JPS61191946A - Optical defect inspector - Google Patents
Optical defect inspectorInfo
- Publication number
- JPS61191946A JPS61191946A JP3200185A JP3200185A JPS61191946A JP S61191946 A JPS61191946 A JP S61191946A JP 3200185 A JP3200185 A JP 3200185A JP 3200185 A JP3200185 A JP 3200185A JP S61191946 A JPS61191946 A JP S61191946A
- Authority
- JP
- Japan
- Prior art keywords
- inspected
- light
- lens
- light source
- illumination light
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8806—Specially adapted optical and illumination features
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8806—Specially adapted optical and illumination features
- G01N2021/8822—Dark field detection
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明は、光学的ディスクや機械的ディスク等の被検査
物表面の欠陥、キズ、異物の付着を光学的に検査する光
学的欠陥検査装置に関するものである。Detailed Description of the Invention Field of the Invention The present invention relates to an optical defect inspection device for optically inspecting the surface of an object to be inspected, such as an optical disk or a mechanical disk, for defects, scratches, and adhesion of foreign matter. It is.
従来の技術
近年、光ディスク（ＶＬＰ）、コンパクトディスク（Ｃ
Ｄ）、追記録可能ディスクなど種々のシステムが開発さ
れ、製品化されている。Conventional technology In recent years, optical discs (VLP), compact discs (C
D) Various systems such as recordable discs have been developed and commercialized.
このようなシステムで用いる。ディスクは、画像。Used in such systems. The disk is an image.
音声、アドレスデータ、ディジタルデータなどの情報を
凹凸の変化として、主として光学的に原盤に記録し、原
盤よシメッキ工程で金型を造シ、この金型を用いて複製
ディスクを大量に生産している。この複製ディスクの製
造工程において生ずる欠陥の発生原因として、■ガラス
原盤表面の傷、■ガラス原盤の洗浄状態（異物の吐着）
、■レジスト中の異物、■レジストのピンホール、■工
程作業中のケアレスミス、■複製材料の金型への吐着、
など種々考えられる。これらの欠陥を早期に発見し、不
良品を次工程に流すことを防ぐ為の欠陥検査装置、検査
技術は工程の歩留シ、コストダウンを考える場合、非常
に重要である。Information such as voice, address data, digital data, etc. is recorded mainly optically on the master disc as changes in unevenness, a mold is made from the master disc in a plating process, and this mold is used to mass-produce duplicate discs. There is. The causes of defects that occur during the manufacturing process of this duplicate disc include: ■ Scratches on the surface of the glass master disk; ■ Cleaning conditions of the glass master disk (discharge of foreign matter)
, ■Foreign matter in the resist, ■Pinholes in the resist, ■Careless mistakes during process work, ■Spraying of replication material onto the mold,
There are various possibilities such as. Defect inspection equipment and inspection techniques that detect these defects early and prevent defective products from being sent to the next process are extremely important when considering process yield and cost reduction.
ここでは、光学的なディスク製造工程について述べたが
、例えば機械式記録などに７よるディスク作成工程にお
いても同様の検査が必要となる。また、ディスクに限ら
ず、シリコンウェハーや、鋼板、アルミ板の表面上の欠
陥やキズなどの検査は重要なことである。Although the optical disk manufacturing process has been described here, similar inspections are also required in the disk manufacturing process using, for example, mechanical recording. Furthermore, it is important to inspect not only disks but also silicon wafers, steel plates, and aluminum plates for defects and scratches on their surfaces.
以下、主として回転する被検査物表面の欠陥検査につい
て述べる。Defect inspection on the surface of a rotating inspection object will be mainly described below.
従来の原盤表面の欠陥検査装置の一例として特公昭５２
−１４６６０１号公報に示されるような欠陥検査装置が
ある。第１１図にその原理図を示す。光源１（例えばレ
ーザー）からのコヒーレント光はミラー２の反射面を越
えたある一点に集まるようにレンズ３によって集束され
る。この鏡面に入射する集束ビームはそこで反射されて
第１の中継レンズ４，６へ投射される。このレンズ４゜
５を通過した光ビームはミラー６で反射されて第２の中
継レンズ７．８を通過してモータ９で回転しているター
ンテーブル１ｏ上の被検査物１１の表面へ進む。中継レ
ンズ７．８から出る光ビームは、被検査物１１の表面を
越えたある位置にある焦点へ集束されて、これを遮ぎる
被検査物面に光スポットを形成する。スポット径はほぼ
１００μｍ程度である。入射光ビームの方向は、その光
軸が被検査物１１の面に非平行な関係を持ち、被検査物
１１の中心軸線に対しである選ばれた角度（例えば４６
度）を作り、被検査物１１の半径に沿って被検査物１１
の表面と交わり、、かつ、被検査物１１の中心軸線を含
む平面上にあることが望まれている。入射光は被検査物
１１の表面で反射されビームスプリッタ１２に入射され
る。このビームスプリッタ１２は入射する光の一部を透
過させて第１の光検出器１３へ向って進行させ、残りを
第２の光検出器１４へ向って反射する。遮光板１５は回
折格子として働く被検査物１１の０次回折光をカットす
る為のもので、被検査物１１上に欠陥かない場合、光は
光検出器１３では検出されない。As an example of a conventional master disc surface defect inspection device,
There is a defect inspection device as shown in Japanese Patent No.-146601. FIG. 11 shows a diagram of its principle. Coherent light from a light source 1 (for example, a laser) is focused by a lens 3 so as to be concentrated at a certain point beyond the reflective surface of a mirror 2. A focused beam incident on this mirror surface is reflected there and projected onto the first relay lenses 4 and 6. The light beam that has passed through this lens 4.5 is reflected by a mirror 6, passes through a second relay lens 7.8, and proceeds to the surface of an object to be inspected 11 on a turntable 1o that is being rotated by a motor 9. The light beam emerging from the relay lens 7.8 is focused to a focal point at a certain position beyond the surface of the object to be inspected 11 and forms a light spot on the surface of the object to be inspected that blocks this. The spot diameter is approximately 100 μm. The direction of the incident light beam is such that its optical axis has a non-parallel relationship to the plane of the test object 11 and is at a selected angle (e.g. 46
degree) and move the object 11 along the radius of the object 11 to be inspected.
It is desired that the plane be on a plane that intersects the surface of the object 11 and includes the central axis of the object 11 to be inspected. The incident light is reflected by the surface of the object to be inspected 11 and enters the beam splitter 12 . The beam splitter 12 transmits a portion of the incident light to proceed toward the first photodetector 13 and reflects the remainder toward the second photodetector 14 . The light shielding plate 15 is for cutting off the 0th order diffracted light of the object 11 to be inspected, which acts as a diffraction grating, and if there is no defect on the object 11 to be inspected, the light will not be detected by the photodetector 13.
光検出器１４はディスク上での光スポットを一定に保つ
ためのもので、この検出出力により、ミラー２，６を動
かし、光ビーム位置を被検査物１１の面上で半径方向及
び接線方向へ検出器１４上でスポットが動かないように
補正する。The photodetector 14 is used to maintain a constant light spot on the disk, and the detection output moves the mirrors 2 and 6 to change the light beam position in the radial and tangential directions on the surface of the object 11 to be inspected. Correction is made so that the spot does not move on the detector 14.
発明が解決しようとする問題点
しかしながら、従来の欠陥検査装置において、次のよう
な問題点がある。Problems to be Solved by the Invention However, the conventional defect inspection apparatus has the following problems.
（１）欠陥の発生原因を追求し、不良被検査物の発生を
極力抑えることによる歩留りの向上と、コストダウンを
追求するためには、１μｍ程度の欠陥を検出でき、その
個数２位置を分類できることが望ましいが、従来装置の
場合、スポット径を１０μｍ以下にして使用することが
できず、数μｍ以下の欠陥が同時に複数個検出された場
合、それを分離することができず、欠陥の大きさ１個数
が不正確になる。(1) In order to pursue the cause of defects and to improve yield and reduce costs by minimizing the occurrence of defective inspection objects, it is necessary to detect defects of about 1 μm and classify the number and position of defects. However, conventional equipment cannot be used with a spot diameter of 10 μm or less, and if multiple defects of several μm or less are detected at the same time, they cannot be separated, and the size of the defect cannot be determined. The number of pieces becomes inaccurate.
（２）前記問題点（１）を解決するためスポット径を小
さくし、欠陥の分離能力を向上させた場合、被検査物の
一回転で走査し得る部分の幅が狭くなる。被検査物全面
を検査するためには、光学系又はターンテーブルを半径
方向に送るピッチをスポット径に一致させねばならない
ため送りピッチも小さくなり、検査に長時間を要する。(2) In order to solve the problem (1), when the spot diameter is made smaller and the defect separation ability is improved, the width of the part that can be scanned in one revolution of the object to be inspected becomes narrower. In order to inspect the entire surface of the object to be inspected, the pitch at which the optical system or turntable is sent in the radial direction must match the spot diameter, so the feeding pitch becomes small and the inspection takes a long time.
例えば４５０ｒｐｍで回転している被検査物上の３００
〜ｉｏｏｍφの部分を１０μｍのスポットで走査する場
合、送りピッチが１０μｍであるから約２２分を要する
。For example, 300 rpm on a test object rotating at 450 rpm.
When scanning a portion of ~ioomφ with a spot of 10 μm, it takes about 22 minutes since the feed pitch is 10 μm.
（３）検査時間を節約するため、送りピッチをスポット
径よシも大きくすると、飛び越し走査となって走査され
ない部分が生じ、その部分に存在する欠陥は検出できな
く、欠陥検出の精度及び再現性が悪くなる。(3) In order to save inspection time, if the feed pitch is increased as well as the spot diameter, interlaced scanning will occur and some parts will not be scanned, making it impossible to detect defects in those parts, which will improve the accuracy and reproducibility of defect detection. becomes worse.
（４）被検査物上に集束する照明光の光路と、欠陥によ
り散乱光が光検出器にに至る光路とが別々に構成されて
おり、調整が複雑である。(4) The optical path of the illumination light focused on the object to be inspected and the optical path of the light scattered by the defect leading to the photodetector are configured separately, and adjustment is complicated.
本発明はかかる点に鑑み、コントラストが良く、欠陥検
出能力の高い暗視野照明による欠陥検出を行ない、また
その照明光の径を小さくすることによる検査時間の増加
をまねくことなく分離能力を１μｍ程度になし得る光学
的欠陥検査装置を提供するものである。In view of these points, the present invention detects defects using dark field illumination, which has good contrast and high defect detection ability, and also reduces the diameter of the illumination light to increase the separation ability to about 1 μm without increasing the inspection time. The present invention provides an optical defect inspection device that can be used to inspect defects.
、ｉ。,i.
間倉ソ解決するための手段
上記問題を解決するために本発明の光学的欠陥検査装置
は、被検査物の表面を照明する光源と、前記光源からの
出射光を前記被検査物に対し斜めに照射し照明光とする
手段と、前記被検査物の表面に存在する欠陥による前記
照明光の散乱光を受けるレンズと、前記被検査物上に焦
点位置が来る様に前記レンズのフォーカス制御を行なう
手段と前記散乱光を検出するための一次元配列多素子光
検出器と、前記散乱光を前記一次元配列多素子検出器上
に結像する前記レンズを含む光学的手段よりなる光学系
と、前記被検査物を走査する手段と、前記走査の幅を前
記一次元配列多素子光検出器の素子数に対応させる手段
を有するものである。Means for Solving the Problems In order to solve the above problems, the optical defect inspection apparatus of the present invention includes a light source that illuminates the surface of the object to be inspected, and a light source that directs the emitted light from the light source obliquely to the object to be inspected. means for irradiating the object to produce illumination light; a lens for receiving scattered light of the illumination light due to defects existing on the surface of the object to be inspected; and controlling the focus of the lens so that the focal point is on the object to be inspected. an optical system comprising an optical means including a means, a one-dimensionally arrayed multi-element photodetector for detecting the scattered light, and the lens for imaging the scattered light onto the one-dimensionally arrayed multi-element detector; The apparatus includes means for scanning the object to be inspected, and means for making the scanning width correspond to the number of elements of the one-dimensional array multi-element photodetector.
作 用
本発明は前記の構成により、暗視野照明光で照明された
被検査物上の欠陥によって散乱した光を一次元配列多素
子光検出器上に集光させて欠陥を検出し、これによシ被
検査物上を一次元的に検査するため、螺旋状走査の送シ
ピッチの幅を持った帯状の領域の検査ができ、高い欠陥
検出能力と分離能力とを維持しつつ、広範囲の検査を短
時間に行なうことができる。According to the above-described configuration, the present invention detects defects by condensing light scattered by defects on an object to be inspected illuminated with dark-field illumination light onto a one-dimensionally arrayed multi-element photodetector. Since the object to be inspected is inspected one-dimensionally, it is possible to inspect a strip-shaped area with the width of the feed pitch of spiral scanning, and it is possible to inspect a wide range while maintaining high defect detection and separation capabilities. can be done in a short time.
実施例
以下、本発明の実施例を添付図面にもとづいて説明する
。Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.
第１図は本発明の第１の実施例である。第１図において
、照明用の光源１５（例えばＨｅ −Ｎ ｏレーザー）
から出た光はレンズ１６．１７によって必要な径の平行
光になった後、ドーナツ状のミラー１８により暗視野照
明に必要な部分の光だけを対物レンズ２０の方向に反射
する。この光が対物レンズ２ｏの側面に取付けられたリ
ング状の集光器２１に入射し、その集光器２１の出射光
が被検査物１１の表面の検査される部分を被検査物１１
に対して斜めに照射する暗視野照明光となる。被検査物
１１の表面に第２図の様に欠陥１１ａが在った場合、照
明光は欠陥により散乱されて、その散乱光の一部が対物
レンズ２０に戻る。対物レンズ２ｏとレンズ２２は被検
査物１１の表面を一次元配列光検出器２３の上に結像さ
せる結像系を構成しており、欠陥による散乱光からその
欠陥の大きさに対応した光スポットが一次元配列光検出
器２３の上に形成される０ここで対物レンズ２０の焦点
距離ｆ１＝＝４．２ａ＋、レンズ２２の焦点距離ｆ２＝
２５２ｊ８なるレンズを使用すれば被検査物１１上の１
μｍの欠陥が一次元配列光検出器２３上では６０μｍの
輝点として観測される。この一次元配列光検出器２３に
素子ピッチ６０μｍ、素子数３２のものを使用すれば、
光検出器２３の１素子が被検査物１１上の１μｍに対応
するため、光検出器２３の各素子から個別に欠陥信号を
取出すことにより、３２μｍの直線の領域を分離能力１
μｍで同時に検査できる。FIG. 1 shows a first embodiment of the invention. In FIG. 1, a light source 15 for illumination (e.g. He-No laser)
The light emitted from the lens 16 and 17 is turned into parallel light having a required diameter, and then a donut-shaped mirror 18 reflects only the part of the light necessary for dark-field illumination toward the objective lens 20. This light enters a ring-shaped condenser 21 attached to the side surface of the objective lens 2o, and the emitted light from the condenser 21 directs the portion of the surface of the object 11 to be inspected onto the object 11.
This is dark-field illumination light that is applied obliquely to the object. If there is a defect 11a on the surface of the inspection object 11 as shown in FIG. 2, the illumination light is scattered by the defect, and a part of the scattered light returns to the objective lens 20. The objective lens 2o and the lens 22 constitute an imaging system that images the surface of the inspected object 11 onto the one-dimensionally arrayed photodetector 23. The objective lens 2o and the lens 22 constitute an imaging system that images the surface of the inspected object 11 on the one-dimensionally arrayed photodetector 23. A spot is formed on the one-dimensional array photodetector 23, where the focal length of the objective lens 20 is f1==4.2a+, and the focal length of the lens 22 is f2=
1 on the inspection object 11 by using a lens of 252j8.
A μm defect is observed as a 60 μm bright spot on the one-dimensional array photodetector 23. If this one-dimensional array photodetector 23 has an element pitch of 60 μm and an element number of 32,
Since one element of the photodetector 23 corresponds to 1 μm on the object 11 to be inspected, by extracting defect signals from each element of the photodetector 23 individually, a linear area of 32 μm can be separated by 1 μm.
Can be inspected simultaneously in μm.
この一次元配列光検出器２３によって検査される被検査
物１１の表面上の直線の領域を、その半径方向になるよ
うに一次元配列光検出器２３を配置すれば、被検査物１
１０回転によって第３図に示す様に帯状の部分を走査す
ることになるため、被検査物１１０表面を飛び越しする
ことなく検査するためには、半径方向の送りピッチを３
２μｍとす゛ればよく、これによってａ５０ｒＰｎで回
転している直径３００ＩＬＩｈ〜１ｏＯＪｏ＆の被検査
物１１の検査を約７分に短縮できる。If the one-dimensional array photodetector 23 is arranged so that the linear area on the surface of the inspection object 11 to be inspected by the one-dimensional array photodetector 23 is in the radial direction, the inspection object 11 can be inspected by the one-dimensional array photodetector 23.
Since a strip-shaped portion is scanned as shown in FIG. 3 by 10 rotations, in order to inspect the surface of the object 110 to be inspected without skipping over it, the feed pitch in the radial direction must be set to 3.
2 μm is sufficient, and thereby the inspection of the object 11 to be inspected, which is rotating at a50rPn and has a diameter of 300ILIh to 10OJo&, can be shortened to about 7 minutes.
ところで対物レンズ２ｏとし／ズ２２により被検査物１
１の欠陥による散乱光を一次元配列光検出器２３に正確
に結像させるためには、対物レンズ２ｏの前焦点位置が
被検査物１１０表面の位置になければならない。しかし
回転する被検査物１１は面振れなどが原因で上下に変動
しているため、対物レンズ２０はその上下変動に追従し
て上下に移動しなければならない。By the way, the object to be inspected 1 is
In order to accurately image the scattered light caused by the defect 1 on the one-dimensional array photodetector 23, the front focal position of the objective lens 2o must be at the surface of the object to be inspected 110. However, since the rotating inspection object 11 is vertically fluctuating due to surface wobbling or the like, the objective lens 20 must be moved vertically to follow the vertical fluctuation.
フォーカス制御用の光源２４（例えば波長λ＝７８ Ｑ
ｎｍのＧａＡｌＡｓ半導体レーザー）を出射した光は、
対物レンズの後側焦点位置に焦束させるだめのレンズ２
５を通過した後、λ”７８０ｎｍ反射、λ＝＝６３３ｎ
ｍ透過の特性を持つダイクロイックミラー２６によシ対
物レンズ１１の方向に反射する。対物レンズ１１の後側
焦点で集束した光は第４図Ａに示す様にレンズ２０の中
心軸に平行に中心からずれた部分に入射させる。この光
は対物レンズ２０を出た後に平行光となって被検査物１
１で反射し、再び対物レンズ２０に戻り、ダイクロイッ
クミラー２６、ミラー２７によってレンズ２８に入射す
る。光はレンズ２８によって２素子光検出器２９上に第
４図Ｂに示す様なスポットを作る。このスポット位置を
対物レンズ２０の前焦点位置と被検査物１１の位置が一
致しているときに中央に来るように調整しておくと、被
検査物１１が上、下に変位した時、スポットは左、右に
移動するので、第４図Ｃに示す様に２素子光検出器２９
の各出力を差動増幅器４４に入れ、その出力により対物
レンズ２ｏに取付けられたボイスコイル３０等のレンズ
の上下機構を制御し、対物レンズ２ｏと被検査物１１と
の相対距離を一定にするようにフォーカス制御を行なう
。Light source 24 for focus control (for example, wavelength λ=78Q
The light emitted from the GaAlAs semiconductor laser (nm GaAlAs semiconductor laser) is
Lens 2 for focusing on the back focus position of the objective lens
After passing through 5, λ”780nm reflection, λ==633n
The light is reflected in the direction of the objective lens 11 by the dichroic mirror 26 which has the characteristic of transmitting m. The light focused at the rear focal point of the objective lens 11 is made incident on a portion of the lens 20 parallel to the central axis and offset from the center as shown in FIG. 4A. After this light exits the objective lens 20, it becomes parallel light and the object to be inspected 1
1, returns to the objective lens 20, and enters the lens 28 through the dichroic mirror 26 and the mirror 27. The light forms a spot on the two-element photodetector 29 by the lens 28 as shown in FIG. 4B. If this spot position is adjusted so that it is centered when the front focal position of the objective lens 20 and the position of the object to be inspected 11 match, then when the object to be inspected 11 is displaced upward or downward, the spot moves to the left and right, so the two-element photodetector 29 moves as shown in FIG. 4C.
The respective outputs of are input to the differential amplifier 44, and the outputs control the vertical mechanism of lenses such as the voice coil 30 attached to the objective lens 2o, and the relative distance between the objective lens 2o and the object to be inspected 11 is kept constant. Perform focus control as follows.
さて、照明光が明視野の場合、一次元配列光検出器２３
の入射光量を、欠陥の無い時に光検出器２３の飽和露光
レベルに調整しておき、欠陥による散乱のだめの検出器
出力低下率の閾値を設定し、出力が閾値以下になった素
子の有無とその数から欠陥の有無、大きさを判断する。Now, if the illumination light is bright field, the one-dimensional array photodetector 23
The amount of incident light is adjusted to the saturation exposure level of the photodetector 23 when there is no defect, and a threshold value for the detector output reduction rate due to scattering due to defects is set, and the presence or absence of an element whose output is below the threshold value is determined. The presence or absence of defects and their size are determined from the number of defects.
従って、欠陥の無い時の入射光量は飽和露光レベル以上
にしてはならない。この方法によれば、例えば０゜８μ
ｍの球状試料（ラテックス）を被検査物上に置いた場合
ＮＡ０．４程度の対物レンズで検出が可能である。Therefore, the amount of incident light when there is no defect must not exceed the saturation exposure level. According to this method, for example, 0°8μ
When a spherical sample (latex) with a diameter of m is placed on an object to be inspected, detection is possible with an objective lens having an NA of about 0.4.
ところで、暗視野照明の場合には、欠陥が存在する場合
の一次元配列光検出器２３の入射光量は、光量が閾値を
越えたかどうかで欠陥の有無を判断するため、散乱光が
検出できれば良く、その強度が飽和露光レベルを越えて
もよい。従って、その光量を充分大きくすることにより
ダイナミックレンジ即ち欠陥検出感度を大きくすること
ができる。By the way, in the case of dark-field illumination, the amount of light incident on the one-dimensional array photodetector 23 when a defect exists is determined based on whether the amount of light exceeds a threshold, so it is sufficient if scattered light can be detected. , whose intensity may exceed the saturation exposure level. Therefore, by increasing the amount of light sufficiently, the dynamic range, that is, the defect detection sensitivity can be increased.
この方法によれば、前記の球状試料をＮＡｏ、２程度の
対物レンズで検出可能である。According to this method, the spherical sample described above can be detected with an objective lens of NAo, about 2.
まだ、この試料は球状の物であったが、角のある方形に
近い欠陥などの場合には、暗視野照明による検出感度は
さらに上がる。このことから、本実施例の様に、欠陥に
よる散乱光を対物レンズの開口全部で受ける必要はなく
、レンズ開口を制限し、その部分で欠陥検出を行ない、
し／ズの他の部分を他の目的で使用することが可能とな
る。Although this sample was still spherical, detection sensitivity with dark-field illumination increases even further in the case of defects that are close to rectangular shapes with corners. For this reason, as in this embodiment, it is not necessary to receive the scattered light due to the defect through the entire aperture of the objective lens, but by limiting the lens aperture and detecting the defect in that portion.
It becomes possible to use other parts of the camera for other purposes.
第５図Ａは対物レンズを利用して暗視野照明光を得る方
法を示している。第１の実施例においては暗視野照明光
を得るため、レンズ側面にリング状の集光器２１を取付
け、これに照明用の光源から出射した光を入射するとい
う方法を採用している。しかし、この様な方法の場合、
対物レンズ付近の構成が大きくなるため、その質量が増
加し、フォーカス制御が行ないにくくなる。第５図Ａに
おいては、対物レンズ２０が投光器を兼用している。即
ち、２つのミラー１９ａ、１９ｂにより適当なビーム径
に整形された照明用の２本の平行光を対物レンズ２ｏに
対し垂直に、かつ第５図Ｂに示すように中心を含まない
部分に入射する。これにより、被検査物１１に対して斜
めに集光される照明光が得られる。例えば、対物レンズ
の焦点距離ｆ１＝４．２鵡なるレンズの場合、直径３２
μｍ以上の照明スポットを得るためには、入射ビームの
直径を１０５．７ＩＩｘｎ以下にすれば良い。この方法
によって、暗視野照明光を得るための集光器２１゜２１
′といった特別の部品を使用する必要がなくなり、対物
レンズ付近の軽量化と構造の簡素化が図れる。FIG. 5A shows a method of obtaining dark field illumination using an objective lens. In the first embodiment, in order to obtain dark-field illumination light, a ring-shaped condenser 21 is attached to the side surface of the lens, and light emitted from an illumination light source is incident on the condenser 21. However, in such a method,
Since the structure near the objective lens becomes larger, its mass increases, making focus control difficult. In FIG. 5A, the objective lens 20 also serves as a light projector. That is, two parallel lights for illumination, which have been shaped into appropriate beam diameters by two mirrors 19a and 19b, are incident perpendicularly to the objective lens 2o and into a portion not including the center as shown in FIG. 5B. do. Thereby, illumination light that is focused obliquely onto the object 11 to be inspected is obtained. For example, if the focal length of the objective lens is f1 = 4.2 mm, the diameter is 32 mm.
In order to obtain an illumination spot of μm or more, the diameter of the incident beam should be 105.7IIxn or less. By this method, the condenser 21°21 for obtaining dark field illumination light
It is no longer necessary to use special parts such as ', and the area around the objective lens can be lighter and the structure can be simplified.
第５図は照明用光源とフォーカス制御用光源を同一のも
のを使用し、単一の光源で実現したものである。第５図
において、光源１６を出た光はノ・−フミラー３１によ
り２方向に進路を分けられる０直進した光はレンズ１６
，１７、ミラー１９ａ。In FIG. 5, the same light source is used for illumination and focus control, and a single light source is used. In FIG. 5, the light emitted from the light source 16 is split into two directions by a nof mirror 31.
, 17, mirror 19a.
１９ｂより暗視野照明光となる０進路を変えた光はミラ
ー３２、対物レンズの後焦点位置に焦点のあるレンズ３
３、ミラー３４により、対物レンズ２０に斜めに入射し
てフォーカス制御用の光となり、被検査物１１表面で反
射し、対物レンズ２０、ミラー３６、レンズ２８により
２素子光検出器２９上に集光され、その出力により前例
と同様にフォーカス制御が行なえる。The light whose path has been changed from 19b to become dark field illumination light is sent to the mirror 32 and the lens 3 whose focus is at the back focal position of the objective lens.
3. By the mirror 34, the light enters the objective lens 20 obliquely to become light for focus control, is reflected on the surface of the object to be inspected 11, and is focused onto the two-element photodetector 29 by the objective lens 20, mirror 36, and lens 28. Focus control can be performed using the output as in the previous example.
また、第７図Ａの構成にすることにより暗視野照明光と
フォーカス制御用の光を兼ねることができ、光学系の構
成がより簡素化できる０第７図Ａにおいて、偏光ビーム
スプリッタ３６に入射して来る照明光はＰ偏光であり、
この偏光ビームスフ。In addition, by adopting the configuration shown in FIG. 7A, the light can be used as both dark-field illumination light and focus control light, and the configuration of the optical system can be further simplified. The illumination light that comes is P-polarized light,
This polarized beam.
リッタ３６を通過する０被検査物１１による照明光の反
射光はλ１４板３７によりＳ偏光となり、偏光ビームス
プリッタ３θで反射され、光遮板羽、。The reflected light of the illumination light from the inspection object 11 passing through the litterer 36 becomes S-polarized light by the λ14 plate 37, is reflected by the polarizing beam splitter 3θ, and is transmitted to the light shielding blade.
レンズ２８によって一方のビームが２素子光検出器２９
上にスポットを形成する０このスポットは、被検査物１
１が対物レンズ２ｏの焦点位置にあるとき、光検出器２
９中夫に形成されるように調整する。被検査物１１が対
物レンズ２０の焦点位置から上下方向に変位すると、２
素子光検出器２９上のスポットが変位の大きさに比例し
て第７，８図Ｂに示す様にスポット径を変えながら左右
に移動する。従って光検出器２９の２個の光検出素子の
出力を差動増幅器に入力することにより、被検査物１１
の変位に比例した電気信号が得られ、それによって対物
レンズを上下に移動させることによりフォーカス制御を
行なうことができる。One beam is transmitted to a two-element photodetector 29 by a lens 28.
0 This spot forms a spot on the object to be inspected 1
1 is at the focal position of the objective lens 2o, the photodetector 2
Adjust so that it is formed into a 9-year-old husband. When the inspected object 11 is displaced in the vertical direction from the focal position of the objective lens 20, 2
The spot on the element photodetector 29 moves left and right while changing the spot diameter as shown in FIGS. 7 and 8B in proportion to the magnitude of the displacement. Therefore, by inputting the outputs of the two photodetecting elements of the photodetector 29 to the differential amplifier, the
An electric signal proportional to the displacement of is obtained, and focus control can be performed by moving the objective lens up and down using the electric signal.
さて、以上述べて来た実施例においては、照明用光源か
ら出射した光の一部だけをミラー１８゜１９により反射
させて利用しているにすぎず、光の利用効率が悪い。そ
こで、光源より出る光を効率的に利用し、被検査物上で
必要な部分だけを照明するため、第８図Ａの構成の光学
系を使用する０第８図Ａにおいて、光ファイ、＜ −３
９は光源１５からの出射光を適当な径の２本のビームに
分けるもので、この光ファイ／＜ −３９の出射光はシ
リンドリカルレンズ４０．４１ａ、４１ｂとレンズ４２
ａ、４２ｂにより楕円形の平行ビームとなって対物レン
ズ２０に入射する０光フアイノ＜−３９より出射する光
の直径を０．８５ｍ、シリンドリカルレンズ４０の焦点
距離ｆ＝ＢＯｍシリンドリカルレンズ４１ａ 、４１
ｂ、レンズ４２ａ、４２ｂの焦点距離が共にｆ＝＝１０
ｍであれば、対物レンズ２ｏに入射する光は第８図Ｂの
様に０．８６Ｘ０．１０ｅ麟の楕円ビームになり、これ
が検査物１１上で第８図Ｃに示すように４μｍＸ３２μ
ｍのスポットになる。このスポットの長軸が被検査物１
１の半径方向に一致するように配置し、照明されている
部分を前記の３２素子の一次元配列光検出器２３に対応
させることにより、照明用の光源の光をほとんど無駄に
することなく、暗視野照明光を得ることができ、検出感
度の高い欠陥検査が行なえるＱところが、この照明光の
強度分布は一様でないため、例えば、照明光の最内周側
や最外周側の部分における欠陥での散乱光は、照明光の
中央部分における欠陥による散乱光より弱い０そのため
、第９図に示す様に、一次元配列光検出器２３の各素子
の出力を電気的に増幅する増幅器に対し、各素子に対応
する照明光の部分の強度に逆比例する増幅率を持たせる
得る様に増幅率を調整する。これにより、欠陥の位置に
よる検出能力の変化をなくし、均一な検出能力を得るこ
とができる０又、検出素子間の感度の不均一をも補正す
ることが可 能である。Now, in the embodiments described above, only a part of the light emitted from the illumination light source is reflected by the mirrors 18 and 19, and the light utilization efficiency is poor. Therefore, in order to efficiently utilize the light emitted from the light source and illuminate only the necessary portions of the object to be inspected, an optical system having the configuration shown in FIG. 8A is used. -3
Reference numeral 9 separates the light emitted from the light source 15 into two beams with appropriate diameters, and the light emitted from this optical fiber /< -39 is split into two beams with appropriate diameters.
a, 42b becomes an elliptical parallel beam and enters the objective lens 20. The diameter of the light emitted from the 0-light beam <-39 is 0.85 m, and the focal length of the cylindrical lens 40 is f=BOm.Cylindrical lenses 41a, 41
b, the focal lengths of lenses 42a and 42b are both f==10
m, the light incident on the objective lens 2o becomes an elliptical beam of 0.86 x 0.10 e as shown in FIG.
It becomes the m spot. The long axis of this spot is the object 1 to be inspected.
1 and the illuminated portion corresponds to the 32-element one-dimensional array photodetector 23, so that almost no light from the illumination light source is wasted. It is possible to obtain dark-field illumination light and perform defect inspection with high detection sensitivity. The light scattered by a defect is weaker than the light scattered by a defect in the central part of the illumination light. Therefore, as shown in FIG. On the other hand, the amplification factor is adjusted so that each element has an amplification factor that is inversely proportional to the intensity of the portion of the illumination light corresponding to the element. As a result, it is possible to eliminate variations in detection ability depending on the position of the defect and obtain uniform detection ability, and it is also possible to correct non-uniformity in sensitivity between detection elements.
また以上では、被検査物は回転する円盤状のものとして
話を進めてきたが、直線的に移動する被検査物に対して
も同じように表面の欠陥検査を行なうことができる。第
１０図は直線的に移動する板状の被検査物４３の表面の
欠陥検査における走査方法を示したものである。走査ス
ポットは被検査物４３の一端から他の一端に至る帯状の
領域を、例えば光学系を移動するなどして走査し、被検
査物４３はその走査に同期し、スポットが一端に到達し
た瞬間に一次元配列光検出器の素子数に対応する幅だけ
進行方向に送る。このように被検査物が板状のものであ
っても、表面欠陥検査を行なうことができる。Further, in the above discussion, the object to be inspected has been described as a rotating disk-shaped object, but the surface defect inspection can be similarly performed on an object to be inspected that moves linearly. FIG. 10 shows a scanning method for defect inspection on the surface of a plate-shaped inspection object 43 that moves linearly. The scanning spot scans a strip-shaped area from one end of the object to be inspected 43 to the other end by, for example, moving an optical system, and the object to be inspected 43 is synchronized with the scanning, and the instant the spot reaches one end. The beam is sent in the traveling direction by a width corresponding to the number of elements of the one-dimensionally arrayed photodetector. In this way, even if the object to be inspected is plate-shaped, surface defect inspection can be performed.
発明の効果
以上のように本発明は、被検査物の表面を照明する光源
と、前記光源からの出射光を前記被検査物に対し斜めに
照射し照明光とする手段と、前記被検査物の表面に存在
する欠陥による前記照明光の散乱光を受けるレンズと、
前記被検査物上に焦点位置が来る様に前記レンズのフォ
ーカス禎制御を行なう手段と前記散乱光を検出するため
の一次元配列多素子光検出器と、前記散乱光を前記一次
元配列多素子検出器上に結像する前記レンズを含む光学
的手段よりなる光学系と、前記被検査物を走査する手段
と、前記走査の幅を前記一次元配列光
要素ヂ検出器の素子数に対応させる手段を有することに
より、高い欠陥検出能力と欠陥分離能力と１を維持しつ
つ、帯状領域の走査による広範囲な領域の欠陥検査の時
間短縮を実現できる。Effects of the Invention As described above, the present invention provides a light source for illuminating the surface of an object to be inspected, a means for obliquely irradiating light emitted from the light source onto the object to be inspected, and a means for illuminating the object to be inspected. a lens that receives scattered light of the illumination light due to defects existing on the surface of the lens;
means for controlling the focusing of the lens so that the focal position is on the object to be inspected; a one-dimensional array multi-element photodetector for detecting the scattered light; and a one-dimensional array multi-element photodetector for detecting the scattered light; an optical system comprising optical means including the lens that forms an image on the detector; a means for scanning the object to be inspected; and a width of the scanning corresponding to the number of elements of the one-dimensional array of optical elements and the detector. By having this means, it is possible to shorten the time required for defect inspection in a wide area by scanning a band-shaped area while maintaining high defect detection ability and defect separation ability.
なお、本発明において、被検査物は主として円盤状のも
のについて述べたが、特に被検査物の形状を限定するも
のではなく、例えば金属板の製造工程における表面欠陥
検査のように板状の被検査物に対しても適用できるもの
である。In the present invention, the object to be inspected has mainly been described as a disk-shaped object, but the shape of the object to be inspected is not particularly limited. This can also be applied to objects to be inspected.
又、フォーカス検出手段も実施例ではオファキス検出系
を用いたが、フォーカス検出可能な方法であれば、特に
限定するものではない。又、光学的検出方法以外の方法
、例えば静電容量による検出や微量空気流を吹きつける
ことによる焦点制御であってもよく、方法を限定するも
のではない。Further, although the focus detection means used in the embodiment is an off-kiss detection system, it is not particularly limited as long as it is capable of detecting focus. Further, methods other than optical detection methods, such as detection using capacitance or focus control by blowing a small amount of air flow, may be used, and the method is not limited.
又、他の光源や光学素子についても、本発明の目的とす
る欠陥検出を実現できるものであれば、特に限定するも
のではない。Further, other light sources and optical elements are not particularly limited as long as they can realize the defect detection aimed at by the present invention.
又、照明用ビームの数、形状も限定するものではない。Further, the number and shape of the illumination beams are not limited either.
第１図は本発明の第１の実施例における光学的欠陥検査
装置の光学系統図、第２図は第１図の照明光と欠陥によ
る散乱光の様子を示した部分拡大図、第３図は第１図の
一次元配列光検出器による被検査物の走査領域を示す模
式図、第４図Ａ 、 Ｂ。
Ｃは第１図のフォーカス制御方法を示す光学系統図、ス
ポット検出説明図およびサーボ回路図、第５図Ａ、Ｂは
本発明の第２の実施例における光学的欠陥検出装置の光
学系統図および照明光と散乱光の位置関係図、第５図は
本発明の第３の実施例における光学的欠陥検査装置の光
学系統図、第７図Ａ、Ｂは本発明の第４の実施例におけ
る光学的欠陥検査装置の光学系統図およびスポット検出
説明図、第８図Ａ、Ｂ、Ｃは本発明の第５の実施例にお
ける光学的欠陥検査装置の光学系統図、照明光と散乱光
の位置関係図および被検査物上の光スポツト図、第９図
は同装置における一次元配列光検出素子の出力の補正回
路図、第１０図は本発明の第５の実施例における光学的
欠陥検出装置の模式図、第１１図は従来の光学的欠陥検
査装置の光学系統図である。
１５．２４・・・・・・光源、２０・・・・・・対物レ
ンズ、１３・・・・・・光検出器、２９・・・・・・フ
ォーカス用光検出器、２３・・・・・・一次元配列多素
子光検出器、１１・・・・・・被検査物。
代理人の氏名 弁理士 中 尾 敏 男 ほか１名第
１ 図 ノ叶−被捜★？Ｖ１５・−７１１
峨昂梵璋
２０−一一対？ｌＬンス。
２４−ｍ−７オ一杯帛ノ５Ｐ月１ヒＶ吹淳−２１１次ｔ
Ｐ、暮
第２図
第３図
第４図
＋５）
第４図
第５図
第７図
第８図
第９図
第１０図
イーー’７ｅ、原
第１１図 ３−＃’ｆ’ｌ）Ｌ＞χＵ−
−−棟験ｉすFIG. 1 is an optical system diagram of an optical defect inspection apparatus according to the first embodiment of the present invention, FIG. 2 is a partially enlarged view showing the state of the illumination light in FIG. 1 and light scattered by defects, and FIG. 3 4A and 4B are schematic diagrams showing the scanning area of the object to be inspected by the one-dimensional array photodetector in FIG. 1. C is an optical system diagram, a spot detection explanatory diagram, and a servo circuit diagram showing the focus control method in FIG. 1, and FIGS. Figure 5 is a diagram of the positional relationship between illumination light and scattered light. Figure 5 is an optical system diagram of an optical defect inspection apparatus according to the third embodiment of the present invention. Figures 7A and B are optical diagrams of the optical defect inspection apparatus according to the fourth embodiment of the present invention. FIGS. 8A, B, and C are optical system diagrams and spot detection explanatory diagrams of an optical defect inspection apparatus according to a fifth embodiment of the present invention, and the positional relationship between illumination light and scattered light. Figure 9 is a diagram of a light spot on an object to be inspected, Figure 9 is a circuit diagram for correcting the output of a one-dimensional array of photodetecting elements in the same device, and Figure 10 is a diagram of an optical defect detection device according to a fifth embodiment of the present invention. The schematic diagram, FIG. 11, is an optical system diagram of a conventional optical defect inspection device. 15.24...Light source, 20...Objective lens, 13...Photodetector, 29...Focusing photodetector, 23... ...One-dimensional array multi-element photodetector, 11...Object to be inspected. Name of agent: Patent attorney Toshio Nakao and 1 other person
1 Figure No Kano - Under investigation★? V15・-711
娨泂梵潘20-一一个? lLns. 24-m-7 O Ippai Hakuno 5P Monthly 1st V Fuki Jun-211th T
P, Figure 2, Figure 3, Figure 4 + 5) Figure 4, Figure 5, Figure 7, Figure 8, Figure 9, Figure 10 E'7e, Original Figure 11 3-#'f'l) L> χU−
---Building experience
Claims (6)
の出射光を前記被検査物に対し斜めに照射し照明光とす
る手段と、前記被検査物の表面に存在する欠陥による前
記照明光の散乱光を受けるレンズと、前記被検査物上に
焦点位置が来る様に前記レンズのフォーカス制御を行な
う手段と前記散乱光を検出するための一次元配列多素子
光検出器と、前記散乱光を前記一次元配列多素子検出器
上に結像する前記レンズを含む光学的手段よりなる光学
系と、前記被検査物を走査する手段と、前記走査の幅を
前記一次元配列多素子光検出器の素子数に対応させる手
段を有することを特徴とする光学的欠陥検査装置。(1) A light source that illuminates the surface of the object to be inspected; a means for obliquely irradiating the light emitted from the light source onto the object to be inspected; a lens for receiving scattered light of illumination light; means for controlling the focus of the lens so that the focal point is on the object to be inspected; and a one-dimensional array multi-element photodetector for detecting the scattered light; an optical system including an optical means including the lens for imaging the scattered light onto the one-dimensional array multi-element detector; a means for scanning the object to be inspected; An optical defect inspection device characterized by having means for adjusting the number of elements of a photodetector.
心を除いた一部分に入射することにより、暗視野照明光
を得るようにしたことを特徴とする特許請求の範囲第１
項記載の光学的欠陥検査装置。(2) Dark-field illumination light is obtained by making the light emitted from the light source enter the lens perpendicularly to a part of the lens excluding the center of the lens.
The optical defect inspection device described in Section 1.
元配列多素子光検出器に対応する前記被検査物表面の検
出領域を包含する楕円スポットとし、前記楕円スポット
の長軸を前記一次元配列多素子光検出器の素子数に対応
する前記被検査物上での長さにほぼ一致する様に前記照
明光を変形する光学的手段を有することを特徴とする特
許請求の範囲第２項記載の光学的欠陥検査装置。(3) The shape of the dark-field illumination light that illuminates the object to be inspected is an elliptical spot that encompasses the detection area on the surface of the object that corresponds to the one-dimensional array multi-element photodetector, and the long axis of the elliptical spot is Claims characterized by comprising an optical means for transforming the illumination light so as to substantially match the length on the object to be inspected corresponding to the number of elements of the one-dimensional array multi-element photodetector. The optical defect inspection device according to item 2.
素子間の光検出感度のばらつきとを電気的に補正し得る
手段を有することを特徴とする特許請求の範囲第１項記
載の光学的欠陥検査装置。(4) Claim 1, characterized in that the device comprises means for electrically correcting the intensity distribution of illumination light and variations in photodetection sensitivity between elements of a one-dimensionally arrayed multi-element photodetector. optical defect inspection equipment.
るための光源と兼ねる単一の光源を持つことを特徴とす
る特許請求の範囲第１項記載の光学的欠陥検査装置。(5) The optical defect inspection apparatus according to claim 1, characterized by having a single light source that serves as a light source for performing focus control and a light source for obtaining illumination light.
制御を行なう手段を有することを特徴とする特許請求の
範囲第５項記載の光学的欠陥検査装置。(6) The optical defect inspection apparatus according to claim 5, further comprising means for performing focus control by using illumination light as position detection light for an object to be inspected.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3200185A JPS61191946A (en) | 1985-02-20 | 1985-02-20 | Optical defect inspector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3200185A JPS61191946A (en) | 1985-02-20 | 1985-02-20 | Optical defect inspector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS61191946A true JPS61191946A (en) | 1986-08-26 |
Family
ID=12346659
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3200185A Pending JPS61191946A (en) | 1985-02-20 | 1985-02-20 | Optical defect inspector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61191946A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0374694A2 (en) * | 1988-12-23 | 1990-06-27 | Hitachi, Ltd. | Defect detection system and method for pattern to be inspected |
| JPH02183147A (en) * | 1989-01-09 | 1990-07-17 | Nikon Corp | Fine foreign matter inspecting device |
| FR2665259A1 (en) * | 1990-07-27 | 1992-01-31 | Giat Ind Sa | Method and apparatus for determining the quality of optical components |
| JP2010014656A (en) * | 2008-07-07 | 2010-01-21 | Mitaka Koki Co Ltd | Noncontact side-surface shape measuring apparatus |
| JP2017037042A (en) * | 2015-08-13 | 2017-02-16 | 富士ゼロックス株式会社 | Measuring device and program |
| CN114791430A (en) * | 2022-06-23 | 2022-07-26 | 广州粤芯半导体技术有限公司 | Wafer gap detection device and detection method thereof |
-
1985
- 1985-02-20 JP JP3200185A patent/JPS61191946A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0374694A2 (en) * | 1988-12-23 | 1990-06-27 | Hitachi, Ltd. | Defect detection system and method for pattern to be inspected |
| JPH02183147A (en) * | 1989-01-09 | 1990-07-17 | Nikon Corp | Fine foreign matter inspecting device |
| FR2665259A1 (en) * | 1990-07-27 | 1992-01-31 | Giat Ind Sa | Method and apparatus for determining the quality of optical components |
| JP2010014656A (en) * | 2008-07-07 | 2010-01-21 | Mitaka Koki Co Ltd | Noncontact side-surface shape measuring apparatus |
| JP2017037042A (en) * | 2015-08-13 | 2017-02-16 | 富士ゼロックス株式会社 | Measuring device and program |
| CN114791430A (en) * | 2022-06-23 | 2022-07-26 | 广州粤芯半导体技术有限公司 | Wafer gap detection device and detection method thereof |
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