JPH0668832A - Scanning electron microscope - Google Patents
Scanning electron microscopeInfo
- Publication number
- JPH0668832A JPH0668832A JP4221342A JP22134292A JPH0668832A JP H0668832 A JPH0668832 A JP H0668832A JP 4221342 A JP4221342 A JP 4221342A JP 22134292 A JP22134292 A JP 22134292A JP H0668832 A JPH0668832 A JP H0668832A
- Authority
- JP
- Japan
- Prior art keywords
- detector
- sample
- electron microscope
- scanning electron
- charge
- 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
- 238000010894 electron beam technology Methods 0.000 claims abstract description 19
- 230000003287 optical effect Effects 0.000 claims abstract description 13
- 230000005684 electric field Effects 0.000 claims description 4
- 238000001514 detection method Methods 0.000 abstract description 6
- 230000000694 effects Effects 0.000 abstract 2
- 238000010586 diagram Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 230000001133 acceleration Effects 0.000 description 2
- 230000001678 irradiating effect Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 230000005264 electron capture Effects 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 239000012811 non-conductive material Substances 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、走査電子顕微鏡に関
し、特に、対物レンズ磁場中に試料を配置するようにし
た走査電子顕微鏡に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning electron microscope, and more particularly to a scanning electron microscope adapted to dispose a sample in a magnetic field of an objective lens.
【０００２】[0002]
【従来の技術】走査電子顕微鏡では、試料に細く集束さ
れた電子ビームを照射すると共に、電子ビームの照射位
置を走査し、電子ビームの照射に基づいて試料から発生
した２次電子を検出し、検出信号を電子ビームの走査に
同期した陰極線管に供給して２次電子像を表示するよう
にしている。ところで、対物レンズの磁場中に試料を配
置する走査電子顕微鏡が存在する。図１はこのような走
査電子顕微鏡の要部を示しており、１は対物レンズであ
る。対物レンズ１の中に試料２が配置され、この試料２
に細く集束された一次電子ビームＥＢが照射される。試
料２への電子ビームＥＢの照射により試料２からは２次
電子３が発生する。この２次電子３は対物レンズ磁場に
よって拘束され、サイクロトロン運動によりスパイラル
状に進行し、対物レンズ１の上方に取り出される。対物
レンズ１の上部には電子ビーム光軸から離されて２次電
子検出器４が配置され、２次電子検出器４には２次電子
の捕獲電圧が印加されている。光軸に沿って対物レンズ
１上方に取り出された２次電子３は、検出器４の捕獲電
界によって検出器４方向に引き寄せられ、検出器４によ
って検出される。検出器４の検出信号は、図示していな
い陰極線管に供給され、陰極線管には試料の２次電子像
が表示される。2. Description of the Related Art In a scanning electron microscope, a sample is irradiated with a finely focused electron beam, the irradiation position of the electron beam is scanned, and secondary electrons generated from the sample are detected based on the irradiation of the electron beam. The detection signal is supplied to the cathode ray tube synchronized with the scanning of the electron beam to display the secondary electron image. By the way, there is a scanning electron microscope in which a sample is placed in the magnetic field of the objective lens. FIG. 1 shows a main part of such a scanning electron microscope, and 1 is an objective lens. The sample 2 is placed in the objective lens 1, and the sample 2
The primary electron beam EB which is finely focused is irradiated. By irradiating the sample 2 with the electron beam EB, secondary electrons 3 are generated from the sample 2. The secondary electrons 3 are restrained by the magnetic field of the objective lens, travel in a spiral shape by the cyclotron motion, and are taken out above the objective lens 1. A secondary electron detector 4 is arranged above the objective lens 1 away from the electron beam optical axis, and a secondary electron capture voltage is applied to the secondary electron detector 4. The secondary electrons 3 taken out above the objective lens 1 along the optical axis are attracted toward the detector 4 by the trapping electric field of the detector 4 and detected by the detector 4. The detection signal of the detector 4 is supplied to a cathode ray tube (not shown), and a secondary electron image of the sample is displayed on the cathode ray tube.
【０００３】[0003]
【発明が解決しようとする課題】ところで、試料２が絶
縁物質や半導体材料などの導電性のないものの場合、こ
の試料への照射に伴い、試料表面が正または負にチャー
ジアップする。チャージアップの程度は、一次電子ビー
ムの加速電圧，試料の材質などによって異なるが、主に
試料より発生する２次電子，反射電子の量と試料に吸収
される電荷によるバランスが崩れたときにチャージアッ
プが生じる。例えば、試料のある領域において２次電子
の放出が多すぎる場合、その領域は正にチャージアップ
し、その領域以外で発生する２次電子を試料に呼び戻し
たり、２次電子検出器に向かうことを妨げたりする。逆
に一次電子ビームＥＢが照射された領域から放出される
２次電子が少なく、試料上に残る負の電荷が急増する
と、試料は負にチャージアップする。その場合、一次電
子ビームに不正な偏向を与えたり、２次電子の軌道に影
響を与えたりする。By the way, when the sample 2 is a non-conductive material such as an insulating material or a semiconductor material, the sample surface is charged up positively or negatively with irradiation of this sample. The degree of charge-up varies depending on the acceleration voltage of the primary electron beam, the material of the sample, etc., but it is mainly charged when the balance between the amount of secondary electrons and reflected electrons generated by the sample and the charge absorbed by the sample is lost. Up occurs. For example, when the secondary electron emission is too much in a certain region of the sample, the region is positively charged up, and secondary electrons generated in other regions are recalled to the sample or directed to the secondary electron detector. It interferes. On the contrary, when the amount of secondary electrons emitted from the region irradiated with the primary electron beam EB is small and the negative charge remaining on the sample increases rapidly, the sample is charged up negatively. In that case, the primary electron beam is improperly deflected or the trajectory of the secondary electrons is affected.
【０００４】絶縁物試料や半導体試料を走査電子顕微鏡
観察する場合、一次電子ビームの加速電圧は１ｋＶ前後
の低加速電圧とされるが、この加速電圧では、２次電子
の放出量が多いのでバランスを取りやすい半面、前記し
た正にチャージアップすることが多い。このように試料
がチャージアップした場合、チャージアップの影響を受
けた２次電子がその影響をさほど受けていない２次電子
と共に検出器４に導かれて検出される。その結果、検出
信号に基づいて陰極線管に表示される２次電子像はチャ
ージアップの影響を受けた像となる。When observing an insulator sample or a semiconductor sample with a scanning electron microscope, the accelerating voltage of the primary electron beam is a low accelerating voltage of around 1 kV. However, at this accelerating voltage, a large amount of secondary electrons are emitted, so the balance is balanced. On the other hand, it is easy to take charge, but it is often charged up positively as described above. When the sample is charged up in this way, the secondary electrons affected by the charge-up are guided to the detector 4 and detected together with the secondary electrons which are not so affected. As a result, the secondary electron image displayed on the cathode ray tube based on the detection signal becomes an image affected by charge-up.
【０００５】本発明は、このような点に鑑みてなされた
もので、その目的は、導電性の良くない試料であって
も、チャージアップの影響の少ない２次電子像を観察す
ることができる走査電子顕微鏡を実現するにある。The present invention has been made in view of the above points, and an object thereof is to observe a secondary electron image with little influence of charge-up even on a sample having poor conductivity. To realize a scanning electron microscope.
【０００６】[0006]
【課題を解決するための手段】本発明に基づく走査電子
顕微鏡は、対物レンズ中の試料に電子ビームを照射し、
その結果試料より発生した２次電子を対物レンズ磁場に
よって対物レンズ上部に導き、その２次電子を対物レン
ズ上部の光軸から離されて配置された２次電子検出器の
電界によって検出器に導いて検出するように構成した走
査電子顕微鏡において、２次電子検出器に接近した光軸
上に中空円筒を配置したことを特徴としている。A scanning electron microscope according to the present invention irradiates a sample in an objective lens with an electron beam,
As a result, the secondary electrons generated from the sample are guided to the upper part of the objective lens by the magnetic field of the objective lens, and the secondary electrons are guided to the detector by the electric field of the secondary electron detector arranged away from the optical axis of the upper part of the objective lens. In the scanning electron microscope configured to detect by the above, a hollow cylinder is arranged on the optical axis close to the secondary electron detector.
【０００７】[0007]
【作用】試料から発生する２次電子は、各種のエネルギ
ーのものが含まれている。試料上でチャージアップが発
生している場合、少なくとも、比較的エネルギーの高い
２次電子は低いものと比較してチャージアップの影響を
受ける度合いが小さい。チャージアップの影響を受けて
いないということは、試料の情報（例えば表面構造）を
多く含んでいることであり、影響を受けていない２次電
子のみを元にして像を形成すれば、正確な試料の２次電
子像を観察することができる。そのため、本発明に基づ
く走査電子顕微鏡は、２次電子検出器に接近した光軸上
に中空円筒を配置し、比較的低いエネルギーの２次電子
をこの円筒にトラップして検出器に検出されることを防
止する。The secondary electrons generated from the sample contain various types of energy. When the charge-up occurs on the sample, at least the secondary electrons having relatively high energy are less affected by the charge-up as compared with those having low charge. The fact that it is not affected by charge-up means that it contains a lot of information (for example, surface structure) of the sample, and if an image is formed only from secondary electrons that are not affected, accurate The secondary electron image of the sample can be observed. Therefore, in the scanning electron microscope according to the present invention, a hollow cylinder is arranged on the optical axis close to the secondary electron detector, and secondary electrons of relatively low energy are trapped in this cylinder and detected by the detector. Prevent that.
【０００８】[0008]
【実施例】以下、図面を参照して本発明の実施例を詳細
に説明する。図２は、本発明の一実施例を示しており、
図１の従来装置と同一部分には同一番号が付されてい
る。この実施例では、対物レンズ１の上方の検出器４に
接近した電子ビーム光軸上に、中空円筒５を配置してい
る。この円筒は接地電位とされている。このような構成
において、一次電子ビームＥＢを試料２に照射した結
果、試料２から発生した２次電子３は、対物レンズ１の
磁場に拘束されてサイクトロン運動をしながらスパイラ
ル状に進行し、対物レンズ１の上方に取り出されること
は前に述べた通りである。この場合、２次電子の軌道は
磁場の強さにより変化するが、そのエネルギーが小さい
ほど小さな回転半径で上昇する。図中点線で軌道を示し
た２次電子３ａは比較的高いエネルギーを有するもの
で、大きな回転半径で上昇する。この大きな回転半径の
２次電子は電子ビームＥＢの光軸から離されて配置され
ている検出器４の捕獲電界により引き付けられ、検出器
４に入射して検出される。Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 shows an embodiment of the present invention,
The same parts as those of the conventional device shown in FIG. 1 are designated by the same reference numerals. In this embodiment, a hollow cylinder 5 is arranged above the objective lens 1 and on the optical axis of the electron beam which is close to the detector 4. This cylinder is at ground potential. In such a configuration, as a result of irradiating the sample 2 with the primary electron beam EB, the secondary electrons 3 generated from the sample 2 are constrained by the magnetic field of the objective lens 1 and progress in a spiral shape while performing a cyclotron motion, and the objective It is taken out above the lens 1 as described above. In this case, the orbit of the secondary electrons changes depending on the strength of the magnetic field, but the smaller the energy, the higher the radius of gyration. The secondary electron 3a whose orbit is shown by the dotted line in the figure has relatively high energy and rises at a large radius of gyration. The secondary electrons having a large radius of gyration are attracted by the trapping electric field of the detector 4 which is arranged apart from the optical axis of the electron beam EB, and enter the detector 4 to be detected.
【０００９】一方、細線で示したエネルギーの低い２次
電子３ｂは、小さな回転半径で上昇し、接地電位の円筒
５に入射し、検出器４への入射は妨げられる。この結
果、検出器４の検出信号は、比較的大きなエネルギーの
２次電子に基づくもの、すなわち、試料２のチャージア
ップの影響を比較的受けていない２次電子に基づくもの
となり、このような検出信号を図示していない陰極線管
に導いて表示することにより、チャージアップの比較的
影響のない走査電子顕微鏡像を観察することができる。
なお、この実施例で、試料の材質や加速電圧により試料
２上のチャージアップの状態が変化する。そのため、中
空円筒５と検出器４の相対的な距離（間隔）を調整でき
るように構成することは有効である。すなわち、その距
離を変化させれば、中空円筒５により高いエネルギーの
２次電子を入射させることができたり、逆により低いエ
ネルギーの２次電子のみを入射させることができるよう
になる。その結果、試料のチャージアップが多い場合に
は、中空円筒５と検出器４との間の距離を変化させ、よ
り高いエネルギーの２次電子が円筒５に入射するように
調整する。逆に、試料のチャージアップが少ない場合に
は、中空円筒５と検出器４との間の距離を変化させ、よ
り低いエネルギーの２次電子のみが円筒５に入射するよ
うに調整する。このようにして、試料のチャージアップ
の状況に応じて常にチャージアップの影響の少ない２次
電子のみを検出することが可能となる。On the other hand, the secondary electron 3b having a low energy, which is shown by the thin line, rises with a small radius of gyration and is incident on the cylinder 5 at the ground potential, and is prevented from entering the detector 4. As a result, the detection signal of the detector 4 is based on the secondary electrons having a relatively large energy, that is, the secondary electrons that are relatively unaffected by the charge-up of the sample 2, and such detection is performed. By guiding the signal to a cathode ray tube (not shown) for display, it is possible to observe a scanning electron microscope image that is relatively unaffected by charge-up.
In this embodiment, the charge-up state on the sample 2 changes depending on the material of the sample and the acceleration voltage. Therefore, it is effective to configure so that the relative distance (interval) between the hollow cylinder 5 and the detector 4 can be adjusted. That is, if the distance is changed, secondary electrons having high energy can be made incident on the hollow cylinder 5, or only secondary electrons having low energy can be made incident on the contrary. As a result, when the charge-up of the sample is large, the distance between the hollow cylinder 5 and the detector 4 is changed so that secondary electrons having higher energy are incident on the cylinder 5. On the contrary, when the charge-up of the sample is small, the distance between the hollow cylinder 5 and the detector 4 is changed so that only the secondary electrons of lower energy are incident on the cylinder 5. In this way, it is possible to always detect only secondary electrons that are less affected by charge-up depending on the state of charge-up of the sample.
【００１０】図３は本発明の他の実施例を示している
が、この実施例では、中空円筒５を第１の円筒５ａとそ
の外側の第２の円筒５ｂにより構成している。第１と第
２の円筒５ａ，５ｂは電気的に接触されており、第２の
円筒５ｂは第１の円筒５ａに対し、電子ビームＥＢ光軸
に沿って移動可能に構成されている。このような構成で
は、試料２のチャージアップの状況に応じて第１と第２
の円筒５ａ，５ｂが構成する円筒５の長さＬが変化させ
られる。すなわち、円筒５の長さＬを長くすれば、より
２次電子を円筒５によってトラップしやすくなり、チャ
ージアップの量が多い場合にはＬが長くされる。FIG. 3 shows another embodiment of the present invention. In this embodiment, the hollow cylinder 5 is composed of a first cylinder 5a and a second cylinder 5b outside thereof. The first and second cylinders 5a and 5b are in electrical contact with each other, and the second cylinder 5b is configured to be movable with respect to the first cylinder 5a along the optical axis of the electron beam EB. In such a configuration, the first and the second can be changed depending on the state of charge-up of the sample 2.
The length L of the cylinder 5 formed by the cylinders 5a and 5b is changed. That is, if the length L of the cylinder 5 is increased, it becomes easier for the secondary electrons to be trapped by the cylinder 5, and L is increased when the amount of charge-up is large.
【００１１】図４は本発明の他の実施例を示している。
この実施例と図２の実施例との相違点は、中空円筒５に
電源８から低い電圧が印加されていることである。電源
８は可変電源であり、試料２のチャージアップの状況に
応じて中空円筒に印加される電圧が変えられる。FIG. 4 shows another embodiment of the present invention.
The difference between this embodiment and the embodiment of FIG. 2 is that a low voltage is applied to the hollow cylinder 5 from a power supply 8. The power supply 8 is a variable power supply, and the voltage applied to the hollow cylinder can be changed according to the state of charge-up of the sample 2.
【００１２】[0012]
【発明の効果】以上説明したように、本発明に基づく走
査電子顕微鏡は、２次電子検出器に接近した光軸上に中
空円筒を配置し、試料からの比較的低いエネルギーの２
次電子をこの円筒にトラップするように構成したので、
導電性の良くない試料であっても、チャージアップの影
響の少ない２次電子像を観察することができる。As described above, in the scanning electron microscope according to the present invention, the hollow cylinder is arranged on the optical axis close to the secondary electron detector, and the 2
Since it is configured to trap the next electron in this cylinder,
Even with a sample having poor conductivity, it is possible to observe a secondary electron image with little influence of charge-up.
【図１】従来の走査電子顕微鏡の要部を示す図である。FIG. 1 is a diagram showing a main part of a conventional scanning electron microscope.
【図２】本発明の第１の実施例である走査電子顕微鏡の
要部を示す図である。FIG. 2 is a diagram showing a main part of a scanning electron microscope which is a first embodiment of the present invention.
【図３】本発明の第２の実施例である走査電子顕微鏡の
要部を示す図である。FIG. 3 is a diagram showing a main part of a scanning electron microscope which is a second embodiment of the present invention.
【図４】本発明の第３の実施例である走査電子顕微鏡の
要部を示す図である。FIG. 4 is a diagram showing a main part of a scanning electron microscope which is a third embodiment of the present invention.
１ 対物レンズ ２ 試料 ３ ２次電子 ４ ２次電子検出器 ５ 中空円筒 ８ 可変電源 1 Objective Lens 2 Sample 3 Secondary Electron 4 Secondary Electron Detector 5 Hollow Cylinder 8 Variable Power Supply
Claims (5)
し、その結果試料より発生した２次電子を対物レンズ磁
場によって対物レンズ上部に導き、その２次電子を対物
レンズ上部の光軸から離されて配置された２次電子検出
器の電界によって検出器に導いて検出するように構成し
た走査電子顕微鏡において、２次電子検出器に接近した
光軸上に中空円筒を配置したことを特徴とする走査電子
顕微鏡。1. A sample in an objective lens is irradiated with an electron beam, and as a result, secondary electrons generated from the sample are guided to the upper part of the objective lens by a magnetic field of the objective lens, and the secondary electrons are separated from the optical axis of the upper part of the objective lens. In the scanning electron microscope configured to guide the detector to the detector by the electric field of the secondary electron detector arranged so as to detect, a hollow cylinder is arranged on the optical axis close to the secondary electron detector. Scanning electron microscope.
の長さが調節できる請求項１記載の走査電子顕微鏡。2. The scanning electron microscope according to claim 1, wherein the length of the hollow cylinder in the direction along the optical axis of the electron beam is adjustable.
を変化させ得るように構成した請求項１記載の走査電子
顕微鏡。3. The scanning electron microscope according to claim 1, wherein the relative distance between the secondary electron detector and the hollow cylinder can be changed.
１記載の走査電子顕微鏡。4. The scanning electron microscope according to claim 1, wherein the hollow cylinder is held at a ground potential.
が任意に変えられる請求項１記載の走査電子顕微鏡。5. The scanning electron microscope according to claim 1, wherein a voltage is applied to the hollow cylinder and the voltage value is arbitrarily changed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22134292A JP3190922B2 (en) | 1992-08-20 | 1992-08-20 | Scanning electron microscope |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22134292A JP3190922B2 (en) | 1992-08-20 | 1992-08-20 | Scanning electron microscope |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0668832A true JPH0668832A (en) | 1994-03-11 |
| JP3190922B2 JP3190922B2 (en) | 2001-07-23 |
Family
ID=16765306
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP22134292A Expired - Fee Related JP3190922B2 (en) | 1992-08-20 | 1992-08-20 | Scanning electron microscope |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3190922B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10134754A (en) * | 1996-11-05 | 1998-05-22 | Jeol Ltd | Scanning electron microscope |
| JP2003344597A (en) * | 2002-05-27 | 2003-12-03 | Kawasaki Heavy Ind Ltd | Structure of space for accelerating electron in x-ray microscope |
| WO2005037334A1 (en) * | 2003-10-20 | 2005-04-28 | Suminoe Textile Co.,Ltd. | Deodorizing filter |
-
1992
- 1992-08-20 JP JP22134292A patent/JP3190922B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10134754A (en) * | 1996-11-05 | 1998-05-22 | Jeol Ltd | Scanning electron microscope |
| JP2003344597A (en) * | 2002-05-27 | 2003-12-03 | Kawasaki Heavy Ind Ltd | Structure of space for accelerating electron in x-ray microscope |
| WO2005037334A1 (en) * | 2003-10-20 | 2005-04-28 | Suminoe Textile Co.,Ltd. | Deodorizing filter |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3190922B2 (en) | 2001-07-23 |
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