Manufacturing method for ring-shaped object, film forming device, spacer for hard disk drive, and hard disk drive device

Abstract

To provide a manufacturing method for a ring-shaped object that improves productivity of a film formation process while suppressing unevenness in film thickness on the surface of the ring-shaped object.SOLUTION: A manufacturing method for a ring-shaped object (1) includes steps of: placing a ring-shaped substrate (20) on a plate (11); and injecting gas containing a coated material into the central hole of the ring-shaped substrate (20) from above the ring-shaped substrate (20) placed on the plate (11), thereby lifting the ring-shaped substrate (20) from the plate (11) and forming a film (22) on the surface of the ring-shaped substrate (20).SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a ring-shaped object by spray coating onto the entire surface of the ring-shaped object, a coating device, a ring-shaped object, and a hard disk drive device. [Background technology]

[0002] With the recent rise of cloud computing, data centers for cloud computing are using many hard disk drive devices (hereinafter also referred to as HDD devices) to increase storage capacity.

[0003] HDD devices are provided with ring-shaped spacers between magnetic disks to keep them spaced apart. The spacers function to precisely position the magnetic disks at predetermined positions without contacting each other. Conventionally, conductive metal materials, which are inexpensive to manufacture, have been used as spacers. However, when using a glass substrate as the magnetic disk substrate, if the materials of the spacer and the magnetic disk substrate have different linear expansion coefficients, the spacer and the magnetic disk are in contact with each other. As a result, a difference in thermal expansion occurs between the spacer and the magnetic disk as the temperature inside the HDD device changes. This can result in deflection of the magnetic disk, which can deteriorate the flying height of the magnetic head. Deterioration of the flying height of the magnetic head is undesirable from the perspective of reading and writing to the magnetic disk in HDD devices. This problem becomes more significant as recording densities increase.

[0004] For this reason, in recent years, the use of glass spacers (hereinafter referred to as glass spacers) has been considered in order to accommodate the use of glass substrates as magnetic disk substrates (to bring the linear expansion coefficient closer) or to create spacers that are lighter and more rigid than conventional ones. However, because glass is an insulator, static electricity tends to accumulate on the magnetic disk or spacer due to friction between the rapidly rotating magnetic disk and glass spacer and the air. When the magnetic disk or spacer becomes charged, it tends to attract foreign matter and fine particles, and the accumulated static electricity can discharge to the magnetic head, destroying the recording element and reproducing element of the magnetic head, which is undesirable.

[0005] In response to this, a glass spacer is known in which at least the contact surface with the magnetic disk and the inner peripheral surface of the glass spacer are coated with a conductive ceramic film with a thickness of 0.1 to 3 μm (Patent Document 1).This is said to enable static electricity charged to the magnetic disk to be efficiently released, with almost no wear on the contact surface. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 9-44969 Summary of the Invention [Problem to be solved by the invention]

[0007] The glass spacers are manufactured using techniques such as physical vapor deposition (PVD) and chemical vapor deposition (CVD). However, these methods generally have the drawback of being unable to form a film on the area where the spacer-holding member (support member) contacts the spacer. This can result in a portion of the spacer's surface being exposed and uncoated due to the support member's holding. This can lead to glass fragments breaking off and becoming fine particles, resulting in dust formation. To completely eliminate the exposed area, it is possible to remove the spacer from the film-forming apparatus after film formation and perform a second film formation while holding the coated area with a support member. However, performing two film formations can result in uneven film thickness between the area in contact with the support member and other areas. Furthermore, the film-forming process becomes complicated, increasing manufacturing costs.

[0008] The present invention has been made to solve the above-mentioned problems, and aims to provide a technology in a method for manufacturing a ring-shaped object that can improve the productivity of the film-forming process while suppressing unevenness in film thickness on the surface of the ring-shaped object. [Means for solving the problem]

[0009] According to a first aspect of the present invention, there is provided a method for manufacturing a ring-shaped object, the method comprising: placing a ring-shaped substrate on a plate; A method for manufacturing a ring-shaped object is provided, which includes spraying a gas containing a coating material from above the ring-shaped substrate placed on the plate into a central hole of the ring-shaped substrate, thereby floating the ring-shaped substrate from the plate and forming a film on the surface of the ring-shaped substrate.

[0010] In the method for manufacturing a ring-shaped object according to the first aspect of the present invention, the plate may be a heated plate.

[0011] In the method for manufacturing a ring-shaped object according to the first aspect of the present invention, the spraying may be performed multiple times, thereby repeatedly lifting the ring-shaped substrate off the plate and landing it on the plate.

[0012] In the method for producing a ring-shaped object according to the first aspect of the present invention, the gas containing the coating material may be sprayed at a pressure of 0.05 to 1.0 MPa.

[0013] In the method for manufacturing a ring-shaped object according to the first aspect of the present invention, the material of the ring-shaped substrate may include any one of glass, ceramics, metal, and resin.

[0014] In the method for manufacturing a ring-shaped object according to the first aspect of the present invention, the film may be a conductive film or a film containing a conductive metal oxide.

[0015] In the method for manufacturing a ring-shaped object according to the first aspect of the present invention, the ring-shaped object may be a spacer for a hard disk drive.

[0016] According to a second embodiment of the present invention, there is provided a method for manufacturing a ring-shaped object, comprising: a heating treatment in which the ring-shaped substrate is placed on a mounting table and heated; A method for manufacturing a ring-shaped object is provided, which includes a film formation process in which a gas containing a coating material is sprayed onto the ring-shaped substrate to lift the ring-shaped substrate from the mounting table and form a film on the surface of the ring-shaped substrate.

[0017] According to a third aspect of the present invention, there is provided a film forming apparatus, comprising: a plate on which the ring-shaped substrate is placed; a positioning member provided on the plate and configured to position the ring-shaped substrate within a predetermined range on the plate; a nozzle disposed above the plate for spraying a gas containing a coating material into a central hole of the ring-shaped substrate positioned by the member, thereby providing a film forming apparatus.

[0018] In the film deposition apparatus according to the third aspect of the present invention, the positioning member may be at least one partition erected outside the predetermined range on the plate.

[0019] In the film deposition apparatus according to the third aspect of the present invention, the partitions may be plural, and two adjacent partitions among them may be spaced apart so as to surround the predetermined area.

[0020] The film forming apparatus according to the third aspect of the present invention may further comprise a convex portion provided on the plate, and the convex portion may protrude from a central hole of the ring-shaped substrate when the ring-shaped substrate is positioned within the predetermined range.

[0021] In the film forming apparatus according to the third aspect of the present invention, the positioning member may be a convex portion provided on the plate, and the ring-shaped substrate may be positioned within the predetermined range by being placed on the plate so that the convex portion protrudes from a central hole in the ring-shaped substrate.

[0022] The film deposition apparatus according to the third aspect of the present invention may further include a heater for heating the plate.

[0023] According to a fourth aspect of the present invention, there is provided a ring-shaped object, comprising: a ring-shaped substrate having a first main surface and a second main surface facing each other, an outer peripheral end surface, and an inner peripheral end surface; a film formed on the entire surface of the ring-shaped substrate; A ring-shaped object is provided in which the film thickness at the outer peripheral end surface is greater than the film thickness at the inner peripheral end surface.

[0024] In the ring-shaped object according to the fourth aspect of the present invention, the film thickness on the first main surface and the second main surface may be greater than the film thickness on the outer peripheral end surface.

[0025] In the ring-shaped article according to the fourth aspect of the present invention, the material of the ring-shaped substrate may include any one of glass, ceramics, metal, and resin.

[0026] In the ring-shaped object according to the fourth aspect of the present invention, the film may be a conductive film, or may be a film containing a conductive metal oxide.

[0027] The ring-shaped object according to the fourth aspect of the present invention may be a spacer for a hard disk drive.

[0028] According to a fifth aspect of the present invention, there is provided a hard disk drive device including a hard disk drive spacer according to the fourth aspect of the present invention, a magnetic disk, and a magnetic head. [Effects of the Invention]

[0029] According to the present invention, in a method for manufacturing a ring-shaped object, it is possible to improve the productivity of the film formation process while suppressing unevenness in the film thickness on the surface of the ring-shaped object. [Brief explanation of the drawings]

[0030] [Figure 1] (a) is a cross-sectional view of a key part illustrating an example of the structure of an HDD device in which a glass spacer, which is an example of a ring-shaped object of the present invention, is incorporated, and (b) is an oblique view of the glass spacer, which is an example of a ring-shaped object of the present invention. [Figure 2] 1 is a cross-sectional view of a glass spacer, which is an example of a ring-shaped object of the present invention. [Figure 3] 1 is a diagram illustrating an example of a film forming apparatus used in a method for manufacturing a ring-shaped object according to the present invention. [Figure 4] 4A and 4B are cross-sectional views taken along line IV-IV in FIG. 3, where (a) shows a state in which gas containing a coating raw material is not sprayed from a nozzle, and (b) shows a state in which gas containing a coating raw material is sprayed from a nozzle. [Figure 5]4(a) is a view corresponding to FIG. 4(a) showing a modified example of the positioning member, and FIG. 4(b) is a view corresponding to FIG. 4(b) showing a modified example of the positioning member. [Figure 6] 4(b) and 4(c), showing a modified example of a method for floating a ring-shaped glass substrate, which is an example of a ring-shaped substrate, from a plate. DETAILED DESCRIPTION OF THE INVENTION

[0031] First, a glass spacer used in a HDD device will be described, which is an example of a ring-shaped object manufactured by the manufacturing method of the present invention.

[0032] As shown in FIG. 1(a), the HDD device 100 mainly includes a plurality of glass spacers 1, a plurality of magnetic disks 105, a plurality of magnetic heads 106, a spindle 107, and a spindle motor 108. In the HDD device 100, the glass spacers 1 are arranged between adjacent magnetic disks 105 to hold the magnetic disks 105 at predetermined positions with high precision. The magnetic disks 105 and the glass spacers 1 are then inserted into the spindle 107 while being alternately stacked. Note that the HDD device 100 may have a glass spacer 1 that contacts the upper surface of the uppermost magnetic disk 105, or a glass spacer 1 that contacts the lower surface of the lowermost magnetic disk 105.

[0033] As shown in FIG. 1(b), the glass spacer 1 is ring-shaped and includes two opposing main surfaces 2a and 2b, an inner peripheral edge 3, and an outer peripheral edge 4. The main surface 2a is an annular surface having two concentric circles as its outer and inner edges. The main surface 2b is of the same shape as and concentric with the main surface 2a. The inner peripheral edge 3 connects the inner edge of the main surface 2a with the inner edge of the main surface 2b, and the outer peripheral edge 4 connects the outer edge of the main surface 2a with the outer edge of the main surface 2b. Chamfered surfaces may be formed at the connection between the two main surfaces 2a and 2b and the inner peripheral edge 3, and at the connection between the two main surfaces 2a and 2b and the outer peripheral edge 4. In this case, the cross-sectional shape of the chamfered surfaces may be linear or arc-shaped. The two main surfaces 2a and 2b are surfaces that contact the magnetic disk. The inner peripheral end surface 3 is the surface that comes into contact with the spindle 107 of the HDD device 100, and is a wall surface that surrounds a hole with an inner diameter slightly larger than the outer diameter of the spindle 107. The outer peripheral end surface 4 is a surface that does not come into contact with either the magnetic disk 105 or the spindle 107.

[0034] The dimensions of the glass spacer 1 may be changed as appropriate depending on the specifications of the HDD device 100 to be installed, but for a nominal 3.5-inch HDD device, the outer diameter is, for example, 30 to 34 mm, the inner diameter is, for example, 24 to 26 mm, the radial width is, for example, 2 to 5 mm, and the thickness is, for example, 0.5 to 3 mm. Furthermore, if a chamfered surface is formed, the width of the chamfered surface in the radial direction and in the plate thickness direction is, for example, 0.01 to 0.5 mm, respectively.

[0035] As shown in FIG. 2, the glass spacer 1 has a ring-shaped glass substrate 20 and a film 22 that covers the entire surface of the glass substrate 20. In other words, the presence of the film 22 prevents the surface of the glass substrate 20 from being exposed. This makes it difficult for static electricity to accumulate in the glass spacer 1. It also prevents part of the glass substrate 20 from turning into fine particles, generating dust, and adhering to the magnetic disk. It is preferable that the cross-sectional shape of the glass substrate 20 be rectangular, with the radial length longer than the thickness length, because this makes it easier to lift the glass substrate 20 when forming the film 22, which will be described later.

[0036] The thermal expansion coefficient of the glass substrate 20 is preferably approximately equal to that of the glass substrate of the magnetic disk. The material of the glass substrate 20 is not particularly limited, and examples thereof include aluminosilicate glass, soda-lime glass, soda-aluminosilicate glass, aluminoborosilicate glass, boronosilicate glass, and quartz glass. From the viewpoint of crystallinity, either amorphous glass or crystallized glass may be used. Amorphous glass is preferred because it has a relatively high hardness and is easy to improve surface smoothness.

[0037] When the glass substrate 20 is made of amorphous aluminosilicate glass, for example, glass containing 59 to 63 mass% silicon dioxide (SiO), 5 to 16 mass% aluminum oxide (AlO), 2 to 10 mass% lithium oxide (LiO), 2 to 12 mass% sodium oxide (NaO), and 0 to 5 mass% zirconium oxide (ZrO) can be used. This glass is suitable for the glass substrate 20 because of its high rigidity and low thermal expansion coefficient. When the glass substrate 20 is made of soda-lime glass, for example, amorphous glass containing 65 to 75 mass% SiO, 1 to 6 mass% AlO, 2 to 7 mass% CaO, 5 to 17 mass% NaO, and 0 to 5 mass% ZrO can be used. Amorphous aluminosilicate glass and soda-lime glass are suitable for the glass substrate 20 because they are relatively easy to grind and polish, and their surface smoothness can be easily improved.

[0038] The material for the glass substrate 20 may be a ring-shaped glass cut out from a plate glass produced by a float method, a down-draw method, or the like, a glass molded from molten glass by a press method, or a glass sliced ​​from a glass tube produced by a tube drawing method. The glass substrate 20 is obtained by grinding and / or polishing the end faces (inner peripheral end faces and outer peripheral end faces) and main surfaces of the ring-shaped glass thus formed.

[0039] The grinding method for the end face is not particularly limited, and can be performed, for example, using a shaped grindstone containing #80 to #1000 diamond abrasive grains. At this time, a chamfer can be formed at the same time. The end face can also be polished using an abrasive brush with bristles such as nylon. This edge processing can be performed by rotating and contacting the ring-shaped glass with the shaped grindstone or abrasive brush, similar to the edge processing of glass substrates for magnetic disks. Chemical polishing can also be performed using an etching solution containing hydrofluoric acid or hydrosilicofluoric acid.

[0040] The film 22 is a conductive film, and may be a film containing a conductive metal oxide, or a film containing a conductive ceramic. For example, the film 22 may be a film containing any of tin oxide (SnO2), zinc oxide (ZnO), and titanium oxide (TiO2). The film 22 may also be FTO, which is tin oxide doped with fluorine, or AZO, which is zinc oxide doped with aluminum oxide (Al2O3). The degree of conductivity of the film 22 may be determined appropriately as needed, but for example, the surface resistivity at 22°C may be 10 8 [Ω / sq] or less.

[0041] The thickness of the film 22 is preferably 200 nm or less, and more preferably less than 100 nm. A thickness exceeding 200 nm may result in excessive manufacturing costs. Furthermore, a thickness of 100 nm or more may result in significant surface irregularities of the film 22. If the convex portions of the film 22 are too large, upon contact with a magnetic disk, some of the convex portions may detach from the film 22 and become fine particles, potentially causing a magnetic head crash. On the other hand, the thickness of the film 22 is preferably 5 nm or more, and more preferably 10 nm or more, to prevent dust generation and ion elution from the substrate surface. Furthermore, since the outer peripheral end face 4 of the glass spacer 1 is located near the magnetic head after installation in an HDD, dust generation from the outer peripheral end face 4 can easily lead to HDD failure. For this reason, the film thickness of the outer peripheral end face 4 is preferably thicker than the film thickness of the inner peripheral end face 3. Having a thicker film thickness on the outer peripheral end face 4 than the inner peripheral end face 3 helps prevent the above-mentioned problems. The film thickness of each surface may be, for example, the film thickness at the center of each surface.

[0042] (Film forming device 10) Next, as an example of a film deposition apparatus used in the manufacturing method of the present invention, a film deposition apparatus 10 for manufacturing the glass spacer 1 will be described with reference to FIG.

[0043] The film forming apparatus 10 includes a plate 11 (also called a mounting table) on which a ring-shaped glass substrate 20, which is an example of a ring-shaped substrate, is placed, a positioning member 12 provided on the plate 11, a nozzle 13 that sprays gas containing raw materials for the film 22, and a housing (chamber) that accommodates these components. Note that the housing is not shown in FIG. 3.

[0044] (Plate 11) The plate 11 is a metal plate equipped with a heating means such as an electric heater, and can heat the glass substrate 20 placed in contact with the upper surface (also referred to as the mounting surface) of the plate 11. In this specification, the state in which a ring-shaped substrate such as the glass substrate 20 is placed on the upper surface (mounting surface) of the plate 11 (mounting table) also includes a state in which the ring-shaped substrate falls from a floating state (described later) and rests on the upper surface of the plate 11. The heating temperature of the glass substrate 20 may be adjusted appropriately depending on the film to be formed. For example, when forming a conductive tin oxide film 22, the heating temperature is 300 to 600°C. The material of the plate 11 may be any material that can withstand the heating temperature depending on the film to be formed, and may be, for example, metal, glass, ceramics, or the like. At least the area of ​​the surface of the plate 11 that can come into contact with the glass substrate 20 is preferably flat so that it can be efficiently heated when it comes into contact with the glass substrate. The surface roughness of the plate 11 is preferably 5 μm or less in arithmetic mean roughness Ra, and more preferably 3 μm or less. If the Ra exceeds 5 μm, the contact area with the glass substrate decreases, making it difficult to heat quickly, and there is a risk of damaging the surface of the glass substrate when the glass substrate falls from a floating state. The Ra can be measured, for example, with a stylus-type surface roughness measuring instrument. The plate 11 is, for example, rectangular, and the length of each side is greater than the outer diameter of the glass substrate 20. In other words, the plate 11 is sized to fit the entire glass substrate 20.

[0045] (positioning member 12) The positioning member 12 is provided to prevent the glass substrate 20 placed on the upper surface of the plate 11 from being blown out of a predetermined area on the upper surface of the plate 11 by the airflow while the gas containing the raw material of the film 22 is being sprayed from the nozzle 13. It also serves to maintain a high concentration of the gas containing the raw material of the film 22 around the glass substrate 20, thereby reducing film thickness variations across the entire surface of the glass substrate 20 and increasing the rate at which the film 22 is formed. The positioning member 12 is composed of one or more partitions erected outside the predetermined area on the upper surface of the plate 11 so as to surround the predetermined area. The partitions may be made of, for example, metal, glass, ceramics, or a combination of two or more of these materials. The predetermined area on the upper surface of the plate 11 refers to, for example, a circular area having a diameter approximately 3 to 50% larger than the outer diameter of the glass substrate 20. It is more preferable that the predetermined area be a circular area having a diameter approximately 5 to 30% larger than the outer diameter of the glass substrate 20. Therefore, when the glass substrate 20 is placed within a predetermined range on the upper surface of the plate 11, a space is formed at least partially along the outer periphery of the glass substrate 20 between the outer peripheral edge of the glass substrate 20 and the inner surface of the positioning member 12. In other words, the positioning member 12 is positioned a predetermined distance from the outer peripheral edge of the glass substrate 20 (i.e., with a predetermined gap). This gap must be maintained not only when the glass substrate 20 is placed on the upper surface of the plate 11 (assuming the height from the plate 11 is zero), but also when the height from the plate 11 changes, assuming that the glass substrate 20 is lifted. However, it does not necessarily have to be constant in the height direction. This gap allows a film to be formed on the outer peripheral edge of the glass substrate 20. When the positioning member 12 is composed of multiple partitions, adjacent partitions are positioned at a distance from each other. In other words, a gap is formed between adjacent partitions. The size of the gap is not particularly limited as long as the glass substrate 20 can be stably floated, but can be, for example, 1 to 15% of the circumference of an imaginary circle whose center is the center of the circular range (a predetermined range on the upper surface of the plate 11) and whose radius is the distance to both ends of the gap. When the positioning member 12 is composed of multiple partitions, it is preferable to use three or more partitions.This allows the gaps to be distributed evenly around the glass substrate 12, thereby improving levitation stability. The shape of the positioning member 12 (more specifically, the shape of the wall surface of the positioning member 12 facing the glass substrate 20) can be various shapes, such as a circle, an arc, a curve, a straight line, a broken line, or a combination of these, when viewed in a plan view from above the upper surface of the plate 11. The height of the positioning member 12 may be determined appropriately depending on the thickness of the glass substrate 20 and the height to which the glass substrate 20 is to be levitated during film formation, and is, for example, 5 to 50 mm. A member may be further provided to prevent the glass substrate 20 from jumping over the positioning member 12 due to an airflow. For example, a canopy protruding in the direction of arrangement of the glass substrate 20 may be provided on the upper part of the positioning member 12. The canopy shape is preferably such that it does not impede the progress of the gas sprayed from the nozzle 13.

[0046] (Nozzle 13) The nozzle 13 is disposed above the plate 11 within the housing. The nozzle 13 is positioned so that the central axis (the central axis of the jet) of the nozzle 13 fits into the central hole of the glass substrate 20 when the glass substrate 20 is placed within a predetermined range on the upper surface of the plate 11. The central axis of the nozzle 13 is preferably vertical. Furthermore, the central axis of the nozzle 13 preferably passes through the center of the predetermined range. The nozzle 13 jets the raw material for the film 22, together with a gas such as air, toward the central hole of the glass substrate 20 placed within the predetermined range on the upper surface of the plate 11. The raw material for the film 22 is thereby converted into minute droplets (mist) that move or float within the housing. The jet pressure of the nozzle 13 can be, for example, 0.05 to 1.0 MPa. For example, when forming a tin oxide film 22, a liquid obtained by dissolving a tin organic compound such as dibutyltin diacetate or dimethyltin dichloride in a solvent such as ethanol can be used as the raw material for the film 22.

[0047] (Method of manufacturing glass spacer 1) Next, as an example of a method for manufacturing a ring-shaped object of the present invention, a method for manufacturing the glass spacer 1 will be described with reference to Figures 4(a) and 4(b). Note that the housing is also omitted from Figures 4(a) and 4(b).

[0048] First, as shown in Fig. 4(a), the glass substrate 20 is placed within a predetermined range on the upper surface of the plate 11. That is, the glass substrate 20 is placed inside the positioning member 12. Then, the plate 11 is heated with an electric heater, thereby heating the glass substrate 20 placed on the upper surface of the plate 11 to, for example, 400°C.

[0049] Next, as shown in FIG. 4( b), a gas containing the raw material for the film 22 is sprayed from the nozzle 13 toward the central hole in the glass substrate 20. The gas sprayed from the nozzle 13 passes through the central hole in the glass substrate 20 and collides with the upper surface of the plate 11. The gas then flows radially outward along the upper surface of the plate 11 and into the small gap between the lower surface of the glass substrate 20 and the upper surface of the plate 11. This causes the glass substrate 20 to rise from the upper surface of the plate 11. Some of the gas that passes between the lower surface of the glass substrate 20 and the upper surface of the plate 11 flows through the gap in the partition that constitutes the positioning member 12 to the outside of the positioning member 12, while the remaining portion flows upward along the inner surface of the positioning member 12 through the space between the outer peripheral edge of the glass substrate 20 and the inner surface of the positioning member 12. In other words, the gas sprayed from the nozzle 13 flows as shown by the solid arrows in FIG. 4( b). As a result, the glass substrate 20 floats up from the plate 11, and the mist of the raw material of the film 22 floating inside the housing adheres not only to the top surface, inner peripheral edge surface, and outer peripheral edge surface of the glass substrate 20, but also to the bottom surface. That is, the mist of the raw material of the film 22 adheres to the entire surface of the glass substrate 20. At this time, since the glass substrate 20 is heated, when the mist of the raw material of the film 22 adheres to the surface of the glass substrate 20, the solvent evaporates and a chemical reaction of the organic compounds dissolved in the solvent is triggered, and a solid film 22 is formed on the entire surface of the glass substrate 20.

[0050] On the other hand, the temperature of the glass substrate 20 decreases as it floats away from the plate 11 and as the solvent adhering to the glass substrate 20 evaporates. Therefore, a gas containing the raw material of the film 22 is sprayed from the nozzle 13 to float the glass substrate 20 from the plate 11 for a certain period of time, and then the spraying from the nozzle 13 is stopped for a certain period of time. As a result, the floated glass substrate 20 lands on the upper surface of the plate 11, and the glass substrate 20 on which part of the film 22 has been formed is reheated.

[0051] Then, by repeating this spraying and stopping from the nozzle 13 multiple times, in other words, by intermittently spraying from the nozzle 13, it is possible to form a film 22 having the desired physical properties and thickness over the entire surface of the glass substrate 20 while maintaining the temperature of the glass substrate 20 at a predetermined temperature, so that none of the surface of the glass substrate 20 is exposed.

[0052] In order to further stabilize the floating of the glass substrate 20, it is preferable to configure the nozzle 13 so that, for example, a spiral convex portion is provided on the inner wall of the nozzle 13, and the gas containing the raw material of the film 22 is sprayed in a vortex shape.

[0053] According to the method for manufacturing a ring-shaped object described above, a film can be simultaneously formed on the top, bottom, inner peripheral edge, and outer peripheral edge of a ring-shaped substrate by a simple method of spraying a gas containing the film raw material from a nozzle toward the central hole of the ring-shaped substrate. Furthermore, by intermittently spraying from the nozzle, the film thickness can be easily controlled. As a result, ring-shaped objects can be manufactured with very little variation in film thickness on each of the two main surfaces, the inner peripheral edge, and the outer peripheral edge while improving productivity. In particular, since the glass substrate 20 can be brought into contact with the gas containing the film raw material while floating without being supported by a jig or the like, a coating can be formed evenly. Furthermore, impurities are less likely to be introduced into the coating.

[0054] Furthermore, by intermittently spraying from the nozzle, the ring-shaped substrate repeatedly floats up from the plate and lands on the plate. The temperature of the ring-shaped substrate drops as it floats up from the heated plate, and it is reheated by landing on the plate again. In other words, the temperature and heating time of the ring-shaped substrate during film formation can be easily controlled. For example, when forming a conductive tin oxide film, if the substrate temperature is too low, the chemical reaction of the organic compounds used as the film raw material may be insufficient, resulting in insufficient film formation. Therefore, maintaining a high substrate temperature is extremely important. In other words, this method is highly suitable for spray film formation methods that require high-temperature substrate heating.

[0055] Furthermore, the predetermined area on the plate 11 is a circular area having a diameter approximately 3 to 50% larger than the outer diameter of the glass substrate 20, and when the glass substrate 20 is placed within the predetermined area on the upper surface of the plate 11, a space (gap) is formed at least partially along the outer periphery of the glass substrate 20 between the outer peripheral edge surface of the glass substrate 20 and the inner surface of the positioning member 12. Therefore, when the glass substrate 20 is lifted from the plate 11 by the jet from the nozzle 13, the glass substrate 20 vibrates or oscillates finely inside the positioning member 12. This vibration or oscillation has the effect of reducing variations in film thickness on each surface of the glass substrate 20.

[0056] Example 1 A ring-shaped glass substrate 20 was placed on the upper surface of a plate 11 of a film-forming apparatus 10 and heated. The glass substrate 20 had an outer diameter of 32 mm, an inner diameter of 25 mm, and a thickness of 2 mm. The film-forming apparatus 10 had a heatable stainless steel mounting surface (plate) and four identical arc-shaped partitions (30 mm high). The four partitions were arranged so that a circular space with a diameter of 36 mm (corresponding to the above-mentioned "predetermined range") was formed inside, with a 10 mm gap between each of the partitions along the circumference at 90° angles (see Figure 3). In other words, when the center of the circular area inside the four partitions was aligned with the center of the glass substrate 20, a 2 mm gap was formed between the outer periphery of the glass substrate 20 and the partitions. After the glass substrate 20 was heated to 400°C, air containing a film-forming solution was sprayed from a nozzle 13 toward the central hole of the glass substrate 20. The spray pressure of the nozzle 13 was set to 0.3 MPa. During spraying, the glass substrate 20 was lifted from the upper surface of the plate 11. Because the temperature of the glass substrate 20 drops as it lifts from the upper surface of the plate 11, the spraying time for each spray was set to 0.5 seconds. The spraying was stopped after 0.5 seconds, and the glass substrate 20 was allowed to land on the upper surface of the plate 11, thereby reheating the temperature of the glass substrate 20 to 400°C. This operation was repeated 100 times. In other words, the glass substrate 20 was lifted from the upper surface of the plate 11 100 times by spraying from the nozzle 13. A mixed liquid of organic tin and ethanol was used as the film-forming liquid. As a result, a glass spacer 1 was obtained in which a conductive tin oxide film 22 was formed on the entire surface of the glass substrate 20. The cross section of the glass spacer 1 was examined using a scanning electron microscope (SEM), and the film thicknesses of the main surface 2a, the main surface 2b, the inner peripheral edge surface 3, and the outer peripheral edge surface 4 (also referred to as the four main surfaces) were 63 nm, 63 nm, 57 nm, and 61 nm, respectively. In other words, a glass spacer 1 was obtained in which the film thickness variation (maximum film thickness minus minimum film thickness) across the four main surfaces of the glass spacer 1 was extremely small, at 6 nm. The film thicknesses of the inner peripheral edge surface 3 and the outer peripheral edge surface 4 were thinner than those of the main surfaces 2a and 2b, and the film thickness of the outer peripheral edge surface 4 was thicker than that of the inner peripheral edge surface 3. Furthermore, no traces of holding by a holding member were found on the entire surface of the glass spacer 1. Furthermore, the surface resistivity of the film 22 was measured, and it was found to be 10 8[Ω / sq] or less. The film thickness variation rate on the four main surfaces of the glass spacer 1 is defined as (maximum film thickness - minimum film thickness) / (average film thickness) x 100 (%), and in the case of the glass spacer 1, it was approximately 9.8%. A film thickness variation rate of 30% or less is preferable because it results in a smaller film thickness distribution compared to conventional film deposition methods in which films are deposited separately on the front and back surfaces, allowing for lower overall film thickness and lower costs while maintaining conductivity. The film thickness variation rate is more preferable in the following order: 25% or less, 20% or less, 15% or less, and 10% or less.

[0057] Here, we calculate the film thickness variation rate in a conventional film formation method. Specifically, we consider a case in which a film is formed on one main surface, and then the substrate is flipped over and a film is formed on the other main surface. If we assume that a film of the same thickness is formed on the inner and outer peripheral edge surfaces during each film formation, the ratio of film thicknesses on the main surface 2a, main surface 2b, inner peripheral edge surface 3, and outer peripheral edge surface 4 is theoretically 1:1:2:2. In this case, the film thickness variation rate is 66.7%. Therefore, if the film thickness variation rate is 30% or less, it is less than half of the conventional rate, and can be said to be sufficiently small.

[0058] Example 2 Next, a tin oxide film 22 was formed on the surface of a glass substrate 20 in the same manner as in Example 1, except that the number of spraying and heating operations was changed from 100 to 70. The film thicknesses of the four main surfaces were measured, and the film thicknesses of the main surface 2a, the main surface 2b, the inner peripheral edge surface 3, and the outer peripheral edge surface 4 were 47 nm, 48 nm, 40 nm, and 45 nm, respectively. The film thickness variation (maximum film thickness minus minimum film thickness) was 8 nm, and the film thickness variation rate, as defined above, was approximately 17.8%, which was within the preferable range. Furthermore, the film thickness relationships on the four main surfaces, the presence or absence of traces of holding by a holding member, and the surface resistivity of the film 22 were similar to those in Example 1.

[0059] Example 3 Furthermore, a tin oxide film 22 was formed on the surface of a glass substrate 20 in the same manner as in Example 1, except that the number of spraying and heating operations was reduced from 100 to 30. The film thicknesses of the four main surfaces were measured, and the film thicknesses of the main surface 2a, the main surface 2b, the inner peripheral edge surface 3, and the outer peripheral edge surface 4 were 25 nm, 25 nm, 19 nm, and 23 nm, respectively. The film thickness variation (maximum film thickness minus minimum film thickness) was 6 nm, and the film thickness variation rate, as defined above, was approximately 26.8%, which was within the preferable range. The film thickness relationships on the four main surfaces, the presence or absence of traces of holding by a holding member, and the surface resistivity of the film 22 were similar to those in Example 1.

[0060] A HDD device was fabricated by sandwiching multiple glass spacers 1 fabricated by the method of Example 1 between multiple magnetic disks as shown in Figure 1, and a signal recording / reproduction test was performed using a magnetic head. No abnormalities due to static electricity, particles, etc. were observed, and the device operated normally. Similar results were also obtained for the glass spacers 1 fabricated in Examples 2 and 3.

[0061] (Variation) Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible within the scope of the claims. Modifications of the above embodiment will be described below.

[0062] In the above embodiment, the cross-sectional shape of the glass substrate 20 is rectangular, but this is not limited thereto. As long as the glass substrate 20 can be floated by jetting, the cross-sectional shape of the glass substrate 20 may be, for example, circular or elliptical. From the viewpoint of the floating property of the glass substrate 20 by jetting, it is preferable that the radial length of the cross section of the glass substrate 20 is longer than the thickness length.

[0063] In the above embodiment, the glass spacer 1 used in the HDD device is given as an example of the ring-shaped object, but the ring-shaped object is not limited to this and may be, for example, a washer or a packing.

[0064] In the above embodiment, the ring-shaped glass substrate 20 is described as an example of the ring-shaped substrate, but the present invention is not limited thereto. The ring-shaped substrate may be a ring-shaped metal substrate formed of a metal such as aluminum (including aluminum alloys), stainless steel, or titanium (including titanium alloys); a ring-shaped resin substrate formed of a resin such as PDAP (diallyl phthalate), PAI (polyamide imide), PTFE (polytetrafluoroethylene), PPS (polyphenylene sulfide), PI (polyimide), SI (silicone), or PEEK (polyether ether ketone); or a ring-shaped ceramic substrate formed of a ceramic such as alumina, mullite, or zirconia. Alternatively, the material of the ring-shaped substrate may be a composite of two or more materials selected from glass, ceramics, metal, and resin. The film may be, for example, a paint film or another functional film that requires substrate heating.

[0065] The positioning member 12 does not have to be composed of multiple partitions, but may instead be composed of a single annular partition erected to surround a predetermined periphery. In other words, there does not need to be a gap between two adjacent partitions, as in the above embodiment. Furthermore, one or more holes (openings) may be provided in the single annular partition. This opening may be provided in the lower part of the partition so as to include the upper surface of the plate 11, or in the upper part of the partition so that the upper part of the opening is open to the air. In other words, the opening may be formed as a notch in the lower or upper end of the partition. Alternatively, the opening may be provided in the middle of the partition in the height direction so as not to contact the lower or upper ends of the partition. However, if the above gap or opening is too small or not provided at all, there is a risk that the ring-shaped substrate will overflow the partition during gas injection. Therefore, adjustments such as increasing the height of the partition or weakening the injection strength are necessary. If the partition is too tall, it may be difficult to remove the ring-shaped object from inside the partition after film formation. Furthermore, weakening the jet strength may result in a decrease in the film formation rate. Therefore, it is preferable that gaps or openings are formed in the positioning member 12 to allow a portion of the gas jetted from the nozzle to escape to the outside of the positioning member 12. The area of ​​the gaps or openings is preferably 10 to 90%, and more preferably 20 to 70%, of the area of ​​the partition when no gaps or openings are provided (in the case of a single annular partition).

[0066] Furthermore, regardless of the presence or absence of the positioning member 12, a convex portion, for example, having a conical shape, may be provided within a predetermined range on the upper surface of the plate 11. The convex portion may be arranged so that the apex of the convex portion protrudes from a hole in the center of the glass substrate 20 when the glass substrate 20 is positioned within the predetermined range. In this case, by spraying gas containing the film raw material from the nozzle 13 toward the apex of the convex portion, the gas can easily flow into the gap between the lower surface of the glass substrate 20 and the upper surface of the plate 11, thereby improving the floating property of the glass substrate 20 from the plate 11.

[0067] The predetermined range on the plate 11 may be a circular range having the same diameter as the outer diameter of the glass substrate 20, and when the glass substrate 20 is arranged within the predetermined range on the plate 11, no space may be formed between the outer peripheral end face of the glass substrate 20 and the inner surface of the positioning member 12. However, from the viewpoint of reducing variations in film thickness on each surface of the ring-shaped base material, it is preferable that when the glass substrate 20 is arranged within the predetermined range on the plate 11, a space is at least partially formed between the outer peripheral end face of the glass substrate 20 and the inner surface of the positioning member 12.

[0068] The film forming apparatus 10 does not necessarily have to have a housing structure, that is, a housing (chamber) for accommodating the plate 11, the positioning member 12, and the nozzle 13 does not necessarily have to be provided.

[0069] In the above embodiment, a plurality of partitions erected on the upper surface of the plate 11 are given as an example of the positioning member 12, but this is not limiting. As shown in FIGS. 5( a) and 5(b), the positioning member 12 may be, for example, a conical convex portion provided within a predetermined range on the upper surface of the plate 11. As shown in FIG. 5(a), the convex portion may be arranged so that its apex protrudes from a central hole in the glass substrate 20 when the glass substrate 20 is placed within the predetermined range on the upper surface of the plate 11. In this case, as shown in FIG. 5(b), by spraying gas containing film raw materials from the nozzle 13 toward the apex of the convex portion, the gas can easily flow into the gap between the lower surface of the glass substrate 20 and the upper surface of the plate 11, thereby improving the floating property of the glass substrate 20 from the plate 11. Furthermore, even if the glass substrate 20 floating from the plate 11 vibrates or swings while the gas containing the raw material of the film 22 is being sprayed from the nozzle 13, the inner peripheral end face of the glass substrate 20 is caught on the convex portion, so that the glass substrate 20 can be prevented from flying out of the predetermined range.

[0070] In the above embodiment, recesses or grooves may be provided on the plate 11 to the extent that they do not interfere with heating of the glass substrate 20. For example, assuming a circle of any radius centered at the intersection of the central axis of the nozzle 13 and the upper surface of the plate 11, multiple recesses may be arranged in a row in the circumferential direction and / or radial direction of the circle, or grooves extending in the circumferential direction and / or radial direction of the circle may be provided, or a combination of these may be used. By appropriately providing the recesses or grooves, the flow of the sprayed gas can be controlled to improve the floating stability of the glass substrate 20.

[0071] In the above embodiment, when forming the film 22 on the surface of the glass substrate 20, a gas containing the raw material for the film 22 is sprayed from the nozzle 13 provided above the glass substrate 20 toward a central hole in the glass substrate 20, thereby floating the glass substrate 20 from the upper surface of the plate 11. However, the method for floating the glass substrate 20 is not limited to this. For example, as shown in FIG. 6 , the glass substrate 20 may be floated from the upper surface of the plate 11 by spraying a gas containing the raw material for the film 22 from a plurality of nozzles 13 opening on the upper surface of the plate 11 toward at least the lower surface of the glass substrate 20 placed on the upper surface of the plate 11. In this case, it is necessary to provide a plurality of nozzles 13 opening on the upper surface of the plate 11. The spray pressure of the gas containing the raw material for the film 22 may be set to a level sufficient to float the glass substrate 20 from the upper surface of the plate 11, for example, 0.01 to 1.0 MPa. The specifications of the positioning member 12 can be the same as those of the above embodiment. However, a top cover 14 may be provided above the positioning member 12 to prevent the glass substrate 20 from climbing over the positioning member 12 when the gas containing the precursor of the film 22 is sprayed onto the top cover 12, and to improve the uniformity of the film thickness distribution and the film formation rate by increasing the concentration of the gas containing the precursor of the film 22. If the positioning member 12 is configured as a single annular partition without any openings and the film formation space defined by the plate 11, the positioning member 12, and the top cover 14 is sealed, the gas containing the precursor of the film 22 is prevented from being sprayed from the multiple nozzles 13. Therefore, the top cover 14 may be provided with openings to allow the gas containing the precursor of the film 22 to escape from the film formation space. The ratio of the area of ​​the openings in the top cover 14 to the area is preferably 50% or less, more preferably 30% or less, from the viewpoint of the uniformity of the film thickness distribution and the film formation rate.

[0072] In this case, it is preferable to alternately repeat a heating process in which the glass substrate 20 is placed on the upper surface of the plate 11 and heated, and a film formation process in which the glass substrate 20 is floated from the upper surface of the plate 11 and a film 22 is formed over the entire surface of the glass substrate 20. In other words, it is preferable to repeatedly blow a gas containing the raw materials for the film 22 onto the glass substrate 20 multiple times, thereby floating the glass substrate 20 from the upper surface of the plate 11 and landing the glass substrate 20 on the upper surface of the plate 11. While the glass substrate 20 is floating from the upper surface of the plate 11, the film 22 is formed on the surface of the glass substrate 20, but the temperature of the glass substrate 20 drops. If the temperature of the glass substrate 20 drops too much, the chemical reaction of the raw materials for the film 22 may be insufficient, and the film 22 may not be formed. By floating the glass substrate 20 from the upper surface of the plate 11 and then landing it on the upper surface of the plate 11, the temperature of the glass substrate 20, which has dropped due to floating, can be restored.

[0073] In the above embodiment, the plate 11 is provided with a heating means such as an electric heater, and the glass substrate 20 is heated by contact with the plate 11, but this is not limiting. The plate 11 may not be provided with a heating means, and the glass substrate 20 may be heated in a non-contact manner, for example, by infrared rays or the like.

[0074] In the above embodiment, when the injection of the gas containing the raw material is stopped, the injection pressure may be gradually reduced, which can prevent damage to the glass substrate 20 and the film 22 when the glass substrate 20 falls onto the plate 11.

[0075] In the above embodiment, an example is shown in which one glass substrate 20 is placed on the plate 11, but films may be formed simultaneously on a plurality of glass substrates 20 on the plate 11. In this case, the plate 11 may be made large in area, and positioning members 12 and nozzles 13 may be provided according to the number of glass substrates 20 on which films are to be formed.

[0076] The nozzle 13 used in the above embodiment is merely an example, and the nozzle outlet may be processed so that the gas is ejected in a circular pattern along the central axis of the nozzle 13. The nozzle 13 may also have multiple gas outlets. For example, the nozzle 13 may have multiple outlets for ejecting gas horizontally on its side surface, and the nozzle 13 may be installed at a height close to the plate 11 and in the center of a predetermined range, so that the gas is ejected toward the inner peripheral edge of the glass substrate 20 or toward the contact portion of the inner peripheral edge with the plate 11. [Explanation of symbols]

[0077] 1. Glass spacer (an example of a ring-shaped object) 2a,2b Main surface 3 Inner peripheral end face 4 Outer edge 10 Film deposition equipment 11 Plate 12 Positioning member 13 nozzles 20 Glass substrate (an example of a ring-shaped substrate) 22 membrane 100 HDD devices 105 Magnetic Disk 106 Magnetic Head 107 Spindle 108 Spindle motor

Claims

1. A method for manufacturing a ring-shaped object, comprising: placing the ring-shaped substrate on a plate; releasing the ring-shaped substrate above the plate; forming a film on the surface of the ring-shaped substrate spaced above the plate; A method for manufacturing a ring-shaped object, wherein the film is formed by spraying a gas containing a coating material from above the ring-shaped substrate toward a central hole of the ring-shaped substrate.

2. 2. The method for manufacturing a ring-shaped object according to claim 1, wherein the plate is a heated plate.

3. The method for manufacturing a ring-shaped object according to claim 2 , wherein the film is formed by performing the spraying process a plurality of times.

4. 2. The method for manufacturing a ring-shaped object according to claim 1, wherein the gas containing the coating material is sprayed at a pressure of 0.05 to 1.0 MPa.

5. The method for manufacturing a ring-shaped object according to claim 1 , wherein the material of the ring-shaped substrate includes one of glass, ceramics, metal, and resin.

6. 2. The method for manufacturing a ring-shaped object according to claim 1, wherein the film is a conductive film.

7. 7. The method for manufacturing a ring-shaped object according to claim 6, wherein the film contains a conductive metal oxide.

8. A method for manufacturing a ring-shaped object, comprising: a heating treatment in which the ring-shaped substrate is placed on a mounting table and heated; a process of separating the heated ring-shaped substrate above the mounting table; a film forming process for forming a film on the surface of the ring-shaped substrate separated above the mounting table, A method for manufacturing a ring-shaped object, wherein the film forming process is performed by spraying a gas containing a coating material onto the ring-shaped substrate.

9. 9. The method for manufacturing a ring-shaped object according to claim 1, wherein the ring-shaped object is a spacer for a hard disk drive.

10. A film forming apparatus, a plate on which the ring-shaped substrate is placed; a positioning means for positioning the ring-shaped substrate; a nozzle provided above the plate for spraying a gas containing a coating material toward a central hole of the ring-shaped substrate positioned by the positioning means.

11. 11. The film deposition apparatus according to claim 10, wherein the positioning means is at least one partition erected on the plate.

12. 12. The film forming apparatus according to claim 11, wherein the partitions are plural, and two adjacent partitions are spaced apart from each other.

13. 13. The film forming apparatus according to claim 10, further comprising a heater for heating the plate.

14. A spacer for a hard disk drive, comprising: a ring-shaped substrate having a first main surface and a second main surface facing each other, an outer peripheral end surface, and an inner peripheral end surface; a film formed on the first main surface, the second main surface, the outer peripheral end surface, and the inner peripheral end surface of the ring-shaped substrate, the material of the ring-shaped substrate includes glass; the film is a film containing a conductive metal oxide, A spacer for a hard disk drive, wherein the film thickness on the first main surface or the second main surface is thicker than the film thickness on the inner peripheral end face or the outer peripheral end face.

15. 15. The spacer for a hard disk drive according to claim 14, wherein the film thickness on the first main surface or the second main surface is thicker than the film thickness on the inner peripheral end face and the outer peripheral end face.

16. A spacer for a hard disk drive, comprising: a ring-shaped substrate having a first main surface and a second main surface facing each other, an outer peripheral end surface, and an inner peripheral end surface; a film formed on the first main surface, the second main surface, the outer peripheral end surface, and the inner peripheral end surface of the ring-shaped substrate, the material of the ring-shaped substrate includes a metal; the film is a conductive film, A spacer for a hard disk drive, wherein the film thickness on the first main surface or the second main surface is thicker than the film thickness on the inner peripheral end face or the outer peripheral end face.

17. 17. The spacer for a hard disk drive according to claim 16, wherein the film thickness on the first main surface or the second main surface is thicker than the film thickness on the inner peripheral end face and the outer peripheral end face.

18. 18. The spacer for a hard disk drive according to claim 14, wherein the film has a thickness of 5 to 200 nm.

19. A hard disk drive device comprising the hard disk drive spacer according to any one of claims 14 to 17, a magnetic disk, and a magnetic head.

Images