JPH0799354B2 - Foreign object detection method and apparatus - Google Patents

Foreign object detection method and apparatus

Info

Publication number
JPH0799354B2
JPH0799354B2 JP61065646A JP6564686A JPH0799354B2 JP H0799354 B2 JPH0799354 B2 JP H0799354B2 JP 61065646 A JP61065646 A JP 61065646A JP 6564686 A JP6564686 A JP 6564686A JP H0799354 B2 JPH0799354 B2 JP H0799354B2
Authority
JP
Japan
Prior art keywords
light
foreign matter
subject
optical fiber
fiber bundle
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.)
Expired - Lifetime
Application number
JP61065646A
Other languages
Japanese (ja)
Other versions
JPS62223647A (en
Inventor
忠輔 棟方
嘉敏 伊藤
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
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Filing date
Publication date
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Priority to JP61065646A priority Critical patent/JPH0799354B2/en
Priority to US07/030,436 priority patent/US4827143A/en
Publication of JPS62223647A publication Critical patent/JPS62223647A/en
Publication of JPH0799354B2 publication Critical patent/JPH0799354B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/47—Scattering, i.e. diffuse reflection
    • G01N21/49—Scattering, i.e. diffuse reflection within a body or fluid
    • G01N21/51—Scattering, i.e. diffuse reflection within a body or fluid inside a container, e.g. in an ampoule
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/02—Investigating particle size or size distribution
    • G01N15/0205—Investigating particle size or size distribution by optical means
    • G01N2015/0238—Single particle scatter
    • 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
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/64—Fluorescence; Phosphorescence
    • 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
    • G01N21/94—Investigating contamination, e.g. dust
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/08—Optical fibres; light guides
    • G01N2201/0826—Fibre array at source, distributing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/08—Optical fibres; light guides
    • G01N2201/0833—Fibre array at detector, resolving

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  • 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)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
  • Weting (AREA)

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、半導体素子製造工程におけるウエツトプロセ
スで使用される各種溶液中の異物を、インライン，リア
ルタイムで計測するのに好適な異物検出方法および装置
に関する。The present invention relates to a foreign matter detection method suitable for in-line and real-time measurement of foreign matter in various solutions used in a wet process in a semiconductor device manufacturing process. And equipment.

〔従来の技術〕[Conventional technology]

半導体プロセスに限らず、一般に水や化学溶液中の異物
（通常ゴミと呼ばれている雑多な物質）は、有害である
ことはよく知られており、従つて、従来から、溶液中の
異物を検査，計測する方法及び装置は、各社が開発，商
品化してきた。It is well known that not only semiconductor processes but also foreign substances in water and chemical solutions (miscellaneous substances usually called garbage) are generally harmful. Inspection and measurement methods and devices have been developed and commercialized by various companies.

従来の異物検査装置は、その使用目的により基本原理も
多岐にわたる。従来装置の立脚原理を整理すると、主要
方式に限ると（１）光方式，（２）電気抵抗方式，
（３）超音波方式の３種類に大別できる。The conventional foreign matter inspection device has various basic principles depending on the purpose of use. When the standing principle of the conventional device is arranged, the main methods are (1) optical method, (2) electrical resistance method,
(3) It can be roughly classified into three types of ultrasonic methods.

超音波方式は、例えば特開昭57−19653号公報に記載の
如く、いわゆるソナーや超音波深傷の技法を液中異物に
適用したものであるが、異物が生物細胞の場合には超音
波の反射効率が悪く、必ずしも一般的ではない。The ultrasonic method is a method in which so-called sonar and ultrasonic deep wound techniques are applied to foreign matter in the liquid as described in, for example, JP-A-57-19653. The reflection efficiency of is poor and is not always general.

電気抵抗方式は、例えば特開昭58−53738号公報に記載
の如く、***（ピンホール）を異物が通過する時に穴の
部分の溶液を排除することに起因する溶液の電気抵抗の
増大を検知するものである。この方式は元来、血液中の
赤血球を計測するために開発された。赤血球の大きさは
ほぼ一定であるから、赤血球より少し大きい***を用い
れば、***の目づまりは生じない。ところが半導体プロ
セスに用いる溶液中の異物は大きさが一定しないから、
計測のための***が場合によつては目づまりをおこす。
そのため、異物の大きさが一定していない半導体プロセ
スに常用するには不便であり、超音波方式同様必ずしも
一般的ではない。The electric resistance method detects an increase in the electric resistance of a solution caused by eliminating the solution in the hole portion when a foreign substance passes through a small hole (pinhole), as described in JP-A-58-53738, for example. To do. This method was originally developed to measure red blood cells in blood. Since the size of red blood cells is almost constant, if a small hole slightly larger than red blood cells is used, clogging of the small holes does not occur. However, the size of foreign matter in the solution used in the semiconductor process is not constant,
The small holes for measurement sometimes cause clogging.
Therefore, it is inconvenient to be used normally in a semiconductor process in which the size of foreign matter is not constant, and is not always common like the ultrasonic method.

結局、異物検査方式として一般性が大きく、未知の大き
さの異物についても安心して用いられるのは、最初に述
べた光方式である。光方式の中を細分化すると、いくつ
かの方法があるが、ここでは、本発明と溶接な関係にあ
る二つの方法について述べる。After all, the optical system described at the beginning has a great generality as a foreign matter inspection method and can be safely used for foreign matter of unknown size. There are several methods when the optical method is subdivided. Here, two methods having a welding relationship with the present invention will be described.

光方式の注目すべき第１の方法は、例えば、特開昭51−
136475号公報に記載の如く、異物からの散乱光を検知す
るものである。第５図に散乱光を用いる装置の原理構成
を示す。A notable first method of the optical system is, for example, Japanese Patent Laid-Open No. 51-
As described in Japanese Patent No. 136475, it detects scattered light from foreign matter. FIG. 5 shows the principle configuration of an apparatus using scattered light.

第５図において、検出すべき異物1,1′（図中黒丸で示
す）は溶液２と共に特定の容器３に移入される。この溶
液２を加圧などの適当な手段（表示せず）で、ノズル3a
を通して細い噴射流２′とする。噴射流２′は受容器４
に入り、通常は廃棄される。異物量が比較的少ない溶液
（例えば半導体プロセスで最も多く用いられる純水）の
場合、噴射流２′の直径を数100μｍとすれば、異物1,
1′は第５図に示すように１列に並んだ状態で溶液２と
共に噴射される。従つて、噴射流２′と直交して、光ビ
ーム５を噴射流２′に照射しておくと、異物１は個別に
光ビーム５の照射を受けることになる。光ビーム５は、
レーザなどの光源からの光線５′をレンズ６で収束して
形成している。In FIG. 5, the foreign matter 1, 1 ′ (indicated by a black circle in the figure) to be detected is transferred into the specific container 3 together with the solution 2. This solution 2 is applied to the nozzle 3a by an appropriate means such as pressurization (not shown).
To form a thin jet flow 2 '. Jet stream 2'is receiver 4
Enter and are usually discarded. In the case of a solution with a relatively small amount of foreign matter (for example, pure water that is most often used in the semiconductor process), if the diameter of the jet stream 2'is several 100 μm, the foreign matter 1,
1'is jetted together with the solution 2 in a state of being lined up in one line as shown in FIG. Therefore, if the light beam 5 is irradiated onto the jet flow 2 ′ at right angles to the jet flow 2 ′, the foreign matter 1 is individually irradiated with the light beam 5. The light beam 5 is
A light beam 5'from a light source such as a laser is converged and formed by a lens 6.

第５図において、光ビーム５が異物１に照射されると、
二つの違つた現象が発生する。第１は、光ビーム５を形
成している光子が、異物１の表面で散乱し、光ビーム５
の進行方向とは違つた方角にいわゆる散乱光７が放射さ
れる。第２は、光ビーム５がその進行を妨げられて、す
なわち遮断されて、噴射流２′の右方に透過できなくな
る。In FIG. 5, when the light beam 5 irradiates the foreign matter 1,
Two different phenomena occur. First, the photons forming the light beam 5 are scattered on the surface of the foreign matter 1 and
The so-called scattered light 7 is emitted in a direction different from the traveling direction of. Secondly, the light beam 5 is blocked in its travel, i.e. blocked, and cannot be transmitted to the right of the jet stream 2 '.

上に述べた散乱光７は異物１の存在により発生するか
ら、異物１が受容器４に向つて流れ去ると散乱光７は消
滅する。従つて、散乱光７を光検知器８で検知すれば、
異物１の通過を検出したことになる。Since the scattered light 7 described above is generated due to the presence of the foreign matter 1, when the foreign matter 1 flows away toward the receptor 4, the scattered light 7 disappears. Therefore, if the scattered light 7 is detected by the photodetector 8,
The passage of the foreign material 1 is detected.

第６図（ａ）には、上記のようにして得られる異物１か
らの散乱光信号を電気信号波形に直した例を示す。同図
には３個の異物１を検知した例を示す。このように、散
乱光強度を電気パルスに変換すれば、良く知られた電気
信号処理技術を用いて、パルス数を計数し、異物１の個
数を計測することができる。溶液２を特定体積だけ用い
れば、結局、単位体積当りの異物数を定量的に知ること
ができる。FIG. 6 (a) shows an example in which the scattered light signal from the foreign material 1 obtained as described above is converted into an electric signal waveform. The figure shows an example in which three foreign substances 1 are detected. In this way, if the scattered light intensity is converted into electric pulses, the number of pulses can be counted and the number of foreign particles 1 can be measured using a well-known electric signal processing technique. If only the specific volume of the solution 2 is used, the number of foreign matters per unit volume can be quantitatively known.

光方式の第２の方法は光遮断方法と呼ばれ、透過光を検
知する。この方法の原理を、再び第５図を用いて述べ
る。The second optical method is called a light blocking method and detects transmitted light. The principle of this method will be described again with reference to FIG.

第５図において、噴射流２′中に異物１が存在しない場
合を想定すると、障害物が存在しない為、光ビーム５は
噴射流２′を透過して、光ビーム５″を形成する。光検
知器９を用いて透過光ビーム５″を検知すると、異物１
の登場で、光ビーム５″の光量は減少する、もしくは光
ビーム５″が遮断されることは明らかである。すなわ
ち、検出器９の出力波形は、第６図（ｂ）に示すよう
に、散乱光の発生に呼応して減少する。第６図（ｂ）に
は、３個の異物が光ビーム５をよぎつた場合に対応して
いる。この透過光信号は明らかに、第６図（ａ）に示す
散乱光信号波形と等価であり、これ迄の説明から理解さ
れるように、等価光信号からも溶液２中の異物数を求め
ることができる。In FIG. 5, assuming that the foreign matter 1 does not exist in the jet stream 2 ', since there is no obstacle, the light beam 5 passes through the jet stream 2'and forms a light beam 5 ". When the transmitted light beam 5 ″ is detected by the detector 9, the foreign matter 1
With the advent of, it is clear that the light quantity of the light beam 5 ″ is reduced or the light beam 5 ″ is blocked. That is, the output waveform of the detector 9 decreases in response to the generation of scattered light, as shown in FIG. 6 (b). FIG. 6 (b) corresponds to the case where three foreign particles cross the light beam 5. This transmitted light signal is obviously equivalent to the scattered light signal waveform shown in FIG. 6 (a), and as can be understood from the above description, the number of foreign matters in the solution 2 can be obtained from the equivalent light signal. You can

第７図（ａ）には、通過光を利用して異物を検知する他
の従来例を示す。これは、特開昭50−11290号公報に記
載されている如く、汚水を清浄化する沈殿槽に適用した
ものである。第５図に示す方法は対象溶液を小量だけ抜
き取つて、実プロセスから離れて、いわゆるオフライン
（off−line）で計測するものであるが、当然ながら、
実時間計測でないという欠点を有している。これに対し
て、第７図（ａ）に示す方法は実時間計測を可能にした
ものである。FIG. 7 (a) shows another conventional example of detecting foreign matter by using passing light. This is applied to a settling tank for cleaning sewage, as described in JP-A-50-11290. The method shown in FIG. 5 is a method in which a small amount of the target solution is sampled, and the measurement is performed off-line apart from the actual process, but of course,
It has the drawback of not being a real-time measurement. On the other hand, the method shown in FIG. 7 (a) enables real-time measurement.

第７図（ａ）において、沈殿槽10内に溶液２があり、異
物1,1′が存在している。時間の経過と共に、槽10の上
槽部にあつた異物１′は、槽10の底の方に落下沈殿す
る。In FIG. 7 (a), the solution 2 is present in the settling tank 10 and the foreign matter 1, 1 ′ is present. With the lapse of time, the foreign matter 1 ′ that has come into contact with the upper tank portion of the tank 10 falls and settles toward the bottom of the tank 10.

槽10は通常強化樹脂あるいは金属などの不透明物質で形
成されているため、外部から光ビームを導入できない。
そのため、槽10の側壁の一部分に穴をあけて、透明物質
（例えばアクリルなど）を充填し、窓11,11′を形成し
ておく。このようにすれば、光ビーム５をして槽10内の
溶液２中を貫通させることができ、もし、光ビーム５と
異物１とが交差すると、透過光ビーム５″の光量が減少
する。その結果光検知器９からは第７図（ｂ）に示すよ
うに異物に対応して減少した出力がえられ、既に説明し
た原理により、異物数を計測することができる。なお、
光ビーム５′は光ファイバ12で槽10の近傍迄伝送されて
おり、光ビーム５はレンズ６で形成される。Since the tank 10 is usually made of an opaque material such as a reinforced resin or a metal, a light beam cannot be introduced from the outside.
Therefore, a hole is made in a part of the side wall of the tank 10 and a transparent material (for example, acrylic resin) is filled therein to form the windows 11 and 11 '. In this way, the light beam 5 can be penetrated through the solution 2 in the tank 10, and if the light beam 5 and the foreign matter 1 intersect, the light amount of the transmitted light beam 5 ″ is reduced. As a result, a reduced output corresponding to the foreign matter is obtained from the photodetector 9 as shown in Fig. 7 (b), and the number of foreign matter can be measured according to the principle already described.
The light beam 5'is transmitted by the optical fiber 12 to the vicinity of the tank 10, and the light beam 5 is formed by the lens 6.

〔発明が解決しようとする問題点〕[Problems to be solved by the invention]

溶液中の異物を計測する従来の方法及び装置は工業界の
要所で利用されているはいるものの、半導体プロセスへ
の適用を考えたときには、いくつかの欠点を有する。Although the conventional method and apparatus for measuring foreign matter in a solution are used in key points in the industry, they have some drawbacks when considered for application to a semiconductor process.

第１の欠点は、実時間計測でないことである。例えば、
第５図に示した光散乱方法もしくは光遮断方法の場合
は、小量の溶液２を採取して計測装置内の容器３に入れ
て計測する。その間、プロセス中の溶液自体では刻々に
異物数が変化することになり、異物計測が終了した段階
では、既にプロセス中の異物数は変つてしまつているこ
とになる。第７図（ａ）に示す光遮断方法では実時間計
測とは云うものの、沈殿現象に適用して意味があるので
あつて、半導体プロセスのように溶液がかくはんされて
いる場合には同一異物を多重計測することになり、使え
ない。いずれにせよ、異物１を時系列的に一個，一個識
別して電気パルスに変換する従来の方式は、原理的に実
時間計測ができないことは明らかである。The first drawback is that it is not real-time measurement. For example,
In the case of the light scattering method or the light blocking method shown in FIG. 5, a small amount of the solution 2 is sampled and put in the container 3 in the measuring device for measurement. During that time, the number of foreign particles in the solution itself during the process changes every moment, and the number of foreign particles in the process has already changed at the stage when the measurement of the foreign particles ends. Although the light blocking method shown in FIG. 7 (a) is called real-time measurement, it has meaning when applied to the precipitation phenomenon. Therefore, when the solution is agitated as in the semiconductor process, the same foreign matter is removed. This is a multiple measurement and cannot be used. In any case, it is clear that the conventional method of identifying one foreign object 1 in time series and converting it into an electric pulse cannot measure in real time in principle.

第２の欠点は、第１の欠点と密接に関連するが、従来方
式は“その場”（in situ）計測でないことである。例
えば、第７図（ａ）で、異物１の存在密度は、沈殿槽10
の底に近い程大きい。最終的には、沈殿槽10の上面近傍
では異物１が殆ど存在せず、いわゆるうわずみの比較的
きれいな溶液２がえられる。従つて槽10の底部の異物１
を知る意味では、槽10の底部にも第７図（ａ）に示すよ
うな透過光検出部を設ける必要がある。このことは、沈
殿槽10を追加加工することを意味し、工業的には大きな
損失となる。このように、任意の部分での“その場”計
測は、従来方式を用いる限り、事実上できない。任意の
部分から採取した溶液を第５図に示すような方法で計測
することは可能であるが、沈殿のように時々刻々に状態
が変化する対象の場合は、各時間に対応した標本溶液を
多種類採取しておく必要があり、結果がえられる迄に多
大の時間と労力とを有し、実用的ではない。したがつて
本発明の目的は上に述べた従来方式の二つの重大な欠点
も除去し、実時間計測とその場計測を可能ならしめる異
物検出方法および装置を提供することにある。The second drawback, which is closely related to the first one, is that the conventional method is not "in situ" measurement. For example, in FIG. 7 (a), the existence density of the foreign matter 1 is
The nearer it is to the bottom, the larger. Eventually, there is almost no foreign matter 1 in the vicinity of the upper surface of the settling tank 10, and a so-called relatively clean solution 2 is obtained. Therefore, the foreign matter 1 at the bottom of the tank 10
In order to know the above, it is necessary to provide a transmitted light detecting section as shown in FIG. This means that the precipitation tank 10 is additionally processed, which is a large loss industrially. Thus, "in-situ" measurement at any part is virtually impossible as long as the conventional method is used. It is possible to measure the solution taken from an arbitrary part by the method shown in Fig. 5, but in the case of a subject whose state changes momentarily like precipitation, use a sample solution corresponding to each time. It is necessary to collect many kinds of samples, and it takes a lot of time and labor to obtain the results, which is not practical. Therefore, an object of the present invention is to eliminate the two serious drawbacks of the conventional method described above, and to provide a foreign matter detection method and apparatus that enable real-time measurement and in-situ measurement.

〔問題点を解決するための手段〕[Means for solving problems]

従来方式の第１の問題点である実時間計測を達成するた
めには、従来方式で用いられていた、異物の個別係数を
やめて、新しい係数方法を採用せねばならない。この目
的のため、本発明では、多数の異物を同時に計測する。
即ち、特定体積中に存在する複数の異物からの光散乱信
号を光学的に加算し、該加算信号を一つの光検知器で検
知する。In order to achieve the first problem of the conventional method, that is, the real-time measurement, it is necessary to stop the individual coefficient of the foreign material used in the conventional method and adopt a new coefficient method. For this purpose, the present invention simultaneously measures a large number of foreign substances.
That is, light scattering signals from a plurality of foreign substances existing in a specific volume are optically added, and the added signal is detected by one photodetector.

従来方式の第２の問題点であるその場計測に関しては、
複数の異物に光を照射し、該異物からの散乱光を集光す
る部分を一体化かつ小型化し、これを対象溶液中に配置
してその目的を達する。この目的を達するために本発明
は光学フアイバを採用する。すなわち、対象溶液中に照
射光を導入し、かつ異物からの散乱光を溶液外に取り出
すために、光学フアイバ束（複数の光学フアイバ素線）
を用いる。Regarding in-situ measurement, which is the second problem of the conventional method,
The object is achieved by irradiating a plurality of foreign substances with light and integrating and miniaturizing a portion for collecting scattered light from the foreign substances, and arranging this in a target solution. To this end, the present invention employs an optical fiber. That is, in order to introduce the irradiation light into the target solution and to take the scattered light from the foreign matter out of the solution, an optical fiber bundle (a plurality of optical fiber strands) is used.
To use.

理解を深めるために、第４図を用いて、本発明の基本原
理を述べる。同図で矢印13は異物を照射するための照射
光ビームの進行方向を示し、その本数は相対的な光量を
意味している。面ABCDとそれに対向した面Ａ′Ｂ′Ｃ′
Ｄ′で規定される実線表示の直方体は、照射光ビームが
存在する領域を示している。照射光線は矢印14の方向に
進行するが、今上記直方体中に異物が存在すると光は遮
断されるから、光量は減少する（矢印14の本数が２本し
かないのは減少を表現している；矢印13は３本あること
に注意）。もし、異物が面Ｅ′Ｆ′Ｇ′Ｈ′と面Ｅ″
Ｆ″Ｇ″Ｈ″との間に存在すると仮定すると、異物から
の散乱光は矢印15の方向に放射される。For a better understanding, the basic principle of the present invention will be described with reference to FIG. In the figure, arrow 13 indicates the traveling direction of the irradiation light beam for irradiating the foreign matter, and the number thereof means the relative light amount. Face ABCD and face A'B'C 'opposite it
A solid-line-displayed rectangular parallelepiped defined by D'indicates a region where the irradiation light beam exists. The irradiation light travels in the direction of the arrow 14, but if there is a foreign substance in the rectangular parallelepiped, the light is blocked, so the amount of light decreases (the fact that there are only two arrows 14 represents a decrease). ; Note that there are three arrows 13). If the foreign matter is surface E'F'G'H 'and surface E "
Assuming that it exists between F "G" H ", the scattered light from the foreign matter is emitted in the direction of arrow 15.

当然ながら、上記空間に異物の数が多いと、散乱光が増
大する。従つて、矢印15に進む散乱光強度を光検知器で
測定すると、注目している空間の異物数を知ることがで
き、その空間の体積が分つていれば、単位体積当りの異
物数を知ることが可能となる。As a matter of course, when the number of foreign matters in the space is large, scattered light increases. Therefore, by measuring the scattered light intensity proceeding to arrow 15 with a photodetector, the number of foreign matter in the space of interest can be known.If the volume of the space is known, the number of foreign matter per unit volume can be calculated. It becomes possible to know.

照射光方向と散乱光方向とのなす角θは、例えば90゜が
有効であるが０゜〜180゜の範囲で選択可能である。The angle θ formed by the irradiation light direction and the scattered light direction is effectively 90 °, for example, but can be selected in the range of 0 ° to 180 °.

〔作用〕[Action]

本発明の第１の技術手段は、複数の異物からの散乱光を
同時に計測することであるから、従来方式のような異物
の時系列的配列動作は一切不要である。例えば、100個
の異物を同時に認識するから、応答時間が、例えば、１
μｓの光検知器（従来の光電子増倍管はこの好例であ
る）を用いれば、事実上瞬時に計測は終了する。The first technical means of the present invention is to measure scattered light from a plurality of foreign matters at the same time, and thus the time-sequential arrangement operation of the foreign matters unlike the conventional method is completely unnecessary. For example, since 100 foreign objects are recognized at the same time, the response time is, for example, 1
With a μs photodetector (a conventional photomultiplier tube is a good example of this), the measurement is virtually instantly terminated.

本発明の第２の技術手段は、光照射部と散乱光集光部と
を小型一体化してあるため、この部分を対象溶液中の任
意の部分に設置できる。例えば、沈殿槽の上部，中部，
底部たるを問わない。あるいは外部からは見えない凹部
にでもセツトできる。According to the second technical means of the present invention, since the light irradiation section and the scattered light condensing section are integrated in a small size, this section can be installed at an arbitrary section in the target solution. For example, the top, middle of the settling tank,
It does not matter if it is the bottom. Alternatively, it can be set in a recess that cannot be seen from the outside.

上記のように、任意の場所にセツトできるという本発明
の作用は、光フアイバによつて照射光及び散乱光を伝送
していることに起因している。よく知られているよう
に、光フアイバは自由に曲折できるから、光の搬送を自
在の方角に設定できる。As described above, the effect of the present invention that the optical fiber can be set at an arbitrary location is due to the fact that the irradiation light and the scattered light are transmitted by the optical fiber. As is well known, since the optical fiber can be bent freely, the light can be conveyed in any direction.

〔実施例〕〔Example〕

第１図に本発明の一実施例要部を、第２図に本発明の他
の実施例要部を示す。FIG. 1 shows an essential part of one embodiment of the present invention, and FIG. 2 shows an essential part of another embodiment of the present invention.

第１図において、対象とする溶液中の異物群1aを点の集
合で示す。異物は溶液全体に存在するが、光学的に検知
領域が限定されるので、第１図には簡単のため、測定対
象領域内の異物群1aのみを示す。In FIG. 1, the foreign matter group 1a in the target solution is shown by a set of points. Although the foreign matter exists in the entire solution, the detection area is optically limited, and therefore only the foreign matter group 1a in the measurement target area is shown in FIG. 1 for simplicity.

異物群1aには矩形断面を有する光ビーム5aが照射され
る。この光ビーム5aはいわゆる円筒レンズ6aで形成され
るが、この照射光は光フアイバ束16で供給される。異物
群1aからの散乱光ビーム7aは円筒レンズ6bで集光され、
フアイバ束17に入り、溶液外に伝送される。円筒レンズ
6a,6b及び光フアイバ束16,17の先端部は保持箱18を用い
て光学的に定められた位置に固定される。The foreign matter group 1a is irradiated with a light beam 5a having a rectangular cross section. This light beam 5a is formed by a so-called cylindrical lens 6a, and this irradiation light is supplied by the optical fiber bundle 16. The scattered light beam 7a from the foreign matter group 1a is condensed by the cylindrical lens 6b,
It enters the fiber bundle 17 and is transmitted outside the solution. Cylindrical lens
The tips of the fiber bundles 6a and 6b and the optical fiber bundles 16 and 17 are fixed to an optically determined position by using a holding box 18.

第１図に示すような、フアイバ束16,17、円筒レンズ6a,
6b、保持箱18からなる部分は例えば30mm立方程度に小型
化できるから、この部分（以下モニタヘツド、もしくは
単にヘツドと呼ぶ）を対象溶液中に入れてやれば、散乱
光ビーム7aと照射光ビーム5aとの軌跡の交差する領域に
ある複数異物を識別することができる。異物が存在しな
い場合は散乱光は零であることは云う迄もない。As shown in FIG. 1, the fiber bundles 16 and 17, the cylindrical lens 6a,
6b, since the part consisting of the holding box 18 can be miniaturized to, for example, about 30 mm cubic, if this part (hereinafter referred to as a monitor head, or simply head) is put in the target solution, the scattered light beam 7a and the irradiation light beam 5a It is possible to identify a plurality of foreign substances in the area where the loci of and intersect. It goes without saying that the scattered light is zero when no foreign matter is present.

本発明においては、従来方式と違つて、異物を個別的に
は計数しない。従つて散乱光強度からすぐに、注目領域
中の異物数を知ることはできない。そのため、単位体積
当りの異物数の既知な溶液を作つて、散乱光強度と異物
密度との関係を較正して用いる。この較正は、モニタヘ
ツドの形状が変らぬ限り、どのモニタヘツドに対しても
成立つから、特に問題はない。In the present invention, unlike the conventional method, the foreign matter is not counted individually. Therefore, the number of foreign substances in the region of interest cannot be known immediately from the scattered light intensity. Therefore, a known solution of the number of foreign matters per unit volume is prepared, and the relationship between the scattered light intensity and the foreign matter density is calibrated and used. This calibration is valid for any monitor head as long as the shape of the monitor head does not change, so there is no particular problem.

第２図に示す本発明の他の実施例は、第１図に示す実施
例と基本的には変らないが、二者の相違点は測定感度の
違いにある。第２図に示す実施例では、第１図に示す例
よりも、約２倍計測感度が上昇している。すなわち、照
射光ビーム5aによつて発生する散乱光を鏡19aのみなら
ず、鏡19bをも用いて反射させ、フアイバ束17に導入し
ている。鏡19bがなくても、本実施例は動作可能である
が、その場合には、鏡19bの方位に向う散乱光は、フア
イバ束17に導入されることなく失われる。しかし、鏡19
bにより、失われる筈の散乱光は反射されて鏡19aに入
り、ここで90゜反射されて円筒レンズ6bに入り、有効に
フアイバ束17に導かれる。The other embodiment of the present invention shown in FIG. 2 is basically the same as the embodiment shown in FIG. 1, but the difference between the two lies in the difference in measurement sensitivity. In the embodiment shown in FIG. 2, the measurement sensitivity is about twice higher than that in the example shown in FIG. That is, the scattered light generated by the irradiation light beam 5a is reflected not only by the mirror 19a but also by the mirror 19b and introduced into the fiber bundle 17. This embodiment can operate without the mirror 19b, but in that case scattered light directed in the direction of the mirror 19b is lost without being introduced into the fiber bundle 17. But the mirror 19
By b, the scattered light which should be lost is reflected and enters the mirror 19a, where it is reflected by 90 ° and enters the cylindrical lens 6b, and is effectively guided to the fiber bundle 17.

上に述べた二つの実施例では、いずれも散乱光を検出し
た。しかし、異物検知の目的では、透過光を用いてもよ
いわけで、このことは、ヘツドの簡単な変更で容易に実
施可能であるから、詳細は省略する。In both of the two examples described above, scattered light was detected. However, transmitted light may be used for the purpose of foreign matter detection, and this can be easily performed by a simple change of the head, and therefore detailed description thereof will be omitted.

本発明では理解を早めるために照射光と散乱光との波長
は同一であるという暗黙の了解のもとに説明を続けてき
た。しかし、本発明は蛍光検知にも使用できることは明
らかである。例えば、波長400nm程度の照射光によつ
て、約600nm程度の蛍光を検知することにより、フオト
レジストの粒子の検知が可能である。In the present invention, the description has been continued with the implicit understanding that the wavelengths of the irradiation light and the scattered light are the same in order to speed up understanding. However, it is clear that the present invention can also be used for fluorescence detection. For example, the particles of the photoresist can be detected by detecting the fluorescence of about 600 nm with the irradiation light of the wavelength of about 400 nm.

本発明は溶液中の異物を対象に説明したが、気体あるい
は固体中の異物検査にも適用できることは明らかであ
る。Although the present invention has been described for foreign substances in a solution, it is obvious that the present invention can also be applied to foreign substance inspection in gas or solid.

蛍光を検知するにしろ、散乱光、あるいは透過光を用い
るにしろ、計測は可視域波長にまたがることが多い。従
つて、場合によつては外来光（室内照明灯光；太陽光な
ど）が混入することがある。このような場合は適当なる
フイルタを用いて、外来光の影響を除くことができる。Whether detecting fluorescence or using scattered or transmitted light, measurements often span visible wavelengths. Therefore, extraneous light (indoor lighting light; sunlight, etc.) may be mixed depending on the case. In such a case, the influence of extraneous light can be removed by using a suitable filter.

照射光は連続光であつてもよいが、太陽光などの連続光
の影響を除去する目的で、照射光を適当な周波数、例え
ば2KHzで変調し、散乱光などの信号光をよく知られてい
る位相検波増幅して検知してもよい。このようにするこ
とにより、照射光以外の外来光の効果を最小にでき、SN
比が著しく向上する。Irradiation light may be continuous light, but for the purpose of removing the influence of continuous light such as sunlight, the irradiation light is modulated at an appropriate frequency, for example 2 KHz, and signal light such as scattered light is well known. It may be detected by phase detection amplification. By doing this, the effect of extraneous light other than the irradiation light can be minimized, and the SN
The ratio is significantly improved.

第１図，第２図には、本発明の主要部であるモニタヘツ
ドのみについて示したが、第３図（ａ）には、実際のプ
ロセスに適用した例を示す。半導体プロセスは目的に応
じて多岐にわたるが、第３図（ａ）には代表例として純
水による洗浄プロセスを示す。ウエハを洗浄するための
洗浄槽20には給水パイプ21を通して波矢印22の方向から
純水が供給される。洗浄槽20からは水が矢印23,23′の
方向にあふれ出し、流し場24に落ちこみ、やがで排水さ
れる。洗浄槽20は、脚25で流し場24に固定される。洗浄
槽20の所定の場所に、既に第１図，第２図に示したモニ
タヘツド26を光フアイバ束16,17でつり下げておく。光
フアイバ束16,17は、光源，光検知器，信号表示，信号
記録等々の素子，装置を含む計測部26に直結している。FIGS. 1 and 2 show only the monitor head, which is the main part of the present invention, but FIG. 3 (a) shows an example applied to an actual process. Although there are various semiconductor processes depending on the purpose, FIG. 3A shows a cleaning process using pure water as a typical example. Pure water is supplied to a cleaning tank 20 for cleaning a wafer through a water supply pipe 21 in the direction of a wave arrow 22. Water overflows from the washing tank 20 in the directions of the arrows 23 and 23 ', falls into the sink 24, and is drained by a slag. The washing tank 20 is fixed to the sink 24 by legs 25. The monitor head 26 shown in FIGS. 1 and 2 is already hung at a predetermined position of the cleaning tank 20 with the optical fiber bundles 16 and 17. The optical fiber bundles 16 and 17 are directly connected to a measuring unit 26 including a light source, a photodetector, elements such as signal display and signal recording, and devices.

第３図（ｂ）には、散乱光強度の測定例を示す。時間t1
で洗浄槽20にウエハ（表示せず）を入れると、ウエハの
もちこむ異物により、散乱強度は増大する。一方、もち
こまれた異物は純水の供給により、槽20外に排出される
から、時間t2から、槽20内の異物は減少し始める。この
ようにして、本発明によれば、槽20内の異物数の変化を
実時間で計測できる。FIG. 3 (b) shows an example of measurement of scattered light intensity. Time t 1
When a wafer (not shown) is placed in the cleaning tank 20, the scattering intensity increases due to the foreign matter carried in the wafer. On the other hand, the foreign matter brought in is discharged to the outside of the tank 20 by the supply of pure water, so that the foreign matter in the tank 20 starts to decrease from time t 2 . In this way, according to the present invention, the change in the number of foreign matters in the tank 20 can be measured in real time.

〔発明の効果〕〔The invention's effect〕

以上述べた如く、本発明によれば、第３図（ａ），
（ｂ）に示したように、対象溶液中の異物密度変化を実
時間で計測することができる。従つて、例えば、ウエハ
洗浄などの終了を限界異物数を定めることにより定量的
に決定することができる。また、供給すべき純水の流量
の最適値を、計測結果から決定できる。従つて、本発明
を用いて、給水流量の自動制御（異物の増大につれて給
水量を増やすなど）が可能となる。上に述べた実時間
性、即応性は、従来の方式では明らかに不可能である。As described above, according to the present invention, FIG.
As shown in (b), the foreign substance density change in the target solution can be measured in real time. Therefore, for example, the end of wafer cleaning or the like can be quantitatively determined by setting the limit number of foreign matters. Further, the optimum value of the flow rate of pure water to be supplied can be determined from the measurement result. Therefore, the present invention can be used to automatically control the water supply flow rate (such as increasing the water supply amount as the amount of foreign matter increases). The real-time property and the responsiveness described above are obviously impossible with the conventional method.

ウエハ洗浄にあつては、ウエハ近傍の溶液中に異物が多
いと、この異物がウエハに再付着する。従つて、ウエハ
から遠い部分で計測しても意味がない。本発明によれ
ば、モニタヘツドをウエハ近傍に移動させることで、簡
単に目的を達することができる。In cleaning the wafer, if there are many foreign substances in the solution near the wafer, the foreign substances will reattach to the wafer. Therefore, it does not make sense to measure the distance from the wafer. According to the present invention, the purpose can be easily achieved by moving the monitor head near the wafer.

【図面の簡単な説明】[Brief description of drawings]

第１図は本発明による異物検出装置の一実施例の概略構
成図、第２図は本発明による異物検出装置の他の一実施
例の概略構成図、第３図（ａ）は本発明による異物検出
方法の適用例を示す装置構成図、第３図（ｂ）はその計
測結果を示すグラフ、第４図は本発明による異物検出装
置の原理説明図、第５図は従来方式の原理説明図、第６
図（ａ），（ｂ）は異物通過に伴う散乱光，透過光強度
の時間依存性を示すグラフ、第７図（ａ）はもう１つの
従来方式の原理説明図、第７図（ｂ）は透過光強度の時
間依存性を示すグラフである。 1a……異物群、5a……照射光（ビーム）、6a,6b……円
筒レンズ、7a……散乱光（ビーム）、16……光フアイバ
束（照射光用）、17……光フアイバ束（散乱光用）、18
……保持箱、19a,19b……鏡。FIG. 1 is a schematic configuration diagram of an embodiment of a foreign matter detection device according to the present invention, FIG. 2 is a schematic configuration diagram of another embodiment of a foreign matter detection device according to the present invention, and FIG. 3 (a) is according to the present invention. FIG. 3B is a device configuration diagram showing an application example of the foreign matter detection method, FIG. 3B is a graph showing the measurement result, FIG. 4 is a principle explanatory diagram of the foreign matter detection apparatus according to the present invention, and FIG. Figure, 6th
Figures (a) and (b) are graphs showing the time dependence of scattered light and transmitted light intensity due to the passage of foreign matter, and Fig. 7 (a) is a principle explanatory diagram of another conventional method, and Fig. 7 (b). Is a graph showing the time dependence of transmitted light intensity. 1a ... Foreign matter group, 5a ... Irradiation light (beam), 6a, 6b ... Cylindrical lens, 7a ... Scattered light (beam), 16 ... Optical fiber bundle (for irradiation light), 17 ... Optical fiber bundle (For scattered light), 18
…… Holding box, 19a, 19b …… Mirror.

Claims (6)

【特許請求の範囲】[Claims] 【請求項１】光源からの光を第１の光ファイバ束を介し
て検出すべき異物を含む被検体の内部に導入し、この導
入された光を第１のレンズを介して２次元的な拡がりを
持つ光ビームとして上記被検体の内部に照射し、この光
ビームの照射によって上記被検体の内部から放出される
光を第２のレンズを介して集光し、この集光された光を
第２の光ファイバ束を介して上記被検体の外部に設けら
れた光検出器に導いて検出することによって、上記２次
元的な拡がりを持った光ビームによって照射される測定
対象領域内に存在する複数の上記異物を同時に検出する
ようにした異物検出方法であって、上記第１および第２
の光ファイバ束の上記被検体側の端部および上記第１お
よび第２のレンズを上記測定対象領域に隣接して設けら
れた保持箱に所定の光学的位置関係を保って一体的に固
定保持した状態で上記した異物の検出を行なうことを特
徴とする異物検出方法。1. Light from a light source is introduced through a first optical fiber bundle into the inside of a subject containing a foreign substance to be detected, and the introduced light is two-dimensionally passed through a first lens. A light beam having a divergence is applied to the inside of the subject, and light emitted from the inside of the subject due to the irradiation of the light beam is condensed through a second lens, and the condensed light is collected. Existence in the measurement target area irradiated by the light beam having the two-dimensional spread by guiding the light through the second optical fiber bundle to the photodetector provided outside the subject to detect. And a second foreign matter detecting method for simultaneously detecting a plurality of the foreign matters.
The end portion of the optical fiber bundle on the object side and the first and second lenses are integrally fixed and held in a holding box provided adjacent to the measurement target region while maintaining a predetermined optical positional relationship. A foreign matter detecting method, characterized in that the above-mentioned foreign matter is detected in the above state. 【請求項２】上記した被検体の内部から放出される光
は、上記被検体中の上記異物からの散乱光もしくは蛍
光、または上記異物を透過することによって減衰された
透過光のうちのいずれか一つであることを特徴とする特
許請求の範囲第１項に記載の異物検出方法。2. The light emitted from the inside of the subject is either scattered light or fluorescence from the foreign matter in the subject, or transmitted light attenuated by passing through the foreign matter. The foreign matter detection method according to claim 1, wherein the foreign matter detection method is one. 【請求項３】上記した被検体は、検出すべき異物を含む
液体状の被検体であることを特徴とする特許請求の範囲
第１項または第２項に記載の異物検出方法。3. The foreign matter detection method according to claim 1 or 2, wherein the subject is a liquid subject containing a foreign matter to be detected. 【請求項４】光源と、該光源からの光を検出すべき異物
を含む被検体の内部に導くための第１の光ファイバ束
と、該第１の光ファイバ束からの光を２次元的な拡がり
を持つ光ビームとして上記被検体の内部の測定対象領域
に照射するための第１のレンズと、この光ビームの照射
により上記被検体内部の上記測定対象領域から放出され
る光を集光する第２のレンズと、該第２のレンズによっ
て集光された光を上記被検体の外部に導くための第２の
光ファイバ束と、上記被検体の外部に設けられ上記第２
の光ファイバ束によって上記被検体の外部に導かれた光
を検出する光検出器とを少なくとも有してなる異物検出
装置であって、上記第１および第２の光ファイバ束の上
記被検体側の端部および上記第１および第２のレンズが
上記測定対象領域に隣接して設けられた保持箱によって
互いに所定の光学的位置関係を保った状態で一体的に固
定保持されてなることを特徴とする異物検出装置。4. A light source, a first optical fiber bundle for guiding the light from the light source to the inside of a subject containing a foreign substance to be detected, and two-dimensional light from the first optical fiber bundle. A first lens for irradiating a measurement target region inside the subject as a light beam having a wide divergence, and collecting light emitted from the measurement target region inside the subject by the irradiation of the light beam. A second lens, a second optical fiber bundle for guiding the light condensed by the second lens to the outside of the subject, and the second optical fiber bundle provided outside the subject.
A photodetector for detecting the light guided to the outside of the subject by the optical fiber bundle, and the object side of the first and second optical fiber bundles. End portions and the first and second lenses are integrally fixed and held by a holding box provided adjacent to the measurement target region while maintaining a predetermined optical positional relationship with each other. Foreign matter detector. 【請求項５】上記光源は特定の周波数でもって強度変調
された光を発生する光源であり、かつ、上記光検出器は
上記被検体内部の上記測定対象領域から放出される光を
上記した特定の周波数でもって位相検波して検出するも
のであることを特徴とする特許請求の範囲第４項に記載
の異物検出装置。5. The light source is a light source that emits light intensity-modulated at a specific frequency, and the photodetector is a light source that emits light emitted from the measurement target region inside the subject. The foreign matter detecting device according to claim 4, wherein the foreign matter detecting device detects the foreign matter by phase detection with the frequency of. 【請求項６】上記した第１および第２のレンズが円筒レ
ンズであることを特徴とする特許請求の範囲第４項また
は第５項に記載の異物検出装置。6. The foreign matter detecting device according to claim 4 or 5, wherein the first and second lenses are cylindrical lenses.
JP61065646A 1986-03-26 1986-03-26 Foreign object detection method and apparatus Expired - Lifetime JPH0799354B2 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP61065646A JPH0799354B2 (en) 1986-03-26 1986-03-26 Foreign object detection method and apparatus
US07/030,436 US4827143A (en) 1986-03-26 1987-03-26 Monitor for particles of various materials

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP61065646A JPH0799354B2 (en) 1986-03-26 1986-03-26 Foreign object detection method and apparatus

Publications (2)

Publication Number Publication Date
JPS62223647A JPS62223647A (en) 1987-10-01
JPH0799354B2 true JPH0799354B2 (en) 1995-10-25

Family

ID=13292979

Family Applications (1)

Application Number Title Priority Date Filing Date
JP61065646A Expired - Lifetime JPH0799354B2 (en) 1986-03-26 1986-03-26 Foreign object detection method and apparatus

Country Status (1)

Country Link
JP (1) JPH0799354B2 (en)

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5766342A (en) * 1980-04-28 1982-04-22 Agency Of Ind Science & Technol Optical measuring method for suspension particles in medium
JPS5793240A (en) * 1980-11-29 1982-06-10 Matsushita Electric Works Ltd Light transmitting type checking device
JPS58158352U (en) * 1982-04-15 1983-10-22 松下電工株式会社 dirt detector
US4564598A (en) * 1982-07-12 1986-01-14 Syntex (U.S.A.) Inc. Limited volume method for particle counting
JPS59168346A (en) * 1983-03-15 1984-09-22 Matsushita Electric Works Ltd Device for detecting defect in veneer

Also Published As

Publication number Publication date
JPS62223647A (en) 1987-10-01

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