JP3017997B2 - Field emission cathode - Google Patents
Field emission cathodeInfo
- Publication number
- JP3017997B2 JP3017997B2 JP26189290A JP26189290A JP3017997B2 JP 3017997 B2 JP3017997 B2 JP 3017997B2 JP 26189290 A JP26189290 A JP 26189290A JP 26189290 A JP26189290 A JP 26189290A JP 3017997 B2 JP3017997 B2 JP 3017997B2
- Authority
- JP
- Japan
- Prior art keywords
- cathode
- field emission
- cone
- silicon substrate
- cathode cone
- 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
Links
Landscapes
- Micromachines (AREA)
- Cold Cathode And The Manufacture (AREA)
Description
【産業上の利用分野】 本発明は、陽極との間に電界を印加して電子を放出さ
せる電界放出電極（別名、冷陰極）に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field emission electrode (also called a cold cathode) that emits electrons by applying an electric field between the anode and the anode.
従来、電界放出陰極は、半導体装置の製造と同様の微
細加工技術によって、第２図に示すように、導電性基板
としての高不純物濃度（低抵抗）のシリコン基板１上に
円錐形状のカソードコーン２を設けると共に、そのカソ
ードコーン２の少なくとも一部を囲むように絶縁層３を
設け、その絶縁層３の上面にカソードコーン２の先端部
分に臨むように放出電子流制御用のゲート電極４を設け
て構成されている。そして、カソードコーン２の材質と
して、従来では、モリブデンが用いられている（C.A.Sp
indt,I.Brodie,L.Humphrey,and E.R.Westerbeg Journal
of AppliedPysics,vol.47,No.12,p.5248）。2. Description of the Related Art Conventionally, as shown in FIG. 2, a field emission cathode is formed on a silicon substrate 1 having a high impurity concentration (low resistance) as a conductive substrate by a microfabrication technique similar to that for manufacturing a semiconductor device. 2, an insulating layer 3 is provided so as to surround at least a part of the cathode cone 2, and a gate electrode 4 for controlling the emission electron flow is provided on the upper surface of the insulating layer 3 so as to face the tip of the cathode cone 2. It is provided and configured. Molybdenum is conventionally used as the material of the cathode cone 2 (CASp
indt, I. Brodie, L. Humphrey, and ERWesterbeg Journal
of AppliedPysics, vol. 47, No. 12, p. 5248).
【発明が解決しようとする課題】 ところが、カソードコーンの材質としてのモリブデン
は、Sachtlerによる（Trans 301 Intern Vacuum Cong
r.,1965,vol.1,p.41）データから、気体吸着のし易い材
料であり、気体を吸着すると電界放出時にマイクロディ
スチャージを発生し、時間的に電流が変化するゆらぎを
惹起して放出電流を不安定にすることが知られている
（T.IEE Japan,Vol.110−A,No.6,'90 P.356）。 また、モリブデンによるカソードコーンでは、円錐基
部の直径が１μｍ以下と小さくなり、この電界放出陰極
をバイポーラもしくはMOS型のシリコンデバイス或はマ
イクロマシンと組み合せた構造に用いる際、シリコン基
板１との間の接触電気抵抗がかなり大きくなる。 この接触電気抵抗が大きくなると、電流を多く流す場
合にその接触電気抵抗部で電圧降下が発生するので、よ
り大きな電圧を印加しなければならなくなる。また、こ
のとき、電子放出の速度分布に関して、接触電気抵抗部
の影響による分布の拡大（電子の速度のバラツキの拡
大）が起こることも知られている（C.A.Spindt NASA−C
R−159570またはI.Brodie IEDM 89 p.521）。 そこで本発明は、カソードコーンについて改良を施し
て前記した問題を解決した電界放出陰極を提供せんとす
るものである。However, molybdenum as a material of the cathode cone is described by Sachtler (Trans 301 Intern Vacuum Cong
r., 1965, vol. 1, p. 41) According to the data, it is a material that easily adsorbs gas. When gas is adsorbed, micro-discharge occurs at the time of field emission, causing fluctuations in the current over time. It is known that the emission current is unstable (T. IEE Japan, Vol. 110-A, No. 6, '90 P. 356). In the case of a cathode cone made of molybdenum, the diameter of the base of the cone becomes as small as 1 μm or less. When this field emission cathode is used in a structure combined with a bipolar or MOS type silicon device or micromachine, the contact between the silicon substrate 1 The electric resistance becomes considerably large. When the contact electric resistance increases, a voltage drop occurs in the contact electric resistance portion when a large amount of current flows, so that a larger voltage must be applied. At this time, it is also known that the electron emission velocity distribution expands due to the influence of the contact electric resistance portion (expansion of electron velocity variation) (CASpindt NASA-C).
R-159570 or I. Brodie IEDM 89 p.521). Accordingly, the present invention is to provide a field emission cathode which solves the above-mentioned problem by improving the cathode cone.
このために第１の発明は、導電性基板の上にカソード
コーンを設け、該カソードコーンの少なくとも一部を囲
むように絶縁層を設け、該絶縁層の上に上記カソードコ
ーンの先端部分に臨むようにゲート電極を設けて構成し
た電界放出陰極において、上記カソードコーンの先端部
分を白金、パラジウム、イリジウム、ロジウムまたはそ
れらを含む合金で形成した。 第２の発明は、第１の発明において、上記導電性基板
をシリコン基板とし、該シリコン基板と上記カソードコ
ーンとの界面にシリサイド層を介在させて構成した。For this purpose, the first invention provides a cathode cone on a conductive substrate, an insulation layer surrounding at least a part of the cathode cone, and a front end portion of the cathode cone on the insulation layer. In the field emission cathode provided with the gate electrode as described above, the tip of the cathode cone was formed of platinum, palladium, iridium, rhodium or an alloy containing them. According to a second invention, in the first invention, the conductive substrate is a silicon substrate, and a silicide layer is interposed at an interface between the silicon substrate and the cathode cone.
本発明では、カソードコーンの先端部分が白金、パラ
ジウム、イリジウム、ロジウムまたはそれらを含む合金
で形成されるので、その部分の気体吸着が少なくなり、
放出電子が安定化する。また、カソードコーンとシリコ
ン基板との界面にシリサイト層が介在するので、その部
分の接触電気抵抗が少なくなり、電圧降下が低下して、
電子の速度分布の拡大が防止できる。In the present invention, since the tip portion of the cathode cone is formed of platinum, palladium, iridium, rhodium or an alloy containing them, gas adsorption of the portion is reduced,
The emitted electrons are stabilized. In addition, since the silicide layer is interposed at the interface between the cathode cone and the silicon substrate, the contact electric resistance at that portion is reduced, and the voltage drop is reduced.
The expansion of the electron velocity distribution can be prevented.
以下、本発明の実施例について説明する。第１図はそ
の一実施例の電界放出陰極の構造を示す断面図である。
第２図において説明したものと同一のものには同一の符
号を付した。 本実施例では、符号５で示す円錐形状のカソードコー
ンの先端部5aに白金属元素（白金、パラジウム、イリジ
ウム、ロジウムのいずれか、またはそれらを含む合金）
を用い、中間部5bに金（Au）等の導体を用い、底部5cを
上記と同様の白金属元素として、その底部5cとシリコン
基板１との界面をシリサイド化しそこにシリサイド層を
形成している。このシリサイド化はデポジション時の温
度（例えば100℃）で行なう。 上記先端部5aの白金属元素は、仕事関数が大きく電界
放出用の陰極としては適当でないと従来では考えられて
いたが、この白金属元素はモリブデンに比べて気体の吸
着熱が小さく、気体が吸着し難いという性質をもつ。す
なわち、第３図に示すように、O2、C2H4、N2、NH3、H2
のガスに対して、パラジウム（Pd）、ロジウム（Rh）、
イリジウム（Ir）、白金（Pt）はモリブデン（Mo）に比
べてその吸着熱が低い。 底部分5cとシリコン基板１とのシリサイド化された界
面（シリサイド層）は、高不順物濃度のシリコン基板に
対してそのシリサイドのバリアハイトが小さく、低接触
電気抵抗となるので、そこでの電圧降下を小さくするこ
とができる。 中間部5bは、底部5cのシリサイド部分が先端部5aまで
達しないようにする（達すると、抵抗が大きくなり融点
が低下し形状が経時変化する。）ためのものであり、シ
リサイド化しないような導体が使用されている。 以上から、真空中においてゲート電極４とカソードコ
ーン５の先端との間にバイアスを加え、同時にカソード
コーン５の先端と陽極との間に高電界を印加すると、電
子がカソードコーン５から陽極に向けて放出されるが、
その電子電流は安定化し、高電流時でもカソードコーン
５とシリコン基板１との間の接触電気抵抗による電圧降
下は小さくなり、電子の速度分布の拡大を防ぐことがで
きる。 実験では、パラジウムをカソードコーン５に用いた電
界放出陰極で、７×７アレイ（49個の電界放出電極群）
のものから、100μＡ程度の放出電流が得られており、
また白金を使用した場合には400μＡ以上の放出電流が
得られた。 なお、白金属元素としては、上記した白金、パラジウ
ム、イリジウム、ロジウムの他に、オスミニウム、ルテ
ニウムがあるが、これらは酸素に対して反応（酸化）し
易いので、カソードコーン用の材質としては適当でな
い。Hereinafter, examples of the present invention will be described. FIG. 1 is a sectional view showing the structure of the field emission cathode of the embodiment.
The same components as those described in FIG. 2 are denoted by the same reference numerals. In this embodiment, a white metal element (any of platinum, palladium, iridium, and rhodium, or an alloy containing them) is provided at the tip 5a of the conical cathode cone indicated by reference numeral 5.
And a conductor such as gold (Au) is used for the intermediate portion 5b, the bottom 5c is made of the same white metal element as described above, and the interface between the bottom 5c and the silicon substrate 1 is silicided to form a silicide layer there. I have. This silicidation is performed at the temperature at the time of deposition (for example, 100 ° C.). It has been conventionally thought that the white metal element at the tip 5a has a large work function and is not suitable as a cathode for field emission.However, this white metal element has a smaller heat of gas adsorption than molybdenum, and the It has the property of hardly adsorbing. That is, as shown in FIG. 3, O 2 , C 2 H 4 , N 2 , NH 3 , H 2
Palladium (Pd), rhodium (Rh),
Iridium (Ir) and platinum (Pt) have lower heats of adsorption than molybdenum (Mo). The silicidized interface (silicide layer) between the bottom portion 5c and the silicon substrate 1 has a small silicide barrier height and a low contact electric resistance with respect to a silicon substrate having a high impurity concentration, so that the voltage drop there is reduced. Can be smaller. The intermediate portion 5b is for preventing the silicide portion of the bottom portion 5c from reaching the tip portion 5a (when it reaches, the resistance increases, the melting point decreases, and the shape changes over time). Conductors are used. From the above, when a bias is applied between the gate electrode 4 and the tip of the cathode cone 5 in a vacuum and a high electric field is applied between the tip of the cathode cone 5 and the anode at the same time, electrons are directed from the cathode cone 5 to the anode. Is released,
The electron current is stabilized, and the voltage drop due to the contact electric resistance between the cathode cone 5 and the silicon substrate 1 is reduced even at a high current, so that it is possible to prevent the electron velocity distribution from expanding. In the experiment, a field emission cathode using palladium for the cathode cone 5 was a 7 × 7 array (49 field emission electrode groups).
The emission current of about 100μA was obtained from
When platinum was used, an emission current of 400 μA or more was obtained. As the white metal element, there are osmium and ruthenium in addition to the above-mentioned platinum, palladium, iridium and rhodium, but these are easily reacted (oxidized) with oxygen, so that they are suitable as materials for the cathode cone. Not.
以上のように本発明によれば、カソードコーンの先端
部分に白金、パラジウム、イリジウム、ロジウム又はそ
れらを含む合金を使用するので、気体吸着が少なく、放
出電流が安定化する。またシリコン基板に接する底部分
にシリサイド層を介在するので、その部分が低抵抗化
し、大電流放出時の電圧降下が少なく、電子放出の速度
分布の拡大を小さくすることができる。As described above, according to the present invention, since platinum, palladium, iridium, rhodium or an alloy containing them is used for the tip portion of the cathode cone, gas adsorption is small and emission current is stabilized. Further, since the silicide layer is interposed at the bottom portion in contact with the silicon substrate, the resistance is reduced at that portion, the voltage drop at the time of discharging a large current is small, and the expansion of the electron emission speed distribution can be reduced.
第１図は本発明の一実施例の電界放出陰極の断面図、第
２図は従来の電界放出陰極の断面図、第３図は各種材料
の気体との吸着熱と酸化物の生成熱の特性を示す図であ
る。 １……シリコン基板、２……カソードコーン、３……絶
縁層、４……ゲート電極、５……カソードコーン、5a…
…先端部、5b……中間部、5c……底部。1 is a cross-sectional view of a field emission cathode according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a conventional field emission cathode, and FIG. 3 is a graph showing heat of adsorption of various materials with gas and heat of formation of oxide. It is a figure showing a characteristic. DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2 ... Cathode cone, 3 ... Insulating layer, 4 ... Gate electrode, 5 ... Cathode cone, 5a ...
... tip, 5b ... middle, 5c ... bottom.
Claims (2)
該カソードコーンの少なくとも一部を囲むように絶縁層
を設け、該絶縁層の上に上記カソードコーンの先端部分
に臨むようにゲート電極を設けて構成した電界放出陰極
において、 上記カソードコーンの先端部分を白金、パラジウム、イ
リジウム、ロジウムまたはそれらを含む合金で形成した
ことを特徴とする電界放出陰極。1. A cathode cone is provided on a conductive substrate,
In a field emission cathode, an insulating layer is provided so as to surround at least a part of the cathode cone, and a gate electrode is provided on the insulating layer so as to face the tip of the cathode cone. Made of platinum, palladium, iridium, rhodium or an alloy containing them.
コン基板とし、該シリコン基板と上記カソードコーンと
の界面にシリサイド層を介在させたことを特徴とする電
界放出陰極。2. A field emission cathode according to claim 1, wherein said conductive substrate is a silicon substrate, and a silicide layer is interposed at an interface between said silicon substrate and said cathode cone.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26189290A JP3017997B2 (en) | 1990-09-28 | 1990-09-28 | Field emission cathode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26189290A JP3017997B2 (en) | 1990-09-28 | 1990-09-28 | Field emission cathode |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04138636A JPH04138636A (en) | 1992-05-13 |
| JP3017997B2 true JP3017997B2 (en) | 2000-03-13 |
Family
ID=17368217
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP26189290A Expired - Fee Related JP3017997B2 (en) | 1990-09-28 | 1990-09-28 | Field emission cathode |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3017997B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0547296A (en) * | 1991-08-14 | 1993-02-26 | Sharp Corp | Electric field emission type electron source and manufacture thereof |
| US5584739A (en) * | 1993-02-10 | 1996-12-17 | Futaba Denshi Kogyo K.K | Field emission element and process for manufacturing same |
| EP0681312B1 (en) * | 1993-11-24 | 2003-02-26 | TDK Corporation | Cold-cathode electron source element and method for producing the same |
| JP2985942B2 (en) * | 1996-05-28 | 1999-12-06 | 日本電気株式会社 | Field emission cold cathode device |
-
1990
- 1990-09-28 JP JP26189290A patent/JP3017997B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04138636A (en) | 1992-05-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |