JP2015064920A - Manufacturing method of glass substrate for magnetic disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain quality of a glass substrate while satisfying a surface roughness required in a polishing process.SOLUTION: In a manufacturing method of a glass substrate for a magnetic disk, a polishing device includes a carrier for holding the glass substrate and a surface table on which a polishing pad is stuck while facing a principal surface of the glass substrate held by the carrier. The manufacturing method of the glass substrate for the magnetic disk includes a polishing process in which a polishing liquid containing abrasive grains is supplied between the principal surface of the glass substrate held by the carrier and the polishing pad, and the glass substrate and the polishing pad are relatively moved so as to polish the principal surface of the glass substrate. After completion of the polishing, the polishing pad is removed from the principal surface of the glass substrate while relatively moving the carrier and the surface table on a plane parallel to the principal surface of the glass substrate held by the carrier.

Description

  The present invention relates to a method for manufacturing a glass substrate for a magnetic disk.

  Conventionally, a glass substrate is 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 main surface of the glass substrate is polished in order to manufacture the glass substrate with high accuracy in size and shape. In the polishing process of the glass substrate, a plate-shaped polishing carrier for holding the glass substrate that is sandwiched between two surface plates to which a polishing pad is attached and is polished during polishing is used. The carrier is provided with a holding hole for holding the glass substrate.
Conventionally, after the contact between the main surface of the glass substrate held in the holding hole of the carrier and the surface plate is started, the glass substrate is fixed on the surface parallel to the main surface of the glass substrate held by the carrier. The main surface of the glass substrate is polished by relatively moving the board. At this time, after applying a load to the main surface of the glass substrate with the surface plate, the polishing can be efficiently performed by pressing the polishing pad against the main surface of the glass substrate.

JP 2002-150548 A

  However, in the conventional polishing process, after the polishing of the main surface of the glass substrate is completed, the surface is parallel to the main surface of the glass substrate held by the carrier before the polishing pad is pulled away from the main surface of the glass substrate. Since the relative motion between the glass substrate and the surface plate is stopped, the load from the surface plate is not applied to the main surface of the glass substrate until the main surface of the glass substrate moves away from the polishing pad after the relative motion stops. The pressing force is applied only in the vertical direction. Therefore, when there is foreign matter between the main surface of the glass substrate and the surface plate, the pressing force on the main surface of the glass substrate is locally only in the vertical direction through foreign matter or aggregates of abrasive grains. Therefore, deep cracks and pits are generated in the vertical direction from the main surface of the glass substrate.

  Conventionally, since the surface roughness required in the polishing process is large, the influence (for example, the level of defects) on the quality of the glass substrate due to the cracks and pits is small. However, in recent years, since the surface roughness required in the polishing process has been reduced, the influence on the quality of the glass substrate due to the cracks and pits cannot be ignored. As a result, the quality of the glass substrate cannot be maintained while satisfying the surface roughness required in the polishing process.

  Then, an object of this invention is to provide the manufacturing method of the glass substrate for magnetic discs which can maintain the quality of a glass substrate, satisfy | filling the surface roughness requested | required in grinding | polishing processing.

  According to the first aspect of the present invention, a polishing liquid containing abrasive grains is supplied between a polishing pad affixed to an upper surface plate and a lower surface plate and a main surface of the glass substrate, and the glass substrate and the polishing pad are relative to each other. The method of manufacturing a glass substrate for a magnetic disk including a polishing process for polishing the main surface of the glass substrate by moving the glass substrate, wherein after the polishing process is finished, the pressing force against the glass substrate is a glass substrate. A method of manufacturing a glass substrate for a magnetic disk, wherein the polishing pad is separated from the main surface of the glass substrate while moving the glass substrate and the polishing pad relatively so as to be inclined with respect to the main surface of the glass substrate. is there.

  According to a second aspect of the present invention, the carrier includes: a carrier that holds a glass substrate; and a polishing apparatus that includes a surface plate on which a polishing pad facing the main surface of the glass substrate held by the carrier is attached. A polishing liquid containing abrasive grains is supplied between the main surface of the glass substrate held on the surface and the polishing pad, and the main surface of the glass substrate is polished by relatively moving the glass substrate and the polishing pad. A method of manufacturing a glass substrate for a magnetic disk including a polishing process, wherein the carrier and the surface plate are placed on a plane parallel to the main surface of the glass substrate held by the carrier at the end of polishing. A method for producing a glass substrate for a magnetic disk, wherein the polishing pad is pulled away from a main surface of the glass substrate while being relatively moved.

  2nd aspect of this invention WHEREIN: It is preferable that the said grinding | polishing process pulls the said polishing pad away from the main surface of a glass substrate, stopping the said carrier and rotating the said surface plate on the said parallel surface.

  In the above-described method for manufacturing a glass substrate for a magnetic disk, the quality of the glass substrate can be maintained while satisfying the surface roughness required in the polishing process.

It is a disassembled perspective view of an example of the double-side polish apparatus of this embodiment. It is sectional drawing of an example of the double-side polish apparatus shown in FIG. It is explanatory drawing of the pressing force with respect to the glass substrate in the conventional grinding | polishing process and the 2nd grinding | polishing process of this embodiment.

  Hereinafter, the manufacturing method of the glass substrate for magnetic disks of this invention is demonstrated in detail.

[Polishing equipment]
A glass substrate polishing apparatus using the carrier of this embodiment will be described with reference to FIGS. FIG. 1 is an exploded perspective view of a double-side polishing apparatus. FIG. 2 is a sectional view of the double-side polishing apparatus.

  As shown in FIG. 1, the double-side polishing apparatus has a pair of upper and lower surface plates (that is, an upper surface plate 40 and a lower surface plate 60) that face the moving direction of the surface plate (for example, the vertical direction (Z direction)). ing. An annular glass substrate G is sandwiched between the upper surface plate 40 and the lower surface plate 60, and is held by the carrier 30 by moving one or both of the upper surface plate 40 and the lower surface plate 60. The main surfaces of the glass substrate G are moved relative to each other on a plane parallel to the main surface of the glass substrate G (for example, a horizontal plane (XY plane)). Can be polished. An aqueous solution containing abrasive grains (hereinafter referred to as “polishing liquid” or “polishing slurry”) is supplied between the glass substrate and the surface plate. Hereinafter, when the upper surface plate 40 and the lower surface plate 60 are collectively described, they are simply referred to as a surface plate.

The configuration of the polishing apparatus will be described more specifically with reference to FIGS.
In the polishing apparatus, a polishing pad P is attached to the upper surface of the lower surface plate 60 and the bottom surface of the upper surface plate 40.
The carrier 30 has a holding hole for holding the glass substrate G when the disk-shaped glass substrate G is sandwiched between two surface plates 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 (workpieces). 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 relatively move on the horizontal plane (XY plane). For example, if the sun gear 61 rotates in the CCW (counterclockwise) direction, the carrier 30 rotates in the CW (clockwise) direction, and the internal gear 62 rotates in the CCW direction. As a result, a relative motion on the horizontal plane (XY plane) occurs between the lower surface plate 60 and the glass substrate G. Similarly, the glass substrate G and the upper surface plate 40 may be relatively moved on a horizontal plane (XY plane).

  During relative motion on the horizontal plane (XY plane), the upper surface plate 40 presses the glass substrate G held by the carrier 30 by applying a load in the vertical direction (Z direction). As a result, the polishing pad P is pressed against the glass substrate G. A polishing slurry is supplied between the glass substrate G and the polishing pad P by a pump (not shown).

(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, the rough grinding process of this glass blank is performed. Thereafter, the glass blank is subjected to a shape processing treatment and an end surface polishing treatment. Then, the precise grinding process which uses a fixed abrasive for the glass substrate obtained from the glass blank is performed. Thereafter, a first polishing process, a chemical strengthening process, and a second polishing process are performed on the glass substrate. In the present embodiment, description will be made along the above flow, but all of the above processing is not essential, and these processing can be omitted as appropriate. Hereinafter, each process will be described.

(A) Glass blank molding process 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 performing shape processing on the plate-shaped glass blanks produced by these known production methods.

(B) Rough grinding process In the rough grinding process, specifically, a holding member (for example, a figure) is mounted on a well-known double-side grinding apparatus (for example, a double-side grinding apparatus having the same configuration as in FIG. 2). The main surface on both sides of the glass blank is ground while being held in a holding hole provided in a carrier having the same configuration as in FIG. For example, loose abrasive grains are used as the abrasive. In the rough grinding process, the glass blank is ground so as to approximate the target plate thickness dimension and the flatness of the main surface. The rough grinding process is performed according to the dimensional accuracy or surface roughness of the molded glass blank, and may not be performed depending on the case.

(C) Shape processing processing Next, shape processing 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. Thereby, a side wall surface orthogonal to the main surface and a chamfered surface (intervening surface) connecting the side wall surface and the main surface are formed on the end surface of the glass substrate.

(D) End surface polishing treatment Next, an end surface polishing treatment of the glass substrate is performed. The end surface polishing process 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 relatively moving the polishing brush and the glass substrate. 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 process Next, a fine grinding process 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 apparatus having a configuration similar to that shown in FIGS. Specifically, the main surfaces on both sides of the glass substrate are ground while holding the glass substrate in the holding hole 32 provided in the carrier 30 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. At this time, the pressure with which the upper surface plate 40 or the lower surface plate 60 presses the glass substrate G is preferably 10 to 200 g / cm ² from the viewpoint of effective grinding. The double-sided grinding apparatus has a pair of upper and lower surface plates (upper surface plate and lower surface plate), and fixed abrasive grains containing, for example, diamond abrasive particles are attached to the surfaces of the upper surface plate and the lower surface plate. As the abrasive grains, for example, abrasive grains having an average particle diameter of 5 μm to 50 μm are used. Note that as the abrasive grains, particles such as diamond or an aggregate obtained by solidifying a plurality of particles with a binder such as glass, ceramic, metal, or resin can be used. And, for example, a fixed abrasive can be obtained by sticking a pellet obtained by fixing these abrasive grains using a support material such as a resin to a sheet. The glass substrate is sandwiched between the upper surface plate and the lower surface plate. Then, while supplying the coolant, by moving either the upper surface plate or the lower surface plate, or both, the glass substrate and each surface plate are moved relatively to each other. The main surface can be ground.
In the grinding process of the present embodiment, the grinding surface containing the fixed abrasive 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) First polishing treatment Next, a first polishing treatment is performed on the main surface of the glass substrate. Specifically, the main surface on both sides of the glass substrate is polished while holding the outer peripheral side end surface of the glass substrate in a holding hole provided in the carrier of the double-side polishing apparatus shown in FIGS. The first polishing process uses a polishing pad attached to a surface plate using loose abrasive grains. In the first polishing, for example, cracks and distortions remaining on the main surface when grinding with fixed abrasive grains is performed, or minute surface irregularities generated on the main surface by crystallization treatment are removed. By making the machining allowance within the above range, 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 treatment 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 the chemical strengthening treatment can be determined as appropriate. However, if the polishing treatment is performed after the chemical strengthening treatment, the foreign matter fixed to the surface of the glass substrate by the chemical strengthening treatment can be removed together with the smoothing of the surface. This is particularly preferable because it can be performed. Further, the chemical strengthening treatment may be performed as necessary, and may not be performed.

(H) Second polishing (mirror polishing) treatment Next, the glass substrate after the chemical strengthening treatment is subjected to second polishing. The second polishing is intended for mirror polishing of the main surface. Also in the second polishing, a double-side polishing apparatus having the same configuration as the double-side polishing apparatus used for the first polishing is used. 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 process is different from the first polishing process in that the kind 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 treatment, 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.
The second polishing treatment is preferably performed in that the level of surface irregularities on the main surface of the glass substrate can be further improved. Thus, the glass substrate subjected to the second polishing becomes a glass substrate for a magnetic disk.

The machining allowance by the second polishing is, for example, 2.0 μm or less. At this time, the rotational speed of the carrier 30 is preferably 20 rpm, and the pressing force against the glass substrate G is preferably 0.05 kg / cm ² from the viewpoint of efficient polishing. In addition, the angular velocity of at least one of the glass substrate G and the polishing pad P is preferably within the range where the relative velocity between the glass substrate G and the polishing pad P is 0.3 m / s to 10 m / s.

  FIG. 3 is an explanatory diagram of the pressing force on the glass substrate in the conventional polishing process and the second polishing process of the present embodiment.

  In the conventional polishing process, when the polishing of the main surface of the glass substrate G is finished, the relative movement of the glass substrate G and the surface plate on the horizontal plane is stopped before the polishing pad P is pulled away from the main surface of the glass substrate G. Let Accordingly, as shown in FIG. 3A, the main surface of the glass substrate G from when the relative movement between the glass substrate G and the surface plate stops until the main surface of the glass substrate G moves away from the polishing pad P. Is a force Fz in the vertical direction (Z direction) corresponding to the load L from the surface plate. As a result, the depth of cracks and pits generated when foreign matter exists between the main surface of the glass substrate G and the polishing pad P becomes a depth corresponding to the force Fz.

  On the other hand, in the second polishing process of the present embodiment, when the polishing of the main surface of the glass substrate G is finished, the surface plate is moved relative to the carrier 30 on the horizontal plane (XY plane) while the glass substrate G The polishing pad P is pulled away from the main surface. Therefore, as shown in FIG. 3B, the main surface of the glass substrate G after the relative movement between the glass substrate G and the surface plate stops until the main surface of the glass substrate G moves away from the polishing pad P. The pressing force against is an oblique force F ′. This oblique force F ′ is decomposed into a horizontal plane component F′xy and a vertical component F′z (where F′z <Fz). As a result, the depth of cracks and pits generated when foreign matter, aggregates of abrasive grains, etc. are present between the main surface of the glass substrate G and the polishing pad P becomes shallower than in the conventional polishing process. Thereby, the quality of the glass substrate G can be maintained while satisfying the surface roughness required in the polishing process.

  Here, an example of operation of the double-side polishing apparatus in the second polishing process (first to fourth examples) will be described.

(First example of operation of double-side polishing apparatus in second polishing process)
In the first example of the operation of the double-side polishing apparatus in the second polishing process, after the polishing is finished, the upper surface plate 40 and the lower surface plate 60 are rotated in the CCW direction, and the carrier 30 is stopped while the surface plate is stopped. By moving in the vertical direction (Z direction), the polishing pad P is pulled away from the main surface of the glass substrate G.
In this example, the glass substrate G is stopped and the polishing pad P is rotating (that is, the glass substrate) until the main surface of the glass substrate G leaves the polishing pad P after the polishing is finished. G and polishing pad P are in relative motion on a horizontal plane (XY plane). Therefore, the pressing force against the main surface of the glass substrate G is decomposed into a vertical component and a horizontal plane component by the relative movement between the glass substrate G and the polishing pad P. As a result, even if there is a foreign object between the main surface of the glass substrate G and the polishing pad P, the depth of cracks and pits generated in the vertical direction from the main surface of the glass substrate G is reduced.
Generally, rotating the carrier involves a risk that the glass substrate is detached from the carrier. In particular, in this example, the glass substrate G and the polishing pad P are relatively relative to each other on the horizontal plane (XY plane) without rotating the carrier. Since it is moved, the quality of the glass substrate G can be maintained while satisfying the surface roughness required in the polishing process without causing the above danger.

(Second example of operation of double-side polishing apparatus in second polishing process)
In the second example of the operation of the double-side polishing apparatus in the second polishing process, after the polishing is completed, the upper surface plate 40 and the lower surface plate 60 are rotated in the CCW direction at the first angular velocity ω1, and the carrier 30 is made of CCW. The polishing pad P is pulled away from the main surface of the glass substrate G by moving the surface plate in the vertical direction (Z direction) while rotating in the direction at the second image speed ω2 (where ω2 <ω1).
In this example, the state in which the glass substrate G and the polishing pad P are rotated at different angular velocities from when the polishing is finished until the main surface of the glass substrate G is separated from the polishing pad P (that is, the glass substrate). G and polishing pad P are in relative motion on a horizontal plane (XY plane). Therefore, the pressing force against the main surface of the glass substrate G is decomposed into a vertical component and a horizontal plane component by the relative movement between the glass substrate G and the polishing pad P. As a result, even if there is a foreign object between the main surface of the glass substrate G and the polishing pad P, the depth of cracks and pits generated in the vertical direction from the main surface of the glass substrate G is reduced.
In particular, in this example, the angular velocity (second angular velocity ω2) of the carrier 30 is kept low by the angular velocity (first angular velocity ω1) of the upper surface plate 40 and the lower surface plate 60, and the glass substrate G and the polishing pad P are placed in a horizontal plane. Since the relative movement is performed on the (XY plane), the probability that the glass substrate G is detached from the carrier 30 is reduced, and the quality of the glass substrate G can be maintained while satisfying the surface roughness required in the polishing process. .

(Third example of operation of double-side polishing apparatus in second polishing process)
In the third example of the operation of the double-side polishing apparatus in the second polishing process, after the polishing is finished, the upper surface plate 40 and the lower surface plate 60 are rotated in the CCW direction at the first angular velocity ω1, and the carrier 30 is made of CW. The polishing pad P is pulled away from the main surface of the glass substrate G by moving the surface plate in the vertical direction (Z direction) while rotating in the direction at the third angular velocity ω3 (where ω3 <ω2 <ω1).
In this example, the state in which the glass substrate G and the polishing pad P are rotated in different directions from the end of polishing until the main surface of the glass substrate G is separated from the polishing pad P (that is, the glass substrate). G and polishing pad P are in relative motion on a horizontal plane (XY plane). Therefore, the pressing force against the main surface of the glass substrate G is decomposed into a vertical component and a horizontal plane component by the relative movement between the glass substrate G and the polishing pad P. As a result, even if there is a foreign object between the main surface of the glass substrate G and the polishing pad P, the depth of cracks and pits generated in the vertical direction from the main surface of the glass substrate G is reduced.
In particular, in this example, by rotating the carrier 30 in the opposite direction to the upper surface plate 40 and the lower surface plate 60, the angular velocity (third angular velocity ω3) of the carrier 30 is suppressed to be lower than that in the second example, and the glass substrate G and the polishing plate are polished. Since the pad P is relatively moved on the horizontal plane (XY plane), the probability that the glass substrate G is detached from the carrier 30 is reduced as compared with the second example, and the surface roughness required in the polishing process is satisfied. The quality of the glass substrate G can be maintained.

(Fourth example of operation of double-side polishing apparatus in second polishing process)
In the fourth example of the operation of the double-side polishing apparatus in the second polishing process, after the polishing is finished, the upper surface plate 40 and the lower surface plate 60 are stopped, and the carrier 30 is rotated in the CCW direction while rotating the surface plate. By moving in the vertical direction (Z direction), the polishing pad P is pulled away from the main surface of the glass substrate G.
In this example, the glass substrate G is rotating and the polishing pad P is stopped (that is, the glass substrate) until the main surface of the glass substrate G leaves the polishing pad P after the polishing is finished. G and polishing pad P are in relative motion on a horizontal plane (XY plane). Therefore, the pressing force against the main surface of the glass substrate G is decomposed into a vertical component and a horizontal plane component by the relative movement between the glass substrate G and the polishing pad P. As a result, even if foreign matter or aggregates of abrasive grains are present between the main surface of the glass substrate G and the polishing pad P, the depth of cracks and pits generated in the vertical direction from the main surface of the glass substrate G is shallow. Become.

(Other variations)
In the process of any one of the first to fourth examples of the operation of the double-side polishing apparatus in the second polishing process, polishing is performed until the main surface of the glass substrate G is separated from the polishing pad P after the polishing is finished. The abrasive concentration in the slurry may be increased (for example, a higher concentration polishing slurry may be supplied). By increasing the abrasive grain concentration in the polishing slurry, the pressing force on the glass substrate G is further decomposed into a vertical component and a horizontal plane component by an increase in the abrasive grain concentration. Accordingly, the vertical component of the pressing force with respect to the glass substrate G is further reduced. As a result, even if there is a foreign substance or an aggregate of abrasive grains between the main surface of the glass substrate G and the polishing pad P, the depth of cracks and pits generated in the vertical direction from the main surface of the glass substrate G is further increased. It becomes shallower.

  When the chemical strengthening process and the second polishing process are omitted, any of the first to fourth examples of the operation of the double-side polishing apparatus in the second polishing process in the first polishing process described above. Processing may be executed.

  Thus, in the polishing process in the present embodiment, a polishing liquid containing abrasive grains is supplied between the polishing pad P attached to the upper surface plate 40 and the lower surface plate 60 and the main surface of the glass substrate G, A method of manufacturing a glass substrate for a magnetic disk G including a polishing process for polishing the main surface of the glass substrate G by relatively moving the glass substrate G and the polishing pad P, wherein the polishing process includes polishing After the completion, the polishing pad P of the glass substrate G is moved while the glass substrate G and the polishing pad P are moved relative to each other so that the pressing force against the glass substrate G is obliquely applied to the main surface of the glass substrate G. Pull away from the main surface. As a result, the depth of cracks and pits generated in the vertical direction from the main surface of the glass substrate G becomes shallow. Therefore, the quality of the glass substrate can be maintained while satisfying the surface roughness required in the polishing process.

  As mentioned above, although the manufacturing method of the glass substrate for magnetic discs of this invention was demonstrated in detail, this invention is not limited to the said embodiment and Example, In the range which does not deviate from the main point of this invention, various improvement and a change are carried out. Of course.

30 Carrier 31 Tooth part 32 Holding hole 40 Upper surface plate 42 Upper surface plate support portion 44 Upper surface plate shaft 60 Lower surface plate 61 Sun gear 62 Internal gear

Claims (3)

By supplying a polishing liquid containing abrasive grains between the polishing pad affixed to the upper surface plate and the lower surface plate and the main surface of the glass substrate, and moving the glass substrate and the polishing pad relatively, the glass A method for manufacturing a glass substrate for a magnetic disk including a polishing process for polishing a main surface of a substrate,
After the polishing process is finished, the polishing pad is moved to the glass substrate while relatively moving the glass substrate and the polishing pad so that the pressing force against the glass substrate is applied obliquely to the main surface of the glass substrate. A method for producing a glass substrate for a magnetic disk, characterized by being separated from the main surface of the magnetic disk. The main body of the glass substrate held by the carrier using a carrier that holds the glass substrate and a polishing apparatus that includes a surface plate to which a polishing pad facing the main surface of the glass substrate held by the carrier is attached. For a magnetic disk including a polishing process for polishing a main surface of a glass substrate by supplying a polishing liquid containing abrasive grains between a surface and the polishing pad and relatively moving the glass substrate and the polishing pad. A method of manufacturing a glass substrate,
At the end of polishing, the polishing pad is moved from the main surface of the glass substrate while relatively moving the carrier and the surface plate on a plane parallel to the main surface of the glass substrate held by the carrier. A method for producing a glass substrate for a magnetic disk, characterized by being pulled apart. The polishing process stops the carrier and pulls the polishing pad away from the main surface of the glass substrate while rotating the surface plate on the parallel plane.
The manufacturing method of the glass substrate for magnetic discs of Claim 2.

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