JPS6264033A - Linear electron beam generator - Google Patents

Abstract

PURPOSE:To achieve linear beam even of high current while to uniform distribution of current density in the long side direction of beam by providing a take-out electrode having higher potential then the anode and a rectangular electron beam path hole in the way between the cathode and anode. CONSTITUTION:A control electrode 2 having a cathode 1 and an electron beam path hole 8 and a take-out electrode 3 having a rectangular electron beam path hole 9 applied with higher voltage than the anode 4 are arranged between the cathode 1 and anode 4. Consequently, asymmetric field is distributed in the electron beam path area to make linear the electron beam while to make uniform the current density distribution in long side of linear beam.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a linear electron beam generator, and particularly to a linear electron beam generating device for heat-treating the surface layer of a material such as a conductor, a semiconductor, or a dielectric with a linear electron beam. This invention relates to an electron beam generator.

rPrior art] As a method for extracting a linear electron beam, in an electron beam generator using a conventionally used sub-I-shaped filament 1, the cathode is made linear and the cathode is made into a rectangular shape. It is conceivable to use the control electrode in place of a control electrode having an electron beam passage hole.

In this case, the anode has a circular electron beam passage hole,
The optical system is also axially rotationally symmetrical.

[Problem that the invention seeks to solve]

At this time, when the beam current of the linear electron beam is small, for example, 10. , A, the current density distribution can be obtained in a substantially uniform state in the long side direction of the linear beam, and it can be sufficiently used for heat treatment and the like. However, depending on the heat treatment conditions,
A larger current, for example about 100 to 200 mA, is required. If you try to extract such a large current with the above configuration, it is difficult to extract the current itself, and even if you extract it, the beam shape will not be linear but elliptical, and However, there is a problem that the current density distribution is not uniform but becomes a Gaussian distribution.

The purpose of the present invention is to solve these conventional problems, and to create a linear beam with a linear beam shape even at large currents, and a current density distribution that is almost uniform in the long side direction of the linear beam. An object of the present invention is to provide a linear electron beam generating device.

[Means for Solving the Problems] The linear electron beam generator of the present invention includes a rectangular cathode, a control electrode having a rectangular hole surrounding the cathode, and a rectangular electron beam generator having a high potential with respect to the cathode. It is constructed by comprising an anode having an electron beam passage hole, and an extraction electrode located between the cathode and the anode, having a higher potential than the anode, and having a rectangular electron beam passage hole.

1 Effect] An extraction electrode is provided between the cathode and the anode, and by applying a voltage higher than the voltage applied to the anode, that is, the accelerating voltage, to this extraction electrode, a large current is extracted from the cathode, and an electron beam is extracted. By passing from the electrode to the anode, the electron beam is decelerated and can exit the anode at a speed corresponding to the accelerating voltage.

Therefore, even if the accelerating voltage is low, it is possible to extract a large current with a low accelerating voltage by increasing the extracting voltage. Furthermore, by making the electron beam passage holes of the extraction electrode and the anode rectangular, the electron beam passage area has a
An asymmetric electric field distribution is formed, which serves to keep the electron beam in a linear shape. The electron beam extracted from the anode is projected onto the material to be heated by an optical system.
If this optical system is sufficiently large compared to a linear electron beam and its aberrations are sufficiently small, there will be no particular problem.

[Example〕 Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a configuration diagram of an embodiment of the present invention.

As shown in FIG. 1, from the control electrode 2 and anode 4, which have a rectangular electron-emitting part, a control electrode 2 and an anode 4, each having a rectangular electron beam passing hole 8 that fits the electron-emitting part.
An extraction electrode 3 having a rectangular electron beam passage hole 9 to which a high voltage is applied is placed between the cathode 1 and the anode 4. At this time, the electron beam passage hole 9 of the extraction electrode has a rectangular shape, and its long side direction is aligned in the same direction as the long side direction of the cathode 1. In addition, for ease of understanding, control electrode 2
, respective plan views of the extraction electrodes 3 are shown at corresponding positions on the right side. At this time, in order to apply a voltage higher than the accelerating voltage to the extraction electrode 3 (in this embodiment, the accelerating voltage is 10 to 20
kv, the extraction voltage was set to 40 to 60 kv)) The electron beam emitted from the cathode 1 is determined by the extraction voltage, not the accelerating voltage. Therefore, for example, a large current of 18 On+A can be easily extracted from the cathode 1 with an extraction voltage of 60 kV. Furthermore, since the electron beam passage hole 9 of the extraction electrode 3 is rectangular, the shape of the electron beam is
Limited to rectangular shapes. Next, the electron beam extracted by the extraction electrode 3 is
If the acceleration voltage is kv, the speed will be decelerated to a voltage of 15 kv. Therefore, by adopting this configuration, 15k
Although the accelerating voltage is as low as v, a large current of 180a+^ can be easily extracted. Also, anode 4
As shown in the plan view on the right side, the electron beam passing hole 10 has a rectangular shape, and its long side direction is the same as the short side direction of the rectangular cathode 1 such that one crossover point of the rectangular cathode 1 It's aligned with the direction. This is different in the short side direction and the long side direction of the cathode 1, and because one crossover point in the short side direction is formed closer to the cathode 1 than in the long side direction, the position of the anode 4 is Since the width of the electron beam is larger on the short side of the cathode 1, the beam passage hole is shaped as shown in the plan view.

In this way, by making the electron beam passage holes of the extraction electrode 3 and the anode 4 rectangular and asymmetrical, the linear electron beam extracted from the cathode 1 is kept in a linear shape similar to the shape of the cathode. I was able to take it out. The electron beam that has passed through the anode 4 is projected onto the sample 7 by the lens coil 5. Even if the lens coil 5 is axially symmetrical, if its aberration is sufficiently small, the shape of the projected object will be linear. There is no problem even if there is. Further, the case where the linear electron beam is opened to the surface by the deflection coil 6 is similar to the case of the lens coil.

Therefore, a relatively large current (in this example, 1.80 mA at an accelerating voltage of 15 kv and an extraction voltage of 60 kv) can be extracted under a low accelerating voltage (10 to 20 kv), and the shape of the electron beam is linear. As a result of measurement using a Faraday cage, the beam length was approximately 5 mm, and the beam width was approximately 0.3 mm. Further, although the current density distribution varied by about 3 to 5% in the long side direction of the beam, a fairly uniform state could be achieved. Moreover, since only the beam current can be controlled without changing its shape by increasing or decreasing the extraction voltage, a beam with a uniform current density distribution can be obtained even with a small beam current.

(Effects of the Invention) As explained below, according to the linear electron beam generator of the present invention, a relatively large current of 50 to 200 I[l^] can be easily generated with a relatively small accelerating voltage of 10 to 20 kV. In addition, the shape of the electron beam can be kept linear,
In addition, the current can be controlled while keeping the current density distribution almost uniform, allowing uniform batch processing of large areas (beam length 3-5 mm), improving uniformity and efficiency of processing, and shortening processing time. .

[Brief explanation of drawings]

FIG. 1 is a diagram of one embodiment of the present invention. ]... Cathode, 2... Control electrode, 3... Extraction electrode, 4... Anode, 5... Lens coil,
... Deflection coil, 7... Sample, 8.9.10... Electronic beano\passing hole. 51/〉Zukosuru℃ ■ Graduation ・ 'I! I

Claims (1)

[Claims] a rectangular cathode, a control electrode having a rectangular hole surrounding the cathode, an anode having a high potential with respect to the cathode and having a rectangular electron beam passage hole, and a control electrode located between the cathode and the anode and having a rectangular hole surrounding the cathode; A linear electron beam generating device further comprising an extraction electrode having a high potential and having a rectangular electron beam passage hole.