The present invention relates to a hot filament CVD device that forms a coating film on a base material.
Known examples of a coating device for forming a coating film such as a diamond thin film on a surface of a base material include a hot filament CVD device. In such a hot filament CVD device, a mixed gas of hydrocarbons (methane) and hydrogen is preheated by a filament heated to 1000 degrees or more, and the heated gas is introduced into the surface of the substrate to deposit diamond due to thermal decomposition of the hydrocarbons.
Patent Literature 1 discloses a technique in which a workpiece (base material) is disposed inside a filament wound in a cylindrical shape to deposit a uniform diamond film on a surface of the workpiece having a three-dimensional shape. The technique uses a structural member including multiple struts and a beam in the shape of a ring connecting the multiple struts. A single filament is stretched around the struts and the beam of the structural member to form a heating region in a cylindrical shape.
Patent Literature 1: JP H4-6274 A
In the technique described in. Patent Literature 1, the base material (workpiece) is disposed inside the be heating region in a cylindrical shape at the time of coating treatment. In such a structure, it is difficult to dispose multiple base materials in the heating region in a cylindrical shape for the purpose of improving coating treatment efficiency. When the base materials are each a heavy object such as a cemented carbide tool, there is a problem in that a large amount Of time is required for preparatory work for disposing the multiple base materials in the heating region.
It is an object of the present invention to provide a hot filament CVD device capable of easily disposing multiple base materials in a chamber.
The present invention provides a hot filament CVD device that performs coating treatment on multiple base materials. The hot filament CVD device includes: a chamber including a chamber body provided with an opening, and a door attached to the chamber body to seal the opening and allow the opening to be operable; multiple filaments disposed inside the chamber to heat a material gas; multiple base material supports insertable into the chamber through the opening in a predetermined insertion direction, the multiple base material supports supporting the corresponding multiple base materials while allowing the multiple base materials to be disposed at intervals in the insertion direction; and a table having a mounting surface on which the multiple base material supports are allowed to be mounted allowing the multiple base materials to be disposed facing the corresponding multiple filaments, and supporting the multiple base material supports inside the chamber while allowing the multiple base material supports to be disposed adjacent to each other in a chamber width direction intersecting the insertion direction.
Hereinafter, a hot filament CVD device 1 according to an embodiment of the present invention will be described with reference to the drawings.
The hot filament CVD device 1 performs coating treatment on multiple workpieces 5 (base materials). The workpieces 5, for example, are each a drill blade in the present embodiment. As a material of each of the workpieces 5, cemented carbide is typically used. A hot filament CVD method is for forming a thin film using a product of thermal decomposition or a chemical reaction. The hot filament CVD method is a type of chemical vapor deposition (CVD) and uses a decomposition product or a chemical reaction of a material gas due to thermal energy emitted by a filament. The hot filament CVD device 1 can be suitably used for forming a carbon-based thin film, particularly a diamond thin film (polycrystalline diamond thin film). In the present embodiment, the hot filament CVD device 1 forms a diamond thin film on a surface of each of the workpieces 5 by the hot filament CVD method. As a material gas for forming such a diamond thin film, a mixed gas is used in which a carbon compound gas such as a hydrocarbon and a hydrogen gas are mixed. In the present embodiment, a mixed gas composed of 1% methane and 99% hydrogen by volume is used.
The hot filament CVD device 1 includes the chamber 2 having an internal space. The chamber 2 has a chamber body 2S and a door (not illustrated). The chamber body 2S defines the above internal space. The chamber body 2S includes a bottom 20, four (multiple) legs 21, a front flange 22, a right wall 23, a top plate 24, a left wall 25, and a rear wall 26 (
The hot filament CVD device 1 further includes the stage 3, multiple workpiece support blocks 4 (base material supports) for supporting the respective multiple workpieces 5, a filament electrode unit 6 (filament unit), a fixed electrode 71, a movable electrode 72, a left support 73, and a right support 74.
The stage 3 is disposed horizontally inside the chamber 2 and supports the multiple workpiece support blocks 4. The stage 3 has a rectangular shape in plan view; and the legs 21 described above are connected to four corners of a lower surface of the stage 3. When each of the legs 21 is extended and contracted by a stage drive unit 83 described later, the stage 3 moves up and down inside the chamber 2. The stage 3 includes a table 31 in a rectangular shape in top view. The table 31 is formed with a fixing portion 31S in a recessed shape to allow the multiple workpiece support blocks 4 to be disposed without gaps in the left-right direction.
Each of the multiple workpiece support blocks 4 has a rectangular parallelepiped shape (strip shape) elongated in a front-rear direction. Each of the multiple workpiece support blocks 4 can be inserted into the chamber 2 through the opening 211 of the chamber 2 in the insertion direction (refer to arrow DS in
The table 31 described above has a mounting surface that allows the multiple workpiece support blocks 4 to be mounted allowing the multiple workpieces 5 to be disposed facing the corresponding multiple filaments 60. Then, the table 31 supports the multiple workpiece support blocks 4 so that the multiple workpiece support blocks 4 are disposed adjacent to each other in a chamber width direction (left-right direction in
As illustrated in
The fixed electrode 71 and the movable electrode 72 are disposed inside the chamber 2. As illustrated
The left support 73 and the right support 74 support the fixed electrode 71 and the movable electrode 72, respectively. The left support 73 and the right support 74 electrically connect the heating power source 31 and the filament electrode unit 6. Thus, electrical wiring (not illustrated) is provided inside the left support 73 and the right support 74. The left support 73 includes a left outer support 731 exposed to the outside of the chamber 2 and a left inner support 732 located inside the chamber 2 (
As illustrated in
The heating power source 81 allows a predetermined current to flow through the fixed electrode 71 and the movable electrode 72 so that the multiple filaments 60 are heated to about 2000° C. to 2500° C. For the heating power source 81, a high-frequency pulse power source having stable DC characteristics is desirably used.
The electrode drive unit 82 includes a motor and a gear mechanism (not illustrated). The electrode drive unit 82 generates a driving force for moving the movable electrode 72 inside the chamber 2. The electrode drive unit 82 is connected to the right support 74.
The stage drive unit 83 includes a motor and a gear mechanism (not illustrated). The stage drive unit 83 generates a driving force for moving the stage 3 up and down inside the chamber 2. The stage drive unit 83 is connected to the four legs 21.
The operation unit 84 is formed of an operation panel (not illustrated) and accepts various operations for controlling the hot filament CVD device 1.
The display 85 is formed of a liquid crystal panel (not illustrated) and displays information on various movements of the hot filament CVD device 1, for example.
The control unit 80 is configured by a central processing unit (CPU), a read only memory (ROM) for storing a control program, a random access memory (RAM) used as a work area of the CPU, and the like, and operates to functionally include a power source control unit 801, a drive control unit 802, a calculation unit 803, a determination unit 804, a storage unit 805, and an output unit 806, when the CPU executes the control program.
The power source control unit 801 controls the heating power source 81 according to operation information input to the operation unit 84. The power source control unit 801 controls output (kW), heating time, and the like of the heating power source 81.
The drive control unit 802 causes the electrode drive unit 82 according to the operation information input to the operation unit 84 to move the movable electrode 72 to left and right. The drive control unit 802 causes the stage drive unit 83 according to the operation information input to the operation unit 84 to move the stage 3 up and down.
The calculation unit 803 calculates the amount of thermal expansion of the filaments 60 in accordance with heating time of the filaments 60. The calculation unit 803 also calculates the amount of movement setting of the movable electrode 72 based on the amount of thermal expansion.
The determination unit 804 determines disconnection of the filaments 60 based on change in a current value of the heating power source 81. When the determination unit 804 determines that the filament 60 is disconnected, information on the disconnection is displayed on the display 85.
The storage unit 805 stores various parameters, threshold information, and the like for controlling the hot filament CVD device 1. As an example, the storage unit 805 stores parameters for the calculation unit 803 to calculate the amount of thermal expansion of each of the filaments 60.
The output unit 806 outputs various command signals according to the control of the heating power source 81 and the electrode drive unit 82, being performed by the power source control unit 801 and the drive control unit 802.
<Structure of Filament Electrode Unit>
Next, structure of multiple filament cartridges according to the present embodiment will be described in more detail.
In the present embodiment, the filament electrode unit 6 includes a first cartridge 6A, a second cartridge 6B, and a third cartridge 6C (multiple filament cartridges). The first cartridge 6A, the second cartridge 6B, and the third cartridge 6C each have the same structure. Each of the cartridges can be mounted inside the chamber 2 through the opening 2H (
The multiple filaments 60 (
The left frame 61 is a member extending in the front-rear direction and supports left ends of the multiple filaments 60. The left frame 61 includes a left frame front end portion 611, a left frame rear end portion 612, and multiple filament engaging portions 613. The left frame front end portion 611 is disposed at a front end of the left frame 61 and supports a left end portion of the connecting member 63 on a front side. The left frame rear end portion 612 is disposed at a rear end of the left frame 61 and supports a left end portion of the connecting member 63 on a rear side. The multiple filament engaging portions 613 each engage a left end portion of the corresponding one of the filaments 60 (refer to
Similarly, the right frame 62 is a member extending in the front-rear direction and supports right ends of the multiple filaments 60. The right frame 62 includes a right frame front end portion 621, a right frame rear end portion 622, and multiple filament engaging portions (not illustrated, similar to the filament engaging portions 613 described above). The right frame front end portion 621 is disposed at a front end of the right frame 62 and supports a right end portion of the connecting member 63 on the front side. The right frame rear end portion 622 is disposed at a rear end of the right frame 62 and supports a right end portion of the connecting member 63 on the rear side. The multiple filament engaging portions each engage a right end portion of the corresponding one of the filaments 60. When the right frame 62 is supported by the movable electrode 72, the right end portion of each of the filaments 60 and the heating power source 81 are electrically connected to each other through the corresponding one of the filament engaging portions.
The paired connecting members 63 connects respective opposite ends of the left frame 61 in the front-rear direction and corresponding opposite ends of the right frame 62 therein in the left-right direction. With reference to
<Holding Part>
In the present embodiment, the fixed electrode 71 and the movable electrode 72 each include a holding part for holding the filament electrode unit 6. The fixed electrode 71 and the movable electrode 72 are bilaterally symmetrical in shape, so that the fixed electrode 71 will be described below as an example. As illustrated in
Then, with reference to
A case will be described in which the first cartridge 6A, the second cartridge 6B, and the third cartridge 6C are combined overlapping each other in advance as illustrated in
As described above, in the present embodiment, the fixed electrode 71 and the movable electrode 72 each have a shape for guiding the first cartridge 6A, the second cartridge 6B, and the third cartridge 6C that are inserted into the internal space of the chamber 2 through the opening 2H in a mounting direction (arrow DS in
As described above, the coating treatment to the multiple workpieces 5 is prepared such that the filament electrode unit 6 is mounted on the fixed electrode 71 and the movable electrode 72, and the multiple workpiece support blocks 4 supporting the corresponding multiple workpieces 5 are mounted on the table 31. When the door (not illustrated) is closed, the inside of the chamber 2 is evacuated by the vacuum pump and the mixed gas is introduced. When the operator operates the operation unit 84 (
Next, when the power source control unit 801 causes the heating power source 81 to allow a current to flow into the fixed electrode 71 and the movable electrode 72 in response to operator's operation, heating of the multiple filaments 60 is started. Then, each of the filaments 60 thermally expands with the heating . In the present embodiment, the electrode drive unit 82 can move the movable electrode 72 in the left-right direction (extending direction of the filaments 60) as described above. The calculation unit 803 calculates the amount of thermal expansion ΔL (mm) of each of the filaments 60 from Equation 1.
ΔL=α×(T2−T1)×L (Equation 1)
In Equation 1, α is a coefficient of thermal expansion for each material, T1 is room temperature (°C.), T2 is the temperature of the filaments 60 measured with a radiation thermometer, and L (mm) is an original length of each of the filaments 60.
Then, the drive control unit 802 causes the electrode drive unit 82 to move the movable electrode 72 to the right (in the direction of pulling the filaments 60) by the amount of thermal expansion calculated by the calculation unit 803. At this time, in the present embodiment, the movable electrode 72 is moved by the amount of thermal expansion of the filaments 60, so that no extra tension is applied to the filaments 60. As a result, a central portion of each of the filaments 60 is prevented from hanging downward (deforming) due to the thermal expansion of each of the filaments 60. Such movement control of the movable electrode 72 (attitude control of the filaments 60) is mainly performed in an initial stage of heating where the temperature of the filaments 60 rises. Such control may be continued throughout coating treatment time for the workpieces 5.
When each of the filaments 60 reaches a predetermined heating temperature in accordance with input power of the heating power source 81, the filaments 60 be at the material gas in the chamber 2, and then graphite and other non-diamond carbons react with atomic hydrogen and evaporate. Here, the atomic hydrogen reacts with an original hydrocarbon gas (methane) to form carbon-hydrogen species with high reactivity. When this species decomposes, hydrogen is released, pure carbon or diamond is formed, and a diamond film is formed on each of the workpieces 5.
As described above, in the present embodiment, the central portion of each of the filaments 60 is prevented from hanging downward during the coating treatment, so that a distance between each of the filaments 60 and the corresponding one of the workpieces 5 is prevented from varying in a longitudinal direction (left-right direction) of each of the filaments 60. This prevents fluctuation in deposition speed of each of the workpieces 5 and variation in deposition result (film thickness, uniformity) from occurring depending on a position on the table 31. When multiple filaments 60 are disposed adjacent to each other in the vertical and front-rear directions in the chamber 2 as in the present embodiment, direct measurement of temperature of each of the filaments 60 using a conventional radiation thermometer is likely to cause measurement accuracy to deteriorate. Additionally, each of the filaments 60 has a small diameter. This causes measurement of infrared rays and electromagnetic waves emitted to be difficult, and measuring equipment to be expensive. In contrast, in the present embodiment, the amount of thermal expansion of each of the filaments 60 is calculated in accordance with output power of the heating power source 81, and the movable electrode 72 is moved in accordance with the amount of the thermal expansion. Thus, as compared with a case where temperature of each of the filaments 60 is directly measured, control variation is reduced, an attitude of each of the filaments 60 is stably maintained, and coating quality for each of the workpieces 5 is improved.
As described above, in the present embodiment, the filament cartridges 6A, 6B and 6C supporting the multiple filaments 60 are inserted into the chamber 2 through the opening 2H. At this time, the fixed electrode 71 and the movable electrode 72 guide each of the filament cartridges, so that each of the filament cartridges can be easily inserted into the chamber 2. The fixed electrode 71 and the movable electrode 72 also hold each of the filament cartridges in the chamber 2 so that the multiple filaments 60 face the corresponding multiple workpieces 5. This enables each of the multiple filaments 60 to be easily disposed at a coating treatment position inside the chamber 2. Additionally, when a part of the multiple filaments 60 is broken, the broken filament 60 can be easily removed by replacing the corresponding filament cartridge.
In the present embodiment, multiple filament cartridges can be easily attached inside the chamber 2 and detached from inside the chamber 2. The filaments 60 of each of the multiple filament cartridges are disposed at intervals in the vertical direction, so that a coating treatment space in which each of the workpieces 5 is insertable can be formed between the filaments 60 adjacent to each other in the front-rear direction.
In the present embodiment, even when the multiple filaments 60 are thermally expanded during the coating treatment, hanging down or deformation of the multiple filaments 60 can be prevented by changing a distance between the left frame 61 and the right frame 62 using the electrode drive unit 82. Each of the paired connecting members 63 of each filament cartridge has the telescopic portion 63H, so that the above deformation due to thermal expansion can be prevented while cartridge structure of the multiple filaments 60 is maintained.
In the present embodiment, the multiple workpiece support blocks 4 supporting the corresponding multiple workpieces 5 can be inserted into the chamber 2 through the opening 2H. At this time, the operator can insert the multiple workpiece support blocks 4 in the predetermined insertion direction while sliding the workpiece support blocks 4 on the mounting surface of the table 31. Thus, even when each of the workpieces 5 is a heavy object, the multiple workpieces 5 can be easily disposed at respective coating treatment positions facing the corresponding multiple filaments 60 inside the chamber 2. The multiple workpiece support blocks 4 mounted on the mounting surface are disposed adjacent to each other in the left-right direction (chamber width direction). This enables the multiple workpieces 5 to be densely disposed inside the chamber 2.
In the present embodiment, when leading end portions of the respective multiple workpiece support blocks 4 come into contact with the restriction portion 31T, positions of the multiple workpiece support blocks 4 and also positions of the multiple workpieces 5 supported on the respective workpiece support blocks 4 in the insertion direction are restricted. When the multiple workpiece support blocks 4 are inserted in order, the workpiece support block 4 inserted earlier can guide the adjacent workpiece support block 4 to be inserted later. When all the workpiece support blocks 4 are inserted, positions of the multiple workpiece support blocks 4 and also positions of the multiple workpieces 5 supported on the respective workpiece support blocks 4 in the chamber width direction are restricted. As a result, the position of each of the workpieces 5 is restricted, so that the coating treatment on the workpieces 5 can be stably performed.
According to the present embodiment, the filament holding mechanism is provided, which holds the multiple filaments 60 so that the multiple filaments 60 extend in the first direction parallel to the insertion direction and are disposed apart from each other in the second direction intersecting the first direction, and face the corresponding multiple workpieces 5 in the third direction intersecting the plane including the first direction and the second direction inside the chamber 2. Another filament holding mechanism may be provided, which holds the multiple filaments 60 in the third direction intersecting the plane including the first direction and the second direction while allowing the multiple filaments 60 to face the corresponding multiple workpieces 5, wherein the multiple filaments 60 extend in the first direction intersecting the insertion direction and are disposed apart from each other in the second direction intersecting the first direction inside the chamber 2. According to these configurations, a plane including the multiple filaments 60 is disposed facing the multiple workpieces 5 in the vertical direction (third direction). This enables the coating treatment to be applied to the multiple workpieces 5 in a wide range.
In the present embodiment, when the workpieces 5 are inserted into the corresponding multiple support holes 4H of each of the workpiece support blocks 4, and the workpiece support blocks 4 are held on the table 31 of the stage 3, a coating treatment position of each of the workpieces 5 can be aligned with the corresponding one of the multiple filaments 60.
In the present embodiment, when the stage drive unit 83 moves the stage 3 including the table 31 in the vertical direction, the table 31 can be moved between the coating treatment position at which the multiple workpieces 5 are held at respective positions close to the corresponding multiple filaments 60, and a separation position at which the multiple workpieces 5 are held at respective positions further apart downward from the corresponding multiple filaments 60 than the coating treatment position.
Although the hot filament CVD device 1 according to an embodiment of the present invention has been described above, the present invention is not limited to the embodiment. As the hot filament CVD device according to the present invention, the following modified. embodiments are applicable.
(1) Although the above embodiment is described in which the first cartridge 6A, the second cartridge 6B, and the third cartridge 6C are inserted into the chamber 2 in the front-rear direction (arrow DS in
(2) Although the above embodiment is described in which the fixed electrode 71 and the movable electrode 72 each include the holding part of the present invention, an electrode for applying voltage to the multiple filaments 60 may have another structure. In this case, paired holding parts each having an engaging recess 71H as in the above embodiment may be provided in the chamber 2, and voltage may be applied to each of the filaments 60 through a path different from the holding parts.
(3) Although the above embodiment is described in which the electrode drive unit 82 moves the movable electrode 72 in accordance with thermal expansion of the filaments 60, the present invention is not limited to this. The hot filament CVD device 1 may include only the cartridge structure of the filament electrode unit 6 without including a mechanism for moving the electrode (holding part). The workpiece support block 4 may be formed of one block placed on the table 31 without being divided into multiple blocks.
(4) Although the above embodiment is described in which when the movable electrode 72 is moved in accordance with thermal expansion of the multiple filaments 60, the amount of movement of the movable electrode 72 is calculated using Equation 1, the present invention is not limited to this. The amount of thermal expansion of each of the filaments 60 in accordance with output of the heating power source 81 and heating time (voltage application time) of each of the filaments 60 may be preliminarily measured in an experiment (experimental data) and stored in the storage unit 805. In this case, the drive control unit 802 (
The present invention provides a hot filament CVD device that performs coating treatment on multiple base materials. The hot filament CVD device includes: a chamber including a chamber body provided with an opening, and a door attached to the chamber body to seal the opening and allow the opening to be openable; multiple filaments disposed inside the chamber to heat a material gas; multiple base material supports insertable into the chamber through the opening in a predetermined insertion direction, the multiple base material supports supporting the corresponding multiple base materials while allowing the multiple base materials to be disposed at intervals in the insertion direction; and a table having a mounting surface on which the multiple base material supports are allowed to be mounted allowing the multiple base materials to be disposed facing the corresponding multiple filaments, and supporting the multiple base material supports inside the chamber while allowing the multiple base material supports to be disposed adjacent to each other in a chamber width direction intersecting the insertion direction.
According to the present configuration, the multiple base material supports supporting the corresponding multiple base materials can be inserted into the chamber through the opening. At this time, the operator can insert the multiple base material supports in the predetermined insertion direction while sliding the base material supports on the mounting surface of the table. Thus, the multiple base materials can be easily disposed at respective coating treatment positions facing the corresponding multiple filaments inside the chamber. The multiple base material supports mounted on the mounting surface are disposed adjacent to each other in the chamber width direction. This enables the multiple base materials to be densely disposed inside the chamber.
The above configuration may be configured such that the table includes a body part having the mounting surface, a standing wall that comes into contact with a leading end in the insertion direction of each of the multiple base material supports mounted on the mounting surface to restrict the multiple base material supports in the insertion direction, and paired side walls that are each brought into contact with a side surface of a corresponding one of paired base material supports located at respective opposite ends of the multiple base material supports mounted on the mounting surface in the chamber width direction, a distance between the paired side walls in the chamber width direction being set to bring the multiple base material supports into contact with each other to restrict the multiple base material supports in the chamber width direction.
According to the present configuration, when the leading ends of the respective multiple base material supports come into contact with the standing wall, the multiple base material supports and also the multiple base materials supported on each of the base material supports are restricted in the insertion direction. When the multiple base material supports are inserted in order, the base material support inserted earlier can guide the adjacent base material support to be inserted later. When all the base material supports are inserted., the multiple base material supports and also the multiple base materials supported on each of the base material supports are restricted in the chamber width direction.
The above configuration may further include a filament holding mechanism that holds the multiple filaments so that the multiple filaments extend in the first direction that is any one of the insertion direction and the chamber width direction and are disposed apart from each other in the second direction that is another of the insertion direction and the chamber width direction, and face the corresponding multiple base materials in a third direction intersecting a plane including the first direction and the second direction inside the chamber.
According to the present configuration, a plane including the multiple filaments is disposed facing the multiple base materials in the third direction. This enables the coating treatment to be applied to the multiple base materials in a wide range.
The above configuration is desirably configured such that the multiple base material supports are each provided with multiple base material holding parts in the insertion direction that hold the corresponding multiple base materials, and the multiple base material holding parts in the respective base material supports are located at respective positions at which the multiple base materials are disposed between the corresponding multiple filaments when viewed from the third direction.
According to the present configuration, when the base materials are held by the respective multiple base material holding parts of each of the base material supports, and the base material supports are supported by the table, the multiple base materials can be easily aligned with the corresponding multiple filaments.
The above configuration desirably further includes a moving mechanism that moves the table in the third direction to move the multiple base materials between a coating treatment position at which the multiple base materials are held close to the corresponding multiple filaments and a separation position at which the multiple base materials are held further apart from the multiple filaments than the coating treatment position in the third direction.
According to the present configuration, when the moving mechanism moves the table in the third direction, the table can be moved between the coating treatment position and the separation position.
Number | Date | Country | Kind |
---|---|---|---|
2018-168448 | Sep 2018 | JP | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/JP2019/032303 | 8/19/2019 | WO | 00 |