JPS6231473B2 - - Google Patents
Info
- Publication number
- JPS6231473B2 JPS6231473B2 JP55187658A JP18765880A JPS6231473B2 JP S6231473 B2 JPS6231473 B2 JP S6231473B2 JP 55187658 A JP55187658 A JP 55187658A JP 18765880 A JP18765880 A JP 18765880A JP S6231473 B2 JPS6231473 B2 JP S6231473B2
- Authority
- JP
- Japan
- Prior art keywords
- image
- sample
- astigmatism
- lens
- electron
- 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
Links
- 201000009310 astigmatism Diseases 0.000 claims description 22
- 238000010894 electron beam technology Methods 0.000 claims description 15
- 230000003287 optical effect Effects 0.000 claims description 12
- 238000003384 imaging method Methods 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 3
- 238000001000 micrograph Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/02—Details
- H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement
- H01J37/153—Electron-optical or ion-optical arrangements for the correction of image defects, e.g. stigmators
Landscapes
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
Description
【発明の詳細な説明】
本発明は透過結像型の電子顕微鏡における非点
収差の補正を容易に行うための方法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for easily correcting astigmatism in a transmission imaging type electron microscope.
通常の電子顕微鏡には対物レンズに存在する光
軸に関して非対称なレンズ磁場によつて生じる非
点収差を打ち消すために、光軸に関して任意な方
位角方向に任意な強度の非対称磁場を発生させる
ことのできる非点収差補正装置（ステイグメー
タ）が組み込まれている。このステイグメータの
調整は対物レンズの非点収差による影響が大きく
現われる高倍率における螢光板上の顕微鏡像を観
察しながら行われるのが普通である。しかし乍
ら、像倍率を変えると対物レンズの非点収差の方
向や強さも変化してしまうため、一度高倍率像に
おいてステイグメータを調整した後における低倍
率像の写真撮影は、経験や勘に頼つてステイグメ
ータの状態を僅かづつズラせることによつて行つ
ていた。更に、簡易型や中型の電子顕微鏡のよう
に像倍率が数万倍程度にしか拡大されない装置に
おいては像を観察しながらステイグメータを調整
するという操作が難かしくなり正確に行われない
欠点があつた。 In order to cancel astigmatism caused by a lens magnetic field that is asymmetric with respect to the optical axis that exists in an objective lens, ordinary electron microscopes have the ability to generate an asymmetric magnetic field of arbitrary strength in an arbitrary azimuthal direction with respect to the optical axis. It has a built-in astigmatism correction device (stigmeter). This adjustment of the stigmater is normally carried out while observing a microscope image on a fluorescent plate at high magnification, where the influence of astigmatism of the objective lens is significant. However, since changing the image magnification also changes the direction and strength of the astigmatism of the objective lens, taking photographs of low-magnification images after adjusting the stigmater for high-magnification images relies on experience and intuition. This was done by slightly shifting the status of the stigma meter. Furthermore, in devices such as simple and medium-sized electron microscopes whose image magnification is only a few tens of thousands of times, it is difficult to adjust the stigmater while observing the image, making it difficult to do so accurately. .
本発明はこのような欠点を除去するためのもの
で、比較的低倍率においてもステイグメータの調
整が正確且つ容易に行われるようにすることを目
的とするものである。以下本発明を図面に基づい
て詳説する。 The present invention is intended to eliminate such drawbacks, and aims to enable accurate and easy adjustment of the stigmater even at relatively low magnifications. The present invention will be explained in detail below based on the drawings.
第１図は電子顕微鏡により試料像が結像される
状態における電子光学系を説明するための略図で
ある。図中１は電子銃を示しており、該電子銃は
微小な仮想光源（クロスオーバー・ポイント）Ｓ
から電子線が放射されるように電子線を電子顕微
鏡の光学系に入射させる。電子銃１からの電子線
は先ず第１集束レンズＣ１（図面にはそのレンズ
主面のみ示す。以下に述べる電子レンズに関して
も同じとする。）により電子銃１のクロスオーバ
ー・ポイントの像を２に示す位置に結像する。該
クロスオーバー像から発散した電子線は第２集束
レンズＣ２により光軸と略平行な状態で薄膜状試
料３を照射し、その透過平行電子線は対物レンズ
OLによつてその下方４の位置にクロスオーバー
像を結像した後、中間レンズILの物面位置５の
試料像を結像する。中間レンズILはこれらのク
ロスオーバー像と試料像を夫々位置６、７に結像
させ、投影レンズは更にクロスオーバー像を位置
８に試料像を螢光板９上に拡大結像させる。 FIG. 1 is a schematic diagram for explaining an electron optical system in a state where a sample image is formed by an electron microscope. 1 in the figure indicates an electron gun, which is a minute virtual light source (crossover point) S
The electron beam is made incident on the optical system of the electron microscope so that the electron beam is emitted from the electron beam. The electron beam from the electron gun 1 is first converted into an image at the crossover point of the electron gun 1 by the first focusing lens C1 (only the main surface of the lens is shown in the drawing. The same applies to the electron lens described below). The image is formed at the position shown in . The electron beam diverged from the crossover image is irradiated onto the thin film sample 3 by the second focusing lens C2 in a state substantially parallel to the optical axis, and the transmitted parallel electron beam is passed through the objective lens.
After a crossover image is formed at a position 4 below the OL, a sample image at an object plane position 5 of the intermediate lens IL is formed. The intermediate lens IL forms the crossover image and the sample image at positions 6 and 7, respectively, and the projection lens further forms the crossover image at position 8 and enlarges the sample image onto the fluorescent plate 9.
以上のような光学系が得られるように各電子レ
ンズの強度を調整することにより、螢光板９上に
結像される試料の顕微鏡像を肉眼で観察したり、
螢光板の下方に設けられるカメラ装置によつて写
真撮影を行うことができるが、顕微鏡像には対物
レンズの非点収差による影響が大きく現われるた
め、対物レンズOLの下方に設けられた二組の８
極子レンズ等からなるステイグメータコイル１０
の電源を調整して、非点収差を補正する操作を行
つていた。この非点収差補正の操作は螢光板９上
に結像される顕微鏡像を観察しながら行うが正観
に行うためには熟練を要し、長時間を費してい
た。 By adjusting the strength of each electron lens to obtain the optical system described above, it is possible to observe the microscopic image of the sample formed on the fluorescent plate 9 with the naked eye,
Photographs can be taken with a camera device installed below the fluorescent plate, but since the astigmatism of the objective lens is greatly affected by the microscope image, two sets of cameras installed below the objective lens OL are used. 8
Stigmeter coil 10 consisting of a polar lens etc.
I was adjusting the power supply to correct astigmatism. This astigmatism correction operation is performed while observing the microscopic image formed on the phosphor plate 9, but it requires skill and takes a long time to perform it properly.
第２図は第３図に示す装置を用いて非点収差補
正を行う場合における電子線の経路を第１図と対
比して表わしたもので、中間レンズILの強度が
変化しており、対物レンズOLにより４の位置に
結像されたクロスオーバー像が投影レンズPLの
物面位置７に結像される。その結果、螢光板９の
中央には顕微鏡像ではなく電子銃のクロスオーバ
ー像が結像されることになる。この結像状態は結
晶性試料の回折像を得る場合のものと同じであ
る。尚、蛍光板上に結像するクロスオーバー像
は、電子銃１に形成される仮想光源Ｓの形状や対
物レンズに存在する非点収差の影響を受けて必ず
しも正確な円形とはならないが、蛍光板上のクロ
スオーバ像が縮小像であるため、肉眼観察におい
ては、略円形の点像として観察される。 Figure 2 shows the path of the electron beam when astigmatism correction is performed using the apparatus shown in Figure 3, in comparison with Figure 1.The intensity of the intermediate lens IL is changing, and the objective A crossover image formed at position 4 by lens OL is formed at object plane position 7 of projection lens PL. As a result, a crossover image of the electron gun is formed at the center of the fluorescent plate 9 instead of a microscope image. This imaging state is the same as that used when obtaining a diffraction image of a crystalline sample. Note that the crossover image formed on the fluorescent screen is not necessarily an exact circle due to the shape of the virtual light source S formed in the electron gun 1 and the astigmatism present in the objective lens. Since the crossover image is a reduced image, it is observed as a substantially circular point image when observed with the naked eye.
本発明方法を実施する場合には、第３図の装置
における結像レンズ系（実施例ではILとPL）の
電源１１を調整して第１図に示す状態から第２図
に示す状態に切り換えると共に、試料３の上方に
設けられた二段の偏向コイル１２，１３に供給さ
れる信号源を連動切り換えスイツチ１４を用いて
通常の偏向電源１５から歳差偏向電源１６に切り
換える。該歳差偏向電源１６の出力信号が２段の
偏向コイル１２と１３に供給されると試料３を照
射する電子線の試料照射位置と入射角を一定に保
つたまま光軸に関する入射方位角を連続的（又は
断続的）に変化させる歳差偏向が行われる。この
とき、第４図に示すように光軸方向から眺めた螢
光板９の表面には光軸中心１７を中心とする円１
８の円周上を回転するクロスオーバー像が観察さ
れる。又歳差偏向の周期を短かくすると、肉眼に
はリング状の輝線として観察される。このリング
状輝線の形状は対物レンズに存在する非点収差の
影響を受けることになる。何故なら、上述した歳
差偏向によつて、対物レンズの磁場を通過する電
子線は、対物レンズ磁場中の光軸から等しい距離
だけ離れた箇所を通過することにより、レンズ磁
場による偏向作用を受けることになるためであ
る。例えば、対物レンズに非点収差がない場合に
は、対物レンズを通過する電子線が受ける偏向作
用が、光軸に関して対称なものとなるので、蛍光
板上に結像するクロスオーバー像の軌跡も光軸に
関して対称、即ち真円となる。これに対して、対
物レンズに非点収差が存在する場合には、対物レ
ンズを通過する電子線が受ける偏向作用が、光軸
に関して非対称なものとなり、蛍光板上に結像す
るクロスオーバー像の軌跡も光軸に関して非対
称、例えば、第４図の破線１９で示すような楕円
となる。従つて、このような歳差偏向を行いつつ
非点収差補正素子１０の電源２０を調整し、螢光
板９上に表示される輝線の形が真円となるように
すれば非点収差を正確に補正する状態に設定する
ことができる。このような非点収差補正装置の調
整操作を終えた後に、歳差偏向を停止して結像レ
ンズ系の電源１１を第１図の状態に切り換えるこ
とによつて非点収差が正確に補正された鮮明な顕
微鏡像を螢光板９上に表示させることができる。 When carrying out the method of the present invention, the power supply 11 of the imaging lens system (IL and PL in the example) in the apparatus shown in FIG. 3 is adjusted to switch from the state shown in FIG. 1 to the state shown in FIG. 2. At the same time, the signal source supplied to the two-stage deflection coils 12 and 13 provided above the sample 3 is switched from the normal deflection power supply 15 to the precession deflection power supply 16 using the interlocking changeover switch 14. When the output signal of the precessional deflection power source 16 is supplied to the two-stage deflection coils 12 and 13, the incident azimuth with respect to the optical axis of the electron beam that irradiates the sample 3 is changed while keeping the sample irradiation position and incident angle constant. A continuously (or intermittent) varying precession deflection is performed. At this time, as shown in FIG.
A crossover image rotating on the circumference of 8 is observed. Furthermore, when the period of precessional deflection is shortened, it is observed to the naked eye as a ring-shaped bright line. The shape of this ring-shaped emission line is affected by astigmatism existing in the objective lens. This is because, due to the precessional deflection described above, the electron beam passing through the magnetic field of the objective lens is deflected by the lens magnetic field by passing through a point in the objective lens magnetic field that is an equal distance away from the optical axis. This is because it will become a big deal. For example, if the objective lens has no astigmatism, the deflection effect of the electron beam passing through the objective lens will be symmetrical with respect to the optical axis, so the trajectory of the crossover image formed on the fluorescent screen will also be It is symmetrical about the axis, that is, it is a perfect circle. On the other hand, if the objective lens has astigmatism, the deflection effect on the electron beam passing through the objective lens will be asymmetrical with respect to the optical axis, resulting in the trajectory of the crossover image formed on the fluorescent screen. It is also asymmetrical with respect to the optical axis, for example, an ellipse as shown by the broken line 19 in FIG. Therefore, by adjusting the power source 20 of the astigmatism correcting element 10 while performing such precession deflection so that the shape of the bright line displayed on the fluorescent plate 9 becomes a perfect circle, astigmatism can be corrected accurately. It can be set to a state where it is corrected. After completing the adjustment operation of the astigmatism correction device, astigmatism can be accurately corrected by stopping the precessional deflection and switching the power supply 11 of the imaging lens system to the state shown in FIG. A clear microscopic image can be displayed on the fluorescent plate 9.
以上に詳説した如く、本発明によれば比較的倍
率の低い顕微鏡像であつても高倍率像の場合と同
様或るいはそれ以上に非点収差の状態をモニター
することができるので、電子顕微鏡に組み込まれ
た非点収差補正装置を正確且つ容易に調整するこ
とが可能となる。 As explained in detail above, according to the present invention, it is possible to monitor the state of astigmatism even in a comparatively low-magnification microscope image as well as in the case of a high-magnification image, or even better. It becomes possible to accurately and easily adjust the astigmatism correction device incorporated in the.
第１図は電子顕微鏡によつて顕微鏡像を観察す
る場合の電子線経路を示す略図、第２図は電子顕
微鏡によつて回折像を得る場合の略図、第３図は
本発明方法に使用される装置を示す略図、第４図
は第３図の装置の動作を説明するための略図であ
る。
１：電子銃、３：試料、９：螢光板、１０：非
点収差補正子、１２，１３：偏向コイル、１５：
偏向電源、１６：歳差偏向電源、Ｃ１，Ｃ２：集
束レンズ、OL：対物レンズ、IL：中間レンズ、
PL：投影レンズ。
FIG. 1 is a schematic diagram showing the electron beam path when observing a microscopic image with an electron microscope, FIG. FIG. 4 is a schematic diagram illustrating the operation of the device shown in FIG. 3. 1: Electron gun, 3: Sample, 9: Fluorescent plate, 10: Astigmatism corrector, 12, 13: Deflection coil, 15:
Deflection power supply, 16: Precession deflection power supply, C1, C2: Focusing lens, OL: Objective lens, IL: Intermediate lens,
PL: Projection lens.
Claims (1)
られる試料透過電子線を用いて試料の顕微鏡像を
結像するように構成された対物レンズや非点収差
補正装置等を備えた結像レンズ系を、前記電子銃
のクロスオーバー像を表示するための状態に設定
すると共に、前記結像レンズ系の光軸と試料とが
交わる位置を固定した状態で試料を照射する電子
線に対して、歳差運動を行なうような偏向を与え
ることを特徴とする電子顕微鏡における非点収差
検知方法。1. An imaging lens equipped with an objective lens, an astigmatism correction device, etc. configured to form a microscopic image of the sample using the sample-transmitting electron beam obtained when the sample is irradiated with an electron beam from an electron gun. The system is set to a state for displaying a crossover image of the electron gun, and the sample is irradiated with an electron beam while the position where the optical axis of the imaging lens system and the sample intersect is fixed. A method for detecting astigmatism in an electron microscope characterized by applying a deflection that causes precession.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18765880A JPS57111936A (en) | 1980-12-27 | 1980-12-27 | Astigmatism correcting device for electron microscope |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18765880A JPS57111936A (en) | 1980-12-27 | 1980-12-27 | Astigmatism correcting device for electron microscope |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57111936A JPS57111936A (en) | 1982-07-12 |
| JPS6231473B2 true JPS6231473B2 (en) | 1987-07-08 |
Family
ID=16209924
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18765880A Granted JPS57111936A (en) | 1980-12-27 | 1980-12-27 | Astigmatism correcting device for electron microscope |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57111936A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4011455B2 (en) * | 2002-10-24 | 2007-11-21 | 株式会社日立ハイテクノロジーズ | Sample observation method using transmission electron microscope |
| JP2008112748A (en) * | 2008-02-04 | 2008-05-15 | Hitachi Ltd | Scanning type charged particle microscope, and its astigmatism correcting method |
| EP2704177B1 (en) * | 2012-09-04 | 2014-11-26 | Fei Company | Method of investigating and correcting aberrations in a charged-particle lens system |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55121259A (en) * | 1979-03-14 | 1980-09-18 | Hitachi Ltd | Elelctron microscope |
-
1980
- 1980-12-27 JP JP18765880A patent/JPS57111936A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55121259A (en) * | 1979-03-14 | 1980-09-18 | Hitachi Ltd | Elelctron microscope |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57111936A (en) | 1982-07-12 |
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