JP5514595B2 - Electron beam irradiation device - Google Patents

Description

  The present invention relates to an electron beam irradiation apparatus, an electron beam irradiation region detection method, and an electron beam irradiation method, and more particularly to a technical field in which an electron beam is irradiated to dissolve, evaporate, sublime, and the like.

  Currently, a high-power electron beam irradiation apparatus that can irradiate an object to be irradiated with a relatively high energy electron beam to dissolve, evaporate, sublimate, etc. is mainly used for vacuum deposition and vacuum dissolution purification.

  Here, the high-power electron beam is energy of several kW to several tens of kW, current is in ampere order, output is several tens of watts to thousands kW, or 1 kW to 1,000 kW, or several tens kW to several thousand kW It is an electron beam having the above output.

The conventional high-power electron beam irradiation device has a relatively large vacuum chamber with a volume of 1 m ³ or more, a vacuum exhaust device that evacuates the vacuum chamber, an electron gun that emits an electron beam into the vacuum chamber, And an irradiation material container for holding the metal to be used. Here, the irradiation material container is a water-cooled hearth and is usually made of copper having good heat conduction.

  The target metal in vacuum melting and refining is an active metal such as titanium, a vacuum material such as stainless steel, and a high melting point metal such as molybdenum and tantalum, and the target metal in vacuum deposition is aluminum, titanium, copper or the like. Recently, vacuum melting purification of silicon has also been performed for solar cells. In an evacuated vacuum chamber, these irradiation objects are irradiated with an electron beam from an electron gun and heated to perform purification and vapor deposition.

  Here, the electron beam emitted from the electron gun into the vacuum chamber has an increased beam diameter due to repulsion between electrons due to Coulomb force when the amount of current increases. Also, the beam diameter changes due to the action of converging the beam diameter of the electron beam by the ions generated by the electrons themselves, depending on the pressure in the vacuum chamber.

  When the beam diameter of the electron beam on the irradiation object, that is, the size of the irradiation area irradiated with the electron beam of the irradiation object changes, the current density of the irradiation area changes and the power density changes. The irradiation condition of the electron beam to the object will change.

Changes in the beam diameter due to the above factors have made it difficult to maintain stable electron beam irradiation conditions when actually using an electron beam for purification and vapor deposition.
In particular, in order to keep the film formation rate in vacuum deposition constant, it is necessary to control the power density of the irradiated region. However, the beam diameter may change during irradiation due to the above factors. It is necessary to monitor the beam diameter with time. In addition, it is necessary to feed back the result to an electron gun irradiation control system (for example, the current value of the electron beam or the lens coil current of the electron gun) and to make the current density of the electron beam or the beam diameter of the electron beam constant. .

However, when the electron beam becomes high power, a wide range of the irradiation surface of the irradiation object emits light strongly, so that there is a problem that the size of the irradiation region cannot be monitored with visible light.
Further, in a method of measuring current with a movable Faraday cup or metal, which is generally used in the case of an electron beam with a low power of several watts or less, tungsten (W) having a high melting point is used for the beam irradiation portion. Even so, the irradiated portion melts immediately when irradiated with a high-power electron beam, so the beam diameter of the high-power electron beam could not be monitored.

As a realistic method, there is a method of irradiating a metal plate or the like with an electron beam at a medium output level smaller than high power and measuring a dissolved trace. Conventionally, the beam diameter of the electron beam has been generally obtained by this method. . However, it cannot be said that the dissolution mark correctly reflects the beam diameter of the electron beam. In addition, this method has a problem that it is impossible to measure the beam diameter under irradiation conditions when actually irradiating a high-power electron beam, and it is impossible to measure on-time.
In other words, detecting the size of the irradiated area when irradiating an irradiation object with a high-power electron beam has become an important issue, but a suitable method for solving this problem has been found so far. It wasn't.

JP 11-217667 A

  The present invention was created to solve the above-described disadvantages of the prior art, and its purpose is to irradiate the size of the irradiation region of the irradiation object or the beam diameter of the electron beam during irradiation of the high-power electron beam. It is in providing the electron beam irradiation apparatus which can detect.

In order to solve the above problems, the present invention has a vacuum chamber, a vacuum exhaust device that evacuates the vacuum chamber, and an electron gun configured to emit an electron beam into the vacuum chamber, An electron beam irradiation apparatus configured to irradiate an irradiation object disposed in the vacuum chamber with an electron beam from the electron gun to heat the irradiation object, wherein the irradiation object has a surface on the surface of the irradiation object. When an area irradiated with an electron beam and emitting X-rays is an irradiation area, the X-ray emitted from the irradiation area is disposed at a position where the X-ray is incident, and the size of the irradiation area is detected from the incident X-ray. possess the X-ray detection unit, and a X-ray imaging optical unit for forming an image of the irradiated region from the released the X-ray to the X-ray detection portion from the irradiated region, the said irradiation object The X-rays reach the X-ray imaging optical unit between the X-ray imaging optical unit and the X-ray imaging optical unit. However, an electron beam irradiation apparatus in which a filter device that attenuates the amount of vapor that is emitted from the heated irradiation object and reaches the X-ray imaging optical unit is disposed, and the filter device includes the vapor First and second rotating plates for shielding particles, first and second rotating shafts fixed perpendicularly to the first and second rotating plates, and the first and second rotating shafts. The first and second rotating plates have first and second rotating devices that rotate around the central axis of the first and second rotating shafts together with the first and second rotating plates. Are provided with first and second openings through which the vapor particles pass, and when the first and second rotating plates are rotated at different speeds by the first and second rotating devices, The first and second openings face each other at a position crossing the flight path of the X-ray and the steam. When the first and second openings face each other at a position crossing the flight path between the X-rays and the steam, the steam passing through the first opening is It is an electron beam irradiation apparatus comprised so that it might collide and shield with shielding parts other than said 2nd opening part of a 2nd rotating plate .
The present invention is an electron beam irradiation apparatus, an electron beam irradiation apparatus having a control device for controlling a beam diameter of the electron beam based on the size of the irradiated area in which the X-ray detection unit has detected.
The present invention is an electron beam irradiation apparatus, wherein the X-ray imaging optical unit includes a shielding plate that shields the X-ray, and the shielding plate allows the X-ray to pass through the X-ray detection unit. The electron beam irradiation apparatus is configured to form an image of the irradiation region on the X-ray detection unit from the X-rays having a small needle hole and passing through the needle hole.
The present invention is an electron beam irradiation apparatus, wherein the X-ray imaging optical unit includes a concave mirror that reflects the X-ray, and the irradiation region from the X-ray reflected by the concave mirror to the X-ray detection unit. It is an electron beam irradiation apparatus comprised so that the image of this may be formed .

  In the present invention, X-rays generated by electron beam irradiation are used. X-rays can be detected separately from visible light, and X-rays are emitted only from the portion irradiated with the electron beam on the irradiation target, so that the beam diameter of the electron beam can be monitored with high accuracy on time.

  It becomes possible to detect the size of the irradiation area of the irradiation object during irradiation of the high-power electron beam, and by feeding back the result to the irradiation control system of the electron gun, the power density of the irradiation area is made constant. It becomes possible to keep. The application field of high-power electron guns can be expanded by improving the accuracy of power density control.

  By keeping the power density of the electron beam irradiation region constant, the film formation rate of the vacuum vapor deposition apparatus using the electron beam can be kept constant, and a thin film product with good quality can be produced. For example, it can contribute to quality improvement of high storage media such as film capacitors and magnetic tapes, and optical application films such as heat ray blocking films.

  In the metal vacuum melting and refining apparatus, the power density in the irradiated region is accurately controlled, so that a high-quality metal such as high-purity titanium (Ti), tantalum (Ta) or high-purity crystalline silicon for solar cells ( Si) and the like can be produced.

The internal block diagram of the 1st example of the electron beam irradiation apparatus which is this invention Internal structure of electron gun Schematic configuration diagram of first example of X-ray detection device and filter device The top view for demonstrating the rotating plate of the 1st example of a filter apparatus Schematic diagram for explaining a pinhole type X-ray imaging optical unit Schematic diagram for explaining a mirror type X-ray imaging optical unit Schematic configuration diagram of second example of X-ray detection device and filter device Schematic configuration diagram of third example of X-ray detection device and filter device Schematic configuration diagram of fourth example of X-ray detection device and filter device The internal block diagram of the 2nd example of the electron beam irradiation apparatus which is this invention

<Structure of first example of electron beam irradiation apparatus>
The structure of the first example of the electron beam irradiation apparatus according to the present invention will be described.
FIG. 1 shows an internal configuration diagram of the electron beam irradiation apparatus 10.
The electron beam irradiation device 10 includes a vacuum chamber 11 and a vacuum exhaust device 13.
The vacuum exhaust device 13 is connected to the vacuum chamber 11 and configured to evacuate the vacuum chamber 11.

A concave irradiation material container 50 is disposed in the vacuum chamber 11. The irradiation material container 50 is disposed at the bottom of the vacuum chamber 11 with the opening facing upward, and is configured to hold the irradiation object 60 inside.
The electron beam irradiation apparatus 10 includes an electron gun 30 and an electron gun power source 40 that are configured to emit an electron beam.

FIG. 2 shows a schematic configuration diagram of the electron gun 30 and the electron gun power source 40.
The electron gun 30 has a bottomed cylindrical casing 31 provided with a muzzle 114 at one end.
Inside the casing 31, a gun chamber 110, a connection path 111, an intermediate chamber 112, and a discharge path 113 are provided in this order from the bottom of the casing 31 toward the muzzle 114 on the central axis.

A vacuum exhaust unit (not shown) is connected to each of the gun chamber 110 and the intermediate chamber 112, and the vacuum exhaust unit is configured so that each chamber 110, 112 can be evacuated. The connection path 111 is formed so that the inner periphery is smaller than the gun chamber 110 and the intermediate chamber 112, and is configured to connect the inside of the gun chamber 110 and the inside of the intermediate chamber 112. Therefore, the connection path 111 between the gun chamber 110 and the intermediate chamber 112 is connected. And has a differential exhaust structure. A partition valve 39 is disposed inside the connection path 111.
The interior of the intermediate chamber 112 is connected to the muzzle 114 via the discharge path 113.

Hereinafter, the gun chamber 110 side of the casing 31 is referred to as upstream, and the opposite muzzle 114 side is referred to as downstream.
In the gun chamber 110, a filament 32, a cathode 33, a Wehnelt 34, and an anode 35 are arranged in this order from upstream to downstream on the central axis of the casing 31.
A filament power supply 41 is electrically connected to the filament 32. The filament power source 41 is configured to heat the filament 32 by passing a current through the filament 32.

  A cathode heating power source 42 is electrically connected to the filament 32 and the cathode 33. The cathode heating power source 42 is configured to be able to apply a voltage between the filament 32 and the cathode 33 so that the potential of the cathode 33 becomes positive with respect to the filament 32.

The Wehnelt 34 is formed in a bottomless cylindrical shape having a larger inner circumference than the cathode 33, and is directed so that its own central axis coincides with the central axis of the casing 31. The Wehnelt 34 is electrically connected to the cathode 33.
The anode 35 is formed in a bottomless cylindrical shape, and is directed so that its center axis coincides with the center axis of the housing 31. The anode 35 is electrically connected to the housing 31.

  A high voltage power supply 43 is electrically connected to the casing 31 and the cathode 33. The high voltage power supply 43 is configured to be able to apply a voltage between the casing 31 and the cathode 33 so that the potential of the cathode 33 is negative with respect to the potential of the casing 31, that is, the potential of the anode 35.

Downstream of the anode 35, a first lens 36, a second lens 37, and a swing coil 38 are arranged in this order along the central axis of the housing 31.
Here, the first lens 36 is disposed outside the connection path 111 so as to surround the connection path 111, and the second lens 37 is disposed outside the discharge path 113 so as to surround the discharge path 113.

  A lens power supply 44 is electrically connected to each of the first and second lenses 36 and 37. The lens power supply 44 is configured to allow current to flow through the first and second lenses 36 and 37 to form magnetic fields in the connection path 111 and the emission path 113, respectively.

  The swing coil 38 is disposed so as to surround the muzzle 114 outside the discharge path 113. A coil power supply 45 is electrically connected to the swing coil 38. The coil power supply 45 is configured to allow a current to flow through the oscillating coil 38 so as to form a magnetic field in the trajectory of the electron beam located inside the muzzle 114.

A magnetic field controller (not shown) is connected to the coil power supply 45. The magnetic field control device is configured to change the current supplied from the coil power supply 45 to the oscillating coil 38 to control the direction and magnitude of the magnetic field formed in the trajectory of the electron beam.
When the power supply device of the electron gun 30 is referred to as an electron gun power supply 40, the electron gun power supply 40 includes a filament power supply 41, a cathode heating power supply 42, a high voltage power supply 43, a lens power supply 44, and a coil power supply 45.

Here, the electron gun 30 is hermetically inserted into the side wall of the vacuum chamber 11 with the muzzle 114 facing the irradiation object 60 on the irradiation material container 50.
When electric power is supplied from the electron gun power source 40 to the electron gun 30, the electron gun 30 emits an electron beam from the muzzle 114 into the vacuum chamber 11 and irradiates the irradiation object 60 on the irradiation material container 50 with the electron beam. It is configured as follows.

  X-rays (characteristic X-rays and white X-rays) are emitted from the portion irradiated with the electron beam on the surface of the irradiation object 60. Here, the characteristic X-rays are X-rays emitted from atoms on the surface of the irradiation object 60 that are excited by being irradiated with an electron beam, and the white X-rays are electrons of an electron beam damped on the surface of the irradiation object 60. X-rays emitted from.

Hereinafter, a region where an electron beam on the surface of the irradiation object 60 is irradiated and X-rays are emitted is referred to as an irradiation region.
An X-ray detection apparatus 20 is disposed at a position where X-rays emitted from the irradiation region are incident.
FIG. 3 shows a schematic configuration diagram of the X-ray detection device 20 together with a first example of a filter device 70 described later.

  The X-ray detection apparatus 20 has a detection unit container 21 made of a material that blocks X-rays. An X-ray detection unit 24 is disposed inside the detection unit container 21, and an X-ray detection unit power source 25 is electrically connected to the X-ray detection unit 24.

  Since the energy of the electron beam in this embodiment is about several keV to 40 keV as will be described later, the energy of the X-ray emitted from the irradiation object 60 irradiated with the electron beam is in the same range. As the X-ray detector 24, a detector having sensitivity to X-rays having energy in this range is used.

Here, a two-dimensional detector (CCD (Charge Coupled Device), MOS (Metal on Silicon) type imaging device, etc.) commercially available for X-ray detection is used for the X-ray detection unit 24.
An X-ray imaging optical unit 23 is disposed between the X-ray detection unit 24 and the opening of the detection unit container 21. Here, a pinhole type X-ray imaging optical unit 23a as shown in FIG. 5 or a mirror type X-ray imaging optical unit 23b as shown in FIG. 6 is used as the X-ray imaging optical unit 23.

  The structure of the pinhole type X-ray imaging optical unit 23a will be described. Referring to FIG. 5, the pinhole type X-ray imaging optical unit 23a has a shielding plate 201 that blocks X-rays. Here, a 1 mm thick metal plate made of heavy metal such as tungsten (W) or tantalum (Ta) is used as the shielding plate 201.

The shielding plate 201 is provided with a needle hole 202 that transmits X-rays and is smaller than the X-ray detection unit 24.
X-rays that are emitted from the irradiation region of the irradiation object 60 and enter the X-ray imaging optical unit 23 pass through the needle holes 202 of the shielding plate 201 due to the straightness of the X-rays, and then on the X-ray detection unit 24. An image of the irradiated area is formed.

Reference numerals 1 and 2 indicate the outer shape and diameter of the irradiation region of the irradiation object 60, respectively, and reference symbols 1 ′ and 2 ′ indicate the outer shape and diameter of the image of the irradiation region imaged on the X-ray detection unit 24, respectively. .
If the distance from the irradiation region to the shielding plate 201 is L1, and the distance from the shielding plate 201 to the X-ray detection unit 24 is L2, the ratio of the irradiation region diameter 1 to the irradiation region image diameter 1 ′ is determined by L2 / L1. Therefore, the pinhole type X-ray imaging optical unit 23a is formed by appropriately selecting L2 in accordance with the size of the X-ray detection unit 24.

  The structure of the mirror type X-ray imaging optical unit 23b will be described. Referring to FIG. 6, the mirror type X-ray imaging optical unit 23b has two concave mirrors 205 and 206 that reflect X-rays. . Here, the two concave mirrors 205 and 206 are superlattices obtained by repeatedly laminating dielectric thin films having different refractive indexes of light elements (here, Si) and heavy elements (here, W, etc.) with a thickness of nm order. It is a multilayer mirror with a structure.

  By disposing the two concave mirrors 205 and 206 so as to function as convex lenses, the mirror type X-ray imaging optical unit 23b allows the mirror center (the center of each of the two concave mirrors 205 and 206 to be centered) from the irradiation region. Assuming that the distance from the center of the connecting line segment to L1 ′ and the distance from the mirror center to the X-ray detector 24 is L2 ′, the diameter 1 of the irradiation area and the diameter of the image of the irradiation area are the same as in the pinhole type 23a The ratio of 1 ′ is determined by L2 ′ / L1 ′, and a brighter image is obtained by the area ratio of the needle hole (pinhole) 202 and the entrance of the mirror mold 23b (not shown) than the pinhole mold 23a. Can be obtained.

A window 22 is disposed on the opposite side of the X-ray detection unit 24 with the X-ray imaging optical unit 23 in the center so as to cover the opening of the detection unit container 21, and is hermetically fixed to the opening of the detection unit container 21. ing. The window portion 22 is thin so that X-rays can pass therethrough, and is formed to have a strength to keep the inside of the detection portion container 21 airtight as a vacuum wall.
Since the detector container 21 is formed of a material that blocks X-rays, when the X-rays enter the X-ray detector 20, only the X-rays that pass through the window portion 22 are the X-ray imaging optical unit 23. Has been to reach.

  The window 22 is configured so as to keep the inside of the detection unit container 21 airtight together with the detection unit container 21, and when the X-ray detection device 20 is disposed in the vacuum chamber 11 evacuated, the X-ray imaging optical unit 23. And the X-ray detector 24 is isolated from the vacuum atmosphere.

Referring to FIG. 1, the X-ray detection apparatus 20 is disposed in the vacuum chamber 11 above the irradiation material container 50 with the window portion 22 facing downward.
When the irradiation object 60 is irradiated with the electron beam, the X-ray detection device 20 emits the X-ray emitted from the irradiation region of the irradiation object 60 from the heated irradiation object 60 as described later. Vapor enters.
A filter device 70 is disposed at a position that crosses the flight path of X-rays and steam emitted from the irradiation object 60 and incident on the X-ray detection device 20.

Referring to FIG. 3, the filter device 70 includes a rotating plate 71 that shields vapor particles, a rotating shaft 73 fixed perpendicularly to the center of the rotating plate 71, and a rotating device 74 that rotates the rotating shaft 73. Have.
FIG. 4 shows a plan view of the rotating plate 71. The rotating plate 71 is provided with elongated openings 72 through which vapor particles pass so as to extend radially from the center.
Here, the length of the opening 72 in the longitudinal direction is longer than the diameter of the window 22 of the X-ray detection apparatus 20, and the rotating plate 71 is placed on the surface of the window 22 at a position where the opening 72 can face the window 22. They are arranged in parallel.

  With reference to FIG. 3, the rotation device 74 is fixed to the side surface of the detection unit container 21 of the X-ray detection device 20, and a power supply device (not shown) is electrically connected to the rotation device 74. When power is supplied from the power supply device, the rotating device 74 is configured to rotate the rotating shaft 73 around the central axis of the rotating shaft 73 together with the rotating plate 71.

  When the rotating plate 71 is rotated by the rotating device 74, X-rays and steam incident on the rotating plate 71 collide with the shielding portion when the shielding portion other than the opening 72 of the rotating plate 71 faces the window portion 22. Thus, when the opening 72 and the window 22 face each other, the window 72 passes through the opening 72 and reaches the window 22. Therefore, the filter device 70 can attenuate the amount of vapor while causing the X-ray detection device 20 to reach the X-ray and detecting the size of the irradiation region.

By reducing the length in the width direction of the opening 72 of the rotating plate 71, the amount of steam reaching the window 22 can be suppressed. At this time, the amount of X-rays incident on the window portion 22 also decreases, but the intensity of X-rays emitted from the irradiation object 60 in this embodiment is sufficiently higher than the detection performance of the X-ray detection unit 24. Since it is large, an amount of X-rays sufficient for the X-ray detection device 20 to detect the size of the irradiation region reaches the window portion 22.
An image of the irradiation region is formed on the X-ray detection unit 24 from the X-rays transmitted through the window portion 22 by the X-ray imaging optical unit 23, and the X-ray detection unit 24 determines the size of the irradiation region from the image of the irradiation region. To detect.

Referring to FIG. 1, a control device 19 is connected to the X-ray detection device 20. Here, a setting range for the size of the irradiation area is set in advance in the control device 19.
The control device 19 compares the size of the irradiation area (referred to as a detection value) detected by the X-ray detection device 20 with a preset setting range of the size of the irradiation region, and the detection value is greater than the upper limit of the setting range. When the detection value is larger, the control signal is transmitted to the electron gun power source 40 to reduce the beam diameter of the electron beam. When the detected value is smaller than the lower limit of the setting range, the control signal is transmitted to the electron gun power source 40. The beam diameter of the electron beam is enlarged to maintain the detection value within a set range.

  If the filter device 70 of the electron beam irradiation apparatus 10 according to the present invention is configured to attenuate the amount of vapor reaching the X-ray detection device 20 while allowing the X-ray detection device 20 to reach X-rays, the above-described operation can be performed. It is not limited to the configuration.

FIG. 7 shows a schematic configuration diagram of the filter device 70 a of the second example together with the X-ray detection device 20.
The filter device 70 a of the second example includes a propeller 76 that shields vapor particles, a propeller rotation shaft 77 to which the propeller 76 is fixed, and a propeller rotation device 78 that rotates the propeller rotation shaft 77.

Although FIG. 7 illustrates the case where the number of propellers 76 is four, the present invention is not limited to this, and the present invention includes cases where there are one or more propellers.
Here, the propeller rotation device 78 is fixed to the side surface of the detector container 21 of the X-ray detection device 20, and a power supply device (not shown) is electrically connected to the propeller rotation device 78. When power is supplied from the power supply device, the propeller rotating device 78 is configured to rotate the propeller rotating shaft 77 around the central axis of the propeller rotating shaft 77 together with the propeller 76.

  When the range in which the propeller 76 rotates when the propeller 76 is rotated by the propeller rotation device 78 is referred to as a rotation range, the rotation range is defined as X-rays and steam emitted from the irradiation object 60 and incident on the X-ray detection device 20. It is formed at a position that crosses the flight path.

  Here, an adhesive is applied to the plane facing the rotation direction of the propeller 76, and when the propeller 76 is rotated, the vapor particles incident on the rotation range become a plane facing the rotation direction of the rotating propeller 76. Since they collide and adhere to the plane, they cannot pass through the rotation range and do not reach the window portion 22 of the X-ray detection apparatus 20. On the other hand, X-rays incident on the rotation range do not adhere to the propeller 76 but pass through the rotation range and reach the window portion 22.

  Crossing the flight path with a time period shorter than (L / v) where v is the velocity of the vapor incident on the rotation range and L is the width of the propeller 76 in the direction along the propeller rotation axis 77. When the propeller 76 is rotated in this manner, the vapor incident on the rotation range collides with the propeller 76 and is shielded, and only X-rays can pass therethrough.

The filter device 70a of the second example is not limited to a configuration in which an adhesive is applied to a plane facing the rotation direction of the propeller 76.
Explaining another configuration of the filter device 70a of the second example, each propeller 76 has two sides, a side close to the X-ray detection device 20 and a side close to the irradiation target 60, and a side close to the X-ray detection device 20 is present. It is fixed to the propeller rotating shaft 77 in a state where it is tilted so as to advance in the rotational direction with respect to the side close to the irradiation object 60.

  When the propeller 76 is rotated, the vapor particles incident on the rotation range collide with the plane facing the rotation direction of the rotating propeller 76 and are bounced back to the irradiation object 60 side, and thus cannot pass through the rotation range. It does not reach the window portion 22 of the X-ray detection device 20. On the other hand, since the X-rays incident on the rotation range have a higher speed than the vapor particles, they pass through the rotation range and reach the window portion 22.

FIG. 8 shows a schematic diagram of the filter device 70 b of the third example together with the X-ray detection device 20.
The filter device 70b of the third example includes first and second rotating plates 81a and 81b that shield vapor particles, and first and second fixed vertically to the first and second rotating plates 81a and 81b. Rotating shafts 83a and 83b.

Here, the first and second rotating shafts 83a and 83b are connected to each other by the gear portion 85, and the rotating shaft rotating device 84 is connected to the second rotating shaft 83b.
Here, the rotating shaft rotating device 84 is fixed to the side surface of the detector container 21 of the X-ray detecting device 20, and a power supply device (not shown) is electrically connected to the rotating shaft rotating device 84.
When power is supplied from the power supply device, the rotating shaft rotating device 84 is configured to rotate the second rotating shaft 83b together with the second rotating plate 81b around the central axis of the second rotating shaft 83b. .

  When the second rotating shaft 83b is rotated, the gear portion 85 transmits power to the first rotating shaft 83a, and the first rotating shaft 83a together with the first rotating plate 81a is connected to the second rotating shaft 83b. It is configured to rotate in the same direction as the rotation direction of the second rotation shaft 83b at a rotation speed n times or 1 / n of the rotation speed (where n is a natural number of 2 or more).

  Alternatively, the gear unit 85 uses the first rotary shaft 83a together with the first rotary plate 81a at a rotational speed of m times or one-mth of the rotational speed of the second rotary shaft 83b. It may be configured to rotate in the direction opposite to the direction of rotation (where m is a natural number of 1 or more).

  The devices that rotate the first and second rotating shafts 83a and 83b together with the first and second rotating plates 81a and 81b are referred to as first and second rotating devices. The second rotating shaft 83b and the gear portion 85 constitute a first rotating device, and the rotating shaft rotating device 84 constitutes a second rotating device.

The first and second rotating plates 81a and 81b are provided with first and second openings 82a and 82b, respectively, through which vapor particles pass.
The first and second rotary plates 81a and 81b are arranged at positions that cross the flight path of X-rays and steam emitted from the irradiation object 60 and incident on the X-ray detection device 20, and are rotated by the rotary shaft rotation device 84. When the first and second rotating plates 81a and 81b are rotated, the first and second openings 82a and 82b face each other at a position crossing the flight path.

  Here, when the velocity of the vapor incident on the first rotating plate 81a is v and the interval between the first and second rotating plates 81a and 81b is d, the first and second openings 82a and 82b are The steam that passes through the first opening 82a when facing each other also passes through the second opening 82b when the rotation period of the second rotating plate 81b is a natural number times the time of (d / v). However, when the rotation period of the second rotating plate 81b is not a natural number times the time of (d / v), the second rotating plate 81b collides with a shielding part other than the second opening part 82b and is shielded.

On the other hand, the X-rays passing through the first opening 82a when the first and second openings 82a and 82b face each other have a speed higher than that of the vapor, so that the second opening 82b also passes through.
Therefore, in the filter device 70b of the third example, the second rotating plate 81b is configured to rotate at a rotation cycle that is not a natural number multiple of the time (d / v). When the portions 82a and 82b face each other at a position crossing the flight path, the steam passing through the first opening 82a collides with the shielding portion of the second rotating plate and is shielded. The X-ray passing through 82a passes through the second opening 82b and reaches the window 22 of the X-ray detection device 20.

FIG. 9 shows a schematic diagram of the filter device 70 c of the fourth example together with the X-ray detection device 20.
The filter device 70c of the fourth example includes a main roll (roll) 87 formed by winding a main film (film) 86 that shields vapor particles and transmits at least part of X-rays, and a main roll 87. A main driven shaft (driven shaft) 89 inserted at the center of the main roll 87, a main drive shaft (drive shaft) 88 around which an end of the main film 86 drawn from the outer periphery of the main roll 87 is wound, and a main drive shaft 88 And a main drive shaft rotation device (drive shaft rotation device) 80 that rotates the main drive shaft 88 around the central axis of the main drive shaft 88.

The main drive shaft 88 and the main driven shaft 89 are opposed to each other in parallel and opposite to each other across the flight path of X-rays and steam emitted from the irradiation object 60 and incident on the X-ray detection device 20. Has been placed.
When the main drive shaft 88 is rotated by the main drive shaft rotating device 80, the main film 86 is pulled, the main driven shaft 89 is rotated by the force, and the main film 86 is fed out from the main roll 87. At this time, the main driven shaft 89 generates a force opposite to the rotational force due to the pulling force applied to the main roll 87, and the main film between the main drive shaft 88 and the main driven shaft 89 is generated by the two forces. 86 is stretched on a plane.

The vapor emitted from the irradiation object 60 collides with the main film 86, adheres to the main film 86, is shielded, and at least a part of the X-rays emitted from the irradiation region of the irradiation object 60 passes through the main film 86. The light passes through and enters the X-ray detection apparatus 20.
If vapor adheres to and accumulates on the portion of the main film 86 facing the X-ray detection device 20, the X-ray transmittance of the portion decreases, leading to a decrease in detection sensitivity of the X-ray detection device 20. Since the portion is wound around the main drive shaft 88 in a roll shape, the vapor does not continue to adhere to and accumulate on the portion facing the X-ray detection device 20, and X-rays are X-rays even when the electron beam irradiation time elapses. The size of the irradiation area is detected by reaching the detection device 20.

<Electron beam irradiation method using first example of electron beam irradiation apparatus>
Next, an electron beam irradiation method using the above-described electron beam irradiation apparatus 10 will be described by taking, as an example, the case where silicon (Si) is purified by vacuum dissolution. Here, the description will be made using the filter device 70 of the first example as the filter device, but the same applies to the case of using the filter devices 70a, 70b, and 70c of the second, third, and fourth examples.

Referring to FIG. 1, the inside of the vacuum chamber 11 is evacuated. Thereafter, evacuation is continued and the vacuum atmosphere in the vacuum chamber 11 is maintained.
On the side wall of the vacuum chamber 11, a melting material adding device 12 is inserted in an airtight manner. The melting material adding device 12 can carry the irradiation object 60 from the outside to the inside of the vacuum chamber 11 while maintaining the vacuum atmosphere in the vacuum chamber 11, and can place the irradiation object 60 on the irradiation material container 50. It is configured.

The melting material adding device 12 is operated, and while the vacuum atmosphere in the vacuum chamber 11 is maintained, silicon as the irradiation object 60 is carried into the vacuum chamber 11 and placed on the irradiation material container 50.
The rotating plate 71 of the filter device 70 is rotated between the irradiation object 60 and the window 22.
A setting range of the size of the irradiation area is set in advance in the control device 19. Here, the setting range is a value determined by simulation or experiment.

Referring to FIG. 2, when the inside of the vacuum chamber 11 is evacuated, the inside of the housing 31 of the electron gun 30 is also evacuated.
When the pressure in the vacuum chamber 11 enters the 10 ⁻² Pa range, the inside of the gun chamber 110 and the intermediate chamber 112 of the electron gun 30 is evacuated by an exhaust system (not shown), and the partition valve 39 is opened.

Since the intermediate chamber 112 is provided and the working exhaust structure is provided, the pressure in the vacuum chamber 11 is increased by electron beam irradiation and the like, and the pressure in the gun chamber 110 is reduced to about 1 × 10 ⁻¹ Pa. It can be kept at ^10-3 Pa or less. Thereby, abnormal discharge in the gun chamber 110 can be prevented, and burning of the filament 32 and the cathode 33 can be prevented.
The casing 31, the anode 35, the vacuum chamber 11, and the irradiation material container 50 of the electron gun 30 are all electrically grounded.

  A voltage is applied between the filament 32 and the cathode 33 so that the potential of the cathode 33 becomes positive with respect to the potential of the filament 32. Further, a voltage is applied between the cathode 33 and the anode 35 so that the potential of the cathode 33 is negative (in this case, −40 kV) with respect to the ground potential (0 V) of the anode 35. Further, a current is supplied to the first and second lenses 36 and 37 to form magnetic fields in the connection path 111 and the discharge path 113, respectively, and a current is supplied to the swing coil 38 to form a magnetic field in the muzzle 114. Keep it.

When the intermediate chamber 112 enters the 10 ⁻³ Pa level and the gun chamber 110 enters the 10 ⁻⁴ Pa level, current is supplied from the filament power supply 41 to the filament 32 to heat the filament 32. When the filament 32 reaches a high temperature (here, 2800 K), thermoelectrons are generated from the filament 32.

The thermoelectrons are accelerated toward the cathode 33, collide with the cathode 33, and heat the cathode 33.
Thermoelectrons are generated from the heated cathode 33. The amount of generated thermoelectrons increases as the temperature of the cathode 33 increases. The temperature of the cathode 33 is controlled by the cathode heating power source 42, and accordingly, the amount of thermoelectrons generated is controlled by the cathode heating power source 42.

The Wehnelt 34 has the same potential as that of the cathode 33 and serves to suppress the divergence of electrons from the cathode 33 and lead it to the anode 35.
Electrons that have passed through the inside of the cylindrical shape of the anode 35 are converged by the magnetic field of the first lens 36, pass through the opening of the partition valve 39, pass through the intermediate chamber 112, and then converged again by the magnetic field of the second lens 37. The Further, the electrons are subjected to trajectory correction by the magnetic field of the oscillating coil 38 and are emitted into the vacuum chamber 11.

The electrons generated from the cathode 33 in this manner are linearly shaped and transported inside the casing 31 of the electron gun 30 and are therefore usually called electron beams.
As described above, the casing 31, the anode 35, the vacuum chamber 11, and the irradiation material container 50 of the electron gun 30 are all electrically grounded, and the irradiation object 60 is also electrically grounded via the irradiation material container 50. Has been.

  The electron beam is first accelerated by the difference (40 kV) between the potential of the cathode 33 (here, 40 kV) and the ground potential (0 V) of the anode 35, and acquires 40 keV energy. After that, it passes through the ground potential space (that is, the electric field free space), and is irradiated to the irradiation object 60 at the ground potential with the energy of 40 keV, and the irradiation object 60 is heated (see FIG. 1).

While irradiating the electron beam, the magnetic field of the oscillating coil 38 is controlled so that the electron beam trajectory is oscillated so that the irradiation region of the electron beam moves inside the surface (irradiation surface) of the irradiation object 60. Also good. In this case, since the irradiation surface of the irradiation object 60 is heated uniformly, it can prevent that an unevenness | corrugation arises in an irradiation surface by local heating.
In the present embodiment, the power of the electron beam is determined by the current of the electron beam. When the current is 1 A, 40 kV × 1 A = 40 kW.

X-rays are emitted from the irradiation region of the irradiation object 60 irradiated with the electron beam.
X-rays emitted from the irradiation region enter the filter device 70. When the opening 72 of the filter device 70 faces the window 22 of the X-ray detection device 20, the X-ray that has passed through the opening 72 of the filter device 70 passes through the window 22 of the X-ray detection device 20. The X-ray imaging optical unit 23 forms an image on the X-ray detection unit 24, and the X-ray detection unit 24 detects the size of the irradiation region.

The control device 19 monitors the detection value of the X-ray detection device 20.
When, for example, the pressure in the vacuum chamber 11 is increased during irradiation with an electron beam, the action of converging the beam diameter of the electron beam works due to ions produced by the electrons themselves, and the size of the emission region is reduced.

  At this time, the control device 19 sends a control signal to the electron gun power source 40 based on the size of the irradiation area detected by the X-ray detection device 20 to control the magnetic field generated by the first and second lenses 36 and 37. Thus, the beam diameter of the electron beam emitted from the electron gun 30 is enlarged.

  Even when the size of the emission region is enlarged during irradiation with the electron beam, the control device 19 sends a control signal to the electron gun power supply 40 based on the size of the irradiation region detected by the X-ray detection device 20. The magnetic field generated by the first and second lenses 36 and 37 is controlled to reduce the beam diameter of the electron beam emitted from the electron gun 30.

By controlling the beam diameter of the electron beam in this way, the size of the irradiation region can be controlled within the set range, and the power density of the irradiation region can be kept constant.
By accurately controlling the power density in the irradiated area, it is possible to prevent the dissolved silicon from bumping and scattering, preventing unnecessary loss of dissolved silicon, and producing high-purity crystalline silicon for solar cells. become.

  In order to keep the power density constant when the size of the irradiation region changes and the power density of the irradiation region changes, the magnetic field generated by the first and second lenses 36 and 37 is controlled as described above. In addition to the method of changing the beam diameter of the electron beam (magnetic field control method), a method of controlling the temperature of the cathode 33 and changing the amount of current of the electron beam (temperature control method) is also conceivable. However, the magnetic field control method is preferable because the power density of the irradiation region can be controlled in a shorter time than the temperature control method.

The irradiation object 60 irradiated with the electron beam and heated is dissolved, and the impurities contained in the irradiation object 60 are evaporated.
If the vapor adheres to and accumulates on the window portion 22 of the X-ray detection device 20, the amount of X-ray transmission through the window portion 22 decreases, leading to a decrease in detection sensitivity of the X-ray detection device 20. Since the rotating plate 71 of the filter device 70 is rotated between the window portion 22 and the shielding portion other than the opening portion 72 of the window portion 22 and the rotating plate 71 face each other, the vapor is shielded by the shielding portion and the window portion. When the window portion 22 and the opening portion 72 face each other, the vapor that has passed through the opening portion 72 reaches the window portion 22, and the vapor is prevented from being deposited on the window portion 22. Has been.

Since the inside of the vacuum chamber 11 is evacuated, the impurity vapor is evacuated from the inside of the vacuum chamber 11 and the silicon that is the irradiation object 60 is subjected to vacuum melting and purification.
A tilting mechanism (not shown) is connected to the irradiation material container 50. The tilting device is configured to tilt the irradiation material container 50 up to 90 degrees from the horizontal position.
After completion of dissolution and purification, the tilting mechanism is operated, and the melted irradiation object 60 is emptied in a mold container (not shown) installed in the vacuum chamber 11.

  Next, the irradiation material container 50 is returned to the horizontal position by operating the tilting mechanism, the dissolving material adding device 12 is operated, the irradiation object 60 is placed on the irradiation material container 50, and the electron beam is again emitted from the electron gun 30. The irradiation object 60 is irradiated and dissolution purification is performed.

  This cycle is repeated, and when the mold container is full, the vacuum chamber 11 is released to the atmosphere, and after purifying silicon from the mold, the mold is returned to the original position in the vacuum chamber 11, The evacuation is resumed and the next dissolution purification cycle is entered.

  In the above description, the present invention has been described by taking the vacuum dissolution purification of silicon as an example. It can also be used for vacuum melting and purification of active metals such as titanium, vacuum materials such as stainless steel, and refractory metals such as molybdenum and tantalum.

  By detecting the size of the irradiation region with an X-ray detection device, the power density of the irradiation region during electron beam irradiation can be accurately controlled, so that a high-quality metal, such as high-purity titanium (Ti), Production of tantalum (Ta) or the like becomes possible.

The present invention can also be used for vacuum deposition of aluminum, titanium, copper and the like.
In the case of vacuum deposition, the film formation rate can be kept constant by keeping the power density of the irradiated region constant, so that the quality of the thin film product can be improved.

  The power of the electron beam is adjusted according to the type of irradiation object. In order to dissolve tantalum and tungsten, which are refractory metals compared to silicon, titanium, and stainless steel, greater power is required, but the power density in the irradiated area can be controlled with higher accuracy than before, so the above It is possible to melt refractory metals such as the above, and the application field of high-power electron guns can be expanded.

<Structure of second example of electron beam irradiation apparatus>
The structure of the second example of the electron beam irradiation apparatus according to the present invention will be described. This electron beam irradiation apparatus is a take-up vacuum deposition apparatus.
FIG. 10 shows an internal configuration diagram of the electron beam irradiation apparatus 10 ′ of the second example. The structure of the electron beam irradiation apparatus 10 ′ of the second example is the same as the structure of the electron beam irradiation apparatus 10 of the first example except for the part related to the film module 90 described later, and the electron beam irradiation apparatus 10 of the first example. The same parts as those in FIG.

A film module 90 is disposed above the irradiation material container 50.
The film module 90 has a sub drive shaft 92, a sub driven shaft 93, and a sub roll 94.
The sub drive shaft 92 and the sub driven shaft 93 are disposed above the irradiation material container 50 so as to face each other in parallel.

The sub roll 94 is formed by winding a sub film 91 that is a deposition target. The sub film 91 is made of a material that transmits at least part of incident X-rays.
A sub driven shaft 93 is inserted in the center of the sub roll 94. The end portion of the sub film 91 is drawn out from the outer periphery of the sub roll 94, and the end portion of the sub film 91 drawn out is wound around the sub drive shaft 92.

A sub drive shaft rotating device 95 is connected to the sub drive shaft 92, and the sub drive shaft rotating device 95 is configured to be able to rotate the sub drive shaft 92 around the central axis of the sub drive shaft 92.
When the sub drive shaft 92 is rotated around the central axis by the sub drive shaft rotating device 95, the sub film 91 is pulled, and the sub driven shaft 93 is rotated by the force to feed the sub film 91 from the sub roll 94.

  At this time, a force opposite to the rotational force due to the pulling force applied to the sub roll 94 is generated in the sub driven shaft 93, and the force between the sub drive shaft 92 and the sub driven shaft 93 is generated by the two forces. The sub film 91 is stretched flat.

Here, a film of PET, PP, polyimide or the like having a width of 600 to 1200 mm, a thickness of 2 to 3 μm, and a roll length of about 1600 m is used for the sub film 91.
The sub drive shaft rotating device 95 is configured to rotate the sub drive shaft 92 so that the sub film 91 is fed out at a speed of about 350 m / min.

The X-ray detector 20 is disposed on the opposite side of the irradiation material container 50 with the sub film 91 in the center.
Between the sub film 91 and the irradiation material container 50, a deposition preventing plate 96 that shields the vapor is disposed so as to cover the lower side of the sub film 91. An opening through which X-rays and steam pass is provided at a position facing the irradiation material container 50 in the deposition preventing plate 96.

<Electron beam irradiation method using second example of electron beam irradiation apparatus>
The electron beam irradiation method using the electron beam irradiation apparatus 10 ′ of the second example will be described by taking as an example the case where aluminum (Al) is wound up and deposited on the sub film 91.
Similarly to the first example, aluminum as the irradiation object 60 is carried into the evacuated vacuum chamber 11 by the melting material adding device 12 and placed on the irradiation material container 50.

Here, the irradiation material container 50 is a water-cooled hearth, and a temperature-controlled liquid is circulated in a flow path (not shown) provided in the irradiation material container 50. Thereafter, the temperature-controlled liquid circulation is continued.
The irradiation target 60 is heated by irradiating an electron beam from the electron gun 30. The heated irradiation object 60 dissolves and evaporates.

The sub drive shaft 92 is rotated by the sub drive shaft rotating device 95 to move the sub film 91 on the irradiation object 60.
The vapor released from the irradiation object 60 and passing through the opening of the deposition preventing plate 96 reaches the sub-film 91 and adheres thereto.
Since the sub drive shaft 92 is rotated, the portion of the sub film 91 where the vapor is deposited is wound around the sub drive shaft 92 in a roll shape.

X-rays are emitted together with vapor from the irradiation region of the irradiation object 60 irradiated with the electron beam.
X-rays emitted from the irradiation area pass through the sub-film 91 and enter the X-ray detection device 20, and the size of the irradiation area is detected.
The control device 19 monitors the detection value of the X-ray detection device 20.

When, for example, the pressure in the vacuum chamber 11 is increased during irradiation with an electron beam, the action of converging the beam diameter of the electron beam works due to ions produced by the electrons themselves, and the size of the emission region is reduced.
At this time, the control device 19 sends a control signal to the electron gun power source 40 based on the size of the irradiation area detected by the X-ray detection device 20 to control the magnetic field generated by the first and second lenses 36 and 37. Thus, the beam diameter of the electron beam emitted from the electron gun 30 is enlarged.

Even when the size of the emission region is enlarged during irradiation with the electron beam, the control device 19 sends a control signal to the electron gun power supply 40 based on the size of the irradiation region detected by the X-ray detection device 20. The magnetic field generated by the first and second lenses 36 and 37 is controlled to reduce the beam diameter of the electron beam emitted from the electron gun 30.
By controlling the beam diameter of the electron beam in this way, the size of the irradiation region can be maintained within the set range, and the power density of the irradiation region can be kept constant.

Since the deposition rate is kept constant by keeping the power density in the irradiation region constant, an aluminum film is continuously formed on the sub-film 91 at a constant film thickness of, for example, several hundred nm (film resistance is 1.6Ω). Can be vapor deposited.
When the vapor deposition of one roll is completed, the vacuum chamber 11 is released to the atmosphere, the roll-shaped subfilm 91 is taken out, and then the subroll 94 made of the non-deposited subfilm 91 is loaded into the film module 90. The vacuum evacuation was resumed and the next winding vapor deposition cycle was started.

  In the electron beam irradiation apparatus 10 ′ of the second example, the vapor released from the irradiation object 60 adheres to the sub film 91 that is the film formation object, and does not enter the X-ray detection apparatus 20. Unlike the electron beam irradiation device 10, the filter device 70 can be omitted.

DESCRIPTION OF SYMBOLS 10, 10 '... Electron beam irradiation apparatus 11 ... Vacuum chamber 13 ... Vacuum exhaust apparatus 19 ... Control apparatus 23, 23a, 23b ... X-ray imaging optical part 24 ... X-ray detection part 60 ... Irradiation Object 70, 70a, 70b, 70c …… Filter device 76 …… Propeller 77 …… Propeller rotating shaft 78 …… Propeller rotating device 81a, 81b …… First and second rotating plates 82a, 82b …… First, Second opening 83a, 83b ...... first and second rotating shafts 86 ... film (main film)
87 …… Roll (main roll)
88 …… Drive shaft (main drive shaft)
89 …… Driven shaft (Main driven shaft)
201 …… Shielding plate 202 …… Needle hole 205, 206 …… Concave mirror

Claims (4)

A vacuum chamber;
An evacuation device for evacuating the vacuum chamber;
An electron gun configured to emit an electron beam into the vacuum chamber;
Have
An electron beam irradiation apparatus configured to irradiate an irradiation object placed in the vacuum chamber with an electron beam from the electron gun to heat the irradiation object,
When an area that is irradiated with the electron beam on the surface of the irradiation object and emits X-rays is an irradiation area,
An X-ray detector that is disposed at a position where X-rays emitted from the irradiation region are incident, and detects the size of the irradiation region from the incident X-rays;
An X-ray imaging optical unit that forms an image of the irradiation region on the X-ray detection unit from the X-rays emitted from the irradiation region;
I have a,
Between the irradiation object and the X-ray imaging optical unit, the X-ray is emitted from the heated irradiation object while the X-ray reaches the X-ray imaging optical unit, and the X-ray imaging is performed. An electron beam irradiation device in which a filter device that attenuates the amount of vapor reaching the optical unit is disposed,
The filter device includes first and second rotating plates that shield the vapor particles, first and second rotating shafts fixed perpendicularly to the first and second rotating plates, and the first The first and second rotating devices for rotating the second rotating shaft together with the first and second rotating plates around the central axis of the first and second rotating shafts,
The first and second rotating plates are respectively provided with first and second openings for allowing the vapor particles to pass therethrough,
When the first and second rotating plates are rotated at different speeds by the first and second rotating devices, the first and second openings have a flight path between the X-ray and the steam. To face each other in a crossing position,
When the first and second openings face each other at a position crossing the flight path of the X-rays and the steam, the steam passing through the first opening becomes the second rotating plate. An electron beam irradiation apparatus configured to collide with and shield the shielding part other than the second opening .   The electron beam irradiation apparatus according to claim 1, further comprising a control device that controls a beam diameter of the electron beam based on a size of the irradiation region detected by the X-ray detection unit. The X-ray imaging optical unit has a shielding plate that shields the X-ray,
The shield plate has a needle hole smaller than the X-ray detector that allows the X-ray to pass through,
The electron beam irradiation apparatus according to claim 1 , configured to form an image of the irradiation region on the X-ray detection unit from the X-rays that have passed through the needle hole. The X-ray imaging optical unit has a concave mirror that reflects the X-ray,
The electron beam irradiation apparatus according to claim 1 , configured to form an image of the irradiation region on the X-ray detection unit from the X-ray reflected by the concave mirror.

Images