JP2003027220A - Method for depositing composition gradient type vacuum deposition film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that residue in vapor deposition has been generated when a composite vapor deposition material consisting of aluminum and a metallic compound is vacuum-deposited by using a boat for vacuum deposition of a boron nitride material. SOLUTION: The boat for vacuum deposition obtained by coating at least a part mounted with the composite vapor deposition material in the boron nitride material coated with any of tungsten, tantalum and molybdenum in a thickness of >=20 μm is used.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gradient-graded vacuum deposited film in which the composition at the beginning of deposition is mainly aluminum and the composition at the end of deposition is mainly a metal compound. In particular, the present invention relates to a method for manufacturing a heat radiation film provided on the inner wall of a cathode ray tube. 2. Description of the Related Art A cathode ray tube used for a color image display or the like is
It consists of a panel glass which is an image screen, a neck tube for accommodating an electron gun, and a vacuum envelope consisting of a panel glass and a funnel glass connecting the neck tube. The electron beam emitted from the electron gun is passed through the neck of the funnel glass. The deflection yoke provided on the tube side deflects horizontally and vertically to excite and emit light from the color phosphor layer applied to the inner surface of the panel glass, thereby reproducing a required image. In a general structure of a color cathode ray tube, phosphors emitting three colors of red, green and blue are formed on an inner surface of a panel glass. Further, carbon black is formed in the gaps between the phosphors of the respective colors. In general, after a predetermined phosphor is deposited on the inner surface of the panel glass, a metal having good electron permeability, for example, aluminum is deposited to keep the phosphor surface conductive and reflect light toward the back to the front. This has the effect of increasing the amount of light and protecting the phosphor from direct electron impact. That is, an intermediate film made of a resin for smoothing the surface is formed so as to cover the phosphor layer, and a metal vapor-deposited film called a metal back is formed on the intermediate film (Ohm “Phosphor Handbook”). Chapter 3, "Phosphors for color cathode ray tubes"). The intermediate film is finally removed by baking. The metal deposition film is formed, for example, by vacuum-depositing aluminum in a vacuum of about 0.01 Pa. Further, from the viewpoint of luminance, it is formed to a thickness of, for example, about 300 (nm). In a color cathode ray tube, a shadow mask is arranged inside the panel constructed as described above so as to face the phosphor layer, and an electron gun is provided at the neck of the color cathode ray tube. I have. Then, the electron beam emitted from the electron gun is made to pass through a fine hole of the shadow mask, and is caused to collide with a phosphor at a position corresponding to the hole to display an image. The one in which a fine slit is formed instead of a fine hole is called an aperture grill. Since the operation is the same, the operation will be described below with reference to a shadow mask. At this time, the shadow mask is heated by the electron beam that has not passed through the holes of the shadow mask and collides with the shadow mask, thereby emitting infrared radiation, that is, heat radiation from the shadow mask. Further, the heat radiation is reflected by the metal deposition film on the inner surface of the panel to the shadow mask, and the temperature of the shadow mask further increases, the shadow mask thermally expands, and a landing shift of the electron beam in the phosphor layer occurs. Color shift occurs in the projected image. About 20% of the electron beam from the electron gun
Pass through the holes of the shadow mask, but about 80% of the remaining is masked by the shadow mask, so that the shadow mask generates heat. As one of the measures for reducing the color misregistration,
A method of using Invar or Super Invar with a low coefficient of thermal expansion for the shadow mask. Form a heat absorbing film on the metal deposition film formed on the inner surface of the panel and absorb the infrared radiation radiated from the shadow maskIn other words, reduce the amount of reflected infrared light, reduce the infrared light returned to the shadow mask, A method of suppressing thermal expansion of a shadow mask has been used. As the infrared absorbing film, a black metal film made of aluminum (JP-B-62-47341).
No. 9), a carbon film, a film composed of manganese and aluminum or tin (Japanese Patent Publication No. 7-18001), and the like. The black metal film is formed by vacuum-depositing aluminum on the metal-deposited film on the inner surface of the panel, and the carbon film is spray-coated on a metal-deposited film by dissolving carbon in an organic solvent. It is formed by doing. Alternatively, after forming an aluminum film, a hydrocarbon gas is introduced to deposit aluminum, and carbon is coated on the aluminum particles to form an aluminum-carbon layer by vapor deposition on the aluminum layer as if the aluminum particles were carbonized. (Japanese Patent Laid-Open No. 50-128)
457). The film made of manganese and aluminum or tin is formed by vacuum-depositing a mixture or alloy of these. [0006] Invar materials and super invar materials having a low coefficient of thermal expansion are expensive, and the spraying method of the carbon film has a problem that the equipment becomes large-scale. For this reason, it has been studied to form a compositionally graded film that is made of aluminum in the initial stage of vapor deposition (on the phosphor side) and metal having lower light reflectivity than aluminum in the last stage of vapor deposition (on the shadow mask side) in one vacuum deposition. An inventor has already filed an invention of a vapor deposition material having a composite structure in which a metal which is less likely to evaporate than aluminum and has a lower light reflectance than aluminum is disposed on the central axis of the aluminum vapor deposition material (Japanese Patent Application Laid-Open No. 2001-73120). In a single vapor deposition operation by using a composite structure vapor deposition material, the initial stage of vapor deposition is aluminum,
It discloses that a composite composition gradient film of an alloy of aluminum and a metal that hardly evaporates can be obtained at the end of vapor deposition. Also, in order to reduce the absorption of electrons by the film and to reduce the diffusion of the hardly evaporable metal compound into aluminum by baking, a vapor deposition material having a composite structure in which the hardly evaporable metal is replaced with a metal compound is invented. Have already filed an application. The metal compound is an oxide, a nitride, a carbide, a silicide, a nitride oxide, a carbonitride, a carbonate, a silicate, a silicide, a silicide, or a boride of a metal or metalloid element. It is. Metals or metalloids include calcium, aluminum, boron, magnesium, chromium, cobalt, molybdenum, niobium, tantalum, tungsten, lithium, beryllium, nickel, tin, iron,
Lead, silicon, carbon, titanium, vanadium, and manganese. The above-mentioned vapor deposition material of aluminum or a composite structure in which a metal is arranged in an axial region of aluminum is a vapor deposition boat (hereinafter, referred to as a BN boat) of boron nitride ceramic (hereinafter, referred to as a BN material) having a high thermal conductivity. Was used. Since the BN material is an insulator and cannot be energized, titanium (Ti), aluminum (Al), or the like is replaced by aluminum nitride (AlN) or titanium boride (TiB ₂ ) to reduce the electric resistance.
It is added in the form of In general, the composition of a BN boat for vacuum deposition is about 40 wt% of boron (B), about 30 wt% of nitrogen (N), about 10 wt% of Al, and about 20 wt% of Ti.
%. [0009] When a composite vapor deposition material of aluminum and a metal compound is vacuum-deposited using a BN boat, the composite vapor deposition material does not completely evaporate and remains as a vapor deposition residue in the BN boat. Sometimes it was left. For example, when vacuum deposition is performed on a composite deposition material of aluminum and nickel oxide using a BN boat, a deposition residue just like a mechanical pencil lead may be generated. Analysis of this evaporation residue shows that T
i is detected. Ti is detected not only from the surface of the deposition residue but also from the center. Ti must be considered from the BN boat. Therefore, when a board boat is made of a metal having a high melting point such as tungsten (W), molybdenum (Mo), and tantalum (Ta), and the composite vapor deposition material is subjected to vacuum vapor deposition, no vapor deposition residue is generated. Aluminum and a composite composition gradient film of aluminum and a metal compound can be obtained at the end of vapor deposition. From this, it is considered that Ti of the BN boat is a cause of the generation of the evaporation residue. However, in a plate boat made of a high melting point metal such as W, Mo, Ta, etc., even the highest melting point W is about seven times,
In the case of o and Ta, they are broken or bent in about several times and cannot be used. In the process of continuously manufacturing cathode ray tubes, the frequency of changing boats is too high and cannot be used very much. W, Mo, T so that it has strength to reduce the frequency of replacement and does not break or bend
The bulk material a was machined to produce the same size and shape as the BN boat, but the electrical resistance was too small to use with a BN boat specification vapor deposition machine. According to the present invention, a composite vapor deposition material of aluminum and a metal compound is prepared by reducing the frequency of replacing a vapor deposition boat without generating evaporation residues, and in the initial stage of vapor deposition, and in the final stage of vapor deposition, a compositionally graded composite of aluminum and a metal compound. The purpose is to obtain a deposited film. According to the present invention, there is provided a method for producing a compositionally graded vacuum-deposited film, comprising the steps of: preparing an aluminum substrate and at least one metal compound powder dispersed in an axial region of the aluminum substrate; The present invention uses a boat for vacuum evaporation in which at least one of W, Ta, and Mo is coated with a thickness of at least 20 μm on the composite evaporation material mounting surface of the boron nitride material. The grain size of the coating metal is 2 to 20 μm.
m, about 10 μm on average. If the boat for vacuum evaporation is used a plurality of times, the coating metal and aluminum react with each other, or the crystal grain boundaries of the coating metal become clearly visible, and the crystal grains begin to drop. When the crystal grains drop off and the surface of the boron nitride material appears on the surface on which the composite vapor deposition material is mounted, an evaporation residue is generated. In order to extend the life of the vacuum evaporation boat, W, Ta,
Preferably, any one of Mo has a coating thickness of 200 μm or more. The coating of any metal of W, Ta, or Mo on at least the surface of the composite vapor deposition material mounting portion of the BN boat has a film thickness of 20 μm or more by using a spraying technique of spraying a molten metal. A boat for vacuum evaporation can be obtained. Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an external perspective view of a boat for vacuum evaporation according to the present invention. FIG. 2 is an external perspective view of the composite vapor deposition material. FIG. 3 is a schematic diagram of a vacuum evaporation apparatus. As shown in FIG. 1, the boat 1 for vacuum evaporation of the present invention has a thickness of about 3 so as to cover the composite evaporation material mounting portion 3 of the BN boat 2.
Tungsten 4 is coated with a thickness of 00 μm. Tungsten wrapped around at the time of spraying adheres to the side surface of the BN boat, but the thickness is 100 μm or less. The composite vapor deposition material 10 of FIG. 2 is aluminum 11 having an outer diameter of 2 mm, a diameter of a shaft portion 12 of 1.1 mm and a length of 20 mm.
And The metal compound powder of the shaft portion is made of nickel oxide (N
The average particle size of the powder of iO) is 0.3 μm. The weight ratio of aluminum to nickel oxide in the shaft portion is 1: 1;
Nickel oxide accounts for about 12% by weight. The length was 20 mm. The vacuum deposition apparatus 20 shown in FIG. 3 is roughly divided into a vacuum chamber 21, a vacuum exhaust device 22, a power source 2 for deposition.
It consists of three. The vacuum chamber 21 of the vacuum apparatus for manufacturing a cathode ray tube is divided into two, and has a structure in which a front panel glass 25 of the cathode ray tube is placed on a metal bottom portion 24. That is, the front panel 25 as the material to be deposited constitutes a part of the vacuum chamber. The vacuum evaporation boat 1 arranged on the bottom of the vacuum chamber is connected to an evaporation power supply 23 to receive power. Composite vapor deposition material 10 in vacuum vapor deposition boat 1
On the front panel glass 25
Is placed on the metal bottom portion 24 of the vacuum chamber, and a predetermined 3 to 5 × 10 ⁻⁴ torr (about 3 × 1
0 ^-2 Pa) until the reduced pressure. Thereafter, power is supplied from a deposition power supply to the vacuum deposition boat to perform deposition. The power supply to the vapor deposition boat and the time were performed as follows. A current of 100 A was passed for 45 seconds to preheat the vacuum evaporation boat and the composite evaporation material. After preheating,
The current was increased to 230 A and deposition was performed for 35 seconds. Cut off the current, wait for the vacuum evaporation boat to cool down, introduce air into the vacuum chamber, remove the front panel glass,
Observation of the vacuum evaporation boat revealed no residue and all the composite evaporation material had evaporated. The number of vacuum depositions that could be performed using the same vacuum deposition boat without generation of deposition residues was examined. As a result, about 700 times could be used. Observation of the unusable vacuum evaporation boat revealed that the sprayed W having a thickness of about 300 μm was peeled off on the composite evaporation material mounting portion of the BN boat, and the BN material came out on the surface. Since the exfoliated W is a low vapor pressure metal, it did not evaporate and remained in the vacuum evaporation boat. When the deposited film was analyzed, W was not detected from the film. Hereinafter, a second embodiment will be described. Mo is coated on the composite deposition material mounting portion of the BN boat with a thickness of about 200 μm. Mo that had flowed around during the spraying was adhered to the side surface of the BN boat, but the thickness was 80 μm or less. The composite vapor deposition material has an outer diameter of 2 mm and the diameter of the shaft is φ
The length was 1.1 mm and the length was 22 mm. The metal compound powder in the shaft portion is a powder of nickel oxide (NiO) and has an average particle diameter of 0.3 μm. The weight ratio of aluminum to nickel oxide in the shaft portion is 1: 1 and nickel oxide accounts for about 12 wt% of the whole. After a current of 100 A was passed and held for 45 seconds, the current was increased to 240 A and deposition was performed for 35 seconds. Cut off the current and wait for the vacuum evaporation boat to cool down,
The atmosphere was introduced into the vacuum chamber, the front panel glass was removed, and the vacuum evaporation boat was observed, but no residue was found, and all the composite evaporation material had evaporated. The number of vacuum depositions that could be performed using the same vacuum deposition boat without generation of deposition residues was examined. As a result, about 500 times could be used. Hereinafter, a third embodiment will be described. Composite deposition material,
The BN boat is the same as that described in the first embodiment, except that the current flow is changed. In the first embodiment, after the preheating, a current is applied at a stretch until aluminum and nickel oxide are melted. In the present embodiment, the current value at which the aluminum melts after the preheating is maintained for several seconds.
A current of 100 A is applied, held for 45 seconds, preheated, and 180 A
After holding for 5 seconds, the current was increased to 230 A and three stages of vacuum deposition were performed for 32 seconds. FIG. 4 shows the composition distribution in the film thickness direction by Auger analysis of the deposited films of Examples 1 and 3. The composition is arranged by the ratio of aluminum and nickel. Oxygen is naturally detected, but for the sake of clarity, excluding oxygen, the atomic% of aluminum and nickel (a
tm%). FIG. 4 shows that the initial stage of deposition is 300 nm.
And the end of deposition is 0 nm. Although aluminum is 100 atm% in the initial stage of vapor deposition, the composition gradient film is obtained by gradually increasing nickel toward the final stage of vapor deposition. Compared to the first embodiment, the deposited film of the third embodiment is made of aluminum 100 at.
It can be seen that the area of m% increases. This is considered to be because aluminum was evaporated in the second stage of the third stage, and aluminum and nickel oxide were evaporated in the third stage. By changing the holding time in the second stage, the region of 100 atm% of aluminum could be controlled. According to the present invention, the frequency of replacement of a composite vapor deposition material of aluminum and a metal compound is reduced by increasing the life of a vapor deposition boat without generation of evaporation residues, and aluminum is initially deposited and aluminum and metal are vapor deposited at the end of vapor deposition. The compound composite gradient film of the compound was obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an external perspective view of a vacuum evaporation boat according to the present invention. FIG. 2 is an external perspective view of a composite vapor deposition material. FIG. 3 is a schematic diagram of a vacuum vapor deposition device. FIG. 4 is a graph showing a composition distribution of a deposition film in a thickness direction. [Description of Signs] 1 Vacuum evaporation boat, 2 BN boat, 3 Composite deposition material mounting part, 4 tungsten, 5 tungsten, 10
Composite deposition material, 11 aluminum, 12 axis part, 2
0 vacuum evaporation apparatus, 21 vacuum chamber, 22 vacuum exhaust apparatus, 23 power supply for evaporation, 24 bottom part, 25 front panel glass

Claims (1)

Claims: 1. A composite vapor deposition material comprising an aluminum substrate and at least one metal compound powder dispersed in an axial region of the aluminum substrate, wherein the composite vapor deposition material is at least a boron nitride material. A method for producing a compositionally graded vacuum deposition film, comprising performing vacuum deposition using a boat for vacuum deposition in which any one of tungsten, tantalum, and molybdenum is coated on a mounting surface with a thickness of 20 μm or more.