JPH0492346A - Electric field discharge type electron gun - Google Patents
Electric field discharge type electron gunInfo
- Publication number
- JPH0492346A JPH0492346A JP2210705A JP21070590A JPH0492346A JP H0492346 A JPH0492346 A JP H0492346A JP 2210705 A JP2210705 A JP 2210705A JP 21070590 A JP21070590 A JP 21070590A JP H0492346 A JPH0492346 A JP H0492346A
- Authority
- JP
- Japan
- Prior art keywords
- emitter
- cathode
- electron gun
- control circuit
- extraction
- 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
- 230000005684 electric field Effects 0.000 title description 4
- 238000010438 heat treatment Methods 0.000 claims abstract description 24
- 238000000605 extraction Methods 0.000 claims description 38
- 230000001133 acceleration Effects 0.000 claims description 16
- 238000001514 detection method Methods 0.000 claims description 6
- 230000004075 alteration Effects 0.000 abstract description 5
- 238000011010 flushing procedure Methods 0.000 description 10
- 238000013459 approach Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
Abstract
Description
【発明の詳細な説明】
［産業上の利用分野］
本発明は、収差の少ない安定した電子源を簡単に実現し
た電界放出型電子銃に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a field emission electron gun that easily realizes a stable electron source with few aberrations.
［従来の技術］
電界放出型電子銃では、引出し電極と陰極との間に引出
し電圧を印加する事により、陰極の先端部に強電界を発
生させて、該陰極先端部から電子を放出させ、更に、該
陰極に加速電圧を印加して該放出電子を加速する様にし
ている。[Prior Art] In a field emission electron gun, an extraction voltage is applied between an extraction electrode and a cathode to generate a strong electric field at the tip of the cathode, causing electrons to be emitted from the tip of the cathode. Further, an accelerating voltage is applied to the cathode to accelerate the emitted electrons.
［発明が解決しようしする課題］
さて、同じ放出電子を得るのに、引出し電圧を通常の場
合より下げる事が出来れば、低エネルギー電界放出電子
源が実現出来るので、低加速で放出電子を加速する場合
、引出し電極と加速電極の間での減速が少なくて済み、
その為に、収差の少ない良質の電子源を得る事が可能と
なる。[Problem to be solved by the invention] Now, if the extraction voltage can be lowered than usual to obtain the same emitted electrons, a low-energy field emission electron source can be realized, so the emitted electrons can be accelerated at a low acceleration. In this case, there is less deceleration between the extraction electrode and the acceleration electrode,
Therefore, it is possible to obtain a high-quality electron source with few aberrations.
この様な電子源において、エミッション電流が変化する
場合に、エミッタ先端を僅かに移動させる事によりエミ
ッタ先端の電場を顕著に変化させる事が出来、その結果
、エミ・ソション電流を安定させる事が出来る。In such an electron source, when the emission current changes, the electric field at the emitter tip can be significantly changed by slightly moving the emitter tip, and as a result, the emitter current can be stabilized. .
この様な低エネルギー電界放出電子源が実現する為に、
例えば、機械的に陰極若しくは引出し電極を移動可能に
成して、互いに近付く様にしたり、ピエゾ素子等を陰極
若しくは引出し電極に取付けて互いに近付く様にしたり
出来る。しかし、何れも構造が複雑となる。操作が面倒
である。費用も掛かる。フラッシング時、この様な素子
からガスが出る等、問題が多い。In order to realize such a low energy field emission electron source,
For example, the cathodes or extraction electrodes can be made mechanically movable so that they approach each other, or piezo elements or the like can be attached to the cathodes or extraction electrodes so that they approach each other. However, both have complicated structures. It is cumbersome to operate. It also costs money. There are many problems such as gas coming out from such elements during flushing.
本発明はこの様な収差の少ない安定した電子源を簡単に
実現する新規な電界放出型電子銃を提供する事を目的と
する。An object of the present invention is to provide a novel field emission type electron gun that can easily realize a stable electron source with little aberration.
［課題を解決するための手段］
その為に本発明の電界放出型電子銃は、エミッタを支持
した陰極、引出し電極、加速電極、前記陰極と引出し電
極の間に引出し電圧を印加する引出し電圧源、前記陰極
と加速電極の間に加速電圧を印加する加速電圧源、前記
引出し電圧源及び加速電圧源の動作中に前記陰極を、該
陰極から熱電子が放出されない程度に加熱する手段、及
びエミッション電流検出手段を備え、該検出手段からの
信号により前記加熱手段を制御する様に成した。[Means for Solving the Problems] To achieve this, the field emission electron gun of the present invention includes a cathode that supports an emitter, an extraction electrode, an accelerating electrode, and an extraction voltage source that applies an extraction voltage between the cathode and the extraction electrode. , an accelerating voltage source that applies an accelerating voltage between the cathode and the accelerating electrode, means for heating the cathode to an extent that thermionic electrons are not emitted from the cathode during operation of the extraction voltage source and the accelerating voltage source, and an emission source. A current detection means is provided, and the heating means is controlled by a signal from the detection means.
［実施例コ
第１図は本発明の一実施例として示した電界放出型電子
銃の概略図である。[Embodiment] FIG. 1 is a schematic diagram of a field emission type electron gun shown as an embodiment of the present invention.
図中１はエミッタ、２は陰極フィラメント、３は引出し
電極、４は加速電極、５は引出し電圧源、６は加速電圧
源、７は引出し電圧源コントロール回路、８は加速電圧
源コントロール回路、９は加熱電源、１０は加熱電源コ
ントロール回路、１１はフラッシングコントロール回路
、１２はスイッチコントロール回路、１３はスイッチで
ある。１４はエミッション電流検出手段である。In the figure, 1 is an emitter, 2 is a cathode filament, 3 is an extraction electrode, 4 is an acceleration electrode, 5 is an extraction voltage source, 6 is an acceleration voltage source, 7 is an extraction voltage source control circuit, 8 is an acceleration voltage source control circuit, 9 10 is a heating power supply, 11 is a flushing control circuit, 12 is a switch control circuit, and 13 is a switch. 14 is an emission current detection means.
この様な電子銃は、例えば、電子顕微鏡等の電子ビーム
装置の電子銃室に取り付けられ、該電子銃室内が極めて
低い圧力（例えば、１Ｏ−８ｔｏｒｒ以下）に排気され
る。Such an electron gun is attached to, for example, an electron gun chamber of an electron beam device such as an electron microscope, and the inside of the electron gun chamber is evacuated to an extremely low pressure (for example, 10-8 torr or less).
さて、前記エミッタの先端部に強電界を発生させて、該
エミッタ先端部から電子を放出させる前に、フラッシン
グコントロール回路１１からスイッチングコントロール
回路１２及び加熱電源コントロール回路１０にフラッシ
ング指令信号を送る。Now, before a strong electric field is generated at the tip of the emitter and electrons are emitted from the tip of the emitter, a flushing command signal is sent from the flushing control circuit 11 to the switching control circuit 12 and the heating power supply control circuit 10.
該信号により前記スイッチングコントロール回路１２は
スイッチ１３をオンの状態にする。また、前記加熱電源
コントロール回路１０は加熱電源９に指令を送り、該加
熱電源から前記陰極フィラメント２にエミッタ１をフラ
ッシングする電流を流す様に、該加熱電源をコントロー
ルする。該フラッシング電流により、前記エミッタは２
０００６Ｃ程度に加熱され、該エミッタはフラッシング
される。該フラッシング終了後、前記フラッシングコン
トロール回路１１からスイッチングコントロール回路１
２及び加熱電源コントロール回路１０にフラッシング停
止信号を送り、前記スイッチ１３をオフの状態にし、且
つ前記加熱電源９からのフラッシング電流の供給を停止
させる。次に、該フラッシングにより発生する脱ガス等
を排気系（図示せず）により排気した後、引出し電圧源
コントロール回路７からスイッチングコントロール回路
１２．加熱電源コントロール回路１０及び引出し電圧源
５に引出し電圧印加指令信号を送り、且つ加速電圧源コ
ントロール回路８から加速電圧源６に加速電圧印加指令
信号を送る。該各信号により前記スイッチングコントロ
ール回路１２はスイッチ１３をオンの状態にし、前記加
熱電源コントロール回路１０は加熱電源９に指令を送り
、該加熱電源から前記陰極フィラメント２に、該エミッ
タから熱電子が放出されない程度の電流を流す様に、該
加熱電源をコントロールする。又、前記引出し電圧印加
指令信号により、前記引出し電圧源５は前記陰極フィラ
メント２と引出し電極３との間に引出し電圧を印加し、
前記加速電圧印加指令信号により、前記加速電圧源６は
前記陰極フィラメント２と加速電極３との間に加速電圧
を印加する。In response to this signal, the switching control circuit 12 turns on the switch 13. Further, the heating power source control circuit 10 sends a command to the heating power source 9, and controls the heating power source so that a current for flushing the emitter 1 flows from the heating power source to the cathode filament 2. The flashing current causes the emitter to
The emitter is heated to about 0.0006C and flushed. After the flushing is completed, the switching control circuit 1 is transferred from the flushing control circuit 11 to the switching control circuit 1.
2 and the heating power supply control circuit 10, the switch 13 is turned off, and the supply of flushing current from the heating power supply 9 is stopped. Next, after the degas generated by the flushing is exhausted by an exhaust system (not shown), the output voltage source control circuit 7 is transferred to the switching control circuit 12. An extraction voltage application command signal is sent to the heating power supply control circuit 10 and the extraction voltage source 5, and an acceleration voltage application command signal is sent from the acceleration voltage source control circuit 8 to the acceleration voltage source 6. According to each signal, the switching control circuit 12 turns on the switch 13, the heating power supply control circuit 10 sends a command to the heating power supply 9, and thermionic electrons are emitted from the heating power supply to the cathode filament 2 from the emitter. The heating power source is controlled so that the current flows to an extent that does not cause the heating to occur. Further, in response to the extraction voltage application command signal, the extraction voltage source 5 applies an extraction voltage between the cathode filament 2 and the extraction electrode 3,
In response to the acceleration voltage application command signal, the acceleration voltage source 6 applies an acceleration voltage between the cathode filament 2 and the acceleration electrode 3.
而して、前記エミッタ１に、前記加熱電源９からスイッ
チ１３を介して、該エミッタから熱電子が放出されない
程度の電流が流されるので、該エミッタは大略１０００
０Ｃ以下に加熱される。ここで、若し、エミッタから熱
電子が放出される様な電流が流されると、エミッタ近傍
の圧力が悪化（即ち、圧力が上昇）して、該電子銃から
得られるビームの密度分布の一様性が悪くなる。さて、
該加熱により、エミッタ１は、熱膨脹して、引出し電極
３に近づく。この際、前記フィラメントの２の端部から
エミッタの先端までの長さを、例えば、１０ｍｍとし、
該フィラメントの線膨張率を５Ｘ１０−６とすれば、該
エミッタ先端の引出し電極側への線膨脹により、前記先
端は５０μｍ引出し電極３に近づき、エミッション電流
が増加する。Then, a current of such an extent that thermionic electrons are not emitted from the emitter is passed through the emitter 1 from the heating power source 9 via the switch 13, so that the emitter has a current of about 1000
Heated to below 0C. If a current that causes thermionic electrons to be emitted from the emitter is applied, the pressure near the emitter will worsen (that is, the pressure will increase), and the density distribution of the beam obtained from the electron gun will change. His condition worsens. Now,
Due to the heating, the emitter 1 thermally expands and approaches the extraction electrode 3. At this time, the length from the second end of the filament to the tip of the emitter is, for example, 10 mm,
If the coefficient of linear expansion of the filament is 5.times.10@-6, the linear expansion of the emitter tip toward the extraction electrode causes the tip to approach the extraction electrode 3 by 50 .mu.m, and the emission current increases.
但し、エミッタ先端と引出し電極の距離が、エミッショ
ン電流の値に顕著に関係するのは、大略２００μｍ以下
なので、予め、エミッタ先端と引出し電極の距離が、例
えば、２００μｍに成る様に、前記フィラメント２と引
出し電極の位置が調整されている。第２図は、エミッタ
先端と引出し電極の距Ｍｄと、エミッション電流の関係
を示したものである。該図に於いて、＋側はエミッタ先
端が引出し電極３より上方にある場合、−側はエミッタ
先端が引出し電極３より下方にある場合である。However, since the distance between the emitter tip and the extraction electrode is approximately 200 μm or less, which is significantly related to the value of the emission current, the filament 2 is prepared in advance so that the distance between the emitter tip and the extraction electrode is, for example, 200 μm. and the position of the extraction electrode has been adjusted. FIG. 2 shows the relationship between the distance Md between the emitter tip and the extraction electrode and the emission current. In this figure, the + side is when the emitter tip is above the extraction electrode 3, and the - side is when the emitter tip is below the extraction electrode 3.
尚、前記エミッタの先端と引出し電極３との距離の調整
は、エミッション電流検出手段１４からの信号に基づい
て前記加熱電源コントロール回路１０によって行なわれ
る。例えば、エミッタ先端が＋側にある場合に、エミッ
ション電流が減少傾向にある時、徐々にエミッタ１を加
熱して、該エミッタ１を引出し電極３に徐々に近付け、
エミッション電流が減少しない様に制御する事が出来る
。The distance between the tip of the emitter and the extraction electrode 3 is adjusted by the heating power supply control circuit 10 based on a signal from the emission current detection means 14. For example, when the emitter tip is on the + side and the emission current tends to decrease, the emitter 1 is gradually heated and the emitter 1 is gradually brought closer to the extraction electrode 3;
It is possible to control the emission current so that it does not decrease.
［発明の効果］
本発明は、冷陰極の状態で引出し電圧源及び加速電圧源
を動作中に前記陰極を、該陰極から熱電子が放出されな
い程度に加熱し、該陰極に支持されたエミッタ先端と引
出し電極との距離を小さく制御出来る様に成したもので
、従来のものに比べ、構造が簡単である。操作が簡単で
ある。費用が掛からない。フラッシング時に余分なガス
が出る心配がない等、効果が大きい。[Effects of the Invention] The present invention heats the cathode to such an extent that thermoelectrons are not emitted from the cathode while operating an extraction voltage source and an accelerating voltage source in a cold cathode state, and heats the emitter tip supported by the cathode. It is designed so that the distance between the electrode and the extraction electrode can be controlled small, and the structure is simpler than the conventional one. Easy to operate. It costs nothing. It is very effective as there is no need to worry about excess gas being released during flushing.
第１図は本発明の一実施例として示した電界放出型電子
銃の概略図、第２図は、該電子銃の動作の説明を補足す
る為に用いた図である。FIG. 1 is a schematic diagram of a field emission type electron gun shown as an embodiment of the present invention, and FIG. 2 is a diagram used to supplement the explanation of the operation of the electron gun.
Claims (1)
陰極と引出し電極の間に引出し電圧を印加する引出し電
圧源、前記陰極と加速電極の間に加速電圧を印加する加
速電圧源、前記引出し電圧源及び加速電圧源の動作中に
前記陰極を、該陰極から熱電子が放出されない程度の温
度に加熱する手段、及びエミッション電流検出手段を備
え、該検出手段からの信号により前記加熱手段を制御す
る様に成した電界放出型電子銃。A cathode supporting an emitter, an extraction electrode, an acceleration electrode, an extraction voltage source that applies an extraction voltage between the cathode and the extraction electrode, an acceleration voltage source that applies an acceleration voltage between the cathode and the acceleration electrode, and the extraction voltage source and means for heating the cathode to a temperature at which thermoelectrons are not emitted from the cathode during operation of the accelerating voltage source, and an emission current detection means, and the heating means is controlled by a signal from the detection means. A field emission type electron gun.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2210705A JPH0492346A (en) | 1990-08-08 | 1990-08-08 | Electric field discharge type electron gun |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2210705A JPH0492346A (en) | 1990-08-08 | 1990-08-08 | Electric field discharge type electron gun |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0492346A true JPH0492346A (en) | 1992-03-25 |
Family
ID=16593738
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2210705A Pending JPH0492346A (en) | 1990-08-08 | 1990-08-08 | Electric field discharge type electron gun |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0492346A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008311174A (en) * | 2007-06-18 | 2008-12-25 | Jfe Engineering Kk | Electron beam generator and its control method |
| JP2018045905A (en) * | 2016-09-15 | 2018-03-22 | 日新イオン機器株式会社 | Ion source |
-
1990
- 1990-08-08 JP JP2210705A patent/JPH0492346A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008311174A (en) * | 2007-06-18 | 2008-12-25 | Jfe Engineering Kk | Electron beam generator and its control method |
| JP2018045905A (en) * | 2016-09-15 | 2018-03-22 | 日新イオン機器株式会社 | Ion source |
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