JPS5946745A - Automatic focal point aligning unit for charged particle beam device - Google Patents
Automatic focal point aligning unit for charged particle beam deviceInfo
- Publication number
- JPS5946745A JPS5946745A JP57157927A JP15792782A JPS5946745A JP S5946745 A JPS5946745 A JP S5946745A JP 57157927 A JP57157927 A JP 57157927A JP 15792782 A JP15792782 A JP 15792782A JP S5946745 A JPS5946745 A JP S5946745A
- Authority
- JP
- Japan
- Prior art keywords
- lens
- signal
- particle beam
- sample
- focusing lens
- 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
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
- H01J37/21—Means for adjusting the focus
Landscapes
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Electron Beam Exposure (AREA)
Abstract
Description
【発明の詳細な説明】
本発明は走査電子顕微鏡等の荷電粒子線装防に用いられ
る自動焦点合わせ装置の改良に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in automatic focusing devices used for charged particle beam protection in scanning electron microscopes and the like.
走査電子顕微鏡においては第１図に示？ｌにうに電子銃
１から発生Ｊる電子線２を集中レンズ３゜４にＪ、っ゛
Ｃ試石５の表面上で微小イ「断面径を形成づるように集
束し、それど同時に該電子線２を偏向二１イル６Ｘ、６
Ｙに供給されるｆ＾仁ＹＪにＪ、って試料面１−に走査
し、該走査と間開したブラウン９′；７に試オ′≧１か
ら検出器８にＪ：って検出され、増幅器９で゛増幅され
た映像信号を輝度変調信号として供給りることにＪ、っ
Ｃ試料走査像を表示している。In a scanning electron microscope, it is shown in Figure 1. The electron beam 2 generated from the electron gun 1 is focused onto the surface of the test stone 5 by a concentrating lens 3 to form a minute cross-sectional diameter, and at the same time the electron beam 2 is Deflect line 2 21 il 6x, 6
The sample surface 1- is scanned with fﾾ＾＾ﾆJ to J, which is supplied to Y, and from the sample O'≧1 at Brown 9';7, detected by the detector 8, J: is detected. By supplying the video signal amplified by the amplifier 9 as a brightness modulation signal, a scanned image of the specimen is displayed.
この試Ｎ′＋１走音像の像倍率は前記偏向コイル６Ｘ。The image magnification of this test N'+1 sonic image was the deflection coil 6X.
６ Ｙどノノウン管の偏向：１イル１０Ｘ； ＩＯＹに
水１（走査信号１−１ど垂直走査信号Ｖと供給づる走査
電源１１の出力端子と前記偏向」イル６Ｘ、６”Ｙどの
間（こ挿入されたｉｉＪ変増変器幅器１２幅度を変化さ
けることによ−〕（切り換えられる。即ち、試料面トに
お【）る電子線走査領域と該領域に相似なブラウン管画
面の面積比を変えることによって像倍率が調整される。Deflection of 6" Y-no-noun tube: 1"10X; Water 1 (scanning signal 1-1) between IOY and the output terminal of the scanning power supply 11 which supplies the vertical scanning signal V and the deflection "Ill 6X, 6" By changing the width of the inserted IIJ variable width scale 12, the area ratio of the electron beam scanning area on the sample surface and the cathode ray tube screen similar to the area can be changed. By changing the image magnification, the image magnification is adjusted.
ブラウン管画面に表示される走査像の焦点合わせは集束
レンズの特に最終段集束レンズ（対物レンズ）４の励磁
電源１３の出力を調整して試料面上にお（プる電子線の
断面径を最小になることを確認覆ることによ７） −Ｕ
＜ｊｉつれるが、この調整は試料走査像の肉眼観察に
基づくものであるため、最近この調整を自動化りるため
の自動焦点合′わけ゛装置が実用化されている。第１図
中、１／Ｉで示リブロックはこのような自動焦点、含わ
Ｕを行うための自動焦点合わせ回路Ｃ′あり、走査電源
１１からの垂直走査信号をトリガー信号どじ−Ｃ励磁電
源１３の出力を順次変化さけると共に、増幅器９の出ツ
ノをモニターした結果に４１づ′い−（励磁電源１３の
適正な出力電流を決定覆る。Focusing of the scanning image displayed on the cathode ray tube screen is done by adjusting the output of the excitation power supply 13 of the focusing lens, especially the final focusing lens (objective lens) 4, to minimize the cross-sectional diameter of the electron beam (pulled onto the sample surface). 7) -U
However, since this adjustment is based on the naked eye observation of the sample scanned image, automatic focusing devices have recently been put into practical use to automate this adjustment. In Fig. 1, the rib block indicated by 1/I has an automatic focusing circuit C' for performing such automatic focusing, including U, and uses the vertical scanning signal from the scanning power supply 11 as a trigger signal. The appropriate output current of the excitation power source 13 is determined based on the results of monitoring the output of the amplifier 9 while sequentially changing the output of the excitation power source 13.
第２図及び第３図は自動焦点合わＵ回路１ ／Ｉの原理
を説明づるためのもので、第２図（ａ）は光軸方向から
眺めた試料面上にある幅を持ったＩＭ ｉ青１５と該構
造を横切る矢印１６の方向へ図（こ示す断面形状の電ｒ
ｌ！ｉ！ １７を水平走査する様子を表わしく ｉｌ
ｉす、このＪ、うな電子線走査にＪ：って試料から検出
される侶ｊ゛）波形を示づものが第２図（ｂ ）（：’
ｄうろ０．第、′３図（Ｊｌ）は第２図（ａ ）ど同
じ試旧庄杏を異４ｉ、−，た１（ｊ１而径をイ］りる電
子線′１ε３で行うもの（゛、この走査にＪ、って得ら
れる信号波形を示しｌ、：ものが第３３図（１））であ
る。これらの図から、試１’ｉｌを走Ｉ″ＩＣＪる電子
線断面が小さい稈、信号波形の高さが高く、ピーク波形
の幅す狭い鋭い波形になることが分る。従来の自動焦５
気含ｔ〕ｉＪ装買はこ、のようイ１現象を利用りるもの
で、電ｆ“線の試利走゛白によつ−Ｃ検出される信号を
微分回路Ａゝ）フィルター回路を用いて高周波成分のみ
を取り出（）、高周波成分のビーク伯又はその梢（９飴
を電子線の断面径に対応りる信号とみなし、これらのピ
ーク値又は梢ｎ ｌ＋ｒＪが最大ど４Ｔるように対物レ
ンズの励（鮭を設定づ−るものが大部分である。Figures 2 and 3 are for explaining the principle of the automatic focusing U circuit 1/I. Figure 2 (a) shows an IM i with a certain width on the sample surface viewed from the optical axis direction. In the direction of blue 15 and arrow 16 that crosses the structure (the cross-sectional shape of the electric r
l! i! Shows how 17 is horizontally scanned.il
Figure 2(b)(:'
d Uro 0. Fig. 3 (Jl) shows the same scanning as in Fig. 2 (a) performed using an electron beam 4i, -, 1 (j1 with a diameter of The signal waveform obtained by J is shown in Figure 33 (1)).From these figures, it can be seen that the electron beam cross-section of the sample 1'il is small, and the signal waveform is It can be seen that the height of the peak waveform is high and the width of the peak waveform is narrow and sharp.
The iJ system utilizes the phenomenon shown in A1, and the signal detected by the trial run of the electric F wire is converted into a differentiator circuit A) and a filter circuit. Take out only the high frequency components using (), and consider the high frequency component Beak's ratio or its top (9) as a signal corresponding to the cross-sectional diameter of the electron beam, and calculate the peak value or top of the peak n l + rJ to be at most 4T. In most cases, the objective lens is excitation (salmon is set).
第４図＋３１え１物レンズ電流の変化に対応さけて電子
線の断面径を表わづ前記ピーク１ｎ又は積算値どうの変
換信号の変化覆る様子を示す１〕ので、このような典型
的な関係が１１１られる弱含に【、Ｌ、変換１１１号が
最大１直を示づ対物レンズ電流舶にＪ３いてｊ［シい焦
点合ねけが行なわれる。Figure 4+31 represents the cross-sectional diameter of the electron beam in response to changes in the object lens current, and shows how the converted signal changes over the peak 1n or integrated value. When the relationship 111 is weakly expressed, the conversion 111 indicates a maximum of 1 focal length, and the objective lens current is J3, and the focal point is out of focus.
ところで、走査電子顕微鏡の電子〉に学系（ごは一般に
非点収差が存右りるのＣ１この、月点収Ｘ苓抽正ηる〕
こめのｘｙ ３’、ｊ非Ｊｊ１補正駅百が相み込Ｊ：れ
でいる。この非点補正装置を正しく調”Ｊ＋ρしく：１
１貞収差の影響を取り除かないと対物レンズ電流と変換
信号どの関係は第５５図に示りＪ、うなものとなってし
まい、図中１−Ｐｌ、 Ｌ、Ｉ’）２に示す二つの対物
電流値のいずれかにｄ３いη変換信号の最大ｌｉｌ′ｔ
／＋’：牛り゛ることになる。しかしながら、このＩ
＋）１．１１）２のいずれかに設定しても正しい焦点は
１１ノられず、従来の自動焦点合わＵ゛装四ｄ’５いて
（ま市しい非点収差補正が行われてい４１いと＋Ｉ−Ｌ
／ ＜ ｔｉｔ！能し／、ｆい傷合がしばしばあった。By the way, in the electron field of a scanning electron microscope, there is generally astigmatism.
Kome's xy 3', j non-Jj1 correction station 100 is combined J: Redeira. Adjust this astigmatism correction device correctly: 1
If the influence of 1-Pl, L, I') 2 is not removed, the relationship between the objective lens current and the converted signal will be as shown in Fig. 55. The maximum lil′t of the η conversion signal that is d3 in any of the current values
/+': The cow will be destroyed. However, this I
+) 1. Even if you set it to 11) or 2, the correct focus cannot be obtained, and the conventional automatic focusing system (U4D'5) (unprecedented astigmatism correction is performed) +IL
/ <tit! There were often serious injuries.
本発明は非点収差補正が正（イ「に補１１され（いない
状態においても、正しい焦点合、Ｐ） Ｌ！をｉＪうこ
と、更には対物レンズ以外にステイグメータを（Ｊ４＞
めた厳密な意味での焦点合４つＩ！を自動的に１１つこ
とをＩ］的とづるちのＣ゛、前電粒子線汎；から発生す
る粒子線を東栄レンズにより試わ１面一１ｃ微小なビー
ム径が形成されるように照射し、偏向手段によっ（試オ
″１１面」−の一定領域を走査し、該走査と同期して前
記集束レンズのレンズ強度を変化ざＵると共に試料から
１５）られる映像信号より前記粒子線の試料面上にお（
）るじ−ム径に対応覆る変換信号を検出し、該変換信号
の最大値よりも所定量イ］（い値の変換信号に対応する
二つのレンズ強度（１，−１，１−の饋に設定づること
を特徴どづる（）の（゛ある。The present invention has a positive astigmatism correction (A11 (correct focusing even when not present, P) L!, and a stigma meter (J4>) in addition to the objective lens.
Focusing in the strict sense of the word I! The particle beam generated from the target and the previous electric particle beam was irradiated with a Toei lens so that a beam diameter of 1 cm was formed on each surface. , a certain area (11 planes) is scanned by the deflection means, and in synchronization with the scanning, the lens strength of the focusing lens is changed, and the image signal from the sample is used to detect the particle beam. On the sample surface (
) Detects a conversion signal that corresponds to the lens diameter, and detects a conversion signal that corresponds to the maximum value of the conversion signal, and detects the two lens intensities (1, -1, 1- The feature is to set it to () of (゛).
以下、本発明の１６１理と実施例・技Ｆｌを図面に基づ
いＣ１説りる。Hereinafter, 161 principles and embodiments/techniques of the present invention will be explained based on the drawings.
非点収Ｊイの１要＜Ｅ原因は第６図に小り如く電工レン
ズの焦１ｊ：（距ｌｉ１．Ｉｔが直交する方向ｖ′−′
Ｉｉ／、１イ）たメチある。同図に（１３いで、×、ｙ
軸の交」ｊ３【にレンズ主面が通っているどηるとＸ方
向の焦点面に焦線Ｃが又ｙ方向の焦点面に焦線１三が人
々形成され、Ｃ２［の中間に最小！ｊ１乱円１）が形成
される。このＤ点が非点収差が補ｊｌされたどきの焦点
位置に相当する。Ｃ［の間隔はいわゆる非点隔〉イへ「
である。The cause of astigmatism J<E is shown in Fig. 6. The focus of the electrician's lens 1j: (the direction v'-' where the distance li1.It is orthogonal)
Ii/, 1a) There is so much. In the same figure (at 13, x, y
When the main surface of the lens passes through the intersection of the axes, j3, a focal line C is formed on the focal plane in the ! j1 random circle 1) is formed. This point D corresponds to the focal position after astigmatism has been compensated for. The interval of C is the so-called astigmatic interval.
It is.
いま、第７図（ａ ）に示り−ように、ｘ軸と角度αを
なリベク１ヘルΔ１：で表されるレンズ非点収差を４極
２対型の電磁非点補正装置（いわゆる×ｙ型′Ｊｌ魚補
正装置）ににつて補ＩＦづることを考える。図中ＳＸは
○印で示される×輔及びｙＩＩｌｌ上に位置する４極レ
ンズにｊ：つて牛ヂる非魚補ｉ［ベタ１〜ルを表し、Ｓ
ｙはＸ軸及びｙ軸と４５°回転さＵた・二！（・示され
る位置に設【〕られた他の／ｌ ０ルンス゛にＪ、って
生ずる非点補正ベタ１〜ルを表１．．こＪで、これらの
ベタ１〜ル関係の考察を容易にでするため各ベクトルが
Ｘ軸となす角度を全て２倍にして第７図（１））に示り
如く Δ［−１Ｓ×、Ｓｙとりる、。Now, as shown in Fig. 7(a), the lens astigmatism expressed by the angle α with respect to the x-axis is Δ1. Consider using a supplementary IF for a y-type 'Jl fish correction device). In the figure, SX is a quadrupole lens located on x and yIIll indicated by ○.
y is rotated 45 degrees with the X and y axes! (Table 1 shows the astigmatism correction patterns 1 to 1 caused by J to the other /l 0 lances set at the indicated position.) This table makes it easy to consider the relationship between these patterns. In order to achieve this, all angles that each vector makes with the X axis are doubled, and Δ[-1S×, Sy is obtained, as shown in FIG. 7 (1)).
第７図（１））においてΔＦはΔ）二×とΔ「ｙとの×
ｙ軸方向へり］ヘルに分割され、△「は次式６表される
。In Fig. 7(1)), ΔF is Δ)2× and Δ“y××
edge in the y-axis direction], and Δ' is expressed by the following equation 6.
ＡＦ ＝Ｊ醪Ｔ弓
又、最小１（１乱円の直径δは非点隔差△１−に比例し
、５；ｋ・ΔＦ −−〜−−・−一−・−−−−（１）
どなる。こ（ニーて゛、Ｋは電子線の試料に対する聞き
角αに関りる係数である。AF = J Moromi T Yumata, minimum 1 (the diameter δ of one random circle is proportional to the astigmatism difference △1-, 5; k・ΔF −−〜−−・−1−・−−−−(1)
bawl. Here, K is a coefficient related to the hearing angle α of the electron beam with respect to the sample.
第７図（Ｃ）中△［′は非点補正装置を動作さけたと２
′！の合成、ｉ１１点ベクトルを示し、△「′に対応り
るＪ［点隔差へＦ−’４ま次式で表される。△[' in Fig. 7(C) indicates 2 when the astigmatism correction device is avoided.
′! , the i11 point vector is expressed by the following equation:
ΔＬ′・Ｆ肩；Ｎ百−叡−・・−・−（すしたがり−Ｕ
（１）式からこのときの最小錯乱円の１径は次のよう
（ごなる。ΔL'・F shoulder;
From equation (1), the radius of the circle of least confusion in this case is as follows.
ｃ’＝ｙＪ７ヱ罷野−Ｊ母ヱー・−−・・（３）：Ｊ
ν
ｊス−１から、最小１１１乱円の状態で非点収Ｚ補１１
−装四の２絹の／Ｉ局レンズを夫々独１°ｆに走査しδ
′が順次最小ｈｉｔ ｌごイ「ろまうに制御りれば△ｌ
”）０即ちδ′ ンＯに／ｊしｉｑ、非点収差不完全に
浦１１（・さることがう）る、。c'=yJ7 Ekaino-J mother---(3):J
From ν j s−1, astigmatism Z compensation 11 in the state of minimum 111 random circles
-Scan the two silk/I station lenses of the four parts at 1°f, respectively, and δ
′ is the minimum hit in order.
``) 0, that is, δ', and the astigmatism is incomplete.
所で゛、第０レロＪお【ノる対物電流１＋１ｉ ＋−１
）ｌ 、 １． Ｐ２は夫ノＺ盲′１６図【に、１ハノ
る焦線Ｃ，ｌ−にス・１応しくおり、ｉＩジノい焦点合
４つμ即ら最小１１１乱円１）が形成されるようにりる
ためには対物１ノンズ電流の値をＬ１ヤし２
λ に設定りれぽＪ、いが、この最適値の求め方を第
８図に承り本発明の実施例装置に阜づいて説明する。By the way, the 0th rero J o [objective current 1+1i +-1
)l, 1. P2 corresponds to the focal line C, l-, which corresponds to the focal line C, l-, so that a minimum of 111 random circles 1) are formed. In order to achieve this, the value of the objective current 1 is set to L1 and 2 λ, but the method for determining this optimum value is shown in FIG. 8 and based on the apparatus according to the embodiment of the present invention. explain.
第８図中第１図と同一７１号を付したものは同一構成要
素を表わしている。第８図の装面には２対の４極レンズ
１５ｘ、１５ｙ及びイれらへ励磁電流を供給する非点補
正電源゛１Ｇからなる×ｙ型非点補正装置が絹み込まれ
てＪ３す、各４４ｆｉレンズへの電流値は電流制御回路
１７の出力によって調整される。又、対物レンズの励磁
電源１３も電流制御回路１８の出力によって調整される
。これらの電流制御回路１７．１８はスデッゾぎり変則
路１９の出力によっ−Ｃｆｌｉ制御される。試料５から
発生りる２次電子等の（、′；号は検出器８により映像
イハ弓どしＣ検出された後増幅器９を介して自８に］１
度二１ン１−ラス１〜調整回路２０に供給され、該回路
におい（映像信号の信号レベルが所定の藺に又映像信号
の：１ン１〜ンス１〜が所定範囲に収；ＬるＪ、うに自
動調整さける。自動輝度コン１〜ラスト調整回路２ｏの
出力の一部はブラ「クン管７の輝度変調信′：Ｊどしく
用いられると同時に前記スデッｆ可変回路′１９にらＩ
（給される。スデップ可変回路゛１９は入力２Ｓれた１
１９４像化５−）に早づいＣその高周波成分の強度信号
に対応りる電子線ｔｔＪｉ面径を表づ変換信号を発生し
、該変換イトラが最大１１ｒ１と４【るＪ：うにぞの出
力制御信号をステップ状に増減さｌる。中央制御回路２
１は垂直ルＰｉ Ｉｔ”ｉ号をタイミング信）シどして
２つの電流調整回路１７，１ε３．ステップ角変回路１
９及びスイッチＳｉ’、Ｓ２．３３に制御信号を供給り
る。In FIG. 8, the same reference numeral 71 as in FIG. 1 represents the same component. In the mounting shown in Fig. 8, an xy-type astigmatism correction device consisting of two pairs of quadrupole lenses 15x and 15y and a 1G astigmatism correction power supply that supplies an excitation current to them is incorporated into the J3. , the current value to each 44fi lens is adjusted by the output of the current control circuit 17. Further, the excitation power source 13 for the objective lens is also adjusted by the output of the current control circuit 18. These current control circuits 17 and 18 are controlled by the output of the Sudezogiri irregular path 19. Secondary electrons, etc. generated from the sample 5 are detected by the detector 8 and sent to the camera 8 via the amplifier 9.
The signal level of the video signal is within a predetermined range, and the signal level of the video signal is within a predetermined range. A part of the output of the automatic brightness controller 1 to the last adjustment circuit 2o is used as a brightness modulation signal of the brightness tube 7.
(Supplied. The step variable circuit 19 receives input 2S and 1
Immediately after 194 imaging 5-), a conversion signal representing the surface diameter of the electron beam ttJi corresponding to the intensity signal of the high frequency component is generated, and the conversion signal is at maximum 11r1 and 4[J: sea urchin output. The control signal is increased or decreased in steps. Central control circuit 2
1 is a vertical loop (Pi It"i) as a timing signal) and then two current adjustment circuits 17, 1ε 3. Step angle changing circuit 1
9 and switches Si', S2.33.
今、仮に非点補正装置を使用Ｕず対物レンズ電流ど変換
化６の関係が非点収差の影響で第０図に示１ような波形
で表されるものとづる。この場合に第８図の装置にｉ１
５ ＬＪる自動焦点合わせ装置を作動さｌるど、先ず中
央制御回路２１がスイッチＳ１、Ｓ２をＡンの状態どし
、電流調整回路１７の出力によって４１モレンズ１５ｘ
、１５ｙへの励磁電流を零に設定りる。次にスイッチ５
う３が端子ａ側にＩＪＪり換えられてステップ可変回路
・１９の出力が電流調整回路１８へ供給され、ス・１物
１ノンズ電流が第１０図に示１如く低い電流レベルｈ目
うステップ状に順次増加りる。このスデッノ用変の時間
幅ｔ（，１垂直走査の周期と一致しく（１３す、電流の
変化幅Δ１１．Δ■２は調整段階に応じＣ切り白λられ
るが初めの段階では大きい可変幅に設定される。Now, suppose that the relationship between the objective lens current and the conversion 6 is expressed by a waveform as shown in FIG. 1 due to the influence of astigmatism without using the astigmatism correction device. In this case, the device shown in FIG.
5 When the automatic focusing device is activated, the central control circuit 21 first sets the switches S1 and S2 to the A state, and the output of the current adjustment circuit 17 causes the 41mm lens 15x to be adjusted.
, 15y is set to zero. Next switch 5
3 is switched to the terminal a side, and the output of the step variable circuit 19 is supplied to the current adjustment circuit 18, and the step 1 current is set to a low current level h as shown in FIG. 10. It will increase sequentially. The time width t(, 1) of this Sdenno change corresponds to the period of vertical scanning (13), and the current change width Δ11. Set.
第１０図の場合には対物１ノンズ電流の１１「ｉが初め
の低い値から大ぎな変化幅Δ■１で増加し、変（β信号
が予め定められたＬレベルを越えるとルベルに電流値を
設定し、新たに小さな変化幅△Ｉ２で電流を増加さＵつ
つ常に１９られた変操信号の最大値を求めそれよりも２
０％減の値Ｓを５１怖しく記憶し、値Ｓど等しい変換信
号が１９られるまで電流のスーアップ増加を行う（第９
図には変換信号が実際の最大値Ｐに達した後のＰどＳの
１直が示されている。〉このようにしてレベルＳに対応
りるレンズ電流Ｌ ２に達Ｊると、ステップ可変回路′
１９ｔまレンズ電流１．、２ （又は−ぞれに対応Ｊる
信号）を記憶覆ると同時に、再びレンズ電流をｌ ｓに
戻してＳの変換（ｉ号が得られるまで微小スｊ−ツゾ幅
の電流増加を行ないレンズ電流（１（又はぞれにヌ・１
応する信号）の値を求める。次にスｉ゛ツゾｉｉＪ変回
路１−１ ＋Ｌ乙 Ｌｌ−）Ｌ２１９は
一丁一の値を演算し、 ２ の出力゛電流が得られ
るような制御信号を電流÷１１Ｊ整回路１８へ供給りる
１、従っ°η第８図の装置ｊ’？に、１３い−４は非点
収差が存白りる状態であってｂ最小錯乱円の状態に電ｆ
−線を集束さＵることがぐさるのＣ・、従来Ｊ、すｂ信
頼度の高い自動焦点合わＵを行うことができる。In the case of Fig. 10, the objective 1 nons current 11'i increases from the initial low value with a large change width Δ■1, and changes (when the β signal exceeds the predetermined L level, the current value changes to level 1). is set, and while increasing the current with a new small change width △I2, find the maximum value of the variable signal that is always 19, and set it by 2.
The value S of 0% reduction is memorized 51 times, and the current is increased rapidly until a conversion signal equal to the value S is 19 times (9th step).
The figure shows one shift of P to S after the conversion signal reaches its actual maximum value P. 〉In this way, when the lens current L2 corresponding to the level S is reached, the step variable circuit'
19t Lens current 1. , 2 (or the corresponding J signal), at the same time, return the lens current to l s again and convert S (increase the current by a minute width until i is obtained). Lens current (1 (or 1 for each)
find the value of the corresponding signal). Next, the switch L219 calculates each value and supplies the control signal to the current ÷ 11J adjustment circuit 18 so that the output current of 2 is obtained. R1, follow °η the device j' in Figure 8? 13-4 is a state in which astigmatism is evident, and the electric field f is in the state of the circle of least confusion b.
- It is possible to perform automatic focusing with high reliability when focusing the beam.
以にのように１ノで第ε３図の装置−にお（）る一応の
焦点合わｌが完了づると、中央制御回路２１はスインＳ
３を１）側端子へ、又スイッチＳ１をＡン状態どしＵ
／ｌ極レンズ１５ｘへの最適励磁電流強度を求める動作
を開始さ１！る。／Ｉ極レンズ１５×又Ｇ；Ｌ １５
ｙへのＩｊｌＩＩｉｉ＆電流を連続的に可変させた場合
の変換伏目変化は第４図に類似の波形を承りので、ステ
ップｉｉＪ変回路１０は４極レンズ１５×への励磁電流
をＩＦ； ＩＬＬ ｔｌ＋’＋ ／Ｊ曹ら順次ス′ｊツ
ブ状に微小幅で増加さけ、８スフ−ツブにおいて検出さ
れる変換信号が最大（「１承り励磁用流値の値（又はこ
・れに対応する信号）を検出１ノ、この値を記憶１ノて
ｌ〜１ノンズ１５×への励磁電流をこの顧に固定りる１
１次に中火制御回路１９からの制御信号がスイッチ＄２
をＡン状（７１にし−Ｕ ／ｌ ｉｉｊレンズ１６ｙｌ
Ｎの励磁電流を４極レンズ１５×の場合と同様にして順
次スアーツブ状に増加させて変換化ｆＪが最大値を示Ｊ
励磁電流を検出して、その値を保持り−る。As described above, when the focusing l in the apparatus shown in Fig. ε3 is completed in step 1, the central control circuit 21 switches the
3 to the 1) side terminal, and switch S1 to A state.
/Start the operation to find the optimum excitation current intensity for the l-pole lens 15x1! Ru. /I pole lens 15 x G; L 15
When the IjlIIIi & current to y is continuously varied, the transformation change has a waveform similar to that shown in FIG. +/J Cao et al. sequentially increase in a small width in the shape of a block, and the conversion signal detected at the 8 block is the maximum Detect 1, memorize this value, and fix the excitation current to 1~1 nons 15x at this point.
Firstly, the control signal from the medium heat control circuit 19 is sent to switch $2.
to A shape (71-U/l Iij lens 16yl
The excitation current of N is increased sequentially in a straight-striped manner in the same manner as in the case of the 15x quadrupole lens, and the conversion fJ shows the maximum value.
Detects the excitation current and holds its value.
このにうにして、電子線を最小錯乱円に保−）だ状態で
×ｙ型型態点収差補正装置調整されるので、対物レンズ
その他の光学系に起因する非点収差の正確な補正が行わ
れる。又この状態′ｃ４；Ｌ対物レンズ電流値と変換信
号どの関係が第５図のＪ：うに二つのピーク値を右りる
波形から第４図のよう４１甲−のピーク値を有する波形
に変化し−（いるので、中火制御回路２１はスイッチＳ
３をＦＵび”ａ １１１＋１端了に接続して、ステップ
可変回路１つにＪ、る２回目の焦点合わし調整を行う。In this way, the xy-type point aberration corrector is adjusted while keeping the electron beam within the circle of least confusion, so astigmatism caused by the objective lens and other optical systems can be corrected accurately. It will be done. Also, in this state 'c4: What is the relationship between the L objective lens current value and the conversion signal? The waveform that has two peak values of J in Figure 5 changes to the waveform that has a peak value of 41 A as shown in Figure 4. (Therefore, the medium heat control circuit 21 is set to switch S.
3 to the FU and "a 111+1 end" to perform the second focusing adjustment to one step variable circuit.
この２回ト１の焦点合わｌ調整は前述した１回目の方式
にＪ、る焦点合わＵであって−ｂよいが、従来の方式即
ら変換イバン）がＪｒＡ人値を示すときの３・１物レン
ズ電流ｔｌご設定りる方式のものであっＣも差し支えな
い。This two-step focusing adjustment is equivalent to the first method described above, but it is good to have a focusing U of -b. It is a type that allows you to set the single-object lens current tl, so C is also acceptable.
以十のようにしく第８図の実施例装置によれば非点収差
の補正をも含めたｉ’ａ％儒４１が、味にお（）る自動
焦点合わμが行われるので、走査電子粕微鏡を最適系１
′１で使用りるために必要’：ｉ： ；ＩＬ！Ｊ整１＠
ｆｌが従来に比較しＣ′著しく軒減される。As described above, according to the apparatus of the embodiment shown in FIG. Optimal system for lees microscopy 1
'Necessary for use in 1': i: ;IL! J Seiichi 1@
fl is significantly reduced compared to the conventional case.
尚、本発明は第８３図の実施例’Ａ ｆｌＪに限定され
るものｒ ｔ、Ｌなく、例えば土）ホし／、−２１ｉ’
ｉ＋ １１の焦点合わけ調整が完了したｔνに再度非点
収差補正の調整を打つ（もＪ、く、逆に２回目の焦点合
わｔ！調整を省略したり、自動輝度コン１ヘラス］〜調
整回路２０を設置ノずに省略したりりることも１り能で
ある。成るいは非Ｊ：ａ収差補ｊｌ−装買に夕・ｊする
調整Ｉ幾構を設【ノずλ・ｊ物しンスに対する調整機構
のみを設けた装置であっても従来の焦点合わせ装動上す
し正確な焦点合わＩ！を行うく二とが′Ｃ′さる。又、
実メ廟例装詔の変換信号どして映１５！信号に含Ｊｊれ
るｌ：ｌｉ周波成分の最大値又ＬＬ梢梓１１０を用いた
が、ｊｌ−シい焦点では映像信号のピーク圃が高くなる
ことに着目して、映像イｎ＠の１極１ノ１又は負イセ性
への変化分を一定時間にねたっ゛（積算した１１１１を
用いることもできる。更にスアップ可変回Ｖ８１９は対
物レンズ又ｔ；Ｌ ４極レンズへの励磁電流をステップ
状に増減させているが、連続的に増減さｌ！る方式のも
のを採用−りることも容易である。Note that the present invention is limited to the embodiment 'A flJ shown in FIG.
Adjust the astigmatism correction again at tν when the focusing adjustment of i+ 11 is completed. It is also possible to omit or omit the circuit 20 without installing it.Alternatively, it is possible to install a number of adjustment circuits for adjusting the aberration compensation jl-equipment. Even if the device is equipped with only an adjustment mechanism for the focus, it is still necessary to use a conventional focusing device to achieve accurate focusing.Also,
What is the conversion signal of the real edict? The maximum value of the l:li frequency component included in the signal was used, and the LL Kozue Azusa 110 was used, but focusing on the fact that the peak field of the video signal becomes high at a jl-sh focal point, the single pole of the video in@ It is also possible to use the integrated value 1111 for a certain period of time to calculate the change to 1 to 1 or negative bias.Furthermore, the step-up variable turn V819 changes the excitation current to the objective lens or the L quadrupole lens in steps. However, it is also easy to adopt a system that increases and decreases continuously.
以十のＪ、うに、本発明にＪ、れば、ル杏電子顕微鏡、
イＡンマイクロアノーライ１アー、電子ビーム露光装置
装防のように荷電粒子線を細く集束さＵだ状態で使用す
る荷電粒子線装置の焦点合わ（！操作を高い信頼度で自
動化することが可能と４１す、荷電粒子線装置の操作上
の白土に大きな効果が１５１られる。J, uni, the present invention, J, le, an electron microscope,
Ian Microanoriser 1, focusing (! operation) of charged particle beam equipment that uses a finely focused charged particle beam, such as an electron beam exposure equipment, can be automated with high reliability. If possible, it would have a great effect on the operation of charged particle beam devices.
第１゛図は従来の自動焦点合わｉ！装置を１品えたン［
査電子顕微鏡を示す略図、第２図乃至第１図は自動焦点
合わＵの原理を説明するだめの略図、第５図乃至第７図
は非点収差の影響とその補正方法を説明するだめの略図
、第８図は本発明の一実施例装動を示Ｊ略図、第９図及
び第１０図は第８図の装置の動作を説明覆るＩこめの略
図である。
１：電子銃、３，４：集束レンズ、８：検出ｊ！：Ｓ、
１１：走査電源、１２：可変増幅器、１３：励｛公電源
、１４：自動焦点合わけ回路、１！ｉＸ，’１５ｙ：ｌ
１４１レンズ、１６：非点補■回路、１７．１Ｅ３＝電
流１．■整回路、１９：スデップ用変回路、２０：自動
輝石−１ン１・ラス｛・調整回路、２１：中央制御回路
。
特γ１出願人
株式会着１二１電子デクニクス
代表者 太 ［Ｔｌ 進
ｆ）灸イ言号Figure 1 shows the conventional automatic focusing i! I got one piece of equipment [
Figures 2 to 1 are schematic diagrams showing the scanning electron microscope. Figures 2 to 1 are schematic diagrams for explaining the principle of automatic focusing U. Figures 5 to 7 are diagrams for explaining the effects of astigmatism and its correction method. FIG. 8 is a schematic diagram illustrating the operation of an embodiment of the present invention, and FIGS. 9 and 10 are schematic diagrams illustrating the operation of the apparatus of FIG. 8. 1: Electron gun, 3, 4: Focusing lens, 8: Detection j! :S,
11: Scanning power supply, 12: Variable amplifier, 13: Excitation {public power supply, 14: Automatic focusing circuit, 1! iX,'15y:l
141 lens, 16: Astigmatism ■circuit, 17.1E3=current 1. ■Adjustment circuit, 19: Variation circuit for SDP, 20: Automatic pyroxene-1-1-las {・Adjustment circuit, 21: Central control circuit. Special γ1 Applicant Stock Meeting 121 Electronic Dekunics Representative Tai [Tl Shinf) Moxibustion I Word Name
Claims (1)
により試Ｆｉ１面十で微小なビーム径が形成されるよう
に無口・１りると共に試料面」を走査し、該走査と同期
した像表示手段に試料か［）検出された映像信号を用い
た走査像を表示づる装置にｄ３いで、前記粒子線の試１
′＋１面十におけるビーム径に対応する変換信号を前記
映像信号に基づいて１りる手段と、前記集束１ノンズの
レンズ強度を順次変化させたとさに１りｌうれる前記変
換信号の最大伯、しりも所定帛低い変換信号が１ｑられ
る前記集束レンズのレンズ強１１Ｊ−（＋−１，１２）
を求める手段と、前記集束レンズのレンズ強度を Ｌ’
ｌ±Ｌ２ に設、ヒ゛リ−る手段を具備りる荷電粒子
線装置にお（プる自動焦点合わ、ｌ装置。 ２、前記粒子線の試料面一ににＪ３ｔＪるビーム径に対
応りる変換信号を前記映像信号に基づいて得る手段に、
前記映像信号のレベルとコントラスト定のｑし回内に自
動設定りる回路を組み込Δ，だ’１７＋ ａ’１請求の
範囲第′１項記載の前電粒子線装巨にＪ３ １Ｊる自動
焦点合わｔ！装置。 ３、荷電粒子線源から発生する粒子線を集束レンズ及び
ｘｙ型非点補正装貿にｊ、り試料面．１で微小４「ビー
ム径が形成されるように照Ｑ’ｌ するど共に、該粒子
線ににって試料面上を走査し、該走査と同期した像表示
手段に試ｌｉｔから検出され・ｌ、二映像悄′；５を供
給して走査像を表示Ｊる装置に（１′）いて、前記粒子
線の試料面上におりるビーム径にス・ｊ応りる変換信号
を前記映像信号に基づい′Ｃ得る手段ど、前記集束レン
ズのレンス′強度を順次変化さＬＩＩＪときに得られる
前記変換信号の最大値より一ｔ）所定Ｇ１少い変換信号
が得られる前記集束レンズのレンズ強度（Ｌ．１．１２
）を求める手段と、前記集束レンズのレンズ強度を Ｌ
１＋Ｌ２ に設定するＪ一段ど、前乙 記×ｙ型非点補正装勧にお（プる二つの補正信号弾１１
を順次変化させて前記変換信号が最大どなるように設定
する非点補正制御手段を具備したことを９″１徴どする
侑７ｆｉ ｆｌ’ｌ ｒ−線負買にお【ノる自動焦点合
わせ装置。A particle beam generated from a 1.4Xl electric particle beam source is scanned over the sample surface with a silent lens so that a minute beam diameter is formed on one surface of the sample using a focusing lens, and an image is generated in synchronization with the scanning. At d3, test 1 of the particle beam is displayed on a device that displays a scanned image using the detected video signal of the sample on the display means.
The maximum ratio of the converted signal obtained by means of calculating a converted signal corresponding to the beam diameter in the +1 plane based on the video signal and by sequentially changing the lens strength of the focusing lens. , the lens strength 11J-(+-1,12) of the focusing lens to which a predetermined lower conversion signal is 1q
and the lens strength of the focusing lens L'
A charged particle beam device is installed at 1 ± L2, and is equipped with automatic focusing, 1 device. 2. Conversion corresponding to the beam diameter of means for obtaining a signal based on the video signal;
Incorporating a circuit for automatically setting the level and contrast of the video signal in the predetermined range Δ, DA'17+a'1 The electric particle beam device according to claim '1 is automatically set to J31J. Focus! Device. 3. A particle beam generated from a charged particle beam source is passed through a focusing lens and an xy-type astigmatism correction device onto the sample surface. At the same time, the sample surface is scanned by the particle beam, and detected from the sample by the image display means synchronized with the scanning. A device (1') for displaying a scanned image by supplying an image with two images, converts a conversion signal corresponding to the beam diameter of the particle beam onto the sample surface into the image. The means for obtaining 'C' based on the signal sequentially changes the lens 'intensity of the focusing lens such that a conversion signal that is 1t) less than the maximum value of the conversion signal obtained when (L.1.12
) and the lens strength of the focusing lens as L
1 + L2, J 1st step, x y type astigmatism correction is recommended (Pull two correction signal bullets 11)
The automatic focusing device is equipped with astigmatism correction control means for sequentially changing the conversion signal to set the maximum value of the conversion signal. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57157927A JPS5946745A (en) | 1982-09-09 | 1982-09-09 | Automatic focal point aligning unit for charged particle beam device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57157927A JPS5946745A (en) | 1982-09-09 | 1982-09-09 | Automatic focal point aligning unit for charged particle beam device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5946745A true JPS5946745A (en) | 1984-03-16 |
| JPH0255899B2 JPH0255899B2 (en) | 1990-11-28 |
Family
ID=15660507
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57157927A Granted JPS5946745A (en) | 1982-09-09 | 1982-09-09 | Automatic focal point aligning unit for charged particle beam device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5946745A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61191866U (en) * | 1985-05-20 | 1986-11-29 | ||
| JPH01220351A (en) * | 1988-02-27 | 1989-09-04 | Jeol Ltd | Automatic focusing of scanning type electron microscope or the like |
| JPH01231251A (en) * | 1988-03-09 | 1989-09-14 | Hitachi Ltd | Focusing device of electron microscope |
| JPH01239742A (en) * | 1988-03-17 | 1989-09-25 | Nichidenshi Tekunikusu:Kk | Automatic focus control device of scanning electron microscope |
| WO2004030056A1 (en) * | 2002-09-24 | 2004-04-08 | Nikon Corporation | Method for correcting astigmatism, method for determining astigmatic sensitivity and method for exposure in charged particle beam aligner |
-
1982
- 1982-09-09 JP JP57157927A patent/JPS5946745A/en active Granted
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61191866U (en) * | 1985-05-20 | 1986-11-29 | ||
| JPH01220351A (en) * | 1988-02-27 | 1989-09-04 | Jeol Ltd | Automatic focusing of scanning type electron microscope or the like |
| JPH01231251A (en) * | 1988-03-09 | 1989-09-14 | Hitachi Ltd | Focusing device of electron microscope |
| JPH01239742A (en) * | 1988-03-17 | 1989-09-25 | Nichidenshi Tekunikusu:Kk | Automatic focus control device of scanning electron microscope |
| WO2004030056A1 (en) * | 2002-09-24 | 2004-04-08 | Nikon Corporation | Method for correcting astigmatism, method for determining astigmatic sensitivity and method for exposure in charged particle beam aligner |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0255899B2 (en) | 1990-11-28 |
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