information on the completion of primary film formation is stored in the host computer 80. The management number is transferred to the ID tag attached to the distribution case. The distribution case is accommodated with the direction of the glass substrate 10 aligned with the notch mark 1 (or film mark 3) as a reference.
本形態では、１次膜１１（ハーフトーン材料膜）として、単層のＭｏＳｉＮ膜を用いたが、ＭｏＳｉＮに代えて、モリブデンシリサイド酸化窒化物膜（ＭｏＳｉＯＮ）や、モリブデンシリサイド酸化窒化炭化物膜（ＭｏＳｉＯＮＣ）、モリブデンシリサイド酸化炭化膜（ＭｏＳｉＯＣ）を用いてもよい。 In this embodiment, a single-layer MoSiN film is used as the primary film 11 (halftone material film), but instead of MoSiN, a molybdenum silicide oxynitride film (MoSiON) or a molybdenum silicide oxynitride carbide film (MoSiONC) is used. ), A molybdenum silicide oxide carbide film (MoSiOC) may be used.
また、１次膜１１については二層の膜で形成する場合もある。この場合、下層は、露光光に対して主に透過率を低下させる機能を有する透過率調整層であり、上層は、露光光に対して主に位相角（位相シフト量）を調整する機能を有する位相調整層である。透過率調整層としては、アルミニウム、チタン、バナジウム、クロム、ジルコニウム、ニオブ、モリブデン、ランタン、タンタル、タングステン、シリコン、ハフニウムの単体膜、合金膜、またはそれらの窒化物などを用いることができる。位相調整層としては、酸化珪素、窒化珪素、酸窒化珪素など、珪素(シリコン)を母体とした薄膜などが用いられる。 Further, the primary film 11 may be formed of a two-layer film. In this case, the lower layer is a transmittance adjustment layer mainly having a function of reducing the transmittance with respect to the exposure light, and the upper layer has a function of mainly adjusting a phase angle (phase shift amount) with respect to the exposure light. A phase adjusting layer. As the transmittance adjusting layer, aluminum, titanium, vanadium, chromium, zirconium, niobium, molybdenum, lanthanum, tantalum, tungsten, silicon, hafnium simple films, alloy films, nitrides thereof, or the like can be used. As the phase adjustment layer, a thin film based on silicon (silicon) such as silicon oxide, silicon nitride, or silicon oxynitride is used.
（３）１次膜検査工程ＳＴ２２
１次膜検査工程ＳＴ２２では、１次膜１１付きのガラス基板１０を、１次膜１１表面の欠陥を検査するための欠陥検査装置に搬入し、欠陥検査を行って膜情報を取得する。膜情報（膜の表面情報）として、欠陥の位置情報、欠陥のサイズ（大きさをランク別で表示）、欠陥の種類（ピンホール、パーティクル、その他）が、管理番号毎にホストコンピュータ８０に保存される。ここで取得した膜情報を１次膜膜情報と呼ぶ。１次膜検査工程ＳＴ２２で良品と判定された１次膜１１付きのガラス基板１０については、別の流通ケースに収納する。これと共に、流通ケースのＩＤタグに管理番号が転送される。流通ケースに、ノッチマーク１（又は膜マーク３）を基準に基板が方向を揃えて収納される。
(3) Primary film inspection process ST22
In the primary film inspection step ST22, the glass substrate 10 with the primary film 11 is carried into a defect inspection apparatus for inspecting defects on the surface of the primary film 11, and defect inspection is performed to obtain film information. As film information (film surface information), defect position information, defect size (size is displayed by rank), and defect type (pinhole, particle, etc.) are stored in the host computer 80 for each management number. Is done. The film information acquired here is called primary film information. The glass substrate 10 with the primary film 11 determined to be a non-defective product in the primary film inspection step ST22 is stored in another distribution case. At the same time, the management number is transferred to the ID tag of the distribution case. In the distribution case, the substrates are stored with their directions aligned with respect to the notch mark 1 (or film mark 3).
（４）２次膜成膜工程
１次膜１１付きのガラス基板１０をインライン型スパッタリング装置に搬入して、１次膜１１上に２次膜１２であるＣｒ（クロム）遮光膜を反応性スパッタリングにより成膜する。この時、基板保持部によりＣｒ膜が形成されない箇所に膜マーク６が形成される。そして、２次膜１２付きのガラス基板１０を別の流通ケースに収納する。これと共に、２次膜成膜終了の情報がホストコンピュータ８０に保存される。流通ケースに添付のＩＤタグに管理番号が転送される。流通ケースには、ノッチマーク１（又は膜マーク３、６）を基準にガラス基板１０の方向を揃えて収納する。
(4) Secondary Film Forming Step The glass substrate 10 with the primary film 11 is carried into an in-line sputtering apparatus, and a Cr (chrome) light-shielding film as the secondary film 12 is reactively sputtered on the primary film 11. The film is formed by At this time, the film mark 6 is formed at a location where the Cr film is not formed by the substrate holding portion. And the glass substrate 10 with the secondary film | membrane 12 is accommodated in another distribution | circulation case. At the same time, information on the completion of secondary film formation is stored in the host computer 80. The management number is transferred to the ID tag attached to the distribution case. In the distribution case, the glass substrate 10 is stored in the same direction with respect to the notch mark 1 (or the film marks 3 and 6).
本形態では、２次膜１２としてＣｒ遮光膜を用いたが、クロムに酸素、窒素、炭素等を含むクロム化合物、その他のクロム化合物等からなる単層または多層構造の遮光膜を用いてもよい。また、特に、ＤＲＡＭ ｈｐ４５ｎｍ世代以降の微細パターン形成用のハーフトーン型マスクブランクを製造する場合には、Ｃｒ遮光膜についても薄膜化が必要であり、表面反射防止層、遮光層、裏面反射防止層の３層の界面が明確な積層構造を形成することが望ましいが、インライン型スパッタリング装置では３層の界面が連続的になりやすい。このような場合においては、Ｃｒ遮光膜の成膜に、積層構造の界面が明確に分けることができる枚葉型スパッタリング装置で３層を順番に成膜するとよい。この場合のＣｒ遮光膜としては、表面反射防止層にＣｒＯＣＮ、遮光層にＣｒＯＮ、裏面反射防止層にＣｒＯＣＮとすることが好ましい。各層の組成を調整することで光学特性を、表面反射光と表面反射防止層と遮光層との界面で反射する反射光との間での干渉効果、裏面反射光と裏面反射防止層と遮光層との界面で反射する反射光との間での干渉効果をともに発揮されやすいようにするとよい。 In this embodiment, a Cr light-shielding film is used as the secondary film 12. However, a light-shielding film having a single-layer or multi-layer structure made of a chromium compound containing oxygen, nitrogen, carbon, or the like in chromium or other chromium compounds may be used. . In particular, when manufacturing a halftone mask blank for forming a fine pattern of DRAM hp 45 nm generation or later, it is necessary to reduce the thickness of the Cr light-shielding film, and the surface antireflection layer, the light shielding layer, and the back surface antireflection layer are required. Although it is desirable to form a laminated structure in which the interface of the three layers is clear, the interface of the three layers tends to be continuous in the in-line type sputtering apparatus. In such a case, it is preferable to form three layers in order with a single-wafer sputtering apparatus in which the interface of the laminated structure can be clearly separated for the formation of the Cr light-shielding film. In this case, the Cr light-shielding film is preferably CrOCN for the front-surface antireflection layer, CrON for the light-shielding layer, and CrOCN for the back-surface antireflection layer. The optical characteristics can be adjusted by adjusting the composition of each layer, the interference effect between the surface reflected light and the reflected light reflected at the interface between the surface antireflection layer and the light shielding layer, the back surface reflected light, the back surface antireflection layer and the light shielding layer. It is preferable that the interference effect with the reflected light reflected at the interface is easily exhibited.
（５）２次膜検査工程ＳＴ２３
２次膜検査工程ＳＴ２３では、２次膜１２付きのガラス基板１０を、２次膜１２の欠陥を検査するための欠陥検査装置に搬入し、欠陥検査を行って膜情報（膜の表面情報）を取得する。膜情報は、欠陥の位置情報、欠陥のサイズ（大きさをランク別で表示）、欠陥の種類（ピンホール、パーティクル、その他）が、管理番号毎にホストコンピュータ８０に保存される。ここで取得した膜情報を２次膜膜情報と呼ぶ。そして、２次膜検査工程ＳＴ２３で良品と判定された２次膜１２付きのガラス基板１０については、別の流通ケースに収納する。これと共に、流通ケースに添付のＩＤタグに管理番号が転送される。流通ケースには、ノッチマーク１（又は膜マーク３、６）を基準にガラス基板１０が方向を揃えて収納される。
(5) Secondary film inspection process ST23
In the secondary film inspection step ST23, the glass substrate 10 with the secondary film 12 is carried into a defect inspection apparatus for inspecting defects in the secondary film 12, and defect inspection is performed to obtain film information (film surface information). To get. As the film information, defect position information, defect size (size is displayed by rank), and defect type (pinhole, particle, etc.) are stored in the host computer 80 for each management number. The film information acquired here is called secondary film information. And about the glass substrate 10 with the secondary film 12 determined by the secondary film test | inspection process ST23 as a non-defective product, it accommodates in another distribution | circulation case. At the same time, the management number is transferred to the ID tag attached to the distribution case. In the distribution case, the glass substrate 10 is accommodated in the same direction based on the notch mark 1 (or the film marks 3 and 6).
（６）レジスト成膜工程
流通ケース内に収納された２次膜１２付きのガラス基板１０を回転塗布装置に搬入して、２次膜１２上にレジストを回転塗布法により塗布し、ベーク、冷却を経てレジスト膜１７を形成する。そして、レジスト膜１７付きのガラス基板１０（マスクブランク１００）を別の流通ケースに収納する。これと共に、レジスト膜成膜終了の情報がホストコンピュータ８０に保存される。流通ケースに添付のＩＤタグに管理番号が転送される。流通ケースには、ノッチマーク１（又は膜マーク３、６）を基準にマスクブランクの方向を揃えて収納される。
(6) Resist film forming step The glass substrate 10 with the secondary film 12 housed in the distribution case is carried into a spin coater, and the resist is coated on the secondary film 12 by the spin coat method, baked and cooled. Then, a resist film 17 is formed. And the glass substrate 10 (mask blank 100) with the resist film 17 is accommodated in another distribution case. At the same time, information on completion of resist film formation is stored in the host computer 80. The management number is transferred to the ID tag attached to the distribution case. In the distribution case, the mask blank is aligned in the direction of the notch mark 1 (or the film marks 3 and 6).
（７）レジスト膜検査工程ＳＴ２４
レジスト膜検査工程ＳＴ２４では、レジスト膜１７付きのガラス基板１０（マスクブランク１００）を、欠陥検査装置に搬入し、欠陥検査を行って膜情報を取得する。膜情報として、欠陥の位置情報、欠陥のサイズ（大きさをランク別で表示）、欠陥の種類（ピンホール、パーティクル、その他）が管理番号毎にホストコンピュータ８０に保存される。ここで取得した膜情報をレジスト膜膜情報と呼ぶ。レジスト膜検査工程ＳＴ２４で良品と判定されたガラス基板１０については、別の流通ケースに収納する。これと共に、流通ケースに添付のＩＤタグに管理番号が転送される。流通ケースには、ノッチマーク１（又は膜マーク３、６）を基準にマスクブランク１００の方向を揃えて収納する。
(7) Resist film inspection process ST24
In the resist film inspection step ST24, the glass substrate 10 (mask blank 100) with the resist film 17 is carried into a defect inspection apparatus, and defect inspection is performed to obtain film information. As the film information, defect position information, defect size (size is displayed by rank), and defect type (pinhole, particle, etc.) are stored in the host computer 80 for each management number. The film information acquired here is referred to as resist film film information. The glass substrate 10 determined to be a non-defective product in the resist film inspection process ST24 is stored in another distribution case. At the same time, the management number is transferred to the ID tag attached to the distribution case. In the distribution case, the mask blank 100 is stored in the same direction based on the notch mark 1 (or the film marks 3 and 6).
（８）膜情報の照合工程
基板情報、１次膜膜情報、２次膜膜情報、レジスト膜膜情報を互いに照合することにより、膜情報同士の間で方向が一致しているか確認する。具体的には、位置変化しない欠陥を基準に各膜の欠陥情報データを照合する。これは、最下層の膜である１次膜１１に欠陥がある場合、１次膜１１より上層の膜である２次膜１２、レジスト膜１７にも欠陥が生じることを利用して、１次膜膜情報を基準として他の膜情報の方向の正否を判定する。これにより、マスクブランク１００の製造過程（１）〜（９）における基板の向きを一定に保ち、基板の向きと膜情報の向きとの不一致を避けると共に、膜情報同士間の向きを一致させることができ、基板の向きと全ての膜情報の向きとを一致させることができる。また、膜情報同士の一致を確認するので、仮に製造過程で基板の向きを間違って流通ケースや収納ケースに収めたとしても、それを検出することが可能である。なお、この実施の形態では、欠陥位置情報の基準点としてノッチマークや膜マークを用いたが、基板のパターン転写に影響を与えない部分の主表面に基準点マークをレーザー掘込、ダイヤモンド針による打刻、エッチング等より形成することにより、欠陥位置情報の精度が大幅に向上する。また、この実施の形態では、流通ケースにＩＤタグを付けることで、マスクブランク用ガラス基板の基板情報やマスクブランクの１次膜膜情報、２次膜膜情報、レジスト膜膜情報を関連付けしたが、これに代えて、基板の端面や、パターン転写に影響を与えない部分の主表面に２次元コード等の識別マークを打刻し、この識別マークと関連付けするようにしてもよい。このようにすると、より確実に関連付けができる。
(8) Film information collation step The substrate information, the primary film film information, the secondary film film information, and the resist film film information are collated with each other to confirm whether the directions of the film information match each other. Specifically, the defect information data of each film is collated based on the defect whose position does not change. This is because when there is a defect in the primary film 11 that is the lowermost layer film, defects are also generated in the secondary film 12 and the resist film 17 that are upper layers than the primary film 11. The correctness of the direction of other film information is determined based on the film film information. Thereby, the orientation of the substrate in the manufacturing processes (1) to (9) of the mask blank 100 is kept constant, the mismatch between the orientation of the substrate and the orientation of the film information is avoided, and the orientation between the film information is matched. The direction of the substrate and the direction of all the film information can be matched. In addition, since the coincidence of the film information is confirmed, even if the orientation of the substrate is wrongly stored in the distribution case or the storage case in the manufacturing process, it can be detected. In this embodiment, a notch mark or a film mark is used as a reference point for defect position information. However, a reference point mark is laser engraved on the main surface of a portion that does not affect the pattern transfer of the substrate, and a diamond needle is used. By forming by stamping, etching or the like, the accuracy of the defect position information is greatly improved. In this embodiment, by attaching an ID tag to the distribution case, the mask blank glass substrate information, the mask blank primary film information, the secondary film information, and the resist film information are associated. Alternatively, an identification mark such as a two-dimensional code may be imprinted on the end surface of the substrate or the main surface of the portion that does not affect pattern transfer, and may be associated with the identification mark. In this way, the association can be made more reliably.
（９）ブランク梱包工程
マスクブランク１００を収納ケース２０に収納して梱包し、マスクメーカーに配送する。
(9) Blank packing process The mask blank 100 is stored in the storage case 20, packed, and delivered to the mask manufacturer.
［検査方法］
図２は、本発明を適用したマスクブランクの製造方法で行なう検査工程の説明図である。図２（ａ）は、欠陥検査装置全体構成を示す説明図であり、図２（ｂ）、（ｆ）は欠陥の説明図、図２（ｃ）、（ｇ）は、欠陥を観察した際の画像の説明図、図２（ｄ）、（ｈ）は、欠陥を観察した際に得られる電気信号の説明図、図２（ｅ）、（ｉ）は、電気信号を微分した後の説明図である。図３（ａ）は、図２に示す検査工程において、観察対象品の表面を走査しながら表面全体を検査する様子を示す説明図であり、図３（ｂ）〜（ｅ）は、欠陥の各種形態を示す説明図である。図４は、本発明を適用したマスクブランクの製造方法で行なう検査工程において、第２判定工程で表示装置に欠陥を画像表示した様子を示す説明図である。
[Inspection method]
FIG. 2 is an explanatory diagram of an inspection process performed by a mask blank manufacturing method to which the present invention is applied. 2A is an explanatory diagram showing the entire configuration of the defect inspection apparatus, FIGS. 2B and 2F are explanatory diagrams of the defect, and FIGS. 2C and 2G are when the defect is observed. FIGS. 2D and 2H are explanatory diagrams of electric signals obtained when the defect is observed, and FIGS. 2E and 2I are explanatory views after differentiating the electric signals. FIG. FIG. 3A is an explanatory view showing a state in which the entire surface is inspected while scanning the surface of the object to be observed in the inspection step shown in FIG. 2, and FIGS. It is explanatory drawing which shows various forms. FIG. 4 is an explanatory diagram showing a state in which defects are image-displayed on the display device in the second determination step in the inspection step performed by the mask blank manufacturing method to which the present invention is applied.
図１を参照して説明したように、本形態では、マスクブランク１００を製造するにあたって、ガラス基板１０からなる検査対象品の表面、あるいはガラス基板１０にパターン形成用薄膜（１次膜１１、２次膜１２、レジスト膜１７）を形成した検査対象品の表面の欠陥を検査する検査工程ＳＴ２１、ＳＴ２２、ＳＴ２３、ＳＴ２４を行なう。本形態では、かかる検査工程ＳＴ２１、ＳＴ２２、ＳＴ２３、ＳＴ２４のうち、検査工程ＳＴ２２、ＳＴ２３、ＳＴ２４では、図２（ａ）を参照して以下に説明する欠陥検査装置を利用して、信号取得工程、第１判定工程、第２判定工程および第３判定工程を行う。以下、ガラス基板１０に１次膜１１を形成したものを検査対象品とする検査工程ＳＴ２２を例に説明する。 As described with reference to FIG. 1, in this embodiment, when manufacturing the mask blank 100, the surface of the inspection target product made of the glass substrate 10 or the thin film for pattern formation (primary films 11, 2 on the glass substrate 10. Inspection steps ST21, ST22, ST23, and ST24 for inspecting defects on the surface of the inspection target product on which the next film 12 and the resist film 17) are formed are performed. In this embodiment, among the inspection steps ST21, ST22, ST23, and ST24, in the inspection steps ST22, ST23, and ST24, a signal acquisition step is performed using the defect inspection apparatus described below with reference to FIG. The first determination step, the second determination step, and the third determination step are performed. Hereinafter, an inspection process ST22 in which a glass substrate 10 formed with the primary film 11 is an inspection target product will be described as an example.
（信号取得工程）
図２（ａ）に示す欠陥検査装置は、光学系５０と処理装置６０とを備えており、光学系５０は、光源５１から、検査対象である１次膜１１付きのガラス基板１０（検査対象品）の表面に向かう往路上に、偏光ビームスプリッタ５２、偏光子５３、ウォランストン・プリズムからなる複屈折プリズム５４（微分干渉観察用の複屈折プリズム）、１／４波長板５５および対物レンズ５６が配置されている。複屈折プリズム５４は、入射光の偏光方向に対して４５°で交差する光学軸を有している。１次膜１１付きのガラス基板１０の表面から光電変換装置５９に向かう復路は、対物レンズ５６から偏光ビームスプリッタ５２までを往路との共通光路としており、偏光ビームスプリッタ５２から光電変換装置５９の間にはコリメートレンズ５７、およびファイバーアレイ５８を備えている。このため、光源５１から出射された光のうち、ｐ偏光の光が偏光ビームスプリッタ５２および偏光子５３を通過した後、複屈折プリズム５４に到達し、複屈折プリズム５４からは、ｐ偏光の光とｓ偏光の光が、互いずれた２つの光路をもって出射される。かかるｐ偏光の光とｓ偏光の光は、１／４波長板５５によって逆向きの円偏光の光に変換された後、１次膜１１付きのガラス基板１０の表面に到達する。ここで、１次膜１１の表面に欠陥１１０（凹部１１１あるいは凸部１１２）があると、経路長の差異から位相差が生じる。
(Signal acquisition process)
The defect inspection apparatus shown in FIG. 2A includes an optical system 50 and a processing apparatus 60, and the optical system 50 receives a glass substrate 10 with a primary film 11 (inspection object) from a light source 51. A polarizing beam splitter 52, a polarizer 53, a birefringent prism 54 (birefringent prism for differential interference observation), a quarter-wave plate 55, and an objective lens 56 on the forward path toward the surface of the product) Has been placed. The birefringent prism 54 has an optical axis that intersects the polarization direction of incident light at 45 °. The return path from the surface of the glass substrate 10 with the primary film 11 to the photoelectric conversion device 59 has a common optical path from the objective lens 56 to the polarization beam splitter 52 as a forward path, and between the polarization beam splitter 52 and the photoelectric conversion device 59. Includes a collimating lens 57 and a fiber array 58. For this reason, of the light emitted from the light source 51, the p-polarized light passes through the polarization beam splitter 52 and the polarizer 53, and then reaches the birefringent prism 54. From the birefringent prism 54, the p-polarized light is transmitted. And s-polarized light are emitted through two optical paths. The p-polarized light and s-polarized light are converted into circularly polarized light in the reverse direction by the quarter wavelength plate 55 and then reach the surface of the glass substrate 10 with the primary film 11. Here, if there is a defect 110 (concave portion 111 or convex portion 112) on the surface of the primary film 11, a phase difference is generated due to a difference in path length.
そして、１次膜１１の表面で反射した光が再び、対物レンズ５６および１／４波長板５５を通過した後、複屈折プリズム５４で合成され、その後、偏光子５３、偏光ビームスプリッタ５２、コリメートレンズ５７、およびファイバーアレイ５８を経由して、光電変換装置５９に入射すると、光電変換装置５９では、反射光が電気信号に変換される。かかる電気信号は、処理装置６０に出力される。 The light reflected by the surface of the primary film 11 again passes through the objective lens 56 and the quarter-wave plate 55 and is then synthesized by the birefringent prism 54. Thereafter, the polarizer 53, the polarization beam splitter 52, and the collimator are combined. When the light enters the photoelectric conversion device 59 via the lens 57 and the fiber array 58, the photoelectric conversion device 59 converts the reflected light into an electrical signal. Such an electrical signal is output to the processing device 60.
処理装置６０は、装置本体、表示装置６４、およびキーボードなどの入力装置などを備えており、予め、プログラム記憶部に格納されているプログラムに基づいて動作する。処理装置６０において、装置本体には、光電変換装置５９から出力された電気信号の信号処理を行なうデータ処理部６３、光電変換装置５９から出力された電気信号を記憶しておくデータ記憶部６２、および表示装置６４での表示動作を制御する表示制御部６１などが構成されている。 The processing device 60 includes a device main body, a display device 64, an input device such as a keyboard, and the like, and operates based on a program stored in advance in a program storage unit. In the processing device 60, the device main body has a data processing unit 63 for performing signal processing of the electrical signal output from the photoelectric conversion device 59, a data storage unit 62 for storing the electrical signal output from the photoelectric conversion device 59, Further, a display control unit 61 for controlling the display operation on the display device 64 is configured.
このように構成した欠陥検査装置において、１次膜１１の表面で反射した光が複屈折プリズム５４で合成されると、干渉が起こる。その際、増加的干渉が起こった部分は明るく、逆に減殺的干渉が生じた部分は暗く落ち込む。また、検査対象品の表面全体の検査は、図３（ａ）に示すように、第１方向への走査を第１方向に直交する第２方向に向かって繰り返し行う。このため、欠陥１１０が、図２（ｂ）で示す凹部１１１である場合、光電変換装置５９に届く反射光は、欠陥１１０（凹部１１１）を、図２（ｃ）に示すように、例えば、右側が明るく左側が暗い画像で形成する。その際、光電変換装置５９において、反射光を電気信号に変換すると、電気信号Ｖsは、図２（ｄ）に示す波形となる。これに対して、欠陥１１０が、図２（ｆ）で示す凸部１１２である場合、光電変換装置５９に届く反射光は、欠陥１１０（凸部１１２）を、図２（ｇ）に示すように、例えば、右側が暗く左側が明るい画像で形成する。その際、光電変換装置５９において、反射光を電気信号に変換すると、電気信号Ｖsは、図２（ｈ）に示す波形となる。 In the defect inspection apparatus configured as described above, interference occurs when light reflected by the surface of the primary film 11 is combined by the birefringent prism 54. At that time, the part where the increased interference occurs is bright, and the part where the destructive interference occurs is darkened. Further, as shown in FIG. 3A, the entire surface of the inspection target product is repeatedly scanned in the first direction in the second direction orthogonal to the first direction. For this reason, when the defect 110 is the concave portion 111 shown in FIG. 2B, the reflected light reaching the photoelectric conversion device 59 causes the defect 110 (the concave portion 111) to be, for example, as shown in FIG. The right side is bright and the left side is dark. At this time, when the photoelectric conversion device 59 converts the reflected light into an electric signal, the electric signal Vs has a waveform shown in FIG. On the other hand, when the defect 110 is the convex part 112 shown in FIG. 2F, the reflected light reaching the photoelectric conversion device 59 causes the defect 110 (the convex part 112) to be shown in FIG. In addition, for example, an image is formed in which the right side is dark and the left side is bright. At this time, when the photoelectric conversion device 59 converts the reflected light into an electric signal, the electric signal Vs has a waveform shown in FIG.
このような構成の欠陥検査装置を用いて、検査対象品であるマスクブランクの１次膜１１の表面に対して検査光を照射し、１次膜１１で反射された反射光を光電変換装置５９で受光して電気信号Ｖｓに変換し、その電気信号Ｖｓを１次膜表面における位置情報（ここでは、これに代えて、位置情報に変換可能である検査開始からの時間情報を用いている。）とともにデータ記憶部６２に記憶する。この反射光の電気信号Ｖｓの取得および１次膜表面における位置情報とともにデータ記憶部６２に記憶する一連の工程を、図３（ａ）に示すように、第１方向に対して走査しながら行い、そのステップを第２方向に向かって、検査しない部分が生じないような所定ピッチで繰り返し行う。これにより、検査対象品の検査すべき領域全体の反射光の電気信号Ｖｓをその１次膜表面における位置情報とともにデータ記憶部６２に記憶することができる。 Using the defect inspection apparatus having such a configuration, the inspection light is irradiated onto the surface of the primary film 11 of the mask blank, which is the inspection target product, and the reflected light reflected by the primary film 11 is converted into the photoelectric conversion device 59. Is received and converted into an electric signal Vs, and the electric signal Vs is converted into position information on the surface of the primary film (in this case, time information from the start of inspection that can be converted into position information is used instead). ) And the data storage unit 62. A series of steps of acquiring the electric signal Vs of the reflected light and storing it in the data storage unit 62 together with the positional information on the surface of the primary film is performed while scanning in the first direction as shown in FIG. The step is repeated in the second direction at a predetermined pitch so that a portion not to be inspected does not occur. Thereby, the electric signal Vs of the reflected light of the entire region to be inspected of the inspection target product can be stored in the data storage unit 62 together with the position information on the surface of the primary film.
（第１判定工程）
第１判定工程では、データ記憶部６２に記憶した反射光の電気信号Ｖｓのデータを基に、データ処理部６３において信号処理を行い、第１基準値以上のサイズの欠陥の有無について判定を行う。
(First determination step)
In the first determination step, signal processing is performed in the data processing unit 63 based on the data of the reflected light electric signal Vs stored in the data storage unit 62, and the presence / absence of a defect having a size equal to or larger than the first reference value is determined. .
データ処理部６３が第１判定工程を行なう際の処理は以下の通りである。まず、データ処理部６３は、図２（ｄ）、（ｈ）に示す波形の電気信号Ｖsに微分処理を行い、図２（ｅ）、（ｉ）に示す波形の信号Ｖtを得た後、この波形に含まれる３つパルスの２つのパルスＶpの間隔Ｓを計測する。かかるパルスＶpの間隔は、欠陥１１０（凹部１１１および凸部１１２）の第１方向のサイズに相当する。次に、データ処理部６３は、今回検査した検査対象品に、サイズが第１基準値、例えば、サイズが０．５μｍよりも大きい欠陥１１０があるか否かを判定する。ここで、データ処理部６３は、上記の欠陥１１０があると判定した場合、今回検査した検査対象品を不具合品と判定し、後工程への搬送を禁止する。また、データ処理部６３が検査すべき領域に第１基準値以上の欠陥１１０がないと判定した場合、第２判定工程が行われる。 Processing when the data processing unit 63 performs the first determination step is as follows. First, the data processing unit 63 performs a differentiation process on the electric signal Vs having the waveform shown in FIGS. 2D and 2H to obtain the signal Vt having the waveform shown in FIGS. An interval S between two pulses Vp of three pulses included in this waveform is measured. The interval between the pulses Vp corresponds to the size of the defect 110 (the concave portion 111 and the convex portion 112) in the first direction. Next, the data processing unit 63 determines whether or not the product to be inspected this time has a defect 110 having a size larger than a first reference value, for example, a size larger than 0.5 μm. If the data processing unit 63 determines that the defect 110 is present, the data processing unit 63 determines that the product to be inspected this time is a defective product, and prohibits conveyance to a subsequent process. On the other hand, when the data processing unit 63 determines that there is no defect 110 having the first reference value or more in the region to be inspected, the second determination step is performed.
（第２判定工程）
第２判定工程では、第１判定工程で行われた電気信号Ｖｓに対する信号処理の結果をもとに、データ処理部６３が検査対象品の検査すべき領域に対し、第１方向におけるサイズが第２基準値以上の微小欠陥１２０の有無を判定する。ここでの第２基準値は、欠陥検査装置の欠陥検出限界値としている。これは、欠陥検出限界値未満の場合、ノイズ等の電気信号エラーである場合は非常に高いことや、欠陥検出限界値未満の微小欠陥１２０が実際にあったとしても、良品と判定しても製品上問題がないためである。
(Second determination step)
In the second determination step, the size in the first direction is the size in the first direction with respect to the region to be inspected of the product to be inspected by the data processing unit 63 based on the result of the signal processing on the electric signal Vs performed in the first determination step. The presence / absence of the minute defect 120 equal to or greater than 2 reference values is determined. The second reference value here is a defect detection limit value of the defect inspection apparatus. This is because if it is less than the defect detection limit value, it is very high in the case of an electric signal error such as noise, or even if there is actually a minute defect 120 less than the defect detection limit value, This is because there are no product problems.
この第２判定工程において、データ処理部６３が検査すべき領域に、第２基準値以上のサイズの微小欠陥１２０がない検査対象品は良品として後工程に搬送される。また、データ処理部６３が、第２基準値以上のサイズの微小欠陥１２０を検出した場合、その全ての微小欠陥１２０のサイズおよび位置を、電気信号Ｖｓとともに、データ記憶部６２に記憶した後、次の第３判定工程を実施する。 In the second determination step, an inspection target product having no micro defect 120 having a size equal to or larger than the second reference value in an area to be inspected by the data processing unit 63 is transferred to a subsequent process as a non-defective product. Further, when the data processing unit 63 detects the microdefects 120 having a size equal to or larger than the second reference value, the size and position of all the microdefects 120 are stored in the data storage unit 62 together with the electric signal Vs. The next third determination step is performed.
（第３判定工程）
第３判定工程では、第２判定工程で検出された微小欠陥１２０が、近接する他の微小欠陥１２０とともに微小欠陥集合体１３０を形成していないかを判定し、微小欠陥集合体がある場合は、そのサイズが第１基準値よりも大きいものがあるかを判定する。
(Third determination step)
In the third determination step, it is determined whether the micro defect 120 detected in the second determination step forms the micro defect assembly 130 together with other micro defects 120 that are close to each other. Then, it is determined whether there is one whose size is larger than the first reference value.
最初に、図３（ｃ）に示すような第２方向に連続する第１基準値（０．５μｍ）よりも大きいサイズの欠陥１１０の有無を判定する。データ処理部では、ある微小欠陥１２０について、その位置から第２方向で直近する位置について微小欠陥１２０の有無を判定し、その位置に微小欠陥１２０が検出されている場合には、その微小欠陥１２０から第２方向に直近する位置で微小欠陥１２０の有無を判定する。このような判定を繰り返すことで、これらの微小欠陥１２０が第２方向に分割されて微小欠陥として判定されていた第２方向に連続する欠陥１１０（微小欠陥集合体でもある）であることを判定できる。そして、この欠陥１１０のサイズが第１基準値よりも大きい場合においては、今回検査した検査対象品を不具合品と判定し、後工程への搬送を禁止する。 First, the presence / absence of the defect 110 having a size larger than the first reference value (0.5 μm) continuous in the second direction as shown in FIG. In the data processing unit, the presence or absence of the micro defect 120 is determined at a position closest to the micro defect 120 in the second direction from the position, and when the micro defect 120 is detected at the position, the micro defect 120 is detected. The presence / absence of the minute defect 120 is determined at a position closest to the second direction. By repeating such determination, it is determined that these micro defects 120 are defects 110 (also a micro defect aggregate) that are divided in the second direction and are determined as micro defects in the second direction. it can. When the size of the defect 110 is larger than the first reference value, the product to be inspected this time is determined as a defective product, and conveyance to a subsequent process is prohibited.
次に、図３（ｄ）および（ｅ）に示すような、不連続であるが第１基準値（０．５μｍ）よりも大きいサイズの微小欠陥集合体１３０の有無を判定する。ここでは、検査対象品の表面の画像を、データ記憶部６２に記憶されている電気信号Ｖsに基づいて表示し、この画像に基づいて、第１基準値以上の微小欠陥集合体１３０の有無を判定する。図２（ｃ）、（ｄ）を参照して説明したように、信号取得工程における信号取得時に、検出された微小欠陥１２０が凹部１２１（図２の凹部１１１に該当）か凸部１２２（図２の凸部１１２に該当）かが分るので、図４に示すように、表示装置６４の左側領域に微小欠陥１２０の分布を簡易表示するようになっている。微小欠陥１２０が凹部１２１であれば、例えば、▽のマークで示し、微小欠陥１２０が凸部１２２であれば、例えば、△のマークで示すなど、凹部１２１と凸部１２２とを異なるマークで表示する。 Next, as shown in FIGS. 3D and 3E, it is determined whether or not there is a micro defect assembly 130 that is discontinuous but has a size larger than the first reference value (0.5 μm). Here, the image of the surface of the inspection target product is displayed based on the electrical signal Vs stored in the data storage unit 62, and based on this image, the presence / absence of the minute defect assembly 130 equal to or greater than the first reference value is displayed. judge. As described with reference to FIGS. 2C and 2D, when the signal is acquired in the signal acquisition process, the detected micro defect 120 is the recess 121 (corresponding to the recess 111 in FIG. 2) or the protrusion 122 (FIG. 2). Therefore, the distribution of the minute defects 120 is simply displayed in the left region of the display device 64 as shown in FIG. If the minute defect 120 is a concave portion 121, for example, it is indicated by a mark of ▽, and if the minute defect 120 is a convex portion 122, for example, it is indicated by a mark of Δ, for example, the concave portion 121 and the convex portion 122 are indicated by different marks. To do.
ここで、第３判定工程を行う作業者が、表示装置６４を見て▽のマークを選択する（例えば、左側領域の右上の丸で囲った部分）と、その凹部１２１を含む所定範囲の詳細な微分干渉画像である拡大画像が表示装置６４の右側領域に表示される。作業者は、その拡大画像に凹部１２１に近接した別の凹部がないか、また凹部１２１がある場合には、その位置関係から、これらの複数の凹部１２１が微小欠陥集合体１３０を形成しているか（図３（ｄ）や（ｅ）のような凹部１２１の位置関係に１つの欠陥が検査精度等の問題から別々の微小欠陥１２０として検出されていないかどうか）を判定する。そして、拡大画像に表示されている複数の凹部１２１が微小欠陥集合体１３０と判定した場合であって、その微小欠陥集合体１３０のサイズが、第１基準値である０．５μｍよりも大きい場合には、今回検査した検査対象品を不具合品と判定し、後工程への搬送を禁止する。また、全ての▽のマークの拡大画像を見て、微小欠陥集合体１３０がないと判定された場合、あるいは微小欠陥集合体１３０があってもサイズが第１基準値以下であると判定された場合には、良品として、次工程（２次膜成膜工程）に搬送することを許可する。以上のデータの全てあるいは一部は、１次膜膜情報として、図１を参照して説明したホストコンピュータ８０に保存される。 Here, when the operator who performs the third determination process selects the mark of ▽ by looking at the display device 64 (for example, the portion surrounded by the upper right circle in the left region), details of a predetermined range including the concave portion 121 are displayed. An enlarged image that is a differential interference image is displayed in the right region of the display device 64. If the enlarged image does not have another concave portion adjacent to the concave portion 121, or there is the concave portion 121, the plurality of concave portions 121 form the micro defect assembly 130 from the positional relationship. (Whether one defect is not detected as a separate minute defect 120 due to problems such as inspection accuracy) in the positional relationship of the recesses 121 as shown in FIGS. 3D and 3E. Then, when it is determined that the plurality of concave portions 121 displayed in the enlarged image are the minute defect aggregates 130, and the size of the minute defect aggregates 130 is larger than the first reference value of 0.5 μm. In this case, the product to be inspected this time is determined as a defective product, and conveyance to a subsequent process is prohibited. In addition, when it is determined that there is no micro defect assembly 130 by looking at the enlarged images of all the marks of ▽, it is determined that the size is not more than the first reference value even if there is the micro defect assembly 130. In this case, it is permitted to carry the product as a non-defective product to the next step (secondary film forming step). All or part of the above data is stored as primary film information in the host computer 80 described with reference to FIG.
なお、この実施の形態の第３判定工程では、微分干渉画像の拡大画像を作業者が目視で判定したが、これに限らず、拡大画像をコンピュータで画像処理を行い、微小欠陥１２０の位置関係を認識させ、ファジー理論やニューラルネットワーク理論等を利用して、微小欠陥集合体１３０の有無を自動的に検出させ、その微小欠陥集合体１３０のサイズが第１基準値よりも大きいか否かを判定させるようにしてもよい。 In the third determination step of this embodiment, the operator visually determines the magnified image of the differential interference image. However, the present invention is not limited to this, and the magnified image is subjected to image processing by a computer, and the positional relationship between the minute defects 120 is determined. And using fuzzy theory, neural network theory, or the like, the presence or absence of the minute defect assembly 130 is automatically detected, and whether or not the size of the minute defect assembly 130 is larger than the first reference value is determined. You may make it determine.
（他の検査工程への適用）
上記説明は、１次膜１１付きのマスクブランク用のガラス基板１０を検査対象品とし、１次膜１１の表面の検査工程ＳＴ２２において、信号取得工程、第１判定工程、第２判定工程および第３判定工程を行なった例であるが、マスクブランク用のガラス基板１０の表面に対する検査工程ＳＴ２１、２次膜１２付きのマスクブランク用のガラス基板１０を検査対象品とする検査工程ＳＴ２３、レジスト膜１７付きのガラス基板１０を検査対象品とする検査工程ＳＴ２４において、信号取得工程、第１判定工程、第２判定工程および第３判定工程を行なってもよい。
(Application to other inspection processes)
In the above description, the mask blank glass substrate 10 with the primary film 11 is an inspection target product, and in the inspection process ST22 on the surface of the primary film 11, the signal acquisition process, the first determination process, the second determination process, and the first 3 is an example in which a determination process is performed, an inspection process ST21 on the surface of the glass substrate 10 for mask blank, an inspection process ST23 using the mask blank glass substrate 10 with the secondary film 12 as an inspection object, a resist film In the inspection process ST24 in which the glass substrate 10 with 17 is an inspection object, a signal acquisition process, a first determination process, a second determination process, and a third determination process may be performed.
（本形態の主な効果）
以上説明したように、本形態のマスクブランク１００の製造工程では、検査対象品に検査光を照射した際の反射光を光電変換装置５９で受光して電気信号に変換し、該電気信号を基板主表面における位置情報と対応付けてデータ記憶部に記憶する信号取得工程を行い、次に検査対象品を良否判定するための欠陥サイズの基準値である第１基準値以上のサイズである欠陥の有無を判定して検査対象品の良品判定を行う第１判定工程を行い、続いて、良品と判定された検査対象品に対して、第１基準値よりも小さい第２基準値（例えば、欠陥検査装置の欠陥検出限界値等）以上の微小欠陥の有無を判定する第２判定工程を行い、最後に、検出された微小欠陥同士の距離関係や位置関係から近接する微小欠陥集合体の有無を判定し、微小欠陥集合体として判定されたものが第１基準値以上であるかを基準に検査対象品の良品判定を行う第３判定工程を行う。このため、従来では検出が難しかった図３（ｃ）に示すような、第１方向のサイズが第１基準値以下であって、第２方向に向かって第１基準値よりも大きいサイズの欠陥１１０や、従来では検出が困難であった図３（ｄ）に示すように、第２方向に向かって、第１基準値以下の微小欠陥１２０が延在する微小欠陥集合体１３０であって、第１基準値よりも大きいサイズの微小欠陥集合体１３０や、図３（ｅ）に示すように斜め方向（第１方向と第２方向に向かって延びる方向）に第１基準値以下の微小欠陥１２０が延在する微小欠陥集合体１３０であって、第１基準値よりも大きいサイズの微小欠陥集合体１３０等をより確実に検出することができる。
(Main effects of this form)
As described above, in the manufacturing process of the mask blank 100 of this embodiment, the reflected light when the inspection object is irradiated with the inspection light is received by the photoelectric conversion device 59 and converted into an electric signal, and the electric signal is converted into the substrate. A signal acquisition process is performed in which data is stored in the data storage unit in association with position information on the main surface, and then a defect having a size equal to or larger than a first reference value that is a reference value of a defect size for determining pass / fail of the inspection target product. A first determination step of determining presence / absence and determining a non-defective product to be inspected is performed, and then a second reference value (for example, a defect) smaller than the first reference value for the inspection target product determined to be non-defective The second determination step is performed to determine the presence or absence of the above-mentioned minute defect, and finally, the presence or absence of the minute defect aggregate is determined based on the distance relationship or the positional relationship between the detected minute defects. Judgment and micro defect assembly And those determined to perform third determination step for good determination of object of inspection based on whether the first reference value or more as. For this reason, as shown in FIG. 3C, which has been difficult to detect in the past, a defect having a size in the first direction that is equal to or smaller than the first reference value and that is larger than the first reference value in the second direction. 110 or a micro defect assembly 130 in which micro defects 120 having a first reference value or less extend in the second direction, as shown in FIG. A micro defect assembly 130 having a size larger than the first reference value, or a micro defect having a size equal to or smaller than the first reference value in an oblique direction (direction extending in the first direction and the second direction) as shown in FIG. It is possible to more reliably detect the minute defect assembly 130 in which 120 is extended, and which has a size larger than the first reference value.
しかも、再検査する方法と違って、熟練を有しない作業者であっても、短時間のうちに正確な判定を行なうことができ、生産性が向上する。 Moreover, unlike the re-inspection method, even an unskilled worker can make an accurate determination in a short time, thereby improving productivity.
特に、本形態は、ガラス基板１０上にパターン形成用薄膜としてハーフトーン位相シフト膜（１次膜１１）が形成されている場合に適用したため、特に効果的である。すなわち、ハーフトーン型位相シフトマスクの場合、露光光の波長が短波長化されるに伴って、欠陥１１０に対して許容されるサイズが厳しいが、本形態に係る検査方法によれば、かかる厳しい要求にも十分対応できる検査を行なうことができる。また、ハーフトーン位相シフト膜は、透光性を備えているため、目視による検査が特に難しいが、本形態では、凹凸を微分干渉観察による画像として表示するため、欠陥を確実に検査することができる。 In particular, this embodiment is particularly effective because it is applied when a halftone phase shift film (primary film 11) is formed on the glass substrate 10 as a thin film for pattern formation. That is, in the case of the halftone phase shift mask, the allowable size for the defect 110 is severe as the wavelength of the exposure light is shortened, but according to the inspection method according to the present embodiment, such a severe is required. It is possible to perform inspections that can sufficiently meet the requirements. Further, since the halftone phase shift film has translucency, inspection by visual inspection is particularly difficult. However, in this embodiment, since the unevenness is displayed as an image by differential interference observation, it is possible to inspect defects reliably. it can.
また、第１判定工程で良品と判定されたものだけに対して第２判定工程を行なうため、第２判定工程以降の対象が少ないので、検査工程を効率よく行なうことができる。しかも、第３判定工程で表示する画像は、第１判定工程で記憶されたものであるため、第２判定工程で改めて撮像する必要がないので、検査工程を効率よく行なうことができる。 In addition, since the second determination process is performed only for those determined as non-defective products in the first determination process, the number of objects after the second determination process is small, so that the inspection process can be performed efficiently. In addition, since the image displayed in the third determination step is stored in the first determination step, it is not necessary to take another image in the second determination step, so that the inspection step can be performed efficiently.
（その他の実施の形態）
上記形態では、ハーフトーン型位相シフトマスク用のマスクブランクの製造に本発明を適用した例を示したが、クロムを主成分とする３層構造の薄膜をパターン形成用薄膜として形成したバイナリーマスク用のマスクブランクや、シリコンとモリブデンとの多層反射膜上にバッファ層や吸収体層を形成した反射型ＥＵＶマスク用のマスクブランクの製造に本発明を適用してもよい。
(Other embodiments)
In the above embodiment, an example in which the present invention is applied to the manufacture of a mask blank for a halftone phase shift mask has been shown. For a binary mask in which a thin film having a three-layer structure mainly composed of chromium is formed as a thin film for pattern formation. The present invention may be applied to the manufacture of a mask blank for a reflective EUV mask in which a buffer layer or an absorber layer is formed on a multilayer reflective film of silicon and molybdenum.
１０・・マスクブランク用のガラス基板
１１・・１次膜
１２・・２次膜
１７・・レジスト膜
５０・・欠陥検査装置の光学系
６０・・欠陥検査装置の処理装置
１００・・マスクブランク
１１０・・欠陥
１２０・・微小欠陥
１３０・・・微小欠陥集合体
ＳＴ２１、ＳＴ２２、ＳＴ２３、ＳＴ２４・・検査工程
10. Glass substrate 11 for mask blank. Primary film 12 Secondary film 17 Resist film 50 Optical system 60 of defect inspection apparatus Processing apparatus 100 of defect inspection apparatus Mask blank 110 ..Defect 120 ..Micro defect 130... Defect assembly ST21, ST22, ST23, ST24 .. Inspection process
Claims (11)
前記検査工程は、
前記基板主表面に検査光を照射した際の反射光を光電変換装置で受光して電気信号に変換し、該電気信号を前記基板主表面における位置情報と対応付けてデータ記憶部に記憶する信号取得工程と、
前記電気信号に対する信号処理により、第１基準値以上のサイズである欠陥の有無を判定する第１判定工程と、
前記電気信号に対する信号処理により、前記第１基準値よりも小さく第２基準値以上のサイズである微小欠陥の有無を判定する第２判定工程と、
前記基板主表面で近接する複数の微小欠陥からなる微小欠陥集合体の有無を判定し、前記第１基準値以上のサイズである微小欠陥集合体の有無を判定する第３判定工程と
を有することを特徴とするマスクブランク用基板の製造方法。 In the method for manufacturing a mask blank substrate, which has an inspection step of inspecting a defect consisting of a concave portion or a convex portion on the main surface of the substrate,
The inspection process includes
The reflected light when the inspection light is irradiated onto the main surface of the substrate is received by a photoelectric conversion device and converted into an electric signal, and the electric signal is stored in a data storage unit in association with position information on the main surface of the substrate Acquisition process;
A first determination step of determining presence or absence of a defect having a size equal to or larger than a first reference value by signal processing on the electrical signal;
A second determination step of determining presence or absence of a micro defect having a size smaller than the first reference value and larger than or equal to the second reference value by signal processing on the electrical signal;
A third determination step of determining the presence / absence of a micro defect assembly including a plurality of micro defects adjacent to each other on the main surface of the substrate, and determining the presence / absence of the micro defect assembly having a size equal to or larger than the first reference value. A method for manufacturing a mask blank substrate characterized by the above.
前記検査工程は、
前記パターン形成用薄膜表面に検査光を照射した際の反射光を光電変換装置で受光して電気信号に変換し、該電気信号を前記パターン形成用薄膜表面における位置情報と対応付けてデータ記憶部に記憶する信号取得工程と、
前記電気信号に対する信号処理により、前記第１基準値以上のサイズである欠陥の有無を判定する第１判定工程と、
前記電気信号に対する信号処理により、前記第１基準値よりも小さく前記第２基準値以上のサイズである微小欠陥の有無を判定する第２判定工程と、
前記パターン形成用薄膜表面で隣接する複数の微小欠陥からなる微小欠陥集合体の有無を判定し、前記第１基準値以上のサイズである微小欠陥集合体の有無を判定する第３判定工程と
を有することを特徴とするマスクブランクの製造方法。 In a mask blank manufacturing method having an inspection step of inspecting a defect formed by a concave portion or a convex portion of a pattern forming thin film formed on a substrate,
The inspection process includes
Reflected light when the pattern forming thin film surface is irradiated with inspection light is received by a photoelectric conversion device and converted into an electric signal, and the electric signal is associated with position information on the pattern forming thin film surface to store data. A signal acquisition process stored in
A first determination step of determining presence or absence of a defect having a size equal to or larger than the first reference value by signal processing on the electrical signal;
A second determination step of determining presence or absence of a micro defect having a size smaller than the first reference value and larger than the second reference value by signal processing on the electrical signal;
A third determination step of determining the presence / absence of a micro defect assembly composed of a plurality of micro defects adjacent on the surface of the pattern forming thin film and determining the presence / absence of a micro defect assembly having a size equal to or larger than the first reference value; A method for producing a mask blank, comprising:
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| JP2016142572A (en) * | 2015-01-30 | 2016-08-08 | 信越化学工業株式会社 | Defect inspection method and method for radiating inspection light |
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| JP2021039022A (en) * | 2019-09-04 | 2021-03-11 | 信越化学工業株式会社 | Defect classification method and defect classification system and screening method and manufacturing method for photo mask blank |
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| JP2021039022A (en) * | 2019-09-04 | 2021-03-11 | 信越化学工業株式会社 | Defect classification method and defect classification system and screening method and manufacturing method for photo mask blank |
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