JP5741157B2 - Polishing carrier, glass substrate polishing method using the carrier, and glass substrate manufacturing method - Google Patents

Description

  The present invention relates to a polishing carrier configured to hold a glass substrate in a polishing step, a method for polishing the glass substrate, a method for manufacturing the glass substrate, and a glass substrate for a magnetic recording medium.

Generally, a glass substrate production line used for a magnetic recording medium includes at least the following steps 1 to 7.
(Step 1) After processing a glass base substrate formed by a float method, a fusion method, a redraw method, or a press molding method into a disk shape having a circular hole in the center, the inner peripheral side surface and the outer peripheral side surface are chamfered. .
(Step 2) End face polishing is performed on at least one side surface portion and chamfered portion of the inner periphery or outer periphery of the glass substrate.
(Step 3) The upper and lower main planes of the glass substrate are polished.
(Step 4) The glass substrate is precisely cleaned.
(Step 5) The cleaned glass substrate is dried.
(Step 6) The dried glass substrate is inspected visually or with an optical surface observing device.
(Step 7) The inspected glass substrate is stored in a glass substrate storage container and packaged.

  A glass substrate manufactured by a glass substrate manufacturing line including at least the above-described steps 1 to 7 is shipped as a product.

  In the polishing process, the polishing carrier is rotated (revolved while rotating) by the planetary gear mechanism of the polishing apparatus, so that the glass substrate is inserted by the relative displacement between the glass substrate inserted into the holding hole of the polishing carrier and the polishing surface. The main plane is polished (see, for example, Patent Document 1).

  The polishing carrier is formed in a disk shape from a resin material, and a gear having a plurality of teeth meshing with a sun gear of the polishing device and an internal gear formed on the outer peripheral edge of the polishing device on the outer peripheral side surface Part is provided, and a plurality of glass substrate holding holes are provided on the inner plane of the gear part.

  In the polishing process, the main plane (upper and lower surfaces) of the glass substrate is polished while supplying the polishing liquid to the polishing surface of the polishing pad, and the glass substrate stored and held in each glass substrate holding hole of the polishing carrier is: The main plane is polished when the gear portion of the polishing carrier meshes with the sun gear and the internal gear of the polishing apparatus and rotates. As described above, the polishing carrier is subjected to the rotational driving force by the gear portion and the polishing resistance generated by the relative motion between the glass substrate and the polishing pad, and therefore the strength is insufficient only with the resin material. The abrasive carrier is enhanced in strength by impregnating and laminating a resin material with fibers such as glass.

  Moreover, since the fiber contained in the polishing carrier is hard, there is a problem that the outer peripheral side surface of the glass substrate is damaged by contacting the glass substrate, particularly when the fiber protrudes into the glass substrate holding hole of the polishing carrier. Therefore, in the manufacturing process of the polishing carrier, the polishing carrier is molded using a composite material including fibers and a resin material, and a plurality of glass substrate holding holes are processed in the carrier plane portion. The wall surface is deburred. Thereby, since the inner peripheral wall surface of the glass substrate holding hole is formed on a smooth surface without large unevenness, the outer peripheral side surface of the glass substrate is suppressed to some extent.

JP 2008-6526 A

  In the above conventional polishing carrier, the inner peripheral wall surface of the glass substrate holding hole is deburred, but even if the inner peripheral wall surface of the glass substrate holding hole is processed smoothly, the inner peripheral wall surface and the fiber are the same surface. Therefore, when the outer peripheral side surface of the glass substrate is in contact with the inner peripheral wall surface of the glass substrate holding hole, it is also impossible to sufficiently prevent the hard fiber from coming into contact with the hard fiber. In addition, as the number of uses increases and the number of times the outer peripheral side surface of the glass substrate contacts the inner peripheral wall surface of the glass substrate holding hole increases, the fibers gradually protrude from the inner peripheral wall surface of the glass substrate holding hole. Make a stronger contact.

  Further, in the polishing process, when fine fibers (for example, glass powder) are rubbed and the fibers are rubbed, the broken particles may adhere to the polishing surface or be mixed into the polishing liquid and damage the main plane of the glass substrate.

  Therefore, in view of the above circumstances, the present invention provides a polishing carrier that solves the above problems by arranging fibers only in a region outside a predetermined distance from the inner peripheral wall surface of the glass substrate holding hole, and polishing of the glass substrate using the carrier. An object is to provide a method, a method for producing a glass substrate, and a glass substrate for a magnetic recording medium.

In order to solve the above problems , according to one aspect of the present invention ,
A holding part that is formed using a composite material including a fiber and a resin material and has a glass substrate holding hole for holding a glass substrate, and a gear part that has a plurality of teeth provided on the outer periphery of the holding part In polishing carrier,
A plurality of recesses are arranged on the inner peripheral wall surface of the glass substrate holding hole, and a holding hole buffering region formed only from the resin material on the outside from the inner peripheral wall surface;
A holding hole reinforcing region formed of the composite material outside the holding hole buffering region ;
The gear part has a plurality of recesses on the outer peripheral wall surface of each tooth, a gear part buffering area formed by only the resin material, and a gear part reinforcement formed by the composite material inside the gear part buffering area. A polishing carrier characterized in that it has a region .

  According to the present invention, since fibers do not protrude from the inner peripheral wall surface of the glass substrate holding hole formed in the polishing carrier, the outer peripheral side surface of the glass substrate inserted into the glass substrate holding hole is damaged during the polishing process. Can be prevented. Moreover, since it becomes difficult to generate | occur | produce fragments (for example, glass powder) from a fiber, while being able to suppress that the main plane of a glass substrate is damaged, polishing liquid is hold | maintained at the recessed part of the inner peripheral wall surface of a glass substrate holding hole, Since the friction with respect to the peripheral wall surface is reduced and the glass substrate in the glass substrate holding hole is easily rotated, the parallelism of the main plane of the glass substrate is further increased.

It is a perspective view which shows one Example of a glass substrate. It is a cross-sectional perspective view which shows the cross-sectional shape of a glass substrate. It is a top view which shows one Example of the carrier for grinding | polishing by this invention. It is a longitudinal cross-sectional view in alignment with the XX line in FIG. 3 of carrier 20A for grinding | polishing. It is a longitudinal cross-sectional view which follows the XX line in FIG. 3 of the carrier 20B for grinding | polishing. It is a front view which shows the structure of the double-side polish apparatus in which the carrier for grinding | polishing by this invention is used. It is a perspective view which shows the grinding | polishing process which attached the grinding | polishing carrier to the double-side polish apparatus.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

[Configuration and production of glass substrate]
FIG. 1 is a perspective view showing an embodiment of a glass substrate. As shown in FIG. 1, in the process of manufacturing a glass substrate for a magnetic recording medium, first, a glass substrate mainly composed of SiO ₂ formed by a float method, a fusion method, a redraw method, or a press molding method is used. The glass substrate is manufactured and processed so as to obtain a glass substrate 10 having an outer diameter of 65 mm, an inner diameter of 20 mm, and a plate thickness of 0.635 mm. The glass substrate 10 is formed in a disk shape having a circular hole 12 at the center of both main planes 11, and has an inner peripheral side surface 13 and an outer peripheral side surface 14.

  FIG. 2 is a cross-sectional perspective view showing the cross-sectional shape of the glass substrate. As shown in FIG. 2, the inner peripheral side surface 13 and the outer peripheral side surface 14 of the glass substrate 10 are processed so as to obtain glass substrates having chamfered portions 15 and 16 having a chamfering width of 0.15 mm and a chamfering angle of 45 degrees. Thereafter, the inner peripheral side surface 13, the outer peripheral side surface 14, the inner peripheral chamfered portion 15, and the outer peripheral chamfered portion 16 of the glass substrate 10 are polished using a polishing brush and cerium oxide abrasive grains to remove fine scratches. Next, the abrasive grains adhering to the surface of the glass substrate 10 are washed and removed.

  As a polishing method for polishing the upper and lower main planes 11 of the glass substrate 10, there are the following polishing methods.

  In the glass substrate polishing method of the present embodiment, the polishing surface of the surface plate of the polishing apparatus is pressed against the main flat surface 11 of the glass substrate 10 held in the glass substrate holding hole of the polishing carrier, and the polishing liquid is used as the polishing surface. While being supplied between the glass substrate 10 and the polishing carrier and the polishing surface are relatively moved, the main plane 11 of the glass substrate 10 is polished.

  Here, a specific example of the glass substrate polishing method will be described.

  (I) As the polishing method A, a fixed abrasive polishing method (fixed abrasive polishing) in which the main surface 11 of the glass substrate 10 is polished using a polishing surface and a polishing liquid of a fixed abrasive tool mounted on a surface plate of a polishing apparatus. Process).

  (II) As the polishing method B, a free abrasive polishing method (free abrasive polishing step) in which the main surface 11 of the glass substrate 10 is polished using a polishing liquid containing a polishing surface of a surface plate of a polishing apparatus and abrasive grains. There is.

  (III) As the polishing method C, a mirror surface polishing method (mirror polishing step) in which the main surface 11 of the glass substrate 10 is polished using a polishing liquid containing a polishing surface of a polishing pad mounted on a surface plate of a polishing apparatus and abrasive grains. )

  The polishing methods A to C are appropriately selected according to the purpose. For example, when polishing so that the thickness of the glass substrate is uniform and the flatness of the glass substrate is a desired value, the upper and lower main planes of the glass substrate 10 using a polishing liquid containing free abrasive grains such as alumina abrasive grains. The polishing method B for lapping 11 or the polishing method A for grinding the upper and lower principal planes 11 of the glass substrate 10 using a fixed abrasive tool and a polishing liquid is applied.

Further, when polishing both main planes 11 of the glass substrate 10 for a magnetic recording medium so that, for example, the surface waviness nWa of 60 nm to 160 nm measured using a laser beam having a wavelength of 405 nm is 0.3 nm or less, The polishing method C is applied.
[Glass substrate manufacturing process]
(Shaping process)
A glass base substrate formed by a float method, a fusion method, a redraw method, or a press molding method is processed into a disk shape having a circular hole in the center, and then the inner peripheral side surface and the outer peripheral side surface are chamfered.

(End face polishing process)
The outer peripheral side surface 14 and the outer peripheral chamfered portion 16 of the glass substrate 10 subjected to the chamfering process are polished to remove scratches on the outer peripheral side surface 14 and the outer peripheral chamfered portion 16 to make a mirror surface (outer peripheral end surface polishing). The outer peripheral end surface polishing is performed using, for example, a polishing liquid containing a polishing brush and abrasive grains. The inner peripheral side surface 13 and the inner peripheral chamfered portion 15 of the glass substrate 10 are also preferably polished so as to be a mirror surface (inner peripheral end surface polishing).

(Fixed abrasive polishing process or loose abrasive polishing process)
The upper and lower main planes 11 of the glass substrate 10 on which the end face processing has been finished are polished using a fixed abrasive tool containing diamond abrasive grains and a polishing liquid, or a polishing liquid containing alumina abrasive grains and a lapping plate ( This corresponds to the aforementioned polishing method A (fixed abrasive polishing step) or polishing method B (free abrasive polishing step)).

(Primary mirror polishing step (hereinafter referred to as “primary polishing”))
The upper and lower main planes 11 of the glass substrate 10 are primarily polished by a double-side polishing apparatus (see FIG. 5) described later. In the primary polishing step, for example, a polishing pad made of hard urethane as a polishing tool, and a polishing liquid containing cerium oxide abrasive grains (a polishing liquid composition having an average particle diameter of 1.3 μm as a main component of cerium oxide) and (Corresponding to the polishing method C (mirror polishing step) described above).

  In the primary polishing, the polishing conditions are set so that the main polishing pressure is 10 kPa, the platen rotation speed is 30 rpm, and the polishing time is a total of 40 μm in the thickness direction of the upper and lower main planes 11. Primary polishing is performed under these polishing conditions.

  The glass substrate 10 after the completion of the primary polishing is obtained by the above double-side polishing apparatus using a polishing pad made of soft urethane as a polishing tool and a polishing liquid mainly composed of cerium oxide having an average particle diameter of less than 1.3 μm. The upper and lower main planes 11 are secondarily polished.

(Secondary mirror polishing step (hereinafter referred to as “secondary polishing”))
In the secondary polishing, the polishing process conditions are set so that the polishing process pressure is 10 kPa, the platen rotational speed is 30 rpm, and the polishing time is 5 μm in total in the thickness direction of the upper and lower main planes 11. Secondary polishing is performed under these polishing conditions (corresponding to the polishing method C (mirror polishing step) described above).

(Third mirror polishing step (hereinafter referred to as “third polishing”))
After completion of the secondary polishing, the upper and lower main surfaces 11 are subjected to tertiary polishing by the double-side polishing apparatus using a polishing pad containing soft urethane as a polishing tool and a polishing liquid containing colloidal silica. In the tertiary polishing, the upper and lower main planes 11 of the glass substrate 10 are polished and finished using a polishing liquid mainly composed of colloidal silica having an average primary particle diameter of 20 to 30 nm.

  (Washing and drying step) The glass substrate 10 after the third polishing is sequentially subjected to scrub cleaning with a detergent, ultrasonic cleaning in a state immersed in a detergent solution, ultrasonic cleaning in a state immersed in pure water, Dry with isopropyl alcohol vapor.

(Inspection step) The glass substrate 10 that has been subjected to the cleaning and drying is inspected for defects such as scratches on the upper and lower main planes 11 of the glass substrate 10 and the shape characteristics of the glass substrate 10, and those that passed the inspection are products. Shipped.
[Configuration of polishing carrier]
FIG. 3 is a plan view showing an embodiment of the polishing carrier according to the present invention. As shown in FIG. 3, the polishing carriers 20 </ b> A and 20 </ b> B are formed using a composite material including fibers and a resin material, and have a holding portion 22 having a glass substrate holding hole 21 for holding the glass substrate 10, and holding And a gear portion 24 having a plurality of teeth provided on the outer periphery of the portion 22.

  As the fibers forming the polishing carriers 20A and 20B, for example, glass fibers and metal fibers can be used, and it is preferable to use glass fibers. In the following description, a case where a polishing carrier is formed of a composite material including glass fibers and a resin material is exemplified as an example.

  The polishing carriers 20A and 20B have the same shape, but the material of the gear portion 24 is different as will be described later. One polishing carrier 20A is a carrier for an initial polishing step such as a fixed abrasive polishing step, a loose abrasive polishing step, and a primary polishing step, and only the inner peripheral wall surface 25 of the glass substrate holding hole 21 has glass fibers. It is formed of a resin material that does not. The other polishing carrier 20B is a finish polishing carrier used in the final polishing step (for example, the secondary polishing step or the tertiary polishing step in the mirror polishing step), and the inner peripheral wall surface of the glass substrate holding hole 21 25 and the outer peripheral wall surface 27 of the gear part 24 are formed with the resin material which does not have glass fiber.

  4A is a longitudinal sectional view of the polishing carrier 20A taken along line XX in FIG. As shown in FIG. 4A, the polishing carrier 20A is molded by a composite material in which a fibrous sheet body 30 and a resin impregnated body 40 impregnated in the sheet body 30 are laminated. The fibrous sheet body 30 is formed by laminating glass fibers 32 and a resin impregnated body 40, and a plurality of fibrous sheet bodies 30 of glass fibers 32 are laminated. For the resin impregnated body 40, for example, an epoxy resin, a phenol resin, a polyimide resin, or the like is used.

  Moreover, since the fibrous sheet body 30 has a structure in which fibers are woven so as to intersect with each other in the vertical direction and the horizontal direction, it has strength and rigidity that can withstand polishing.

  The polishing carrier 20A has a holding hole buffering region 50 formed only from a resin material and a holding hole reinforcing region 60 formed from a composite material (the fibrous sheet body 30 and the resin impregnated body 40).

  The holding hole buffering region 50 is easily elastically deformed because a plurality of recesses 26 are arranged on the inner peripheral wall surface 25 of the glass substrate holding hole 21 and no glass fiber is present. Further, the recess 26 is formed in a range La (for example, the depth is La = 2 μm or more) at a predetermined distance from the inner peripheral wall surface 25 to the outside. In addition, the space | interval and arrangement | sequence pattern of several recessed part 26 are decided by the lamination conditions of the arrangement | positioning of the glass fiber in the fiber sheet body 30, and the resin-made impregnation bodies 40.

  In addition, the holding hole buffer region 50 is formed by the resin impregnated body 40 made of only a resin material, and the glass fibers 32 are not present, so that the glass fibers 32 are drawn from the inner peripheral wall surface 25 of the glass substrate holding hole 21. The exposure and contact with the outer peripheral side surface 14 of the glass substrate 10 are prevented. The glass substrate holding hole 21 has a plurality of concave portions 26 arranged on the inner peripheral wall surface 25 and the surface thereof is formed so as to be elastically deformable. Therefore, the glass substrate 10 is held so that the outer peripheral side surface 14 of the glass substrate 10 is not damaged. Is configured to do.

  Further, since the polishing liquid is held in the plurality of recesses 26 formed in the inner peripheral wall surface 25, friction with the outer periphery of the glass substrate 10 inserted into the glass substrate holding hole 21 is reduced, and the glass substrate 10 It becomes easy to rotate. Thereby, since the whole surface of the main plane 11 of the glass substrate 10 is grind | polished uniformly, the parallelism of the up-and-down main plane 11 is raised.

  Since the holding hole reinforcing region 60 is a range Lb outside the holding hole buffering region 50 (a region excluding a predetermined range La from the inner peripheral wall surface 25), the holding hole reinforcing region 60 is formed so as to surround the periphery of the glass substrate holding hole 21. The strength of the glass substrate holding hole 21 is increased. Further, in the polishing carrier 20A, the gear portion 24 is also a gear portion reinforcing region 70 formed of a composite material (fibrous sheet body 30 and resin impregnated body 40), similarly to the holding hole reinforcing region 60. The strength and durability of the gear portion 24 are enhanced. Therefore, in the polishing carrier 20A, since the gear portion 24 is not easily worn, it can withstand high-speed rotation and long-time continuous rotation, and for example, it can be polished by a fixed abrasive polishing process.

  4B is a longitudinal sectional view of the polishing carrier 20B taken along line XX in FIG. As shown in FIG. 4B, the polishing carrier 20B includes a fibrous fibrous sheet body 30 and a resin impregnated body 40 impregnated in the fibrous sheet body 30 in the same manner as the above-described polishing carrier 20A. Molded with laminated composite material. In addition, the polishing carrier 20B is provided with a plurality of recesses 26 and has a holding hole buffering area 50 and a holding hole reinforcing area 60, similarly to the above-described polishing carrier 20A.

In the polishing carrier 20B, unlike the polishing carrier 20A, the gear portion 24 has a plurality of recesses 26 arranged on the outer peripheral wall surface of each tooth, and the gear portion buffering region 80 formed only by the resin material made of the resin impregnated body 40. Have The gear part buffering region 80 is formed outside the gear part reinforcing region 70 formed of a composite material and does not have the glass fiber 32, so that the wear of the sun gear and the internal gear of the polishing apparatus is reduced during driving. In addition, it is possible to prevent generation of glass fiber abrasion powder from the outer peripheral wall surface of the gear portion 24 during driving.
[Configuration of double-side polishing machine]
FIG. 5 is a front view showing a schematic configuration of the double-side polishing apparatus. As shown in FIG. 5, the double-side polishing apparatus 200 is configured to simultaneously polish the upper main plane and the lower main plane of a plurality of glass substrates, and includes a base 220, an upper surface plate 201, and a lower surface plate. 202 and an elevating mechanism 208. A lower surface plate 202 is rotatably supported on an upper portion of the base 220, and a surface plate driving motor for driving the upper surface plate 201 is attached inside the base 220.

  The upper surface plate 201 has an upper polishing surface 130 that is disposed opposite to the upper surface plate 202 and that polishes the upper main plane 11 of the plurality of glass substrates 10 held by the polishing carrier 20A (or the polishing carrier 20B). . Further, the lower surface plate 202 has a lower polishing surface 140 for polishing the lower main plane 11 of the plurality of glass substrates 10 held by the polishing carrier 20A (or the polishing carrier 20B).

  The lifting mechanism 208 is supported by a gate-shaped frame 206 that stands above the base 220, and has a lifting cylinder device 209 that lifts the upper surface plate 201 when the glass substrate is replaced. The lifting cylinder device 209 is attached to the center of the frame 206. The piston rod 254 of the lifting cylinder device 209 extends downward, and a support mechanism 207 that supports the upper surface plate 201 is connected to the lower end portion thereof.

  The support mechanism 207 includes a support column 207 a that extends downward, and a fixed base 207 b that is fixed to the upper surface of the upper surface plate 201. The fixed base 207b is provided with a lock mechanism 260 that is coupled to a groove 262a provided in the rotary shaft 150 of the surface plate drive motor.

  The lock mechanism 260 includes a lock pin 281 coupled to the groove 262a and a shaft 282 that couples the lock pin 281 to the fixed base 207b.

The upper surface plate 201 rises when the glass substrate is replaced by the ascending operation of the piston rod 254 of the elevating cylinder device 209 and descends when polishing. Further, the lifting cylinder device 209 and the surface plate drive motor of the lifting mechanism 208 are controlled by the control unit 210.
[Carrier mounting structure]
FIG. 6 is a perspective view showing a polishing process in which the polishing carrier 20A (20B) is attached to the double-side polishing apparatus 200. FIG. As shown in FIG. 6, the upper surface plate 201 is rotatably supported by the rotation shaft 150. The sun gear 203 provided on the rotating shaft 150 meshes with a gear portion 24 formed on the outer periphery of the plurality of polishing carriers 20A (20B). Further, each tooth of the gear portion 24 of the plurality of polishing carriers 20 </ b> A (20 </ b> B) meshes with the internal gear 205. Each of these gears 203, 24, 205 constitutes a planetary gear mechanism, and each polishing carrier 20A (20B) revolves around the rotating shaft 150 while rotating by the rotation of the sun gear 203 and the internal gear 205.

Thereby, the glass substrate inserted into the glass substrate holding hole 21 of each polishing carrier 20A (20B) for the glass substrate is fixed to the upper polishing surface 130 fixed to the upper surface plate 201 and the lower surface plate 202. Both surfaces are polished while being in sliding contact with the side polishing surface 140.
[Glass substrate polishing procedure]
Here, a procedure for polishing the glass substrate will be described.
(Procedure A1) The polishing carrier 20A is mounted on the lower polishing surface 140. Then, the unpolished glass substrate 10 is inserted into each glass substrate holding hole 21 of the polishing carrier 20A for glass substrate.
(Procedure A2) Next, as shown in FIG. 5, the lifting cylinder device 209 of the double-side polishing apparatus 200 is operated to lower the piston rod 254, and the upper polishing surface 130 of the upper surface plate 201 is covered with the object to be polished. The glass substrate 10 is brought into contact with the upper main plane 11.
(Procedure A3) The lock pin 281 of the lock mechanism 260 is coupled to the groove 262a of the rotary shaft 150. Thereafter, the upper surface plate 201, the lower surface plate 202, the sun gear 203, and the internal gear 205 are rotated by a driving motor, and the glass substrate 10 is inserted into the glass substrate holding holes 21 of the polishing carrier 20A. The lower main plane 11 is polished simultaneously.
(Procedure A4) After polishing of the glass substrate 10, the lifting cylinder device 209 of the double-side polishing apparatus 200 is operated to raise the piston rod 254, and the upper polishing surface 130 of the upper surface plate 201 is polished to the polishing carrier 20A (20B). Separate from. And each glass substrate 10 is taken out.

In the above-described fixed abrasive polishing step, loose abrasive polishing step, primary polishing step to tertiary polishing step, the polishing conditions (type of polishing pad, type of abrasive grain, rotation speed, polishing time, etc.) are changed, respectively. Steps 1 to 4 are performed.
(Procedure A5) When the polishing of the glass substrate 10 is finished, the polishing by the double-side polishing apparatus 200 is stopped, each glass substrate is taken out, washed and transported to the inspection process.
[About polishing carrier processing steps]
[Molding process with resin molding machine]
The polishing carriers 20A and 20B are formed into a plate shape from a composite material including a resin material and glass fibers using a hot press.

[Glass substrate holding hole and gear forming process]
After the molding, as shown in FIG. 3, a plurality of glass substrate holding holes 21 and gear portions 24 are cut and formed on the carrier plane portion by an end mill. Each glass substrate holding hole 21 is formed to have an inner diameter corresponding to the outer diameter into which the glass substrate 10 can be inserted.

[Etching process]
The polishing carrier 20A shown in FIG. 4A is soaked in an etching solution for a predetermined time to remove the glass fibers 32 exposed on the inner peripheral wall surface 25 of each glass substrate holding hole 21. In the etching process, the etching amount is determined by the time of immersion in the etching solution, and the glass fiber 32 having a depth corresponding to the time is dissolved and removed. Moreover, after the etching process is finished, it is desirable that the exposed area ratio of the glass fibers 32 indicating the exposure ratio of the glass fibers 32 on the inner peripheral wall surface 25 is 5% or less. The exposed area ratio is a numerical value obtained by, for example, (exposed area of glass fiber 32 on inner peripheral wall surface 25) ÷ (total area of inner peripheral wall surface 25) × 100 (%).

  In the polishing carrier 20 </ b> A, the glass fiber 32 is present in the gear portion 24 in order to maintain the durability and wear resistance of the gear portion 24 when the rotational driving torque is transmitted to the gear portion 24. When etching the polishing carrier 20A, in order to leave the glass fiber 32 exposed on the outer peripheral wall surface of the gear portion 24, a mask tape is attached to the outer peripheral wall surface 27 of the gear portion 24 or a mask resin material (for example, relatively Coating is performed with a tetrafluoroethylene resin or an epoxy resin having a small friction coefficient. Thus, when the polishing carrier 20A is immersed in the etching solution, the glass fibers 32 exposed on the inner peripheral wall surface 25 of each glass substrate holding hole 21 are removed, but the outer wall surface 27 of the gear portion 24 has a glass Fiber 32 is left.

  The mask tape is peeled off from the gear portion 24 after the etching is finished. However, the mask resin material may be removed or left as it is, and if left as it is, a protective film for protecting the surface of the gear portion 24. And prevents generation of abrasion powder of the glass fiber 32 from the outer peripheral wall surface 27 of the gear portion 24 during driving.

  Further, the polishing carrier 20B shown in FIG. 4B removes the glass fiber 32 exposed on the outer peripheral wall surface 27 of the gear portion 24 by a predetermined dimension La, so that the glass fiber 32 is removed in the final (finish) polishing step. A part is prevented from adhering to the polishing surface or mixed into the polishing liquid.

  The polishing carrier 20 </ b> B is immersed in an etching solution for a predetermined time to remove the glass fibers 32 exposed on the inner peripheral wall surface 25 of each glass substrate holding hole 21 and the outer peripheral wall surface 27 of the gear portion 24. A recess 26 is formed.

[Procedure for etching process]
(Procedure B1) Carrier 20A (20B) in which glass substrate holding hole 21 and gear part 24 are formed is etched in an etching solution (for example, an acidic solution containing 0.01% to 2.0% hydrofluoric acid) for a predetermined time (for example, Soak for about 24 hours). In the present specification,% means mass percentage.

  For example, an etching solution composed of hydrofluoric acid (HF = 0.01% to 2.0%) + nitric acid (HNO3 = 0.02% to 4.0%) is put into a container, and the carrier 20A is inserted from the upper opening of the container. 20B is vertically or horizontally placed and immersed in the etching solution for a predetermined time (for example, about 1 hour). In this case, when a dilute solution of hydrofluoric acid is used, the etching operation can be performed safely.

  The immersion time for the etching treatment with the acidic solution containing 0.01% to 2.0% hydrofluoric acid depends on the etching amount (size) of the glass fiber 32 and the concentration of hydrofluoric acid or nitric acid in the etching solution. As appropriate. For example, when the depth dimension of the recess 26 is set to La = 16 μm to 20 μm, about 20 hours to 24 hours using an etching solution made of hydrofluoric acid (HF = 0.1%) + nitric acid (HNO 3 = 0.2%). Etching for about an hour. Considering the efficiency of the etching process, for example, a method of immersing in an etching solution made of hydrofluoric acid (HF = 1.8%) + nitric acid (HNO3 = 3.7%) for 7 minutes, or hydrofluoric acid (HF = 1) .3%) + nitric acid (HNO3 = 2.6%) is dipped in an etching solution for 15 minutes.

  (Procedure B2) The polishing carriers 20A and 20B are taken out from the etching solution, and the etching solution adhering to the surfaces of the polishing carriers 20A and 20B is washed with a neutralizing solution. By this etching process, the holding hole buffer region 50 and the gear portion buffer region 80 described above are formed.

  In the polishing carriers 20A and 20B, glass fibers 32 in a predetermined range (for example, La≈16 μm to 20 μm) are removed from the inner peripheral wall surface 25 of each glass substrate holding hole 21 by the above etching process. On the inner peripheral wall surface 25 of the hole 21, a plurality of recesses 26 are left in the space from which the glass fibers 32 have been removed.

  In addition, since one polishing carrier 20A is masked with a mask tape attached to the outer peripheral wall surface 27 of the gear portion 24 or coated with a mask resin material, the outer peripheral wall surface 27 of the gear portion 24 is coated with glass. The fiber 32 is exposed. In the other polishing carrier 20B, since the masking process is not performed on the gear part 24, the glass fiber 32 in a predetermined range (for example, La≈16 μm to 20 μm) is removed by the etching process from the outer peripheral wall surface 27 of the gear part 24 to the inside. Is done.

  In addition, although the present Example demonstrated the case where the method of melt | dissolving the glass fiber 32 exposed to the inner peripheral wall surface 25 of the glass substrate holding hole 21 to predetermined range La by being immersed in etching liquid was demonstrated, glass fiber 32 A processing method other than immersing in an etching solution (for example, a method of applying hydrogen fluoride, sodium hydrogen fluoride, or the like to the inner peripheral wall surface 25 or the gear portion 24 of the glass substrate holding hole 21) It may be used.

In the present embodiment, the glass fiber removal method has been described for the polishing carriers 20A and 20B containing the glass fiber 32, but the scope of application of the present invention is not limited to this. For example, even if an abrasive carrier containing metal fibers in a resin base material is used, an inorganic acid or the like is used to elute and remove the metal fibers exposed on the inner peripheral wall surface 25 of the glass substrate holding hole 21 and the outer peripheral wall surface 27 of the gear portion 24. Good.
[Inspection result of glass substrate polished using polishing carriers 20A and 20B]
(Experimental result of fixed abrasive polishing process)
Table 1 shows the case where the polishing carrier 20A (with gear part masking) is attached to the polishing apparatus 200 and the glass substrate 10 is polished with fixed abrasive (Example No. 1) and the conventional polishing carrier (without etching treatment). A comparison result with the case where the glass substrate 10 is polished with fixed abrasive (Comparative Example No. 2) is shown.

表１より、研磨用キャリア２０Ａを用いてガラス基板１０を固定砥粒研磨した場合、ガラス基板１０の外周側面１４の表面粗さ曲線の最大谷深さＲｖ＝０．０６μｍ〜０．０８μｍであるのに対して、従来の研磨用キャリアではガラス基板１０の表面粗さ曲線の最大谷深さＲｖ＝０．１５μｍ〜０．２３μｍである。尚、外周側面１４の表面粗さは、例えば触針式表面粗さ測定器（東京精密社製、ＳＵＲＦＣＯＭ １４００Ｄ）により、Ｒ０．２μｍの触針を外周側面１４の表面で主平面１１と垂直の方向に０．２ｍｍ走査させて測定する。

From Table 1, when the glass substrate 10 is fixed abrasive-polished using the polishing carrier 20A, the maximum valley depth Rv of the surface roughness curve of the outer peripheral side surface 14 of the glass substrate 10 is 0.06 μm to 0.08 μm. On the other hand, in the conventional polishing carrier, the maximum valley depth Rv of the surface roughness curve of the glass substrate 10 is 0.15 μm to 0.23 μm. Incidentally, the surface roughness of the outer peripheral side surface 14 is perpendicular to the main plane 11 on the surface of the outer peripheral side surface 14 by using, for example, a stylus type surface roughness measuring instrument (manufactured by Tokyo Seimitsu Co., Ltd., SURFCOM 1400D). Measurement is performed by scanning 0.2 mm in the direction.

In addition, when the glass substrate 10 is polished using the polishing carrier 20A, concave-shaped defects (defects such as scratches having a maximum diameter or vertical and horizontal dimensions of 10 μm or more) generated per unit area of the outer peripheral side surface 14 of the glass substrate 10 Whereas the number n is n = 0, in the conventional polishing carrier, the number n of concave defects generated per unit area of the outer peripheral side surface 14 of the glass substrate 10 is n = 2. The number of concave defects is determined by counting, for example, concave defects such as scratches having a maximum diameter or vertical and horizontal dimensions of 10 μm or more generated per unit area (for example, per 1 mm ² ) using an optical microscope. In the outer peripheral side surface 14 of the glass substrate 10, it is desirable that the number of concave defects having a size of 10 μm or more is 5 / mm ² or less.

  Further, when the glass substrate 10 is fixed abrasive-polished using the polishing carrier 20A, the parallelism a of the upper and lower main planes 11 of the glass substrate 10 is 0 μm, whereas in the conventional polishing carrier, the glass substrate 10 The parallelism a of the upper and lower main planes 11 was 1 μm.

  As a method for measuring the parallelism a in this example, the thickness of the glass substrate 10 was measured at two locations of 0 °, 90 °, 180 °, and 270 ° in the circumferential direction at a total of 8 micrometers (MDC-Mitutoyo MDC-). MJ / PJ). Then, the difference between the maximum thickness value and the minimum thickness value is obtained to obtain the parallelism a.

As a result of this experiment, the glass substrate 10 subjected to the fixed abrasive polishing process using the polishing carrier 20A has the surface roughness of the outer peripheral side surface 14, the number of concave defects on the outer peripheral side surface 14, and the parallelism a of the upper and lower main planes 11. It can be seen that the results are better than those of the conventional polishing carrier.
(Experimental result of mirror polishing process)
Table 2 shows the case where the polishing carrier 20A is attached to the polishing apparatus 200 and the glass substrate 10 is subjected to primary polishing or secondary polishing (Example No. 3) and the glass substrate 10 is polished using a conventional polishing carrier. A comparison result with (comparative example No. 4) is shown.

表２より、研磨用キャリア２０Ａを用いてガラス基板１０を１次研磨した場合、ガラス基板１０の外周側面１４の表面粗さ曲線の最大谷深さＲｖ＝０．０６μｍ〜０．０８μｍであるのに対して、従来の研磨用キャリアではガラス基板１０の外周側面１４の表面粗さ曲線の最大谷深さＲｖ＝０．１５μｍ〜０．４２μｍである。尚、表面粗さの測定方法は、上記固定砥粒研磨工程の場合と同じである。

From Table 2, when the glass substrate 10 is primarily polished using the polishing carrier 20A, the maximum valley depth Rv = 0.06 μm to 0.08 μm of the surface roughness curve of the outer peripheral side surface 14 of the glass substrate 10 is obtained. On the other hand, in the conventional polishing carrier, the maximum valley depth Rv of the surface roughness curve of the outer peripheral side surface 14 of the glass substrate 10 is 0.15 μm to 0.42 μm. In addition, the measuring method of surface roughness is the same as the case of the said fixed abrasive polishing process.

In addition, when the glass substrate 10 is subjected to primary polishing (or secondary polishing) using the polishing carrier 20A, concave defects generated per unit area (for example, per 1 mm ² ) of the outer peripheral side surface 14 of the glass substrate 10 Whereas the number n is n = 0, the number n of concave defects generated per unit area (for example, per 1 mm ² ) of the outer peripheral side surface 14 of the glass substrate 10 in the conventional polishing carrier is n = 10 pieces. The method for measuring the number of concave defects is the same as that in the fixed abrasive polishing step. In the outer peripheral side surface 14 of the glass substrate 10, it is desirable that the number of concave defects having a size of 10 μm or more is 5 / mm ² or less.

  In addition, when the glass substrate 10 is primarily polished using the polishing carrier 20A, the parallelism b of the upper and lower main planes 11 of the glass substrate 10 is a = 0.3 μm, whereas in the conventional polishing carrier The parallelism b of the upper and lower main planes 11 of the glass substrate 10 is a = 0.9 μm. The parallelism b is measured using a laser interferometer (for example, a product name: Fizeau interferometer for plane measurement, G102S, manufactured by Fujinon).

As a result of this experiment, the glass substrate 10 polished using the polishing carrier 20A is conventional in terms of the surface roughness of the outer peripheral side surface 14, the number of concave defects on the outer peripheral side surface 14, and the parallelism b of the upper and lower main planes 11. It can be seen that better results are obtained than the polishing carrier.
(Experimental result of finish polishing process)
Table 3 shows a case where a polishing carrier 20B (without gear portion masking) is attached to the polishing apparatus 200 to polish the glass substrate 10 (Example No. 5) and a case where the glass substrate 10 is polished using a conventional polishing carrier. A comparison result with (comparative example No. 6) is shown. The finish polishing step is secondary polishing when performing primary to secondary polishing, and is tertiary polishing when performing primary to secondary polishing, and is performed at the end of the polishing step. It means finish polishing.

表３より、研磨用キャリア２０Ｂを用いてガラス基板１０の仕上研磨を行った場合、ガラス基板１０の外周側面１４の表面粗さ曲線の最大谷深さＲｖ＝０．０６μｍ〜０．０８μｍであるのに対して、従来の研磨用キャリアではガラス基板１０の外周側面１４の表面粗さが表面粗さ曲線の最大谷深さＲｖ＝０．１５μｍである。尚、表面粗さの測定方法は、上記固定砥粒研磨工程、鏡面研磨工程の場合と同じである。

From Table 3, when finishing polishing of the glass substrate 10 using the polishing carrier 20B, the maximum valley depth Rv = 0.06 μm to 0.08 μm of the surface roughness curve of the outer peripheral side surface 14 of the glass substrate 10 is obtained. On the other hand, in the conventional polishing carrier, the surface roughness of the outer peripheral side surface 14 of the glass substrate 10 is the maximum valley depth Rv = 0.15 μm of the surface roughness curve. In addition, the measuring method of surface roughness is the same as the case of the said fixed abrasive polishing process and mirror polishing process.

Further, when the glass substrate 10 is finish-polished using the polishing carrier 20B, the number of concave defects n generated per unit area (for example, per 1 mm ² ) of the outer peripheral side surface 14 of the glass substrate 10 is n = 0. On the other hand, in the conventional polishing carrier, the number n of concave defects generated per unit area (for example, per 1 mm ² ) of the outer peripheral side surface 14 of the glass substrate 10 is n = 8. The method for measuring the number of concave defects is the same as in the fixed abrasive polishing step and the mirror polishing step.

  Further, when the glass substrate 10 is finish-polished using the polishing carrier 20A, the number na of scratches on both main planes 11 of the glass substrate 10 is na = 0, whereas the conventional polishing carrier is made of glass. The number na of scratches on both main planes of the substrate 10 is na = 5. In addition, the measuring method of the crack of the upper and lower main plane 11 is performed by an inspector's visual observation. At that time, the presence of scratches is inspected at a brightness of 300 k lux with a metal haloid lamp, and scratches having a size (length) of 5 μm or more are counted.

  As a result of this experiment, the glass substrate 10 finish-polished using the polishing carrier 20B has the conventional surface roughness on the outer peripheral side surface 14, the number of concave defects on the outer peripheral side surface 14, and the scratches on both main planes 11. It can be seen that better results are obtained than the polishing carrier.

Thus, by polishing the glass substrate 10 using the polishing carriers 20A and 20B of the present invention, the surface roughness of the outer peripheral side surface 14 of the glass substrate 10, the number of concave defects on the outer peripheral side surface 14, both main planes 11 The degree of parallelism between the scratches and the two principal planes 11 is improved. Further, even if the amount of polishing agent (for example, rare earth (rare earth) such as cerium oxide (CeO ₂ )) contained in the polishing liquid is reduced to reduce the concentration of the polishing agent in the polishing liquid, the outer peripheral side surface of the glass substrate 10 Thus, the problem of increasing the surface roughness of 14 and the number of concave defects on the outer peripheral side surface 14 does not occur, and the polishing quality can be maintained. Therefore, the abrasive concentration of the polishing liquid used in the polishing process can be made lower than before, reducing the consumption of valuable abrasives, keeping the costs in the polishing process low, and saving the abrasives. It becomes possible.

[About parallelism a and b]
Here, the parallelism a and b described above will be described.

  The parallelisms a and b of both main planes 11 of the glass substrate 10 for a magnetic recording medium manufactured by the method for manufacturing a glass substrate according to the present invention are such that the plate thickness in each region of the glass substrate for a magnetic recording medium is uniform. It is excellent, and it is inferior so that the board thickness in each area | region is non-uniform | heterogenous (a board thickness deviation is large).

  The parallelism of both main planes 11 of the glass substrate 10 for magnetic recording media is measured using a measuring machine such as a micrometer, a laser displacement meter, a laser interferometer.

  The measurement of the parallelism a by the fixed abrasive polishing process using a micrometer or a laser displacement meter is performed by measuring the plate thickness at a plurality of points arbitrarily determined in the main plane 11 of the glass substrate 10 for magnetic recording media. The difference between the thickness value and the minimum thickness value is obtained.

  Since the laser interferometer uses the wavelength of light as a rule, it can measure the parallelism b by the mirror polishing process with high accuracy. Moreover, since the parallelism b of both main planes 11 of the glass substrate 10 for magnetic recording media can be measured by one data acquisition, it is excellent in measurement efficiency.

  The measurement of the parallelism b of both main planes 11 of the glass substrate 10 for magnetic recording media using a laser interferometer is obtained by observing interference fringes formed by the phase difference of the reflected light reflected from both main planes 11. This is done by analyzing the interference fringes. The bright and dark interference fringes observed with the laser interferometer are contour lines, and the interval is determined by the wavelength of the light source and the incident angle.

  The smaller the number of interference fringes observed, the better the parallelism of both main planes 11 of the glass substrate 10 for magnetic recording media, that is, the parallelism b of both main planes 11 of the glass substrate 10 for magnetic recording media. It means that the thickness deviation in the area where the measurement is performed is small, and the thickness distribution in the main plane 11 of the same glass substrate 10 is excellent.

  In the above embodiment, the process of manufacturing a glass substrate for a magnetic recording medium has been described as an example. However, the present invention is not limited to this, and the present invention is also applied to each process of polishing a glass substrate used for other purposes. Of course, can be applied.

  Specific examples of glass substrates to which the present invention can be applied include glass substrates for magnetic recording media, photomasks, displays such as liquid crystals and organic EL, and optical components such as optical pickup elements and optical filters. As mentioned.

DESCRIPTION OF SYMBOLS 10 Glass substrate 11 Main plane 12 Circular hole 13 Inner peripheral side surface 14 Outer peripheral side surface 15 Inner peripheral chamfered portion 16 Outer peripheral chamfered portion 20A, 20B Polishing carrier 21 Glass substrate holding hole 22 Holding portion 24 Gear portion 25 Inner peripheral wall surface 26 Recessed portion 27 Outer periphery Wall surface 30 Fibrous sheet body 32 Fiber 40 Resin impregnated body 50 Holding hole buffering area 60 Holding hole reinforcing area 70 Gear part reinforcing area 80 Gear part buffering area 130 Upper polishing surface 140 Lower polishing surface 150 Rotating shaft 200 Double-side polishing apparatus 201 Upper surface plate 202 Lower surface plate 203 Sun gear 205 Internal gear 206 Frame 207 Support mechanism 208 Lift mechanism 209 Lift cylinder device 210 Control unit 220 Base 254 Piston rod 260 Lock mechanism

Claims (10)

A holding part that is formed using a composite material including a fiber and a resin material and has a glass substrate holding hole for holding a glass substrate, and a gear part that has a plurality of teeth provided on the outer periphery of the holding part In polishing carrier,
A plurality of recesses are arranged on the inner peripheral wall surface of the glass substrate holding hole, and a holding hole buffering region formed only from the resin material on the outside from the inner peripheral wall surface;
A holding hole reinforcing region formed of the composite material outside the holding hole buffering region ;
The gear part has a plurality of recesses on the outer peripheral wall surface of each tooth, a gear part buffering area formed by only the resin material, and a gear part reinforcement formed by the composite material inside the gear part buffering area. polishing carrier and having a region. The polishing carrier according to claim 1 , wherein an exposed area ratio of the fibers indicating an exposed ratio of the fibers on the inner peripheral wall surface is 5% or less. The recess, polishing carrier according to claim 1 or 2 depth from the inner peripheral wall surface is 2μm or more which is arranged in said peripheral wall. The carrier for polishing according to any one of claims 1 to 3 , wherein the fibers are glass fibers or metal fibers. The glass substrate is polished carrier according to any one of claims 1-4 in a central portion which is a glass substrate for a magnetic recording medium of a disk shape having a circular hole. The polishing surface of the surface plate of the polishing apparatus is pressed against the main plane of the glass substrate held in the glass substrate holding hole of the polishing carrier, and a polishing liquid is supplied between the polishing surface and the glass substrate, and In the glass substrate polishing method of polishing the main plane of the glass substrate by relatively moving the polishing carrier and the polishing surface,
The polishing carrier, the polishing method for a glass substrate, which is a polishing carrier according to any one of claims 1-5. A method for polishing a glass substrate according to claim 6 ,
A polishing method for a glass substrate, wherein the main surface of the glass substrate is polished by a polishing process using a polishing surface of a fixed abrasive tool mounted on a surface plate of the polishing apparatus and a polishing liquid. A method for polishing a glass substrate according to claim 6 ,
A polishing method for a glass substrate, comprising polishing a main surface of the glass substrate by a free abrasive polishing process using a polishing liquid containing a polishing surface of a surface plate of the polishing apparatus and abrasive grains. A method for polishing a glass substrate according to claim 6 ,
A polishing method for a glass substrate, wherein a main surface of the glass substrate is polished by a mirror polishing process using a polishing liquid containing a polishing surface and an abrasive containing a polishing pad mounted on a surface plate of the polishing apparatus. In a method of manufacturing a glass substrate, comprising: a shape processing step of processing a glass plate into a glass substrate having a desired shape; a polishing step of polishing a main plane of the glass substrate; and a cleaning step of the glass substrate.
The said grinding | polishing process grinds the said main plane in the state which inserted the said glass substrate in the glass substrate holding hole of the carrier for grinding | polishing in any one of Claims 1-5 , The manufacturing method of the glass substrate characterized by the above-mentioned.

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