JPS6378443A - Electron beam focusing device - Google Patents
Electron beam focusing deviceInfo
- Publication number
- JPS6378443A JPS6378443A JP22084886A JP22084886A JPS6378443A JP S6378443 A JPS6378443 A JP S6378443A JP 22084886 A JP22084886 A JP 22084886A JP 22084886 A JP22084886 A JP 22084886A JP S6378443 A JPS6378443 A JP S6378443A
- Authority
- JP
- Japan
- Prior art keywords
- electron beam
- objective lens
- sample
- scanning
- current
- 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
- 238000010894 electron beam technology Methods 0.000 title claims abstract description 35
- 230000005284 excitation Effects 0.000 claims description 17
- 238000010586 diagram Methods 0.000 description 5
- 238000001514 detection method Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
Abstract
Description
【発明の詳細な説明】
〔発明の概要〕
本発明は電子ビーム焦点合せ装置に係り、電子ビームを
絶縁膜の形成された試料に照射する際に、対物レンズに
流す励磁電流を変化させながら第１の走査を行ない、次
に第１の走査と直交する方向に一定間隔毎に第１の走査
と同じ変化をさせた励磁電流を対物レンズに流し線走査
を行う、第２の走査を行なうことで、試料から得られる
二次電子の信号波形のうち、最も幅の小さいピークを与
える対物レンズに加える電流を選択し、この電流を合焦
点電流とすることでコントラストのない絶縁膜の形成さ
れた試ｔ［の焦点を求めるようにしたものである。[Detailed Description of the Invention] [Summary of the Invention] The present invention relates to an electron beam focusing device that focuses an electron beam while changing an excitation current flowing through an objective lens when irradiating an electron beam onto a sample on which an insulating film is formed. 1 scan, and then perform a second scan in which the excitation current, which is changed in the same way as the first scan, is passed through the objective lens at regular intervals in a direction perpendicular to the first scan, and a line scan is performed. Then, the current to be applied to the objective lens that gives the smallest peak in the signal waveform of secondary electrons obtained from the sample is selected, and by using this current as the focused current, an insulating film with no contrast is formed. It is designed to find the focus of test t[.
本発明は電子ビーム焦点合せ装置に係り、特に絶縁膜付
のＬＳＩの焦点合せが自動的に行なえる電子ビーム焦点
合せ装置に閏する。The present invention relates to an electron beam focusing device, and particularly to an electron beam focusing device that can automatically focus an LSI with an insulating film.
電子ビームを試料に照射して、試料から放出される二次
電子を分析する電子ビーム装置では、試料として絶縁膜
付のＬＳＩ等を分析する場合が多い。In an electron beam device that irradiates a sample with an electron beam and analyzes secondary electrons emitted from the sample, an LSI or the like with an insulating film is often analyzed as the sample.
この様な絶縁膜付のＬＳＩは配線がみえないため、焦点
合せを行う場合にコントラストがなく、この焦点合せは
非常に難しい問題があった。Since wiring is not visible in such an LSI with an insulating film, there is no contrast when focusing, and this focusing is extremely difficult.
この為に、従来では合焦点とするために絶縁膜付きのＬ
ＳＩ試料にストロボを用い、ある基準位相電圧で電子ビ
ームを試料上に当て、更にこの電圧を変化させた状態で
電子ビームを試料に当て、１画素分の画像パターンを何
十分かかけることで配線パターンを読み出す様にしてい
る。For this reason, in the past, an L
Using a strobe on the SI sample, an electron beam is applied to the sample at a certain reference phase voltage, and then the electron beam is applied to the sample while changing this voltage, and an image pattern for one pixel is applied over several tens of minutes to perform wiring. I am trying to read out the pattern.
上記の様に従来構成では、多くの時間をかけて絶縁膜付
のＬＳＩ等の試料上でパターンを認蟲しているために自
動的に焦点合せを行うことが出来ないだけでなく、殆ん
どの場合は目視で焦点合せを行なっているのが現状であ
るが、この場合は焦点合せを何回か行なって合焦点位置
を設定しなければならない欠点があった。As mentioned above, with the conventional configuration, it takes a lot of time to recognize the pattern on a sample such as an LSI with an insulating film, which not only makes it impossible to automatically focus, but also makes it difficult to focus. In all cases, focusing is currently performed visually, but in this case there is a drawback that focusing must be performed several times to set the focal point position.
本発明は上記の欠点に鑑みなされたもので、その目的と
するところは、絶縁膜付の試料に電子ビームを照射する
と照射領域が帯電し、１時的に周囲と異なった電位とな
ることを利用し、この領域の大小を電子ビームを照射し
た時に生ずる二次電子波形から自動的に合焦点を判定す
ることで合焦点位置電流を設定するようにしたものであ
る。The present invention was made in view of the above-mentioned drawbacks, and its purpose is to prevent the irradiation area from becoming electrically charged when an electron beam is irradiated onto a sample with an insulating film, and to temporarily have a potential different from that of the surrounding area. By utilizing the size of this region and automatically determining the focal point from the secondary electron waveform generated when the electron beam is irradiated, the focal point position current is set.
本発明の電子ビーム焦点合せ装置は第１図に示すように
、電子ビーム源１から試料７に照射する電子ビーム２に
よって、試料７から放出される二次電子６を検出する電
子ビーム装置に於いて、試料７上に照射する電子ビーム
２を対物レンズ４に流す励磁電流を変化させながら第１
のデジタル的な線走査１８を行なう第１の走査手段３，
８．９と、第１の走査手段３，８．９による試料７表面
状態変化領域幅を測定するため、第１の線走査と直交す
る方向に、且つ一定間隔毎に第１の走査と同様の変化を
する励磁電流で第２の線走査１５を行う第２の走査手段
３，８．９と、この第２の走査手段によって試料７から
得られる二次電子６の信号波のうち、最も幅の小さいピ
ークを与える対物レンズ４に流す電流を対物レンズ４に
加える合焦点電流とするようにしたものである。As shown in FIG. 1, the electron beam focusing device of the present invention is an electron beam device that detects secondary electrons 6 emitted from a sample 7 by an electron beam 2 irradiated onto the sample 7 from an electron beam source 1. the electron beam 2 to be irradiated onto the sample 7 while changing the excitation current flowing through the objective lens 4.
first scanning means 3 for performing digital line scanning 18 of
8.9, and in order to measure the width of the surface state change area of the sample 7 by the first scanning means 3 and 8.9, the same scanning as the first scanning is performed in the direction orthogonal to the first line scanning and at regular intervals. The second scanning means 3, 8.9 performs the second line scanning 15 with an excitation current that changes, and the signal wave of the secondary electron 6 obtained from the sample 7 by this second scanning means, The current flowing through the objective lens 4 which gives a narrow peak is used as the focused current applied to the objective lens 4.
本発明の電子ビーム焦点合せ装置は、コントラストの悪
い試料上に電子ビームによる第１の線走査を施すと１時
的に周囲と異なる電位となって、この部分をみることが
出来るので、第１の線走査を対物レンズに流す励磁電流
を変化させて行ない、次にこの第１の走査方向と直交す
る方向に対物レンズに流す励磁電流を変化させながら所
定間隔で第２の走査を行なって、第１の走査によって生
じた電位の異なる部分の最も小さな幅Ｗを求めて、この
部分の励磁電流を合焦点電流とすることで自動的に焦点
合せが行なえる様にしたものである。When the electron beam focusing device of the present invention performs the first line scan using the electron beam on a sample with poor contrast, the potential temporarily becomes different from that of the surrounding area, and this part can be seen. Line scanning is performed by changing the excitation current flowing through the objective lens, and then a second scan is performed at predetermined intervals while changing the excitation current flowing through the objective lens in a direction perpendicular to the first scanning direction, The smallest width W of the portion where the potentials differ due to the first scanning is determined, and the excitation current of this portion is used as the focusing current, so that focusing can be performed automatically.
以下、本発明の電子ビーム焦点合せ装置の一実施例を第
１図乃至第５図について詳記する。Hereinafter, one embodiment of the electron beam focusing device of the present invention will be described in detail with reference to FIGS. 1 to 5.
第１図に於いて、電子ビーム源である電子銃１から放出
された電子ビーム２は少（とも線走査偏向器３と対物レ
ンズ４を通して試料７に照射される。In FIG. 1, an electron beam 2 emitted from an electron gun 1 serving as an electron beam source is irradiated onto a sample 7 through a line scanning deflector 3 and an objective lens 4.
試料７に照射した電子ビーム２によって試料７から放出
した二次電子６は二次電子検出器５に与えられ、この二
次電子検出電圧に基づいて各種測定が行なわれているが
、試料に絶縁膜７ａが被着されたＬＳＩ等では配線パタ
ーンが絶縁膜下に配されているためにコントラストが小
さく、電子ビームの焦点を合せることが非常に困難であ
る。Secondary electrons 6 emitted from the sample 7 by the electron beam 2 irradiated on the sample 7 are given to the secondary electron detector 5, and various measurements are performed based on this secondary electron detection voltage. In an LSI or the like on which the film 7a is deposited, the wiring pattern is placed under the insulating film, so the contrast is small and it is very difficult to focus the electron beam.
そこで、走査偏向器３ヘコンピユータエ１から線走査制
御回路９と駆動回路８を介してデジタル的な走査電圧を
加え、第２図の様に試料面に対しＸ軸方向に第１の線走
査１８を行なう。それと同時に励磁電流を励磁回路１０
を介して対物レンズ４に励磁電流を例えば順次大きくな
る様に変化させて加えることで試料７上の電子ビームス
ポット１２ａ、１２ｂ、１２ｃ、１２ｄ・・−１２ｉ・
・・１２．、．１２ｎは順次小さくなり、又順次大きく
なる様な状態で照射される。この結果、第３図に示す様
に試料７の絶縁股上には電子ビームスポット１２ａ、１
２ｂ、１２ｃ、 １２ｄ・−・・１２ｉ・・・１２．
、、．１２ｎの大きさに対応した帯電領域１３を生じて
可視化される。Therefore, a digital scanning voltage is applied from the computer 1 to the scanning deflector 3 via the line scanning control circuit 9 and the drive circuit 8, and the first line scanning is performed in the X-axis direction with respect to the sample surface as shown in FIG. Do step 18. At the same time, the excitation current is supplied to the excitation circuit 10.
By applying an excitation current to the objective lens 4 through the objective lens 4, for example, by changing the excitation current so that it increases sequentially, the electron beam spots 12a, 12b, 12c, 12d, . . . -12i.
...12. ,．． 12n is irradiated in such a manner that it becomes smaller and larger sequentially. As a result, as shown in FIG. 3, electron beam spots 12a, 1
2b, 12c, 12d...12i...12.
,,． A charged region 13 corresponding to the size of 12n is generated and visualized.
次に第１の線走査１８と直交する方向（ｙ軸方向）にコ
ンピュータ１１から線走査制御回路９と駆動回路８を介
して走査偏向器３にデジタル的な第２の線走査１５を行
う。Next, a digital second line scan 15 is performed on the scanning deflector 3 from the computer 11 in a direction perpendicular to the first line scan 18 (y-axis direction) via the line scan control circuit 9 and the drive circuit 8.
この際の電子ビームスポット１４ａ、１４ｂ。Electron beam spots 14a and 14b at this time.
１４ｃ、 ・・ １４ｉ＝１４，１，１４ｎの大きさ
は第１の線走査１８を行った時の径と同じになるように
線走査制御回路９を通じて励磁回路１０の励磁電流を順
次変化させて対物レンズ４の焦点合せを行う。The excitation current of the excitation circuit 10 is sequentially changed through the line scan control circuit 9 so that the sizes of 14c, . . . 14, 1, 14n are the same as the diameter when the first line scan 18 is performed. The objective lens 4 is focused.
第３図に示すように絶縁股上の帯電領域１３は負に帯電
しているのでこの部分の帯電領域幅Ｗを測定するために
第２の線走査が行われる。第３図に示す第２の線走査を
行う電子ビームスポット１４ａ、１４ｂ、１４ｃ、−１
４１・−−１４、、，１４ｎの第２の線走査番号を１．
２．３・・・ｉ・・・ｎ−１，ｎとして第５図に示す様
に横軸にとり、縦軸に帯電領域幅Ｗをとると、曲線１７
に示すようにスポット径の大きい部分即ち、１．２．３
．４及びｎ ３．ｎ ２．ｎ ｌ、ｎ番目等では帯
電領域幅Ｗは大きい。これに対して細いビームで帯電領
域１３を形成し、同じ励磁電流で第２の線走査、即ち細
いビームでｙ軸方向走査を行なった第５図のｉ番目の位
置では帯電領域幅Ｗは最小となる。即ち、第４図の曲線
１６に示す様に横軸にＹ方向位置を縦軸に二次電子検出
器５から得られる二次電子検出信号Ｓをとると、ｉ番目
の第１及び第２の線走査で得られる帯電領域の幅Ｗは二
次電子検出信号Ｓのピーク値の半値幅で求めると最もＷ
の幅が小さくなる。As shown in FIG. 3, the charged region 13 on the insulating crotch is negatively charged, so a second line scan is performed to measure the charged region width W of this portion. Electron beam spots 14a, 14b, 14c, -1 for performing the second line scan shown in FIG.
41.--14, , , 14n second line scanning numbers are set to 1.
2.3...i...n-1,n as shown in FIG. 5 on the horizontal axis and the charged area width W on the vertical axis, curve 17
As shown in 1.2.3, the part with a large spot diameter
．． 4 and n 3. n2. The charged region width W is large at nl, nth, etc. On the other hand, at the i-th position in FIG. 5, where the charged region 13 is formed with a thin beam and the same excitation current is used to perform a second line scan, that is, scan in the y-axis direction with the thin beam, the charged region width W is the minimum. becomes. That is, if we take the secondary electron detection signal S obtained from the secondary electron detector 5 with the Y-direction position on the horizontal axis and the vertical axis as shown by the curve 16 in FIG. 4, the i-th first and second The width W of the charged area obtained by line scanning is determined by the half width of the peak value of the secondary electron detection signal S.
width becomes smaller.
この様にして求めた帯電領域幅Ｗが最小となる励磁電流
を選択して、これを設定して合焦点とする様にすれば絶
縁膜付のＬＳＩの様にコントラストのないものの焦点合
せを捲めて簡単に自動化出来ることになる。By selecting the excitation current that minimizes the charged area width W determined in this way and setting this as the focusing point, it is possible to turn the focusing of objects without contrast, such as LSIs with insulating films. This means that it can be easily automated.
本発明は上記の如く構成し、且つ動作させたので絶縁膜
付のＬＳＩの如く配線パターンのみえないコントラスト
のない試料をも自動的に焦点合せを行うことが可能とな
る特長を有する。Since the present invention is configured and operated as described above, it has the advantage that it is possible to automatically focus even a sample with no contrast, such as an LSI with an insulating film, in which a wiring pattern cannot be seen.
第１図は本発明の電子ビーム焦点合せ装置の系統図、
第２図は試料上のスポットの模式図、
第３図は試料上の帯電領域と第２の走査スポットの関係
を示す模式図、
第４図は帯電領域幅対二次電子検出信号特性図、第５図
は帯電領域幅対第２の線走査番号特性図である。
１・・・電子銃、
２・・・電子ビーム、
３・・・走査偏向器、
４・・・対物レンズ、
５・・・二次電子検出器、
６・・・二次電子、
７・・・試料、
７ａ・・・絶縁膜、
８・・・駆動回路、
９・・・線走査制御回路、
１０・・・励磁回路、
１１・・・コンピュータ。FIG. 1 is a system diagram of the electron beam focusing device of the present invention, FIG. 2 is a schematic diagram of the spot on the sample, and FIG. 3 is a schematic diagram showing the relationship between the charged area on the sample and the second scanning spot. FIG. 4 is a characteristic diagram of charged area width versus secondary electron detection signal, and FIG. 5 is a characteristic diagram of charged area width versus second line scanning number. DESCRIPTION OF SYMBOLS 1...Electron gun, 2...Electron beam, 3...Scanning deflector, 4...Objective lens, 5...Secondary electron detector, 6...Secondary electron, 7... - Sample, 7a... Insulating film, 8... Drive circuit, 9... Line scanning control circuit, 10... Excitation circuit, 11... Computer.
Claims (1)
ム（２）によって、該試料から放出される二次電子（６
）を検出する電子ビーム装置に於いて、 上記試料（７）上に照射する電子ビームを対物レンズ（
４）に流す励磁電流を変化させながら第１の線走査を行
なう第１の走査手段（３、８、９）と、 該第１の走査手段による上記試料表面状態変化領域幅を
測定するため該第１の線走査と直交する方向に、且つ一
定間隔毎に第１の走査と同様の変化をする対物レンズ励
磁電流で第２の線走査を行う第２の線走査手段（３、８
、９）と、 該第２の走査手段によって上記試料から得られる上記二
次電子信号のうち、最も幅の小さいピークを与える対物
レンズに流す電流を対物レンズに加える合焦点電流とす
ることを特徴とする電子ビーム焦点合せ装置。[Claims] Secondary electrons (6) emitted from the sample (7) by the electron beam (2) irradiated from the electron beam source (1) to the sample (7)
), the electron beam irradiated onto the sample (7) is directed through an objective lens (
4) a first scanning means (3, 8, 9) for performing a first line scan while changing the excitation current applied to the first scanning means; A second line scanning means (3, 8
, 9), and a current flowing through the objective lens that gives the smallest peak among the secondary electron signals obtained from the sample by the second scanning means is used as a focused current applied to the objective lens. An electron beam focusing device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22084886A JPS6378443A (en) | 1986-09-20 | 1986-09-20 | Electron beam focusing device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22084886A JPS6378443A (en) | 1986-09-20 | 1986-09-20 | Electron beam focusing device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS6378443A true JPS6378443A (en) | 1988-04-08 |
Family
ID=16757489
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP22084886A Pending JPS6378443A (en) | 1986-09-20 | 1986-09-20 | Electron beam focusing device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6378443A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008102635A1 (en) * | 2007-02-19 | 2008-08-28 | Sii Nanotechnology Inc. | Charged particle beam apparatus and charged particle optical system adjusting method |
| JP2010211973A (en) * | 2009-03-09 | 2010-09-24 | Hitachi High-Technologies Corp | Charged particle beam device |
| WO2020002344A1 (en) * | 2018-06-27 | 2020-01-02 | Carl Zeiss Smt Gmbh | Method and apparatus for examining a beam of charged particles |
-
1986
- 1986-09-20 JP JP22084886A patent/JPS6378443A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008102635A1 (en) * | 2007-02-19 | 2008-08-28 | Sii Nanotechnology Inc. | Charged particle beam apparatus and charged particle optical system adjusting method |
| JP2008204722A (en) * | 2007-02-19 | 2008-09-04 | Sii Nanotechnology Inc | Adjusting method for charged particle beam apparatus and charged particle optical system |
| US8698105B2 (en) | 2007-02-19 | 2014-04-15 | Sii Nanotechnology | Charged particle beam apparatus and method of adjusting charged particle optics |
| JP2010211973A (en) * | 2009-03-09 | 2010-09-24 | Hitachi High-Technologies Corp | Charged particle beam device |
| WO2020002344A1 (en) * | 2018-06-27 | 2020-01-02 | Carl Zeiss Smt Gmbh | Method and apparatus for examining a beam of charged particles |
| US11961705B2 (en) | 2018-06-27 | 2024-04-16 | Carl Zeiss Smt Gmbh | Method and apparatus for examining a beam of charged particles |
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