JP2636381B2 - Electron beam equipment - Google Patents
Electron beam equipmentInfo
- Publication number
- JP2636381B2 JP2636381B2 JP63285273A JP28527388A JP2636381B2 JP 2636381 B2 JP2636381 B2 JP 2636381B2 JP 63285273 A JP63285273 A JP 63285273A JP 28527388 A JP28527388 A JP 28527388A JP 2636381 B2 JP2636381 B2 JP 2636381B2
- Authority
- JP
- Japan
- Prior art keywords
- electron beam
- anode
- sample
- sample irradiation
- diameter
- 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.)
- Expired - Fee Related
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Description
【発明の詳細な説明】 ［産業上の利用分野］ 本発明は電子線装置に関し、特に電界放出型電子銃を
備えた電子線装置に関する。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam apparatus, and more particularly, to an electron beam apparatus having a field emission type electron gun.
［従来の技術］ 近年、熱電子放射型電子銃を備えた走査電子顕微鏡で
は熱電子放射型電子銃の光学特性により、試料照射電流
の減少に伴なって試料照射電子線径が縮小するというこ
とが知られている。そこで、熱電子放射型電子銃を備え
た走査電子顕微鏡においては、高分解能の走査電子顕微
鏡像を得るために、電子顕微鏡の操作者が試料照射電流
を所望の試料照射電流値まで減らすような操作が行なわ
れている。[Prior Art] In recent years, in a scanning electron microscope equipped with a thermionic emission type electron gun, the diameter of the electron beam emitted from the sample decreases with the decrease in the current applied to the sample due to the optical characteristics of the electron gun. It has been known. Therefore, in a scanning electron microscope equipped with a thermionic emission electron gun, in order to obtain a high-resolution scanning electron microscope image, an operator of the electron microscope reduces the sample irradiation current to a desired sample irradiation current value. Is being done.
［発明が解決しようとする課題］ さて、最近では高分解能の高画質の二次電子像を得る
ために電界放出型電子銃を備えた走査電子顕微鏡が頻繁
に用いられている。しかし、電界放出型電子銃を備えた
走査電子顕微鏡では、試料照射電流を減少させても試料
照射電子線系が減少しない領域が実用上存在するため、
前述のような熱電子放射型電子銃を備えた走査電子顕微
鏡を操作する感覚で、単に試料照射電流を減らすことに
よっては高分解能で高画質の走査電子顕微鏡像を得るこ
とはできない。[Problems to be Solved by the Invention] In recent years, a scanning electron microscope equipped with a field emission electron gun has been frequently used in order to obtain a high-resolution, high-quality secondary electron image. However, in a scanning electron microscope equipped with a field emission electron gun, there is a practical area where the sample irradiation electron beam system does not decrease even if the sample irradiation current is reduced.
It is not possible to obtain a high-resolution and high-quality scanning electron microscope image simply by reducing the sample irradiation current as if operating a scanning electron microscope equipped with a thermionic electron gun as described above.
本発明は、上述した課題を考慮し、熟練しない操作者
でも試料照射電子線径を最小にした上で最大の試料照射
電子線電流値の電子線を簡単に試料に照射できる電子線
装置を提供することを目的としている。The present invention has been made in consideration of the above-described problems, and provides an electron beam apparatus that allows even an unskilled operator to easily irradiate a sample with an electron beam having a maximum sample irradiation electron beam current value after minimizing the sample irradiation electron beam diameter. It is intended to be.
［課題を解決するための手段］ 本発明は、陰極と、該陰極との間に引出電界を形成す
るための第１陽極と、陰極から放出され第１陽極を通過
する電子線を加速するための第２陽極と、該第２陽極を
通過した電子線を集束して試料上に照射するための集束
レンズと対物レンズとを備えた電子線装置において、前
記第１陽極と印加される電圧を表す信号と前記第２陽極
へ印加される電圧を表す信号に基づいて試料照射電子線
径を最小且つその最小径の状態で試料照射電子線電流値
を最大とするのに必要な前記集束レンズの励磁量を表す
信号を発生するための手段と、該発生した信号に基づい
て前記集束レンズの励磁を制御する手段とを設けたこと
を特徴とする。Means for Solving the Problems The present invention provides a cathode, a first anode for forming an extraction electric field between the cathode, and an electron beam emitted from the cathode and passing through the first anode. A second anode, and a focusing lens for focusing the electron beam passing through the second anode and irradiating the sample on the sample, and an objective lens. Of the focusing lens necessary to minimize the sample irradiation electron beam diameter and to maximize the sample irradiation electron beam current value in the state of the minimum diameter based on the signal representing the voltage applied to the second anode and the signal representing the voltage applied to the second anode. A means for generating a signal indicating the amount of excitation and means for controlling the excitation of the focusing lens based on the generated signal are provided.
［作用］ 第１陽極へ印加される電圧を表す信号と前記第２陽極
へ印加される電圧を表す信号に基づいて試料照射電子線
径を最小且つ試料照射電子線電流値を最大とするのに必
要な前記集束レンズの励磁量を表す信号を発生するため
の手段を設けると共に、該手段の発生した信号に基づい
て前記集束レンズの励磁を制御するようにして、高分解
能で高画質の走査電子顕微鏡像を得る。[Operation] To minimize the sample irradiation electron beam diameter and maximize the sample irradiation electron beam current value based on the signal representing the voltage applied to the first anode and the signal representing the voltage applied to the second anode. Means for generating a signal representing the required amount of excitation of the focusing lens is provided, and the excitation of the focusing lens is controlled based on the signal generated by the means, so that high-resolution and high-quality scanning electrons are provided. Obtain a microscope image.
［実施例］ 以下、本発明の実施例を図面に基づいて説明する。第
１図は本発明の一実施例を説明するための装置構成図、
第２図は電界放出型電子銃を用いた走査電子顕微鏡にお
ける試料照射電流と試料照射電流径の関係を示す図、第
３図は最小試料照射電子線径と加速電圧の関係を示す
図、第４図は加速電圧と引出電圧に基づいて電子レンズ
の励磁量を制御するためにメモリに記憶されているテー
ブルを説明するための図である。[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is an apparatus configuration diagram for explaining an embodiment of the present invention,
FIG. 2 is a diagram showing a relationship between a sample irradiation current and a sample irradiation current diameter in a scanning electron microscope using a field emission electron gun, FIG. 3 is a diagram showing a relationship between a minimum sample irradiation electron beam diameter and an acceleration voltage, and FIG. FIG. 4 is a diagram for explaining a table stored in a memory for controlling the excitation amount of the electron lens based on the acceleration voltage and the extraction voltage.
第１図において１は針状陰極、２は第１陽極、３は第
２陽極、４は引出電源、５は加速電源、９は試料、10は
集束レンズ、11は対物レンズ、12はメモリ、13は電子レ
ンズ制御部である。レンズ制御部13はメモリ12からのデ
ータに基づいて集束レンズ10の励磁電流値を制御し、指
示された試料照射電流を実現できるように構成されてい
る。In FIG. 1, 1 is a needle cathode, 2 is a first anode, 3 is a second anode, 4 is an extraction power source, 5 is an acceleration power source, 9 is a sample, 10 is a focusing lens, 11 is an objective lens, 12 is a memory, Reference numeral 13 denotes an electronic lens control unit. The lens control unit 13 is configured to control the exciting current value of the focusing lens 10 based on the data from the memory 12 so as to realize the specified sample irradiation current.
先ず、電子顕微鏡の操作者により電源４から陰極１−
第１陽極２間に引出し電圧Ve、電源５から陰極１−第２
陽極３間に加速電圧Vaが印加される。ここで、該電圧値
の設定は数種類のVa値及びVe値の組合わせによるVa/Ve
比で設定され、該設定された電圧値は一定値に維持され
るように安定化制御されている。First, the operator of the electron microscope switches the power source 4 to the cathode 1-.
An extraction voltage Ve is applied between the first anode 2 and a cathode 1-second
An acceleration voltage Va is applied between the anodes 3. Here, the setting of the voltage value is based on a combination of several kinds of Va value and Ve value.
A ratio is set, and stabilization control is performed so that the set voltage value is maintained at a constant value.
前記引き出し電圧Ve,加速電圧Vaが設定されると、前
記引出し電圧Veによって陰極１から電子線が放出され
る。該陰極１から放出され第１陽極２を通過した電子線
は第２陽極３へ向けて加速されると共に、該２陽極３の
電子線通過孔を通過して集束レンズ10に入射する。そし
て、該電子線は該集束レンズ10によって集束されて対物
レンズ11に導入され、該対物レンズによって試料９上に
集束照射される。When the extraction voltage Ve and the acceleration voltage Va are set, an electron beam is emitted from the cathode 1 by the extraction voltage Ve. The electron beam emitted from the cathode 1 and passed through the first anode 2 is accelerated toward the second anode 3 and enters the focusing lens 10 through the electron beam passage hole of the second anode 3. Then, the electron beam is focused by the focusing lens 10 and introduced into the objective lens 11, and is focused and irradiated on the sample 9 by the objective lens.
さて、引出し電圧Veが一定値例えば、5KVに設定され
た場合について、加速電圧Vaをパラメータとして試料照
射電流Ipと試料照射電子線径Ｒの関係について測定した
結果、第２図に示すような関係があることが明らかとな
った。第２図において縦軸は試料照射電子線径、横軸は
試料照射電子線電流を表しており、曲線ａはVa＝1KVの
場合、曲線ｂはVa＝5KVの場合、曲線ｃはVa＝40KVの場
合を示している。図から明らかなように、試料照射電子
線電流を減少させても試料照射電子線径が減少しなくな
る点が存在する。各加速電圧における該領域の開始点Pa
〜Pcはビーム径が最も小さくなった場合に、照射電流が
最大となる点である。これらの点で表された条件はSN比
の良い高分解能な二次電子像が得られる最適な試料照射
条件に一致する。Now, when the extraction voltage Ve is set to a constant value, for example, 5 KV, the relationship between the sample irradiation current Ip and the sample irradiation electron beam diameter R is measured using the acceleration voltage Va as a parameter, and the relationship shown in FIG. 2 is obtained. It became clear that there was. In FIG. 2, the vertical axis represents the sample irradiation electron beam diameter, and the horizontal axis represents the sample irradiation electron beam current. The curve a is for Va = 1 KV, the curve b is for Va = 5 KV, and the curve c is Va = 40 KV. Is shown. As is apparent from the figure, there is a point where the diameter of the sample irradiation electron beam does not decrease even when the sample irradiation electron beam current is reduced. Starting point Pa of the region at each accelerating voltage
PPc is the point where the irradiation current is maximum when the beam diameter is smallest. The conditions expressed by these points correspond to the optimal sample irradiation conditions for obtaining a high-resolution secondary electron image with a good SN ratio.
なお、これらの点Ｐを種々の加速電圧について求める
ことにより、同図に点線で示すような曲線が描かれる。
そしてこの曲線について、加速電圧を横軸にとり試料照
射電子線電流を縦軸にとって表わすと、第３図に示すよ
うになる。By obtaining these points P for various acceleration voltages, a curve as shown by a dotted line is drawn in FIG.
When the acceleration voltage is plotted on the horizontal axis and the electron beam current for sample irradiation is plotted on the vertical axis, the curve is as shown in FIG.
メモリ12にはこの引出電圧Veが5KVの場合だけでな
く、Veを種々変えた夫々の場合に、加速電圧Vaの種々の
設定値に対して、試料照射電子線径を最小とし、その最
小径の状態で試料照射電子線電流値を最大にするために
必要な集束レンズ10の励磁電流値Ｄを表すテーブルが記
憶されている。これら各データは以下のようにして求め
られる。即ち、引出電圧をVei、加速電圧をVajで電界放
出型電子銃を稼動させている最中に、試料照射電流Ipを
変化させながら試料照射電流径Ｒを測定し、該試料照射
電子線径が変化しなくなる開始点における集束レンズ10
の励磁電流Dijを測定して記録することにより１データ
を得る。そして、加速電圧VajをVa1からVa2,Va3,…,Van
と変化させて上記測定を行ない夫々の場合の集束レンズ
10の励磁電流Dil〜Dinを求めることにより、一組のデー
タ（定電圧Vei時のデータ）を得ることができる。同様
の作業を引出電圧VeiをVe1からVe2,Ve3,…,Vemまで変化
させて全てのデータを得ることができる。このようにし
て得られたデータをテーブルとして格納したメモリ12の
内容を例示すれば、第４図のようになる。そこで、前記
電子レンズ制御部13は引出電源４及び加速電源５の出力
信号（電圧を表す信号）に基づいて、メモリ12内データ
を参照し、試料照射電子線径を最小且つ試料照射電子線
電流値を最大とするのに必要な前記集束レンズ10の励磁
量を表す信号を制御部13内に読出す。そして、該電子レ
ンズ制御部13は読出されたデータに基づいて、集束レン
ズ10の励磁量を制御し、試料照射電子線径を最小且つ試
料照射電子線電流値を最大の条件で電子線を試料に照射
するようにしている。In the memory 12, not only when the extraction voltage Ve is 5 KV, but also in each case where Ve is variously changed, the sample irradiation electron beam diameter is minimized with respect to various setting values of the acceleration voltage Va, and the minimum diameter is obtained. In this state, a table representing the exciting current value D of the focusing lens 10 necessary for maximizing the sample irradiation electron beam current value is stored. Each of these data is obtained as follows. That is, while operating the field emission electron gun with the extraction voltage at Ve i and the acceleration voltage at Va j , the sample irradiation current diameter R was measured while changing the sample irradiation current Ip, and the sample irradiation electron beam was measured. Focusing lens 10 at the starting point where the diameter does not change
Is measured and recorded to obtain one data. Then, the acceleration voltage Va j from Va 1 Va 2, Va 3, ..., Va n
Focusing lenses for each case
By obtaining the ten exciting currents Dil to Din, a set of data (data at a constant voltage Ve i ) can be obtained. Similar Ve 2 work the extraction voltage Ve i from Ve 1, Ve 3, ..., it is possible to obtain all the data is changed from Ve m. FIG. 4 shows an example of the contents of the memory 12 in which the data thus obtained is stored as a table. Therefore, the electron lens control unit 13 refers to the data in the memory 12 based on the output signals (signals representing the voltages) of the extraction power supply 4 and the acceleration power supply 5 and minimizes the sample irradiation electron beam diameter and the sample irradiation electron beam current. A signal indicating the amount of excitation of the focusing lens 10 necessary for maximizing the value is read into the control unit 13. Then, the electron lens control unit 13 controls the excitation amount of the focusing lens 10 based on the read data, and converts the electron beam to the sample under the condition that the sample irradiation electron beam diameter is minimum and the sample irradiation electron beam current value is maximum. To be irradiated.
上述のような構成において、電子顕微鏡の操作者によ
り例えばVe＝Ve2、Va＝Va3に設定され、電子銃が稼動状
態に入ったとする。制御部13は引出電源４及び加速電源
５からの出力信号に基づいて第４図に示すようなメモリ
に記憶されているテーブル内の（Ve2,Va3）に対応する
アドレスを指定してデータD23を読み出す。そして、前
記制御部13は該読出されたデータに基づいて集束レンズ
11の励磁電流値を制御して試料照射電子線径を最小と
し、その最小径の状態で試料照射電子線電流値を最大と
する条件に設定する。従って、電子線は試料照射電子線
径を最小且つ試料照射電子線電流値を最大の条件で試料
に照射される。また、電子銃の加速電圧をVa1に変化さ
せた場合には、テーブル内の（Ve2,Va1）に対応するア
ドレスが指定されてデータD21が読み出され、該データ
に基づいて集束レンズ10の励磁電流が変えられるため、
試料には常に試料照射電子線径を最小且つ試料照射電子
線電流値を最大の条件で電子線が照射される。そのた
め、常に高分解能な二次電子像を得ることができる。In the configuration as described above, it is assumed that the operator of the electron microscope sets, for example, Ve = Ve 2 and Va = Va 3 and the electron gun enters the operating state. The control unit 13 specifies an address corresponding to (Ve 2 , Va 3 ) in a table stored in a memory as shown in FIG. 4 based on the output signals from the extraction power supply 4 and the acceleration power supply 5 and stores the data. Read D23. The control unit 13 controls the focusing lens based on the read data.
The excitation current value of 11 is controlled to minimize the sample irradiation electron beam diameter, and a condition is set to maximize the sample irradiation electron beam current value in the state of the minimum diameter. Accordingly, the sample is irradiated with the electron beam under the condition that the sample irradiation electron beam diameter is minimum and the sample irradiation electron beam current value is maximum. Further, when the accelerating voltage of the electron gun is changed to Va 1 is addressed is designated corresponding to in the table (Ve 2, Va 1) data D21 is read, the focusing lens based on the data Because 10 exciting currents can be changed,
The sample is always irradiated with an electron beam under the condition that the sample irradiation electron beam diameter is minimum and the sample irradiation electron beam current value is maximum. Therefore, a high-resolution secondary electron image can always be obtained.
［発明の効果］ 以上の説明から明らかなように、本発明によれば、第
１陽極へ印加される電圧を表す信号と第２陽極へ印加さ
れる電圧を表す信号に基づき、試料照射電子線径が最小
且つその最小径の状態で試料照射電子線電流値が最大と
なるように集束レンズを制御するので、熟練しない操作
者でも試料照射電子線径を最小にした上で最大の試料照
射電子線電流値の電子線を簡単に試料に照射できる電子
線装置を提供することができる。したがって、この装置
を走査電子顕微鏡に適用した場合には、熟練しない操作
者でも高分解能で高画質の走査電子顕微鏡像を得ること
ができる。[Effects of the Invention] As is apparent from the above description, according to the present invention, the sample irradiation electron beam is based on the signal representing the voltage applied to the first anode and the signal representing the voltage applied to the second anode. Since the focusing lens is controlled so that the sample irradiation electron beam current value is maximized in a state where the diameter is minimum and the minimum diameter, even an unskilled operator can minimize the sample irradiation electron beam diameter and increase the maximum sample irradiation electron beam. An electron beam apparatus that can easily irradiate a sample with an electron beam having a line current value can be provided. Therefore, when this apparatus is applied to a scanning electron microscope, even an unskilled operator can obtain a high-resolution and high-quality scanning electron microscope image.
第１図は本発明の一実施例を説明するための装置構成
図、第２図は電界放出型電子銃を用いた走査電子顕微鏡
における試料照射電流と試料照射電流径の関係を示す
図、第３図は最小試料照射電子線径と加速電圧の関係を
示す図、第４図は加速電圧と引出電圧に基づいて電子レ
ンズの励磁量を制御する際に用いられるテーブルを説明
するための図である。 1:針状陰極、2:第１陽極 3:第２陽極、4:引出電源 5:加速電源、9:試料 10:集束レンズ、11:対物レンズ 12:メモリ、13:電子レンズ制御部FIG. 1 is a diagram showing the configuration of an apparatus for explaining an embodiment of the present invention. FIG. 2 is a diagram showing the relationship between the sample irradiation current and the sample irradiation current diameter in a scanning electron microscope using a field emission electron gun. FIG. 3 is a diagram showing the relationship between the minimum sample irradiation electron beam diameter and the acceleration voltage, and FIG. 4 is a diagram for explaining a table used when controlling the excitation amount of the electron lens based on the acceleration voltage and the extraction voltage. is there. 1: Needle-shaped cathode, 2: First anode 3: Second anode, 4: Extraction power supply 5: Acceleration power supply, 9: Sample 10: Focusing lens, 11: Objective lens 12: Memory, 13: Electronic lens controller
Claims (1)
るための第１陽極と、陰極から放出され第１陽極を通過
する電子線を加速するための第２陽極と、該第２陽極を
通過して電子線を集束して試料上に照射するための集束
レンズと対物レンズとを備えた電子線装置において、前
記第１陽極へ印加される電圧を表す信号と前記第２陽極
へ印加される電圧を表す信号に基づいて試料照射電子線
径を最小且つその最小径の状態で試料照射電子線電流値
を最大とするのに必要な前記集束レンズの励磁量を表す
信号を発生するための手段と、該発生した信号に基づい
て前記集束レンズの励磁を制御する手段とを設けたこと
を特徴とする電子線装置。A cathode; a first anode for forming an extraction electric field between the cathode; a second anode for accelerating an electron beam emitted from the cathode and passing through the first anode; In an electron beam apparatus provided with a focusing lens and an objective lens for focusing an electron beam through a second anode and irradiating the sample on a sample, a signal representing a voltage applied to the first anode and the second anode A signal representing the excitation amount of the focusing lens required to maximize the sample irradiation electron beam current value in a state where the diameter of the sample irradiation electron beam is minimum and at the minimum diameter is generated based on the signal representing the voltage applied to the And a means for controlling the excitation of the focusing lens based on the generated signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63285273A JP2636381B2 (en) | 1988-11-11 | 1988-11-11 | Electron beam equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63285273A JP2636381B2 (en) | 1988-11-11 | 1988-11-11 | Electron beam equipment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02132741A JPH02132741A (en) | 1990-05-22 |
| JP2636381B2 true JP2636381B2 (en) | 1997-07-30 |
Family
ID=17689372
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63285273A Expired - Fee Related JP2636381B2 (en) | 1988-11-11 | 1988-11-11 | Electron beam equipment |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2636381B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2919170B2 (en) * | 1992-03-19 | 1999-07-12 | 株式会社日立製作所 | Scanning electron microscope |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58188041A (en) * | 1982-04-27 | 1983-11-02 | Shimadzu Corp | Probe diameter setting method of charged particle rays |
| JPS61114453A (en) * | 1984-11-08 | 1986-06-02 | Jeol Ltd | Charged particle ray device |
| JP2705056B2 (en) * | 1986-12-26 | 1998-01-26 | 株式会社島津製作所 | Autofocus device |
-
1988
- 1988-11-11 JP JP63285273A patent/JP2636381B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02132741A (en) | 1990-05-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |