JPH07122221A - Split type sensor - Google Patents
Split type sensorInfo
- Publication number
- JPH07122221A JPH07122221A JP5268590A JP26859093A JPH07122221A JP H07122221 A JPH07122221 A JP H07122221A JP 5268590 A JP5268590 A JP 5268590A JP 26859093 A JP26859093 A JP 26859093A JP H07122221 A JPH07122221 A JP H07122221A
- Authority
- JP
- Japan
- Prior art keywords
- electron beam
- signal
- multiplication factor
- detection element
- amplifier
- 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 claims description 39
- 238000001514 detection method Methods 0.000 claims description 23
- 230000003321 amplification Effects 0.000 abstract 2
- 238000003199 nucleic acid amplification method Methods 0.000 abstract 2
- 238000000034 method Methods 0.000 abstract 1
- 230000005540 biological transmission Effects 0.000 description 11
- 230000005381 magnetic domain Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 239000000696 magnetic material Substances 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 241001669679 Eleotris Species 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005672 electromagnetic field Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000013507 mapping Methods 0.000 description 1
- 229910000889 permalloy Inorganic materials 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 238000004627 transmission electron microscopy Methods 0.000 description 1
Landscapes
- Control Of Amplification And Gain Control (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、走査透過電子顕微鏡に
搭載され、透過電子ビームの偏向や強度を検出する分割
型検出器に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a split type detector mounted on a scanning transmission electron microscope for detecting the deflection and intensity of a transmitted electron beam.
【０００２】[0002]
【従来の技術】走査透過電子顕微鏡は、電子ビームを非
常に小さく絞ることができるため、電子ビームが試料を
透過するときに受けるローレンツ力による偏向を検出す
ることにより、試料内部のミクロな電磁気的構造を高い
分解能で調べることができる。この電子ビームの偏向量
は試料に入射する電子ビームの開き角よりも小さいた
め、偏向量の検出には以下のような原理に基づいた検出
器が使われる。すなわち、電子ビームの透過強度を検出
できる検出素子の電子ビーム入射面を光軸を含む面で四
分割し、それぞれが独立に強度を出力できるようにして
おく。ローレンツ力による電子ビームの偏向がない場合
には、検出素子分割部分の中心に透過電子ビームが入射
するように電子顕微鏡の光学系を調整し、各分割部分か
らの信号強度が等しくなるようにしておく。電子ビーム
に偏向が起こると検出素子の各分割部分に入る電子ビー
ム強度が変化するので、各分割部分からの信号の差を演
算することにより、偏向の方向と大きさを検出すること
ができる。同時に、各分割部分からの信号の和を演算す
ることにより、透過強度を検出することもできる。2. Description of the Related Art A scanning transmission electron microscope is capable of narrowing an electron beam very small. Therefore, by detecting the deflection due to the Lorentz force which the electron beam receives when passing through the sample, a micro electromagnetic field inside the sample is detected. The structure can be examined with high resolution. Since the deflection amount of this electron beam is smaller than the aperture angle of the electron beam incident on the sample, a detector based on the following principle is used to detect the deflection amount. That is, the electron beam incident surface of the detection element capable of detecting the transmission intensity of the electron beam is divided into four by the surface including the optical axis so that each can independently output the intensity. If there is no deflection of the electron beam due to Lorentz force, adjust the optical system of the electron microscope so that the transmitted electron beam is incident on the center of the divided part of the detection element, and make the signal intensity from each divided part equal. deep. When the electron beam is deflected, the intensity of the electron beam entering each divided portion of the detection element changes, and therefore the direction and magnitude of the deflection can be detected by calculating the difference between the signals from each divided portion. At the same time, the transmission intensity can also be detected by calculating the sum of the signals from each divided portion.
【０００３】実際に用いられている検出器の電子ビーム
検出素子の分割の数は４に限らず、またその形状も種々
のものが考案されている。そして、検出素子の電子ビー
ム強度を電気信号に変換する部分には、光電子増倍管や
半導体検出器等が用いられている。例えば、ジャーナル
オブ アプライド フィジックス、第６９巻（1991
年）６０７８頁−６０８３頁、(Journal of Applied Ph
ysics 69 (1991) 6078−6083,Mapping induction distr
ibutions by transmission electron microscopy）で
は、透過した電子ビームの偏向を８分割型の半導体検出
器で検出しており、パーマロイ薄膜の枕木磁壁を観察し
ている。The number of divisions of the electron beam detecting element of the detector actually used is not limited to four, and various shapes have been devised. Then, a photomultiplier tube, a semiconductor detector, or the like is used in a portion for converting the electron beam intensity of the detection element into an electric signal. For example, Journal of Applied Physics, Volume 69 (1991).
Year) 6078-6083, (Journal of Applied Ph.
ysics 69 (1991) 6078−6083, Mapping induction distr
In ibutions by transmission electron microscopy, the deflection of the transmitted electron beam is detected by an 8-segment semiconductor detector, and the sleeper domain wall of the permalloy thin film is observed.
【０００４】[0004]
【発明が解決しようとする課題】ところが、観察試料に
孔があいている場合のように、電子ビームの透過強度が
部分的に非常に大きくなる試料を、上述した分割型検出
器を備えた走査透過電子顕微鏡により観察する場合は、
以下のような問題が発生する。大強度の電子ビームが検
出素子に入射すると検出器素子の増倍率が一時的に低下
してしまう。電子ビームの強度がさらに大きくなるとこ
の検出素子は飽和してしまう。この影響は電子ビーム強
度が元に戻ってもしばらく残り、信号の増倍率低下やベ
ースラインシフトをもたらす。また、これらの影響の大
きさや持続時間は、検出素子の各分割部分で異なる。し
たがって、各分割部分からの信号の差をこのまま演算す
ると、上述した部分の変動がさらに強調されて現れてし
まう。このため、増倍率低下やベースラインシフトの影
響が残っている間は、分割型検出器において、電子ビー
ム偏向に対応する正確な差信号が得られなくなってしま
う。However, as in the case where the observation sample has a hole, a sample in which the transmission intensity of the electron beam is extremely large is partially scanned with the above-mentioned split type detector. When observing with a transmission electron microscope,
The following problems occur. When a high-intensity electron beam is incident on the detection element, the multiplication factor of the detector element temporarily decreases. If the intensity of the electron beam is further increased, the detection element will be saturated. This effect remains for a while even if the electron beam intensity returns to its original value, resulting in a decrease in signal multiplication factor and a baseline shift. Further, the magnitude and duration of these influences are different in each divided portion of the detection element. Therefore, if the signal difference from each divided portion is calculated as it is, the above-described variation of the portion is further emphasized and appears. Therefore, while the influence of the reduction of the multiplication factor or the baseline shift remains, the split detector cannot obtain an accurate difference signal corresponding to the electron beam deflection.
【０００５】本発明の目的は、電子ビーム透過強度の変
化が大きな試料を観察しても、常にビーム偏向に対応し
た差信号の得られる走査透過電子顕微鏡用の分割型検出
器を提供することにある。An object of the present invention is to provide a split type detector for a scanning transmission electron microscope which can always obtain a difference signal corresponding to beam deflection even when observing a sample having a large change in electron beam transmission intensity. is there.
【０００６】[0006]
【課題を解決するための手段】本発明の目的を達成する
ために、検出素子の分割部分それぞれに、強度が既知の
基準信号を供給する機能、およびその基準信号に応じて
各分割部分が出力する信号を基にして検出器内増幅器の
増倍率を変化させる機能を付加した。In order to achieve the object of the present invention, the function of supplying a reference signal of known intensity to each of the divided portions of the detection element, and each divided portion outputs according to the reference signal. The function to change the multiplication factor of the amplifier in the detector based on the signal is added.
【０００７】[0007]
【作用】分割型検出器の電子ビーム入射面に一定強度の
光などの基準信号を供給し、その基準信号に伴う主増幅
器の出力が一定レベルとなるよう、この主増幅器の増倍
率を変化させる。これにより、例えば非常に強い電子ビ
ームが入射し、検出素子の利得が一時的に低下した場合
でも、主増幅器の出力と電子ビーム強度の比は一定に保
つことができる。したがって、分割型検出器より得られ
る差信号が、常に電子ビームの偏向量に対応するように
なる。A reference signal such as light having a constant intensity is supplied to the electron beam incident surface of the split type detector, and the multiplication factor of the main amplifier is changed so that the output of the main amplifier accompanying the reference signal becomes a constant level. . Thereby, for example, even when a very strong electron beam is incident and the gain of the detection element is temporarily reduced, the ratio between the output of the main amplifier and the electron beam intensity can be kept constant. Therefore, the difference signal obtained from the split type detector always corresponds to the deflection amount of the electron beam.
【０００８】[0008]
【実施例】図１は、本発明による分割型検出器を備えた
走査透過電子顕微鏡のブロック図である。電子ビーム１
００は照射レンズ１０２により収束され、偏向器１０４
により走査されて試料１０５上に照射される。試料１０
５を透過した電子ビーム１００は、螢光体を塗布したア
クリル性のライトガイドと光電子増倍管の組を、四つ合
わせて構成された検出素子１０８内に入り電気信号に変
換される。そしてこの電気信号は四つの独立な増幅器に
より増幅される。電子ビーム１００を走査するための偏
向回路５２からの信号はパルス発生器５３へも送られ、
そこでチョッピング電極１０９、および発光ダイオード
６０を駆動する信号が作られる。1 is a block diagram of a scanning transmission electron microscope equipped with a split type detector according to the present invention. Electron beam 1
00 is converged by the irradiation lens 102, and the deflector 104
The sample 105 is scanned and irradiated onto the sample 105. Sample 10
The electron beam 100 that has passed through 5 enters a detection element 108 that is formed by combining four sets of a phosphor-coated acrylic light guide and a photomultiplier tube, and is converted into an electric signal. This electrical signal is then amplified by four independent amplifiers. The signal from the deflection circuit 52 for scanning the electron beam 100 is also sent to the pulse generator 53,
Then, a signal for driving the chopping electrode 109 and the light emitting diode 60 is generated.
【０００９】図２は、この分割型検出器の詳細図であ
る。検出素子１０８の分割部分から得られた信号は、前
置増幅器６１，主増幅器６２により増幅される。電子ビ
ーム１００をチョッピングし、検出素子１０８に入射し
ないようにしたときに、電子ビーム１００入射面に接着
された発光ダイオード６０からの光を検出素子１０８に
入れる。この時に発生した信号だけを増倍率調整器６３
であらかじめ設定した基準レベルと比較し、主増幅器６
２の出力レベルが一定となるように主増幅器６２に負帰
還をかける。その後、チョッピングしていた電子ビーム
１００を再び検出素子１０８上に戻し、得られる信号を
演算器６４において演算する。演算により得られた差信
号は電子ビーム１００の偏向量に対応し、和信号は透過
強度に対応する。FIG. 2 is a detailed view of this split type detector. The signal obtained from the divided portion of the detection element 108 is amplified by the preamplifier 61 and the main amplifier 62. When the electron beam 100 is chopped so as not to enter the detection element 108, the light from the light emitting diode 60 adhered to the incident surface of the electron beam 100 enters the detection element 108. Only the signal generated at this time is multiplied by the multiplication factor adjuster 63.
The main amplifier 6 is compared with the reference level set in advance.
Negative feedback is applied to the main amplifier 62 so that the output level of 2 becomes constant. After that, the chopped electron beam 100 is returned to the detection element 108 again, and the obtained signal is calculated by the calculator 64. The difference signal obtained by the calculation corresponds to the deflection amount of the electron beam 100, and the sum signal corresponds to the transmission intensity.
【００１０】図３は、制御信号の流れ図である。電子ビ
ーム１００走査のための信号が１ステップ進んだ直後
に、ビームチョッピング、および発光ダイオード６０の
駆動信号を発生する。このとき、増倍率調整器６３にゲ
ートをかけ、その時間だけ基準レベルと比較する。ゲー
トのかかっていないときに入ってきた信号は、直前に決
まった増倍率で出力される。ベースラインのずれは、ビ
ームチョッピング後、発光ダイオード６０が発光するま
での時間にベースラインレベルを測定しておくことによ
り決めることができる。FIG. 3 is a flow chart of control signals. Immediately after the signal for scanning the electron beam 100 advances by one step, beam chopping and a drive signal for the light emitting diode 60 are generated. At this time, the multiplication factor adjuster 63 is gated and compared with the reference level only for that time. The signal that comes in when the gate is not applied is output with the multiplication factor determined immediately before. The deviation of the baseline can be determined by measuring the baseline level before the light emitting diode 60 emits light after the beam chopping.
【００１１】図４に、本実施例による分割型検出器で計
測した磁性体試料１０５の磁区像と、増倍率調整なしに
観察した磁区像とを比較した図を示す。図４（ａ）は増
倍率調整なしに観察した磁区像で、試料の孔があいてい
る部分より後ろで、ビームが走査される部分（孔の右
側）に余分なコントラストが付いている。図４（ｂ）
は、図４（ａ）と同じ部分を増倍率調整を行って観察し
た磁区像で、孔の右の部分でも余分なコントラストは付
いていない。FIG. 4 shows a diagram comparing the magnetic domain image of the magnetic material sample 105 measured by the split type detector according to this embodiment with the magnetic domain image observed without adjusting the multiplication factor. FIG. 4 (a) is a magnetic domain image observed without adjusting the multiplication factor, and there is extra contrast in the portion (right side of the hole) where the beam is scanned after the portion where the hole of the sample is open. Figure 4 (b)
4A is a magnetic domain image obtained by observing the same portion as in FIG. 4A by adjusting the multiplication factor, and there is no extra contrast even in the right portion of the hole.
【００１２】以上、実施例にそって本発明を説明した
が、増倍率調整器から帰還をかける先は主増幅器に限る
ものではなく、検出素子、または増倍率調整用に設けた
副増幅器でも良い。Although the present invention has been described with reference to the embodiments, the destination of feedback from the multiplication factor adjuster is not limited to the main amplifier, but may be a detection element or a sub-amplifier provided for adjusting the multiplication factor. .
【００１３】また、本実施例では基準信号を発光ダイオ
ード６０から得られる一定強度の光としたが、他の発光
手段、あるいは他の基準信号を用いることも可能であ
る。Further, in the present embodiment, the reference signal is light of a constant intensity obtained from the light emitting diode 60, but it is also possible to use another light emitting means or another reference signal.
【００１４】さらに、本実施例では四つの信号を、基準
レベルを使ってそれぞれ独立に制御したが、検出素子分
割部分の一つからの信号を基準にして、その信号と同じ
出力信号となるように他の信号を制御することもでき
る。この場合、和信号は増倍率変化の影響を受ける欠点
があるものの、回路の数を一つ減らせる利点がある。Further, in the present embodiment, the four signals are controlled independently by using the reference level, but the same output signal as that signal is obtained with reference to the signal from one of the detection element division parts. It is also possible to control other signals. In this case, the sum signal has the drawback of being affected by the change in multiplication factor, but has the advantage of reducing the number of circuits by one.
【００１５】[0015]
【発明の効果】本発明によれば、分割型検出器に入射す
る電子ビームが試料の孔などにより一時的に非常に強く
なって、検出素子に飽和などが起こり、増倍率が一時的
に低下しても、その直後から電子ビーム偏向に対応した
正しい差信号を得ることができる。According to the present invention, the electron beam incident on the split-type detector becomes temporarily very strong due to the holes in the sample, and saturation occurs in the detection element, so that the multiplication factor temporarily decreases. However, the correct difference signal corresponding to the electron beam deflection can be obtained immediately after that.
【図１】本発明の実施例の分割型検出器を備えた、走査
透過電子顕微鏡の全体図である。FIG. 1 is an overall view of a scanning transmission electron microscope equipped with a split type detector according to an embodiment of the present invention.
【図２】本発明の実施例の分割型検出器のブロック図。FIG. 2 is a block diagram of a split type detector according to an embodiment of the present invention.
【図３】本発明の実施例の分割型検出器の制御信号のタ
イミングチャート。FIG. 3 is a timing chart of control signals of the split type detector according to the embodiment of the present invention.
【図４】本発明の実施例および従来例による磁性体試料
の磁区像の説明図。FIG. 4 is an explanatory diagram of a magnetic domain image of a magnetic material sample according to an example of the present invention and a conventional example.
５１…演算回路、５２…偏向回路、５３…パルス発生
器、１００…電子ビーム、１０４…偏向器、１０８…検
出素子、１０９…チョッピング電極。51 ... Arithmetic circuit, 52 ... Deflection circuit, 53 ... Pulse generator, 100 ... Electron beam, 104 ... Deflector, 108 ... Detection element, 109 ... Chopping electrode.
Claims (2)
検出素子，上記検出素子の各分割部分からの信号をそれ
ぞれ独立に増幅することのできる増幅器，上記増幅器か
らの上記各分割部分に対応する信号の和および差を演算
して出力する演算器から構成される分割型検出器におい
て、上記分割部分のそれぞれに強度が既知の基準信号を
供給する手段と、上記基準信号の供給に伴い上記増幅器
が出力する上記検出素子の各分割部分に対応する信号の
それぞれが、あらかじめ設定したレベルとなるよう上記
増幅器の増倍率を調整する機構を備えたことを特徴とす
る分割型検出器。1. A detection part corresponding to an electron beam detection element in which the detection part is divided into a plurality of parts, an amplifier capable of independently amplifying a signal from each division part of the detection element, and each division part from the amplifier. A detector for calculating the sum and difference of the signals to be output and outputting the calculated reference signal having a known intensity to each of the divided portions; A split-type detector comprising a mechanism for adjusting the multiplication factor of the amplifier so that each of the signals output from the amplifier and corresponding to each divided portion of the detection element has a preset level.
これによる上記増倍率調整の実行タイミングを外部から
制御する機構，被検出電子ビームと上記基準信号とを交
互に供給する機構、を合わせて用いることにより、上記
被検出電子ビームに対応する上記演算器の出力結果を、
上記被検出電子ビームの直前に供給した上記基準信号に
基づく上記増倍率の上記増倍率調整により補正する分割
型検出器。2. A combination of a mechanism for externally controlling the supply of the reference signal and an execution timing of the multiplication factor adjustment thereby, and a mechanism for alternately supplying the detected electron beam and the reference signal. By using the output result of the arithmetic unit corresponding to the detected electron beam,
A split type detector for correcting the multiplication factor based on the reference signal supplied immediately before the detected electron beam by the multiplication factor adjustment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5268590A JPH07122221A (en) | 1993-10-27 | 1993-10-27 | Split type sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5268590A JPH07122221A (en) | 1993-10-27 | 1993-10-27 | Split type sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH07122221A true JPH07122221A (en) | 1995-05-12 |
Family
ID=17460650
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5268590A Pending JPH07122221A (en) | 1993-10-27 | 1993-10-27 | Split type sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07122221A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2443279A (en) * | 2006-07-18 | 2008-04-30 | Applied Materials Inc | Beam stop for an ion implanter |
| JP2009277619A (en) * | 2008-05-19 | 2009-11-26 | Jeol Ltd | Sample analysis method using scanning transmission electron microscope |
| JP2011243516A (en) * | 2010-05-21 | 2011-12-01 | Univ Of Tokyo | Adjustment method of multiple division stem detector |
-
1993
- 1993-10-27 JP JP5268590A patent/JPH07122221A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2443279A (en) * | 2006-07-18 | 2008-04-30 | Applied Materials Inc | Beam stop for an ion implanter |
| JP2009277619A (en) * | 2008-05-19 | 2009-11-26 | Jeol Ltd | Sample analysis method using scanning transmission electron microscope |
| JP2011243516A (en) * | 2010-05-21 | 2011-12-01 | Univ Of Tokyo | Adjustment method of multiple division stem detector |
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