JPH0886738A - Method and device for measuring particulate - Google Patents
Method and device for measuring particulateInfo
- Publication number
- JPH0886738A JPH0886738A JP6220629A JP22062994A JPH0886738A JP H0886738 A JPH0886738 A JP H0886738A JP 6220629 A JP6220629 A JP 6220629A JP 22062994 A JP22062994 A JP 22062994A JP H0886738 A JPH0886738 A JP H0886738A
- Authority
- JP
- Japan
- Prior art keywords
- polarization
- light
- scattered light
- measurement target
- target space
- 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.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 14
- 239000002245 particle Substances 0.000 claims abstract description 47
- 238000006243 chemical reaction Methods 0.000 claims abstract description 18
- 230000002999 depolarising effect Effects 0.000 claims abstract description 5
- 230000010287 polarization Effects 0.000 claims description 92
- 238000005259 measurement Methods 0.000 claims description 42
- 239000010419 fine particle Substances 0.000 claims description 29
- 239000000126 substance Substances 0.000 claims description 10
- 239000000284 extract Substances 0.000 claims description 3
- 230000001419 dependent effect Effects 0.000 claims 1
- 230000003287 optical effect Effects 0.000 description 14
- 238000010586 diagram Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 3
- 230000001678 irradiating effect Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
Landscapes
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は測定対象空間の粒子にレ
ーザ光を照射し、各偏光成分毎の散乱光強度から測定対
象空間の粒子の代表的な粒子の大きさ、二次元的な粒子
濃度、粒子の屈折率等を知ることができる微粒子測定方
法及びその装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention irradiates particles in a measurement target space with a laser beam, and based on the intensity of scattered light of each polarization component, representative particle sizes of particles in the measurement target space, two-dimensional particles The present invention relates to a fine particle measuring method and apparatus capable of knowing the concentration and the refractive index of particles.
【0002】[0002]
【従来の技術】半導体集積回路の製造プロセスにおいて
は、微細な粒子が表面に付着することで、回路の欠陥と
なり、製品の歩留まりが低下する。このため、処理チャ
ンバー等の所定の系内の微粒子の粒子径や微粒子の数
(濃度)を検出する必要がある。また、その粒子の組成
を知ることがその粒子の生成原因を推察するのに有効で
ある。2. Description of the Related Art In the process of manufacturing a semiconductor integrated circuit, fine particles adhere to the surface to cause defects in the circuit and reduce the yield of products. Therefore, it is necessary to detect the particle size of fine particles and the number (concentration) of fine particles in a predetermined system such as a processing chamber. Further, knowing the composition of the particles is effective in inferring the cause of the generation of the particles.
【0003】このような微細な粒子の測定にはMieの
理論式が適用され、このMieの理論式を適用した先行
技術として特公平5−75975号公報及び雑誌(Plas
ma Sources Science and Technology 1993年 第
2巻 35〜39頁)に記載された論文がある。図4は
前記論文の概略構成を示し、レーザ光源100で生成さ
れた単一波長のレーザ光を偏光解消板101にて無偏光
のレーザ光とし、このレーザ光を測定対象空間Sに照射
する構成とし、また、測定対象空間Sの左右には照射光
軸に対して同じ光軸交角となるように2つの光学系を配
置し、各光学系を測定対象空間Sに近い方から順に、ア
パーチャ102a,102b、偏光フィルタ103a,
103b、アパーチャ104a,104b、レンズ10
5a,105b、波長選択フィルタ106a,106b
及び光電変換素子107a,107bを配置し、測定対
象空間Sからの散乱光のうち観測面に対して偏光角度が
0°の偏光成分を光電変換素子107aに、偏光角度が
90°の偏光成分を光電変換素子107bに入射せし
め、これら二偏光成分の光量の比から代表的な粒子の大
きさを求め、更に前もって作成しておいた既知のデータ
との比較により粒子濃度を求めるようにしている。ま
た、雑誌(Jpn.J.Appl.Phys.33巻 1994年 L476頁〜L4
78頁)に記載された論文がある。この論文では、ローテ
イティングアナライザと1/4波長板を用いて粒子群か
らの散乱光の偏光成分を時間的に分離し、一つの受光素
子を用いて粒子の測定を行っている。The Mie theoretical formula is applied to the measurement of such fine particles, and as a prior art to which the Mie theoretical formula is applied, Japanese Patent Publication No. 5-75975 and a magazine (Plas
ma Sources Science and Technology 1993 Vol.2, pp.35-39). FIG. 4 shows a schematic configuration of the above-mentioned paper, in which a single-wavelength laser beam generated by a laser light source 100 is made into unpolarized laser beam by a depolarizing plate 101, and this laser beam is irradiated to a measurement target space S. Further, two optical systems are arranged on the left and right of the measurement target space S so as to have the same optical axis crossing angle with respect to the irradiation optical axis, and each optical system is sequentially arranged from the side closer to the measurement target space S in the aperture 102a. , 102b, polarization filter 103a,
103b, apertures 104a and 104b, lens 10
5a, 105b, wavelength selection filters 106a, 106b
Further, the photoelectric conversion elements 107a and 107b are arranged, and among the scattered light from the measurement target space S, a polarization component having a polarization angle of 0 ° with respect to the observation plane is provided to the photoelectric conversion element 107a and a polarization component having a polarization angle of 90 ° is provided. The size of a representative particle is obtained from the ratio of the light amounts of these two polarization components by making the light incident on the photoelectric conversion element 107b, and the particle concentration is obtained by comparison with the known data created in advance. In addition, magazines (Jpn.J.Appl.Phys. 33, 1994 L476 pages-L4
There is a paper described on page 78). In this paper, the polarization component of the scattered light from the particle group is temporally separated using a rotating analyzer and a quarter-wave plate, and the particle is measured using one light receiving element.
【0004】[0004]
【発明が解決しようとする課題】半導体集積回路の製造
プロセス等において、製品歩留りを向上するには、微粒
子の粒径や数を知ることも重要であるが、当該微粒子が
何であるかを知ることで、どのプロセスで混入したかの
重要な手がかりとなり、装置やラインの改良の指針とす
ることができる。しかしながら、従来例に示される方法
では、散乱光の一部の情報(二偏光成分)のみを用いて
いた為、浮遊粒子の代表的な大きさと濃度を測定できる
だけであり、粒子の組成に係わる粒子の屈折率について
の情報を得ることはできなかった。In order to improve the product yield in the manufacturing process of semiconductor integrated circuits, etc., it is important to know the particle size and number of fine particles, but to know what the fine particles are. Thus, it becomes an important clue as to which process the mixing was carried out, and can be used as a guideline for improving the equipment and line. However, in the method shown in the conventional example, since only a part of the information (dipolarized component) of scattered light is used, only the typical size and concentration of suspended particles can be measured, and the particles related to the composition of particles can be measured. It was not possible to obtain information about the refractive index of.
【0005】更に、従来の方法では、測定できる粒子径
や粒子数は系内の1点に限定され、全体の粒子分布や系
内の平均的な粒子数を正確に測定することができない。
もっとも後者の論文では、粒子群からの散乱光の偏光成
分を利用しているが、偏光面を時間的に回転させ、1つ
の光電変換素子(フォトマル)で受光しているので、各
偏光成分測定の同時性がないものであった。また光強度
が違う信号を一つの光電変換素子で電気信号に変換する
ためダイナミックレンジが狭くなり、小さな粒子の計測
が困難である。Further, according to the conventional method, the measurable particle diameter and the number of particles are limited to one point in the system, and it is impossible to accurately measure the entire particle distribution or the average number of particles in the system.
However, in the latter paper, the polarization component of the scattered light from the particle group is used. However, since the polarization plane is temporally rotated and received by one photoelectric conversion element (Photomul), each polarization component There was no simultaneity of measurement. In addition, since signals having different light intensities are converted into electric signals by one photoelectric conversion element, the dynamic range is narrowed and it is difficult to measure small particles.
【0006】[0006]
【課題を解決するための手段】上記課題を解決すべく本
発明に係る微粒子測定方法は、3つの異なる偏光成分を
含むレーザ光を照射光として測定対象空間に照射し、こ
の測定対象空間からの散乱光を前記3つの異なる偏光成
分毎に分離し、各偏光成分毎に散乱光を光電変換素子に
入射せしめ、各偏光成分毎の散乱光強度を求め、これら
3つの散乱光強度の値から偏光パラメータを求め、この
偏光パラメータの時系列変化と予め理論的に求めておい
た既知の物質の偏光パラメータの時系列変化とを比較す
ることで、測定対象空間の微粒子を測定するようにし
た。In order to solve the above-mentioned problems, a method for measuring fine particles according to the present invention irradiates laser light containing three different polarization components as irradiation light onto a space to be measured, and measures the space from the space to be measured. The scattered light is separated for each of the three different polarization components, the scattered light for each polarization component is incident on the photoelectric conversion element, the scattered light intensity for each polarization component is obtained, and the polarization is calculated from these three scattered light intensity values. The parameters were determined, and the time series change of the polarization parameter was compared with the time series change of the polarization parameter of the known substance that was theoretically obtained in advance, so that the fine particles in the measurement target space were measured.
【0007】また、本発明に係る他の微粒子測定方法
は、所定角度の偏光成分からなる第1のレーザ光と、偏
光角度及び波長が前記第1のレーザ光と異なる第2のレ
ーザ光と、偏光角度及び波長が前記第1及び第2のレー
ザ光と異なる第3のレーザ光とを同一方向から照射光と
して測定対象空間に照射し、この測定対象空間内の所定
の平面的な領域から散乱光を取り出し、当該散乱光を偏
光成分毎の散乱光に分離して撮像素子に入射せしめ、各
偏光成分毎の散乱光強度を求め、これら3つの散乱光強
度の値から偏光パラメータを求め、この偏光パラメータ
の時系列変化と予め理論的に求めておいた既知の物質の
偏光パラメータの時系列変化とを比較することで、測定
対象空間の微粒子を特定するようにした。Another method for measuring fine particles according to the present invention is: a first laser beam composed of a polarized component having a predetermined angle; and a second laser beam having a polarization angle and a wavelength different from those of the first laser beam. The measurement target space is irradiated with a third laser beam having a polarization angle and a wavelength different from the first and second laser beams from the same direction, and scattered from a predetermined planar area in the measurement target space. The light is taken out, the scattered light is separated into scattered light for each polarization component and is made incident on the image sensor, the scattered light intensity for each polarized light component is obtained, and the polarization parameter is obtained from these three scattered light intensity values. By comparing the time series change of the polarization parameter with the time series change of the polarization parameter of a known substance that was theoretically obtained in advance, the fine particles in the measurement target space were specified.
【0008】一方、本発明に係る微粒子測定装置は、単
一の波長のレーザ光を生成するレーザ光源と、このレー
ザ光源からのレーザ光を無偏光として測定対象空間に照
射する偏光解消板と、測定対象空間からの散乱光を取り
出すアパーチャ及びレンズ系と、これらアパーチャ及び
レンズ系を透過した散乱光を3つの偏光成分毎に分離す
る偏光素子、例えば偏光フィルタまたは偏光プリズム
と、分離された3つの偏光成分の夫々が入射する第1,
第2及び第3の光電変換素子とによって微粒子測定装置
を構成した。On the other hand, the fine particle measuring apparatus according to the present invention comprises a laser light source for generating a laser beam of a single wavelength, and a depolarizing plate for irradiating the laser light from the laser light source into the space to be measured as non-polarized light. An aperture and a lens system that extracts scattered light from the measurement target space, and a polarization element that separates the scattered light that has passed through the aperture and the lens system into three polarization components, such as a polarization filter or a polarization prism, and three separated light components. The first, on which each of the polarization components is incident,
A fine particle measuring device was constituted by the second and third photoelectric conversion elements.
【0009】また、本発明に係る他の微粒子測定装置
は、所定角度の偏光成分からなる第1のレーザ光を生成
する第1のレーザ光源と、前記第1のレーザ光と偏光角
度及び波長が異なる第2のレーザ光を生成する第2のレ
ーザ光源と、前記第1及び第2のレーザ光と偏光角度及
び波長が異なる第3のレーザ光を生成する第3のレーザ
光源と、第1,第2及び第3のレーザ光を合成して照射
光として測定対象空間に照射するレンズ系と、この測定
対象空間内の所定の平面的な領域から散乱光を取り出す
レンズ系と、このレンズ系を介して取り出した散乱光か
ら波長を指標として三つの偏光成分に分離する波長選択
手段と、この波長選択手段で分離された各偏光成分毎の
散乱光が入射する第1,第2及び第3の撮像素子とによ
って微粒子測定装置を構成した。Further, another particle measuring apparatus according to the present invention is such that a first laser light source for generating a first laser light having a polarization component of a predetermined angle and a polarization angle and a wavelength of the first laser light are A second laser light source for generating a different second laser light; a third laser light source for generating a third laser light having a polarization angle and a wavelength different from those of the first and second laser lights; A lens system that synthesizes the second and third laser beams and irradiates the measurement target space as irradiation light, a lens system that extracts scattered light from a predetermined planar area in the measurement target space, and this lens system A wavelength selection unit that separates the scattered light extracted through the wavelength division unit into three polarization components using the wavelength, and the first, the second, and the third that the scattered light of each polarization component separated by the wavelength selection unit enters. Particle measuring device with image sensor Configuration was.
【0010】以上において、測定対象空間からの散乱光
を取り出すレンズ系を含む受光系は、測定対象空間の一
側に1つ配置するか、測定対象空間の両側に1つづつ配
置することができる。In the above description, one light receiving system including a lens system for taking out scattered light from the measurement object space can be arranged on one side of the measurement object space or can be arranged on both sides of the measurement object space. .
【0011】[0011]
【作用】散乱光を3つの異なる偏光成分に分離し、各偏
光成分毎の散乱光強度から時間の経過とともに変化する
粒子径と同じく時間の経過とともに変化する偏光パラメ
ータを求めてグラフ等を作成し、これと、既知の物質に
ついて作成しておいたグラフ等と比較し、同じものを選
ぶことで、系内に存在する物質が何であるかを知ること
ができる。[Operation] The scattered light is separated into three different polarization components, and the particle size that changes with the passage of time and the polarization parameter that also changes with the passage of time are obtained from the intensity of the scattered light of each polarization component, and a graph is created. By comparing this with a graph prepared for a known substance and selecting the same, it is possible to know what the substance is in the system.
【0012】[0012]
【実施例】以下に本発明の実施例を添付図面に基づいて
説明する。ここで、図1は本発明に係る微粒子測定装置
の全体構成図であり、この微粒子測定装置はレーザ光源
1で生成されるレーザ光を偏光解消板2にて無偏光のレ
ーザ光とし、このレーザ光を照射光として測定対象空間
Sに照射する。Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is an overall configuration diagram of a fine particle measuring apparatus according to the present invention. In this fine particle measuring apparatus, laser light generated by a laser light source 1 is converted into unpolarized laser light by a depolarizing plate 2, and this laser is used. The measurement target space S is irradiated with light as irradiation light.
【0013】また、測定対象空間Sの左右に照射光軸に
対して同じ光軸交角(γ)となるように2つの受光系1
0,20を配置している。尚、この光軸交角(γ)は互
いに等しいことが好ましく、更にその角度は90°であ
ることが好ましいが、予め光軸交角(γ)が判明してい
れば、光軸交角(γ)は異なっても良い。Further, two light receiving systems 1 are arranged on the left and right sides of the space S to be measured so that they have the same optical axis intersection angle (γ) with respect to the irradiation optical axis.
0 and 20 are arranged. The optical axis intersection angles (γ) are preferably equal to each other, and the angle is preferably 90 °. However, if the optical axis intersection angle (γ) is known in advance, the optical axis intersection angle (γ) is It can be different.
【0014】一方の受光系10には、測定対象空間Sに
近い側から順に、アパーチャ11、レンズ系12、アパ
ーチャ13、偏光フィルタ14、波長選択フィルタ15
及び光電変換素子16を配置し、測定対象空間Sからの
散乱光のうち観測面に対する偏光角度が45°の散乱光
のみを偏光フィルタ14にて選別して光電変換素子16
に入射せしめるようにしている。尚、波長選択フィルタ
15は照射したレーザ光以外の波長の光をカットし、S
/Nを向上させるためのものである。In one light receiving system 10, the aperture 11, the lens system 12, the aperture 13, the polarization filter 14, and the wavelength selection filter 15 are arranged in this order from the side closer to the space S to be measured.
Further, the photoelectric conversion element 16 is arranged, and among the scattered light from the measurement target space S, only the scattered light having a polarization angle of 45 ° with respect to the observation surface is selected by the polarization filter 14 and the photoelectric conversion element 16 is selected.
It is designed to be incident on. The wavelength selection filter 15 cuts light having a wavelength other than the emitted laser light,
It is for improving / N.
【0015】また、他方の受光系20には、測定対象空
間Sに近い側から順に、アパーチャ21、レンズ系2
2、アパーチャ23、集光レンズ24、偏光プリズム
(グラントムソンプリズム)25を配置し、更にこの偏
光プリズム25から分岐して波長選択フィルタ26,2
7及び光電変換素子28,29を配置している。In the other light receiving system 20, the aperture 21 and the lens system 2 are arranged in this order from the side closer to the space S to be measured.
2, an aperture 23, a condenser lens 24, and a polarization prism (Glan-Thompson prism) 25 are arranged, and further branched from this polarization prism 25, the wavelength selection filters 26, 2
7 and photoelectric conversion elements 28 and 29 are arranged.
【0016】而して、受光系20に入った散乱光は、集
光レンズ24によって再度集光され、更に偏光プリズム
25によって偏光角度0°及び90°の散乱光に分離さ
れ、更に波長選択フィルタ26を透過した後、偏光角度
0°の散乱光は光電変換素子28に入射し、偏光角度9
0°の散乱光は波長選択フィルタ27を透過した後、光
電変換素子29に入射する。The scattered light that has entered the light receiving system 20 is condensed again by the condenser lens 24 and further separated by the polarizing prism 25 into scattered light having polarization angles of 0 ° and 90 °, and further the wavelength selection filter. After passing through 26, the scattered light having a polarization angle of 0 ° is incident on the photoelectric conversion element 28 and the polarization angle of 9 °
The scattered light of 0 ° passes through the wavelength selection filter 27 and then enters the photoelectric conversion element 29.
【0017】図2は本発明に係る微粒子測定装置の他の
例を示す全体構成図であり、この微粒子測定装置は夫々
異なる波長(λ1,λ2,λ3)のレーザ光を生成するレ
ーザ光源31,32,33を備えている。レーザ光源3
1にて生成されるレーザ光λ1は観測面に対する角度が
90°の偏光成分からなり、またレーザ光源32には1
/2波長板34を付設し、レーザ光λ2の偏光成分を観
測面に対する角度が45°のものとし、更にレーザ光源
33にも1/2波長板35を付設し、レーザ光λ3の偏
光成分を観測面に対する角度が0°のものとしている。FIG. 2 is an overall configuration diagram showing another example of the fine particle measuring apparatus according to the present invention. This fine particle measuring apparatus produces laser beams of different wavelengths (λ 1 , λ 2 , λ 3 ). The light sources 31, 32 and 33 are provided. Laser light source 3
The laser light λ 1 generated at 1 is composed of a polarized light component having an angle of 90 ° with respect to the observation plane, and the laser light source 32 has 1
/ 2 wavelength plate 34 is attached, the polarization component of the laser beam λ 2 is set to an angle of 45 ° with respect to the observation plane, and the laser light source 33 is also attached with a 1/2 wavelength plate 35 to polarize the laser beam λ 3 . The component has an angle of 0 ° with respect to the observation plane.
【0018】更に、レーザ光λ1はミラー36にて反射
し、誘電体ミラー37,38を透過し、またレーザ光λ
2は誘電体ミラー37で反射し、誘電体ミラー38を透
過し、更にレーザ光λ3は誘電体ミラー38で反射して
1本のレーザ光に合成され、このレーザ光はシリンドリ
カルレンズ等のレンズ系39によってシート状等の幅を
もった照射光Lとされ、この照射光Lは測定対象空間S
に照射される。Further, the laser beam λ 1 is reflected by the mirror 36, transmitted through the dielectric mirrors 37 and 38, and the laser beam λ 1
2 is reflected by the dielectric mirror 37, is transmitted through the dielectric mirror 38, and the laser light λ 3 is reflected by the dielectric mirror 38 and is combined into one laser light. This laser light is a lens such as a cylindrical lens. Irradiation light L having a sheet-like width is formed by the system 39, and this irradiation light L is the measurement target space S.
Is irradiated.
【0019】また、測定対象空間Sの一方の側には、1
つの受光系40を配置している。この受光系40はレン
ズ系41、誘電体ミラー42,43、ミラー44、波長
選択フィルタ45,46,47及びCCD撮像素子4
8,49,50から構成されている。On one side of the space S to be measured, 1
Two light receiving systems 40 are arranged. The light receiving system 40 includes a lens system 41, dielectric mirrors 42 and 43, a mirror 44, wavelength selection filters 45, 46 and 47, and a CCD image pickup device 4.
It is composed of 8, 49 and 50.
【0020】尚、受光系は前述した如く同一観測方向に
配置されることが好ましい。即ち、照射光軸に対して同
じ光軸交角となるように配置されることが好ましい。本
実施例では図2に示したように測定対象空間Sの一方の
側に受光系を一つにまとめて配置しているので、照射光
軸に対する光軸交角が自ずと等しくなり、図1の実施例
に比べて光軸交角を等しくする必要がなくなり、好都合
である。The light receiving system is preferably arranged in the same observation direction as described above. That is, it is preferable that they are arranged so as to have the same optical axis intersection angle with respect to the irradiation optical axis. In the present embodiment, as shown in FIG. 2, since the light receiving systems are collectively arranged on one side of the measurement target space S, the optical axis crossing angle with respect to the irradiation optical axis is naturally equal to each other. This is convenient because it is not necessary to make the optical axis intersection angles equal to each other as compared with the example.
【0021】而して、レンズ系41によって測定対象空
間Sからの散乱光を所定の平面的な領域で取り出し、レ
ンズ系41を透過した散乱光のうち波長がλ1の散乱光
(偏光角度=90°)のみを誘電体ミラー42にて反射
し、S/N向上のための波長選択フィルタ45を介して
CCD撮像素子48に入射し、誘電体ミラー42を透過
した散乱光のうち波長がλ2の散乱光(偏光角度=45
°)のみを誘電体ミラー43にて反射し、波長選択フィ
ルタ46を介してCCD撮像素子49に入射し、更に誘
電体ミラー43を透過した波長がλ3の散乱光(偏光角
度=0°)をミラー44にて反射し、波長選択フィルタ
47を介してCCD撮像素子50に入射する。ところ
で、図1に示すように実施例も同様であるが、偏光角度
の組み合わせは、0°,45°,90°の場合が最も好
ましい。しかし、偏光角度の組み合わせは、この組み合
わせに限定されるものではなく、他の組み合わせでも良
い。尚、測定対象空間S中の同じ位置を撮像している撮
像素子48,49,50の画素子には同じ粒子群の散乱
光が入射するので、それぞれの偏光成分毎の散乱光強度
(I0,I45,I90)が検出され、電気的信号として演
算処理装置に送られる。Thus, the scattered light from the space S to be measured is taken out by the lens system 41 in a predetermined planar area, and the scattered light having the wavelength λ 1 out of the scattered light transmitted through the lens system 41 (polarization angle = Only 90 °) is reflected by the dielectric mirror 42, is incident on the CCD image pickup device 48 through the wavelength selection filter 45 for improving the S / N, and the wavelength of the scattered light transmitted through the dielectric mirror 42 is λ. 2 scattered light (polarization angle = 45
Scattered light having a wavelength of λ 3 (polarization angle = 0 °) after being reflected by the dielectric mirror 43, incident on the CCD image pickup device 49 via the wavelength selection filter 46, and transmitted through the dielectric mirror 43. Is reflected by the mirror 44 and is incident on the CCD image pickup device 50 via the wavelength selection filter 47. Incidentally, as shown in FIG. 1, the same applies to the embodiment, but the combination of polarization angles is most preferably 0 °, 45 °, 90 °. However, the combination of polarization angles is not limited to this combination, and other combinations may be used. Since the scattered light of the same particle group is incident on the image elements of the image pickup devices 48, 49, and 50 that image the same position in the measurement target space S, the scattered light intensity (I 0 for each polarization component) is obtained. , I 45 , I 90 ) are detected and sent to the arithmetic processing unit as electrical signals.
【0022】以上の如くして、光電変換素子16,2
8,29またはCCD撮像素子48,49,50にて検
出した偏光成分の毎の散乱光強度(I0,I45,I90)
に基づいて検出した微粒子を測定する方法を以下に述べ
る。As described above, the photoelectric conversion elements 16 and 2
8, 29 or scattered light intensity (I 0 , I 45 , I 90 ) for each polarization component detected by the CCD imagers 48, 49, 50
A method for measuring the fine particles detected based on the above will be described below.
【0023】一般に、照射光の強度をIとすると、散乱
光の強度は偏光角度(x)をパラメータとして以下の
(数1)にて表わされる。Generally, when the intensity of the irradiation light is I, the intensity of the scattered light is expressed by the following (Equation 1) using the polarization angle (x) as a parameter.
【数1】 上記(数1)において、偏光角度(x)が既知であれ
ば、未知数はI、a、bの3つになる。そこで、少なく
とも3つの偏光角度(x)に対して散乱光強度の時間推
移を測定すれば、I、a、bの時間推移が求まり、これ
らa、bを用いて偏光パラメータ(△,Ψ)を求めるこ
とができる。即ち、(数1)からx=0°,45°,9
0°の時の散乱光を求めると、以下の(数2)、(数
3)及び(数4)になる。[Equation 1] In the above (Equation 1), if the polarization angle (x) is known, there are three unknowns I, a, and b. Therefore, if the time transition of the scattered light intensity is measured for at least three polarization angles (x), the time transitions of I, a, and b can be obtained, and the polarization parameters (Δ, Ψ) can be calculated using these a and b. You can ask. That is, from (Equation 1), x = 0 °, 45 °, 9
When the scattered light at 0 ° is obtained, the following (Equation 2), (Equation 3) and (Equation 4) are obtained.
【数2】 [Equation 2]
【数3】 (Equation 3)
【数4】 (数2)及び(数4)において、S1,S2はMieの理
論式によって導かれる振動関数で、入射光の振動面に垂
直な成分及び水平な成分を表わしており、測定対象の粒
子径、粒子の屈折率、入射光の波長(ここでは既知の
値)をパラメータとしている。そこで、以下の(数5)
及び(数6)が導かれる。[Equation 4] In (Equation 2) and (Equation 4), S 1 and S 2 are vibration functions that are guided by Mie's theoretical formula, and represent the vertical component and the horizontal component of the vibration plane of the incident light. The parameters are the diameter, the refractive index of the particles, and the wavelength of incident light (known value here). Therefore, the following (Equation 5)
And (Equation 6) are derived.
【数5】 (Equation 5)
【数6】 これらから偏光パラメータ(△,Ψ)は以下の(数7)
及び(数8)で表わされる。(Equation 6) From these, the polarization parameters (△, Ψ) are
And (Equation 8).
【数7】 (Equation 7)
【数8】 一方、Mieの理論式を用いると、偏光パラメータ
(△,Ψ)は以下の(数9)に示すような、粒子の代表
的な大きさ、粒子の大きさの分布の広がり、粒子の屈折
率等の関数として表わすことができる。[Equation 8] On the other hand, when the Mie theoretical formula is used, the polarization parameter (Δ, Ψ) is represented by the following (Equation 9), and the typical size of the particle, the spread of the particle size distribution, the refractive index of the particle Can be expressed as a function of
【数9】 [Equation 9]
【0024】したがって、実際の測定によって求めた偏
光パラメータ(△,Ψ)の時系列変化を、Mieの理論
式から求めた偏光パラメータ(△,Ψ)の時系列変化と
比較することにより、測定した粒子の屈折率等を検出
し、当該微粒子がどのような物質からできているかを知
ることができる。Therefore, it was measured by comparing the time series change of the polarization parameter (Δ, Ψ) obtained by the actual measurement with the time series change of the polarization parameter (Δ, Ψ) obtained from the Mie theoretical formula. By detecting the refractive index of the particles, it is possible to know what kind of substance the particles are made of.
【0025】具体例をもって説明すると、プラズマを利
用した処理プロセスでは粒子が成長するが、図3はこの
粒子の成長に伴う偏光パラメータの変化を示したグラフ
である。一方、多数の既知の物質について、Mieの理
論式から求めた偏光パラメータ(△,Ψ)の時系列変化
と粒子径との関係を図3と同様のグラフに作成してお
く。そして、実測によって図3に示すようなグラフが完
成したならば、既に作成してある既知の物質のグラフと
比較し、同じグラフを選び出すことで当該粒子が何から
できているかを知ることができる。Explaining with a concrete example, particles grow in the treatment process using plasma, and FIG. 3 is a graph showing the change of the polarization parameter with the growth of the particles. On the other hand, for many known substances, the relationship between the time series change of the polarization parameter (Δ, Ψ) obtained from Mie's theoretical formula and the particle diameter is created in the same graph as in FIG. Then, if the graph as shown in FIG. 3 is completed by actual measurement, it is possible to know what the particles are made of by comparing the graph of the known substance already created and selecting the same graph. .
【0026】[0026]
【発明の効果】以上に説明したように本発明によれば、
測定対象空間からの散乱光を3つの異なる偏光成分毎に
分離し、各偏光成分毎に散乱光を撮像素子に入射せし
め、各偏光成分毎の散乱光強度を求め、これら3つの散
乱光強度の値から偏光パラメータを求め、この偏光パラ
メータの時系列変化と予め理論的に求めておいた既知の
物質の偏光パラメータの時系列変化とを比較すること
で、測定対象空間の微粒子を特定するようにしたので、
当該微粒子がどの工程で混入したか、或いはどの場所で
発生したか等の重要な手がかりとなり、装置やラインの
改良の指針とすることができる。According to the present invention as described above,
The scattered light from the space to be measured is separated into three different polarized light components, the scattered light is incident on the image sensor for each polarized light component, and the scattered light intensity for each polarized light component is obtained. The polarization parameter is obtained from the value, and the time series change of this polarization parameter is compared with the time series change of the polarization parameter of the known substance that has been theoretically obtained in advance, so that the particles in the measurement target space can be specified. Because I did
It can be an important clue as to which process the fine particles were mixed in, or in which place the fine particles were generated, and can be used as a guideline for improving the apparatus or line.
【0027】また、系内の微粒子の屈折率をリアルタイ
ムで計測できるので、粒子の組成が、多層的に変化する
ような場合、その変化時期が測定できるため、コーティ
ング粒子等、超微粒子製造の工程管理や開発に有効であ
る。Further, since the refractive index of the fine particles in the system can be measured in real time, when the composition of the particles changes in multiple layers, the change time can be measured. Effective for management and development.
【0028】更に、照射光を一定の広がりを持って測定
対象空間に照射し、この測定対象空間内の所定の平面的
な領域から散乱光を偏光成分毎に撮像素子に入射せしめ
ることで、前記した効果を空間の1点ではなく、平面的
な広がりをもって測定することができる。Further, by irradiating the measuring object space with a certain spread, the scattered light is made to enter the image pickup element for each polarization component from a predetermined planar area in the measuring object space. The effect can be measured with a planar spread instead of one point in space.
【0029】特に、所定の平面的な領域から散乱光を偏
光成分毎に撮像素子に入射せしめるにあたり、偏光角が
異なる2つのレーザ光の夫々の波長を異ならせておけ
ば、偏光フィルタの代りに入射角度にそれ程敏感でない
波長選択フィルタを用いることができ、更にアパーチャ
のような高精度の位置合わせを必要とする部材を使用し
ないので、結果として高精度の測定結果を得られる。In particular, when the scattered light is made to enter the image pickup element for each polarization component from a predetermined planar area, if the wavelengths of the two laser lights having different polarization angles are made different, instead of the polarization filter. A wavelength selection filter that is not so sensitive to the incident angle can be used, and since a member that requires highly accurate alignment such as an aperture is not used, a highly accurate measurement result can be obtained.
【図1】本発明に係る微粒子測定装置の全体構成図FIG. 1 is an overall configuration diagram of a particle measuring device according to the present invention.
【図2】本発明に係る微粒子測定装置の他の例を示す全
体構成図FIG. 2 is an overall configuration diagram showing another example of a particle measuring apparatus according to the present invention.
【図3】粒子径の成長に伴う偏光パラメータの変化を示
したグラフFIG. 3 is a graph showing changes in polarization parameters with growth of particle size.
【図4】従来の微粒子測定装置の構成図FIG. 4 is a block diagram of a conventional particle measuring device.
1,31,32,33…レーザ光源、10,20,40
…受光系、11,13,21,23…アパーチャ、1
4,24…偏光フィルタ、15,26,27,45,4
6,47…波長選択フィルタ、16,28,29…光電
変換素子、25…偏光プリズム、37,38,42,4
3…誘電体ミラー、48,49,50…CCD撮像素
子、L…幅をもった照射光、S…測定対象空間。1, 31, 32, 33 ... Laser light source 10, 20, 40
... Light receiving system, 11, 13, 21, 23 ... Aperture, 1
4, 24 ... Polarizing filter, 15, 26, 27, 45, 4
6, 47 ... Wavelength selection filter, 16, 28, 29 ... Photoelectric conversion element, 25 ... Polarizing prism, 37, 38, 42, 4
3 ... Dielectric mirror, 48, 49, 50 ... CCD image pickup device, L ... Irradiation light with width, S ... Measurement target space.
Claims (8)
照射光として測定対象空間に照射し、この測定対象空間
からの散乱光を前記3つの異なる偏光成分毎に分離し、
各偏光成分毎に散乱光を光電変換素子に入射せしめ、各
偏光成分毎の散乱光強度を求め、これら3つの散乱光強
度の値から偏光パラメータを求め、この偏光パラメータ
の時系列変化と予め理論的に求めておいた既知の物質の
偏光パラメータの時系列変化とを比較することで、測定
対象空間の微粒子の測定を行うようにしたことを特徴と
する微粒子測定方法。1. A laser beam containing three different polarization components is irradiated as irradiation light onto a measurement target space, and scattered light from the measurement target space is separated for each of the three different polarization components.
The scattered light is made to enter the photoelectric conversion element for each polarization component, the scattered light intensity for each polarization component is obtained, the polarization parameter is obtained from the values of these three scattered light intensities, and the time series change of this polarization parameter and the theoretical A method for measuring fine particles, characterized in that the fine particles in the measurement target space are measured by comparing the time-series change of the polarization parameter of a known substance that has been obtained in advance.
ザ光と、偏光角度及び波長が前記第1のレーザ光と異な
る第2のレーザ光と、偏光角度及び波長が前記第1及び
第2のレーザ光と異なる第3のレーザ光とを同一方向か
ら照射光として測定対象空間に照射し、この測定対象空
間内の所定の平面的な領域から散乱光を取り出し、当該
散乱光を波長毎に分離することで散乱光を偏光成分毎の
散乱光に分離して撮像素子に入射せしめ、各偏光成分毎
の散乱光強度を求め、これら3つの散乱光強度の値から
偏光パラメータを求め、この偏光パラメータの時系列変
化と予め理論的に求めておいた既知の物質の偏光パラメ
ータの時系列変化とを比較することで、測定対象空間の
微粒子を特定するようにしたことを特徴とする微粒子測
定方法。2. A first laser beam having a polarization component of a predetermined angle, a second laser beam having a polarization angle and a wavelength different from those of the first laser beam, and a polarization angle and a wavelength having the first and second laser beams. The third laser light and the third laser light different from the above are irradiated to the measurement target space as irradiation light from the same direction, the scattered light is taken out from a predetermined planar area in the measurement target space, and the scattered light is wavelength-dependent. By separating the scattered light into scattered light for each polarization component and making it enter the image sensor, the scattered light intensity for each polarization component is obtained, and the polarization parameter is obtained from these three scattered light intensity values. A method for measuring fine particles, characterized in that fine particles in a measurement target space are specified by comparing time-series changes in parameters with time-series changes in polarization parameters of known substances that have been theoretically obtained in advance. .
測定方法において、異なる偏光成分としては観測面に対
する角度が0°,45°及び90°としたことを特徴と
する微粒子測定方法。3. The fine particle measuring method according to claim 1 or 2, wherein different polarization components have angles of 0 °, 45 ° and 90 ° with respect to the observation surface.
光源と、このレーザ光源からのレーザ光を無偏光として
測定対象空間に照射する偏光解消板と、測定対象空間か
らの散乱光を取り出すアパーチャ及びレンズ系と、これ
らアパーチャ及びレンズ系を透過した散乱光を3つの偏
光成分毎に分離する偏光素子と、分離された3つの偏光
成分の夫々が入射する第1,第2及び第3の光電変換素
子とを備えてなる微粒子測定装置。4. A laser light source that generates a laser beam of a single wavelength, a depolarizing plate that irradiates the measurement target space with the laser light from the laser light source as unpolarized light, and takes out scattered light from the measurement target space. An aperture and a lens system, a polarizing element that separates scattered light that has passed through the aperture and the lens system into three polarization components, and first, second, and third polarization components into which the three separated polarization components are incident. A fine particle measuring device comprising a photoelectric conversion element.
ザ光を生成する第1のレーザ光源と、前記第1のレーザ
光と偏光角度及び波長が異なる第2のレーザ光を生成す
る第2のレーザ光源と、前記第1及び第2のレーザ光と
偏光角度及び波長が異なる第3のレーザ光を生成する第
3のレーザ光源と、第1,第2及び第3のレーザ光を合
成して照射光として測定対象空間に照射するレンズ系
と、この測定対象空間内の所定の平面的な領域から散乱
光を取り出すレンズ系と、このレンズ系を介して取り出
した散乱光から波長を指標として三つの偏光成分に分離
する波長選択手段と、この波長選択手段で分離された各
偏光成分毎の散乱光が入射する第1,第2及び第3の撮
像素子とを備えてなる微粒子測定装置。5. A first laser light source for generating a first laser light having a polarization component of a predetermined angle, and a second laser light for generating a second laser light having a polarization angle and a wavelength different from those of the first laser light. Laser light source, a third laser light source that generates a third laser light beam having a polarization angle and a wavelength different from those of the first and second laser light beams, and the first, second, and third laser light beams are combined. The lens system that irradiates the measurement target space as irradiation light with this, the lens system that extracts scattered light from a predetermined planar area in the measurement target space, and the wavelength from the scattered light extracted through this lens system as an index A fine particle measuring apparatus comprising: a wavelength selecting means for separating into three polarized light components; and first, second and third image pickup elements on which scattered light for each polarized light component separated by the wavelength selecting means is incident.
測定装置において、前記測定対象空間からの散乱光を取
り出すレンズ系を含む受光系は、測定対象空間の一方の
側に1つ配置されていることを特徴とする微粒子測定装
置。6. The particle measuring apparatus according to claim 4 or 5, wherein one light receiving system including a lens system for taking out scattered light from the measurement target space is arranged on one side of the measurement target space. A particle measuring device characterized in that
測定装置において、前記測定対象空間からの散乱光を取
り出すレンズ系を含む受光系は、測定対象空間の左右に
それぞれ1つ配置されたことを特徴とする微粒子測定装
置。7. The particle measuring apparatus according to claim 4 or 5, wherein one light receiving system including a lens system for extracting scattered light from the measurement target space is arranged on each of the left and right sides of the measurement target space. A particle measuring device characterized by the above.
て、前記波長選択手段は誘電体ミラーであることを特徴
とする微粒子測定装置。8. The fine particle measuring device according to claim 5, wherein the wavelength selecting means is a dielectric mirror.
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JP6220629A JP3046505B2 (en) | 1994-09-14 | 1994-09-14 | Particle measuring method and particle measuring device |
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2006517297A (en) * | 2003-01-24 | 2006-07-20 | ベックマン コールター,インコーポレイティド | Extraction of polarized light scattering intensity difference for particle characterization |
EP4375641A1 (en) * | 2022-11-22 | 2024-05-29 | Wagner Group GmbH | Classification of particles using spectral analysis |
WO2024110433A1 (en) * | 2022-11-22 | 2024-05-30 | Wagner Group Gmbh | Classification of particles by means of spectral analysis |
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ES2778148T3 (en) * | 2018-01-31 | 2020-08-07 | Sick Engineering Gmbh | Analyzer for the determination of fine dust |
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1994
- 1994-09-14 JP JP6220629A patent/JP3046505B2/en not_active Expired - Fee Related
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006517297A (en) * | 2003-01-24 | 2006-07-20 | ベックマン コールター,インコーポレイティド | Extraction of polarized light scattering intensity difference for particle characterization |
EP4375641A1 (en) * | 2022-11-22 | 2024-05-29 | Wagner Group GmbH | Classification of particles using spectral analysis |
WO2024110433A1 (en) * | 2022-11-22 | 2024-05-30 | Wagner Group Gmbh | Classification of particles by means of spectral analysis |
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