JP3170300B2 - High voltage / low current electron beam irradiation system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention aims at realizing uniform irradiation of a desired region on a substrate or the like with an electron beam by modifying the electron beam irradiation apparatus.

[0002]

2. Description of the Related Art Recently, a surface modification of a metal or alloy has been carried out by irradiating the surface of the metal or alloy with an electron beam having a small beam diameter generated at a high voltage and a low current in a dot shape or a line shape. Attempts have been made to develop new functional materials.

Means for modifying the surface of metals and alloys include laser irradiation, plasma irradiation and mechanical methods in addition to electron beam irradiation. In particular, electron beam irradiation requires the use of a high vacuum. Despite some handicap, the irradiation area is small compared to the above method, and the beam can penetrate deeply in the thickness direction of the irradiation target, and the scanning and swinging of the beam is easy and the irradiation work is fast. It has many advantages such as being able to be applied to large industrial materials, and having good thermal efficiency. In the surface modification for functional materials such as oriented silicon steel sheets, the above-described electron beam irradiation is used. Was a very effective means.

[0004]

In applying the electron beam irradiation technique, for example, a high-speed continuous vacuum apparatus using an air-to-air method must be developed so that a mass-produced steel sheet can be continuously processed. In addition, in such irradiation technology, it is also necessary to further reduce the beam diameter of the electron beam generated at high voltage and low current and obtain a beam with a deeper penetration depth. Development of a device capable of irradiating, or development of a device capable of irradiating uniformly, regularly and quickly over the width and / or longitudinal direction of a steel plate to be irradiated, and establishment of a scanning method remain as important issues.

Here, the above-mentioned high-speed continuous vacuum apparatus is disclosed in, for example, JP-A-64-65265.
As for an apparatus capable of obtaining an electron beam having a small beam and a large penetration depth, as disclosed in Japanese Patent Application No. 63-268316, the apparatus has already reached the stage of industrialization. However, a sufficient device which can uniformly and quickly irradiate the electron beam uniformly in the width direction or the length direction of the steel plate has not been obtained yet.

[0006] As a technique relating to this point, the present inventors have previously conducted irradiation over the width direction of the steel sheet while appropriately correcting the focal length of the beam so that the beam intensity is always the same even when the irradiation area of the electron beam changes. (Hereinafter referred to as the dynamic focus method), and proposed a method for producing a low iron loss unidirectional silicon steel sheet by subdividing the magnetic domain structure of the steel sheet to further improve the product characteristics (Japanese Patent Application No. − 2
68316).

The above technique is of a type in which a current flowing through a converging coil is controlled so that an accurate beam focus is achieved in accordance with a position where an electron beam is irradiated. The irradiation intensity of the electron beam varies depending on the irradiation position. The product characteristics were significantly improved compared to the conventional method.

However, there is a disadvantage that it is very difficult to control the current amplification when performing rapid beam irradiation because of the followability of the deflection frequency in the deflection coil that controls the deflection of the electron beam. In order to enable simple control using the dynamic focus method, the electron beam converging coil includes at least two types of converging coils: a converging coil of a current control type and a converging coil of a voltage control type. Although an irradiation device (see Japanese Patent Application No. 2-145492) has been proposed, it is difficult to uniformly irradiate the electron beam from the center to the end in the width direction of the steel plate with this device as well (the center in the width direction). Even if the part has a round beam shape, it becomes elliptical as it goes to the end), but at present, there is no effective means yet. In particular, when irradiating an electron beam on the surface of a unidirectional silicon steel sheet to subdivide magnetic domains,
It is important that the waveform of the electron beam is sharp and strong, and that the background is small in order to reduce the influence of the electron beam irradiation on the matrix. A new device that avoids the above-mentioned problems in electron beam irradiation using the dynamic focus method and can quickly and uniformly irradiate an electron beam generated at a high voltage onto an irradiation target, such as a substrate. It is an object of the present invention to make a proposal.

[0009]

According to the present invention, there is provided an electron beam generating section for emitting an electron beam, a converging coil for converging the electron beam emitted from the electron beam generating section, and a predetermined coil for converging the electron beam. In an electron beam irradiation apparatus having a deflection coil for irradiating an area, the convergence coil includes at least two types of convergence coils of a current control type and a voltage control type. A high-voltage / low-current type electron beam irradiation apparatus, wherein a Sting Mator for correcting astigmatism is arranged between the converging coil arrangement area and the deflection coil arrangement area. In the present invention, the cooling slit can be arranged particularly on the entrance side of the focusing coil.

FIG. 1 shows an example of a high-voltage / low-current type wide-angle deflection electron beam irradiation apparatus according to the present invention.
In the figure, reference numeral 1 denotes a casing provided with exhaust ports 1a and 1b to form a vacuum chamber, and 2 denotes an electron beam generator for emitting an electron beam B. The electron beam generator 2 includes a high-voltage insulator 2a and an electron An electron gun 2b for emitting electrons and an anode 2c for accelerating the electrons emitted from the electron gun 2b,
Column valve 2 for always keeping the electron beam generator at high vacuum
d and an alignment coil 2e. Reference numeral 3 denotes a converging coil for converging the electron beam B, for example, comprising a first coil 3a and a second coil 3b. The first coil 3a and the second coil One of them is a current control type, and the other is a voltage control type. Reference numeral 4 denotes a deflection coil which changes the traveling direction of the electron beam B converged by the converging coil 3 to irradiate a predetermined area of the substrate K with irradiation light. The Stingmatol 5 has a 4-pole, 8-pole or 16-pole type. However, in order to efficiently make the beam circular, the Stingmatol 5 has a 8-pole configuration.
The polar version applies. FIG. 2 schematically shows a Stingmatol 5 which is an 8-pole type.

FIG. 3 shows an electron beam irradiation apparatus having the structure shown in FIG. 1 above, which is useful for reducing the background and increasing the intensity of the electron beam B on the input side of the focusing coil 3. An example in which a water-cooled slit 6 (a one-step aperture) is arranged is shown. Here, in the present invention, 200-500K
An electron beam is generated under a high voltage of about V and a low current of 0.5 to 5 mA.

[0012]

According to the present invention, the electron beam irradiation apparatus includes:
A sting matol for correcting the astigmatism of the electron beam, or a sting matol and a cooling slit are arranged, and the focusing coil 3 has a coil 3a of a current control type and a coil 3b of a voltage control type.
In the beam irradiation on the substrate K immediately below the electron beam generator 2 (see point P on the substrate K in FIG. 1), the focal length hardly changes, so the current flowing through the coil 3a by the current control of the amplification amplifier is controlled. In the beam irradiation over both side regions of the substrate K, the variation caused by the deflection of the beam B is adjusted by applying a current to the coil 3b by controlling the voltage of the amplification amplifier. By using the combined magnetic field in (3), it is possible to irradiate a uniform electron beam having a beam shape with rapid and equal beam intensity over a wide range.

The converging coil 3 is not limited to the case where one coil of the current control type and one coil of the voltage control type are arranged, respectively.
The installation number can be increased as needed.

FIGS. 4 (a), 4 (b) and 4 (c)
This is a comparison between the beam intensity and the shape at the time of electron beam irradiation when Sting Mator is arranged in the electron beam irradiation apparatus. When the device according to the present invention is applied to irradiate an electron beam, the beam intensity and the shape are uniform at the center and the end in the width direction of the substrate K as shown in FIG. As shown in FIG. 4B, in the case of the conventional electron beam irradiation apparatus (without StingMator), the beam intensity and shape are extremely different between the center and the end in the width direction of the substrate K. As shown in c),
Although it can be seen that the device to which the dynamic focus method is simply applied (without Sting Mator arrangement) has some improvement, the beam intensity and shape are slightly different between the center and the end of the substrate K in the width direction.

Here, in the present invention, the sting matol 5 is arranged between the installation area of the converging coil 3 and the installation area of the deflection coil 4, because the beam is focused at the position where the beam is focused. This is because controlling the beam shape is more effective.

FIG. 5A, FIG. 5B, and FIG.
FIG. 4 is a diagram comparing the beam shapes of electron beams when a slit is arranged in an electron beam irradiation device. FIG.
(A) shows the beam shape when no slit is arranged in the electron beam irradiation device. In this case, the background is large and the beam is large. FIG.
(B) and FIG. 5 (c) show beam shapes when slits are arranged. In any case, the background can be made smaller than when no slits are arranged. However, in the case of FIG. 5B, since the slit as shown in FIG. 6A is applied, the beam intensity becomes small, and does not match the purpose of use. For this reason, it is desirable that the tip of the slit be tapered as shown in FIG. 6B or FIG. 6C so as to have a beam shape as shown in FIG. 5C.

When a slit is provided, it is necessary to adopt a structure capable of water cooling in order to prevent a rise in temperature at the tip.

[0018]

EXAMPLES Example-1 C: 0.033 wt% (hereinafter simply referred to as%), Mn: 0.35%,
Applied to a cold-rolled steel sheet having a thickness of 0.7 mm containing P: 0.013% and S: 0.012%, an apparatus having the configuration shown in FIG. 1 above is applied, under the conditions of acceleration voltage: 175 KV, acceleration current: 1.12 mA. Then, the trace state of the electron beam at that time was investigated. As a result, the difference between the electron beam shape at the center and the end in the width direction of the steel sheet is within 25%, the penetration depth of the electron beam (electron beam intensity) is within 20%,
It was confirmed that it was almost uniform over the entire width of the plate. Further, the deep drawability and the paintability of the steel sheet were also examined, and the steel sheet was uniform over the width direction of the steel sheet and showed good characteristics.

Example 2 The composition of a steel sheet having an insulating coating mainly composed of phosphate and colloidal silica was C = 0.001% and Si = 3.25.
%, Mn = 0.071%, Se = 0.001%, Mo = 0.013%, Sb =
An electron beam is applied to a 0.023% grain-oriented silicon steel sheet under the conditions of an acceleration voltage of 225 KV and an acceleration current of 1.1 mA by applying the apparatus having the configuration shown in FIG. Then, the iron loss values of the central part and the end part of the steel sheet after irradiation were measured.

As a result, W _17/50 is 0.78 at the center of the plate.
W / Kg At the edge of the plate, W _17/50 was 0.79 W / Kg, and it was confirmed that there was no significant change in quality.

Example 3 The composition of a steel sheet having an insulating coating mainly composed of phosphate and colloidal silica was C = 0.001% and Si = 3.
36%, Al = 0.001%, S = 0.001%, Cu = 0.08%,
An apparatus having the configuration shown in FIG. 3 above was applied to a unidirectional silicon steel sheet having Sn = 0.02% and irradiated with an electron beam under the conditions of an acceleration voltage: 225 KV and an acceleration current: 1.0 mA. Then, the iron loss values of the central part and the end part of the steel sheet after irradiation were measured. As a result, W _17/50 was as good as 0.78 W / Kg at both the center and the end of the plate, and the waveform of the electron beam was sharp as shown in FIG.

[0022]

As described above, according to the present invention, in the electron beam irradiation useful for the surface modification of metals and alloys, the electron beam can be quickly and uniformly irradiated over a wide range, so that the product quality can be improved and the productivity can be improved. Can be expected to be further improved.

[0023]

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a configuration of an electron beam device according to the present invention.

FIG. 2 is a diagram showing a schematic diagram of stingmatol.

FIG. 3 is a diagram showing another example of the device according to the present invention.

FIG. 4 is a diagram showing a beam intensity and a beam shape of an electron beam.

FIG. 5 is a diagram showing a beam shape of an electron beam.

FIG. 6 is a diagram showing a cross section of a slit arranged in the electron beam irradiation device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casing 1a, 1b Exhaust port 2 Electron beam generation part 2a High-pressure insulator 2b Electron gun 2c Anode 2d Column valve 2e Alignment coil 3 Convergence coil 4 Deflection coil 5 Stingmator 6 Cooling slit B Electron beam K substrate P Substrate width center point

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI H01J 37/141 H01J 37/141 Z 37/153 37/153 Z (72) Inventor Masaaki Kawanami 5-chome, Shiba 5-chome, Minato-ku, Tokyo No. 1 Inside NEC Corporation (56) References JP-A-2-40910 (JP, A) JP-A 57-112455 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 37/317 B23K 15/00 C21D 1/09 H01J 37/06 H01J 37/141 H01J 37/153

Claims (2)

(57) [Claims] An electron beam generator for emitting an electron beam;
An electron beam irradiation apparatus comprising: a converging coil for converging an electron beam emitted from the electron beam generating unit; and a deflection coil for irradiating a predetermined region with the electron beam converged by the converging coil. It is composed of at least two types of focusing coils, a focusing coil of the form and a focusing coil of the form of voltage control, and the astigmatism of the electron beam from the arrangement area of the focusing coil to the arrangement area of the deflection coil. A high-voltage, low-current electron beam irradiation apparatus characterized by disposing a sting matol for correcting the temperature. 2. The apparatus according to claim 1, wherein a water-cooling slit is arranged on an entrance side of the focusing coil.