JP6280355B2 - Manufacturing method of magnetic disk substrate and carrier for polishing treatment - Google Patents

Description

  The present invention relates to a method for manufacturing a magnetic disk substrate and a polishing carrier used for polishing the substrate.

  Conventionally, a glass substrate has been suitably used for a magnetic disk used as one of information recording media. Today, in response to a request for an increase in storage capacity in a hard disk drive device, the density of magnetic recording has been increased. Along with this, the magnetic recording information area is miniaturized by extremely shortening the flying distance from the magnetic recording surface of the magnetic head. It is preferable that the size and shape of the glass substrate used for such a magnetic disk be manufactured with high accuracy as intended.

The surface of the glass substrate is ground and polished in order to accurately produce the size and shape of the glass substrate. In grinding and polishing of a glass substrate, a plate-like grinding or polishing carrier for holding a glass substrate to be ground or polished by being sandwiched between two surface plates during grinding or polishing is used. The carrier is provided with a holding hole for holding the glass substrate.
Conventionally, a fiber reinforced resin obtained by reinforcing a resin with glass fiber has been widely used as the carrier from the viewpoint of mechanical strength and cost. In particular, a carrier having a configuration in which a plurality of layers in which glass fiber is impregnated with an epoxy resin is laminated is preferably used. However, in this carrier, when the glass substrate is ground or polished, a defect, for example, a concave scratch may occur on the end surface (outer peripheral end surface) of the glass substrate. The depth of the scratch is deeper and longer than other scratches formed on the end face. In some cases, abrasive grains in the slurry adhere to the concave portions of the scratches, and a glass chip generated by the scratches adheres to the end surface to become a dust generation source. In particular, the abrasive grains in the polishing slurry used in the final polishing are sandwiched between the end face and the carrier, and are attached as fine particles in the concave wound and further fixed. The fine particles attached in this way may be detached from the end face of the glass substrate during sputtering performed when forming the magnetic layer on the glass substrate and get on the main surface to create a defect in the magnetic layer.

Under such circumstances, there is known a polishing carrier that does not damage the side end face of the object to be polished (Patent Document 1).
Further, there is known a polishing machine carrier that prevents scratches and wear on the outer peripheral end surface of a workpiece when a thin plate workpiece is held and polished by a polishing machine carrier (Patent Document 2).
The above-mentioned polishing carrier that does not damage the side end face of the object to be polished has a holding hole in which the object to be polished is loaded, and the average surface roughness Rac of the inner wall surface of this holding hole is the side of the object to be polished. The inner wall surface of the holding hole is mirror-finished so as to satisfy the relationship of Rac <3Ras with respect to the average surface roughness Ras of the end surface.
On the other hand, in the above-mentioned carrier for a polishing machine that prevents scratches and wear on the outer peripheral end surface of a workpiece such as a glass substrate, the inner peripheral end surface of the work holding hole has a curved concave portion that is curved and depressed along the thickness direction. Is formed.

JP 2008-006526 A JP 2000-301451 A

When the glass substrate was polished using the above-described polishing carrier, the scratches on the outer peripheral end surface of the glass substrate were suppressed to some extent, but the concave scratches still occurred on the outer peripheral end surface. And it cannot fully suppress that the abrasive grains in the polishing slurry adhere to the recessed part of the scratch, and the glass chip generated by the scratch adheres to the outer peripheral end surface of the glass substrate and becomes a dust generation source. It was. In particular, during polishing, in the outer peripheral end surface of the glass substrate, in the portion close to the main surface of the glass substrate located on the upper surface plate side, that is, in the vicinity of the connecting portion between the side wall surface and the chamfered surface orthogonal to the main surface of the glass substrate It was not possible to sufficiently suppress the occurrence of relatively deep scratches.
Moreover, when the glass substrate was polished using the above-described carrier for a polishing machine in which a curved concave portion was formed on the inner peripheral end surface, the concave scratches on the outer peripheral end surface were not reduced. In particular, during polishing, in the outer peripheral end surface of the glass substrate, in the portion close to the main surface of the glass substrate located on the upper surface plate side, that is, in the vicinity of the connecting portion between the side wall surface and the chamfered surface orthogonal to the main surface of the glass substrate Caused a relatively deep wound.

  Therefore, the present invention suppresses the occurrence of scratches on the end surface of the substrate, and further suppresses the formation of defects due to adhesion of fine particles or the like to the main surface of the substrate. An object is to provide a manufacturing method.

In order to solve the above-described conventional problems, the inventor of the present application has intensively studied the carrier and the glass substrate. As a result, the edge portion, which is the boundary between the inner peripheral wall surface of the carrier holding hole and the surface of the carrier, is ground or During polishing, the outer peripheral end surface of the glass substrate is brought into contact with the side wall surface of the outer peripheral end surface of the glass substrate. Specifically, the side wall surface orthogonal to the main surface of the glass substrate is connected to the chamfered surface located on the upper surface plate side. In the vicinity of the part, many of the above scratches occurred. From this fact, it was found that the edge portion of the holding hole of the carrier contacts the side wall surface of the glass substrate during the polishing process of the glass substrate, and the edge portion is damaged by applying a force concentrated on the side wall surface. In addition, when the carrier is composed of a plate material in which a glass fiber is impregnated with a resin material, the main surface of the carrier is rubbed during grinding or polishing of the glass substrate even though the thickness of the carrier is smaller than that of the glass substrate, Hard glass fibers are likely to be exposed on the surface compared to the resin. Further, since the inner peripheral wall surface of the carrier holding hole is rubbed in contact with the glass substrate during the polishing process, more glass fibers are exposed at the edge of the holding hole on the main surface of the carrier, and the edge portion is made of glass. It is easy to make scratches on the outer peripheral edge of the substrate. As described above, the edge portion comes into contact with the side wall surface of the glass substrate and rubs, so that the side wall surface of the outer peripheral end surface of the glass substrate is easily damaged.
Based on the above findings, the present inventors have found the following invention.

That is, one embodiment of the present invention has a holding hole for holding the glass substrate when the glass main surface of the glass substrate is polished by sandwiching a disk-shaped glass substrate between an upper surface plate and a lower surface plate. This is a plate-like carrier for polishing treatment.
The polishing carrier is made of a plate material in which a glass fiber is impregnated with a resin material. A holding hole inner peripheral wall surface defining the holding hole extends from a connection portion of the holding hole inner peripheral wall surface connected to the first carrier main surface of the polishing treatment carrier, and the first carrier main surface of the polishing treatment carrier A first inclined surface inclined with respect to the first carrier main surface, a second carrier main surface orthogonal to the first carrier main surface and opposed to the first carrier main surface, and the first inclined surface. A side wall surface provided between the second carrier main surface and the first inclined surface is provided so as to be connected .
In the cross section of the holding hole cut by a plane that passes through the central axis of the holding hole and is parallel to the thickness direction of the carrier for polishing treatment, the cross-sectional shape of the first inclined surface is relative to the main surface of the first carrier. A linear shape extending with a constant first inclination angle or a convex curve shape with the first inclination angle changed.

The first inclined surface is a surface inclined with respect to the first carrier main surface with the first inclination angle constant.
It is also preferable that the inner peripheral wall surface of the holding hole further includes a convex curved surface with the first inclination angle changed from the end of the first inclined surface to the end of the side wall surface.

  In the cross section of the holding hole, the radius of curvature of the convex curved surface extending from the end of the first inclined surface to the end of the side wall surface is 0.03 times or more the plate thickness of the polishing treatment carrier. It is preferable that it is.

The first inclined surface is a convex curved surface in which the first inclination angle is changed,
In the cross section of the holding hole, it is preferable that the curvature radius of the first inclined surface is 0.03 times or more and 1.0 times or less the plate thickness of the carrier for polishing treatment.

  The first carrier main surface is preferably arranged so as to face the upper surface plate.

Another aspect of the present invention is:
The substrate is sandwiched between an upper surface plate and a lower surface plate with the substrate held in a holding hole provided in a carrier, and the main surface of the substrate and the upper surface plate and the lower surface plate are moved relative to each other. The method for manufacturing a magnetic disk substrate including a polishing process for polishing the main surface of the substrate. In the manufacturing method, the thickness of the carrier is smaller than that of the substrate,
The carrier is composed of a plate material in which a glass fiber is impregnated with a resin material,
A holding hole inner peripheral wall surface defining the holding hole extends from a connection portion of the holding hole inner peripheral wall surface connected to the first carrier main surface of the carrier, and is inclined with respect to the first carrier main surface of the carrier The first inclined surface and the second carrier main surface orthogonal to the first carrier main surface and opposed to the first carrier main surface are connected to the first inclined surface. A sidewall surface provided between the second carrier main surface and the first inclined surface,
In the cross section of the holding hole cut by a plane passing through the central axis of the holding hole and parallel to the plate thickness direction of the carrier, the cross-sectional shape of the first inclined surface is a first shape relative to the first carrier main surface. A linear shape extending with a constant inclination angle or a convex curve shape with the first inclination angle changed,
The carrier is arranged so that the first carrier main surface faces the upper surface plate, and the second carrier main surface facing the first carrier main surface faces the lower surface plate.

The outer peripheral end surface of the substrate includes a substrate side wall surface orthogonal to the main surfaces of the substrates on both sides, and a substrate chamfered surface provided between the substrate side wall surface and the main surfaces of the substrates on both sides. Prepared,
When performing the polishing treatment, the distance Hg from the main surface of the substrate located on the lower surface plate side of the connecting portion between the substrate chamfered surface located on the lower surface plate side and the substrate side wall surface is the first surface. the connecting portion between the first inclined surface and the side wall surface of the carrier, shorter than the distance Hc from the second carrier main surface, it is preferable.

The polishing treatment is, for example, polishing performed by supplying a polishing slurry containing loose abrasive grains between the main surface of the substrate and the upper surface plate and the lower surface plate.
The substrate is, for example, a glass substrate.

According to the manufacturing method and a polishing process for a carrier of the substrate for the above-mentioned magnetic disk, suppressing the occurrence of scratches on the end face of the substrate, further, it is possible to suppress the defects are formed on the main surface of the substrate.

It is a disassembled perspective view of an example of the grinding device (double-side polish apparatus) using the carrier of this embodiment. It is sectional drawing of an example of the grinding apparatus shown in FIG. (A) is sectional drawing of an example of the carrier of this embodiment, (b) is a figure explaining the relationship between the glass substrate under grinding | polishing, and a carrier. (A)-(d) is a figure explaining the other example of the cross section of the holding hole inner peripheral wall surface of the carrier of this embodiment. It is a figure explaining the further another example of the cross section of the holding hole inner peripheral wall face of the carrier of this embodiment.

  The polishing carrier and the method for manufacturing a magnetic disk substrate according to the present invention will be described in detail below. In the present specification, the polishing treatment includes grinding of the glass substrate and polishing of the glass substrate to reduce the roughness of the glass main surface of the glass substrate after grinding. Therefore, the polishing carrier is a carrier that can be used for grinding and polishing a glass substrate.

(Polishing equipment)
A glass substrate polishing apparatus using the polishing carrier of this embodiment will be described with reference to FIGS. FIG. 1 is an exploded perspective view of a polishing apparatus (double-side polishing apparatus). FIG. 2 is a sectional view of the polishing apparatus. Since the grinding apparatus has the same configuration as the polishing apparatus, description of the grinding apparatus is omitted.

  As shown in FIG. 1, the polishing apparatus has a pair of upper and lower surface plates, that is, an upper surface plate 50 and a lower surface plate 60. An annular glass substrate G is sandwiched between the upper surface plate 50 and the lower surface plate 60, and either or both of the upper surface plate 50 and the lower surface plate 60 are moved to operate the glass substrate G and each of the surface plates. By moving the surface plate relative to each other, both main surfaces of the glass substrate G can be polished. A polishing slurry containing abrasive grains is supplied between the glass substrate and the surface plate. Hereinafter, when the upper surface plate 50 and the lower surface plate 60 are collectively described, they are simply referred to as surface plates.

The configuration of the polishing apparatus will be described more specifically with reference to FIGS.
In the polishing apparatus, the polishing pad 10 is attached to the upper surface of the lower surface plate 60 and the lower surface of the upper surface plate 50. In FIG. 1, the polishing pad 10 is shown in a sheet form. For the polishing pad 10, for example, foamed urethane resin or the like can be used.
The carrier 30 has a holding hole 32 for holding the glass substrate G when the disk-shaped glass substrate G is sandwiched between the upper surface plate 50 and the lower surface plate 60 and the main surface of the glass substrate G is polished. Specifically, the carrier 30 includes a tooth portion 31 provided on the outer peripheral portion and meshing with the sun gear 61 and the internal gear 62, and one or a plurality of holding holes 32 for receiving and holding the glass substrate G. . The sun gear 61, the internal gear 62 provided on the outer edge, and the disk-shaped carrier 30 constitute a planetary gear mechanism centered on the central axis CTR as a whole. The disc-shaped carrier 30 meshes with the sun gear 61 on the inner peripheral side and meshes with the internal gear 62 on the outer peripheral side, and accommodates and holds one or more glass substrates G. On the lower surface plate 60, the carrier 30 revolves while rotating as a planetary gear, and the glass substrate G and the lower surface plate 60 are relatively moved. For example, if the sun gear 61 rotates in the counterclockwise direction, the carrier 30 rotates in the clockwise direction, and the internal gear 62 rotates in the counterclockwise direction. As a result, a relative motion occurs between the lower surface plate 60 and the glass substrate G. Similarly, the glass substrate G and the upper surface plate 50 may be relatively moved.

  During the operation of the relative movement, the upper surface plate 50 is pressed against the glass substrate G held by the carrier 30 (that is, in the vertical direction) with a predetermined pressure, whereby the polishing pad is pressed against the glass substrate G. 10 is pressed. Further, as shown in FIG. 2, a polishing slurry is supplied between the glass substrate G and the polishing pad 10 from a supply tank 71 via one or a plurality of pipes 72 by a pump (not shown).

(Career)
3A is a cross-sectional view of an example of the holding hole inner peripheral wall surface 33 of the carrier 30 that defines the holding hole 32, and FIG. 3B illustrates the relationship between the glass substrate G and the carrier 30 being polished. FIG.
The holding hole inner peripheral wall surface 33 of the carrier 30 that defines the holding hole 32 extends from the connection portion 36 of the holding hole inner peripheral wall surface 33 that connects to the first carrier main surface 34 of the carrier 30, and the first carrier main surface of the carrier 30. First inclined surface 37 inclined with respect to 34 is provided. At this time, in the cross section of the holding hole 32 that passes through the central axis of the holding hole 32 (the one-dot chain line in FIG. 3A) and is parallel to the thickness direction of the carrier 30, the cross section of the first inclined surface 37 The shape is a linear shape extending at a constant first inclination angle θ with respect to the first carrier main surface 34.

In the example shown in FIG. 3A, the inner peripheral wall surface 33 of the holding hole has, in addition to the first inclined surface 37, the first carrier main surface 34 and the second carrier main surface facing the first carrier main surface 34. A side wall surface 38 orthogonal to the surface 35 is provided. The first inclined surface 37 is provided between the connection portion 36 of the holding hole inner peripheral wall surface 33 connected to the first carrier main surface 34 and the end of the side wall surface 38. The side wall surface 38 is provided between the first inclined surface 37 and the second carrier main surface 35. The side wall surface 38 connects the end of the first inclined surface 37 and the end of the second carrier main surface 35.
By having such a cross-sectional shape of the inner peripheral wall surface 33 of the holding hole, when the glass substrate G is polished between the polishing pads 10 as shown in FIG. Since the first inclined surface 37 is provided between the side wall surface 38 and the edge portion formed by the first carrier main surface 34 and the side wall surface 38 does not exist. That is, there is no edge portion that contacts the outer peripheral end surface of the glass substrate G, and there is no edge portion that is damaged by applying a concentrated force to the outer peripheral end surface of the glass substrate G. Here, the plate thickness of the carrier 30 is smaller than the plate thickness of the glass substrate G, and the side wall surface 38 of the carrier 30 abuts on the side wall surface 80 orthogonal to the glass main surface of the glass substrate G. Thus, in order for the side wall surface 38 of the carrier 30 and the side wall surface 80 of the glass substrate G to contact, it is preferable that the distance Hg shown in FIG. 3B is shorter than the distance Hc. The distance Hg is from the main surface of the glass substrate G located on the lower surface plate 60 side of the connecting portion 81 between the chamfered surface 82 of the glass substrate G located on the lower surface plate 60 side and the side wall surface 80 of the glass substrate G. Distance. The distance Hc is the distance from the second carrier main surface 35 of the connecting portion 43 between the first inclined surface 37 and the side wall surface 38 of the carrier 30.
At this time, an angle is formed at the connecting portion 43 between the side wall surface 38 and the first inclined surface 37, and this angle is formed between the side wall surface 38 and the first inclined surface 37 at an obtuse angle. Therefore, it is difficult to damage the outer peripheral end surface of the glass substrate G.

  In order to reliably suppress the formation of scratches on the outer peripheral end surface of the glass substrate G, as will be described later, an arcuate curved surface is provided between the side wall surface 38 and the first inclined surface 37, and the side wall surface 38. And the first inclined surface 37 is preferably connected smoothly.

FIGS. 4A to 4D are views for explaining another example of the cross section of the holding hole inner peripheral wall surface 33 of the carrier 30 that defines the holding hole 32.
In addition to the first inclined surface 37 and the slit wall surface 38 shown in FIG. 3A, the holding hole inner peripheral wall surface 33 shown in FIG. 4A has a space between the side wall surface 38 and the second carrier main surface 35. A second inclined surface 39 is provided. The second inclined surface 39 extends from the connection portion 40 of the holding hole inner peripheral wall surface 33 connected to the second carrier main surface 35 and is inclined with respect to the second carrier main surface 35. In the cross section of the holding hole 30, the cross-sectional shape of the second inclined surface 39 is a linear shape that extends with a constant second inclination angle with respect to the second carrier main surface 35. The second inclined surface 39 is provided between the connection portion 40 of the holding hole inner peripheral wall surface 33 connected to the second carrier main surface 35 and the end of the side wall surface 38. The second tilt angle may be the same as or different from the first tilt angle, but is preferably the same. In particular, when the length of the first inclined surface 37 and the length of the second inclined surface 39 are the same, and the first inclined angle and the second inclined angle are the same, the first carrier main surface 34 This is effective in that it is not necessary to distinguish the second carrier main surface 35.

  The sectional shape of the first inclined surface 37 of the inner circumferential wall surface 33 of the holding hole shown in FIG. 4B is different from that of the first inclined surface 37 shown in FIG. 1 is a curved shape in which the inclination angle θ changes. The first inclined surface 37 has a convex shape with respect to the outside of the carrier 30. That is, the inner peripheral wall surface 33 of the holding hole is a side that is orthogonal to the first inclined surface 37 that is convex with respect to the outer side of the carrier 30, the first carrier main surface 34, and the second carrier main surface 35. And a wall surface 38. The first inclined surface 37 smoothly connects the side wall surface 38 and the first carrier main surface 34. Note that the radius of curvature of the convex curved surface of the first inclined surface 37 is not less than 0.03 times and not more than 1.0 times the plate thickness of the carrier 30 so as to suppress scratches on the outer peripheral end surface of the glass substrate G. This is preferable. When the radius of curvature is smaller than 0.03 times the thickness of the carrier 30, the curved surface is bent sharply and the outer peripheral end surface is easily damaged. As long as the above-described distance Hg is shorter than the distance Hc, the first tilt angle θ of the first tilted surface 37 (the tilt angle of the tangent to the first tilted surface 37) is not particularly limited, and the chamfered surface of the glass substrate G 82 may be equal to, larger or smaller than the inclination angle of the glass substrate G with respect to the main surface.

  The sectional shape of the first inclined surface 37 and the second inclined surface 39 of the holding hole inner peripheral wall surface 33 shown in FIG. 4C is the same as that of the holding hole inner peripheral wall surface 33 shown in FIG. In contrast to the first inclined surface 37 and the second inclined surface 39, the cross-sectional shape is an arc shape and the curved shape is convex with respect to the outside of the carrier 30. A side wall surface 38 orthogonal to the first carrier main surface 34 and the second carrier main surface 35 is provided between the first inclined surface 37 and the second inclined surface 39. The first inclined surface 37, the side wall surface 38, and the second inclined surface 39 are smoothly connected to each other. Note that the radius of curvature of the convex curved surfaces of the first inclined surface 37 and the second inclined surface 39 is not less than 0.03 times and not more than 0.5 times the plate thickness of the carrier 30. It is preferable at the point which suppresses the damage | wound of an outer peripheral end surface.

  A first inclination angle θ extending from the end of the first inclined surface 37 to the end of the side wall surface 38 between the first inclined surface 37 and the side wall surface 38 of the inner peripheral wall surface 33 of the holding hole shown in FIG. A curved surface 41 in which is changed is provided. The curved surface 41 is convex with respect to the outside of the carrier 30. The curved surface 41 smoothly connects between the first inclined surface 37 and the side wall surface 38. Therefore, as described above, no corner is formed between the first inclined surface 37 and the side wall surface 38, and scratches are hardly formed on the outer peripheral end surface of the glass substrate G. At this time, in the cross section of the holding hole 32, the radius of curvature of the convex curved surface 41 extending from the end of the first inclined surface 37 to the end of the side wall surface 38 is 0.03 times or more the plate thickness of the carrier 30. It is preferable that the angle is not formed. The upper limit of the radius of curvature is Hg [mm] (see FIG. 3B), which is a distance corresponding to the length of the chamfered surface 82 of the glass substrate G along the thickness direction of the glass substrate G. When the thickness is t [mm], the length is preferably t-Hg [mm]. By the upper limit of the radius of curvature, it is possible to suppress the glass substrate G from being detached from the holding hole 32 and being damaged during polishing.

  4A to 4D, the inner peripheral wall surface 33 of the holding hole has a first inclined surface with respect to the first carrier main surface 34 in the cross section of the holding hole 32. Since it is a linear shape extending with a constant angle θ, or a curved shape that is convex with respect to the outside of the carrier 30 with the first inclination angle θ changed, There is no edge formed by That is, there is no edge portion that contacts the outer peripheral end surface of the glass substrate G, and there is no edge portion that is damaged by applying a concentrated force to the outer peripheral end surface of the glass substrate G.

FIG. 5 is a view for explaining still another example of the cross section of the inner peripheral wall surface 33 of the holding hole of the carrier 30. The holding hole inner peripheral wall surface 33 shown in FIG. 5 extends from the connection portion 36 of the holding hole inner peripheral wall surface 33 connected to the first carrier main surface 34 of the carrier 30, and is inclined with respect to the first carrier main surface 34 of the carrier 30. The first inclined surface 37 is provided. The cross-sectional shape of the first inclined surface 37, that is, the cross-sectional shape when cut by a plane passing through the central axis of the holding hole 32 and parallel to the plate thickness direction of the carrier 30 is the first cross-sectional shape with respect to the first carrier main surface 34. The linear shape extends with a constant inclination angle θ. At this time, unlike the holding hole inner peripheral wall surface 33 provided with the first inclined surface 37 shown in FIG. 3A, the holding hole inner peripheral wall surface 33 shown in FIG. 5 does not have the side wall surface 38 and the holding hole inner peripheral wall surface 33. Is entirely constituted by a first inclined surface 37. In other words, the first inclined surface 37 is connected to the connecting portion 43 of the holding hole inner peripheral wall surface 33 connected to the second carrier main surface 35 from the connecting portion 36 of the holding hole inner peripheral wall surface 33 connected to the first carrier main surface 34. The entire surface of the holding hole inner circumferential wall 33 forms a tapered surface. Even in such a holding hole inner peripheral wall surface 33, there is no edge portion formed by the carrier main surface and the side wall surface as in the prior art. That is, there is no edge portion that contacts the outer peripheral end surface of the glass substrate G, and there is no edge portion that is damaged by applying a concentrated force to the outer peripheral end surface of the glass substrate G. In this case, it is preferable that the first inclination angle θ of the first inclined surface 37 is not less than 45 degrees and not more than 80 degrees. Moreover, it is preferable that it is large with respect to the inclination angle with respect to the main surface of the glass substrate G of the chamfering surface 82 of the glass substrate G. As a result, the glass substrate G being polished is not detached from the holding hole 32 and is not damaged, and stable polishing is possible, and the occurrence of scratches on the outer peripheral end surface of the glass substrate G can be suppressed.
In addition, although the cross-sectional shape of the 1st inclined surface 37 shown in FIG. 5 is a linear shape, a curved shape may be sufficient. When the cross-sectional shape of the first inclined surface 37 shown in FIG. 5 is a curved shape, the maximum value of the first inclination angle θ (the inclination angle of the tangent to the first inclined surface 37) is the chamfered surface of the glass substrate G. It is preferable that 82 is equal to or higher than the inclination angle with respect to the main surface of the glass substrate G in order to stably polish the glass substrate without the glass substrate G being detached from the holding hole 32. Since the first inclination angle θ is maximum at the connection portion 43 between the first inclination surface 37 and the second glass main surface 35, the first inclination angle θ at the connection portion 43 (the first inclination surface 37). Is preferably equal to or larger than the angle of inclination with respect to the main surface of the glass substrate G.

1 and 2, the polishing pad is attached to the upper surface plate 50 or the lower surface plate 60. The upper surface plate 50 or the lower surface plate 60 is provided with fixed abrasive grains, and the glass substrate G and A coolant may be supplied between the upper surface plate 50 or the lower surface plate 60. The carrier 30 can also be used in a grinding device for grinding the glass substrate G in addition to the polishing device.
A polishing apparatus using such a carrier 30 and further a grinding apparatus having substantially the same configuration as the polishing apparatus can be used suitably for manufacturing a glass substrate for a magnetic disk as shown below. In grinding using a glass substrate grinding apparatus, the roughness Ra of the main surface of the glass substrate after grinding is larger than in grinding. In such grinding, the main surface of the glass substrate may be ground by supplying a grinding liquid between each of the upper surface plate and the lower surface plate and the glass substrate. Alternatively, fixed abrasive grains may be provided on each of the upper surface plate and the lower surface plate, and a lubricating liquid may be supplied between the fixed abrasive particles and the glass substrate to grind the main surface of the glass substrate.

(Description of manufacturing method of glass substrate for magnetic disk)
In the manufacturing method of the present embodiment, first, a glass blank that is a material for a plate-shaped magnetic disk glass substrate having a pair of main surfaces is formed. Next, rough grinding of this glass blank is performed. Thereafter, shape processing and end face polishing are performed on the glass blank. Thereafter, fine grinding using fixed abrasive grains is performed on the glass substrate obtained from the glass blank. Thereafter, first polishing, chemical strengthening, and second polishing are performed on the glass substrate. In the present embodiment, the above process is performed. However, the above process is not necessarily performed, and these processes may not be appropriately performed. Hereinafter, each process will be described.

(A) Molding of glass blank In the molding of a glass blank, for example, a press molding method can be used. A circular glass blank can be obtained by the press molding method. Furthermore, it can manufacture using well-known manufacturing methods, such as a downdraw method, a redraw method, and a fusion method. A disk-shaped glass substrate serving as a base of the magnetic disk glass substrate can be obtained by appropriately shaping the plate-shaped glass blank produced by these known production methods.

(B) Rough grinding In rough grinding, specifically, a glass blank was provided on a holding member (carrier) to be mounted on a well-known double-side grinding apparatus of a planetary gear mechanism similar to the apparatus shown in FIGS. The main surfaces on both sides of the glass blank are ground while being held in the holding holes. At this time, the carrier 30 described above can be used. For example, loose abrasive grains are used as the abrasive. In rough grinding, the glass blank is ground so as to approximate the target plate thickness and the flatness of the main surface. In addition, rough grinding is performed according to the dimensional accuracy or surface roughness of the formed glass blank, and may not be performed depending on the case.

(C) Shape processing Next, shape processing is performed. In the shape processing, after forming the glass blank, a circular hole is formed using a known processing method to obtain a disk-shaped glass substrate having a circular hole. Thereafter, the end surface of the glass substrate is chamfered. Accordingly, the end surface of the glass substrate is inclined with respect to the glass main surface between the side wall surface 80 (see FIG. 3B) orthogonal to the main surface and the side wall surface and the glass main surfaces on both sides. A chamfered surface 82 (see FIG. 3B) is formed.

(D) End surface polishing Next, end surface polishing of the glass substrate is performed. The end surface polishing is a process for performing polishing by supplying a polishing liquid containing loose abrasive grains between the polishing brush and the end surface of the glass substrate and moving the polishing brush and the glass substrate relatively, for example. In the end surface polishing, the inner peripheral side end surface and the outer peripheral side end surface of the glass substrate are to be polished, and the inner peripheral side end surface and the outer peripheral side end surface are in a mirror state.

(E) Fine grinding Next, fine grinding is performed on the main surface of the glass substrate. Specifically, grinding is performed on the main surface of the glass substrate using a double-side grinding device having a planetary gear mechanism similar to the polishing device shown in FIGS. Do. In this case, fixed abrasive grains are provided on the surface plate instead of the polishing pad. Specifically, grinding of the main surfaces on both sides of the glass substrate is performed with fixed abrasive grains while holding the glass substrate in the holding holes provided in the carrier 30 described above, which is a holding member of the double-side grinding apparatus. The machining allowance by grinding is, for example, about 10 μm to 200 μm.
In the grinding of this embodiment, the grinding surface containing fixed abrasive grains and the main surface of the glass substrate are brought into contact with each other to grind the main surface of the glass substrate. However, grinding using loose abrasive grains may be performed.

(F) 1st grinding | polishing Next, 1st grinding | polishing is given to the main surface of a glass substrate. Specifically, the main surface on both sides of the glass substrate G is polished while holding the outer peripheral side end face of the glass substrate in the holding hole 32 provided in the carrier 30 of the polishing apparatus shown in FIGS. . The first polishing uses a polishing pad attached to a surface plate using loose abrasive grains. The first polishing removes cracks and distortions remaining on the main surface when, for example, grinding with fixed abrasive grains is performed. In the first polishing, it is possible to reduce the surface roughness of the main surface, for example, the arithmetic average roughness Ra, while preventing the shape of the end portion of the main surface from excessively dropping or protruding.
The free abrasive grains used for the first polishing are not particularly limited. For example, cerium oxide abrasive grains or zirconia abrasive grains are used.
Although the kind in particular of a polishing pad is not restrict | limited, For example, a hard foaming urethane resin polisher is used.

(G) Chemical strengthening The glass substrate can be appropriately chemically strengthened. As the chemical strengthening liquid, for example, a molten liquid obtained by heating potassium nitrate, sodium nitrate, or a mixture thereof can be used. Then, by immersing the glass substrate in the chemical strengthening solution, lithium ions and sodium ions in the glass composition on the surface of the glass substrate are converted into sodium ions and potassium ions having relatively large ion radii in the chemical strengthening solution, respectively. By replacing each, a compressive stress layer is formed in the surface layer portion, and the glass substrate is strengthened.
The timing of performing chemical strengthening can be determined as appropriate, but it is particularly preferable to perform polishing after chemical strengthening because foreign matters fixed on the surface of the glass substrate by chemical strengthening can be removed along with smoothing of the surface. . Moreover, chemical strengthening should just be performed as needed and does not need to be performed.

(H) Second polishing (mirror polishing)
Next, 2nd grinding | polishing is given to the glass substrate after chemical strengthening. The second polishing is intended for mirror polishing of the main surface. Also in the second polishing, a double-side polishing apparatus of a planetary gear mechanism having the same configuration as the double-side polishing apparatus used for the first polishing is used. Specifically, the main surface on both sides of the glass substrate G is polished while holding the outer peripheral side end face of the glass substrate in the holding hole 32 provided in the carrier 30 of the polishing apparatus shown in FIGS. . By doing so, it is possible to reduce the roughness of the main surface while preventing the shape of the end portion of the main surface from excessively dropping or protruding. The second polishing differs from the first polishing in that the type of loose abrasive grains is different and the particle size is reduced, and the hardness of the resin polisher of the polishing pad is softened.

As the free abrasive grains used for the second polishing, for example, fine particles such as colloidal silica are used. By cleaning the polished glass substrate, a glass substrate for a magnetic disk can be obtained.
Although 2nd grinding | polishing is not necessarily essential, it is preferable to implement by the point which can make the level of the surface unevenness | corrugation of the main surface of a glass substrate still better. Thus, the glass substrate subjected to the second polishing becomes a glass substrate for a magnetic disk.

In at least one polishing process of rough grinding, fine grinding, first polishing, and second polishing performed by a grinding apparatus or a polishing apparatus, the first carrier main surface 34 faces the upper surface plate 50, and the second carrier main surface 35. Is preferably arranged to face the lower surface plate 60.
Further, as shown in FIG. 3B, the relationship between the carrier 30 being polished and the glass substrate G is shown along the thickness direction of the glass substrate G on the chamfered surface 82 of the glass substrate G during polishing. The length, that is, the connection portion 81 between the chamfered surface 82 of the glass substrate G positioned on the lower surface plate 60 side and the side wall surface 80 of the glass substrate G from the main surface of the glass substrate G positioned on the lower surface plate 60 side. The distance Hg is shorter than the distance Hc from the second carrier main surface 35 of the connecting portion 43 between the first inclined surface 37 and the side wall surface 38 of the carrier 30 so that the glass substrate G is polished while the holding hole 32 is being polished. It is preferable in that it is prevented from being damaged by being detached (unstable polishing).

  The carrier 30 of the present embodiment has a defect on the main surface of the glass substrate G when polishing is performed by supplying a slurry containing loose abrasive grains between the main surface of the glass substrate G and the upper surface plate 50 and the lower surface plate 60. The effect of making it difficult to scratch the end face of the glass substrate G that captures the fine particles that cause the generation of the defects is great. In particular, since the processing of the main surface of the glass is final in the second polishing, it is preferable to use the carrier 30 of the present embodiment for the second polishing from the viewpoint of making it difficult to damage the end surface of the glass substrate G.

(Example, conventional example)
In order to confirm the effect of this embodiment, various carriers were prepared, and a plurality of glass substrates were polished using the carriers, and scratches (end surface defects) on the outer peripheral end surface of the glass substrate were examined. The inclination angles of the chamfered surfaces 82 on both sides of the side wall surface 80 of the glass substrate G with respect to the main surface of the glass substrate G are all 45 degrees. The glass substrate for magnetic disk to be processed was a glass substrate having a size of 2.5 inches and a thickness of 0.8 mm.
In the manufacturing method of the glass substrate G described above, (e) fine grinding was performed, and then (f) first polishing of the glass main surface was performed under the following conditions using the carriers shown in Tables 1 to 3 below.
Polishing agent: cerium oxide (average particle diameter d50: 1.2 to 1.4 μm)
・ Polishing pad: Soft urethane pad (Suede)
-Stock removal by polishing: 40 μm
Carrier: A plate material in which glass cloth made of glass fiber is impregnated with epoxy resin.

For the evaluation of the end face defect, the presence or absence of a defect (scratch) in the vicinity of the connection portion between the side wall surface 80 and the chamfered surface 82 of the glass substrate G and the depth of the scratch were examined using a laser microscope. In measurement with a laser microscope, the depth of the scratch was examined by measuring the shape at 0.5 μm intervals in the plate thickness direction using a 20 × objective lens. The evaluation when no scratch was found was expressed as “none”, and the case where the scratch was seen but shallow compared to the conventional scratch (specifically, 70% or less of the conventional scratch depth) was “acceptable”. In the case of a flaw having a flaw depth similar to the conventional one (a flaw deeper than 70% of the conventional flaw depth), it is represented as “impossible”.
Moreover, the curvature radius of the cross-sectional shape of the inner peripheral wall surface 33 of the holding hole was obtained from the result of measurement using a commercially available contour shape measuring instrument.
The plate thickness of the carrier 30 was t [mm]. Table 1 below shows the forms of carriers in Examples 1 to 6 and the conventional example, and the evaluation results of end face defects (scratches). In Examples 1-6, the curvature radius of the 1st inclined surface 37 and the 2nd inclined surface 39 was changed. The curvature radii of the first inclined surface 37 and the second inclined surface 39 were the same. The conventional example shown in Table 1 has a form in which there is no first inclined surface 37 and there is an edge portion in which the first carrier main surface and the carrier side wall surface are perpendicular to each other.

  Table 2 below shows the forms of carriers of Examples 7 to 11 and the conventional example, and the evaluation results of end face defects (scratches). The conventional example has the same form as the conventional example shown in Table 1. In Example 7 to Example 11, as shown in FIG. 5, the entire inner peripheral wall surface 33 of the holding hole is configured by the first inclined surface 37, and the first inclination angle θ is changed.

実施例１１の※は、研磨できたガラス基板の端面欠陥は「無し」であったが、一部のガラス基板が保持穴から外れて破損する場合があり、安定した研磨が難しかった、ことを意味する。

In Example 11 *, the end surface defect of the glass substrate that could be polished was “None”, but some glass substrates were detached from the holding holes and could be damaged, and stable polishing was difficult. means.

  Table 3 below shows the forms of carriers of Examples 12 to 21 and the conventional example, and the evaluation results of end face defects (scratches). The conventional example has the same form as the conventional example shown in Table 1. In Example 12 to Example 21, as shown in FIG. 3A, a holding hole inner peripheral wall surface 33 having a first inclined surface 37 and a side wall surface 38 having a linear cross section is used. In Examples 12 to 15, the first inclination angle θ was changed. Since the distance Hc of Examples 12-15 is 0 mm, the form of Examples 12-15 is substantially the same as the form shown in FIG. In Examples 16 to 21, the first inclination angle θ and the distance Hc were changed.

実施例１４，１５，１８，２０の※は、研磨できたガラス基板の端面欠陥は「無し」であったが、一部のガラス基板が保持穴から外れて破損する場合があり、安定した研磨が難しかった、ことを意味する。

In Examples 14, 15, 18 and 20, the end surface defects of the polished glass substrate were “None”, but some glass substrates were detached from the holding holes and could be damaged, and stable polishing. Means it was difficult.

According to the evaluation results in Table 1, in the form of the first inclined surface 37 and the second inclined surface 39 shown in FIG. 4C, the radii of curvature of the first inclined surface 37 and the second inclined surface 39 are The thickness of the carrier 30 is preferably 0.01 times or more and 0.5 times or less of the plate thickness t [mm] from the viewpoint of suppressing end face defects (scratches), and the first inclined surface 37 and the second inclined surface. It can be seen that the radius of curvature of 39 is more preferably 0.03 to 0.5 times the plate thickness t [mm] of the carrier 30.
According to the evaluation results in Table 2, in the form of the first inclined surface 37 shown in FIG. 5, the occurrence of end face defects (scratches) is within an allowable range when the first inclination angle θ is greater than 0 degree and not more than 85 degrees. It was in. In the form of the first inclined surface 37 shown in FIG. 5, the first inclined angle θ is 45 degrees so that the glass substrate can be stably polished without being detached from the holding hole 32 and an end face defect is not generated. It is preferable that it is 80 degrees or less (inclination angle with respect to the main surface of the chamfered surface 82 of the glass substrate G).
According to the evaluation results in Table 3, when the distance Hc is smaller than the distance Hg, including the condition of the distance Hc = 0 [mm], when the first inclination angle θ is not less than 15 degrees and less than 45 degrees, end face defects However, a part of the glass substrate G was damaged, resulting in unstable polishing. This is because a part of the glass substrate G comes off the holding hole 32 and rides on the first inclined surface 37, and an extra force is applied to the glass substrate G. In the form of the first inclined surface 37 in FIG. 3A, when the first inclination angle θ is not less than 45 degrees (inclination angle with respect to the main surface of the chamfered surface 82 of the glass substrate G) and not more than 85 degrees, the distance Hc. Even when the distance Hg is greater than the distance Hg or less than the distance Hg, stable polishing can be performed and the occurrence of end face defects is suppressed. In the condition where the distance Hc is smaller than the distance Hg, it is preferable that the first inclination angle θ is 15 degrees or more and 85 degrees or less from the viewpoint of suppressing the occurrence of end face defects. It is preferable that the inclination angle θ is 15 degrees or more and 80 degrees or less in that no end face defects are generated. Furthermore, it is more preferably 45 degrees or more and 80 degrees or less from the viewpoint of performing stable polishing of the glass substrate G without generating end face defects.

  As mentioned above, although the manufacturing method of the substrate for magnetic disks and the carrier for polishing treatment of the present invention have been described in detail, the present invention is not limited to the above embodiment and examples, and various modifications can be made without departing from the gist of the present invention. Of course, improvements and changes may be made.

DESCRIPTION OF SYMBOLS 10 Polishing pad 30 Carrier 31 Tooth part 32 Holding hole 33 Holding hole inner peripheral wall surface 34 1st carrier main surface 35 2nd carrier main surface 36,40,42,43 Connection part 37 1st inclined surface 38 Side wall surface 39 1st Two inclined surfaces 41 Curved surface 50 Upper surface plate 60 Lower surface plate 61 Sun gear 62 Internal gear 71 Supply tank 72 Pipe 80 Side wall surface 81 Connection portion 82 Chamfered surface

Claims (9)

A plate-shaped polishing carrier having a holding hole for holding the glass substrate when the glass main surface of the glass substrate is polished by sandwiching a disk-shaped glass substrate between an upper surface plate and a lower surface plate. And
The carrier for polishing treatment is composed of a plate material in which a glass fiber is impregnated with a resin material,
A holding hole inner peripheral wall surface defining the holding hole extends from a connection portion of the holding hole inner peripheral wall surface connected to the first carrier main surface of the polishing treatment carrier, and the first carrier main surface of the polishing treatment carrier A first inclined surface inclined with respect to the first carrier main surface, a second carrier main surface orthogonal to the first carrier main surface and opposed to the first carrier main surface, and the first inclined surface. A side wall surface provided between the second carrier main surface and the first inclined surface so as to be connected,
In the cross section of the holding hole cut by a plane that passes through the central axis of the holding hole and is parallel to the plate thickness direction of the polishing treatment carrier, the cross-sectional shape of the first inclined surface is relative to the first carrier main surface. A polishing carrier, characterized in that the carrier has a linear shape extending with a constant first inclination angle or a convex curved shape in which the first inclination angle is changed. The first inclined surface is a surface inclined with respect to the first carrier main surface with the first inclination angle constant.
2. The polishing process according to claim 1, wherein the inner peripheral wall surface of the holding hole further includes a convex curved surface having a first inclination angle changed from an end of the first inclined surface to an end of the side wall surface. Career.   In the cross section of the holding hole, the radius of curvature of the convex curved surface extending from the end of the first inclined surface to the end of the side wall surface is 0.03 times or more the plate thickness of the polishing treatment carrier. The carrier for polishing treatment according to claim 2, wherein The first inclined surface is a convex curved surface in which the first inclination angle is changed,
2. The polishing process according to claim 1, wherein in the cross section of the holding hole, a radius of curvature of the first inclined surface is 0.03 times or more and 1.0 times or less of a plate thickness of the polishing processing carrier. Career.   The polishing carrier according to any one of claims 1 to 4, wherein the first carrier main surface is disposed so as to face the upper surface plate. The substrate is sandwiched between an upper surface plate and a lower surface plate with the substrate held in a holding hole provided in a carrier, and the main surface of the substrate and the upper surface plate and the lower surface plate are moved relative to each other. A method of manufacturing a magnetic disk substrate including a polishing process for polishing the main surface of the substrate,
The thickness of the carrier is smaller than that of the substrate,
The carrier is composed of a plate material in which a glass fiber is impregnated with a resin material,
A holding hole inner peripheral wall surface defining the holding hole extends from a connection portion of the holding hole inner peripheral wall surface connected to the first carrier main surface of the carrier, and is inclined with respect to the first carrier main surface of the carrier The first inclined surface and the second carrier main surface orthogonal to the first carrier main surface and opposed to the first carrier main surface are connected to the first inclined surface. A sidewall surface provided between the second carrier main surface and the first inclined surface,
In the cross section of the holding hole cut by a plane passing through the central axis of the holding hole and parallel to the plate thickness direction of the carrier, the cross-sectional shape of the first inclined surface is a first shape relative to the first carrier main surface. A linear shape extending with a constant inclination angle or a convex curve shape with the first inclination angle changed,
The first carrier main surface faces the upper surface plate, and the carrier is arranged so that the second carrier main surface facing the first carrier main surface faces the lower surface plate. A method for manufacturing a magnetic disk substrate. The outer peripheral end surface of the substrate includes a substrate side wall surface orthogonal to the main surfaces of the substrates on both sides, and a substrate chamfered surface provided between the substrate side wall surface and the main surfaces of the substrates on both sides. Prepared,
When performing the polishing treatment, the distance Hg from the main surface of the substrate located on the lower surface plate side of the connecting portion between the substrate chamfered surface located on the lower surface plate side and the substrate side wall surface is the first surface. the connecting portion between the first inclined surface and the side wall surface of the carrier, the second shorter than the distance Hc from the carrier main surface, a manufacturing method of a substrate according to claim 6.   8. The magnetic disk according to claim 6, wherein the polishing treatment is polishing performed by supplying a polishing slurry containing loose abrasive grains between the main surface of the substrate and the upper surface plate and the lower surface plate. A method for manufacturing a substrate.   The method for manufacturing a magnetic disk substrate according to claim 6, wherein the substrate is a glass substrate.

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