JP3397616B2 - Thermal field emission electron gun and method of manufacturing emitter for thermal field emission electron gun - Google Patents
Thermal field emission electron gun and method of manufacturing emitter for thermal field emission electron gunInfo
- Publication number
- JP3397616B2 JP3397616B2 JP02870797A JP2870797A JP3397616B2 JP 3397616 B2 JP3397616 B2 JP 3397616B2 JP 02870797 A JP02870797 A JP 02870797A JP 2870797 A JP2870797 A JP 2870797A JP 3397616 B2 JP3397616 B2 JP 3397616B2
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- Prior art keywords
- emitter
- tip
- electron
- thermal field
- electron gun
- Prior art date
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Links
- 238000004519 manufacturing process Methods 0.000 title claims description 8
- 230000005684 electric field Effects 0.000 claims description 39
- 238000000605 extraction Methods 0.000 claims description 26
- 238000010894 electron beam technology Methods 0.000 claims description 17
- 239000013078 crystal Substances 0.000 claims description 11
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 11
- 229910052721 tungsten Inorganic materials 0.000 claims description 11
- 239000010937 tungsten Substances 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 10
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 7
- 229910052760 oxygen Inorganic materials 0.000 claims description 7
- 239000001301 oxygen Substances 0.000 claims description 7
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 4
- 229910052726 zirconium Inorganic materials 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 3
- 238000009826 distribution Methods 0.000 description 20
- 229910052751 metal Inorganic materials 0.000 description 9
- 239000002184 metal Substances 0.000 description 9
- 230000008569 process Effects 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 238000005036 potential barrier Methods 0.000 description 6
- 239000000523 sample Substances 0.000 description 5
- 230000004075 alteration Effects 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- 241000723368 Conium Species 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000003574 free electron Substances 0.000 description 1
- 230000014509 gene expression Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000005381 potential energy Methods 0.000 description 1
- VSZWPYCFIRKVQL-UHFFFAOYSA-N selanylidenegallium;selenium Chemical compound [Se].[Se]=[Ga].[Se]=[Ga] VSZWPYCFIRKVQL-UHFFFAOYSA-N 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 230000005641 tunneling Effects 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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- Cold Cathode And The Manufacture (AREA)
- Electron Sources, Ion Sources (AREA)
- Solid Thermionic Cathode (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、走査電子顕微鏡等
の電子ビーム装置に用いられる熱電界放出電子銃および
熱電界放出電子銃用エミッタの製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal field emission electron gun used in an electron beam apparatus such as a scanning electron microscope and a method for manufacturing an emitter for a thermal field emission electron gun.
【０００２】[0002]
【従来の技術】近年、走査電子顕微鏡等の電子ビーム装
置では、高い輝度の熱電界放出電子銃が使用されてい
る。この電子銃では、タングステン等のエミッタを高温
に加熱すると共に、エミッタと引出電極との間に数ｋＶ
の引出電圧を印加するようにしている。2. Description of the Related Art In recent years, high-brightness thermal field emission electron guns have been used in electron beam devices such as scanning electron microscopes. In this electron gun, an emitter such as tungsten is heated to a high temperature, and several kV is placed between the emitter and the extraction electrode.
Is applied.
【０００３】このような電子銃では、エミッタ先端での
電界強度を高め、輝度の高い熱電界放出電子をエミッタ
先端から放出させるために、先端の半径が小さなエミッ
タが使用されている。例えば、タングステン製エミッタ
では、０．４〜０．５μｍ程度の半径とされている。In such an electron gun, an emitter having a small tip radius is used in order to increase the electric field strength at the tip of the emitter and emit thermal field emission electrons with high brightness from the tip of the emitter. For example, a tungsten emitter has a radius of about 0.4 to 0.5 μm.
【０００４】図１はエミッタ先端の電界強度Ｆ［Ｖ／ｃ
ｍ］と、放出電子のエネルギ分布幅（エネルギ分布の半
値幅ΔＥ［ｅＶ］）の関係を示している。この図から明
らかなように、電界強度Ｆを高めると、熱電界放出電子
のエネルギ分布幅（エネルギ分布の半値幅ΔＥ［ｅ
Ｖ］）が大きくなる。FIG. 1 shows the electric field strength F [V / c at the tip of the emitter.
m] and the energy distribution width of the emitted electrons (half-width ΔE [eV] of energy distribution). As is clear from this figure, when the electric field strength F is increased, the energy distribution width of the thermal field emission electrons (half-width ΔE [e
V]) becomes large.
【０００５】このような現象のために、電界強度を高め
て輝度を増すと、走査電子顕微鏡等では、試料に照射さ
れる電子ビームの径が大きくなり、得られる像の分解能
が低下してしまう。Due to such a phenomenon, when the electric field strength is increased to increase the brightness, the diameter of the electron beam with which the sample is irradiated becomes large in a scanning electron microscope or the like, and the resolution of the obtained image deteriorates. .
【０００６】また、エミッタの先端の半径が小さいと、
エミッタ先端部に形成されるファセットの結晶面が小さ
くなり、そのため、エミッタ先端での原子が不安定とな
る。すなわち、エミッタ先端部での原子移動は、温度や
電界強度に依存するが、エミッタ先端の半径が小さいた
めに、原子が安定する条件幅が狭く、原子の移動により
エミッタ先端の形状が変動してしまう。そのため、熱電
界放出電子の放出条件が変動し、エミッション電流が不
安定となる。If the radius of the tip of the emitter is small,
The facet crystal planes formed at the emitter tip become smaller, which makes the atoms at the emitter tip unstable. That is, although the movement of atoms at the tip of the emitter depends on the temperature and the electric field strength, since the radius of the tip of the emitter is small, the condition width for stabilizing the atoms is narrow, and the shape of the tip of the emitter changes due to the movement of the atoms. I will end up. Therefore, the emission conditions of thermal field emission electrons change, and the emission current becomes unstable.
【０００７】ところで、最近、熱電界放出電子銃におい
て、先端部の半径が２μｍ以上のエミッタを使用した場
合、エミッタ先端半径ｒが大きいと、電界強度Ｆを小さ
くできることが確かめられている。この結果、図１から
明らかなように、電界強度Ｆが小さくできるので、この
電子銃では、熱電界放出電子のエネルギ分布幅を小さく
できる。したがって、このような先端半径の大きなエミ
ッタを使用することで、先端半径の小さなエミッタが有
する各問題が解決される。By the way, recently, in a thermal field emission electron gun, when an emitter having a tip radius of 2 μm or more is used, it has been confirmed that the electric field strength F can be reduced when the emitter tip radius r is large. As a result, as is apparent from FIG. 1, the electric field strength F can be made small, so that in this electron gun, the energy distribution width of the thermal field emission electrons can be made small. Therefore, by using such an emitter having a large tip radius, the problems of the emitter having a small tip radius are solved.
【０００８】[0008]
【発明が解決しようとする課題】図２に従来の熱電界放
出電子銃の、特にエミッタ先端形状を示す。図２におい
て、（ａ）はエミッタ１の先端部位を真横から見た図、
（ｂ）はエミッタ先端部位を少し傾斜させて見た図であ
る。なお、このようなエミッタは、例えば、米国特許第
４，５８８，９２８号に開示されている。FIG. 2 shows a conventional thermal field emission electron gun, particularly the shape of the tip of an emitter. In FIG. 2, (a) is a view of the tip portion of the emitter 1 viewed from the side,
(B) is a view of the tip of the emitter with a slight inclination. Note that such an emitter is disclosed in, for example, U.S. Pat. No. 4,588,928.
【０００９】図２（ａ）に示すように、タングステン単
結晶針よりなるエミッタ１の先端部には、平坦な電子放
出面２が形成されている。この平坦電子放出面２の平坦
電子放出面半径ｂとエミッタ先端半径ｒとの比（ｂ／
ｒ）は、ほぼ０．３となる。この点については、文献Ap
plicstion of Surfaces Science 8(1981) 「RECENT PRO
GRESS IN THERMAL FIELD ELECTRON SOURCE PERFORMANC
E」に報告されている。[0009] As shown in FIG. 2 (a), the tip of the emitter 1 made of Tan grayed Sten single crystal needles are formed flat electron emission surface 2. The ratio of the flat electron emission surface radius b of the flat electron emission surface 2 to the emitter tip radius r (b /
r) is approximately 0.3. In this regard, reference Ap
plicstion of Surfaces Science 8 (1981) `` RECENT PRO
GRESS IN THERMAL FIELD ELECTRON SOURCE PERFORMANC
E ".
【００１０】しかし、前記電子放出面２が形成されるの
は、前記した米国特許や文献に記載されている例のよう
に、エミッタの先端半径ｒがほぼ０．５μｍの場合に、
エミッタ先端部位にほぼ２×１０7 （Ｖ／ｃｍ）〜３×
１０7 （Ｖ／ｃｍ）の電界がかけられているときであ
る。この条件において、エミッタから放出される電子ビ
ームのエネルギ分布の半値幅ΔＥ（ｅＶ）は、図１に示
すようにほぼ０．８ｅＶ〜１．０ｅＶとなる。However, the electron emission surface 2 is formed when the tip radius r of the emitter is approximately 0.5 μm, as in the examples described in the above-mentioned US patents and literatures.
Almost 2 × 10 7 (V / cm) to 3 × at the tip of the emitter
It is when an electric field of 10 7 (V / cm) is applied. Under this condition, the full width at half maximum ΔE (eV) of the energy distribution of the electron beam emitted from the emitter is approximately 0.8 eV to 1.0 eV as shown in FIG.
【００１１】図３は、エミッタ先端付近のエネルギ図で
ある。この図において、電子放出面をｘ軸に垂直な平面
と考え、ｘ＝０を金属の表面とする。なお、図中Ｅ
F は、フェルミレベル、φｗは仕事関数、−Ｗｏは金属
中における電子の実効的なポテンシャルエネルギであ
る。FIG. 3 is an energy diagram near the tip of the emitter. In this figure, the electron emission surface is considered as a plane perpendicular to the x axis, and x = 0 is the surface of the metal. In addition, E in the figure
F is the Fermi level, φw is the work function, and −Wo is the effective potential energy of electrons in the metal.
【００１２】この金属表面（ｘ＝０）に電界が印加され
ると、その近傍にポテンシャル障壁Ｖ（ｘ）が発生す
る。また、金属が加熱されると、ポテンシャル障壁の頂
上Ｖｍ以上のｘ方向成分のエネルギを有する金属自由電
子は、この頂上Ｖｍを乗り越えて金属外に放出される。
このような現象はショットキーエミッションと呼ばれて
いる。When an electric field is applied to this metal surface (x = 0), a potential barrier V (x) is generated in the vicinity thereof. Further, when the metal is heated, metal free electrons having energy in the x direction component equal to or higher than the peak Vm of the potential barrier get over the peak Vm and are emitted outside the metal.
Such a phenomenon is called Schottky emission.
【００１３】この際、印加される電界が十分に大きい
と、トンネル効果により金属内電子は、ポテンシャル障
壁Ｖ（ｘ）を乗り越えることなく、直接障壁を透過して
金属外に脱出できる。この現象は、金属の温度が比較的
低くても起こり、温度が室温程度の比較的低い場合をコ
ールドエミッション、温度が例えば、１８００Ｋ程度の
比較的高い場合をサーマルフィールド（ＴＦ）エミッシ
ョンと称している。At this time, if the applied electric field is sufficiently large, the electrons in the metal can directly pass through the potential barrier V (x) and escape to the outside of the metal without tunneling over the potential barrier V (x). This phenomenon occurs even when the temperature of the metal is relatively low, and when the temperature is relatively low around room temperature, it is called cold emission, and when the temperature is relatively high around 1800 K, for example, is called thermal field (TF) emission. .
【００１４】熱電界放出電子銃においては、前記した２
つの電子放出プロセスがあり、ＴＦエミッションはその
２つのプロセスを混在させている。ＴＦエミッション
は、エミッタ温度が、例えば、１８００Ｋの場合、エミ
ッタ先端での電界強度が１．０×１０7 Ｖ／ｃｍ以上に
なると、その混在の絶対量が顕著になり、図１に示すよ
うに、電界強度Ｆが高くなるにしたがって、放出電子の
エネルギ分布幅（エネルギ分布の半値幅ΔＥ）も高くな
る。In the thermal field emission electron gun, the above-mentioned 2
There are two electron emission processes, and TF emission mixes the two processes. In the TF emission, when the emitter temperature is, for example, 1800K, when the electric field strength at the tip of the emitter becomes 1.0 × 10 7 V / cm or more, the absolute amount of the mixture becomes remarkable, and as shown in FIG. As the electric field strength F increases, the energy distribution width of emitted electrons (the half-value width ΔE of the energy distribution) also increases.
【００１５】さて、公知である電子顕微鏡の一つの性能
を示す色収差による電子ビームのプローブ系ｄC は、
ｄC ＝ＣC α（ΔＥ／Ｖ）
で表される。ここで、ＣC は最終段レンズの色収差係
数、αは電子の試料面への入射角、Ｖは電子の平均エネ
ルギを示す。この式から、ΔＥが大きくなると、色収差
による電子プローブ系ｄC が大きくなり、電子顕微鏡の
分解能を劣化させてしまう。Now, the probe system d C of the electron beam due to chromatic aberration showing one performance of the known electron microscope is represented by d C = C C α (ΔE / V). Here, C C is the chromatic aberration coefficient of the final lens, α is the angle of incidence of the electrons on the sample surface, and V is the average energy of the electrons. From this equation, when ΔE becomes large, the electron probe system d C due to chromatic aberration becomes large and the resolution of the electron microscope deteriorates.
【００１６】このように、従来の平坦電子放出面２を持
ち、エミッタ半径がほぼ０．５μｍであるエミッタで
は、エミッタから放出される電子ビームのエネルギ分布
の半値幅ΔＥが大きく、電子顕微鏡の分解能が悪かっ
た。また、このようなエミッタでは、図７のＡに示すよ
うに電子ビームの電流密度分布が放出電子密度のように
平坦電子放出面半径近傍において、電界強度が増すた
め、高くなってしまい、電子間相互作用が高まり、ΔＥ
が更に拡がってしまうという問題点があった。As described above, in the conventional emitter having the flat electron emission surface 2 and the emitter radius of about 0.5 μm, the half value width ΔE of the energy distribution of the electron beam emitted from the emitter is large and the resolution of the electron microscope is high. Was bad. Further, in such an emitter, as shown in A of FIG. 7, the current density distribution of the electron beam becomes high near the flat electron emission surface radius near the flat electron emission surface radius like the emission electron density, and therefore becomes high. Interaction increases, ΔE
However, there was a problem that it spread further.
【００１７】上記した問題点を解決するために、エミッ
タの先端部温度、および、先端近傍の電界強度を上述し
た条件値（ほぼ１８００Ｋ、ほぼ２×１０7 （Ｖ／ｃ
ｍ）〜３×１０7 （Ｖ／ｃｍ））から外すと（例えば、
前記ΔＥを下げるために、電界強度を更に下げる）、エ
ミッタ先端部上にある、平坦電子放出面を形成している
公知のＺｒＯ／Ｗ（１００）複合体が、崩れだし、平坦
電子放出面が小さくなり、やがては消滅してしまう。そ
の過程においては、エミッタから放出される電子ビーム
が安定せず、次第にエミッション量が小さくなり、最後
には、エミッションしなくなるという問題点があった。In order to solve the above problems, the temperature at the tip of the emitter and the electric field strength near the tip are set to the above-mentioned conditional values (approximately 1800K, approximately 2 × 10 7 (V / c)
m) to 3 × 10 7 (V / cm)) (for example,
In order to lower the ΔE, the electric field strength is further reduced), and the known ZrO / W (100) complex forming the flat electron emission surface on the tip of the emitter begins to collapse and the flat electron emission surface is It gets smaller and eventually disappears. In the process, there was a problem that the electron beam emitted from the emitter was not stable, the emission amount was gradually reduced, and finally the emission was stopped.
【００１８】本発明は、このような点に鑑みてなされた
もので、その目的は、高い輝度で放出される電子ビーム
のエネルギ分布の幅が狭く、また、長時間安定してエミ
ッションを行うことができる熱電界放出電子銃および熱
電界放出電子銃用エミッタの製造方法を実現するにあ
る。The present invention has been made in view of the above circumstances, and an object thereof is to have a narrow energy distribution width of an electron beam emitted with high brightness and to perform stable emission for a long time. A method of manufacturing a thermal field emission electron gun and an emitter for a thermal field emission electron gun is realized.
【００１９】[0019]
【課題を解決するための手段】本発明に実施の形態を説
明する前に、まず、本発明に至った過程と原理について
説明する。熱電界放出電子銃において、先端部の半径が
ほぼ２μｍ〜４μｍの範囲のエミッタを使用して、エミ
ッタ先端近傍での電界強度をほぼ４×１０6 （Ｖ／ｃ
ｍ）〜６×１０6 （Ｖ／ｃｍ）の範囲とすることで、電
子放出のプロセスがポテンシャル障壁Ｖ（ｘ）を乗り越
えて放出するプロセスとなるショットキーエミッション
となる。Before describing the embodiments of the present invention, first, the process and the principle of the present invention will be described. In a thermal field emission electron gun, an emitter whose tip radius is in the range of approximately 2 μm to 4 μm is used, and the electric field strength near the tip of the emitter is approximately 4 × 10 6 (V / c).
The range of m) to 6 × 10 6 (V / cm) provides Schottky emission in which the electron emission process is a process of overcoming the potential barrier V (x) and emitting.
【００２０】この結果、図１に示すように、熱電界放出
電子のエネルギ分布幅を小さくすることができる。な
お、図３に示すように、仕事関数φｗが小さくなれば、
フェルミレベルＥF が上昇し、ポテンシャル障壁Ｖ
（ｘ）を乗り越えやすくなるので、例えば、エミッタの
先端をＺｒＯ2 によって表面処理し、Ｚｒ／Ｏ／Ｗ（１
００）複合体を形成することにより、Ｗ（１００）方位
の仕事関数を低めることができる。そのため、エミッタ
先端の半径を前記のごとく２．０μｍ以上にしても、十
分なエミッション量を得ることができる。As a result, as shown in FIG. 1, the energy distribution width of thermal field emission electrons can be reduced. As shown in FIG. 3, if the work function φw becomes smaller,
Fermi level E F rises and potential barrier V
Since it is easy to get over (x), for example, the tip of the emitter is surface-treated with ZrO 2 and Zr / O / W (1
By forming a (00) complex, the work function in the W (100) direction can be lowered. Therefore, even if the radius of the tip of the emitter is 2.0 μm or more as described above, a sufficient emission amount can be obtained.
【００２１】また、エミッタ形状は、エミッタ温度とエ
ミッタ先端での電界強度とにより変化する。このエミッ
タ形状の変化は、エミッタ先端の半径をｒ（ｃｍ）、時
間をｔとすると、エミッタ先端の鈍化率（ｄｒ／ｄｔ）
で表される。この鈍化率は、次の式により表される。Further, the shape of the emitter changes depending on the emitter temperature and the electric field strength at the tip of the emitter. This change in the emitter shape is such that the radius of the tip of the emitter is r (cm) and the time is t, the blunting rate of the tip of the emitter (dr / dt).
It is represented by. This blunting rate is expressed by the following equation.
【００２２】
ｄｒ／ｄｔ＝｛１−（ｒＦ2 ／８πγ）（ｄｒ／ｄｔ）O ｝ …（１）
上式において、Ｆはエミッタ先端での電界強度［Ｖ／ｃ
ｍ］、γは表面張力［ｄｙｎｅ／ｃｍ］で、（ｄｒ／ｄ
ｔ）O は、電界のない場合、すなわち、エミッタ温度Ｔ
のみでのエミッタの鈍化率であり、これは、次のように
表される。Dr / dt = {1- (rF 2 / 8πγ) (dr / dt) O } (1) In the above equation, F is the electric field strength [V / c at the tip of the emitter.
m] and γ are the surface tension [dyne / cm], which is (dr / d
t) O is in the absence of an electric field, that is, the emitter temperature T
The blunting rate of the emitter at only, which is expressed as:
【００２３】
（ｄｒ／ｄｔ）O ＝１．２５γΩO ＤO αｅｘｐ（−Ｅｄ／ｋＴ）
×（ＡO ｋ・Ｔｒ3 ）-1 …（２）
上式で、ΩO は原子の体積［ｃｍ3］、ＡO は原子の表
面積［ｃｍ2 ］、ＤOは拡散度［ｃｍ2 ／ｓｅｃ］、Ｅ
ｄは表面拡散活性化エネルギ［ｅＶ］、αはエミッタの
コーン角［ｒａｄ］である。[0023] (dr / dt) O = 1.25γΩ O D O αexp (-Ed / kT) × (A O k · Tr 3) -1 ... (2) In the above equation, Omega O is the volume of atoms [cm 3 ], A O is the atomic surface area [cm 2 ], D O is the diffusivity [cm 2 / sec], E
d is the surface diffusion activation energy [eV], and α is the cone angle [rad] of the emitter.
【００２４】上記した（１）式より、鈍化率（ｄｒ／ｄ
ｔ）の符号は、１−（γＦ2 ／８πｒ）により定まるこ
とがわかる。すなわち、エミッタ先端での電界強度Ｆの
値により、鈍化率（ｄｒ／ｄｔ）の符号は、次のように
分類される。From the above equation (1), the blunting rate (dr / d
It can be seen that the sign of t) is determined by 1- (γF 2 / 8πr). That is, the sign of the blunting rate (dr / dt) is classified as follows according to the value of the electric field strength F at the tip of the emitter.
【００２５】
Ｆ＜（８πγ）1/2 の時、（ｄｒ／ｄｔ）＞０ … 条件（ａ）
Ｆ＝（８πγ）1/2 の時、（ｄｒ／ｄｔ）＝０ … 条件（ｂ）
Ｆ＞（８πγ）1/2 の時、（ｄｒ／ｄｔ）＜０ … 条件（ｃ）
上記条件（ａ）の場合は、鈍化率（ｄｒ／ｄｔ）が正
で、エミッタ先端半径は次第に大きくなり、エミッタ形
状が変化していき、エミッションが不安定となる。条件
（ｂ）の場合は、表面拡散力と静電力とが釣り合ってい
る状態で、鈍化率（ｄｒ／ｄｔ）は０となり、計算上で
はエミッタ形状は変化しない。しかし、エミッタ先端で
の電界強度は非一様なために、この状態を維持するのは
極めて困難であり、実際にはエミッタ形状が変化する。When F <(8πγ) 1/2 , (dr / dt)> 0 ... Condition (a) When F = (8πγ) 1/2 , (dr / dt) = 0 ... Condition (b) F > (8πγ) 1/2 , (dr / dt) <0 ... Condition (c) In the case of the above condition (a), the blunting ratio (dr / dt) is positive and the emitter tip radius gradually increases, The shape of the emitter changes and the emission becomes unstable. In the case of the condition (b), the blunting ratio (dr / dt) is 0 in the state where the surface diffusion force and the electrostatic force are balanced, and the emitter shape does not change in the calculation. However, since the electric field strength at the tip of the emitter is non-uniform, it is extremely difficult to maintain this state, and the shape of the emitter actually changes.
【００２６】上記条件（ｃ）の場合は、鈍化率（ｄｒ／
ｄｔ）が負で、計算上ではエミッタ形状は細くなる。し
かし、実際には、鈍化率（ｄｒ／ｄｔ）が負であっても
０に近いときに、フィールドビルトアップ（Field Buil
dup ）と呼ばれる複雑な工程が発生し、エミッタ表面に
多面体が生じ、エミッタ先端に形状の安定したファセッ
トが形成される。すなわち、前記した条件（ａ）および
（ｂ）の場合には、エミッタ形状が不安定となり、条件
（ｃ）の場合には安定となる。これらのことから、エミ
ッションは、条件（ｃ）において、エミッタ先端での電
界強度Ｆが条件（ｂ）の場合の電界強度より少し大きい
場合に安定することがわかる。In the case of the above condition (c), the blunting rate (dr /
Since dt) is negative, the emitter shape becomes thin in calculation. However, in reality, even if the slowing rate (dr / dt) is negative, when the field build-up (Field Build
A complicated process called dup) occurs, a polyhedron is formed on the emitter surface, and a stable facet is formed at the tip of the emitter. That is, the emitter shape becomes unstable under the conditions (a) and (b) described above, and becomes stable under the condition (c). From these, it is understood that the emission is stable under the condition (c) when the electric field intensity F at the tip of the emitter is slightly larger than the electric field intensity under the condition (b).
【００２７】この条件は、従来の熱電界放出電子銃にお
いては、エミッタ半径ｒが、ほぼ０．５μｍの場合、エ
ミッタ先端部の電界強度をほぼ２×１０7 （Ｖ／ｃｍ）
〜３×１０7 （Ｖ／ｃｍ）に、エミッタ先端部の温度を
ほぼ１８００Ｋにすることで得られる。この場合に、エ
ミッタ先端部には、前記平坦電子放出面が形成される
が、上述した問題点が残るのである。This condition is that in the conventional thermal field emission electron gun, when the emitter radius r is about 0.5 μm, the electric field strength at the tip of the emitter is about 2 × 10 7 (V / cm).
It can be obtained by setting the temperature at the tip of the emitter to approximately 1800 K at ˜3 × 10 7 (V / cm). In this case, the flat electron emission surface is formed at the tip of the emitter, but the above-mentioned problems remain.
【００２８】本発明では、前記ΔＥをほぼ０．５ｅＶと
するために、エミッタ先端近傍の電界強度Ｆをほぼ４×
１０6 （Ｖ／ｃｍ）〜６×１０6 （Ｖ／ｃｍ）にするた
めに、エミッタ先端半径ｒをほぼ２．０μｍ〜４μｍと
したものである。これは、前記した条件（ｂ）の（ｄｒ
／ｄｔ）＝０となる場合の電界強度条件式
ＦO ＝（８πγ）1/2 ≠８．１×１０4 ｒ-1/2 ［Ｖ／
ｃｍ］
から、ｒ＝２．０μｍの時、ＦO ＝５．７×１０6 （Ｖ
／ｃｍ）、ｒ＝４．０μｍの時、ＦO ＝４．０５×１０
6 （Ｖ／ｃｍ）となることから見積もった。In the present invention, the electric field strength F in the vicinity of the tip of the emitter is set to about 4 × so that the ΔE is set to about 0.5 eV.
The emitter tip radius r is set to approximately 2.0 μm to 4 μm so as to be 10 6 (V / cm) to 6 × 10 6 (V / cm). This is (dr) of the condition (b) described above.
/ Dt) = 0 and field strength conditional expressions may become F O = (8πγ) 1/2 ≠ 8.1 × 10 4 r -1/2 [V /
cm], and when r = 2.0 μm, F O = 5.7 × 10 6 (V
/ Cm) and r = 4.0 μm, F O = 4.05 × 10
It was estimated from 6 (V / cm).
【００２９】エミッタ先端近傍の電界強度が、ほぼ４×
１０6 （Ｖ／ｃｍ）より小さくなると、エミッション量
が電子顕微鏡に供するには小さくなってしまい、このこ
とから、エミッションが安定し、かつ、ΔＥをほぼ０．
５ｅＶにするエミッタ先端半径の大きさは、最大ｒ＝
４．０μｍくらいが限度である。The electric field strength near the tip of the emitter is approximately 4 ×.
If it is smaller than 10 6 (V / cm), the amount of emission becomes small for use in an electron microscope, which means that the emission is stable and ΔE is almost 0.
The maximum radius of the emitter tip to be 5 eV is r =
The limit is about 4.0 μm.
【００３０】また、ｒ＝４．０μｍ以上では、電子光源
の大きさが大きくなってしまい、かえって電子プローブ
径を大きくしてしまう。更に、従来のエミッタ半径ｒが
ほぼ０．５μｍのエミッタでは、エミッタ先端部の安定
条件（ｃ）を少しでも外れると、式（１）による（ｄｒ
／ｄｔ）が大きいため、エミッタ先端での形状が崩れだ
し、すぐに、エミッションがなくなってしまう。しか
し、エミッタ半径がほぼ２μｍ〜４μｍでは、条件
（ｃ）から外れても、ｄｒが極めて小さいため、エミッ
タ先端部位が崩れることはなく、エミッションも安定す
る。Further, when r = 4.0 μm or more, the size of the electron light source becomes large, and the diameter of the electron probe becomes large. Further, in the conventional emitter having an emitter radius r of about 0.5 μm, if the stability condition (c) at the tip of the emitter is deviated from by a little, (dr
Since / dt) is large, the shape at the tip of the emitter begins to collapse, and the emission disappears immediately. However, when the emitter radius is approximately 2 μm to 4 μm, even if the condition (c) is not satisfied, dr is extremely small, so that the emitter tip portion does not collapse and the emission is stable.
【００３１】すなわち、本発明によるエミッタは、従来
の熱電界放出電子銃のように、電子ビームを安定化させ
る条件（ｃ）を満足するような、ほぼ２×１０7 （Ｖ／
ｃｍ）〜３×１０7 （Ｖ／ｃｍ）の電界強度をエミッタ
先端部にかけ、平坦電子放出面を形成する必要はなく、
ΔＥを下げるために、むしろ、条件（ａ）となるような
電界強度を与える。That is, the emitter according to the present invention, as in the conventional thermal field emission electron gun, satisfies the condition (c) for stabilizing the electron beam and is approximately 2 × 10 7 (V /
cm) to 3 × 10 7 (V / cm), it is not necessary to apply a field intensity to the emitter tip to form a flat electron emission surface.
In order to reduce ΔE, the electric field intensity that satisfies the condition (a) is given.
【００３２】すなわち、従来の熱電界放出電子銃による
電子放出システムの設計に用いられる条件（ｃ）を満足
するようなエミッタ先端径ｒに見合う電界強度をかけ
て、平坦電子放出面を形成するのではなく、本発明で
は、エミッタ半径ｒをほぼ２μｍ〜４μｍにし、条件
（ａ）を満足するようなエミッタ半径ｒに見合う電界強
度をかけ、ΔＥを低め、かつ、電子ビームの安定度を得
るようにしている。That is, a flat electron emission surface is formed by applying an electric field intensity commensurate with the emitter tip diameter r satisfying the condition (c) used for designing an electron emission system using a conventional thermal field emission electron gun. Instead, in the present invention, the emitter radius r is set to approximately 2 μm to 4 μm, and an electric field intensity commensurate with the emitter radius r that satisfies the condition (a) is applied to reduce ΔE and obtain the electron beam stability. I have to.
【００３３】したがって、請求項１の発明に基づく熱電
界放出電子銃は、エミッタと引出電極とを備えており、
エミッタを加熱すると共に、エミッタと引出電極との間
に引出電圧を印加するようにした熱電界放出電子銃にお
いて、軸方位が＜１００＞のタングステン単結晶針より
なるエミッタの先端部の半径をほぼ２μｍ〜４μｍと
し、エミッタの先端部にジルコニウム（Ｚｒ）と酸素
（Ｏ）からなる数層から数十層の積層電子放出面を設け
ると共に、エミッタ先端部の半径ｒと、エミッタ先端に
形成された積層電子放出面の積層電子放出面最外郭半径
ａとの比（ａ／ｒ）をほぼ０．４としたことを特徴とし
ている。Therefore, the thermal field emission electron gun according to the invention of claim 1 is provided with an emitter and an extraction electrode,
In a thermal field emission electron gun that heats the emitter and applies an extraction voltage between the emitter and the extraction electrode, a tungsten single crystal needle having an axial orientation of <100>
Becomes the radius of the emitter tip portion substantially as 2Myuemu～4myuemu, oxygen and zirconium (Zr) on the tip portion of the emitter
In addition to providing several to several tens of stacked electron emission surfaces made of (O) , the ratio of the radius r of the emitter tip to the outermost radius a of the stacked electron emission surface of the stacked electron emission surface formed at the emitter tip. The feature is that (a / r) is approximately 0.4.
【００３４】請求項１の発明では、軸方位が＜１００＞
のタングステン単結晶針よりなるエミッタの先端部の半
径をほぼ２μｍ〜４μｍとし、エミッタの先端部にジル
コニウムと酸素からなる数層から数十層の積層電子放出
面を設けた。また、エミッタ先端部の半径ｒと、エミッ
タ先端に形成された積層電子放出面の積層電子放出面最
外郭半径ａとの比（ａ／ｒ）をほぼ０．４とした。請求
項２の発明は、請求項１記載の熱電界放出電子銃におい
て、数層から数十層の積層電子放出面により、エミッタ
先端部の形状をほぼ球状としたことを特徴としている。In the invention of claim 1, the axis direction is <100>.
Almost a 2μm~4μm the radius of the tungsten single crystal needle made of the emitter of the tip, Jill the tip of the emitter
Several to several tens of laminated electron emission surfaces made of conium and oxygen were provided. The ratio (a / r) between the radius r of the emitter tip and the outermost radius a of the laminated electron emission surface of the laminated electron emission surface formed at the emitter tip was set to approximately 0.4. According to a second aspect of the present invention, in the thermal field emission electron gun according to the first aspect, the shape of the tip of the emitter is substantially spherical due to the laminated electron emission surface of several layers to several tens of layers.
【００３５】請求項３の発明は、請求項１記載の熱電界
放出電子銃において、積層電子放出面の近傍の電界強度
が、ほぼ４×１０6 （Ｖ／ｃｍ）〜６×１０6 （Ｖ／ｃ
ｍ）の範囲となるように、引出電圧を設定したことを特
徴としてる。According to a third aspect of the present invention, in the thermal field emission electron gun according to the first aspect, the electric field strength in the vicinity of the stacked electron emission surface is approximately 4 × 10 6 (V / cm) to 6 × 10 6 (V). / C
The extraction voltage is set so as to fall within the range of m).
【００３６】請求項４の発明は、請求項１記載の熱電界
放出電子銃において、放出される電子ビームのエネルギ
幅をほぼ０．５ｅＶ以下としたことを特徴としている。
請求項５の発明は、請求項３記載の熱電界放出電子銃に
おいて、エミッタの温度をほぼ１８００Ｋとしたことを
特徴としている。According to a fourth aspect of the present invention, in the thermal field emission electron gun according to the first aspect, the energy width of the emitted electron beam is set to approximately 0.5 eV or less.
According to a fifth aspect of the present invention, in the thermal field emission electron gun according to the third aspect, the temperature of the emitter is set to approximately 1800K.
【００３７】[0037]
【００３８】請求項６に基づく発明は、エミッタと引出
電極とを備えており、エミッタを加熱すると共に、エミ
ッタと引出電極との間に引出電圧を印加するようにした
熱電界放出電子銃用のエミッタの製造方法において、軸
方位が＜１００＞のタングステン単結晶針よりなるエミ
ッタを真空中においてほぼ１８００Ｋに加熱しつつ、エ
ミッタ先端部の電界強度をほぼ４×１０6 （Ｖ／ｃｍ）
〜６×１０6 （Ｖ／ｃｍ）の範囲に維持し、エミッタ先
端部にジルコニウムと酸素からなる数層から数十層から
なる積層電子放出面を、エミッタ先端部の半径ｒと、エ
ミッタ先端に形成された積層電子放出面の積層電子放出
面最外郭半径ａとの比（ａ／ｒ）がほぼ０．４となるよ
うに形成するようにしたことを特徴としている。According to a sixth aspect of the present invention, there is provided an emitter and an extraction electrode, which is for a thermal field emission electron gun, which heats the emitter and applies an extraction voltage between the emitter and the extraction electrode. In the method of manufacturing the emitter, the axis
While the emitter made of a tungsten single crystal needle having an orientation of <100> is heated to about 1800 K in a vacuum, the electric field strength at the tip of the emitter is set to about 4 × 10 6 (V / cm).
Maintained in the range of up to 6 × 10 6 (V / cm), the emitter tip has a laminated electron emission surface consisting of several to several tens of layers of zirconium and oxygen , and the emitter tip has a radius r and an emitter tip. The feature is that the ratio (a / r) of the formed stacked electron emission surface to the outermost radius a of the stacked electron emission surface is approximately 0.4.
【００３９】[0039]
【発明の実施の形態】以下、図面を参照して本発明の実
施の形態を詳細に説明する。図４は本発明に基づく熱電
界放出電子銃の基本構成を示している。図中１０はエミ
ッタであり、エミッタ１０はタングステン単結晶の先端
をＺｒＯ2 によって表面処理をして形成されており、Ｚ
ｒ／Ｏ／Ｗ（１００）複合体とされている。このエミッ
タ１０は、図示していないが、タングステン製のフィラ
メントにスポット溶接等により取り付けられている。こ
のフィラメントに加熱電流を供給することにより、フィ
ラメントを加熱し、その結果、間接的にエミッタ１０を
加熱するように構成されている。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 4 shows the basic structure of a thermal field emission electron gun according to the present invention. In the figure, 10 is an emitter, and the emitter 10 is formed by subjecting the tip of a tungsten single crystal to a surface treatment with ZrO 2 .
It is regarded as an r / O / W (100) complex. Although not shown, the emitter 10 is attached to a tungsten filament by spot welding or the like. By supplying a heating current to the filament, the filament is heated, and as a result, the emitter 10 is indirectly heated.
【００４０】このエミッタ１０に接近して引出電極１１
が配置され、エミッタ１０と引出電極１１との間には、
図示していない引出電圧電源から所望の引出電圧が印加
される。この引出電圧の印加により、エミッタ１０先端
部の電子放出面１２から電子が放出される。放出された
電子は、引出電極１１の先に設けられた接地電位のアノ
ード（図示せず）によって加速される。なお、エミッタ
１０とアノードとの間には、加速電圧が印加される。The extraction electrode 11 is brought close to the emitter 10.
Is arranged, and between the emitter 10 and the extraction electrode 11,
A desired extraction voltage is applied from an extraction voltage power supply (not shown). By applying this extraction voltage, electrons are emitted from the electron emission surface 12 at the tip of the emitter 10. The emitted electrons are accelerated by a ground potential anode (not shown) provided in front of the extraction electrode 11. An acceleration voltage is applied between the emitter 10 and the anode.
【００４１】このエミッタ１０の形状の詳細を図５に示
す。図５（ａ）はエミッタ１０の先端部位を真横から見
た図、図５（ｂ）はエミッタ先端部を少し傾斜させて見
た図である。The details of the shape of the emitter 10 are shown in FIG. FIG. 5A is a view of the tip portion of the emitter 10 as seen from the side, and FIG. 5B is a view of the tip portion of the emitter with a slight inclination.
【００４２】このエミッタ１０は、次の工程によって製
作される。まず、エミッタ半径ｒをほぼ２μｍ〜４μｍ
にし、真空中にて、前記した条件（ａ）を満足するよう
なエミッタ先端半径ｒに見合う電界強度（ほぼ４×１０
6 （Ｖ／ｃｍ）〜６×１０6（Ｖ／ｃｍ））をかける。
そして、エミッタ先端部温度をほぼ１８００Ｋとして、
電子放出をほぼ２４時間続ける。The emitter 10 is manufactured by the following steps. First, the emitter radius r is set to approximately 2 μm to 4 μm.
Then, in a vacuum, the electric field strength (approximately 4 × 10 4) which is commensurate with the emitter tip radius r that satisfies the above-mentioned condition (a).
6 (V / cm) to 6 × 10 6 (V / cm)) is applied.
Then, the temperature at the tip of the emitter is set to approximately 1800K,
Electron emission continues for approximately 24 hours.
【００４３】このような製作工程により、エミッタ１０
の先端部には、結晶成長とエミッタ先端部位の表面張力
と電界による吸引力との釣り合いから、層の厚みｄがほ
ぼ０．０１ｎｍ〜０．２ｎｍである（１００）方位に垂
直な半径の異なる同心円板状の層が、数〜数十層積み重
ねられた積層電子放出面１２が形成される。この積層電
子放出面１２の拡大図を図６に示す。Through the above manufacturing process, the emitter 10
The thickness of the layer is approximately 0.01 nm to 0.2 nm at the tip end of the layer due to the balance between the crystal growth, the surface tension of the tip end portion of the emitter, and the attractive force due to the electric field. The laminated electron emission surface 12 is formed by stacking several to several tens of concentric disk-shaped layers. An enlarged view of the laminated electron emission surface 12 is shown in FIG.
【００４４】数〜数十層からなる積層電子放出面１２
は、一度形成されると、エミッタ先端半径ｒがほぼ２μ
ｍ〜４μｍのため、（ｄｒ／ｄｔ）が極めて小さく、熱
電界放出電子銃の寿命（通例、塗布されたＺｒＯが消失
するまでの期間、ほぼ５０００時間以上）内で、消失す
ることはない。Stacked electron emission surface 12 consisting of several to several tens of layers
Once formed, the emitter tip radius r is approximately 2μ
Since it is from m to 4 μm, (dr / dt) is extremely small, and it does not disappear within the life of the thermal field emission electron gun (usually, the time until the coated ZrO disappears, about 5000 hours or more).
【００４５】また、エミッタ１０の先端に、積層電子放
出面１２を形成すると、エミッタ先端部が従来の平坦電
子放出面ではなく、積層構造になっているため、電界強
度が緩和され、エミッタの放出電子密度分布が、一様な
放出電子密度分布となるため、電子間相互作用が弱ま
り、エネルギ分布幅ΔＥが更に小さくなる。Further, when the laminated electron emission surface 12 is formed at the tip of the emitter 10, the electric field strength is relaxed because the tip of the emitter has a laminated structure instead of the conventional flat electron emission surface, and the emitter is emitted. Since the electron density distribution becomes a uniform emission electron density distribution, the interaction between electrons is weakened, and the energy distribution width ΔE is further reduced.
【００４６】この様子を図７に示す。図７の横軸は電子
の放出角（ｒａｄ）であり、縦軸は放出電子密度であ
る。この図７のＡの分布は従来の平坦電子放出面による
もの、Ｂの分布は本発明の積層構造の電子放出面による
ものである。This state is shown in FIG. The horizontal axis of FIG. 7 is the electron emission angle (rad), and the vertical axis is the emission electron density. The distribution of A in FIG. 7 is due to the conventional flat electron emission surface, and the distribution of B is due to the electron emission surface of the laminated structure of the present invention.
【００４７】また、エミッタの先端半径ｒと、エミッタ
の先端に形成された積層電子放出面の積層電子放出面最
外郭半径ａとの比（ａ／ｒ）は、従来の熱電界放出電子
銃における、エミッタ先端半径ｒと平坦電子放出面の平
坦電子放出面半径ｂとの比（ｂ／ｒ）がほぼ０．３であ
るのに対し、ほぼ０．４となる。なお、このメカニズム
は不明だが、実験的にほぼ０．４となり、本発明による
エミッタの特徴である。また、エミッタ１０の先端部１
４は、積層電子放出面１２を含め、全体として球状に形
成される。Further, the ratio (a / r) of the tip radius r of the emitter to the outermost radius a of the laminated electron emission surface of the laminated electron emission surface formed at the tip of the emitter is the same as in the conventional thermal field emission electron gun. The ratio (b / r) between the emitter tip radius r and the flat electron emission surface radius b of the flat electron emission surface is approximately 0.3, while it is approximately 0.4. Although the mechanism is unknown, it is experimentally about 0.4, which is a feature of the emitter according to the present invention. In addition, the tip 1 of the emitter 10
4 is formed in a spherical shape as a whole, including the laminated electron emission surface 12.
【００４８】以上本発明を説明したが、本発明は上記実
施の形態に限定されない。 [0048] The present invention has been described above, this invention is not such limited to the above embodiments.
【００４９】[0049]
【発明の効果】請求項１の発明では、軸方位が＜１００
＞のタングステン単結晶針よりなるエミッタの先端部の
半径をほぼ２μｍ〜４μｍとし、エミッタの先端部にジ
ルコニウムと酸素からなる数層から数十層の積層電子放
出面を設けた。また、エミッタ先端部の半径ｒと、エミ
ッタ先端に形成された積層電子放出面の積層電子放出面
最外郭半径ａとの比（ａ／ｒ）をほぼ０．４とした。そ
の結果、放出される電子ビームのエネルギ分布幅を著し
く小さくすることができる。また、一様な放出電子密度
の電子ビームを得ることができると共に、長時間安定な
エミッションを維持させることができる。According to the invention of claim 1, the axial direction is <100.
Almost a 2μm~4μm the radius of the tungsten single crystal needle made of the emitter of the tip>, di the tip of the emitter
A few to several tens of laminated electron emission surfaces composed of ruconium and oxygen were provided. The ratio (a / r) between the radius r of the emitter tip and the outermost radius a of the laminated electron emission surface of the laminated electron emission surface formed at the emitter tip was set to approximately 0.4. As a result, the energy distribution width of the emitted electron beam can be significantly reduced. Further, it is possible to obtain an electron beam having a uniform emission electron density and to maintain stable emission for a long time.
【００５０】更に、積層電子放出面を形成することによ
り、エミッタ先端部にかかる電界強度が緩和されるた
め、積層電子放出面が崩れにくくなり、エミッションノ
イズを極めて小さくすることができる。そして、このよ
うな電子銃を電子顕微鏡に用いると、電子レンズによる
色収差を小さくできるので、電子顕微鏡の分解能を向上
させることができる。Further, since the electric field strength applied to the tip of the emitter is relaxed by forming the laminated electron emission surface, the laminated electron emission surface is less likely to collapse and the emission noise can be made extremely small. When such an electron gun is used in an electron microscope, chromatic aberration due to the electron lens can be reduced, so that the resolution of the electron microscope can be improved.
【００５１】請求項２の発明は、請求項１記載の熱電界
放出電子銃において、数層から数十層の積層電子放出面
により、エミッタ先端部の形状をほぼ球状としたことを
特徴としている。したがって、電子放出方向が球を中心
とする放射状に近付き、仮想光源を小さくすることがで
きる。According to a second aspect of the present invention, in the thermal field emission electron gun according to the first aspect, the shape of the tip of the emitter is made substantially spherical by the laminated electron emission surface of several layers to several tens of layers. . Therefore, the electron emission direction approaches a radial shape centered on the sphere, and the virtual light source can be made small.
【００５２】請求項３の発明は、請求項１記載の熱電界
放出電子銃において、積層電子放出面の近傍の電界強度
が、ほぼ４×１０6 （Ｖ／ｃｍ）〜６×１０6 （Ｖ／ｃ
ｍ）の範囲となるように、引出電圧を設定したことを特
徴としており、請求項１と同様な効果が達成される。According to a third aspect of the present invention, in the thermal field emission electron gun according to the first aspect, the electric field strength near the stacked electron emission surface is approximately 4 × 10 6 (V / cm) to 6 × 10 6 (V). / C
The extraction voltage is set so as to be in the range of m), and the same effect as in claim 1 is achieved.
【００５３】請求項４の発明は、請求項１記載の熱電界
放出電子銃において、放出される電子ビームのエネルギ
幅をほぼ０．５ｅＶ以下としており、電子ビームのエネ
ルギ分布幅を著しく小さくすることができる。According to a fourth aspect of the present invention, in the thermal field emission electron gun according to the first aspect, the energy width of the emitted electron beam is approximately 0.5 eV or less, and the energy distribution width of the electron beam is remarkably reduced. You can
【００５４】請求項５の発明は、請求項３記載の熱電界
放出電子銃において、エミッタの温度をほぼ１８００Ｋ
としたことを特徴としており、請求項１と同様な効果が
達成される。According to a fifth aspect of the present invention, in the thermal field emission electron gun according to the third aspect, the emitter temperature is approximately 1800K.
And the same effect as that of claim 1 is achieved.
【００５５】[0055]
【００５６】請求項６に基づく発明は、エミッタと引出
電極とを備えており、エミッタを加熱すると共に、エミ
ッタと引出電極との間に引出電圧を印加するようにした
熱電界放出電子銃用のエミッタの製造方法において、軸
方位が＜１００＞のタングステン単結晶針よりなるエミ
ッタを真空中においてほぼ１８００Ｋに加熱しつつ、エ
ミッタ先端部の電界強度をほぼ４×１０6 （Ｖ／ｃｍ）
〜６×１０6 （Ｖ／ｃｍ）の範囲に維持し、エミッタ先
端部にジルコニウムと酸素からなる数層から数十層から
なる積層電子放出面を、エミッタ先端部の半径ｒと、エ
ミッタ先端に形成された積層電子放出面の積層電子放出
面最外郭半径ａとの比（ａ／ｒ）がほぼ０．４となるよ
うに形成するようにしたことを特徴としている。したが
って、このような製造方法に基づいて作成されたエミッ
タを用いる電子銃は、請求項１と同様な効果が得られ
る。According to a sixth aspect of the present invention, there is provided an emitter and an extraction electrode for a thermal field emission electron gun, which heats the emitter and applies an extraction voltage between the emitter and the extraction electrode. In the method of manufacturing the emitter, the axis
While the emitter made of a tungsten single crystal needle having an orientation of <100> is heated to about 1800 K in a vacuum, the electric field strength at the tip of the emitter is set to about 4 × 10 6 (V / cm).
Maintained in the range of up to 6 × 10 6 (V / cm), the emitter tip has a laminated electron emission surface consisting of several to several tens of layers of zirconium and oxygen , and the emitter tip has a radius r and an emitter tip. The feature is that the ratio (a / r) of the formed stacked electron emission surface to the outermost radius a of the stacked electron emission surface is approximately 0.4. Therefore, the electron gun using the emitter manufactured based on such a manufacturing method can obtain the same effect as that of claim 1.
【図１】エミッタ先端の電界強度と放出電子のエネルギ
分布幅との関係を示す図である。FIG. 1 is a diagram showing the relationship between the electric field strength at the tip of an emitter and the energy distribution width of emitted electrons.
【図２】従来のエミッタの先端形状を示す図である。FIG. 2 is a view showing a tip shape of a conventional emitter.
【図３】エミッタ先端付近のエネルギ図である。FIG. 3 is an energy diagram near the tip of the emitter.
【図４】本発明に基づく熱電界放出電子銃の基本構成を
示す図である。FIG. 4 is a diagram showing a basic configuration of a thermal field emission electron gun according to the present invention.
【図５】本発明に基づくエミッタの先端形状を示す図で
ある。FIG. 5 is a diagram showing the tip shape of an emitter according to the present invention.
【図６】積層電子放出面の拡大図である。FIG. 6 is an enlarged view of a stacked electron emission surface.
【図７】エミッタの放出電子密度分布を示す図である。FIG. 7 is a diagram showing an emission electron density distribution of an emitter.
１０ エミッタ １１ 引出電極 １２ 積層電子放出面 10 Emitter 11 Extraction electrode 12 Stacked electron emission surface
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) H01J 37/073 H01J 1/30 H01J 9/02 ─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. 7 , DB name) H01J 37/073 H01J 1/30 H01J 9/02
Claims (6)
ミッタを加熱すると共に、エミッタと引出電極との間に
引出電圧を印加するようにした熱電界放出電子銃におい
て、軸方位が＜１００＞のタングステン単結晶針よりなる エ
ミッタの先端部の半径をほぼ２μｍ〜４μｍとし、エミ
ッタの先端部にジルコニウムと酸素からなる数層から数
十層の積層電子放出面を設けると共に、エミッタ先端部
の半径ｒと、エミッタ先端に形成された積層電子放出面
の積層電子放出面最外郭半径ａとの比（ａ／ｒ）をほぼ
０．４としたことを特徴とする熱電界放出電子銃。1. A includes an emitter and the extraction electrode, thereby heating the emitter, the thermal field emission electron gun so as to apply an extraction voltage between the emitter and the extraction electrode, the axis orientation <100> with the radius of the tip portion of the error <br/> emitter of tungsten single crystal needle substantially the 2Myuemu～4myuemu, provided a laminated electron emitting surface of several tens of layers of several layers consisting of zirconium and oxygen to the tip of the emitter, Thermal field emission characterized in that the ratio (a / r) of the radius r of the tip of the emitter to the outermost radius a of the laminated electron emission surface of the laminated electron emission surface formed at the emitter tip is set to approximately 0.4. Electron gun.
り、エミッタ先端部の形状をほぼ球状とした請求項１記
載の熱電界放出電子銃。2. The thermal field emission electron gun according to claim 1, wherein the emitter tip has a substantially spherical shape due to the laminated electron emission surfaces of several layers to several tens of layers.
ぼ４×１０6 （Ｖ／ｃｍ）〜６×１０6 （Ｖ／ｃｍ）の
範囲となるように、引出電圧を設定した請求項１記載の
熱電界放出電子銃。3. The extraction voltage is set so that the electric field strength in the vicinity of the stacked electron emission surface is in the range of approximately 4 × 10 6 (V / cm) to 6 × 10 6 (V / cm). 1. The thermal field emission electron gun according to 1.
ぼ０．５ｅＶ以下である請求項１記載の熱電界放出電子
銃。4. The thermal field emission electron gun according to claim 1, wherein the energy width of the emitted electron beam is approximately 0.5 eV or less.
請求項３記載の熱電界放出電子銃。5. A thermal field emission electron gun according to claim 3, wherein the temperature of the emitter is approximately 1800K.
ミッタを加熱すると共に、エミッタと引出電極との間に
引出電圧を印加するようにした熱電界放出電子銃用のエ
ミッタの製造方法において、軸方位が＜１００＞のタングステン単結晶針よりなる エ
ミッタを真空中においてほぼ１８００Ｋに加熱しつつ、
エミッタ先端部の電界強度をほぼ４×１０6 （Ｖ／ｃ
ｍ）〜６×１０6 （Ｖ／ｃｍ）の範囲に維持し、エミッ
タ先端部にジルコニウムと酸素からなる数層から数十層
からなる積層電子放出面を、エミッタ先端部の半径ｒ
と、エミッタ先端に形成された積層電子放出面の積層電
子放出面最外郭半径ａとの比（ａ／ｒ）がほぼ０．４と
なるように形成する熱電界放出電子銃用のエミッタの製
造方法。6. A method for manufacturing an emitter for a thermal field emission electron gun, comprising: an emitter and an extraction electrode, wherein the emitter is heated and an extraction voltage is applied between the emitter and the extraction electrode. While heating an emitter made of a tungsten single crystal needle having an axial orientation of <100> to about 1800K in vacuum ,
The electric field strength at the tip of the emitter is approximately 4 × 10 6 (V / c
m) to 6 × 10 6 (V / cm), and the emitter tip has a laminated electron emission surface consisting of several to several tens of layers of zirconium and oxygen, and the radius r of the emitter tip.
And an emitter for a thermal field emission electron gun, which is formed so that the ratio (a / r) of the laminated electron emission surface formed at the tip of the emitter to the outermost radius a of the laminated electron emission surface is approximately 0.4. Method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP02870797A JP3397616B2 (en) | 1997-02-13 | 1997-02-13 | Thermal field emission electron gun and method of manufacturing emitter for thermal field emission electron gun |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP02870797A JP3397616B2 (en) | 1997-02-13 | 1997-02-13 | Thermal field emission electron gun and method of manufacturing emitter for thermal field emission electron gun |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10228877A JPH10228877A (en) | 1998-08-25 |
| JP3397616B2 true JP3397616B2 (en) | 2003-04-21 |
Family
ID=12255936
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP02870797A Expired - Fee Related JP3397616B2 (en) | 1997-02-13 | 1997-02-13 | Thermal field emission electron gun and method of manufacturing emitter for thermal field emission electron gun |
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| Country | Link |
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| JP (1) | JP3397616B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPWO2002037527A1 (en) | 2000-11-02 | 2004-03-11 | 株式会社荏原製作所 | Electron beam apparatus and device manufacturing method using the same |
| EP1261016A4 (en) * | 2000-12-12 | 2007-06-27 | Ebara Corp | Electron beam device and semiconductor device production method using the device |
| JP2006114260A (en) * | 2004-10-13 | 2006-04-27 | Japan Atom Energy Res Inst | Forming method and system of emitter |
| JP5578612B2 (en) * | 2010-07-30 | 2014-08-27 | 株式会社リガク | Current control device for electron emission device |
| IL264627B2 (en) * | 2016-08-08 | 2023-04-01 | Asml Netherlands Bv | Electron emitter and method of fabricating same |
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1997
- 1997-02-13 JP JP02870797A patent/JP3397616B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH10228877A (en) | 1998-08-25 |
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