JPS5873948A - Ion gun - Google Patents

Abstract

PURPOSE:To obtain an ion gun which can safely produce field ions stably by providing a moving body which gives compressive breaking force to an ampoule installed in an ampoule-installation space under a vacuum condition, and moving the moving body from outside the ampoule so as to load the ion gun with a reactive metal without making the metal in contact with air. CONSTITUTION:A fine hole 10, until an ampoule 6 is broken, is opened and accelerates exhaustion of an ampoule-installation space 5, and blocked up by a downwardly moving pipe 8 as soon as the ampoule 6 is broken. The pipe 8 moves down until a moving shaft 26 is stopped by a stopper 28. By the process mentioned above, the loading of a liquid metal 2 is finished. Next, production of an ion beam is carried out. The liquid metal 2 flows out from a space 1c, which is formed between the capillary 1a and the needle 1d of an emitter part 1, due to electrostatic force, and reaches the pointed end of the needle 1d after flowing over the surface of the needle 1d. As a result, a conical projection called a tailor corn develops at the pointed end of the needle 1d according to the balance between the surface tension and the electrostatic force of the metal 2, and an ion beam is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ion gun that generates field ions from a highly reactive liquid metal using electrohydrodynamics (BHD).

As an ion gun for generating an ion beam in an ion microanalyzer, an ion gun that generates field ions using RID from liquid metal has been proposed. In this type of ion gun, cesium, etc., is highly reactive with air or moisture in the air, and liquid metals that are difficult to handle in the air can be safely stored inside the ion gun without reacting with the air. It is necessary to introduce

The reactive metals mentioned above are used in a vacuum-evacuated state and sealed in glass ampoules.
Until now, there has been no device that can safely load reactive metals without causing a reaction with air or the like.

This invention was made in view of the above points, and includes a moving body that applies a compressive breaking force under vacuum to the ampoule housed in the ampoule housing space, and is moved from the outside to bring it into contact with air. The object of the present invention is to provide an ion gun that can safely and stably generate field ions by loading a reactive metal into the ion gun without any problems.

The present invention includes an ampoule housing space that houses an evacuated reactive metal ampoule and is connected to an emitter, a means for evacuating the ampoule housing space, a moving body that applies a compressive breaking force to the ampoule, and an ampoule housing space that is connected to an emitter. This ion gun is characterized by having a mechanism for moving a forward movable body by rotating a telescopic operation unit provided outside the storage space.The present invention will be explained below with reference to the drawings. Fig. 1 is a vertical sectional view showing an ion gun according to an embodiment of the present invention, Fig. 2 is a partially enlarged view thereof, Fig. 3 is an enlarged view of section A in Fig. 2, and Fig. 4 is an operating state. FIG.

In the drawing, 1 is capillary/needle type +7)E
A part of the HD emitter, the details of which are shown in FIGS. 2 and 3, includes a capillary 1a forming a reservoir 2a of liquid metal 2, and a base 1b of this capillary 1a.
It consists of a tungsten needle 1d that is spot welded to the tip of the capillary 1a and protrudes outside the capillary with a gap 1c formed therebetween.

The emitter part 1 is fixed to the lower end of the container 4 by a cap nut 6 and communicates with the ampoule receiving space 5 of the container 4.

The ampoule storage space 5 contains an ampoule 6 sealed with liquid metal.
is held and housed in the ampoule boulder 7, and is pressed toward the ampoule breaking protrusion 9 by a moving pipe 8 that applies compressive breaking force. The moving pipe 8 is allowed to slide inside the container 4 while keeping it airtight, and is fixed to the ampoule boulder 7. An ampoule storage space 5 is provided on the side wall of the container 4.
A small hole 10 for vacuuming is provided, and the upper end is fixed to a 7 flange 11.

A heat shield plate 16 is provided at the tip of the frame 12 fixed to the 7 langes 11 so as to surround the capillary 1a, and a heater 14 is provided inside the heat shield plate 16. In the embodiment, the heater 14 uses a heater that heats with radiant heat rather than a resistance type heater, but it can also be heated by electron impact heating in which hot electrons generated from a tungsten wire or the like are accelerated and collided with each other, or by high-frequency heating using a highly conductive coil. It may be based on induction heating.

The flange 11 is the acceleration tube 1 placed on the base 15 in two stages.
6 and supported on a flange 17 fixed to 6. The interior of the acceleration tube 16 is an ion gun chamber 18, an extraction electrode 19 is supported between each acceleration tube 16, and a pore 18 is provided in the center facing the emitter part 1. Further, a ground electrode (cathode) 20 is provided opposite the extraction electrode 19 and supported by the base 15, and a pore 20a is provided in the center thereof coaxially with the pore 19a and the emitter part 1. Below the ground electrode 20, there is a lens barrel for forming an ion probe including a focusing lens/deflection system, etc., and an ion gun chamber 18.
Although an exhaust port for evacuating the air is provided, illustration thereof is omitted.

A casing 22 having a flange 21 is fixed to the flange 11, and a cylinder 26 is fixed to the 7 flange 21.
7 flange 24 having 7 flanges 24 are polymerized and fixed. A moving shaft 26 is slidably provided in the cylinder 26 and connected to the ampoule holder 7 by a coupling 25 so as to compensate for misalignment of the shaft, and is pressed upward by a spring 27. 28 is provided with a sliding groove 29.

A female thread 3o is provided at the center of the upper part of the moving shaft 26, and a male thread 31 is screwed into the female thread 3o. A rod 66 having a head 62 is provided at the top of the male thread 31, and a knob 64 is provided.
It is attached so that it can slide through the slide wall 65 of. A groove 66 is provided on the lower side of the head 62 and can be engaged with a protrusion 37 provided on the slide wall 35, and both constitute a clutch. The knob 64 is rotatably attached to the cylinder 26. Flange 2
A bellows 68 is provided between the moving shaft 260 and the moving shaft 260.

In the ion gun configured as described above, the ampoule 6 containing the reactive metal is attached to the ampoule holter 7 and accommodated in the ampoule storage space 5 of the container 4, and
7 and 21.24 are fixed. When the ion gun chamber 18 is at atmospheric pressure, the moving shaft 26 is pushed upward by the spring 27, and the groove 36 and the protrusion 67 are separated, so that the rotational force of the knob 64 is not transmitted to the male screw 31. It has become.

In this state, the ion gun chamber 18 is opened from the exhaust port (not shown).
When the vacuum is applied, the bellows 68 expands and the moving shaft 26
is lowered, and the groove 66 and the protrusion 37 are engaged, resulting in the state shown in FIG. At this stage, when the knob 64 is rotated while vacuuming, the rotational force is transferred from the protrusion 67 to the groove 36 and the head 3.
2 and the rod 66 to the male screw 31, and the moving shaft 26 descends.

As the moving shaft 26 descends, the moving knob 8 also descends, applying compressive force to the ampoule 6. In this case, since the opposite side of the ampoule 6 is supported by the protrusion 9, the concentrated stress is relieved in this part, the ampoule 6 is broken, and the liquid metal 2 sealed therein is released into the ampoule housing space 5 and the emitter part 1. Becomes capillary b. The pores 10 are open until the ampoule 6 is destroyed to facilitate exhaustion from the ampoule storage space 5, but when the ampoule 6 is destroyed, the pores 10 are quickly cut off by the descending moving pipe 8. The moving pipe 8 continues to descend until the moving shaft 26 is stopped by the stopper 28.

With the above steps, loading of the liquid metal 2 is completed, and the process moves on to generating an ion beam. To generate an ion beam, first, the heater 14 is energized to heat the liquid metal filled in the reservoir 2a4C of the emitter part 1. In this case, a temperature sensing means is provided in the capillary 1a of the emitter part 1, and heating is performed so that the temperature is always constant, and then an extraction voltage is applied between the emitter part 1 and the extraction electrode 19. When an accelerating voltage is applied between the ground electrode 20 and the needle 1d to form a strong electric field at the tip of the needle 1d, the liquid metal 2 flows out from the gap 1c between the capillary 1a of the emitter part 1 and the needle 1d due to electrostatic force, and the needle As shown in FIG. 4, a conical protrusion 2h called a tiller cone is generated from the surface of the liquid metal 20 due to the balance between surface tension and electrostatic force. arise. The electric field strength is extremely large at the tip of the protrusion 2b, and the electric field evaporates and ionizes the metal ions, resulting in an ion beam 39.

Ion beam 39 passing through the pore 19a of the extraction electrode 19
is further accelerated by the ground electrode 20 and sent from the pore 20a to the ion probe forming lens barrel υ (not shown).

The amount of liquid metal 2 loaded in the ampoule 6 can be used semi-permanently, but in order to reload it due to an operational error or the like, remove the 7-lunge 24 and perform the same operation as described above.

In the above embodiment, a □ screw is used as a mechanism for converting the rotational movement of the knob 64 into a linear movement of the moving shaft 26, but a cam or other mechanism may be used. Further, the clutch mechanism is not limited to that of the above embodiment, and other structures may be used.

□Moreover, although the movable pipe 8 and the protrusion 9 are provided as means for destroying the ampoule 6, other structures may be used.

Reactive metals that can be used in the present invention include cesium, gallium, gold, aluminum, and other metals. Although the above embodiment is applied to a capillary/needle type ion gun, it is also applicable to a needle type, capillary type, or other ion gun that generates field ions using EHD. Further, the present invention can be used as an ion microanalyzer and an ion gun for all other uses.

As described above, according to the present invention, a movable body that applies compressive breaking force under vacuum to the ampules housed in the ampoule housing space is provided, and the operation can be performed using an external rotational force, so that the operation can be performed easily. Reactive metals can be loaded safely and reliably without contact with air. Therefore, field ions can be generated safely and stably.

Further, by providing a clutch mechanism that transmits rotational force only under vacuum, it is possible to prevent the ampoule from breaking and to prevent the liquid metal from reacting with air or the like when air is present in the ion gun. Furthermore, the ampoule opens before breaking,
By providing an opening that is blocked after the ampoule is broken, air can be exhausted before the ampoule is broken, and evaporation of the liquid metal can be prevented after the ampoule is broken.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing an ion gun according to an embodiment of the present invention, FIG. 2 is a partially enlarged view of snow, and FIG. 3 is an A of FIG.
FIG. 4 is a partial enlarged view showing the operating state. 9. ,,,□,:. In each figure, the same reference numerals indicate the same parts, 1 is part of the emitter, 1a is the capillary, 1 is the emitter, 1 is the capillary, 2 is
is a liquid metal, 4 is a container, 5 is an ampoule storage space, 6 is an ampoule, 7 is an ampoule holder, 8 is a moving pipe, 9 is a protrusion, 10 is a pore, 11.17.21.24 is a flange, 13 is a heat Shielding plate, 14 heater, 15 base, 16
is the acceleration tube, 18 is the ion gun chamber, °19 is the extraction electrode, 20
is a ground electrode, 22 is a casing, 23 is a cylinder, 25
is a coupling, 26 is a moving shaft, 27 is a spring, 2
Reference numeral 8 is a strut horn ξ, 31 is a male screw, 34 is a knob, 36 is a groove, 37 is a protrusion, 38 is a rose, and 39 is an ion beam. Agent Patent Attorney Sei Yanagihara'1 Figure 3

Claims (1)

[Claims] (1) Contains an evacuated reactive metal ampoule;
and an ampoule housing space connected to the emitter, a means for evacuating the ampoule housing space, a movable body that applies a compressive breaking force to the ampoule, and an operating unit provided outside the ampoule housing space to rotate the ampoule housing space. (2) An ion gun characterized by comprising a mechanism for moving a movable body (2) A clutch mechanism for moving the movable body by rotation of an operating part only in a vacuum state Claim 1
(3) The ion gun according to claim 1 or 2, wherein the ampoule housing space is provided with a protrusion that applies concentrated stress to a part of the ampoule. (4) The ampoule housing space is provided with a projection that applies concentrated stress to a part of the ampoule. The mechanism for moving the moving body of the ion gun (5) according to any one of claims 1 to 3, wherein the ion gun is evacuated before the ampoule is evacuated and is shut off after the ampoule is broken. An ion gun according to any one of claims 1 to 4