JP7197927B2 - Electron beam generator and attachment member - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electron beam generator and an attachment member, and more particularly to technology for improving the quality of electron beams for vapor deposition.

A vacuum vapor deposition apparatus based on the electron beam vapor deposition method has an electron beam generator (see, for example, Patent Document 1). In such a vacuum vapor deposition apparatus, an electron beam generated by an electron beam generator is irradiated onto a vapor deposition material in a crucible while being bent by the action of a magnetic field or the like. This evaporates the vapor deposition material and forms a vapor deposition film on the surface of the object. Electron beam generators are also called electron guns or electron beam guns.

The electron beam generator has a filament that emits thermal electrons. A filament generally has a filament body and two filament legs. Various forms of filament bodies are known. All or most of each filament leg usually has a simple form, in particular a straight form.

Patent Document 2 discloses an electron beam generator for vapor deposition. In the electron beam generator, a linear member is wound around the intermediate portion of each filament leg. Patent Document 2 does not disclose a member that wraps each filament leg in a non-contact manner.

Note that Patent Document 3 discloses an ion source for plasma generation. The ion source is used in ion implantation and not in vapor deposition. The ion source has a filament positioned within the plasma-generating vessel. The filament has a U-shape as a whole, and is specifically composed of an arcuate intermediate portion and two linear portions extending from both ends of the intermediate portion. The vicinity of the base of each linear portion (specifically, the portion where the raw material gas is liquefied when the raw material gas adheres) is wrapped with a sheath. The length of each sheath is rather small compared to the length of each linear segment. In order to increase the amount of arc discharge in the plasma generating vessel, it is better to increase the exposed portion of the filament, so as long as the function of each sheath can be secured, the length of each sheath should be reduced. understood to be good.

JP-A-2004-192903 Japanese Patent Application Laid-Open No. 2003-297273 Japanese Patent Application Laid-Open No. 2003-317640

SUMMARY OF THE INVENTION An object of the present invention is to improve the quality of an electron beam in an electron beam generator for vapor deposition. Another object of the present invention is to increase the temperature of the filament body or to homogenize the temperature distribution of the filament body in an electron beam generator for vapor deposition. Another object of the present invention is to suppress thermionic emission from sources other than the filament body. Alternatively, it is an object of the present invention to extend filament life.

An electron beam generator according to the present invention comprises a filament body, a filament having a first filament leg connected to one end of the filament body, and a second filament leg connected to the other end of the filament body, and the first filament leg. a first holding portion that holds a first held portion; a second holding portion that holds a second held portion portion of the second filament leg; A first enclosing portion that encloses a first enclosing portion that exists on the filament main body side in a non-contact manner, and a second enclosing portion that exists closer to the filament main body than the second held portion in the second filament leg. a second enclosing portion that encloses the filament body in a non-contact manner, wherein the first exposed portion is between the first held portion and one end of the filament body in the first filament leg, and the second filament leg includes the A second exposed portion is between the second held portion and the other end of the filament body, and the ratio of the length of the first surrounded portion to the length of the first exposed portion is 60% or more, A ratio of the length of the second surrounded portion to the length of the second exposed portion is 60% or more.

An attachment member according to the present invention includes an enclosing portion that encloses a filament leg of a filament that generates an electron beam in a non-contact manner, the enclosing portion having a hollow shape extending in the axial center direction of the filament leg, and The leg is composed of a held portion and an exposed portion connected thereto, and the surrounding portion surrounds the surrounded portion continuing to the held portion in the exposed portion, and the length of the exposed portion is surrounded by the surrounding portion. It is characterized in that the proportion of the length of the portion is 60% or more.

ADVANTAGE OF THE INVENTION According to this invention, it is an electron beam generator for vapor deposition. WHEREIN: The quality of an electron beam can be improved. Alternatively, according to the present invention, the temperature of the filament body can be increased or the temperature distribution of the filament body can be made uniform in the electron beam generator for vapor deposition. Alternatively, according to the present invention, it is possible to suppress thermionic emission from sources other than the filament body. Alternatively, according to the present invention, filament life can be extended.

1 is a side view showing an electron beam generator according to a first embodiment; FIG. 1 is a perspective view showing a first example of a filament assembly; FIG. 1 is a cross-sectional view showing a first example of a filament assembly; FIG. FIG. 10 is a side view showing one filament leg and sheath; FIG. 11 is a side view showing the other filament leg and sheath; FIG. 4 is a cross-sectional view showing a second example of a filament assembly; FIG. 10 is a cross-sectional view showing a third example of a filament assembly; FIG. 11 is a cross-sectional view showing a fourth example of a filament assembly; FIG. 11 is a cross-sectional view showing a fifth example of a filament assembly; It is a figure which shows the 1st modification of a filament. It is a figure which shows the modification of an attachment member. It is a figure which shows the modification of a structure. FIG. 10 is a diagram showing a second modified example of the filament; It is a side view which shows the electron beam generator which concerns on 2nd Embodiment. FIG. 4 is a cross-sectional view showing a filament assembly according to a comparative example; It is a figure which shows a vapor deposition apparatus.

Hereinafter, embodiments will be described based on the drawings.

(1) Outline of Embodiment An electron beam generator for vapor deposition according to an embodiment includes a filament, a first holding section, a second holding section, a first enclosing section, and a second enclosing section. The filament has a filament body, a first filament leg connected to one end of the filament body, and a second filament leg connected to the other end of the filament body. The first holding portion is a member that holds the first held portion of the first filament leg. The second holding portion is a member that holds the second held portion of the second filament leg. The first enveloping part is a member that encloses, without contact, the first enveloping portion that exists closer to the filament main body than the first held portion in the first filament leg. The second enveloping part is a member that encloses the second enveloping portion, which is located closer to the filament main body than the second held portion in the second filament leg, in a non-contact manner. A first exposed portion is between the first held portion and one end of the filament body in the first filament leg. A second exposed portion is between the second held portion and the other end of the filament body in the second filament leg. The ratio of the length of the first surrounded portion to the length of the first exposed portion is 60% or more. The ratio of the length of the second surrounded portion to the length of the second exposed portion is 60% or more.

Hereinafter, as the case may be, both the first filament leg and the second filament leg are referred to as filament legs, the first retained portion and the second retained portion are both referred to as retained portions, and the first wrapped portion and the second Both of the enclosed portions are referred to as enclosed portions, and both the first exposed portion and the second exposed portion are referred to as exposed portions. Also, both the first holding portion and the second holding portion are referred to as holding portions, and the first enclosing portion and the second enclosing portion are both referred to as enclosing portions.

According to the above configuration, most of the exposed portion (more specifically, 60% or more) of the filament leg is surrounded by the surrounding portion, so that all or part of the advantages described below can be obtained.

Radiant energy emitted from the enclosed portion of the filament leg reaches the envelope, where the radiant energy is absorbed. In the configuration example described below, heat conduction also occurs from the filament legs to the enclosure. Radiation (and heat conduction) raises the temperature of the enclosure. Since the surrounding portion of the filament leg is wrapped by the surrounding portion as the high-temperature body without contact, temperature drop in the filament leg is suppressed, and heat outflow via the filament leg is suppressed. That is, the temperature of the filament legs is raised. As a result, the temperature of the filament body rises, or the temperature distribution in the filament body becomes uniform. In particular, it is possible to effectively suppress the temperature drop near the one end and the other end of the filament body. As a result, the amount of thermal electrons emitted from the filament body can be increased. That is, the quality of the electron beam can be improved (first advantage).

For example, if the two filament legs are perpendicular to the thermoelectron extraction direction and the two enclosures are not provided, the thermoelectrons emitted from the two filament legs spread the electron beam. Fear arises. On the other hand, if the above configuration is adopted, the thermoelectrons emitted from the enclosed portion can be intercepted by the enclosing portion, so deterioration of the quality of the electron beam can be prevented or suppressed (second advantage).

According to experiments by the present inventors, it has been confirmed that when the filament is used in an oxygen atmosphere, the adoption of the above configuration can extend the life of the filament. More specifically, if the enclosing part is not used, the intermediate portion of the filament leg is oxidized, the diameter of the intermediate portion is reduced, and the filament is finally broken. On the other hand, by wrapping the filament legs in a non-contact manner with the surrounding portion, oxidation can be suppressed (third advantage). The reason for this may be that the temperature of the entire filament leg has risen, making it difficult to generate an intermediate temperature that is likely to cause oxidation in the filament leg, or that the surrounding portion itself has made it difficult for oxygen molecules to reach the filament leg. In addition, it can be pointed out that oxygen molecules may have difficulty reaching the filament legs due to the oxidized particles released into the surrounding portion. It is also possible to point out the possibility that multiple oxidation suppression mechanisms are working at the same time.

The length of the exposed portion is the length along the virtual central axis of the filament legs. Similarly, the length of the enclosed portion is the length along the virtual central axis of the filament legs. length. The length of the enclosed portion is also the length of the enclosure. Each length is the length along the material axis. The material axis is an axis passing through the center of gravity on the cross section (cross section) at each position along the longitudinal direction of the member.

If the surrounded portion is not dominant in the exposed portion, specifically, if the ratio of the length of the surrounded portion to the length of the exposed portion is less than 60%, the filament due to heat outflow from both ends of the filament body It is not possible to sufficiently suppress the temperature drop of the main body, or temperature variations occur in the filament main body. Therefore, in order to improve the quality of the electron beam, it is required that most or most of the exposed portion be the enclosed portion. Specifically, the ratio of the length of the enclosed portion to the length of the exposed portion is required to be 60% or more. In order to improve the quality of the electron beam, the ratio should be 80% or more, preferably 85% or more. The entire exposed portion may be surrounded by the surrounding portion, ie the above percentage may be 100%. In order to reliably avoid contact between the filament body and the enclosing part, the above ratio may be 98% or less or 96% or less.

In order for the enclosing part to function satisfactorily, it is better to bring the inner surface of the enclosing part closer to the outer surface of the part to be enclosed. That is, it is better to make the gap between them small. However, the size of the gap is determined so as to reliably avoid contact between the portion to be surrounded and the surrounding portion.

Heat conduction occurs from the held portion of the filament leg to the holding portion. As long as the filament can be stably and reliably held, if the held portion is made small, the amount of heat flowing out from the held portion to the holding portion can be reduced, and the temperature drop of the filament legs as a whole can be further suppressed. . The ratio of the length of the held portion to the length of the entire filament leg may be, for example, 20% or less or 30% or less. In that case, the ratio may be 5% or more or 10% or more. Each length is the length along the central axis, as already explained.

In an embodiment, the first enclosing part has a tubular shape that absorbs heat radiated from the first enclosing part and blocks thermal electrons emitted from the first enclosing part. The second enclosing part has a cylindrical shape that absorbs heat radiated from the second enclosing part and blocks thermoelectrons emitted from the second enclosing part. According to this configuration, it becomes easier to uniformly raise the temperature of each of the surrounding portions. Also, the manufacturing and installation of each enclosing part is facilitated.

The electron beam generator according to the embodiment further includes a first clamping mechanism that clamps the first enclosure and a second clamping mechanism that clamps the second enclosure. If the outer surface of each surrounding portion is a cylindrical surface, there is no need to consider the orientation of each surrounding portion when installing the surrounding portions. The two clamping mechanisms can stably and reliably clamp the two enclosures. Two clamping mechanisms may clamp the two retaining parts in addition to the two enclosing parts. Each clamping mechanism is a structure that acts as a fixing means or holding means.

In the embodiment, the first holding portion and the first enclosing portion are integrated, and the second holding portion and the second enclosing portion are integrated. That is, the first holding portion and the first enclosing portion are configured by a single member, and the second holding portion and the second enclosing portion are configured by another single member. This configuration facilitates the installation work of the first holding portion and the first enclosing portion, and the installation work of the second holding portion and the second enclosing portion. Also, heat conduction from each holding portion to each surrounding portion can be improved.

In the embodiment, the first attachment member is configured by the first holding portion and the first enclosing portion, and the second attachment member is configured by the second holding portion and the second enclosing portion. The first attachment member and the second attachment member have the same shape. If the attachment method is adopted, that is, if the filament and the holding portion/surrounding portion are separated, it becomes possible to attach an attachment member to the filament as required. If the first attachment member and the second attachment member have the same shape, there is no need to consider the type of attachment member when installing the attachment member. Also, when the attachment member is worn out, it becomes easy to replace it.

It is also conceivable to provide the holding part and the enclosing part fixedly for each filament leg. For example, the filament may be constructed by integrating or assembling the first retaining portion, the second retaining portion, the first enclosing portion, and the second enclosing portion.

In an embodiment, the first retaining part and the first enclosing part are a first structure with a first cavity through which the first enclosed part passes. The first structure absorbs heat emitted from the first enclosed portion and blocks thermal electrons emitted from the first enclosed portion. The second holding part and the second enclosing part are a second structure having a second cavity through which the second enclosed part passes. The second structure absorbs heat emitted from the second enclosed portion and blocks thermoelectrons emitted from the second enclosed portion. Each of the first structure and the second structure may be composed of one or more blocks. The first cavity and the second cavity are respectively wells through which the enclosed part is passed contactlessly. The bottom wall of the well corresponds to the holding part.

In an embodiment, the first filament leg has a first straight portion including the first wrapped portion, and an inclined portion connecting to the first straight portion via the bend. The second filament leg has a second straight portion that includes a second wrapped portion. The first enveloping portion extends to or near the bent portion. The length of the first enclosing portion and the length of the second enclosing portion are the same. This configuration makes it easier to avoid contact between the first filament leg (especially the inclined portion thereof) and the first enveloping portion. In addition, the shape of the first enclosing portion and the shape of the second enclosing portion can be matched. The angled portion is the interface between the first straight portion and the filament body.

An attachment member according to an embodiment includes an enclosure for contactlessly enclosing filament legs of a filament that produces an electron beam. The enveloping part has a hollow shape extending in the central axis direction of the filament legs. A filament leg is composed of a held portion and an exposed portion connected thereto. An exposed portion is a portion that is not in contact with other members. The surrounding portion surrounds the surrounding portion that continues to the held portion in the exposed portion. The ratio of the length of the enclosed portion to the length of the exposed portion is 60% or more. The attachment member is typically configured as a replaceable consumable item, but may be configured as a structure (that is, non-consumable item) that is incorporated into the electron beam generator.

An attachment member according to embodiments includes a bottom integral with the enclosure. The bottom part has a holding hole into which the part to be held is inserted. This configuration facilitates installation of the filament. Integrating the enclosing part and the holding part facilitates their manufacture and handling.

In any type of vapor deposition filament, the filament body has a central axis parallel to the direction (first direction) perpendicular to the beam extraction direction, in other words, the filament body has one end spaced apart in the first direction. and the other end. In a filament having two filament legs extending in a second direction orthogonal to the first direction from both ends of the filament body, the filament body may have a complex shape such as a helical shape, a straight shape, or a curved shape. form, etc. In that case, the filament body has a constant width in the second direction, and the two portions beyond that width are defined as the two filament legs. In filaments in which two filament bodies extend parallel to the first direction from both ends of the filament body, the filament bodies have a non-linear form such as a helical form, a plate-like form, or the like. In that case, the two portions beyond the ends of the portion with non-linear morphology may be defined as two filament legs. When two portions having an L-shape are drawn from opposite ends of a portion having a non-linear configuration, the non-linear portion is defined to be the filament body, and the two portions drawn therefrom are defined as the filament body. Defined to be two filament legs.

(2) Details of Embodiment FIG. 1 shows an electron beam generator 10 for vapor deposition according to a first embodiment. The electron beam generator 10 is arranged in a vacuum chamber in a vacuum deposition apparatus. An electron beam generated by the electron beam generator 10 is irradiated onto the vapor deposition material in the crucible. When forming a metal oxide film such as a silicon dioxide (SiO ₂ ) film, a zirconium oxide (ZrO ₂ ) film, a titanium oxide (TiO ₂ ) film, etc. as a vapor deposition film on the surface of the object, oxygen gas is is introduced. However, the configuration described below can function effectively even when oxygen gas is not introduced into the vacuum chamber.

Although FIG. 1 also shows an electrical circuit, it is supplemental and illustrative. In the following description, for example, the x-direction is the first horizontal direction, the y-direction is the second horizontal direction, and the z-direction is the vertical direction.

The component 12 is made of, for example, a conductive material such as copper, and an anode electrode 30 as a lead electrode is fixed to the component 12 . A base 16 is connected to the component 12 via an insulating member 14 . The insulating member 14 is, for example, an insulator. The base 16 is made of stainless steel, for example.

The pedestal pair 18 is composed of a pair of pedestals, which are fixed to the base 16, as will be described later. A pair of pedestals are physically and electrically separated from each other. The base 16 may be composed of a pair of base members.

Four blocks 22R, 24R, 22L and 24L are mounted on the pedestal pair 18. As shown in FIG. They contain two block pairs aligned in the x-direction. Each block pair is composed of two blocks arranged in the y direction. Each block 22R, 24R, 22L, 24L is made of a conductive material such as stainless steel or copper.

The filament 26 is made of tungsten, for example. The filament 26 is a member that emits thermal electrons due to heat generation. The filament 26 is composed of a filament body and two filament legs (a first filament leg and a second filament leg), as will be described later. When a filament current is passed through the filament 26 , the filament 26 heats up to a very high temperature, and thermal electrons are emitted from the filament 26 . When filament 26 is exhausted, it is replaced with a new one.

In the embodiment, two filament legs of filament 26 are surrounded by two sheaths 40,42. The individual sheaths 40 and 42 are made of, for example, heat-resistant metal or ceramic, and are made of stainless steel in the embodiment. Each sheath 40, 42 surrounds each filament leg to limit heat flow out of the filament body, thereby raising the temperature of the filament body or equalizing the temperature distribution of the filament body. In addition to the above basic benefits, each sheath 40, 42 also provides a number of secondary benefits, which will be described below, depending on the filament 26 installation and use environment. The construction and operation of each sheath 40, 42 will be detailed later.

A filament assembly 300 according to the first example includes a filament 26, a pair of sheaths 40, 42, a base pair 18, and a plurality of blocks 22R, 24R, 22L, 24L. The two blocks 22R, 24R on the right side and the two blocks 22L, 24L on the left side respectively function as clamping mechanisms. Two clamping mechanisms clamp the two sheaths 40 , 42 to hold the filament 26 . A beam shaping electrode 32 is provided so as to cover the filament body of the filament 26 .

A constant voltage is applied between the two filament legs by power supply 36 to cause filament current to flow through filament 26 . As a result, the filament 26 generates heat and thermal electrons are emitted from the filament 26 . On the other hand, the anode electrode 30 is grounded. A power supply 34 applies a negative voltage in the range of -4 to -12 kV, for example, to the filament 26 . This negative voltage works as an extraction voltage for accelerating thermoelectrons emitted from the filament 26 in a predetermined direction. An electron beam 38 is thereby generated.

The beam extraction direction is the -y direction. In the first embodiment, each filament leg is orthogonal to the beam extraction direction. In a second embodiment shown later in FIG. 14, each filament leg is parallel to the beam extraction direction.

A beam shaping electrode 32 is provided to manipulate the electric field near the filament 26 to produce a good electron beam 38 . The arrangement and configuration of the filament 26, anode electrode 30, beam shaping electrode 32, etc. are examples. The electron beam 38 is deflected by a magnetic field formed by a permanent magnet or an electromagnet (not shown), and irradiated onto the vapor deposition material in the crucible.

FIG. 16 shows a vacuum deposition apparatus 200 based on the electron beam deposition method. The inside of the vacuum container is a vacuum chamber 201, and in the vacuum chamber 201, an electron beam generator 202, a crucible 204, a holder 208, and the like are installed. A vapor deposition material 206 is placed in the crucible 204 . A dome-shaped retainer 208 holds a plurality of objects (workpieces) 210 . An electron beam 212 is generated in the electron beam generator 202 and applied to the vapor deposition material 206 . This causes vapor deposition material 206 to evaporate (see reference numeral 214). As a result, vapor deposition layers are formed on the surfaces of the plurality of objects 210 .

A turntable holding a plurality of crucibles may be arranged in the vacuum chamber 201 . In that case, the vapor deposition material to be irradiated with the electron beam is selected by changing the rotation angle of the turntable. In order to efficiently or stably form a good deposited layer, it is desirable to improve the quality of the electron beam 212 (especially the beam shape and thermionic electron density).

FIG. 2 shows a perspective view of a filament assembly 300 according to the first example. The two filament legs of filament 26 are surrounded by two sheaths 40,42. The pedestal pair 18 consists of two pedestals 18R and 18L aligned in the x direction.

A bolt is provided across the two blocks 22R and 24R aligned in the y direction to fasten them, but the illustration thereof is omitted. A clamp mechanism 320 is composed of the two blocks 22R and 24R and the bolts that fasten them. A bolt is provided across the two blocks 22L and 24L aligned in the y direction to fasten them, but the illustration thereof is also omitted. A clamp mechanism 322 is composed of the two blocks 22L and 24L and the bolts that fasten them.

The clamping mechanism 320 is a mechanism for clamping the sheath 40 and the clamping mechanism 322 is a mechanism for clamping the sheath 42 . Each of the blocks 22R, 24R, 22L, 24L is formed with a V-shaped groove 44 for clamping. Other mechanisms or other structures may retain the sheaths 40,42. Incidentally, the two clamping mechanisms 320, 322 are electrically isolated from each other.

FIG. 3 shows the front of the filament assembly 300 according to the first example. The filament 26 is composed of a filament body 46 and two filament legs 48,50. The filament 26 is manufactured, for example, by molding a linear member having a predetermined diameter. That is, in embodiments, filament body 46, filament legs 48, and filament legs 50 have a uniform cross-sectional shape (circular) and a uniform cross-sectional shape, respectively, except for some bends introduced during filament forming. have a size. However, the cross-sectional shape and cross-sectional size of the filament main body 46 may be different from the cross-sectional shape and cross-sectional size of the filament legs 48 and 50 . A filament leg 48 extends from one end of the filament body 46 and a filament leg 50 extends from the other end of the filament body 46 .

The filament body 46 has a solenoidal, ie coiled or helical, configuration with its central axis 68 parallel to the x-direction. The central axis 68 is orthogonal to the beam extraction direction. The number of turns of the filament body 46 is, for example, within the range of 5-10. Filament bodies having other configurations that are not solenoidal may be employed. For example, a straight filament body, a spiral filament body, a plate-like filament body, and the like can be employed.

The length 46A of the filament body 46 in the x direction is set within 9 to 20 mm, for example. Its length 46A may be 12 mm. The height (z-direction size) of the entire filament 26 is set within a range of 14 to 30 mm, for example. For example, the height may be 17 mm.

A filament leg 48 is connected to one end (right end) of the filament main body 46 . A filament leg 50 is connected to the other end (left end) of the filament main body 46 . In the illustrated configuration, the two filament legs 48 and 50 extend in a direction orthogonal to the central axis 68 of the filament body 46 (that is, in the z-direction). One end and the other end of the filament body 46 are spaced apart in the x-direction.

The filament body 46 has a constant extent in the z-direction. The level of its lower edge is indicated by z1. In the illustrated filament 26, the portions below level z1 are defined as filament legs 48,50. In the case where the filament body has a simple linear form or the filament body has a spiral form, two filament legs can be defined with reference to the filament body in the same manner as described above.

In the illustrated configuration example, the filament legs 48 and the filament legs 50 have the same shape as each other, except for some. First, the filament legs 48 are detailed.

The filament leg 48 is roughly divided into a held portion 62 and an exposed portion 63 connected thereto. The held portion 62 is a portion held by the sheath 40 . The bare portion 63 is a portion that is not in contact with other members. The exposed portion 63 is composed of a covered portion 64 and an exposed portion 65 connected thereto. The surrounded portion 64 is an intermediate portion surrounded by the sheath 40 in a non-contact manner, in other words, a portion below the opening of the sheath 40 and above a bottom portion 54 described later. The exposed portion 65 is the portion protruding from the sheath 40 . The enclosed portion 64 and the non-retained portion constitute a straight portion.

In filament leg 48, exposed portion 65 constitutes a sloping portion (see reference numeral 65A). In this respect, the configuration of filament legs 48 differs from the configuration of filament legs 50 . In filament leg 50, exposed portion 65 is a straight portion (see 65B).

The filament leg 48 has a central axis U as an imaginary axis. The central axis U is the material axis passing through the center of gravity of each location on the cross section of the filament leg 48 . As lengths along the central axis U, the length of the entire filament leg 48 is indicated by U1, the length of the exposed portion 63 is indicated by U2, and the length of the enclosed portion 64 is indicated by U3. , and the length of the exposed portion 65 is designated U4. U3 is also the length of a tubular portion (surrounding portion) 52, which will be described later.

In an embodiment, most or most of the exposed portion 63, specifically 60% or more thereof, is the enclosed portion 64 in order to improve the quality of the electron beam. Specifically, the ratio of the length U3 of the surrounded portion 64 to the length U2 of the exposed portion 63 is set to 60% or more. In order to further improve the quality of the electron beam, the ratio of the length U3 of the enclosed portion 64 to the length U2 of the exposed portion 63 is set to 80% or more, preferably 85% or more.

The form of the sheath 40 is determined so as to satisfy the above numerical conditions. The entire exposed portion 63 may be the surrounded portion 64 . That is, the above ratio may be 100%. However, in order to avoid contact between the sheath 40 and the filament body 46, it is desirable to set the above ratio to 98% or less or 96% or less.

Filament legs 50 have the same configuration as filament legs 48, with some exceptions, as already described. Specifically, the filament leg 50 is defined as the portion below z1 and is entirely straight. The filament leg 50 is roughly divided into a held portion 62 and an exposed portion 63 , and the exposed portion 63 is composed of an enclosed portion 64 and an exposed portion 65 . Exposed portions 65 of filament legs 50 are parallel to the z-direction (see 65B). In this respect, the configuration of filament legs 50 differs from that of filament legs 48 .

The filament leg 50 has a central axis V as a virtual axis. The central axis V corresponds to the material axis as described above. Along the central axis V the length of each portion is defined. The length of the entire filament leg 50 is designated V1. In the filament leg 50, the length of the exposed portion 63 is indicated by V2, the length of the enclosed portion 64 is indicated by V3, and the length of the exposed portion 65 is indicated by V4.

In the embodiment, from the viewpoint of improving the quality of the electron beam, the same numerical conditions as the above numerical conditions are applied to the filament leg 50 as well. That is, the ratio of the length U3 of the surrounded portion 64 to the length U2 of the exposed portion 63 is set to 60% or more. In order to further improve the quality of the electron beam, the ratio of the length U3 of the enclosed portion 64 to the length U2 of the exposed portion 63 is set to 80% or more, preferably 85% or more. The form of the sheath 42 is determined so that the above numerical conditions are satisfied.

In order to suppress the outflow of heat through the held portion 62, the ratio of the length of the held portion 62 to the length of the entire filament legs 48, 50 may be 30% or less or 20% or less. In that case, the lower limit of the ratio may be 5% or more or 10% or more.

Next, the sheath 40 and the sheath 42 will be detailed. Sheath 40 and sheath 42 have the same configuration as each other. The sheath 42 will be described as a representative of them.

The sheath 42 is an attachment member. The sheath 42 has a tubular shape as a whole. The sheath 42 is made of a material that can withstand high temperatures, such as metal or ceramic. Specifically, the sheath 42 is made of stainless steel. Sheath 42 may be constructed of tungsten. The outer surface of sheath 42 is a cylindrical surface.

The sheath 42 is composed of a tubular portion 52 and a bottom portion 54 . In practice, the sheath 42 is constructed in a single piece, ie the tubular portion 52 and the bottom portion 54 are integral. The tubular portion 52 and the bottom portion 54 may be separated and joined together.

The tubular portion 52 functions as an enclosing portion. The tubular portion 52 surrounds the enclosed portion 64 of the filament leg 50 in a non-contact manner. In the illustrated configuration example, the enclosed portion 64 can also be referred to as an intermediate portion. Both the outer surface and the inner surface of the tubular portion 52 are cylindrical surfaces. The inner surface of the tubular portion 52 faces the internal space 58 .

The thickness of the tubular portion 52 is set, for example, within a range of 0.1 to 4 mm, and is 0.3 mm in the illustrated configuration example. The inner diameter of the cylindrical portion is set, for example, within a range of 1 to 4 mm, and is 1.5 mm in the illustrated configuration example. The outer diameter of the tubular portion is set, for example, within a range of 2 to 12 mm, and is 2.1 mm in the illustrated configuration example. The distance between the surface of the filament leg 50 and the inner surface of the tubular portion 52 (see reference numeral 70) is set, for example, within the range of 0.1 to 1.6 mm, and in the configuration example shown, it is 0.35 mm. is. The length of the exposed portion 63 is set within a range of 10 to 30 mm, for example, and the length of the enclosed portion 64 is set within a range of 6 to 30 mm, for example. In any case, each length is determined so that the above numerical conditions are satisfied. The width of the exposed portion 65 in the z-direction, that is, the gap between the filament body 46 and the sheaths 40, 42 is set within a range of 0.5 to 2.5 mm, for example.

Bottom 54 is the bottom wall of sheath 42, which acts as a retainer. The bottom portion 54 has a disk-like shape, and a holding hole 60 is formed in the center thereof. A non-holding portion (lower end portion) 62 of the filament leg 50 is detachably inserted into the holding hole 60 , and the held portion 62 is held by the bottom portion 54 . The held portion 62 and the inner surface of the holding hole 60 may be fixed. Filament 26 and sheath 42 (and sheath 40) may be integrated.

The portion of the filament leg 50 that is housed in the inner space 58 of the tubular portion 52 is the enclosed portion 64 . The tubular portion 52 has an embedded portion 56 that exists below the upper surface of the block 24L, and a protruding portion 55 that protrudes above the upper surface of the block 24L. In the illustrated configuration example, the projecting portion 55 extends to the vicinity of the filament body 46 . This satisfies the above numerical conditions.

Sheath 42 is configured such that sheath 42 does not contact filament 26 except at bottom 54 . From the viewpoint of raising the temperature of the filament main body 46 or making the temperature distribution uniform, it is better to increase the ratio of the lengths U3 and V3 of the enclosed portion to the lengths U2 and V2 of the exposed portion 63. , 42 and the filament 26, it is desired that the ratio is less than 100%.

In order to suppress heat flow from the sheaths 40, 42 to the blocks 24R, 24L (and the blocks 22R, 22L shown in FIG. 2), etc., the thickness of each block in the z direction may be reduced.

As already explained, sheath 40 has the same configuration as sheath 42 . A large number of sheaths having the same configuration may be manufactured and any two of them may be used as the sheath 40 and the sheath 42 . Each sheath 40, 42 is held by four V-groove inner surfaces 44A, respectively.

4 is a right side view showing one filament leg 48 of filament 26. FIG. The filament body 46 has a helical form and its outer shape is close to a cylinder. Filament legs 48 include straight portions 48a and angled portions 48b. The straight portion 48a and the inclined portion 48b are connected via a bent portion 48c. The straight portion 48a corresponds to the surrounded portion 64 and the held portion. The inclined portion 48b is the exposed portion 65 (65A). The inclined portion 48b is a connecting portion that connects the straight portion 48a to the filament body 46. As shown in FIG.

The length U2 of the exposed portion 63 corresponds to the sum of the length U3 of the surrounded portion 64 and the length U4 of the inclined portion 48b (exposed portion 65). The upper end level of the sheath 40 is located at or near the bent portion 48c. FIG. 4 shows thermal electrons R emitted from the enclosed portion 64 . Thermal electrons R are blocked by the inner surface of the sheath 40 . This prevents the quality of the electron beam from deteriorating due to the thermal electrons R. FIG.

5 is a right side view showing the other filament leg 50 of filament 26. FIG. In FIG. 5, elements that have already been described are given the same reference numerals. The entire filament leg 50 is straight. Filament leg 50 has a bare portion 63 which is composed of an enclosed portion 64 and an exposed portion 65 . The ratio of the length V3 of the surrounded portion 64 to the length V2 of the exposed portion 63 satisfies the above numerical conditions. In the filament leg 50 as well, the thermal electrons R emitted from the enclosed portion 64 are blocked by the sheath 42 to prevent deterioration of the quality of the electron beam due to the thermal electrons R.

In the configuration according to the above embodiment, the radiant energy emitted from each enclosed portion of each filament leg reaches the inner surface of each sheath. Heat conduction also provides heat from each filament leg to each sheath. This increases the temperature of each sheath. At the same time, the temperature of each filament leg rises, and heat outflow via each filament leg is suppressed. As a result, the temperature of the filament body is increased or the temperature distribution there is homogenized. This improves the quality of the electron beam.

In the filament assembly according to the first example, since the tubular portion and the bottom portion are integrated in each sheath, heat conduction from the bottom portion to the tubular portion is promoted. In addition, the filament is detachably held by two holding holes formed in the two bottoms, so there is no need to provide a complicated structure for holding the filament. The central axis of each filament leg coincides with the central axis of each cylindrical portion.

FIG. 6 shows a filament assembly 302 according to a second example. FIG. 6 shows a horizontal cross-section of filament assembly 302 . A rectangular well 72A is formed in the block 72 when viewed in the z-direction, and a rectangular well 74A is also formed in the block 74 when viewed in the z-direction. A rectangular sheath 76 is partially inserted in the well 72A, and a rectangular sheath 78 is partially inserted in the well 74A. Enclosed within each sheath 76, 78 is an enclosed portion of each filament leg 49R, 49L. Thus, prismatic sheaths 76, 78 may be employed.

FIG. 7 shows a filament assembly 304 according to a third example. A block 82 is mounted on a pedestal 80 and a block 84 is mounted on a pedestal 81 . A through hole is formed in the block 82 and a cylindrical sheath 86 is inserted therein. Similarly, the block 84 is formed with a through hole into which a tubular sheath 88 is inserted. The lower end faces of the sheaths 86,88 abut against the upper faces of the pedestals 80,81. Filament 90 has filament legs 92,94. The pedestal 80 has a holding hole 96 for holding a held portion (end portion) 92A of the filament leg 92 . The pedestal 81 has a holding hole 98 for holding the held portion (end) 94A of the filament leg 94 . The end surfaces of the held portions 92A and 94A abut against the bottom surfaces of the holding holes 96 and 98, respectively.

Each sheath 86, 88 is configured to satisfy the above numerical conditions. That is, in each filament leg 92, 94, the ratio of the lengths U3, V3 of the covered portion 64 to the lengths U2, V2 of the exposed portion 63 is 60% or more, preferably 80% or more.

FIG. 8 shows a filament assembly 306 according to a fourth example. Filament 110 has filament legs 112 and 114 . A block 102 is mounted on a pedestal 100 and a block 104 is mounted on a pedestal 101 . Well 106 is formed in block 102 and well 108 is formed in block 104 . A through hole is formed in the bottom portion 102B of the well 106, and the held portion (end portion) 112A of the filament leg 112 is inserted into the through hole. A through hole is formed in the bottom portion 104B of the well 108, and the held portion (end portion) 114A of the filament leg 114 is inserted into the through hole. Each through hole functions as a holding hole.

At blocks 102 and 104, portions 102A and 104A surrounding wells 106 and 108 respectively function as enclosures. Bottom portions 102B and 104B of blocks 102 and 104 function as holding portions. The portions 102A, 104A surrounding the wells 106, 108 are hot spots, which in turn raises the temperature of the filament legs 112, 114 and reduces heat flow therefrom. The interior of the wells 106, 108 define two cavities 106A, 108A through which the enclosed portions of the two filament legs 112, 114 pass.

In the configuration according to the fourth example, the blocks 102 and 104 as structural bodies function as the surrounding portion and the holding portion as described above. Additionally, blocks 102 and 104 may function as clamping members.

Each block 102, 104 is constructed so as to satisfy the above numerical conditions. That is, in each filament leg 112, 114, the ratio of the lengths U3, V3 of the covered portion 64 to the lengths U2, V2 of the exposed portion 63 is 60% or more, preferably 80% or more.

FIG. 9 shows a filament assembly 308 according to a fifth example. Filament 120 has a filament body 122 and filament legs 124,126. Filament legs 124 , 126 extend from opposite ends of filament body 122 to opposite sides of filament body 122 . Specifically, the central axis of each filament leg 124 , 126 is parallel to the central axis of filament body 122 .

Sheaths 128, 130 are formed by tubular portions 136, 140 and bottom portions 138, 142, respectively. The held portions (ends) 124A, 126A of the filament legs 124, 126 are held by bottoms 138, 142 as holding portions. Enclosed portions of filament legs 124 and 126 pass through tubular sections 136 and 140 . The sheaths 128,130 are retained by blocks 132,134.

In the configuration according to the fifth example as well, each sheath 128, 130 is configured so as to satisfy the above numerical conditions. That is, in each filament leg 124, 126, the ratio of the lengths U3, V3 of the covered portions to the lengths U2, V2 of the exposed portions is 60% or more, preferably 80% or more. The complicated portion (helical portion) with an increased surface area is the filament main body 122, and the two straight portions drawn out from both ends thereof are the two filament legs 124 and 126. FIG.

FIG. 10 shows a first variant of the filament. Elements that have already been described are denoted by the same reference numerals, and description thereof will be omitted. This also applies to FIG. 11, which will be described later.

In FIG. 10, the ends of the two filament legs in filament 26A have an L-shaped configuration. Specifically, the ends of filament legs 150 pass through retention holes 60 formed in bottom 54 of sheath 40 . The end portion is composed of a first portion 150d connected to the portion to be surrounded and a second portion 150e connected to the first portion 150d. The first portion 150d is parallel to the z-direction and the second portion is parallel to the y-direction. There is a bend between them. In the configuration shown in FIG. 10, the first portion 150d is the held portion. The entire end portion may be the portion to be held.

The entire filament leg may be L-shaped. In that case, the end portion may be L-shaped in the same manner as described above.

FIG. 11 shows a modification of the sheath (attachment member). The bipartite sheath 152 is comprised of a first portion 152a and a second portion 152b. A groove 154a is formed in the bottom of the first portion 152a, and a groove 154b is formed in the bottom of the second portion 152b. The combination of the first portion 152a and the second portion 152b constitutes the sheath 152, in which the held portion of the filament leg 150 is held by the two grooves 154a, 154b. The two grooves 154a, 154b function as retaining holes 154 in their combined state.

FIG. 12 shows a modification of the filament holding structure. The connection of blocks 156 and 158 holds filament legs 150 of filament 26A. The other filament leg is held by a similar structure.

Block 156 has a semi-cylindrical depression 160A and a groove 164A. Block 158 also has a semi-cylindrical depression 160B and also has a groove 164B. The connection of block 156 and block 158 retains filament legs 150 .

Specifically, in the coupled state, the two grooves 164A and 164B are combined to function as holding holes, and the held portion of the filament leg 150 is held by the two grooves 164A and 164B. In the bonded state, the two recesses 160A, 160B combine to form a cavity 160 that accommodates the enclosed portion of the filament leg 150. FIG. The periphery of the cavity 160 functions as an enclosure. The lower portion of cavity 160 functions as a retainer.

FIG. 13 shows a modified filament. The illustrated filament 166 has a straight filament body 168 and two filament legs 170, 172 extending from each end thereof. Filament body 168 extends in the x-direction and each filament leg 170, 172 extends in the z-direction. The cross section of the filament body 168 has, for example, a semicircular shape, a D shape, a flat plate shape, or the like. In this variant, the main part that emits thermionic electrons is the part parallel to the x-direction, which is the filament body 168 . That is, the range indicated by reference numeral 174 corresponds to the filament body 168 in the z direction. The remaining portions, specifically the two portions within the range indicated by reference numeral 175, are filament legs 170,172. Two sheaths are attached to the two filament legs 170,172.

FIG. 14 shows an electron beam generator for vapor deposition according to the second embodiment. In the first embodiment, a vertical filament is installed in the electron beam generator, but in the second embodiment, a horizontal filament 26 is installed in the electron beam generator. A clamping mechanism 184 holds two sheaths 40, 42 in a horizontal orientation. The two sheaths 40, 42 surround the wrapped portions of the two filament legs and retain the retained portions of the two filament legs. Reference numeral 30 indicates an anode electrode for extracting thermionic electrons, and reference numeral 186 indicates a beam shaping electrode. The beam extraction direction is the -y direction. Reference numeral 38 indicates an electron beam.

Also in the second embodiment, the sheaths 40 and 42 are provided so as to satisfy the above numerical conditions. As a result, the temperature of the filament body can be raised, or the temperature distribution can be made uniform, so that the quality of the electron beam can be improved.

FIG. 15 shows a comparative example. Filament 220 is composed of tungsten and it is placed in the vacuum chamber. Oxygen gas is introduced into the vacuum chamber. That is, filament 220 is in an oxygen atmosphere.

Filament 220 is comprised of a filament body 222 and two filament legs 224,226. The filament leg 224 is sandwiched by the right block pair (only one block 228 of the right block pair is shown in FIG. 16), and the filament leg 226 is sandwiched by the left block pair (see FIG. 16). Only one block 230 of the left block pair is shown in FIG. 16). The filament body 222 is the hot section. A temperature gradient is created in the exposed portion of each filament leg 224,226. In particular, at the intermediate portions 232, 234 of each exposed portion, an intermediate temperature that tends to oxidize occurs. The melting point of tungsten oxide is lower than that of tungsten, and the oxidized portion evaporates, promoting the thinning of the intermediate portions 232 and 234 . If the oxidation proceeds further, the intermediate portions 232, 234 will break.

According to the configuration according to the embodiment, the exposed portion of each filament leg is surrounded by the surrounding portion to increase the temperature of the entire filament leg. This effectively avoids the occurrence of the above intermediate temperature. That is, filament life can be increased. Experiments have confirmed that filament life can be increased by a factor of three.

According to the configuration according to the embodiment, it is possible to improve the quality of the electron beam. The advantage is obtained with or without oxygen in the vacuum chamber. In particular, the advantage of increasing the temperature of the filament body or uniformizing the temperature distribution can be obtained in both the configuration according to the first embodiment and the configuration according to the second embodiment. The configuration according to the embodiment may be applied to other electron beam generators.

10 electron beam generator, 26 filament, 38 electron beam, 40, 42 sheath, 46 filament main body, 48, 50 filament leg, 52 cylindrical part (surrounding part), 54 bottom part (holding part).

Claims (10)

a filament having a filament body, a first filament leg connected to one end of the filament body, and a second filament leg connected to the other end of the filament body;
a first holding portion that holds the first held portion of the first filament leg;
a second holding portion that holds a second held portion of the second filament leg;
a first enveloping portion having a cylindrical shape enclosing, in a non-contact manner, a first enveloping portion of the first filament leg that is closer to the filament main body than the first held portion;
a second enveloping portion having a cylindrical shape enclosing, in a non-contact manner, a second enveloping portion of the second filament leg that is closer to the filament main body than the second held portion;
including
a first exposed portion between the first held portion and one end of the filament body in the first filament leg;
a second exposed portion between the second held portion and the other end of the filament body in the second filament leg;
A ratio of the length of the first surrounded portion to the length of the first exposed portion is 60% or more,
A ratio of the length of the second surrounded portion to the length of the second exposed portion is 60% or more,
An electron beam generator for vapor deposition characterized by: The electron beam generator for vapor deposition according to claim 1,
A ratio of the length of the first surrounded portion to the length of the first exposed portion is 80% or more,
A ratio of the length of the second surrounded portion to the length of the second exposed portion is 80% or more,
An electron beam generator for vapor deposition characterized by: a filament having a filament body, a first filament leg connected to one end of the filament body, and a second filament leg connected to the other end of the filament body;
a first holding portion that holds the first held portion of the first filament leg;
a second holding portion that holds a second held portion of the second filament leg;
a first enveloping portion that encloses, in a non-contact manner, a first enveloping portion of the first filament leg that exists closer to the filament main body than the first held portion;
a second enveloping portion that encloses, in a non-contact manner, a second enveloping portion of the second filament leg that exists closer to the filament main body than the second held portion;
including
a first exposed portion between the first held portion and one end of the filament body in the first filament leg;
a second exposed portion between the second held portion and the other end of the filament body in the second filament leg;
A ratio of the length of the first surrounded portion to the length of the first exposed portion is 60% or more,
A ratio of the length of the second surrounded portion to the length of the second exposed portion is 60% or more,
The first enclosing part has a cylindrical shape that absorbs heat radiated from the first enclosing part and blocks thermal electrons emitted from the first enclosing part,
The second enclosing part has a cylindrical shape that absorbs heat radiated from the second enclosing part and blocks thermoelectrons emitted from the second enclosing part,
An electron beam generator for vapor deposition characterized by: In the electron beam generator for vapor deposition according to claim 3,
a first clamping mechanism for clamping the first enclosing part;
a second clamping mechanism for clamping the second enclosing part;
An electron beam generator for vapor deposition, comprising: a filament having a filament body, a first filament leg connected to one end of the filament body, and a second filament leg connected to the other end of the filament body;
a first holding portion that holds the first held portion of the first filament leg;
a second holding portion that holds a second held portion of the second filament leg;
a first enveloping portion that encloses, in a non-contact manner, a first enveloping portion of the first filament leg that exists closer to the filament main body than the first held portion;
a second enveloping portion that encloses, in a non-contact manner, a second enveloping portion of the second filament leg that exists closer to the filament main body than the second held portion;
including
a first exposed portion between the first held portion and one end of the filament body in the first filament leg;
a second exposed portion between the second held portion and the other end of the filament body in the second filament leg;
A ratio of the length of the first surrounded portion to the length of the first exposed portion is 60% or more,
A ratio of the length of the second surrounded portion to the length of the second exposed portion is 60% or more,
The first holding portion and the first enclosing portion are integrated,
The second holding portion and the second enclosing portion are integrated,
An electron beam generator for vapor deposition characterized by: In the electron beam generator for vapor deposition according to claim 5,
A first attachment member is configured by the first holding portion and the first surrounding portion,
A second attachment member is configured by the second holding portion and the second enclosing portion,
The first attachment member and the second attachment member have the same shape as each other,
An electron beam generator for vapor deposition characterized by: The electron beam generator for vapor deposition according to claim 1,
The first holding part and the first enclosing part are a first structure having a first cavity through which the first enclosed part passes,
the first structure absorbs heat emitted from the first enclosed portion and blocks thermal electrons emitted from the first enclosed portion;
The second holding part and the second enclosing part are a second structure having a second cavity through which the second enclosed part passes,
the second structure absorbs heat emitted from the second enclosed portion and blocks thermal electrons emitted from the second enclosed portion;
An electron beam generator for vapor deposition characterized by: The electron beam generator for vapor deposition according to claim 1,
The first filament leg has a first straight portion including the first surrounded portion and an inclined portion connected to the first straight portion via a bent portion,
the second filament leg has a second straight portion that includes the second enclosed portion;
The first enclosing portion extends to or near the bent portion,
The length of the first enclosing part and the length of the second enclosing part are the same,
An electron beam generator for vapor deposition characterized by: an enclosure for contactlessly enclosing filament legs in the filament that produces the electron beam;
The enclosing part has a hollow shape extending in the central axis direction of the filament legs,
The filament leg is composed of a held portion and an exposed portion connected thereto,
The surrounding portion surrounds the surrounding portion connected to the held portion in the exposed portion,
A ratio of the length of the enclosed portion to the length of the exposed portion is 60% or more,
An attachment member for an electron beam generator, characterized by: The attachment member according to claim 9,
a bottom integral with the enclosure;
the bottom portion has a holding hole into which the held portion is inserted;
An attachment member for an electron beam generator, characterized by:

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