JPS5973840A - Object lens for scan electron microscope - Google Patents
Object lens for scan electron microscopeInfo
- Publication number
- JPS5973840A JPS5973840A JP18433382A JP18433382A JPS5973840A JP S5973840 A JPS5973840 A JP S5973840A JP 18433382 A JP18433382 A JP 18433382A JP 18433382 A JP18433382 A JP 18433382A JP S5973840 A JPS5973840 A JP S5973840A
- Authority
- JP
- Japan
- Prior art keywords
- magnetic field
- magnetic pole
- lens
- magnetic
- pole
- 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.)
- Pending
Links
- 230000005284 excitation Effects 0.000 claims description 5
- 230000008878 coupling Effects 0.000 claims description 2
- 238000010168 coupling process Methods 0.000 claims description 2
- 238000005859 coupling reaction Methods 0.000 claims description 2
- 238000001514 detection method Methods 0.000 abstract description 8
- 238000010586 diagram Methods 0.000 abstract description 2
- 239000000523 sample Substances 0.000 description 19
- 230000004075 alteration Effects 0.000 description 3
- 230000005684 electric field Effects 0.000 description 3
- 238000010894 electron beam technology Methods 0.000 description 3
- 241000257465 Echinoidea Species 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 230000000452 restraining effect Effects 0.000 description 1
- 230000001360 synchronised effect Effects 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
- H01J37/10—Lenses
- H01J37/14—Lenses magnetic
- H01J37/141—Electromagnetic lenses
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
Abstract
Description
【発明の詳細な説明】
本発明は２次電子検出効率を著しく向上できる走査電子
顕微鏡用対物レンズに関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an objective lens for a scanning electron microscope that can significantly improve secondary electron detection efficiency.
走査電子顕微鏡では電子銃より発生した一電子線を対物
レンズによって試料表面上にフォーカスし、該電子線を
偏向コイルを用いて２次元的に走査することにより試料
から発生する各種信号を検出し、イの信号を前記走査と
同期した陰極線管に輝度変調信８として導入して試料面
の観察を行なっている。この様な装置において、試料（
よ通常対物レンズの下りに置かれるため該対物レンズは
一般的に非対称であり、上磁極の穴径が４０〜５０ｍｍ
に対し、下磁極の穴径は１０〜２’Ｑｍｍである。下磁
極の穴径を大きくした方がレンズの収差は小さくできる
かコ該下磁極の穴径をあまり人さ″くりると該穴Ｊ、り
下方（試料方向）に漏洩づるレンズ磁界が増大す５ため
、試料からの低エネルギー電子（２次電子）で試料表面
像を１写る揚台には前記１ｌｉｉｌ洩磁界にＪ、す２次
電子が拘束され検出効率が著しく低下する。又、ワーキ
ングディスタンス（下磁極と試料間距向（、以下ＷＤど
一称Ｊる）を短くすると、レンズ収差は減少し分解能は
向上するが、試料表面での漏−洩磁界の強度が増大づる
ので、試料表面からの２次電子は該磁界に拘束され、−
ト磁揄或いは更に上方のレンズ部材に吸収されζしまい
、やはり検出効率は低下する。In a scanning electron microscope, an electron beam generated by an electron gun is focused onto the sample surface using an objective lens, and various signals generated from the sample are detected by scanning the electron beam two-dimensionally using a deflection coil. The sample surface is observed by introducing the signal A as a brightness modulation signal 8 into a cathode ray tube synchronized with the scanning. In such a device, the sample (
The objective lens is generally asymmetrical because it is placed below the objective lens, and the hole diameter of the upper magnetic pole is 40 to 50 mm.
On the other hand, the hole diameter of the lower magnetic pole is 10 to 2'Qmm. Can lens aberration be reduced by increasing the diameter of the hole in the bottom magnetic pole? If the diameter of the hole in the bottom magnetic pole is made too small, the lens magnetic field leaking downward (toward the sample) through the hole J will increase. Therefore, on the platform where low-energy electrons (secondary electrons) from the sample form an image of the sample surface, the secondary electrons are restrained by the above-mentioned 1liil leakage magnetic field, resulting in a significant decrease in detection efficiency. (If the distance between the lower magnetic pole and the sample (hereinafter referred to as WD) is shortened, lens aberrations will decrease and resolution will improve, but the strength of the leakage magnetic field at the sample surface will increase, so The secondary electrons of are restrained by the magnetic field, −
The light is absorbed by the magnetic field or by the lens member located further above, and the detection efficiency is also reduced.
第１図は従来の走査電子顕微鏡の対物レンズの一例の断
面図、第２図は該レンズの軸上磁界分布を示しである。FIG. 1 is a cross-sectional view of an example of an objective lens of a conventional scanning electron microscope, and FIG. 2 shows the axial magnetic field distribution of the lens.
図中、１は対物レンズの下磁極、２は下磁極であり、両
磁極は−１−り３により陽気的に結合されＣいる。４は
励磁コイルであり、Ｅｌ−り内に収納され所定゛の電流
を供給することにより前記試料磁極の間隙内にレンズ（
６界を形成づるためのものである。５は試料であり、前
記下磁極の近傍−又はぞの下方に置かれ、図示しないが
既知の試料移動機構により電子線軸に対し直角な平面内
で自由に移動でき、更には（用斜や回転等が与えられる
ようになっている。６は光電子増倍管等の２次電子検出
器Ｃ′あり、試料の横方向に設′薗してあり、該検出器
には２次電子を加速覆るための高電圧が印加しである。In the figure, 1 is the lower magnetic pole of the objective lens, 2 is the lower magnetic pole, and both magnetic poles are positively coupled by -1 and 3. Reference numeral 4 denotes an excitation coil, which is housed in an Element and supplies a predetermined current to a lens (
It is for forming the 6 realms. Reference numeral 5 denotes a sample, which is placed in the vicinity of or below the lower magnetic pole, and can be freely moved in a plane perpendicular to the electron beam axis by a known sample moving mechanism (not shown), 6 is a secondary electron detector C' such as a photomultiplier tube, which is installed in the horizontal direction of the sample. A high voltage is applied for this purpose.
従って、該電圧による電界によって試料から発生した２
次電子７は矢印の如く偏向されながら加速され検出器の
シンチレータに衝突Ｊることになる。しかし乍ら、第２
図から解るようにレンズ磁界は下ｔｉＩｉ極の下方まで
かなり尾を引いており、実際に対物レンズ磁界のピーク
値が５００ガウスの場合、ＷＤ＝Ｏｍｍ（下磁極部）で
約１００ガウス、Ｗ［）＝５ｍｍで約３０力ウス、ＷＤ
＝１Ｏｎ＋０１で約１０カウスの漏洩号支界が（ｒ在し
、この磁界の拘束力が強いため前記検出器による電界の
ｉｌ＋きにも拘わらず２次電子σ片部は矢印８て示すよ
うに上方に飛翔するため、イの検出効率は低いわけであ
る。Therefore, the electric field generated by the voltage generates 2
The next electron 7 is accelerated while being deflected as shown by the arrow, and collides with the scintillator of the detector. However, the second
As can be seen from the figure, the lens magnetic field traces its tail considerably below the lower tiIi pole, and when the peak value of the objective lens magnetic field is actually 500 Gauss, WD=Omm (lower magnetic pole) is approximately 100 Gauss, W[ )=about 30 force at 5mm, WD
= 1 On + 01, there is a leakage branch field of about 10 cous (r), and the restraining force of this magnetic field is strong, so despite the electric field il+ from the detector, the secondary electron σ part is as shown by arrow 8. Because it flies upwards, its detection efficiency is low.
而しＣ１木発明は上記の欠点を解決覆ることを目的どり
る６のであり、イの構成」−の特徴は上磁極、下磁極、
両磁極を磁気的に結合Ｊる］−り及び両Ｉｎ間隙内に゛
レンズ磁場を形成するための励（君〕イルからなり、前
記下磁極の近傍又は下方に試料を配置したレンズにおい
て、前記下磁極の陽極穴から下方に漏洩づる磁界を略相
殺りるよう４イ（ｉｎをもつ磁界を発生づる空心コイル
を前記下′ｆ４１極に取付りた走査電子顕微鏡用対物レ
ンズに存する１゜第３図は本発明の一実施例の断面図で
あり、第１図と同ｊ′、Ｔ合は同一の構成部材を示して
いる０１本発明では下磁極の下側に薄い空心のコイル９
を軸対称に取付けてあり、この空心コイルにより前記下
磁極からの漏洩磁界を相殺する磁界を発生さゼている。However, the invention of the C1 tree aims to solve and overcome the above-mentioned drawbacks.
In the lens, which comprises an excitation coil for magnetically coupling the two magnetic poles and forming a lens magnetic field in the gap between the two, the sample is placed near or below the lower magnetic pole. An air-core coil that generates a magnetic field of 4 inches is attached to the lower pole to substantially cancel out the magnetic field leaking downward from the anode hole of the lower magnetic pole. Figure 3 is a cross-sectional view of one embodiment of the present invention, and the same components as in Figure 1 are indicated at j' and T.
are installed axially symmetrically, and this air-core coil generates a magnetic field that offsets the leakage magnetic field from the lower magnetic pole.
該磁界はレンズ磁界と逆向ぎに発生され第４図のａに示
づような磁界分イロを右づる３、この逆磁界のためレン
ズ磁界は第４図に実線１）で示り−如く、本来点線のよ
うな分布をな４磁弄が修ｉ「され、下磁極の下方には殆
／υどが生じなくなる。前記空心コイルは片側を下磁極
に接し−（いるの−ｃｆｌ気抵抗抵抗由空間に置いた場
合の約」−分となり、従っＣ発ｉｔ−する磁界の強度は
同一の励磁電流でも２１８になる。The magnetic field is generated in the opposite direction to the lens magnetic field, and the magnetic field is shifted to the right as shown in a in FIG. The four magnetic fluxes, which originally have a distribution like the dotted line, are modified, and almost no /υ is generated below the bottom magnetic pole.The air-core coil has one side in contact with the bottom magnetic pole, When placed in a free space, the strength of the magnetic field generated by C is approximately 218 minutes even with the same excitation current.
今、」イルの巻数を４０ターン、供給電流を１△、コイ
ルの半径をＩｃｍ、Ｉ’Ｆさを２０１ｎｌとした場合、
補正磁界の強度はＷ Ｄ ＝ １ ｍ＋Ｊ＝Ｊ近で約５
０刀ウスであり、ＷＤ＝５ｍｍイ」近では約３０ガウス
とｌより、該補正磁界の極性をレンズ磁界のそれど逆に
覆ることにＪ、すＷ Ｄ ＝ ５ ｍ１Ｍｔ近において
対物レンズからの漏洩磁界を略キャンレルＣぎることに
なる。Now, if the number of turns of the coil is 40 turns, the supply current is 1△, the radius of the coil is Icm, and the I'F is 201nl,
The strength of the correction magnetic field is approximately 5 near W D = 1 m + J = J
Since the polarity of the correction magnetic field is opposite to that of the lens magnetic field, since WD = 5 mm, the polarity of the correction magnetic field is opposite to that of the lens magnetic field. This means that the leakage magnetic field is approximately equal to Canrel C.
従って、試料から発生した２次電子は対物レンズからの
漏洩磁界に殆／υど拘束されることがなくなり、検出器
からの電界のみにより吸引されることになり、その検出
効率は砿しく向上する。Therefore, the secondary electrons generated from the sample are hardly restrained by the leakage magnetic field from the objective lens, and are attracted only by the electric field from the detector, greatly improving the detection efficiency. .
上記空心コイルによる補ｉ［（１！ｊ界（第４図ａ）は
ｕＪ変でさることか々ｆましく、従つＣコイル９の電源
（図示Ｌ！ヂ）は可変とｈっＣいる。而し゛（、任ハ、
なＷＤにり・］シ該電源を可変し試料面何升にＪ’ｉ
Ｒるス・ｊ物しンスの漏洩１４ｉ界と補正（・Ｉｉ界と
のＸか略語になるＪ、うに１行に調整づれＬＵ Ｗ Ｄ
の大小に関係なく商い２次電子の検出効率を保持りるこ
とかできる。The supplementary i [(1! .But (, Ninha,
The power supply is varied and the sample surface is
Leakage of Rurusu j object 14i field and correction (・Ii world and X or abbreviation J, sea urchin adjusted to one line LU W D
It is possible to maintain the detection efficiency of secondary electrons regardless of the size of the secondary electrons.
以」−のＪ、うに空心コイル９を設置Ｊることにより、
ＺＯいＷ Ｄで！、）２次電子を有効に捕捉づることか
ＣきるわりＣあるか、Ｗ Ｄを短くりるどス・１物レン
スの収差か減少するためより細い電子プローブを試料に
照射できるようになる。従っＣ，畠麻買ど共に高分解能
の２次電子試料像か観察できるという効果も生ずる。By installing the air-core coil 9,
ZOi W D! ,) In order to effectively capture secondary electrons, it becomes possible to irradiate the sample with a thinner electron probe because the WD is shortened and the aberration of the single-object lens is reduced. Therefore, there is an effect that high-resolution secondary electron sample images can be observed in both C and Hatake.
第１図は従来の対物レンズを承り断面図、第２図はその
軸上磁界分布を示づ図、第３図は本発明の対物レンズの
断面図、第４図はイの軸上磁界分布を示づ図である。
１：ｔｔ＋ｉ極、２：下ｆ！＆極、３：三ｊ−り、４：
励磁コイル、５：試料、６：２次電子検出器、７：２次
電子、９：空心コイル。
特許出願人
■本電子株式会社
代表右 伊藤 −人
区
区
寸Figure 1 is a sectional view of a conventional objective lens, Figure 2 is a diagram showing its axial magnetic field distribution, Figure 3 is a sectional view of the objective lens of the present invention, and Figure 4 is an axial magnetic field distribution of A. FIG. 1: tt+i pole, 2: lower f! & pole, 3: 3 j-ri, 4:
Excitation coil, 5: sample, 6: secondary electron detector, 7: secondary electron, 9: air-core coil. Patent applicant ■Representative of Hondenshi Co., Ltd. Right Ito
Claims (1)
両磁極間隙内にレンズｒｉｉ＆場を形成りるための励磁
コイルからなり、前記下磁極の近傍又は下方に試料を配
置したレンズにおいて、前記下磁極の磁極穴から下方に
漏洩する磁界を略相殺づるような値をもつ磁界を発生ず
る空心コイルを前記下磁極に取付けたことを特徴どＪる
走査電子顕微鏡用対物レンズ゛。In a lens consisting of an upper magnetic pole, a lower magnetic pole, a yoke for magnetically coupling both magnetic poles, and an excitation coil for forming a lens rii & field in the gap between the two magnetic poles, the sample is placed near or below the lower magnetic pole. An objective lens for a scanning electron microscope, characterized in that an air-core coil is attached to the lower magnetic pole to generate a magnetic field having a value that substantially cancels out a magnetic field leaking downward from the magnetic pole hole of the lower magnetic pole.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18433382A JPS5973840A (en) | 1982-10-20 | 1982-10-20 | Object lens for scan electron microscope |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18433382A JPS5973840A (en) | 1982-10-20 | 1982-10-20 | Object lens for scan electron microscope |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS5973840A true JPS5973840A (en) | 1984-04-26 |
Family
ID=16151470
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18433382A Pending JPS5973840A (en) | 1982-10-20 | 1982-10-20 | Object lens for scan electron microscope |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5973840A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5038045A (en) * | 1989-03-21 | 1991-08-06 | Cameca | Composite electromagnetic lens with variable focal distance |
| JP2008147013A (en) * | 2006-12-11 | 2008-06-26 | Hitachi High-Technologies Corp | Scanning electron microscope |
-
1982
- 1982-10-20 JP JP18433382A patent/JPS5973840A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5038045A (en) * | 1989-03-21 | 1991-08-06 | Cameca | Composite electromagnetic lens with variable focal distance |
| JP2008147013A (en) * | 2006-12-11 | 2008-06-26 | Hitachi High-Technologies Corp | Scanning electron microscope |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3081393B2 (en) | Scanning electron microscope | |
| KR850001390B1 (en) | Device for detecting secondary electron in a scanning electron microscope | |
| US4714833A (en) | Arrangement for detecting secondary and/or backscatter electrons in an electron beam apparatus | |
| US4658136A (en) | Secondary electron detecting apparatus | |
| JPH0536371A (en) | Corpuscular ray device | |
| JP3942108B2 (en) | Particle-optical device with a secondary electron detector. | |
| US3717761A (en) | Scanning electron microscope | |
| GB2092365A (en) | Electron lens with three magnetic polepieces | |
| US5045705A (en) | Charged particle beam apparatus with charge-up compensation | |
| US5780859A (en) | Electrostatic-magnetic lens arrangement | |
| GB2081501A (en) | Device for detecting secondary electrons in a scanning electron microscope | |
| US6653632B2 (en) | Scanning-type instrument utilizing charged-particle beam and method of controlling same | |
| JPH10302705A (en) | Scanning electron microscope | |
| JPS5973840A (en) | Object lens for scan electron microscope | |
| JP2002324510A (en) | Scanning electron microscope | |
| JP3432091B2 (en) | Scanning electron microscope | |
| US5185530A (en) | Electron beam instrument | |
| JP3351647B2 (en) | Scanning electron microscope | |
| US4145678A (en) | Pickup tube structure with an improved magnetic shield | |
| JP2005032588A (en) | Magnetic field objective lens for electron microscope | |
| KR910001401B1 (en) | Deflection yoke | |
| JPS6256623B2 (en) | ||
| JP2001057172A (en) | Scanning electron microscope | |
| JPS6364255A (en) | Particle beam radiating device | |
| EP0470300A1 (en) | Electron beam apparatus with a monopole magnetic lens field |