JP3015572B2 - Linear cathode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear cathode in an electron gun used as a heat source for generating a metal vapor in a vacuum.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional electron gun. This electron gun evaporates a metal or the like in a vacuum by generating a long electron beam, and is hereinafter referred to as a linear electron gun.
That is, in this electron gun, a cathode 01 is arranged behind the anode 9 and the grid 8, and a cathode heating filament 7 is arranged behind the cathode 01. An electron emitting material 03 having a low work function is integrally fitted into the center of the cathode 01, and heat conduction and radiation are performed by the cathode heating filament 7 until a required emission current density is obtained only with the electron emitting material 03. And by electron bombardment. Anode 9 has cathode 0
A positive high voltage with respect to 1 is applied by the acceleration power supply 11,
The emitted thermoelectrons can be accelerated. A negative voltage is applied to the grid 8 by a grid power supply 10 to adjust the amount of electron beams and the light collecting property. Further, a uniform magnetic field B is formed in a direction perpendicular to the plane of the drawing.

Accordingly, the electron emission material 03 of the cathode 01
The thermoelectrons emitted from are accelerated by the anode 9 to become an electron beam 12, which is deflected 270 degrees by the action of the uniform magnetic field B. And electron beam 1
2 is focused and irradiated on a target (evaporation source) 13 in a crucible 14, whereby the target 13 evaporates and a metal vapor 16 is obtained. In FIG. 4, reference numeral 15 denotes a water cooling hole provided in the crucible 14, through which cooling water flows.

[0004]

FIGS. 3A and 3B are enlarged views of a cathode 01 used in a conventional linear electron gun.
As shown in FIGS. 2A and 2B, the cathode 01 has a concave portion formed in the center of a long cathode main body 04, and the electron-emitting material 03 is fitted into the concave portion. 03 is firmly connected by diffusion welding or brazing. Therefore, before heating, the cathode 01 is linear as shown in FIGS. 3A and 3B, but during heating as shown in FIGS. Due to the difference in thermal expansion of the main body 04, the main body 04 was thermally deformed to bend. When this amount of thermal deformation reaches the plastic region, a part of the amount of thermal deformation remains as a residual strain even during cooling as shown in FIGS. Therefore, when heating and cooling were repeated, the amount of deformation was accumulated and increased.

[0005] When the cathode is deformed as described above, the distance between the electrodes is different between the central portion and both ends, and there is a problem that the condensing property of the electron beam becomes non-uniform in the beam length direction. The present invention has been made in view of the above prior art, and has as its object to provide a linear cathode that can prevent thermal deformation of the cathode and maintain linearity even after repeated heating and cooling.

[0006]

In order to achieve the above object, the present invention provides an electron gun used as a heat source for evaporating metal or the like in a vacuum by generating a long electron beam. An electron emission material having a work function lower than that of the cathode body, processed into a shape that does not come off in the electron emission direction, inserted from the side surface, and a pin penetrating the cathode body and the electron emission material at the center of the cathode. I do.

[0007]

In the linear cathode of the present invention, the electron emission material does not escape from the cathode body in the electron emission direction.
Since it is inserted so as to be freely movable in the longitudinal direction, thermal deformation due to a difference in thermal expansion between the electron-emitting material and the cathode body during heating is allowed. Therefore, the linear cathode can always maintain linearity even when heating and cooling are repeated without thermal deformation. In addition, since the cathode body and the electron emission material are pinned at the center, thermal expansion occurs evenly in the left and right directions, and the emission of electrons is not biased.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. 1 and 2 show one embodiment of the present invention.
The linear electron gun shown in both figures deflects the electron beam by 270 degrees. That is, the linear cathode 1 is disposed behind the anode 9 and the grid 8, and the cathode heating filament 7 is disposed behind the linear cathode 1. An electron-emitting material 3 having a low work function is inserted in the center of the linear cathode 1, and heat conduction, radiation, and electrons are generated by the cathode heating filament 7 until a required radiant current density is obtained only with the electron-emitting material 3. Heated by impact method. A high positive voltage is applied to the anode 9 with respect to the cathode 1 by an acceleration power supply 11, and the emitted thermoelectrons can be accelerated. A negative voltage is applied to the grid 8 by a grid power supply 10 to adjust the amount of electron beams and the light collecting property. Further, a uniform magnetic field B is formed in a direction perpendicular to the plane of the drawing.

Therefore, the thermoelectrons emitted from the electron emission material 3 of the linear cathode 1 are accelerated by the anode 9 to become an electron beam 12, and the electron beam 12 is deflected 270 degrees by the action of the uniform magnetic field B. The electron beam 12 is condensed and irradiated on a target (evaporation source) 13 in the crucible 14, whereby the target 13 evaporates and a metal vapor 16 is obtained. Here, the linear cathode 1
2 (a) and 2 (b) show specific examples. As shown in FIG. 1, the linear cathode 1 has a concave portion formed in the center of a cathode main body 4 and an electron emission material 3 is inserted into the concave portion from the side. The shape of the concave portion of the cathode main body 4 and the shape of the corresponding electron-emitting material 3 are the same as those of a so-called dovetail groove, and the electron-emitting material 3 does not escape in the electron emission direction. As described above, since the electron emission material 3 and the cathode main body 4 are not integrally fastened but can move to the left and right, thermal deformation due to a difference in thermal expansion between the electron emission material 3 and the cathode main body 4 is allowed. Will be done. However, the pin 5 is driven into the center of the electron emitting material 3 and the cathode main body 4 so that the electron emitting material 3 does not fall out of the cathode main body 4.

As shown in FIG. 2 (e), two holes are provided in the bottom of the cathode main body 4 in the longitudinal direction so that the slide pin 2 is inserted into these through holes.
The cathode 14 is held by supporting both ends of the slide pin 2 with the cathode holder 6. In the linear electron gun of this embodiment having the above configuration, uniform light condensing properties are obtained at a position deflected by 270 degrees, and high-quality vapor deposition and the like can be performed at low cost by improving operability and evaporation efficiency. . In particular, since the linear cathode 1 does not lose heat and does not lose its linearity even when heating and cooling are repeated, there is an advantage that the cathode life is shortened. Further, since there is no problem of thermal deformation, it is possible to realize a longer linear cathode and linear electron gun, thereby reducing the equipment cost by reducing the electron gun. In addition, although the thermal deformation is allowed, the electron emission material 3 is fixed by driving the pin 5 at the center thereof, so that the emission of the electrons is not deviated right and left.

Although the linear cathode 1 shown in the above embodiment has a flat surface in the electron emission direction, the linear cathode of the present invention is not limited to this. For example, FIG. 2 (c) (d)
In order to obtain an electron beam longer than the cathode length, a surface in the electron emission direction may be an arcuate curved surface like a linear cathode 1 'shown in FIG. In the above embodiment, the method of fixing the electron emitting material 3 and the cathode main body 4 is by fitting in a dovetail shape. However, if thermal deformation can be tolerated, the method shown in FIGS. As shown in ()), trapezoidal fitting, step-like fitting, or arc-shaped fitting may be used.

The material of the cathode body 4 is a high melting point material such as tungsten or molybdenum, and the material of the electron emitting material 3 is tantalum, LaB ₆ , B
Various electron emission materials such as aW can be used.

[0013]

As described above in detail with reference to the embodiments, the present invention allows thermal deformation between the cathode main body and the electron-emitting material. , Do not lose linearity. For this reason, the condensing property of the electron beam is always uniform in the longitudinal direction.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a linear electron gun according to one embodiment of the present invention.

FIG. 2A is a front view showing a specific example of a linear cathode, FIG. 2B is a side view of the linear cathode shown in FIG.
(c) is a front view showing another example of the linear cathode, FIG. (d) is a side view of the linear cathode shown in FIG. (c), and FIG.
(a) is a perspective view of a linear cathode, and (f), (g), and (h) are side views of modified examples of the linear cathode.

FIG. 3A is a front view of a linear cathode before heating,
FIG. 2B is a side view of the linear cathode of FIG.
Is a front view of the linear cathode during heating, and FIG.
(E) is a front view of the linear cathode during cooling, and (f) is a side view of the linear cathode shown in (e) of FIG.

FIG. 4 is a configuration diagram of a conventional linear electron gun.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Linear cathode 2 Slide pin 3 Electron emission material 4 Cathode main body 5 Pin 6 Cathode holder 7 Cathode heating filament 8 Grid 9 Anode 10 Grid power supply 11 Acceleration power supply 12 Electron beam 13 Target 14 Crucible 15 Cooling hole 16 Metal vapor 01 Cathode 03 Electron emitting material 04 Cathode body

Continued on the front page (72) Inventor Takamasa Nakamura 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Mitsubishi Heavy Industries, Ltd. Hiroshima Works (72) Inventor Shigeo Konno 3-1-2 Musashino, Akishima-shi, Tokyo Sun Inside the Electronics Co., Ltd. (72) Inventor Toru Takashima 3-1-2 Musashino, Akishima-shi, Tokyo Japan Electronics Co., Ltd. (56) References JP-A-5-205676 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01J 37/06-37/07 C23C 14/30

Claims (1)

(57) [Claims] In an electron gun used as a heat source for evaporating metal or the like in a vacuum by generating a long electron beam, an electron emitting material having a work function lower than that of a cathode body is provided at a central portion of the cathode. A linear cathode processed into a shape that does not come off in the direction, inserted from the side, and a pin penetrating the cathode body and the electron emission material at the center of the cathode.