JPH06349715A - X-ray mask inspection device - Google Patents
X-ray mask inspection deviceInfo
- Publication number
- JPH06349715A JPH06349715A JP5140981A JP14098193A JPH06349715A JP H06349715 A JPH06349715 A JP H06349715A JP 5140981 A JP5140981 A JP 5140981A JP 14098193 A JP14098193 A JP 14098193A JP H06349715 A JPH06349715 A JP H06349715A
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- Prior art keywords
- ray
- mask
- mirror
- ray mask
- rays
- Prior art date
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、Ｘ線を露光光とした縮
小投影露光で使用する反射型Ｘ線マスクのパターン欠陥
の有無を検査するＸ線マスク検査装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray mask inspection apparatus for inspecting a reflective X-ray mask used for reduction projection exposure using X-rays as exposure light for the presence of pattern defects.
【０００２】[0002]
【従来の技術】半導体デバイス等の微細加工には、マス
ク（レチクル）に形成されたパターンの縮小像をウエハ
上に塗布されたフォトレジストに転写する縮小投影露光
法が広く用いられている。この縮小投影露光法では、一
般に可視光から紫外線にかけての領域の露光光が用いら
れ、そのパターン投影用のマスクとしては、ガラスによ
る露光光の透過部分とクロムによる露光光の遮光部分と
で所望のパターンを形成するいわゆる透過型マスクが用
いられる。この種のマスクでは、パターンの欠けやはみ
出し等の欠陥が生じると、露光で得られた縮小像にもそ
の欠陥が反映される。そのため、従来はマスクを製造し
た後、欠陥の有無を検査していた。このマスクの欠陥検
査は、露光光である可視光や紫外線に対して透明な部分
と不透明な部分とを調べれば良いので、容易に実行でき
た。2. Description of the Related Art A reduction projection exposure method for transferring a reduced image of a pattern formed on a mask (reticle) to a photoresist coated on a wafer is widely used for fine processing of semiconductor devices and the like. In this reduction projection exposure method, the exposure light in the region from visible light to ultraviolet light is generally used, and as a mask for pattern projection, a desired portion is formed by the exposure light transmission part by glass and the exposure light shield part by chrome. A so-called transmissive mask that forms a pattern is used. In this type of mask, when a defect such as a pattern defect or a protrusion occurs, the defect is also reflected in the reduced image obtained by exposure. Therefore, conventionally, after manufacturing a mask, the presence or absence of defects is inspected. The defect inspection of this mask can be easily performed because it is sufficient to inspect a transparent portion and an opaque portion with respect to the exposure light such as visible light and ultraviolet rays.
【０００３】ところで、従来の紫外線を用いた縮小投影
露光装置は、既に光の回折限界の解像力まで到達してお
り、さらに高い解像力を実現するためにはより波長の短
い光を露光光に用いる必要が生じてきた。そこで、露光
光として軟Ｘ線を用いたＸ線縮小投影露光装置が提案さ
れた。例えば、従来の露光装置では露光光として超高圧
水銀灯のｉ線（波長４３６nm）、ｇ線（波長３６５n
m）、ArF エキシマレーザ（波長２４８nm）などが使用
されていたが、Ｘ線縮小投影露光では波長が５〜２０nm
の軟Ｘ線を使用するため光の回折限界による解像力は波
長が短くなった分大幅に向上する。実際、従来の紫外線
を用いた縮小投影露光では、マスクを透過した露光光の
間に位相差を与えて解像度を向上させる位相シフト法を
利用したマスクや輪帯照明法などの超解像技術を駆使し
ても ０.２μｍのラインアンドスペースを露光するのが
限界であったが、Ｘ線縮小投影露光では ０.１μｍ以下
のラインアンドスペースのパターンを容易に形成するこ
とができる。By the way, the conventional reduction projection exposure apparatus using ultraviolet rays has already reached the resolution of the diffraction limit of light, and in order to realize a higher resolution, it is necessary to use light having a shorter wavelength as the exposure light. Has occurred. Therefore, an X-ray reduction projection exposure apparatus using soft X-rays as exposure light has been proposed. For example, in the conventional exposure apparatus, as the exposure light, i-line (wavelength 436 nm) and g-line (wavelength 365n) of an ultra-high pressure mercury lamp are used.
m) and ArF excimer laser (wavelength 248 nm) were used, but the wavelength is 5 to 20 nm in X-ray reduction projection exposure.
Since the soft X-ray is used, the resolving power due to the diffraction limit of light is significantly improved by the shortened wavelength. In fact, conventional reduction projection exposure using ultraviolet rays requires super-resolution techniques such as masks and ring illumination methods that use a phase shift method that improves the resolution by giving a phase difference between the exposure light that has passed through the mask. Although the limit was to expose a line and space of 0.2 μm even with full use, a line and space pattern of 0.1 μm or less can be easily formed by X-ray reduction projection exposure.
【０００４】Ｘ線縮小投影露光装置においては、通常、
マスクで反射した光が像を形成するいわゆる反射型マス
クを使用する。Ｘ線用の反射型マスクでは、界面の振幅
反射率の高い物質の組合せを何層も積層させることで反
射面を多数（例えば、数百層）設け、それぞれの反射波
の位相が合うように光学干渉理論に基づいて各層の厚さ
を調整した多層膜を、Ｘ線の反射部として利用する。そ
して、この多層膜の上にＸ線を反射しない吸収体を形成
するか、または多層膜の一部を除去してＸ線が反射しな
いようにすることで、多層膜による反射部と吸収体また
は多層膜の除去部による非反射部とで所望のパターンが
形成されている。In the X-ray reduction projection exposure apparatus, normally,
A so-called reflective mask is used in which light reflected by the mask forms an image. In a reflection type mask for X-rays, a large number of layers (for example, several hundred layers) are provided by laminating a combination of substances having a high amplitude reflectance at the interface, so that the phases of the reflected waves match each other. A multilayer film in which the thickness of each layer is adjusted based on the theory of optical interference is used as an X-ray reflection part. Then, an absorber that does not reflect X-rays is formed on the multilayer film, or a part of the multilayer film is removed so that X-rays are not reflected, so that the reflection part and the absorber formed by the multilayer film or A desired pattern is formed by the non-reflective portion by the removed portion of the multilayer film.
【０００５】[0005]
【発明が解決しようとする課題】上述した反射型のマス
クは、露光光としてのＸ線に対する反射率の高い部分と
低い部分とのコントラストが最も高くなるように（反射
率の差が大きくなるように）形成されるので、可視光や
紫外線、あるいは電子線に対してはコントラストが低
い。そのため、可視光、紫外線や電子線によって欠陥を
検査することは困難である。また、Ｘ線縮小投影露光装
置の縮小倍率は、作製可能な反射型マスクの寸法と光学
系を構成する個々のミラーの寸法によって制限される
が、一般に １／５〜１／１０程度である。ウエハ上に
露光するパターンの最小線幅を０.０５μｍとすると、
反射型マスク上のパターンの最小線幅は０.２５〜０.５
μｍ程度となる。この値は紫外線を用いる縮小投影露光
法で使用されるマスクパターンの最小線幅に比べて小さ
く、このような微細なパターンの欠陥を検査するために
はマスクの検査装置には少なくとも０.１〜０.２μｍ以
下の分解能が要求される。しかし、従来の検査装置は、
これだけの分解能を有していなかった。In the above-mentioned reflective mask, the contrast between the portion having a high reflectance and the portion having a low reflectance with respect to the X-rays as the exposure light is the highest (the difference in reflectance is large). Since it is formed, the contrast is low with respect to visible light, ultraviolet rays, or electron beams. Therefore, it is difficult to inspect defects with visible light, ultraviolet rays, or electron beams. The reduction magnification of the X-ray reduction projection exposure apparatus is limited to about 1/5 to 1/10, although it is limited by the dimensions of the reflective mask that can be manufactured and the dimensions of the individual mirrors constituting the optical system. If the minimum line width of the pattern to be exposed on the wafer is 0.05 μm,
The minimum line width of the pattern on the reflective mask is 0.25 to 0.5
It becomes about μm. This value is smaller than the minimum line width of the mask pattern used in the reduction projection exposure method using ultraviolet rays, and in order to inspect such a fine pattern defect, the mask inspection apparatus should have at least 0.1 to A resolution of 0.2 μm or less is required. However, conventional inspection equipment
It did not have this resolution.
【０００６】本発明は、反射型Ｘ線マスクのパターンの
欠陥を容易に検査することができるＸ線マスク検査装置
を提供することを目的とする。It is an object of the present invention to provide an X-ray mask inspection apparatus capable of easily inspecting a pattern defect of a reflective X-ray mask.
【０００７】[0007]
【課題を解決するための手段】図１を参照して説明する
と、本発明では、反射型Ｘ線マスク１に対してＸ線を照
射する照射手段２と、反射型Ｘ線マスク１を照射手段２
から照射されるＸ線と交差する方向へ相対移動させる走
査手段３と、反射型Ｘ線マスク１上で反射したＸ線を結
像させるＸ線光学系４と、Ｘ線光学系４により結像され
たＸ線像を検出する検出手段５とを備えることにより、
上述した目的を達成する。With reference to FIG. 1, an irradiation means 2 for irradiating a reflection type X-ray mask 1 with X-rays and an irradiation means for irradiating the reflection type X-ray mask 1 will be described. Two
From the scanning means 3, which is moved relative to the X-rays emitted from the X-rays, the X-ray optical system 4 which forms an image of the X-rays reflected on the reflective X-ray mask 1, and the X-ray optical system 4 forms an image. By including the detecting means 5 for detecting the captured X-ray image,
The above-mentioned object is achieved.
【０００８】照射手段２は、例えば、Ｘ線の光源と、そ
こから発生したＸ線のうち所望の波長のＸ線を取り出す
分光装置と、反射型Ｘ線マスク１上の検査する領域をＸ
線で照明する照明光学系とから構成できる。Ｘ線の光源
には、シンクロトロン放射光（Synchrotron Radiatio
n）またはレーザープラズマＸ線源を用いることができ
る。分光装置から取り出すＸ線の波長は、Ｘ線縮小投影
露光を行なうときと同じ波長にするとよい。分光装置
は、回折格子、フィルター、斜入射ミラーや多層膜ミラ
ーなどの組み合わせから構成できる。このうち斜入射ミ
ラーと多層膜ミラーは分光と同時に照明光学系を構成す
ることができる。ここで、斜入射ミラーとは、非常に平
滑な面に対してすれすれの斜入射角度でＸ線を入射させ
るとある角度以下で全反射が起こることを利用してＸ線
を反射させるものである。なお、全反射を起こす角度を
全反射臨界角という。また、多層膜ミラーとは、界面の
振幅反射率の高い物質の組合わせを何層も積層させるこ
とで反射面を多数（例えば数百層）設け、それぞれの反
射波の位相が合うように光学干渉理論に基づいて各層の
厚さを調整した多層膜を反射面に用いたものであり、垂
直入射に至るまでの任意の入射角でＸ線を反射させる。
Ｘ線光学系４には、例えば斜入射ミラー、ゾーンプレ
ートまたは多層膜ミラーを用いる。検出手段５は、好ま
しくはＭＣＰ（Micro Channel Plate）やＸ線用ＣＣＤ
（Charge Coupled Device）などの２次元検出器が用い
られるが、１次元検出器を１次元方向に走査しても良い
し、位置分解能のない検出器を２次元方向に走査しても
良い。The irradiation means 2 is, for example, an X-ray light source, a spectroscopic device for extracting X-rays of a desired wavelength from the X-rays generated from the X-ray light source, and an X-ray inspecting area on the reflective X-ray mask 1.
And an illumination optical system for illuminating with a line. Synchrotron radiation is used as the X-ray light source.
n) or a laser plasma X-ray source can be used. The wavelength of X-rays extracted from the spectroscopic device may be the same as that used when performing X-ray reduction projection exposure. The spectroscopic device can be composed of a combination of a diffraction grating, a filter, an oblique incidence mirror, a multilayer film mirror, and the like. Of these, the grazing incidence mirror and the multilayer mirror can constitute an illumination optical system at the same time as the spectrum. Here, the oblique incidence mirror reflects X-rays by utilizing the fact that when X-rays are incident on a very smooth surface at a grazing oblique incidence angle, total reflection occurs at a certain angle or less. . The angle at which total reflection occurs is called the total reflection critical angle. In addition, a multilayer mirror is provided with a large number of layers (for example, several hundred layers) by laminating a combination of substances having a high amplitude reflectance at the interface, so that the phases of reflected waves are matched with each other. A multilayer film in which the thickness of each layer is adjusted based on the theory of interference is used for the reflecting surface, and X-rays are reflected at an arbitrary incident angle up to vertical incidence.
For the X-ray optical system 4, for example, an oblique incidence mirror, a zone plate or a multilayer film mirror is used. The detection means 5 is preferably an MCP (Micro Channel Plate) or an X-ray CCD
Although a two-dimensional detector such as (Charge Coupled Device) is used, the one-dimensional detector may be scanned in the one-dimensional direction, or a detector having no positional resolution may be scanned in the two-dimensional direction.
【０００９】[0009]
【作用】本発明では、照射手段２からのＸ線を反射型Ｘ
線マスク１の表面に照射する。反射型Ｘ線マスク１の表
面で反射したＸ線はＸ線光学系４により結像し、検出手
段５上において反射型Ｘ線マスク１のパターンの拡大像
を形成する。このとき、Ｘ線を使用したことによってコ
ントラストの高い像が得られる。検出手段５でパターン
の拡大像を検出し、例えば本来のマスクパターンのデー
タと比較して反射型Ｘ線マスク１上のパターン欠陥を抽
出する。このとき、一度に観察できる領域は限られるの
で、走査手段３により反射型Ｘ線マスク１をＸ線に対し
て相対移動させながら検査を行う。In the present invention, the X-ray from the irradiation means 2 is reflected by the X-ray.
The surface of the line mask 1 is irradiated. The X-rays reflected on the surface of the reflective X-ray mask 1 are imaged by the X-ray optical system 4, and an enlarged image of the pattern of the reflective X-ray mask 1 is formed on the detection means 5. At this time, an image with high contrast is obtained by using X-rays. An enlarged image of the pattern is detected by the detection means 5, and the pattern defect on the reflective X-ray mask 1 is extracted by comparing with the data of the original mask pattern, for example. At this time, since the area that can be observed at one time is limited, the inspection is performed while the reflective X-ray mask 1 is moved relative to the X-ray by the scanning means 3.
【００１０】なお、以上では本発明の理解を容易とする
ために図１を参照して説明したが、本発明の構成は、図
１に示す形状、配置等に制限されるものではない。Although the above description has been made with reference to FIG. 1 in order to facilitate understanding of the present invention, the configuration of the present invention is not limited to the shape, arrangement, etc. shown in FIG.
【００１１】[0011]
−第１実施例− 図２に本発明の第１実施例である、斜入射ミラーを用い
たＸ線マスク検査装置の概略構成を示す。本実施例では
光源に放射光２０を用い、トロイダルミラー２２でビー
ムの形状を成形するとともに短波長のＸ線を除去し、ベ
リリウム（Be）フィルター２４で紫外から可視にかけて
の長波長成分を除去して得られた軟Ｘ線により反射型Ｘ
線マスク１０を照射した。軟Ｘ線の波長は、Ｘ線縮小投
影露光を行なうときの波長と一致させた。反射型Ｘ線マ
スク１０は、マスク面と平行な面内で互いに直交する２
方向（以下、ｘｙ方向）へ移動可能なステージ３０上に
保持させた。-First Example- Fig. 2 shows a schematic configuration of an X-ray mask inspection apparatus using an oblique incidence mirror, which is a first example of the present invention. In this embodiment, synchrotron radiation 20 is used as a light source, a toroidal mirror 22 is used to shape the beam shape, short-wavelength X-rays are removed, and a beryllium (Be) filter 24 removes long-wavelength components from ultraviolet to visible. Reflective X by soft X-ray obtained
The line mask 10 was irradiated. The wavelength of the soft X-ray was matched with the wavelength when performing X-ray reduction projection exposure. The reflection type X-ray mask 10 is orthogonal to each other in a plane parallel to the mask surface.
It was held on a stage 30 movable in the directions (hereinafter, xy directions).
【００１２】反射型Ｘ線マスク１０で反射したＸ線を、
斜入射ミラーの一種であるウォルターミラー４０によっ
てＭＣＰ５０上に拡大結像させ、その像をＭＣＰ５０で
取り込んだ。ウォルターミラー４０は、回転双曲面と回
転楕円面を組み合わせた２回反射の光学系で、一本のガ
ラス管の内面に形成されている。その拡大倍率は５０倍
とした。分解能は２０×２０μｍの領域で ０.２μｍが
得られる。ＭＣＰ５０は、０.２×０.２μｍの寸法を１
画素として１画面当たり１００×１００画素からなる画
像を取り込むように構成した。The X-rays reflected by the reflective X-ray mask 10 are
An enlarged image was formed on the MCP 50 by a Walter mirror 40 which is a kind of oblique incidence mirror, and the image was captured by the MCP 50. The Walter mirror 40 is a double-reflection optical system that combines a rotating hyperboloid and a spheroid, and is formed on the inner surface of a single glass tube. The magnification was 50 times. A resolution of 0.2 μm can be obtained in a region of 20 × 20 μm. MCP50 has a size of 0.2 x 0.2 μm
An image having 100 × 100 pixels per screen is captured as a pixel.
【００１３】以上の装置において、ステージ３０に取り
付けた反射型Ｘ線マスク１０に対してＸ線を照射しつつ
ステージ３０をｘｙ方向へ移動させて反射型Ｘ線マスク
１０の全面の像をＭＣＰ５０で取り込んだ。そして、取
り込んだ画像を本来のマスクのパターンデータと対比し
た。この結果、最小線幅０.５μｍ、使用波長１０nmの
反射型Ｘ線マスクにおいて９５％の欠陥を検出すること
ができた。なお、実施例ではウォルターミラーを用いた
が、本発明はこれに制限されることはなく、他の形状の
斜入射ミラーを用いても良い。In the apparatus described above, the stage 30 is moved in the xy directions while irradiating the reflective X-ray mask 10 mounted on the stage 30 with X-rays, and the MCP 50 is used to image the entire surface of the reflective X-ray mask 10. I captured it. Then, the captured image was compared with the original pattern data of the mask. As a result, 95% of defects could be detected in the reflective X-ray mask having the minimum line width of 0.5 μm and the wavelength used of 10 nm. Although the Walter mirror is used in the embodiment, the present invention is not limited to this, and an oblique incidence mirror having another shape may be used.
【００１４】−第２実施例− 図３に本発明の第２実施例である、ゾーンプレートを用
いたＸ線マスク検査装置の概略構成を示す。本実施例で
は光源にはレーザープラズマＸ線源２１を用い、ニッケ
ル（Ni）／炭化ホウ素（B4C）の多層膜をコートした回
転楕円体ミラー２３でＸ線を集光するとともにＸ線を単
色化し、ベリリウム（Be）フィルター２４で紫外から可
視にかけての長波長成分を除去して得られた軟Ｘ線によ
り反射型Ｘ線マスク１０を照射した。反射型Ｘ線マスク
１０は第１実施例と同様ステージ３０に取り付けた。Second Embodiment FIG. 3 shows a schematic configuration of an X-ray mask inspection apparatus using a zone plate, which is a second embodiment of the present invention. In this embodiment, a laser plasma X-ray source 21 is used as a light source, and the spheroidal mirror 23 coated with a multilayer film of nickel (Ni) / boron carbide (B 4 C) collects the X-rays. The reflection type X-ray mask 10 was irradiated with soft X-rays obtained by monochromaticizing and removing long-wavelength components from ultraviolet to visible with a beryllium (Be) filter 24. The reflective X-ray mask 10 was attached to the stage 30 as in the first embodiment.
【００１５】反射型Ｘ線マスク１０で反射したＸ線をゾ
ーンプレート４１によりＸ線用ＣＣＤ５１上に拡大結像
させ、その像をＸ線用ＣＣＤ５１で取り込んだ。ゾーン
プレート４１は、シリコンナイトライド（Si3N4）の薄
い膜の上に金（Au）でゾーンプレートパターンを形成し
たもので、分解能を決める最外周の線幅は５０nmであ
る。拡大倍率は２０倍とした。分解能は５０×５０μｍ
の領域で０.０５μｍが得られる。Ｘ線用ＣＣＤ５１
は、０.０５×０.０５μｍの寸法を１画素として１画面
当たり１０００×１０００画素からなる画像を取り込む
ように構成した。The X-ray reflected by the reflective X-ray mask 10 was magnified and imaged on the X-ray CCD 51 by the zone plate 41, and the image was captured by the X-ray CCD 51. The zone plate 41 is formed by forming a zone plate pattern of gold (Au) on a thin film of silicon nitride (Si 3 N 4 ), and the outermost line width that determines the resolution is 50 nm. The magnification was 20 times. Resolution is 50 x 50 μm
0.05 μm is obtained in the region of. CCD 51 for X-ray
Has a size of 0.05 × 0.05 μm as one pixel and is configured to capture an image composed of 1000 × 1000 pixels per screen.
【００１６】以上の装置において、ステージ３０に取り
付けた反射型Ｘ線マスク１０に対してＸ線を照射しつつ
ステージ３０をｘｙ方向へ移動させて反射型Ｘ線マスク
１０の全面の像をＸ線用ＣＣＤ５１で取り込んだ。そし
て、取り込んだ画像を本来のマスクのパターンデータと
対比した。この結果、最小線幅０.２μｍ、使用波長７n
mの反射型Ｘ線マスクにおいて９９％の欠陥を検出する
ことができた。In the above apparatus, the stage 30 is moved in the xy directions while irradiating the reflective X-ray mask 10 mounted on the stage 30 with X-rays, and an image of the entire surface of the reflective X-ray mask 10 is X-rayed. It was captured by the CCD 51 for use. Then, the captured image was compared with the original pattern data of the mask. As a result, the minimum line width is 0.2 μm and the wavelength used is 7 n
It was possible to detect 99% of defects in the reflective X-ray mask of m.
【００１７】−第３実施例− 図４に本発明の第３実施例である、シュバルツシルドミ
ラーを用いたＸ線マスク検査装置の概略構成を示す。な
お、第１、第２実施例との共通部分には同一符号を付
し、説明を省略する。本実施例では、反射型Ｘ線マスク
１０上で反射したＸ線を、多層膜ミラー光学系の一種で
あるシュバルツシルドミラー４２によりＭＣＰ５０上に
拡大結像させた。シュバルツシルドミラー４２は、多層
膜が形成された一対の凹球面４２ａおよび凸球面４２ｂ
を互いの中心が一致するように配置したものである。多
層膜にはモリブデン（Mo）／シリコン（Si）多層膜を用
い、拡大倍率は２００倍とした。分解能は１００×１０
０μｍの領域で０.１μｍが得られる。ＭＣＰ５０は、
０.１×０.１μｍの寸法を１画素として１画面当たり１
０００×１０００画素からなる画像を取り込むように構
成した。Third Embodiment FIG. 4 shows a schematic configuration of an X-ray mask inspection apparatus using a Schwarzschild mirror, which is a third embodiment of the present invention. The same parts as those of the first and second embodiments are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, the X-rays reflected on the reflective X-ray mask 10 are magnified and imaged on the MCP 50 by the Schwarzschild mirror 42 which is a kind of multilayer film mirror optical system. The Schwarzschild mirror 42 includes a pair of concave spherical surface 42a and convex spherical surface 42b on which a multilayer film is formed.
Are arranged so that their centers coincide with each other. A molybdenum (Mo) / silicon (Si) multilayer film was used as the multilayer film, and the magnification was 200 times. Resolution is 100 × 10
0.1 μm is obtained in the region of 0 μm. MCP50 is
1 pixel per screen with a size of 0.1 × 0.1 μm
It is configured to capture an image composed of 000 × 1000 pixels.
【００１８】以上の装置において、最小線幅０.３μ
ｍ、使用波長１３nmの反射型Ｘ線マスク１０の欠陥検査
を行ったところ、９８％の欠陥を検出することができ
た。なお、本実施例では２枚の球面鏡からなるシュバル
ツシルドミラーを用いたが、本発明はこれに限定される
ことはなく、３枚以上の多層膜ミラーからなる光学系や
１枚の多層膜ミラーからなる光学系を用いても良いし、
球面鏡ではなく非球面鏡を用いても良い。非球面の採用
やミラー枚数の増加によって、視野の拡大や分解能の向
上が可能である。In the above apparatus, the minimum line width is 0.3μ
When a defect inspection of the reflective X-ray mask 10 having a wavelength of 13 nm and a use wavelength of 13 nm was performed, 98% of defects could be detected. Although the Schwarzschild mirror composed of two spherical mirrors is used in this embodiment, the present invention is not limited to this, and an optical system composed of three or more multilayer film mirrors or one multilayer film mirror. You may use an optical system consisting of
An aspherical mirror may be used instead of the spherical mirror. By using an aspherical surface and increasing the number of mirrors, it is possible to expand the field of view and improve the resolution.
【００１９】以上の実施例ではすべて反射型Ｘ線マスク
１０をステージ３０に取り付け、このステージ３０をｘ
ｙ方向へ移動させてＸ線の照射位置を変化させたが、ト
ロイダルミラー２２や回転楕円体ミラー２３の向きを調
整するなどしてＸ線の光路を変化させてもよい。In all of the above embodiments, the reflective X-ray mask 10 is attached to the stage 30, and the stage 30 is moved to x.
Although the X-ray irradiation position is changed by moving in the y direction, the X-ray optical path may be changed by adjusting the directions of the toroidal mirror 22 and the spheroidal mirror 23.
【００２０】以上の実施例と請求項との対応において、
第１、第３実施例の放射光２０、トロイダルミラー２２
およびベリリウムフィルタ２４、第２実施例のレーザー
プラズマＸ線源２１、回転楕円体ミラー２３およびベリ
リウムフィルタ２４が照射手段を、ステージ３０が走査
手段を、ウォルターミラー４０、ゾーンプレート４１、
シュバルツシルドミラー４２がＸ線光学系を、ＭＣＰ５
０、Ｘ線用ＣＣＤ５１が検出手段を構成する。In the correspondence between the above embodiment and the claims,
The synchrotron radiation 20 and the toroidal mirror 22 of the first and third embodiments.
And the beryllium filter 24, the laser plasma X-ray source 21 of the second embodiment, the spheroidal mirror 23 and the beryllium filter 24 serve as the irradiation means, the stage 30 serves as the scanning means, the Walter mirror 40, the zone plate 41,
The Schwarzschild mirror 42 uses an X-ray optical system for the MCP5.
0, the X-ray CCD 51 constitutes the detecting means.
【００２１】[0021]
【発明の効果】以上説明したように、本発明によれば、
縮小投影露光時の露光光と同じＸ線で反射型マスクの検
査を行うので、反射型マスク上の反射率の高い部分と低
い部分のコントラストが高くなり、有効に欠陥検出を行
うことができる。また、可視光や紫外線と比べて非常に
波長の短いＸ線を使用するので、従来は不可能であった
高い分解能での検出が可能になり、細いパターンの微細
な欠陥も検出することができる。本発明ではＸ線結像光
学系として３つの異なる光学系を用いることができる
が、これらにはそれぞれに長所と短所があるので用途に
合わせて選択することが望ましい。斜入射ミラーを用い
た場合には、分解能はそれほど高くなく、視野も狭い
が、反射率が高く、広い波長範囲のＸ線を反射するの
で、上記３つの光学系の中ではＸ線の利用効率が最も高
い。従って、検査に要する時間を短縮できる。ゾーンプ
レートを用いた場合には、視野は狭く、Ｘ線の利用効率
も低い。また、色収差があるためＸ線を単色化しておく
必要があるが、上記３つの光学系の中では最も分解能が
高い。従って、非常に微細な欠陥を検出するのに適して
いる。多層膜ミラーを用いた場合は、分解能もＸ線の利
用効率も斜入射ミラーとゾーンプレートの中間となる
が、上記３つの光学系の中では最も広い視野をとること
ができる。視野が広ければ反射マスク全面を少ない回数
で走査することができるので、検査時間を短縮すること
ができる。また、多層膜ミラー光学系は設計の自由度が
高いので、分解能と検査に要する時間とのバランスをと
ることができる。上記のように３種類のＸ線光学系はそ
れぞれ異なる特徴を有するので、１台のＸ線マスク検査
装置の中に上記の光学系のうちの複数を同時に備えて互
いに欠点を補完するようにすれば、検査装置の総合性能
をさらに向上することができる。As described above, according to the present invention,
Since the reflective mask is inspected with the same X-ray as the exposure light at the time of the reduced projection exposure, the contrast between the high reflectance portion and the low reflectance portion on the reflective mask becomes high, and the defect can be effectively detected. Further, since X-rays having a wavelength extremely shorter than that of visible light or ultraviolet rays are used, it is possible to detect with high resolution, which was impossible in the past, and it is also possible to detect fine defects with a fine pattern. . In the present invention, three different optical systems can be used as the X-ray imaging optical system, but each of them has advantages and disadvantages, so it is desirable to select them according to the application. When the oblique incidence mirror is used, the resolution is not so high and the field of view is narrow, but the reflectance is high and the X-rays in a wide wavelength range are reflected. Therefore, the utilization efficiency of the X-rays in the above three optical systems is high. Is the highest. Therefore, the time required for the inspection can be shortened. When the zone plate is used, the field of view is narrow and the utilization efficiency of X-rays is low. Further, since there is chromatic aberration, it is necessary to make the X-ray monochromatic, but the resolution is highest among the above three optical systems. Therefore, it is suitable for detecting very fine defects. When a multilayer film mirror is used, both resolution and X-ray utilization efficiency are intermediate between the grazing incidence mirror and the zone plate, but the widest field of view among the above three optical systems can be taken. If the field of view is wide, the entire surface of the reflective mask can be scanned a small number of times, so that the inspection time can be shortened. Further, since the multilayer mirror optical system has a high degree of freedom in design, it is possible to balance the resolution and the time required for the inspection. As described above, since the three types of X-ray optical systems have different characteristics, it is advisable to simultaneously provide a plurality of the above-mentioned optical systems in one X-ray mask inspection apparatus so as to complement each other. If so, the overall performance of the inspection device can be further improved.
【図１】本発明によるＸ線マスク検査装置の原理を説明
する図である。FIG. 1 is a diagram illustrating the principle of an X-ray mask inspection apparatus according to the present invention.
【図２】本発明の第１実施例であるウォルターミラーを
用いたＸ線マスク検査装置の概略図。FIG. 2 is a schematic diagram of an X-ray mask inspection apparatus using a Walter mirror according to the first embodiment of the present invention.
【図３】本発明の第２実施例であるゾーンプレートを用
いたＸ線マスク検査装置の概略図。FIG. 3 is a schematic diagram of an X-ray mask inspection apparatus using a zone plate that is a second embodiment of the present invention.
【図４】本発明の第３実施例であるシュバルツシルドミ
ラーを用いたＸ線マスク検査装置の概略図。FIG. 4 is a schematic diagram of an X-ray mask inspection apparatus using a Schwarzschild mirror, which is a third embodiment of the present invention.
１，１０ 反射型Ｘ線マスク ２ Ｘ線の照射手段 ３ 走査手段 ４ Ｘ線光学系 ５ 検出手段 ２０ 放射光 ２１ レーザープラズマＸ線源 ２２ トロイダルミラー ２３ 回転楕円体多層膜ミラー ２４ ベリリウムフィルター ３０ ステージ ４０ ウォルターミラー ４１ ゾーンプレート ４２ シュバルツシルドミラー ５０ ＭＣＰ ５１ Ｘ線ＣＣＤ 1, 10 Reflective X-ray Mask 2 X-ray Irradiation Means 3 Scanning Means 4 X-ray Optical System 5 Detecting Means 20 Emitted Light 21 Laser Plasma X-ray Source 22 Toroidal Mirror 23 Spheroidal Multilayer Mirror 24 Beryllium Filter 30 Stage 40 Walter mirror 41 Zone plate 42 Schwarzschild mirror 50 MCP 51 X-ray CCD
Claims (5)
マスク検査装置であって、 前記反射型Ｘ線マスクに対してＸ線を照射する照射手段
と、 前記反射型Ｘ線マスクを前記照射手段から照射されるＸ
線と交差する方向へ相対移動させる走査手段と、 前記反射型Ｘ線マスク上で反射したＸ線を結像させるＸ
線光学系と、 前記Ｘ線光学系により結像されたＸ線像を検出する検出
手段と、を備えることを特徴とするＸ線マスク検査装
置。1. An X-ray mask inspection apparatus for inspecting a defect of a reflective X-ray mask, comprising: an irradiation unit that irradiates the reflective X-ray mask with X-rays; X irradiated from the irradiation means
Scanning means for relatively moving in a direction intersecting the line, and X for forming an image of the X-ray reflected on the reflective X-ray mask
An X-ray mask inspection apparatus comprising: a line optical system; and a detection unit that detects an X-ray image formed by the X-ray optical system.
れることを特徴とする請求項１記載のＸ線マスク検査装
置。2. The X-ray mask inspection apparatus according to claim 1, wherein the X-ray optical system is an oblique incidence mirror.
されることを特徴とする請求項１記載のＸ線マスク検査
装置。3. The X-ray mask inspection apparatus according to claim 1, wherein the X-ray optical system is composed of a zone plate.
れることを特徴とする請求項１記載のＸ線マスク検査装
置。4. The X-ray mask inspection apparatus according to claim 1, wherein the X-ray optical system is composed of a multilayer mirror.
ラーであることを特徴とする請求項４記載のＸ線マスク
検査装置。5. The X-ray mask inspection apparatus according to claim 4, wherein the multilayer film mirror is a Schwarzschild mirror.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14098193A JP3336361B2 (en) | 1993-06-11 | 1993-06-11 | Inspection apparatus and inspection method for reflection type X-ray mask for reduction projection exposure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14098193A JP3336361B2 (en) | 1993-06-11 | 1993-06-11 | Inspection apparatus and inspection method for reflection type X-ray mask for reduction projection exposure |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06349715A true JPH06349715A (en) | 1994-12-22 |
| JP3336361B2 JP3336361B2 (en) | 2002-10-21 |
Family
ID=15281356
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14098193A Expired - Lifetime JP3336361B2 (en) | 1993-06-11 | 1993-06-11 | Inspection apparatus and inspection method for reflection type X-ray mask for reduction projection exposure |
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| Country | Link |
|---|---|
| JP (1) | JP3336361B2 (en) |
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