JPH0294237A - Thermal electric field emission cathode electron gun - Google Patents
Thermal electric field emission cathode electron gunInfo
- Publication number
- JPH0294237A JPH0294237A JP63242436A JP24243688A JPH0294237A JP H0294237 A JPH0294237 A JP H0294237A JP 63242436 A JP63242436 A JP 63242436A JP 24243688 A JP24243688 A JP 24243688A JP H0294237 A JPH0294237 A JP H0294237A
- Authority
- JP
- Japan
- Prior art keywords
- control electrode
- field emission
- stainless steel
- emission cathode
- electron
- 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 1
- 239000010935 stainless steel Substances 0.000 claims abstract description 16
- 229910001220 stainless steel Inorganic materials 0.000 claims abstract description 16
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 abstract description 4
- 229910052799 carbon Inorganic materials 0.000 abstract description 4
- 238000000034 method Methods 0.000 abstract description 3
- 238000005498 polishing Methods 0.000 abstract description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 abstract description 2
- 229910052804 chromium Inorganic materials 0.000 abstract description 2
- 239000011651 chromium Substances 0.000 abstract description 2
- 229910052759 nickel Inorganic materials 0.000 abstract description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 8
- 229910000831 Steel Inorganic materials 0.000 description 8
- 229910052750 molybdenum Inorganic materials 0.000 description 8
- 239000011733 molybdenum Substances 0.000 description 8
- 239000010959 steel Substances 0.000 description 8
- 238000010894 electron beam technology Methods 0.000 description 7
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 3
- 230000005389 magnetism Effects 0.000 description 2
- 238000010943 off-gassing Methods 0.000 description 2
- SCYULBFZEHDVBN-UHFFFAOYSA-N 1,1-Dichloroethane Chemical compound CC(Cl)Cl SCYULBFZEHDVBN-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000002845 discoloration Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Electron Sources, Ion Sources (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は電子顕微鏡、測長機、電子ビーム露光機などに
用いられている熱電界放射陰極電子銃に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal field emission cathode electron gun used in electron microscopes, length measuring machines, electron beam exposure machines, and the like.
熱電界放射陰極電子銃は熱陰極電子銃に比べて高輝度な
電子ビームが得られ、又、冷電界放射陰極電子銃に比べ
て長時間安定に動作し、かつ高電流の電子ビームが得ら
れるという特徴を持っている。しかしながら、その動作
特性上、電子放射チップ先端から得られる軸上電子ビー
ムのほかに、該電子放射チップを加熱するフィラメント
などから不用な熱電子が多量に放出される。この不用な
熱電子は電子放射チップ周辺に位置する陽極などに衝突
し、該陽極に吸着、吸蔵していたガスを放出する。放出
されたガスは該電子放射チップ周辺の真空度を劣化させ
、また同時にイオン化されて該電子放射チップに衝突す
る。そして最終的には放電が発生し、該電子放射チップ
は破損する。この様な問題を解決するために、電子放射
チップ及び加熱用フィラメントを制御電極（別称：サプ
レッサー電極、ショットキーシールド）で覆い、熱電子
の放出を抑える方法が知られている（特開昭４９−３８
１００号公報）。そして、この制御電極には従来、ガス
放出量が少ないということでモリブデン鋼が用いられて
いる（Ｆｔ！Ｉ Ｃｏｍｐａｎｙ発行のバ呼フレット“
ＴＨＥＲＭＡＬ ＦＩＥＬＤ ＥＭＩＴＴＥＲ０ＰＥＲ
ＡＴＩＮＧＩＮＳＴＲ１ｌＣＴＩＯＮＳ ＪＡＮＵＡＲ
Ｙ、 １９８７ ” （７） ２頁）。Thermal field emission cathode electron guns can provide a higher brightness electron beam than hot cathode electron guns, and can operate stably for longer periods of time and provide higher current electron beams than cold field emission cathode electron guns. It has the following characteristics. However, due to its operating characteristics, in addition to the axial electron beam obtained from the tip of the electron emitting tip, a large amount of unnecessary thermoelectrons are emitted from the filament that heats the electron emitting tip. These unnecessary thermoelectrons collide with an anode located around the electron emitting chip and release the gas adsorbed and occluded by the anode. The emitted gas deteriorates the degree of vacuum around the electron emitting chip, and is simultaneously ionized and collides with the electron emitting chip. Eventually, a discharge occurs and the electron emitting chip is damaged. In order to solve such problems, a method is known in which the electron emission chip and the heating filament are covered with a control electrode (also known as a suppressor electrode, Schottky shield) to suppress the emission of thermionic electrons (Japanese Patent Application Laid-Open No. 49/1989). -38
No. 100). Conventionally, molybdenum steel has been used for this control electrode because it releases less gas (Bakorfret published by Ft!I Company).
THERMAL FIELD EMITTER0PER
ATINGINSTR1lCTIONS JANUAR
Y, 1987” (7) p. 2).
しかしながら、モリブデン鋼は、酸化されやすく、制御
電極は大気中で保管されている時に表面の酸化が進行す
る。そのため熱電界放射陰極電子銃を使用したときに上
記制御電極の酸化物表面から直接的、あるいは間接的に
多量のガス放出が行なわれ、電子放射特性を劣化させ、
あるいは、放電により電子放射チップを破損させたりす
るという問題があった。However, molybdenum steel is easily oxidized, and oxidation of the surface of the control electrode progresses when it is stored in the atmosphere. Therefore, when a thermal field emission cathode electron gun is used, a large amount of gas is released directly or indirectly from the oxide surface of the control electrode, which deteriorates the electron emission characteristics.
Alternatively, there is a problem that the electron emitting chip may be damaged due to discharge.
上記問題を解決するため、熱電界放射陰極電子銃の制御
電極は、大気中で酸化しにくく、１０−”〜１０−Ｉｏ
ｔｏｒｒの超高真空中でガス放出が少なく、そして、前
記超高真空中で動作させた時にも（該制御電極温度は約
２００℃に達するが）、ガス放出が少ないという特性を
兼備えていなければならない。In order to solve the above problem, the control electrode of the thermal field emission cathode electron gun is difficult to oxidize in the atmosphere, and the control electrode of the thermal field emission cathode electron gun is
It must have the characteristics of having little outgassing in an ultra-high vacuum of torr, and also having little outgassing even when operated in the ultra-high vacuum (although the control electrode temperature reaches about 200°C). Must be.
本発明はこの様な問題を解決し、安定で長寿命な熱電界
放射陰極電子銃を提供することを目的とする。The present invention aims to solve these problems and provide a stable and long-life thermal field emission cathode electron gun.
〔課題を解決するだめの手段〕
本発明者らは上記目的を達成するために、制御電極の材
質と酸化及びガス放出特性等について種々検討を行なっ
た結果、ステンレス鋼を制御電極として用いるという着
想を得、種々検討の結果、本発明を完成させるに至゛っ
た。[Means for Solving the Problem] In order to achieve the above object, the present inventors conducted various studies on the material of the control electrode and its oxidation and gas release characteristics, and as a result, they came up with the idea of using stainless steel as the control electrode. As a result of various studies, we have completed the present invention.
すなわち、本発明は、絶縁台に直接あるいは間接に固定
した電子放射チップを制御電極で覆い、該制御電極にあ
けられた穴から前記電子放射チップをのぞかせ、前記電
子放射チップより電子を放射させる熱電界放射陰極電子
銃において、前記制御電極がステンレス鋼からなること
を特徴とする熱電界放射陰極電子銃である。以下、本発
明について詳しく説明する。That is, in the present invention, an electron emission chip fixed directly or indirectly to an insulating stand is covered with a control electrode, the electron emission chip is exposed through a hole made in the control electrode, and the electron emission chip is heated to cause the electron emission chip to emit electrons. The field emission cathode electron gun is characterized in that the control electrode is made of stainless steel. The present invention will be explained in detail below.
本発明らの検討結果によればステンレス鋼の次の性質が
とくに熱電界放射陰極電子銃の制御電極に適合している
。すなわち、第１にステンレス鋼は極薄い（数１０人）
、シかも、ち密な酸化皮膜を表面に形成し、それ以上酸
化が進行しないので、酸化膜に吸着、あるいは吸蔵され
るガス量はモリブデン鋼に比べて極めて少ない。第２に
、ステンレス鋼は、真空中で数時間加熱処理（いわゆる
ベーキング）を行なえば、真空中でのガス放出量が非常
に少なくなる。According to the study results of the present inventors, the following properties of stainless steel are particularly suitable for the control electrode of a thermal field emission cathode electron gun. In other words, firstly, stainless steel is extremely thin (several tens of people).
However, since a dense oxide film is formed on the surface and oxidation does not proceed any further, the amount of gas adsorbed or occluded by the oxide film is extremely small compared to molybdenum steel. Second, if stainless steel is heat treated (so-called baking) in a vacuum for several hours, the amount of gas released in a vacuum becomes very small.
制御電極に用いる、ステンレス鋼の種類はオーステナイ
ト系ステンレス鋼、すなわちクロム、ニッケル、及び炭
素の含有量がそれぞれ１６〜２６％、６〜２２％、及び
０．２％以下のものが好ましい。The type of stainless steel used for the control electrode is preferably austenitic stainless steel, that is, one in which the contents of chromium, nickel, and carbon are 16 to 26%, 6 to 22%, and 0.2% or less, respectively.
なぜならば、制御電極は非磁性でなければならず、もし
、磁性が生じていた場合には、電子放射特性に悪影響を
与えるからである。磁性が生じることを避けるため、オ
ーステナイト系ステンレス鋼の中でも、特に低炭素含有
量（０，０８％以下）のものを選ぶことが望ましい。低
炭素オーステナイト系ステンレス鋼としては、５ＵＳ−
３０４，５ＵＳ−３１６，５ＵＳ−３１７、Ｓ Ｕ Ｓ
−３２１，５ＵＳ−３４７などがある。また、必要に応
じては消磁をするために、加工後に固溶化処理（約１１
００℃から約４００℃までに、急激に温度を下げる）を
行なうと良い。This is because the control electrode must be non-magnetic, and if magnetism were present, it would adversely affect the electron emission characteristics. In order to avoid magnetism, it is desirable to select an austenitic stainless steel with a particularly low carbon content (0.08% or less). As a low carbon austenitic stainless steel, 5US-
304,5US-316,5US-317, S.U.S.
-321, 5US-347, etc. In addition, in order to demagnetize if necessary, solid solution treatment (approximately 11
It is best to rapidly lower the temperature from 00°C to approximately 400°C.
ベーキングは１５０℃程度の温度で行なうことが望まし
い。１５０℃程度のベーキングを行なうことで、ステン
レス鋼表面からのガス放出量は、モリブデン鋼清浄面を
ベーキングした場合のそれと同程度となる。実際には、
熱電界放射陰極電子銃を有する装置を真空引きする場合
には、該装置全体として２００〜３００℃のベーキング
が行なわれるので、あらためて、制御電極のみをベーキ
ングする必要はない。It is desirable that baking be performed at a temperature of about 150°C. By baking at about 150° C., the amount of gas released from the stainless steel surface is comparable to that when baking a clean surface of molybdenum steel. in fact,
When a device having a thermal field emission cathode electron gun is evacuated, the entire device is baked at 200 to 300° C., so there is no need to bake only the control electrode.
制御電極の表面、特に陽極と対向する表面は、パフ研磨
などの手法を用いて鏡面仕上げにすることが望ましい。It is desirable that the surface of the control electrode, particularly the surface facing the anode, be mirror-finished using a technique such as puff polishing.
この仕上げを行なうことで、吸着ガス量を最少にするこ
とができ、また、放電の発生も抑えることができる。な
お、制御電極の形状はとくに限定がな〈従来知られてい
るものでよい。By performing this finishing, the amount of adsorbed gas can be minimized and the occurrence of electric discharge can also be suppressed. Note that the shape of the control electrode is not particularly limited, and may be any conventionally known shape.
モリブデン鋼及びステンレス鋼５ＵＳ−３０４とからな
る制御電極を用い、それぞれ熱電界放射陰極電子銃を作
製した。前記それぞれの制御電極の表面は、パフ研磨に
より鏡面仕上げとし、ジクロロエタン洗浄、水洗を施し
である。それぞれの該熱電界放射陰極を温度４０℃、湿
度８０％ＲＨの大気中にて保管したところ、モリブデン
鋼制御電極は、表面が薄茶色に変色し、酸化が進行して
いる様であったが、ステンレス鋼５ＵＳ−３０４を用い
た制御電極には変色が見うけられなかった。A thermal field emission cathode electron gun was fabricated using control electrodes made of molybdenum steel and stainless steel 5US-304. The surface of each of the control electrodes was polished to a mirror finish by puff polishing, and washed with dichloroethane and water. When each of the thermal field emission cathodes was stored in an atmosphere with a temperature of 40°C and a humidity of 80% RH, the surface of the molybdenum steel control electrode turned light brown and oxidation appeared to be progressing. No discoloration was observed in the control electrode made of stainless steel 5US-304.
その後、これらの熱電界放射陰極電子銃を真空装置に装
着し、排気したところ、第１表に示すとおり、それぞれ
の到達真空度はモリブデン鋼制御電極を用いた熱電界放
射陰極電子銃の場合は１．５〜２．４Ｘ １０−９ｔｏ
ｒｒであり、ステンレス鋼５ＵＳ−３０４の場合には０
．８〜１． ｌ Ｘ １０−９ｔｏｒｒであった。さら
に、この後、該熱電界放射陰極電子銃に−２，８〜３．
２ＫＶの高圧を印加して電子ビームを放射させたところ
、この動作時の真空度はモリブデン鋼を用いた場合は、
良くても９．５Ｘ１０−’ｔｏｒｒであり、３点中２点
は一時的な、大幅な真空度の劣化により、放電破損した
。一方、ステンレス鋼５ＵＳ−３０４を用いた場合には
、動作真空度は３．３〜４．８ Ｘ ｌ Ｏ−” ｔｏ
ｒｒであり、３点とも安定な電子ビーム放射が得られた
。After that, these thermal field emission cathode electron guns were attached to a vacuum device and evacuated. As shown in Table 1, the respective achieved vacuum degrees were as follows for the thermal field emission cathode electron guns using molybdenum steel control electrodes. 1.5~2.4X 10-9to
rr, and 0 for stainless steel 5US-304
．． 8-1. The pressure was 1×10 −9 torr. Furthermore, after this, -2,8 to 3.
When a high voltage of 2KV was applied and an electron beam was emitted, the degree of vacuum during this operation was as follows when molybdenum steel was used.
At best, it was 9.5X10-'torr, and two out of three points suffered discharge damage due to temporary and significant deterioration of the degree of vacuum. On the other hand, when stainless steel 5US-304 is used, the operating vacuum degree is 3.3 to 4.8
rr, and stable electron beam radiation was obtained at all three points.
第１表
〔発明の効果〕
本発明の、熱電界放射陰極電子銃は制御電極からのガス
放出が少なく、放電破損することなく安定な電子ビーム
の放射が行なえる。Table 1 [Effects of the Invention] The thermal field emission cathode electron gun of the present invention emits less gas from the control electrode and can stably emit an electron beam without being damaged by discharge.
Claims (1)
ップを制御電極で覆い、該制御電極にあけられた穴から
前記電子放射チップをのぞかせ、前記電子放射チップよ
り電子を放射させる熱電界放射陰極電子銃において、前
記制御電極がステンレス鋼からなることを特徴とする熱
電界放射陰極電子銃。(1) A thermal field emission cathode in which an electron emission chip fixed directly or indirectly to an insulating stand is covered with a control electrode, the electron emission chip is peeked through a hole made in the control electrode, and electrons are emitted from the electron emission chip. 1. A thermal field emission cathode electron gun, wherein the control electrode is made of stainless steel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63242436A JPH0294237A (en) | 1988-09-29 | 1988-09-29 | Thermal electric field emission cathode electron gun |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63242436A JPH0294237A (en) | 1988-09-29 | 1988-09-29 | Thermal electric field emission cathode electron gun |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0294237A true JPH0294237A (en) | 1990-04-05 |
Family
ID=17089064
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63242436A Pending JPH0294237A (en) | 1988-09-29 | 1988-09-29 | Thermal electric field emission cathode electron gun |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0294237A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5536944A (en) * | 1994-06-29 | 1996-07-16 | Denki Kagaku Kogyo Kabushiki Kaisha | Thermal field emmission electron gun |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5458345A (en) * | 1977-10-19 | 1979-05-11 | Hitachi Ltd | Electron gun |
| JPS5744949A (en) * | 1980-08-29 | 1982-03-13 | Jeol Ltd | Electron gun |
-
1988
- 1988-09-29 JP JP63242436A patent/JPH0294237A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5458345A (en) * | 1977-10-19 | 1979-05-11 | Hitachi Ltd | Electron gun |
| JPS5744949A (en) * | 1980-08-29 | 1982-03-13 | Jeol Ltd | Electron gun |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5536944A (en) * | 1994-06-29 | 1996-07-16 | Denki Kagaku Kogyo Kabushiki Kaisha | Thermal field emmission electron gun |
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