JP2011210426A - LaB6 FILM AND CATHODE BODY, AND METHOD OF MANUFACTURING THEM - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that an LaBfilm is easy to separate when the LaBfilm is formed on a substrate as a base by a magnetron sputtering device which can use a target uniformly over a long period and improve a film forming rate.SOLUTION: The surface of the substrate is nitrided, followed by the LaBfilm formed on the nitrided surface of the substrate by sputtering in the same processing device. Thus, the LaBfilm can be formed which is hard to separate from the substrate.

Description

The present invention relates to a LaB ₆ film, a cathode body having a LaB ₆ film, and a method for producing them.

In general, a boride film containing a rare earth element such as LaB ₆ is used in a cold cathode fluorescent tube including a cathode body. Cold cathode fluorescent tubes including a cathode body are used as backlight light sources for liquid crystal display devices in monitors, liquid crystal televisions, and the like. The cold cathode fluorescent tube includes a fluorescent tube body formed of a glass tube and coated with a phosphor on the inner wall, and a pair of cold electrode bodies that emit electrons, and the fluorescent tube body includes a mixed gas such as Hg-Ar. Is enclosed.

Patent Document 1 proposes a cold cathode fluorescent tube including a cold cathode body having a cylindrical cup shape. Specifically, a cylindrical cup-shaped cold cathode body for electron emission is mainly composed of a rare earth element boride on a cylindrical cup formed of nickel and inner and outer wall surfaces of the cylindrical cup. It has an emitter layer. Further, Patent Document 1 exemplifies YB ₆ , GdB ₆ , LaB ₆ , and CeB ₆ as rare earth element borides, and these rare earth element borides are adjusted to a fine powder slurry and are cylindrical. It is formed by pouring, drying and sintering on the inner and outer wall surfaces of the cup.

On the other hand, in Patent Document 2, a cold cathode body having a cylindrical cup shape is formed by mixing a material selected from La ₂ O ₃ , ThO ₂ , and Y ₂ O ₃ with a material having high thermal conductivity, for example, tungsten. Is disclosed. The cylindrical cup-shaped cold cathode body disclosed in Patent Document 2 is formed by, for example, injection molding, that is, MIM (Metal Injection Molding), of a tungsten alloy powder containing La ₂ O ₃ .

Furthermore, patent document 3 is disclosing the discharge cathode apparatus used for a plasma display panel. The discharge cathode device has an aluminum layer formed as a base electrode on a glass substrate, and a LaB ₆ layer formed on the aluminum layer. The aluminum layer is formed on a glass substrate kept at a predetermined temperature by a sputtering method, a vacuum evaporation method, or an ion plating method, while the LaB ₆ layer is formed on the aluminum layer by a sputtering method or the like. Yes.

  In Patent Document 1, an emitter layer is formed by applying a slurry mainly composed of rare earth elements to a cylindrical cup made of Ni (nickel), drying, and sintering.

  Patent Document 1 discloses that the emitter layer is thinned on the opening end side of the cylindrical cup and thickened on the external extraction electrode side. Usually, since the cylindrical cup has an inner diameter of about 0.6 to 1.0 mm and a length of about 2 to 3 mm, an emitter layer is formed by a method of applying slurry, drying and sintering. In this case, it is difficult to apply to a desired thickness. Furthermore, the emitter layer obtained by coating, drying and sintering is insufficient in terms of adhesion to Ni, and it is difficult to completely remove organic substances, moisture and oxygen contained in the binder. As a result, in Patent Document 1, it is difficult to obtain a cold cathode body with high brightness and long life.

In Patent Document 2, a cylindrical cup-shaped cold cathode body is formed by injection-molding a pellet obtained by mixing tungsten alloy powder containing La ₂ O ₃ with a resin such as styrene into a mold. By using a material having high thermal conductivity such as tungsten, the heat conduction in the cold cathode body can be improved, but the life of the cold cathode body can be extended, but the electron emission characteristics are insufficient. Therefore, in Patent Document 2, it is difficult to obtain a cold cathode body with high luminance and high efficiency.

Patent Document 3 discloses that a discharge cathode pattern including a LaB ₆ layer and aluminum is formed on a glass substrate by a sputtering method. However, this method is based on the premise that an aluminum layer and a LaB ₆ layer are formed on a flat glass substrate by sputtering, and there is no disclosure about a method of sputtering on an uneven cylindrical cup-shaped cold cathode body. Further, Patent Document 3, a material other than glass substrate, without using aluminum, does not disclose the adhesion good form LaB ₆ layers. Furthermore, patent document 3 does not point out improving the electron emission efficiency in the cold cathode body having a cylindrical cup shape.

  Therefore, it has been proposed to form a rare earth element boride film by sputtering using a rotating magnet type magnetron sputtering apparatus (Patent Document 4).

JP-A-10-144255 WO2004 / 075242 JP-A-5-250994 WO / 2009/035074

  The inventors of the present invention can prevent the local wear of the target by moving the ring-shaped plasma region on the target with time, increase the plasma density, and improve the deposition rate. We proposed a magnetron sputtering system. The magnetron sputtering apparatus has a configuration in which a target is disposed to face a substrate to be processed, and a magnet member is provided on the opposite side of the target from the substrate to be processed.

  More specifically, the magnet member of the magnetron sputtering apparatus described above includes a rotating magnet group in which a plurality of plate magnets are spirally attached to the surface of the rotating shaft, a parallel to the target surface around the rotating magnet group, and And a fixed outer peripheral plate magnet magnetized perpendicularly to the target. According to this configuration, by rotating the rotating magnet group, the magnetic field pattern formed on the target by the rotating magnet group and the fixed outer peripheral plate magnet is continuously moved in the direction of the rotation axis. The plasma region can be continuously moved in the direction of the rotation axis with time.

  By using the magnetron sputtering apparatus, the target can be used uniformly over a long period of time, and the film formation rate can be improved.

  If such a rotating magnet type magnetron sputtering apparatus is used, a film can be easily formed even in the shape of a cylindrical cup, but the film is likely to peel off, that is, there is a problem in the adhesion between the underlying surface and the film. found.

  Accordingly, one technical problem of the present invention is to provide a cathode body having a rare earth element boride film that has good adhesion to the substrate surface and is difficult to peel off.

  Another technical problem of the present invention is to provide a method for forming a LaB6 film that has good adhesion to the surface of the underlying substrate and is difficult to peel off.

  That is, according to one aspect of the present invention, a base, a nitride layer of a component of the base provided on the surface of the base, and a rare earth element boron formed by sputtering on the surface of the nitride layer. A cathode body characterized by having a fluoride film is obtained.

The substrate may be tungsten or molybdenum containing at least one selected from the group consisting of tungsten, molybdenum, silicon, La ₂ O ₃ , ThO ₂ , and Y ₂ O ₃ , a resin, glass, or silicon oxide. In particular, it may be tungsten or molybdenum containing 4-6% La ₂ O ₃ by volume.

The rare earth element boride may be at least one boride selected from the group consisting of LaB ₄ , LaB ₆ , YbB ₆ , GaB ₆ , and CeB ₆ .

According to the present invention, the method further comprises a step of nitriding the surface of the substrate and a step of subsequently forming a LaB ₆ film on the nitrided surface of the substrate by sputtering in the same processing apparatus. A method for producing a LaB ₆ film is obtained. The substrate may be tungsten, molybdenum, silicon, tungsten or molybdenum containing 4 to 6 wt% lanthanum oxide, resin, glass, or silicon oxide.

  According to the present invention, a boride film having good adhesion to the base can be obtained.

It is the schematic which shows the magnetron sputtering device used when manufacturing the cathode body which concerns on this invention. It is sectional drawing which expands and shows a part of FIG. (A) ~ (F) is an exemplary embodiment of the present invention, is a cross-sectional view showing a process in order to form the LaB ₆ film by using the apparatus of FIG. By another embodiment of the present invention, the substrate surface is nitrided, a cross-sectional view showing an apparatus for forming a LaB ₆ film.

  An embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 is a view showing an example of a rotating magnet type magnetron sputtering apparatus used in the present invention, and FIG. 2 is for explaining a cathode body manufacturing jig used for manufacturing the cathode body according to the present invention. FIG.

  The magnetron sputtering apparatus shown in FIG. 1 includes a target 1, a polygonal (for example, regular hexagonal) columnar rotating shaft 2, and a plurality of helical plate magnets that are spirally attached to the surface of the columnar rotating shaft 2. The rotating magnet group 3 including the group and the fixed outer peripheral plate magnet 4 and the fixed outer peripheral plate magnet 4 disposed on the outer periphery of the rotating magnet group 3 so as to surround the rotating magnet group 3 are provided on the side opposite to the target 1. The outer peripheral paramagnetic material 5 is provided. Further, a backing plate 6 is bonded to the target 1, and portions other than the columnar rotating shaft 2 and the spiral plate magnet group 3 other than the target 1 side are covered with a paramagnetic material 15. Covered by.

  When viewed from the target 1, the fixed outer peripheral plate magnet 4 has a structure surrounding the rotating magnet group 3 constituted by a spiral plate magnet group, and is magnetized so that the side of the target 2 becomes an S pole. . The fixed outer peripheral plate magnet 4 and each plate magnet of the spiral plate magnet group are formed of Nd—Fe—B based sintered magnets.

  Furthermore, a plasma shielding member 16 is provided in the illustrated space 11 in the processing chamber, a cathode body manufacturing jig 19 is installed, and the pressure is reduced to introduce plasma gas.

  The illustrated plasma shielding member 16 extends in the axial direction of the columnar rotating shaft 2, and defines a slit 18 that opens the target 1 to the cathode manufacturing jig 19. In a region that is not shielded by the plasma shielding member 16 (that is, a region that is opened with respect to the target 1 by the slit 18), a high-density, low-electron temperature plasma is generated with a strong magnetic field strength, and a cathode manufacturing jig 19. This is a region where charge-up damage and ion irradiation damage do not occur in the cathode member provided in the region, and at the same time, a region where the film formation rate is high. By shielding the region other than this region with the plasma shielding member 16, it is possible to perform film formation without damage without substantially reducing the film formation rate.

  The backing plate 6 is formed with a refrigerant passage 8 through which a refrigerant passes, and an insulating material 9 is provided between the housing 7 and the outer wall 14 forming the processing chamber. The feeder line 12 connected to the housing 7 is drawn to the outside through the cover 13. A DC power source, an RF power source, and a matching unit (not shown) are connected to the feeder line 12.

  In this configuration, plasma excitation power is supplied from the DC power source and the RF power source to the backing plate 6 and the target 1 through the matching unit, the feeder line 12 and the housing, and the plasma is excited on the surface of the target 1. Plasma excitation is possible with only DC power or RF power alone, but it is desirable to apply both from the viewpoint of film quality controllability and film deposition rate controllability. The frequency of the RF power is usually selected from several hundred kHz to several hundred MHz, but a high frequency is desirable from the viewpoint of high density and low electron temperature of the plasma. In this embodiment, a frequency of 13.56 MHz is used. ing.

  As shown in FIG. 1, a plurality of cylindrical cups 30 forming a cathode body are attached to a cathode body manufacturing jig 19 installed in a space 11 in a processing chamber.

  Referring also to FIG. 2, the cathode body manufacturing jig 19 has a plurality of support portions 32 that support the cylindrical cup 30. Here, as shown in FIG. 2, the cylindrical cup 30 was pulled out from the cylindrical electrode part 301 and the center of the bottom of the cylindrical electrode part 301 in the opposite direction to the cylindrical electrode part 301. In this example, it is assumed that the cylindrical electrode portion 301 and the lead portion 302 are integrally formed by MIM (Metal Injection Molding) or the like.

  The support part 32 of the cathode body manufacturing jig 19 includes a receiving part 321 that defines an opening having a size for receiving the cylindrical electrode part 301 of the cylindrical cup 30, and a flange part that defines a hole having a smaller diameter than the receiving part 321. 322 and an inclined portion 323 that connects the receiving portion 321 and the flange portion 322. As illustrated, the cylindrical electrode portion 301 is inserted into the support portion 32 of the cathode body manufacturing jig 19. That is, the lead portion 302 of the cylindrical electrode portion 301 passes through the flange portion 322 of the cathode body manufacturing jig 19, and the outer end portion of the cylindrical electrode portion 301 contacts the inclined portion 323 of the cathode body manufacturing jig 19. Yes.

Here, the illustrated cylindrical cup 30 is made of tungsten (W) containing lanthanum oxide (La ₂ O ₃ ) in a volume ratio of 4% to 6%, and has an inner diameter of 1.4 mm, an outer diameter of 1.7 mm, and a length. The cylindrical electrode portion 301 has a thickness of 4.2 mm. On the other hand, the length of the lead portion 302 of the cylindrical cup 30 may be shortened to about 1.0 mm, for example. In this example, the cylindrical cup 30 is formed by mixing La ₂ O ₃ having a work function as small as 2.8 to 4.2 eV with tungsten, which is a refractory metal having good thermal conductivity. By using tungsten, heat generated in the cylindrical cup 30 can be efficiently discharged, and by mixing lanthanum oxide having a small work function, electrons can also be emitted from the cylindrical cup 30 itself. . Note that molybdenum (Mo) may be used in place of tungsten as a metal having high thermal conductivity for forming the cylindrical cup 30.

Here, the manufacturing method of the cylindrical cup 30 is demonstrated concretely. First, a tungsten alloy powder containing 3% La ₂ O ₃ by volume and a resin powder were mixed. Styrene was used as the resin powder, and the mixing ratio of the tungsten alloy powder and styrene was 0.5: 1 by volume. Next, a small amount of Ni was added as a sintering aid to obtain pellets. A cup-shaped molded product is produced by performing injection molding (MIM) on a cylindrical cup-shaped mold at a temperature of 150 ° C. using the pellets thus obtained. The produced molded product was degreased by heating in a hydrogen atmosphere to obtain a cylindrical cup 30.

The cylindrical cup 30 thus obtained is attached to the cathode manufacturing jig 19 shown in FIGS. 1 and 2, and is carried into the processing chamber 11 of the magnetron sputtering apparatus in which a LaB ₆ sintered body is set as the target 1. did.

  Argon was introduced into the processing chamber 11 to a pressure of about 20 mTorr (2.7 Pa), and the temperature of the cathode manufacturing jig 19 was heated to 300 ° C. to perform sputtering.

Returning to FIG. 2, the state of the cylindrical cup 30 after sputtering is schematically shown. As shown in the drawing, a thick LaB ₆ film 341 is formed in a region having an aspect ratio of 1 which is the ratio of the depth and the inner diameter of the cylindrical electrode portion 302, and is further lowered by the cathode manufacturing jig 19. A thin LaB ₆ film 342 is formed in the position. Furthermore, a very thin LaB ₆ film (bottom LaB ₆ film) 343 is formed on the inner bottom surface of the cylindrical electrode portion 302.

In the illustrated example, the thick LaB ₆ film 341, the thin LaB ₆ film 342, and the bottom LaB ₆ film 343 were 300 nm, 60 nm, and 10 nm, respectively.

It has been confirmed by experiments by the present inventors that the cathode body having the LaB ₆ film described above can maintain high efficiency and high brightness over a long period of time.

  The process according to one embodiment of the present invention will now be described with reference to FIG. Here, the process when the rotating magnet type magnetron sputtering apparatus shown in FIG. 1 is used will be described.

First, in the processing chamber 11 of the rotary magnet type magnetron sputtering apparatus schematically shown in FIG. 3, a stage 19 having a substrate to be processed (here, a cylindrical cup 30 serving as a substrate is mounted for the cathode manufacturing process). The tool 19) is introduced (FIG. 3A), and the surface of the cylindrical cup 30 is cleaned before film formation. A LaB ₆ target is attached to the sputtering apparatus. Ar gas is flowed into the processing chamber 11 at 2,000 sccm, and as shown in FIG. 3B, the cathode manufacturing jig 19 is moved to a position facing the target, and the pressure in the processing chamber 11 is set to 270 mTorr. 100 W RF is applied to the target, the target self-bias voltage is set to about minus 100 V, and argon (Ar) plasma is generated (the target voltage is low, so LaB ₆ is hardly sputtered). For seconds. Next, the processing chamber is switched to an Ar atmosphere, and cleaning is completed (FIG. 3C).

Next, as shown in FIG. 3D, the surface of the substrate (cylindrical cup attached to the cathode manufacturing jig 19) is nitrided in the processing chamber 11 of the rotating magnet type magnetron sputtering apparatus. In this case, with the cathode manufacturing jig 19 disposed at a position facing the target, argon to which nitrogen gas (N ₂ ) has been added is introduced, and Ar plasma is generated to nitride the cylindrical cup surface. In the nitriding step, a gas containing nitrogen is turned into plasma to generate active nitrogen, and the surface of the substrate (cylindrical cup) is irradiated with the active nitrogen. As a result, the surface of the substrate is nitrided. Specifically, argon gas added with 25% nitrogen is flowed at a flow rate of 800 sccm (that is, nitrogen gas 200 sccm, Ar gas 600 sccm), the pressure in the processing chamber 11 is set to 100 mTorr, and 100 W RF is applied to the target. The target self-bias voltage was set to about minus 100 V, plasma was generated (LaB ₆ is hardly sputtered because the target voltage is low), and the substrate surface was nitrided for 12 seconds by irradiating with plasma activated nitrogen atoms. Note that the cleaning process of FIGS. 3B and 3C may be omitted, and the process may proceed directly from FIG. 3A to the nitriding process of FIG. 3D.

When the nitriding step is completed, the substrate (in this embodiment, a cathode manufacturing jig with a cylindrical cup attached) 19 is moved to a position away from the target, the inside of the processing chamber 11 is switched to an Ar atmosphere, and plasma is generated. Empty sputtering is performed (FIG. 3E). Since LaB ₆ surface of the target before the nitriding step will be slightly nitrided, to clean the LaB ₆ surface by removing the nitride film of LaB ₆ surface in this empty sputtering process is an object of this process.

Next, as shown in FIG. 3F, the base body (a cathode manufacturing jig with a cylindrical cup attached in this embodiment) 19 was moved to a position facing the target in an Ar atmosphere. In this state, and sputtering was carried out in the LaB ₆ from LaB ₆ target 18 seconds. At this time, sputtering was performed with an Ar gas flow rate of 2,000 sccm, a processing chamber 11 pressure of 50 mTorr, an RF power of 800 W, and a target self-bias value of −200 V to −300 V. At this time, DC of about 340V may be applied. The potential of the substrate is floating, but may be ground potential.

  Note that the cleaning process in FIG. 3E may be omitted, and the process may proceed directly from the nitridation process in FIG. 3D to the sputtering process in FIG.

As a result, a LaB ₆ film was formed on the nitrided cylindrical cup surface by sputtering. It is preferable to anneal after forming the LaB ₆ film by sputtering. The annealing temperature is preferably 400 ° C to 1000 ° C. The annealing time may be 30 minutes or more and 3 hours or less. The atmosphere of annealing is preferably an inert gas.

Moreover, after sputtering the LaB ₆ film may be subjected to plasma oxidation of LaB ₆ film before the annealing. In this plasma oxidation, 3% oxygen gas is added to Kr gas, the total flow rate is 1,000 sccm, the pressure is 200 mTorr, 100 W of RF is applied, and oxidation is performed by plasma for 48 seconds.

  Next, another embodiment of the present invention will be described with reference to the drawings.

  FIG. 4 is a cross-sectional view illustrating the configuration of a plasma processing apparatus according to another embodiment of the present invention. The illustrated plasma processing apparatus includes a substrate preparation chamber 101, a cathode body manufacturing jig 102 on which a cylindrical cup (not shown) is mounted, a substrate take-out chamber 103, and a plasma processing chamber 109. The plasma processing chamber 109 and the substrate preparation chamber 101 are partitioned by a gate valve 104, and the plasma processing chamber 109 and the substrate take-out chamber 103 are partitioned by a gate valve 105.

The plasma processing chamber 109 includes a surface processing unit 106 having a plasma source having parallel plate electrodes, and first and second rotating magnet type magnetron sputtering film forming units 107 and 108. Among these, the surface treatment unit 106 is a unit that excites plasma with a plasma source and performs plasma cleaning on the surface of the cylindrical cup shown in FIG. The first magnetron sputter deposition unit 107 nitrides the surface of the cylindrical cup (that is, the substrate) on the cathode manufacturing jig 102 in an argon (Ar) atmosphere containing nitrogen gas (N ₂ ). On the other hand, the second rotating magnet type magnetron sputtering film forming unit 108 forms a LaB ₆ film in an argon atmosphere.

  The first and second rotating magnet type magnetron sputtering film forming units 107 and 108 shown in the figure show examples in which two sets of magnetron sputtering sources are provided on the upper and lower sides, respectively, but a cylindrical cup as shown in FIG. When processing only one surface of 30, only one of the magnetron sputtering sources may be used and the other may be inoperative. When the substrate to be processed is flat, the substrate is attached to both the front and back surfaces of a flat substrate holding member, and both the upper and lower plasma sources and the magnetron sputtering source are used.

  In the plasma processing chamber 109 shown in this example, the cathode manufacturing jig 102 is transferred from the gate valve 104 to the surface processing unit 106, the first and second magnetron sputtering film forming units 107 and 108, and the gate valve 105. A moving mechanism (not shown) is provided to move to the position. It is possible to move in the opposite direction (return direction) in the middle instead of this one direction. As the moving mechanism, a moving mechanism used in an in-line type plasma processing apparatus can be used.

  In FIG. 4, the plasma processing chamber 109 in which the length from one end defined by the gate valve 104 to the other end defined by the gate valve 105 is at least three times the length of the cathode manufacturing jig 102. Is used. That is, the plasma processing chamber 109 has a length substantially equal to the length of the surface treatment unit 106 having a length substantially equal to the length of the cathode manufacturing jig 102 in the moving direction and the length of the cathode manufacturing jig 102 in the moving direction. The first and second rotating magnet type magnetron sputter film forming units 107 and 108 having a length on the processed cathode manufacturing jig 102 having a length equal to or longer than the length of the cathode manufacturing jig 102 The cylindrical cup has a length determined by a take-out space for waiting for taking out the cylindrical cup into the take-out chamber 103.

  In this plasma processing apparatus, the substrate preparation chamber 101, the plasma processing chamber 109, and the substrate take-out chamber 103 can all be depressurized, and the substrate preparation chamber 101 and the substrate take-out chamber 103 are at atmospheric pressure at the time of substrate preparation and removal. The plasma processing chamber 109 is basically maintained at a reduced pressure except during maintenance. After the cathode manufacturing jig 102 with the cylindrical cup mounted thereon is set in the substrate preparation chamber 101 and the substrate preparation chamber 101 is depressurized, the cathode manufacturing jig 102 opens the gate valve 101 and opens the robot (FIG. (Not shown) is introduced into the surface treatment unit 106 of the plasma treatment chamber 109. In the surface treatment unit 106, the introduced cathode manufacturing jig 102 can be moved not only in the direction of the magnetron sputtering film forming unit 107 but also in the reverse direction. In addition, as indicated by the symbol 1061 as a symbol, a moving mechanism for moving in a direction perpendicular to the moving direction is also provided.

Next, a processing procedure in the illustrated plasma processing apparatus will be described with reference to FIG. First, the substrate (a cathode manufacturing jig on which a cylindrical cup is mounted in this embodiment) 102 is transferred from the substrate preparation chamber 101 to the surface treatment unit 106 via the gate valve 104. In the surface treatment unit 106, plasma cleaning is performed in an argon (Ar) atmosphere. In this case, argon and hydrogen are introduced into the plasma processing chamber 109 at a flow rate ratio of 9: 1, the pressure is set to 50 mTorr, and 13.56 MHz is applied to the upper plasma excitation electrode provided in the surface processing unit 106. Plasma is excited under the condition that the RF power is 0.2 W / cm ² and the ion irradiation to the cylindrical cup mounted on the cathode manufacturing jig 102 is about 40 eV, and plasma cleaning is performed for 8 seconds. Went.

  Even if plasma excitation is performed only with argon, there is an effect of removing the oxide film, but by introducing hydrogen, the removal effect can be increased by utilizing the reduction effect by hydrogen radicals. In this case, RF power may be simultaneously applied to the lower plasma excitation electrode in order to increase the plasma density and increase the cleaning effect.

Furthermore, with reference to FIG. 4, the nitriding treatment of the cylindrical cup mounted on the cathode manufacturing jig 102 and the LaB ₆ film forming process will be described. The first magnetron sputter film forming unit 107 nitrides the cleaned cylindrical cup surface in a nitrogen-containing atmosphere without performing film formation. For this reason, the two sets of magnetron sputtering sources of the first magnetron sputtering film forming unit 107 are not actually used in this embodiment.

The cathode manufacturing jig 102 on which a cylindrical cup having a nitrided surface is mounted is transferred from the first magnetron sputtering film forming unit 107 to the second magnetron sputtering film forming unit 108. The second magnetron sputter deposition unit 108 includes two sets of magnetron sputter sources (here, LaB ₆ targets) on the top and bottom, but here, only the upper magnetron sputter source (here, LaB ₆ targets). Is used to form a LaB ₆ film.

  The sputtering method of the sputtering source of these magnetron sputtering film forming units 107 and 108 may be a normal magnetron sputtering method in which a fixed magnet is installed on the back surface of the target, but the rotating magnet type magnetron sputtering device shown in FIG. It is preferable to use it. By using a rotating magnet type magnetron sputtering system, the deposition rate can be improved, and the target utilization efficiency is high, so the frequency of target replacement can be reduced, the throughput can be increased, and the running cost can be reduced. it can. For this reason, FIG. 4 shows an example using a rotating magnet type magnetron sputtering apparatus.

When the LaB ₆ film is formed after the nitriding treatment, the LaB ₆ film is less peeled. That is, when the nitriding treatment was not performed, the peeling probability of the LaB ₆ film was 57%, whereas when the nitriding treatment was performed, it was found that the peeling probability of the LaB ₆ film was greatly improved to 25%. . That is, before forming the LaB ₆ film, when the nitriding treatment of the substrate surface, such as tungsten, it was possible to greatly improve the adhesion of the LaB ₆ film.

  Hereinafter, embodiments of the present invention will be listed.

In the embodiment described above, the surface of the cylindrical cup mainly composed of tungsten is nitrided, and then the LaB ₆ film is formed by sputtering, and the cathode body obtained thereby is described. The invention is not limited to the cylindrical cup but can be applied to a substrate having various shapes.

The substrate according to the present invention is not limited to tungsten, but may be molybdenum, silicon, or tungsten or molybdenum containing 4 to 6% by weight of lanthanum oxide, or 4 to 6% La ₂ O by volume ratio. ₃ or tungsten containing molybdenum may be used. Further, the substrate may be resin, glass, or silicon oxide.

The substrate may be tungsten, molybdenum, silicon, or tungsten or molybdenum containing at least one selected from the group consisting of La ₂ O ₃ , ThO ₂ , and Y ₂ O ₃ .

On the other hand, the cathode body according to the present invention is not limited to the LaB ₆ film, but is selected from the group consisting of borides of other rare earth elements, for example, LaB ₄ , YbB ₆ , GaB ₆ , and CeB ₆ . At least one boride may be included.

  The present invention can also be applied to fluorescent tubes including these cathode bodies.

DESCRIPTION OF SYMBOLS 1 Target 2 Columnar rotating shaft 3 Rotating magnet group 4 Fixed outer periphery magnet 5 Outer periphery paramagnetic body 6 Backing plate 7 Housing 8 Refrigerant passage 9 Insulating material 11 Space in processing chamber 12 Feeder wire 13 Cover 14 Outer wall 15 Paramagnetic body 16 Plasma shielding member 18 Slit 19 Cathode body manufacturing jig 30 Cylindrical cup 301 Cylindrical electrode part 302 Lead part 321 Receiving part 322 Gutter part 323 Inclined part 341 Thick LaB ₆ film 342 Thin LaB ₆ film 343 Bottom LaB ₆ film

Claims (11)

A method for producing a LaB ₆ film, comprising: nitriding the surface of the substrate; and subsequently forming a LaB ₆ film on the nitrided surface of the substrate by sputtering in the same processing apparatus. The method for producing a LaB ₆ film according to claim 1, wherein the substrate is tungsten, molybdenum, silicon, or tungsten or molybdenum containing 4 to 6% by weight of lanthanum oxide. The method for producing a LaB ₆ film according to claim 1, wherein the base is resin, glass, or silicon oxide.   A substrate, a layer containing a nitride of the component of the substrate, and a rare earth element boride film formed by sputtering on a surface of the nitride-containing layer. A cathode body. 5. The substrate according to claim 4, wherein the substrate is tungsten, molybdenum, silicon, or tungsten or molybdenum containing at least one selected from the group consisting of La ₂ O ₃ , ThO ₂ , and Y ₂ O _3. Cathode body.   The cathode body according to claim 4, wherein the substrate is resin, glass, or silicon oxide. 7. The cathode body according to claim 4, wherein the rare earth element boride includes at least one boride selected from the group consisting of LaB ₄ , LaB ₆ , YbB ₆ , GaB ₆ , and CeB _6. . According to claim 7, borides of at least one of the rare earth element is selected, a cathode body characterized by a LaB _6. 9. The cathode body according to claim 8, wherein the substrate is tungsten or molybdenum containing 4 to 6% La ₂ O ₃ by volume.   A fluorescent tube using the cathode body according to any one of claims 4 to 9 as a cathode. 4. The nitriding step includes a step of generating a nitrogen gas containing plasma to generate active nitrogen and irradiating at least a part of the surface of the substrate with the active nitrogen. one LaB ₆ film manufacturing method according to the.

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