JP4094994B2 - Electron source equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electron source apparatus that stably lifts the rotation center of an electron beam when the material to be irradiated is irradiated with an electron beam by rotating the electron beam by about 270 degrees.
[0002]
[Prior art]
The electrons emitted from the heated filament are accelerated and drawn out, rotated by about 180 degrees by a magnetic field, and turned into an electron beam spot by a lens action to irradiate the material to be melted in the crucible, while in the middle of the electron beam path. The electron beam spot is scanned in a plane (scanning in the X and Y directions) with the X scan coil and the Y scan coil arranged, and the predetermined area of the material to be dissolved is heated almost uniformly by the energy of the electron beam. There is an electron source device that melts and evaporates, and vapor-deposits on a substrate disposed on the opposite surface.
[0003]
Conventionally, with this electron source device, the upper surface of the crucible is positioned substantially equal to or lower than the upper surface on the electron gun side, and the irradiation of the electron beam to the irradiated material in the crucible is realized substantially perpendicularly.
・ In order to prevent direct radiant heat from the crucible from coming to the electron gun side, the material evaporated from the irradiated material in the crucible is deposited (attached) on the electron gun side, contaminates and charges, and the electron beam becomes unstable. In order to avoid this problem, there is a technique in which a pole piece that lifts the magnetic field from the permanent magnet that rotates the electron beam about 270 degrees upward is provided above the electron gun and the center of rotation of the electron beam is lifted upward. .
[0004]
[Problems to be solved by the invention]
In the case of an electron source device in which a pole piece (soft iron) is provided on the upper side of the electron gun and the center of rotation of the electron beam is lifted upward by the technique described above, as a result, the upper surface of the crucible is substantially the same as the upper surface on the electron gun side. There is an advantage that it can be the same or downward, but the position of the electron beam spot that irradiates and heats the irradiated material in the crucible moves due to use, and it is not always possible to scan almost the same area in a plane and shift A phenomenon has occurred. While various experiments for pursuing the cause of the shift of the electron beam spot were repeated, a disk-like material of Si02 was placed in the crucible as the material to be irradiated, and the acceleration voltage of the electron beam was 8 KV, 400 mA (3. As a result of evaporating by heating the electron beam under the condition of 90 SEC at 2 KW), the pole piece temperature was raised to 80 to 85 ° C. ・ Zr02 disk-shaped material was put as the irradiated material, and the acceleration voltage of the electron beam was 8 KV, 900 mA. It was confirmed that the temperature of the pole piece was raised to 200 ° C. or higher (thermolabel burnout up to 90 ° C.) as a result of vapor deposition by heating with an electron beam under conditions of 150 SEC at (7.2 KW). For this reason, a measure for reducing the shift of the electron beam spot in the crucible with the passage of time has been devised without the influence of the fact.
[0005]
In order to solve these problems, the present invention provides an electron beam with a pole piece, lifts the center of rotation of the electron beam by a magnetic field upward, and rotates it by about 270 degrees to be the same as or below the upper surface on the electron gun side. The purpose is to solve the phenomenon that the electron beam spot shifts over time when a predetermined area is planarly scanned with a scan coil while irradiating the surface of the material to be irradiated in the crucible arranged in the direction from the almost vertical direction. It is said.
[0006]
[Means for Solving the Problems]
Means for solving the problem will be described with reference to FIG.
In FIG. 1, a filament 1 is energized and heated and emits an electron beam 2.
[0007]
The electron beam 2 is an electron beam emitted from the heated filament 1 and accelerated. Here, a magnetic field generated by a permanent magnet (not shown) is lifted upward by a pole piece. In this state, the material to be irradiated in the crucible 4 is irradiated and heated approximately vertically by rotating about 270 degrees while the center of rotation C is lifted upward.
[0008]
The pole piece 3 lifts the magnetic field distribution generated by a permanent magnet (not shown) upward and lifts the rotation center of the electron beam 2 upward.
The cover 31 covers the pole piece 3, takes out the radiant heat from the crucible 4 or the material to be irradiated melted in the crucible 4, and prevents the deterioration of the magnetic characteristics accompanying the temperature rise of the pole piece 3, thereby preventing the electron beam spot. This is to prevent the shift.
[0009]
The crucible 4 is for putting a material to be irradiated, melting the material to be irradiated with a spot of an electron beam, and depositing it on a substrate (not shown) arranged opposite to the material.
[0010]
Next, the structure and its operation will be described.
The electron beam 2 emitted from the filament 1 and accelerated is rotated about 270 degrees by a magnetic field distribution lifted by a pole piece 3 in which a magnetic field from a permanent magnet (not shown) is arranged in the upper direction of the filament 1. In a state in which the surface of the material to be irradiated in the crucible 4 arranged in the same or lower direction as the upper surface of the laser beam is substantially vertical and the center is irradiated, the scan coil (X, Y) 5 (see FIG. 2) (not shown) Surface scanning is performed to uniformly heat and dissolve, and vapor deposition is performed on a substrate disposed oppositely (not shown). At this time, the side of the pole piece 3 facing the crucible 4 is covered with at least a cover 31 to extract the radiant heat from the crucible 4 (or the material to be irradiated in the crucible 4) to the outside, thereby suppressing the temperature rise of the pole piece 3. The position of the electron beam spot that irradiates the irradiated material is prevented by preventing the deterioration of the magnetic characteristics.
[0011]
Here, copper is used as the material of the cover 31.
Further, the temperature rise of the cover 31 due to radiant heat is cooled by circulating a liquid or cooling by a heat pipe.
[0012]
Accordingly, the electron beam 1 is rotated about 270 degrees with the magnetic field distribution lifted by the pole piece 3 to irradiate the surface of the material to be irradiated in the crucible 4 from the substantially vertical direction, and the scan coil 5 performs plane scanning in a predetermined area. The upper surface of the crucible 4 is positioned in the same or lower direction as the upper surface on the electron gun side, the heat radiation from the crucible 4 arrives and is not heated, and the evaporant arrives on the electron gun side and deposits to contaminate and charge. Under the condition that the electron beam does not become unstable, the side facing the crucible 4 of the pole piece 3 is covered with the cover 31 to prevent the temperature rise due to the radiant heat of the pole piece 3 to prevent the deterioration of the magnetic characteristics. The shift of the position of the electron beam spot in the crucible 4 can be eliminated.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments and operations of the present invention will be described in detail sequentially with reference to FIGS.
[0014]
FIG. 1 is an explanatory diagram of the present invention.
1A shows a front view (outline), and FIG. 1B shows a view of the inside of the crucible 4 from the top. Here, the arrangement positions and paths of the filament 1 and the electron beam 2 are all stored in a container (chamber) that is evacuated to prevent the filament 1 from being oxidized and consumed, or the electron beam 2 can be easily ( For the most part, the surface of the material to be irradiated in the crucible 4 is reached, and further, a voltage (for example, 10 KV) for accelerating the electron beam emitted from the filament 1 is not discharged.
[0015]
In FIG. 1, a filament 1 is energized and heated to emit an electron beam 2.
The electron beam 2 is an electron beam emitted from the heated filament 1 and accelerated. Here, a magnetic field generated by a permanent magnet (not shown) is converted to a magnetic field distribution upward by a pole piece 3. In the state where the center of rotation C is lifted up and rotated upward, it is rotated by about 270 degrees to irradiate the material to be irradiated in the crucible 4 almost vertically and heat it.
[0016]
The pole piece 3 is made of a soft magnetic material that lifts the magnetic field distribution generated by a permanent magnet (not shown) upward and lifts the rotation center C of the electron beam 2 upward.
[0017]
The cover 31 covers the pole piece 3, absorbs (partially reflects) the radiant heat from the crucible 4 or the melted irradiated material in the crucible 4, extracts the absorbed heat to the outside, and increases the temperature of the pole piece 3. This is to prevent the shift of the electron beam spot by preventing the deterioration of the magnetic characteristics accompanying the above. As shown in FIGS. 2 and 3 to be described later, the cover 31 is made of thermally conductive copper or the like, and is cooled by circulating a liquid (for example, water) so that it can be further cooled inside. Furthermore, a heat pipe may be attached to release the heat of the cover 31 to the outside.
[0018]
The crucible 4 is for putting a material to be irradiated, melting the material to be irradiated with a spot of an electron beam, and depositing it on a substrate (not shown) arranged opposite to the material. Here, the pole piece 3 is covered with a cover 31, and the radiant heat from the crucible 4 (or the material to be irradiated and melted in the crucible 4) is taken out to suppress the temperature rise of the pole piece 3 to suppress the pole piece 3. The deterioration of the magnetic properties of the piece 3 is prevented to prevent the rotation center C and the like from being shifted, and the center of the irradiated material in the crucible 4 is always irradiated so as not to shift (see FIG. 1B). ). Note that a predetermined region (for example, 40 mmφ) is uniformly formed by a scan coil (X, Y) 5 (see FIG. 2) not shown in the state in which the center of the irradiated material in the crucible 4 is vertically irradiated with an electron beam spot. Planar scanning is performed.
[0019]
here,
(1) (solid line) of the electron beam is an example of the path of the electron beam spot before being affected by the radiant heat. As shown in FIG. 1 (b), almost all of the irradiated material in the crucible 4 The state of illuminating the center is shown.
[0020]
(2) (dotted line) of the electron beam is an example of the path of the conventional electron beam spot after being affected by the radiant heat, and as shown in FIG. It shows a state where the spot size is shifted from the center of the material and the spot size is greatly shifted. Thus, in the state without the conventional cover 31, the pole piece 3 is heated by the radiant heat from the crucible 4 (or the material to be irradiated inside) and the temperature rises (about 200 ° C. or more), and the magnetic characteristics deteriorate. As a result, the magnetic field distribution was shifted, and as a result, the electron beam spot position in the crucible 4 was shifted as shown in FIG. The cover 31 is provided so that the path as in the electron beam of (1) is left without a shift so that the electron beam spot is always irradiated almost at the center of the solid line in FIG. Is.
[0021]
FIG. 2 shows a perspective view (outline) of the present invention. This is an outline of the actual creation based on the configuration of FIG.
In FIG. 2, a pole piece heat countermeasure jig cover 31 shows a specific example of the cover 31 of FIG. 1 described above. Here, the pole piece heat countermeasure jig cover 31 is made of copper so as to cover the pole piece 3 as shown in the figure, The radiant heat from the crucible 4 (or the material to be irradiated in the crucible 4) is received and extracted to the outside, and the temperature rise of the pole piece 3 of the soft magnetic material inside is suppressed. As a result, the path of the electron beam 2 is shown in FIG. The state of 1) is always maintained and the center of the crucible 4 is always maintained in the state irradiated with the electron beam spot. Note that the surface of the irradiated material is uniformly scanned by the scan coil (X, Y) 5 in a state where the electron beam spot is always irradiated at the substantially center, so that the inside of the region is uniformly heated.
[0022]
Here, it can be considered that the state in which the dotted electron beam spot in FIG. 1B is shifted from the center is adjusted so that a bias current is supplied to the scan coil (X, Y) 5 and irradiated to the center. When the center of the material to be irradiated in the crucible 4 is irradiated through a path that is deflected at the center position of the scan coil (X, Y) 5 and bent along the dotted line in FIG.
・ The incident angle to the irradiated material becomes almost oblique from the vertical and the irradiation condition changes (the irradiation condition changes due to the oblique incidence), and
There is a problem that the irradiation condition is changed by moving to the center position while the electron beam spot size remains large as in the case of the dotted line in FIG.
There is a disadvantage that it is not practical. That is, the scan coil (X, Y) 5 cannot deflect the dotted electron beam spot in FIG. 1B to the solid electron beam spot (the position, size, and electron beam spot of the electron beam spot are irradiated). (It is impossible to satisfy the three irradiation conditions that the angle of incidence on the material is almost vertical.) (Adjusting the bias current to the scan coil (X, Y) 4 only allows adjustment of the position, the other two cannot be adjusted) is).
[0023]
FIG. 3 shows a perspective view of the present invention. This shows an example of a perspective view after the electron gun portion of FIG. 2 is completely assembled. Here, the pole piece 3 is covered with the pole piece heat countermeasure jig cover 3 and completely accommodated therein, and the heating by the radiant heat from the crucible 4 (or the irradiated material in the crucible 4) not shown in the figure is completely performed. It is possible to prevent the deterioration of the magnetic characteristics by suppressing the temperature rise, and to maintain the electron beam spot so as to always irradiate the substantially center of the irradiated material in the crucible 4 from the substantially vertical direction. Then, in a state where the electron beam spot irradiates almost the center of the irradiated material substantially vertically, the scan coil (X, Y) 5 uniformly scans the inside of the predetermined area, and the inside of the predetermined area. It is possible to uniformly melt by heating with an electron beam and to deposit on a substrate (not shown) arranged opposite to the substrate.
[0024]
In addition, the copper pole piece heat countermeasure jig cover 31 shown in FIG. 3 of the present invention is provided, and is the same as described in the section of [Problems to be solved by the invention]. As a result of depositing the material and evaporating by heating the electron beam under the condition of 90 SEC at an electron beam acceleration voltage of 8 KV, 400 mA (3.2 KW), the pole piece temperature is 50 ° C. or less. As a result of depositing materials and evaporating by electron beam heating under conditions of 150 SEC with an acceleration voltage of electron beam of 8 KV and 900 mA (7.2 KW), the temperature of the pole piece can be suppressed to 55 to 60 ° C. It was possible to maintain the electron beam spot of solid line (1) in b).
[0025]
【The invention's effect】
As described above, according to the present invention, the electron beam 1 is rotated by about 270 degrees with the magnetic field distribution lifted by the pole piece 3 to irradiate the irradiated material surface in the crucible 4 from the substantially vertical direction. 5, a predetermined area is scanned in a plane, the upper surface of the crucible 4 is positioned in the same or lower direction as the upper surface on the electron gun side, the heat radiation from the crucible 4 arrives and is not heated, and the evaporated material is moved to the electron gun side. The temperature of the pole piece 3 due to radiant heat is covered by covering the side facing the crucible 4 of the pole piece 3 with the cover 31 in a state where the electron beam 2 does not become unstable by being deposited and contaminated and charged. It was possible to prevent the magnetic characteristics from deteriorating by suppressing the increase, and to eliminate the shift of the position of the electron beam spot in the crucible 4.
[0026]
As a result, even if the irradiated material in the crucible 4 is repeatedly heated from the beginning of heating to the end of heating, the irradiated material can always be scanned in plane under the same irradiation conditions and the uniform heating condition can be maintained. It is possible to repeatedly form a uniform and highly reproducible deposited film on a substrate (not shown) arranged, and it is possible to provide an electron source device having extremely high reliability and good stability.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of the present invention.
FIG. 2 is a perspective view (outline) of the present invention.
FIG. 3 is a perspective view of the present invention.
[Explanation of symbols]
1: Filament 2: Electron beam 3: Pole piece 31: Cover (pole piece heat countermeasure jig cover)
4: Crucible 5: Scan coil (X, Y)
C: Center of rotation

Claims (3)

A magnet for rotating an electron beam emitted from an electron source and accelerated by a magnetic field by 180 degrees or more to irradiate an irradiated material from a substantially vertical direction;
The Lift the magnetic field distribution from the magnet disposed in the direction on the electron source in the upward lifting the rotation center of the electron beam in the upward direction, provided on opposite sides of the path of the electron beam, magnetic from the magnet Pole pieces connected with materials ,
A deflection coil that generates a scanning magnetic field that scans within a predetermined region a position where an electron beam spot rotated by a magnetic field distribution lifted upward by the pole piece irradiates from a substantially vertical direction of the irradiated material;
Covers at least the side of the pole piece facing the irradiated material, takes in the radiant heat from the irradiated material and draws it out, reduces the temperature rise of the pole piece due to the radiant heat, and increases the temperature of the pole piece An electron source device comprising: a thermally conductive cover for preventing shift of the electron beam spot due to deterioration of magnetic characteristics. 2. The electron source device according to claim 1, wherein copper is used as a material for the cover. 3. The electron source device according to claim 1, wherein the temperature rise of the cover due to the radiant heat is cooled by circulating a liquid or cooling by a heat pipe.

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