JPS61279039A - Liquid metal ion source structural body - Google Patents

Abstract

PURPOSE:To stabilize an ion beam, by providing a heat insulating part in such a manner that it encloses a storage part. CONSTITUTION:The structural body in the title is built up in such a manner that both sides of the bottom part of a needle like electrode 1 are held by conductive support members 5a, 5b from both sides through heat generating support members 4a, 4b, a storage part 2 which is enclosed by a heat insulating member 14 is provided near the needle like electrode 1, and storage part support members 3a, 3b which are fixed by their one ends being connected to the heat insulating member 14 and the other ends being connected to the electrically insulated parts close to the one portions of the conductive support members 5a, 5b. As a result, since positional variations of the top of the needle like electrode are eliminated and the storage part is heat-insulated, an ion beam can be stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a liquid metal ion source structure.

[Prior art and problems]

Various proposals have been made regarding liquid metal ion source structures.

For example, (1) there is a field evaporation type ion source structure using a hairpin type heater in which a needle-like member is fixed to a bent portion of the heater (Japanese Patent Application Laid-Open No. 114257/1983).

However, since this uses a hairpin type heater, when heated, the hairpin type heater is thermally deformed and the emitter position changes, making it impossible to obtain a stable ion beam.

An improved version of this is (2) a heat-generating support member,
Some are designed to support a reservoir of metal to be ionized.

To explain further, this is because a storage part that stores the metal to be ionized, an electrode with a needle-like tip to which liquid metal is supplied from the storage part, and a strong electric field formed at the tip of the needle-like electrode. and a support member that is thermally connected to the reservoir or the needle electrode and generates heat when energized, and the support member is formed of a substance that has poor affinity with the liquid metal. It consists of (
JP-A-58-35829).

However, when emitting ions using such a device, when the molten metal is energized, it wets the surface of the exothermic support member, which has a higher temperature than the reservoir and the needle electrode, and the resistance decreases. The disadvantage is that the temperature decreases, making it impossible to obtain uniform ions, and in extreme cases, heating becomes impossible and ions are no longer released.

[Means for solving problems]

The present inventor has conducted various studies on how to obtain a stable ion beam in the grasping type field evaporation type ion source structure described in (2) above, and has found that ionized substances do not creep into the heat-generating support member. By using this method, we have completed the invention of a stable and long-life field evaporation type liquid ion source structure.

That is, the present invention provides a liquid metal device that includes a storage section that holds an ionized substance, a needle-shaped electrode that penetrates the lower part of the storage section, and a lower end of the electrode that is held by a heat-generating support member to obtain a point-like ion beam through an electric field. This is a liquid metal ion source structure characterized in that an insulating heat-insulating section is provided to surround a storage section in the ion source structure.

The present invention will be further explained below with reference to the drawings.

1, 2, and 3 show embodiments of the present invention. FIG. 1 is a sectional view illustrating the entire liquid metal ion source structure, and FIGS. It is an explanatory view of a storage part, a heat generating support member, and a needle-like electrode part of an ion source structure.

First, as shown in FIG. 1, the liquid metal ion source structure of the present invention consists of a storage section 2 for an ionized substance 11, a needle electrode 1, and exothermic support members 4a and 4b. The storage portion 2 surrounded by the heat insulating material 14 is placed near the needle-like part of the needle-like electrode by gripping both sides of the bottom part with the conductive support members 5a and 5b via the heat-generating support members 4a and 4b. a storage part support member 3a, which has one end connected to the heat insulating part 14 and the other end connected to and fixed to an electrically insulated part close to a part of the conductive support members 5a, 5b; It is composed of 3b.

Further, to explain the structure of the liquid metal ion source according to the present invention, the ionizable substance is an alloy or an elemental metal having a melting point of 1400 or less.

The alloy is (1) an alloy containing at least one of B, P, and As, such as Ni-B and Ni-B.
-P, N i -BA s, Pd-N1-BSPt
-B etc. or a combination thereof, (2) SQ
An alloy containing at least one of L and Be, such as Au-8j, -Be, etc. (3) In addition, Go, S
b.

It is an alloy containing at least one of Cs, Kg, and Cd. Also, as single metals, Cs, Ga, In
', Sn.

Bi%Pb, 4%USGe, Au, etc.

The needle electrode 1 is made of a substance that is difficult to react with ionized substances and easily wetted, such as high melting point metals such as tungsten, tantalum, and molybdenum, borides such as titanium, zirconium, niobium, tantalum, chromium, tungsten, and molybdenum, A sintered body of carbide or nitride, or a single crystal thereof is processed into a thin columnar shape, and the tip is processed to have a radius of curvature of 1 to 2 μm by electrolytic polishing or mechanical polishing. As shown in FIG. 2, the storage section 2 is made of a high melting point metal such as tantalum that is easy to process and processed into a hollow columnar or prismatic shape.

In addition, as shown in Figure 3, tungsten, molybdenum,
A high melting point metal wire such as tantalum may be wound into a coil shape one or more times. According to this method, relatively large capacity reservoirs can be easily created. The heat insulating part 14 is made of an insulating material such as alumina, magnesia, steatite, quartz glass, etc., and is intended to keep the temperature of the molten material in the storage part. FIG. 2 shows a heat insulating part 14 having an inner diameter that allows the storage part 2 to be inserted snugly, and a groove formed around the outer periphery to which the thin wires of the storage part support members 3a and 3b can be wound and fixed, and a needle. 1 shows a cross section of the arrangement of a shaped electrode 1, an ionized substance 11, and a storage section 2. FIG. 3 shows an example of the storage section 2 in which a coiled metal wire is fixed inside the heat insulating section 14. Storage part 2 is made of high purity alumina cement, colloidal silica,
It may also be fixed to the reservoir support members 3a, 3b using an inorganic adhesive mainly composed of colloidal alumina or the like. The reservoir support members 3a, 3b are made of high melting point metal wires or strips such as tungsten, tantalum, or molybdenum.

Spot welding is sufficient for connection to the storage portion 2 and the vicinity of the conductive support members 5a, 5b, but electron beam welding may be used if necessary.

In the case of FIG. 3, the storage section 2 and storage section support members 3a, 3b
is good as a whole. By adjusting the lengths of the reservoir support members 3a and 3b, the distance between the reservoir 2 and the tip of the needle electrode 1 can be easily and arbitrarily changed.

The conductive support members 5a, 5b are connected to tie bars 12 fixed at both ends with nuts 8a, 8b via insulators 6a, 6b.
is fixed. Further, the conductive support members 5a and 5b are a coupling member 8a.

8b is connected to electrode terminals 9a and 9b.

The storage section support members 3a, 3b may be connected to either end of the tie bar 12 or to either of the nuts 7a, 7b as long as they are electrically insulated from the conductive members 5a, 5b.

〔Example〕

Next, an example of a liquid metal ion source according to the present invention will be described.

In the ion source with the structure shown in Figure 2, the cross section is 0.75
X0.75 Pus, prismatic Cr B2 with length between 3.0
Using a single crystal, the tip is mechanically polished to a cone angle of 30°.
It was processed into a needle-like electrode with a radius of curvature of 2 μm. Thickness 0.1mm
Process the Ta plate to have an inner diameter of 1.2 tm and a length of 1.
Make a cylinder with five cabinets, and make it with an inner diameter of 1°4+a and an outer diameter of 1.6
The bait was inserted into an alumina cylinder with a length of 1.5 strips, and a tungsten wire with a diameter of 0.2 mm was wound around the groove formed on the outside of the alumina cylinder to secure it, and both ends of the tungsten wire were tied with tie bars. Spot welding was carried out on both ends of 12.

The bottom side surface of the needle electrode 1 is equipped with a heater made of pyrolytic graphite (0.75w+XO,75mmXO,75
m). Pd4゜NI4゜B in the storage part
A 2° alloy was placed therein, and ion beam radiation was performed under a vacuum of 7×10 −7 Torv. Output voltage 3K”
A stable ion beam was obtained for 300 hours at i'. The stability of the ion beam at this time is 0.5%/ml
? After use, the ion source was taken out and observed, but no alloy was observed near the exothermic support members 4a, 4b and the exothermic support members 4a, 4b of the needle electrode 10. In addition, the storage section support members 3a and 3b and the storage section 2
A slight amount of alloy adhesion was observed near the connection with the
It did not affect the support of the storage section 2.

〔Effect of the invention〕

(1) According to the present invention, the lower side surface of the needle electrode is firmly fixed with the heat-generating support member, so that the position of the tip of the needle electrode does not change even when heated, and the storage portion is Since it is insulated, the supply of ionized material is constant, resulting in excellent ion beam stability.

(2) Since the storage part, needle electrode, and heat-generating support member are fixed independently, the size of the storage part can be changed arbitrarily, and even if the storage part is enlarged, the storage part support Since one end of the member is connected and fixed to a part far away from the needle electrode and the heat-generating support member, less heating power is required to heat the storage section.

(3) Since the storage section is separated from the exothermic support member and is provided with a protective member, the melted ionized substance does not get wet with the exothermic support member.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, and FIG.
FIGS. 2 and 3 are explanatory diagrams of the liquid metal ion source structure, and are explanatory diagrams of the needle electrode, storage section, and exothermic support member portion of the liquid metal ion source. Number 1 ・・・・・・・・・ Needle electrode 2 ・・・・
......Storage parts 3a, 3b...Storage part support members 4a, 4b...Exothermic support member 5a
, 5b... Conductive support members 6a, 6b...
...Insulators 7a, 7b...Nuts 8a, 8b...Coupling members 9a, 9b...Electrode terminal 10...Insulator 11・・・・・・・・・ Ionized substance 12 ・・・
・・・・・・ Tie bar 13 ・・・・・・・・・ Extracting electrode 14 ・・・・・・・・・ Heat insulation part patent applicant Denki Kagaku Kogyo Co., Ltd. Hada 2na Slag 37A

Claims (1)

[Claims] In a liquid metal ion source structure that includes a storage part that holds an ionized substance, a needle-shaped electrode that penetrates the lower part of the storage part, and a lower end of the electrode that is held by a heat-generating support member, a point-shaped ion beam is obtained through an electric field. A liquid metal ion source structure characterized in that an insulating heat-insulating part is provided to surround the part.