JPH09184706A - Microscope and its focus setting method - Google Patents
Microscope and its focus setting methodInfo
- Publication number
- JPH09184706A JPH09184706A JP34408595A JP34408595A JPH09184706A JP H09184706 A JPH09184706 A JP H09184706A JP 34408595 A JP34408595 A JP 34408595A JP 34408595 A JP34408595 A JP 34408595A JP H09184706 A JPH09184706 A JP H09184706A
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- objective lens
- focus setting
- light
- focus
- incident light
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- Instruments For Measurement Of Length By Optical Means (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Mounting And Adjusting Of Optical Elements (AREA)
- Lens Barrels (AREA)
- Microscoopes, Condenser (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、顕微鏡及びその焦
点設定方法に係わり、特に顕微鏡用ガラス層厚み補正器
を用いた共焦点走査方式レーザ顕微鏡及びその焦点設定
の技術に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microscope and a focus setting method therefor, and more particularly to a confocal scanning type laser microscope using a glass layer thickness corrector for a microscope and a focus setting technique therefor.
【０００２】[0002]
【従来の技術】特開平７−１４０３９３号公報等に共焦
点走査方式レーザ顕微鏡を用いた半導体製造用マスク
（以下マスクという）の検査、及び該マスクを形成する
ガラス基板の厚さ偏差による検査精度の低下を顕微鏡用
ガラス層厚み補正器（以下単に厚み補正器という）を用
いて補正する技術が開示されている。2. Description of the Related Art Inspection of a mask for manufacturing a semiconductor (hereinafter referred to as a mask) using a confocal scanning type laser microscope in JP-A-7-140393 and the like, and inspection accuracy due to thickness deviation of a glass substrate on which the mask is formed. There is disclosed a technique for correcting the decrease in the value using a glass layer thickness corrector for a microscope (hereinafter simply referred to as a thickness corrector).
【０００３】このような厚み補正器を用いた共焦点走査
方式レーザ顕微鏡において、該厚み補正器の光透過層の
厚さ設定は、レーザマイクロメータ等の厚さ計測器を用
いてガラス基板の厚さ等を実測することによって、光透
過層とガラス基板とを合計した厚さが一定の基準厚とな
るように行われていた。また、マスクは厚さによってい
くつかの種類に分類されており、従来の光透過層の厚さ
設定はマスクの種類が変わると最初のマスクの計測を行
う前に行われ、以後同一種類のマスクについてはこの設
定のまま計測が行われる。そして、このように光透過層
とガラス基板とを合計した厚さが基準厚となる状態で、
共焦点走査方式レーザ顕微鏡の焦点がガラス基板の下端
面に合うように設定されていた。In a confocal scanning type laser microscope using such a thickness corrector, the thickness of the light transmitting layer of the thickness corrector is set by using a thickness measuring instrument such as a laser micrometer. By measuring the thickness and the like, the total thickness of the light transmitting layer and the glass substrate is set to a constant reference thickness. In addition, masks are classified into several types according to the thickness, and conventional thickness setting of the light transmission layer is performed before the first mask measurement when the mask type is changed, and thereafter, the same type of mask is set. For, the measurement is performed with this setting. Then, in the state where the total thickness of the light transmission layer and the glass substrate is the reference thickness in this way,
The focus of the confocal scanning laser microscope was set so as to match the lower end surface of the glass substrate.
【０００４】[0004]
【発明が解決しようとする課題】しかし、上記光透過層
の厚さ設定方法は、ガラス基板の厚さ等の物理的な計測
に基づくものであり光学的な厚さに基づくものではない
ため、ガラス基板の材質の変化等による設定誤差が含ま
れるという問題点があった。また、マスクの種類が変わ
ると最初のマスクの計測を行う前に１回だけ光透過層の
厚さ設定が行われるので、以後の同一種類のマスクの計
測時に温度変化等の要因によって光透過層とガラス基板
とを合計した厚さが基準厚に対して変動するため、共焦
点走査方式レーザ顕微鏡の焦点がずれるという問題があ
った。However, the above-mentioned method of setting the thickness of the light transmitting layer is based on physical measurement of the thickness of the glass substrate and not on the optical thickness. There is a problem that a setting error due to a change in the material of the glass substrate is included. Also, when the mask type changes, the thickness of the light transmission layer is set only once before the first measurement of the mask, so that the light transmission layer may be changed due to a temperature change or the like during subsequent measurement of the same type of mask. Since the total thickness of the glass substrate and the glass substrate fluctuates with respect to the reference thickness, there is a problem that the focus of the confocal scanning laser microscope is deviated.
【０００５】本発明は、上述する問題点に鑑みてなされ
たもので、以下の点を目的としている。 （１）計測対象物のガラス層の材質の違いによる計測精
度の低下を押さえることが可能な顕微鏡を提供する。 （２）計測対象物のガラス層の光学的な厚さに基づく顕
微鏡の焦点設定方法を提供する。 （３）周囲温度の変化に対して安定した顕微鏡の焦点設
定方法を提供する。The present invention has been made in view of the above-mentioned problems, and has the following objects. (1) To provide a microscope capable of suppressing a decrease in measurement accuracy due to a difference in material of a glass layer of a measurement target. (2) A focus setting method for a microscope based on the optical thickness of the glass layer of the measurement object is provided. (3) A focus setting method for a microscope that is stable against changes in ambient temperature is provided.
【０００６】[0006]
【課題を解決するための手段】上述した目的を果たすた
めに、第１の手段として、計測対象物のガラス層の厚さ
に応じて厚みが設定される光透過層を介して計測光を対
物レンズによってガラス層の下端面に集光して照射する
とともに、計測対象物からの反射光の強度を対物レンズ
を介して光検出器によって検出することにより、下端面
上に形成された対象部の寸法を計測する顕微鏡におい
て、計測対象物を挟んで前記対物レンズと同一光軸上に
対向配置されて対物レンズに対する光学的な位置関係が
予め計測されるとともに、前記下端面に焦点設定入射光
を集光して照射する焦点設定用対物レンズと、前記下端
面からの焦点設定反射光の強度を前記焦点設定用対物レ
ンズを介して検出する焦点設定用光検出器と、前記対物
レンズの焦点設定時には前記焦点設定用対物レンズに焦
点設定入射光のみを照射させ、計測時には前記対物レン
ズに入射光のみを照射させる光切換手段とを具備し、焦
点設定入射光の強度を前記光検出器及び焦点設定用光検
出器によって検出することにより光透過層の厚さが調節
されて対物レンズの焦点位置が設定されるという手段が
採用される。In order to achieve the above object, as a first means, measurement light is objectived through a light transmission layer whose thickness is set according to the thickness of the glass layer of the measurement object. A lens collects and irradiates the lower end surface of the glass layer, and the intensity of the reflected light from the measurement object is detected by a photodetector through the objective lens, so that the target part formed on the lower end surface In a microscope for measuring dimensions, the optical position relationship with respect to the objective lens is arranged in advance so as to be opposed to the objective lens on the same optical axis with a measurement object sandwiched therebetween, and focus setting incident light is applied to the lower end surface. Focus setting objective lens for focusing and irradiating, focus setting photodetector for detecting intensity of focus setting reflected light from the lower end surface through the focus setting objective lens, and focus setting of the objective lens Time And a light switching means for irradiating only the focus setting incident light to the focus setting objective lens and for irradiating only the incident light to the objective lens at the time of measurement, and adjusting the intensity of the focus setting incident light to the photodetector and the focus. A means is adopted in which the thickness of the light transmitting layer is adjusted by detecting with the setting photodetector and the focal position of the objective lens is set.
【０００７】第２の手段として、上記第１の手段におい
て、光学的な位置関係として対物レンズの焦点と焦点設
定用対物レンズの焦点とが一致したときの対物レンズと
焦点設定用対物レンズとの距離が予め計測されるという
手段が採用される。As a second means, in the first means, the objective lens and the focus setting objective lens when the focus of the objective lens and the focus setting objective lens coincide with each other as an optical positional relationship. A means of measuring the distance in advance is adopted.
【０００８】第３の手段として、上記第１または第２の
手段において、光検出器及び焦点設定用光検出器によっ
て検出される焦点設定入射光の強度が最大となるよう光
透過層の厚さが設定されるという手段が採用される。As a third means, in the first or second means, the thickness of the light transmitting layer is set so that the intensity of the focus setting incident light detected by the photo detector and the focus setting photo detector is maximized. Is adopted.
【０００９】第４の手段として、上記第１ないし第３の
何れかの手段において、入射光と焦点設定入射光とは同
一光源から供給されるという手段が採用される。As a fourth means, in any of the above-mentioned first to third means, a means is adopted in which the incident light and the focus setting incident light are supplied from the same light source.
【００１０】第５の手段として、計測対象物のガラス層
の厚さに応じて厚みが設定される光透過層を介して入射
光を対物レンズによってガラス層の下端面に集光して照
射するとともに、計測対象物からの反射光の強度を光透
過層と対物レンズを介して検出することにより、下端面
上に形成された対象部の寸法を計測する顕微鏡の焦点設
定方法において、 ａ．前記対物レンズと同一光軸上にサンプルガラスを挟
んで焦点設定用対物レンズを対向配置する行程と、 ｂ．焦点設定用対物レンズを介してサンプルガラスの下
端面に焦点設定入射光を照射して得られる焦点設定反射
光の強度を焦点設定用対物レンズを介して検出すること
により、該焦点設定用対物レンズを移動して焦点をサン
プルガラスの下端面に合わせる行程と、 ｃ．サンプルガラスを透過した焦点設定入射光の強度を
対物レンズを介して検出することにより対物レンズを移
動して焦点をサンプルガラスの下端面に合わせる行程
と、 ｄ．前記対物レンズと焦点設定用対物レンズとの間にサ
ンプルガラスに代えて計測対象物及び光透過層を装着し
て入射光を、焦点設定用対物レンズの焦点が前記ガラス
層の下端面に合うように焦点設定用対物レンズの位置を
移動する行程と、 ｅ．前記行程ｂ、ｃにおける焦点設定用対物レンズと対
物レンズとの位置関係に基づいてガラス層の下端面に焦
点が合うように対物レンズの位置を合わせる行程と、 ｆ．前記反射光の強度が最大となるように前記光透過層
の厚みを調節する行程と、を有する手段が採用される。As a fifth means, incident light is focused on the lower end surface of the glass layer by an objective lens to irradiate it through a light transmitting layer whose thickness is set according to the thickness of the glass layer of the object to be measured. At the same time, in the focus setting method of the microscope, which measures the dimension of the target portion formed on the lower end surface by detecting the intensity of the reflected light from the measurement target via the light transmission layer and the objective lens, a. A step of arranging a focus setting objective lens facing each other with a sample glass interposed therebetween on the same optical axis as the objective lens; b. By detecting the intensity of the focus setting reflected light obtained by irradiating the lower end surface of the sample glass with the focus setting incident light through the focus setting objective lens, the focus setting objective lens is detected. To move the focus to the lower end surface of the sample glass, and c. Detecting the intensity of the focus setting incident light transmitted through the sample glass through the objective lens to move the objective lens to focus on the lower end surface of the sample glass; d. An object to be measured and a light transmitting layer are mounted between the objective lens and the focus setting objective lens instead of the sample glass so that incident light is focused on the lower end surface of the glass layer. A step of moving the position of the focus setting objective lens, and e. A step of aligning the objective lens so that the lower end surface of the glass layer is focused on the basis of the positional relationship between the objective lens for focus setting and the objective lens in the steps b and c; f. A step of adjusting the thickness of the light transmitting layer so that the intensity of the reflected light is maximized.
【００１１】[0011]
【発明の実施の形態】以下、図１及び図３を参照して、
本発明に係わる顕微鏡及びその焦点設定方法の一実施形
態について説明する。DETAILED DESCRIPTION OF THE INVENTION Referring to FIGS. 1 and 3,
An embodiment of a microscope and a focus setting method thereof according to the present invention will be described.
【００１２】図１は、本実施形態における顕微鏡の光学
系の構成図である。この図において、符号１はレーザ発
振器（光源）であり、例えば波長３２５ｎｍ（ナノメー
トル）のシングルモードレーザ光を反射鏡２に向けて出
力する。反射鏡２はレーザ光を反射鏡３に向けて反射さ
せる。反射鏡３は、レーザ光を入射光としてビームスプ
リッタ４に向けて反射する。FIG. 1 is a block diagram of the optical system of the microscope in this embodiment. In this figure, reference numeral 1 is a laser oscillator (light source), which outputs a single mode laser beam having a wavelength of 325 nm (nanometer) toward the reflecting mirror 2. The reflecting mirror 2 reflects the laser light toward the reflecting mirror 3. The reflecting mirror 3 reflects the laser light as incident light toward the beam splitter 4.
【００１３】ビームスプリッタ４は、上記反射鏡３から
入射された入射光の一部を計測光学系Ａに向けて反射す
るとともに、残りのレーザ光を透過して焦点設定用光学
系Ｂに伝搬させる。ここで、ビームスプリッタ４におい
て反射されたレーザ光は入射光として計測光学系Ａに導
かれ、ビームスプリッタ４を透過したレーザ光は焦点設
定入射光として焦点設定用光学系Ｂに導かれる。The beam splitter 4 reflects a part of the incident light incident from the reflecting mirror 3 toward the measurement optical system A and transmits the remaining laser light to propagate it to the focus setting optical system B. . Here, the laser light reflected by the beam splitter 4 is guided to the measurement optical system A as incident light, and the laser light transmitted through the beam splitter 4 is guided to the focus setting optical system B as focus setting incident light.
【００１４】計測光学系Ａは、反射鏡ａ1〜ａ4、シャッ
タａ5、ビームスプリッタａ6、光検出器ａ7、集束レン
ズａ8、ピンホールａ9、１／４λ位相板ａ10、コリメー
タレンズａ11、対物レンズａ12、及び厚さ補正器ａ13か
ら構成されている。The measuring optical system A includes reflecting mirrors a1 to a4, a shutter a5, a beam splitter a6, a photodetector a7, a focusing lens a8, a pinhole a9, a 1/4 λ phase plate a10, a collimator lens a11, an objective lens a12, and And a thickness corrector a13.
【００１５】反射鏡ａ1は、上記入射光を反射鏡ａ2に向
けて反射し、該反射鏡ａ2は入射光をシャッタａ5に向け
て反射する。シャッタａ5は入射光を通過あるいは遮蔽
してビームスプリッタａ6への入射光の伝搬をＯＮ／Ｏ
ＦＦする。ビームスプリッタａ6は、入射光をを集束レ
ンズａ8に伝搬させるとともに、該集束レンズａ8に伝搬
させた入射光が以下に説明する計測対象物すなわちマス
クＸに反射して得られる反射光を反射鏡ａ3に向けて反
射する。集束レンズａ8は、入射光をピンホールａ9に設
けられた孔に向けて収束させるとともに、上記反射光を
平行光にしてビームスプリッタａ6に伝搬させる。The reflecting mirror a1 reflects the incident light toward the reflecting mirror a2, and the reflecting mirror a2 reflects the incident light toward the shutter a5. The shutter a5 passes or shields the incident light to turn on / off the propagation of the incident light to the beam splitter a6.
FF. The beam splitter a6 propagates the incident light to the focusing lens a8, and reflects the reflected light obtained by reflecting the incident light propagated to the focusing lens a8 on the measurement object, that is, the mask X described below, to the reflecting mirror a3. Reflect toward. The focusing lens a8 converges the incident light toward a hole provided in the pinhole a9, and makes the reflected light parallel light and propagates it to the beam splitter a6.
【００１６】ピンホールａ9は、小径の孔が設けられた
遮蔽板であり、入射光を回折させて１／４λ位相板ａ10
に伝搬させるとともに、反射光のうち孔に入射された反
射光のみを上記集束レンズａ8に向けて通過させる。１
／４λ位相板ａ10は、入射光の位相を１／４波長シフト
させてコリメータレンズａ11に伝搬させるとともに、反
射光を１／４波長シフトさせて上記ピンホールａ9に伝
搬させる。コリメータレンズａ11は、ピンホールａ9に
よって回折された入射光を平行光にして反射鏡ａ4に伝
搬させるとともに、反射光をピンホールａ9の孔に向け
て収束させる。The pinhole a9 is a shielding plate provided with a small diameter hole and diffracts incident light to make it a quarter-wave plate a10.
Of the reflected light and only the reflected light incident on the hole is passed toward the focusing lens a8. 1
The / 4λ phase plate a10 shifts the phase of the incident light by ¼ wavelength to propagate it to the collimator lens a11, and shifts the reflected light by ¼ wavelength to propagate it to the pinhole a9. The collimator lens a11 collimates the incident light diffracted by the pinhole a9, propagates it to the reflecting mirror a4, and converges the reflected light toward the hole of the pinhole a9.
【００１７】反射鏡ａ4は、入射光を全反射して対物レ
ンズａ12に向けて伝搬させるとともに、反射光を全反射
して上記コリメータレンズａ11に向けて伝搬させる。対
物レンズａ12は、入射光を収束させて以下に説明する光
透過層ａ14を介して計測対象物であるマスクＸに垂直に
照射するとともに、反射光を平行光にして上記反射鏡ａ
4に向けて伝搬させる。この対物レンズａ12は、光軸Ｐ1
に沿って移動可能に構成されており、その位置をサブミ
クロン・オーダーで高精度に検出する位置検出器が備え
られている。The reflecting mirror a4 totally reflects the incident light to propagate it toward the objective lens a12, and totally reflects the reflected light to propagate toward the collimator lens a11. The objective lens a12 converges the incident light and irradiates the mask X, which is an object to be measured, vertically through a light transmission layer a14 described below, and at the same time, makes the reflected light parallel light and reflects the mirror a.
Propagate toward 4. This objective lens a12 has an optical axis P1.
A position detector for detecting the position of the position of the sub-micron order with high accuracy is provided.
【００１８】厚さ補正器ａ13は、例えば特開平７−１４
０３９３号公報に開示されたものであり、以下に説明す
るガラス基板（ガラス層）Ｘ1と同一の屈折率を有する
とともにその厚さが可変可能な上記光透過層ａ14を備え
る。該光透過層ａ14は、ガラス基板Ｘ1の厚さと自らの
厚さが常に一定の基準厚Ｖとなるようにその厚さが設定
されるものである。The thickness corrector a13 is, for example, disclosed in JP-A-7-14.
It is disclosed in Japanese Patent Publication No. 0393, and has the above-mentioned light transmission layer a14 which has the same refractive index as the glass substrate (glass layer) X1 described below and whose thickness can be changed. The thickness of the light transmitting layer a14 is set so that the thickness of the glass substrate X1 and the thickness of itself are always a constant reference thickness V.
【００１９】マスクＸは、図２の側断面図に示すよう
に、一定の厚さを有するガラス基板Ｘ1の片面にエッチ
ング等によってクロムパターン（対象部）Ｘ2が形成さ
れたものであり、該クロムパターンＸ2の線幅Ｌ等が当
該顕微鏡による計測対象とされる。この線幅Ｌの計測に
当たりマスクＸは、図示するようにガラス基板Ｘ2が対
物レンズａ12側とされて図示しないマスクホルダ上に載
置される。As shown in the side sectional view of FIG. 2, the mask X is formed by forming a chromium pattern (target portion) X2 on one surface of a glass substrate X1 having a constant thickness by etching or the like. The line width L or the like of the pattern X2 is the measurement target by the microscope. In measuring the line width L, the mask X is placed on a mask holder (not shown) with the glass substrate X2 on the objective lens a12 side as shown in the figure.
【００２０】マスクＸに照射された入射光は該マスクＸ
によって反射され、反射光として厚さ光透過層ａ14及び
上述した各構成要素を経由してビームスプリッタａ6に
よって反射鏡ａ3に向けて反射され光検出器ａ7に入射さ
れる。ここで、該反射光は、１／４λ位相板ａ10を２回
通過することになるので１／２波長の位相シフトがなさ
れるのでビームスプリッタａ6において反射される。光
検出器ａ7は、例えば光電子増倍管であり、このように
して入射された反射光の強度を電気信号として検出す
る。The incident light applied to the mask X is
Is reflected by the beam splitter a6 via the thickness light transmission layer a14 and each of the above-described components as reflected light, and is reflected by the beam splitter a6 to enter the photodetector a7. Here, since the reflected light passes through the quarter-wave plate a10 twice, the reflected light undergoes a phase shift of 1/2 wavelength and is reflected by the beam splitter a6. The photodetector a7 is, for example, a photomultiplier tube, and detects the intensity of the reflected light thus entered as an electric signal.
【００２１】一方、焦点設定用光学系Ｂは、反射鏡ｂ1
〜ｂ3、シャッｂ4、ビームスプリッタｂ5、焦点設定用
光検出器ｂ6、集束レンズｂ7、ピンホールｂ8、１／４
λ位相板ｂ9、コリメータレンズｂ10、及び焦点設定用
対物レンズｂ11によって構成されている。On the other hand, the focus setting optical system B includes a reflecting mirror b1.
To b3, shatter b4, beam splitter b5, focus setting photodetector b6, focusing lens b7, pinhole b8, 1/4
It is composed of a λ phase plate b9, a collimator lens b10, and a focus setting objective lens b11.
【００２２】 上記ビームスプリッタ４から
焦点設定用光学系Ｂに向けて伝搬された焦点設定入射光
は、反射鏡ｂ1によってシャッタｂ4に向けて反射され
る。シャッタｂ4は焦点設定入射光を通過／遮蔽してビ
ームスプリッタｂ5に伝搬させる。ビームスプリッタｂ5
は、上記シャッタｂ4から入射された焦点設定入射光を
集束レンズｂ7に伝搬させるとともに、この集束レンズ
ｂ7に伝搬させ焦点設定入射光がマスクＸに反射して得
られる焦点設定反射光を反射鏡ｂ2に向けて反射する。
集束レンズｂ7は焦点設定入射光をピンホールｂ8に設け
られた孔に向けて収束させるとともに、焦点設定反射光
を平行光にして上記ビームスプリッタｂ5に伝搬させ
る。The focus setting incident light propagated from the beam splitter 4 toward the focus setting optical system B is reflected toward the shutter b4 by the reflecting mirror b1. The shutter b4 passes / blocks the focus setting incident light and propagates it to the beam splitter b5. Beam splitter b5
Reflects the focus setting reflected light obtained by propagating the focus setting incident light incident from the shutter b4 to the focusing lens b7 and propagating to the focusing lens b7 and reflecting the focus setting incident light on the mask X. Reflect toward.
The focusing lens b7 converges the focus setting incident light toward a hole provided in the pinhole b8, and also makes the focus setting reflected light parallel light and propagates it to the beam splitter b5.
【００２３】ピンホールｂ8は、例えば小径の孔が設け
られた光遮蔽板であり、焦点設定入射光を回折させて１
／４λ位相板ｂ9に通過させるとともに、焦点設定反射
光のうち孔に入射された焦点設定反射光のみを上記ビー
ムスプリッタｂ5に向けて通過させる。１／４λ位相板
ｂ9は、焦点設定入射光の位相を１／４波長シフトさせ
てコリメータレンズｂ10に伝搬させるとともに、焦点設
定反射光の位相を１／４波長シフトさせて上記ピンホー
ルb8に伝搬させる。コリメータレンズｂ10は、ピンホー
ルｂ8によって回折された焦点設定入射光を平行光にし
て反射鏡ｂ3に伝搬させるとともに、焦点設定反射光を
ピンホールｂ8の孔に向けて収束させる。The pinhole b8 is, for example, a light shielding plate provided with a small diameter hole, and diffracts the focus setting incident light to
While passing through the / 4λ phase plate b9, only the focus setting reflected light incident on the hole out of the focus setting reflected light is passed toward the beam splitter b5. The ¼λ phase plate b9 shifts the phase of the focus setting incident light by ¼ wavelength and propagates it to the collimator lens b10, and shifts the phase of the focus setting reflected light by ¼ wavelength and propagates it to the pinhole b8. Let The collimator lens b10 collimates the focus setting incident light diffracted by the pinhole b8, propagates it to the reflecting mirror b3, and converges the focus setting reflected light toward the hole of the pinhole b8.
【００２４】反射鏡ｂ3は、焦点設定入射光を全反射し
て焦点設定用対物レンズｂ11に向けて伝搬させるととも
に、焦点設定反射光を上記コリメータレンズｂ10に向け
て伝搬させる。焦点設定用対物レンズｂ11は、焦点設定
入射光を収束させてマスクＸに照射するとともに、焦点
設定反射光を平行光にして上記反射鏡ｂ3に向けて伝搬
させる。この焦点設定用対物レンズｂ11は、その光軸Ｐ
2が上述した対物レンズａ12の光軸Ｐ1と同一軸となるよ
うに位置設定されており、また以下に説明する手順によ
って対物レンズａ12との位置関係が光学的に予め計測さ
れたものである。The reflecting mirror b3 totally reflects the focus setting incident light and propagates it toward the focus setting objective lens b11, and also propagates the focus setting reflected light toward the collimator lens b10. The focus setting objective lens b11 converges the focus setting incident light and irradiates it on the mask X, and also makes the focus setting reflected light parallel light and propagates it toward the reflecting mirror b3. The focus setting objective lens b11 has an optical axis P
The position 2 is set to be the same axis as the optical axis P1 of the objective lens a12 described above, and the positional relationship with the objective lens a12 is optically measured in advance by the procedure described below.
【００２５】マスクＸに照射された焦点設定入射光は該
マスクＸによって反射され、焦点設定反射光として上述
した各構成要素を経由してビームスプリッタｂ5によっ
て反射され、さらに反射鏡ｂ2によって反射されて焦点
設定用光検出器ｂ6に入射される。焦点設定用光検出器
ｂ6は、上述した光検出器ａ7と同様の光電子増倍管であ
り、焦点設定反射光の強度を電気信号として検出する。The focus setting incident light applied to the mask X is reflected by the mask X, is reflected as a focus setting reflected light by the beam splitter b5 via the above-mentioned components, and is further reflected by the reflecting mirror b2. The light is incident on the focus setting photodetector b6. The focus setting photodetector b6 is a photomultiplier tube similar to the photodetector a7 described above, and detects the intensity of the focus setting reflected light as an electric signal.
【００２６】次に、図３を参照して、マスクＸの計測に
先立って行われる対物レンズａ12の焦点の設定方法につ
いて説明する。Next, the method of setting the focus of the objective lens a12 prior to the measurement of the mask X will be described with reference to FIG.
【００２７】まず、この図に示すように、マスクＸに代
えてサンプルガラスＺが上記マスクホルダ上に載置され
るとともに光透過層１２ａが光路から除かれる。このサ
ンプルガラスＺは、ガラス基板Ｘ1と同一材質のガラス
で形成され上記基準厚Ｖを有するものである。First, as shown in this figure, the sample glass Z is placed on the mask holder instead of the mask X, and the light transmission layer 12a is removed from the optical path. The sample glass Z is made of the same glass material as the glass substrate X1 and has the above-mentioned reference thickness V.
【００２８】この状態において、シャッタａ5が閉じら
れて焦点設定入射光のみがサンプルガラスＺに照射さ
れ、該サンプルガラスＺの下端面Ｚ1（光軸Ｐ2に沿った
位置Ｙ0）に焦点が合うように焦点設定用対物レンズｂ1
2が移動させられる。そして、このとき対物レンズｂ12
に備えられた位置検出器によって計測される焦点設定用
対物レンズｂ11の位置Ｙbが記憶される。In this state, the shutter a5 is closed and only the focus setting incident light is applied to the sample glass Z so that the lower end surface Z1 of the sample glass Z (position Y0 along the optical axis P2) is focused. Focus setting objective lens b1
2 is moved. At this time, the objective lens b12
The position Yb of the focus setting objective lens b11 measured by the position detector provided in the is stored.
【００２９】このとき、焦点設定用光検出器ｂ6で検出
される焦点設定反射光の強度が最大、すなわちピンホー
ルｂ8を通過する焦点設定反射光の光量が最大となるこ
とが検出されることにより、焦点設定用対物レンズｂ11
の焦点が下端面Ｚ1に合ったことが判断される。At this time, it is detected that the intensity of the focus setting reflected light detected by the focus setting photodetector b6 is maximum, that is, the quantity of the focus setting reflected light passing through the pinhole b8 is maximum. , Focus setting objective lens b11
It is determined that the focal point of is aligned with the lower end surface Z1.
【００３０】このように焦点設定用対物レンズｂ11の焦
点が下端面Ｚ1に合わされると、対物レンズａ12を移動
させることにより該対物レンズａ12の焦点を下端面Ｚ1
に合わせる。そして、このとき焦点設定用対物レンズｂ
11の位置Ｙaが該焦点設定用対物レンズｂ11に備えられ
た位置検出器の出力に基づいて記憶される。この場合に
は、光検出器ａ7の出力が最大すなわちピンホールａ9を
通過する光の光量が最大になったことが検出されること
により対物レンズａ12の焦点が下端面Ｚ1に合わされた
ことが判断される。When the focus setting objective lens b11 is focused on the lower end surface Z1 as described above, the objective lens a12 is moved to move the focus of the objective lens a12 to the lower end surface Z1.
Adjust to Then, at this time, the focus setting objective lens b
The position Ya of 11 is stored based on the output of the position detector provided in the focus setting objective lens b11. In this case, it is determined that the objective lens a12 is focused on the lower end surface Z1 by detecting that the output of the photodetector a7 is maximum, that is, the amount of light passing through the pinhole a9 is maximum. To be done.
【００３１】以上の手順によって、対物レンズａ12の焦
点と焦点設定用対物レンズｂ11の焦点が一致したときの
焦点設定用対物レンズｂ11の位置に対する対物レンズａ
12の位置関係、すなわち対物レンズａ12と焦点設定用対
物レンズｂ11との距離Ｒが求められた。Through the above procedure, the objective lens a with respect to the position of the focus setting objective lens b11 when the focus of the objective lens a12 and the focus setting objective lens b11 coincide with each other.
The positional relationship of 12, that is, the distance R between the objective lens a12 and the focus setting objective lens b11 was obtained.
【００３２】続いて光学系を図１の状態に戻し、マスク
Ｘについて対物レンズａ12の焦点を以下のように下端面
Ｘ3に合わせる。まず、上述したと同様にして焦点設定
用対物レンズｂ11の焦点を下端面Ｘ3に合わせる。そし
て、距離Ｒを満足する位置に対物レンズａ12を移動す
る。この場合、対物レンズａ12の位置検出器及び焦点設
定用対物レンズｂ11の位置検出器の各検出値に基づいて
高精度に対物レンズａ12の位置が設定される。以上の手
順によって、対物レンズａ12の焦点は光学的に高精度で
下端面Ｘ3に一致されたことになる。Subsequently, the optical system is returned to the state shown in FIG. 1, and the objective lens a12 of the mask X is focused on the lower end surface X3 as follows. First, in the same way as described above, the focus setting objective lens b11 is focused on the lower end surface X3. Then, the objective lens a12 is moved to a position that satisfies the distance R. In this case, the position of the objective lens a12 is set with high accuracy based on the detection values of the position detector of the objective lens a12 and the position detector of the focus setting objective lens b11. By the above procedure, the focus of the objective lens a12 is optically highly accurately aligned with the lower end surface X3.
【００３３】この状態において、シャッタｂ4が閉じら
れるとともにシャッタａ5が開けられてマスクＸに入射
光が照射され、光検出器ａ7の出力が最大となるように
厚さ補正器ａ13の光透過層ａ14の厚さが設定される。す
なわち、ガラス基板Ｘ1の厚さに厚さ補正器ａ13の厚さ
加えた厚さがサンプルガラスＺの厚さつまり基準厚Ｖと
なるように厚さ補正器ａ13の厚さが設定される。In this state, the shutter b4 is closed and the shutter a5 is opened to irradiate the mask X with incident light, and the light transmission layer a14 of the thickness corrector a13 is maximized so that the output of the photodetector a7 becomes maximum. Thickness is set. That is, the thickness of the thickness corrector a13 is set such that the thickness of the glass substrate X1 plus the thickness of the thickness corrector a13 becomes the thickness of the sample glass Z, that is, the reference thickness V.
【００３４】このように焦点調整された顕微鏡によりク
ロムパターンＸ2の線幅Ｌは以下のように計測される。
すなわち、対物レンズ１１はガラス基板Ｘ1の下端面
（クロムパターンＸ2との接合面）Ｘ3に焦点が合うよう
に光軸Ｐ1に沿って移動させられて光検出器１３によっ
て検出され反射光の強度が最大となる位置に設定され
る。この場合、クロムパターンＸ2の有無によって反射
光の強度が異なるので該強度変化に基づいて線幅Ｌが計
測される。The line width L of the chrome pattern X2 is measured by the microscope thus adjusted in focus as follows.
That is, the objective lens 11 is moved along the optical axis P1 so that the lower end surface (bonding surface with the chrome pattern X2) X3 of the glass substrate X1 is focused, and the intensity of the reflected light detected by the photodetector 13 is increased. It is set to the maximum position. In this case, since the intensity of the reflected light differs depending on the presence or absence of the chrome pattern X2, the line width L is measured based on the intensity change.
【００３５】[0035]
【発明の効果】以上説明したように、本発明によれば以
下のような効果を奏する。 （１）計測対象物を挟んで対物レンズと同一光軸上に対
向配置されて対物レンズに対する光学的な位置関係が予
め計測されるとともに、下端面に焦点設定入射光を集光
して照射する焦点設定用対物レンズと、ガラス層の底面
からの焦点設定反射光の強度を焦点設定用対物レンズを
介して検出する焦点設定用光検出器と、対物レンズの焦
点設定時には焦点設定用対物レンズに焦点設定入射光の
みを伝搬させ、計測時には対物レンズに入射光のみを伝
搬させる光切換手段とを具備するので、計測対象物のガ
ラス層の光学的な厚さに基づいて高精度に対物レンズの
焦点位置が設定される。 （２）計測対象物のガラス層の光学的な厚さに基づいて
高精度に対物レンズの焦点位置が設定されるので、計測
対象物のガラス層の材質の違いによる計測精度の低下を
押さえることができる。 （３）周囲温度の変化に対して計測対象物の計測を安定
して行うことができる。 （４）計測対象物の計測時に物理的に該計測対象物の厚
さを計測する厚さ計測器を用いる必要がない。As described above, according to the present invention, the following effects can be obtained. (1) Opposite to the objective lens on the same optical axis with the object to be measured sandwiched therebetween, the optical positional relationship with respect to the objective lens is measured in advance, and focus setting incident light is focused and irradiated on the lower end surface. The focus setting objective lens, the focus setting photodetector that detects the intensity of the focus setting reflected light from the bottom surface of the glass layer through the focus setting objective lens, and the focus setting objective lens when setting the focus of the objective lens Since the focus setting incident light is propagated and the objective lens is propagated to the objective lens at the time of measurement, the optical switching means is provided, so that the objective lens of the objective lens can be accurately measured based on the optical thickness of the glass layer of the measurement object. The focus position is set. (2) Since the focus position of the objective lens is set with high accuracy based on the optical thickness of the glass layer of the measurement target, it is possible to suppress the deterioration of the measurement accuracy due to the difference in the material of the glass layer of the measurement target. You can (3) The measurement target can be stably measured against changes in the ambient temperature. (4) It is not necessary to use a thickness measuring device that physically measures the thickness of the measurement target when measuring the measurement target.
【図１】本発明に係わる顕微鏡及びその焦点設定方法に
おいて、顕微鏡の光学系の一実施形態を示す構成図であ
る。FIG. 1 is a configuration diagram showing an embodiment of an optical system of a microscope in a microscope and a focus setting method thereof according to the present invention.
【図２】本発明に係わる顕微鏡及びその焦点設定方法に
おいて、対物レンズの焦点調整時における光学系の構成
図である。FIG. 2 is a configuration diagram of an optical system during focus adjustment of an objective lens in the microscope and the focus setting method thereof according to the present invention.
【図３】本発明に係わる顕微鏡及びその焦点設定方法に
おいて計測対象とされるマスクの構成を示す側断面図で
ある。FIG. 3 is a side sectional view showing the configuration of a mask to be measured in the microscope and the focus setting method thereof according to the present invention.
１ レーザ発振器 ２，ａ5，ｂ4 シャッタ ３，ａ1〜ａ4，ｂ1〜ｂ3 反射鏡 ４，ａ6，ｂ5 ビームスプリッタ Ａ 計測光学系 Ｂ 焦点設定用光学系 ａ7 光検出器 ａ8，ｂ7 集束レンズ ａ9，ｂ8 ピンホール ａ10，ｂ9 １／４λ位相板 ａ11，ｂ10 コリメータレンズ ａ12 対物レンズ ａ13 厚さ補正器 ａ14 光透過層 ｂ6 焦点設定用光検出器 ｂ11 焦点設定用対物レンズ Ｌ クロムパターンの線幅 Ｐ1 対物レンズの光軸 Ｐ2 焦点設定用対物レンズの光軸 Ｒ 対物レンズと焦点設定用対物レンズとの距離 Ｘ マスク Ｘ1 ガラス基板 Ｘ2 クロムパターン Ｘ3 マスクの下端面 Ｙ0 光軸に沿ったサンプルガラスの下端の位置 Ｙa 光軸に沿った対物レンズの位置 Ｙb 光軸に沿った焦点設定用対物レンズの位置 Ｚ サンプルガラス Ｚ1 サンプルガラスの下端面 1 Laser oscillator 2, a5, b4 Shutter 3, a1 to a4, b1 to b3 Reflecting mirror 4, a6, b5 Beam splitter A Measurement optical system B Focus setting optical system a7 Photodetector a8, b7 Focusing lens a9, b8 pin Hole a10, b9 1/4 lambda phase plate a11, b10 Collimator lens a12 Objective lens a13 Thickness corrector a14 Light transmission layer b6 Focus setting photodetector b11 Focus setting objective lens L Chrome pattern line width P1 Objective lens light Axis P2 Optical axis of focus setting objective lens R Distance between objective lens and focus setting objective lens X Mask X1 Glass substrate X2 Chrome pattern X3 Bottom edge of mask Y0 Bottom edge of sample glass along optical axis Ya Optical axis Position of objective lens along Yb Position of objective lens for focus setting along optical axis Z Sample glass Z1 Bottom surface of sample glass
Claims (5)
みが設定される光透過層を介して計測光を対物レンズに
よってガラス層の下端面に集光して照射するとともに、
計測対象物からの反射光の強度を対物レンズを介して光
検出器によって検出することにより、下端面上に形成さ
れた対象部の寸法を計測する顕微鏡において、 計測対象物を挟んで前記対物レンズと同一光軸上に対向
配置されて対物レンズに対する光学的な位置関係が予め
計測されるとともに、前記下端面に焦点設定入射光を集
光して照射する焦点設定用対物レンズと、 前記下端面からの焦点設定反射光の強度を前記焦点設定
用対物レンズを介して検出する焦点設定用光検出器と、 前記対物レンズの焦点設定時には前記焦点設定用対物レ
ンズに焦点設定入射光のみを照射させ、計測時には前記
対物レンズに入射光のみを照射させる光切換手段とを具
備し、 焦点設定入射光の強度を前記光検出器及び焦点設定用光
検出器によって検出することにより光透過層の厚さが調
節されて対物レンズの焦点位置が設定されることを特徴
とする顕微鏡。1. The measurement light is focused on the lower end surface of the glass layer by an objective lens and irradiated through a light transmission layer whose thickness is set according to the thickness of the glass layer of the measurement object, and
In a microscope that measures the dimensions of the target portion formed on the lower end surface by detecting the intensity of the reflected light from the measurement target through a photodetector through the objective lens, the objective lens is sandwiched by the measurement target. And a focus setting objective lens for concentrating and irradiating the focus setting incident light on the lower end surface, the optical position relationship with respect to the objective lens being preliminarily measured on the same optical axis as And a focus setting photodetector for detecting the intensity of the focus setting reflected light from the focus setting objective lens, and irradiating only the focus setting incident light to the focus setting objective lens when setting the focus of the objective lens. And a light switching means for irradiating only the incident light to the objective lens at the time of measurement, and detecting the intensity of the focus setting incident light by the photodetector and the focus setting photodetector. A microscope characterized in that the focal position of an objective lens is set by further adjusting the thickness of the light transmitting layer.
焦点と焦点設定用対物レンズの焦点とが一致したときの
対物レンズと焦点設定用対物レンズとの距離が予め計測
されることを特徴とする請求項１記載の顕微鏡。2. The optical positional relationship is characterized in that the distance between the objective lens and the focus setting objective lens when the focus of the objective lens and the focus setting objective lens coincide with each other is measured in advance. The microscope according to claim 1.
て検出される焦点設定入射光の強度が最大となるよう光
透過層の厚さが設定されることを特徴とする請求項１ま
たは２記載の顕微鏡。3. The thickness of the light transmitting layer is set so that the intensity of incident light for focus setting detected by the photodetector and the photodetector for focus setting is maximized. The microscope described.
ら供給されることを特徴とする請求項１ないし３いずれ
かの項記載の顕微鏡。4. The microscope according to claim 1, wherein the incident light and the focus setting incident light are supplied from the same light source.
みが設定される光透過層を介して入射光を対物レンズに
よってガラス層の下端面に集光して照射するとともに、
計測対象物からの反射光の強度を光透過層と対物レンズ
を介して検出することにより、下端面上に形成された対
象部の寸法を計測する顕微鏡の焦点設定方法であって、 ａ．前記対物レンズと同一光軸上にサンプルガラスを挟
んで焦点設定用対物レンズを対向配置する行程と、 ｂ．焦点設定用対物レンズを介してサンプルガラスの下
端面に焦点設定入射光を照射して得られる焦点設定反射
光の強度を焦点設定用対物レンズを介して検出すること
により、該焦点設定用対物レンズを移動して焦点をサン
プルガラスの下端面に合わせる行程と、 ｃ．サンプルガラスを透過した焦点設定入射光の強度を
対物レンズを介して検出することにより対物レンズを移
動して焦点をサンプルガラスの下端面に合わせる行程
と、 ｄ．前記対物レンズと焦点設定用対物レンズとの間にサ
ンプルガラスに代えて計測対象物及び光透過層を装着し
て入射光を、焦点設定用対物レンズの焦点が前記ガラス
層の下端面に合うように焦点設定用対物レンズの位置を
移動する行程と、 ｅ．前記行程ｂ、ｃにおける焦点設定用対物レンズと対
物レンズとの位置関係に基づいてガラス層の下端面に焦
点が合うように対物レンズの位置を合わせる行程と、 ｆ．前記反射光の強度が最大となるように前記光透過層
の厚みを調節する行程と、を有することを特徴とする顕
微鏡の焦点設定方法。5. The incident light is focused on the lower end surface of the glass layer by an objective lens and is irradiated through the light transmitting layer whose thickness is set according to the thickness of the glass layer of the measuring object,
A focus setting method for a microscope, which measures the size of a target portion formed on a lower end surface by detecting the intensity of reflected light from a measurement target via a light transmission layer and an objective lens, comprising: a. A step of arranging a focus setting objective lens facing each other with a sample glass interposed therebetween on the same optical axis as the objective lens; b. By detecting the intensity of the focus setting reflected light obtained by irradiating the lower end surface of the sample glass with the focus setting incident light through the focus setting objective lens, the focus setting objective lens is detected. To move the focus to the lower end surface of the sample glass, and c. Detecting the intensity of the focus setting incident light transmitted through the sample glass through the objective lens to move the objective lens to focus on the lower end surface of the sample glass; d. An object to be measured and a light transmitting layer are mounted between the objective lens and the focus setting objective lens instead of the sample glass so that incident light is focused on the lower end surface of the glass layer. A step of moving the position of the focus setting objective lens, and e. A step of aligning the objective lens so that the lower end surface of the glass layer is focused on the basis of the positional relationship between the objective lens for focus setting and the objective lens in the steps b and c; f. A step of adjusting the thickness of the light transmitting layer so that the intensity of the reflected light is maximized, and a focus setting method for a microscope.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34408595A JP3715013B2 (en) | 1995-12-28 | 1995-12-28 | Microscope and focus setting method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34408595A JP3715013B2 (en) | 1995-12-28 | 1995-12-28 | Microscope and focus setting method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09184706A true JPH09184706A (en) | 1997-07-15 |
| JP3715013B2 JP3715013B2 (en) | 2005-11-09 |
Family
ID=18366540
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP34408595A Expired - Fee Related JP3715013B2 (en) | 1995-12-28 | 1995-12-28 | Microscope and focus setting method thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3715013B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6734389B2 (en) | 2000-05-30 | 2004-05-11 | Igor Troitski | Method and laser system controlling breakdown process development and space structure of laser radiation for production of high quality laser-induced damage images |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4954321B2 (en) * | 2010-08-18 | 2012-06-13 | キヤノン株式会社 | microscope |
-
1995
- 1995-12-28 JP JP34408595A patent/JP3715013B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6734389B2 (en) | 2000-05-30 | 2004-05-11 | Igor Troitski | Method and laser system controlling breakdown process development and space structure of laser radiation for production of high quality laser-induced damage images |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3715013B2 (en) | 2005-11-09 |
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