JP6042453B2 - Manufacturing method of glass substrate for information recording medium - Google Patents

Description

  The present invention relates to a method for producing a glass substrate for an information recording medium.

  An information recording medium is mounted on an information recording device such as a computer. In general, a glass substrate is used to manufacture an information recording medium. A magnetic thin film layer is formed on the glass substrate. Information can be recorded in the magnetic thin film layer by magnetizing the magnetic thin film layer with a magnetic head. In recent years, the recording density of information recording media tends to increase. For example, one 2.5 inch information recording medium having a recording capacity of 500 GB has been developed, and a glass substrate for an information recording medium having higher surface quality is required.

  When manufacturing a glass substrate for information recording media, a double-side polishing apparatus is used to polish the surface of the glass substrate. The glass substrate is held by a carrier (also referred to as a polishing carrier) as disclosed in, for example, Japanese Patent Application Laid-Open No. 2008-006526 (Patent Document 1). With the glass substrate held by the carrier, the surface of the glass substrate is polished by the polishing pad of the double-side polishing apparatus.

JP 2008-006526 A

  An object of this invention is to provide the manufacturing method of the glass substrate for information recording media which has higher surface quality.

The method for manufacturing a glass substrate for information recording medium according to the first aspect of the present invention includes a first set step of arranging a polishing carrier and a glass substrate on a surface plate of a double-side polishing machine, and both a sun gear and an internal gear. The carrier is rotated using the sun gear and the internal gear in a state where the outer periphery of the carrier is engaged with the tooth surface, and the glass substrate is slidably contacted with the polishing surface of the polishing pad so that the surface of the glass substrate is touched. A first sliding step for polishing, a second setting step for placing one of the carrier and the other carrier and another glass substrate on the surface plate of the double-side polishing machine, the sun gear and the internal Using the sun gear and the internal gear with the outer circumference of the one carrier engaged with both tooth surfaces of the gear. A second sliding step in which the other glass substrate is slidably contacted with the polishing surface of the polishing pad to polish the surface of the other glass substrate, and the first sliding step. If the position in the direction parallel to the axial direction of the sun gear is referred to as height after the second sliding step, the first sliding of the tooth surfaces of the sun gear is performed. The portion where the carrier meshed in the process is a first location, and the portion of the tooth surface of the sun gear where the one carrier should mesh in the second sliding step is the second location, and the internal gear The portion of the tooth surface where the carrier meshed in the first sliding step is defined as a third location, and the one carrier should mesh in the second sliding step of the tooth surface of the internal gear. Part If there are four locations, the height direction position of the second location in the tooth surface of the sun gear is different from the first location, and the height direction of the fourth location in the tooth surface of the internal gear. And a height changing step having at least one of the position of the third position, and in the height changing step, the sun gear and the internal gear are turned upside down in the axial direction. Is done .

Preferably, the depth of the groove formed on the tooth surface of the sun gear and / or the tooth surface of the internal gear is set after the first sliding step and before the height changing step. A measuring step for measuring, wherein the concave groove is formed by rotating the carrier in a state where the outer periphery of the carrier is engaged with both tooth surfaces of the sun gear and the internal gear in the first sliding step. The first setting step and the first sliding step are performed until the depth of the concave groove measured in the measurement step is 0.14 or more in percentage with respect to the outer diameter of the carrier. Repeated .

According to a second aspect of the present invention, there is provided a method for manufacturing a glass substrate for an information recording medium, comprising: a first setting step of arranging a polishing carrier and a glass substrate on a surface plate of a double-side polishing machine; and both a sun gear and an internal gear. The carrier is rotated using the sun gear and the internal gear in a state where the outer periphery of the carrier is engaged with the tooth surface, and the glass substrate is slidably contacted with the polishing surface of the polishing pad so that the surface of the glass substrate is touched. A first sliding step for polishing, a second setting step for placing one of the carrier and the other carrier and another glass substrate on the surface plate of the double-side polishing machine, the sun gear and the internal Using the sun gear and the internal gear with the outer circumference of the one carrier engaged with both tooth surfaces of the gear. A second sliding step in which the other glass substrate is slidably contacted with the polishing surface of the polishing pad to polish the surface of the other glass substrate, and the first sliding step. If the position in the direction parallel to the axial direction of the sun gear is referred to as height after the second sliding step, the first sliding of the tooth surfaces of the sun gear is performed. The portion where the carrier meshed in the process is a first location, and the portion of the tooth surface of the sun gear where the one carrier should mesh in the second sliding step is the second location, and the internal gear The portion of the tooth surface where the carrier meshed in the first sliding step is defined as a third location, and the one carrier should mesh in the second sliding step of the tooth surface of the internal gear. Part If there are four locations, the height direction position of the second location in the tooth surface of the sun gear is different from the first location, and the height direction of the fourth location in the tooth surface of the internal gear. And a height changing step having at least one of the position of the third position, and after the first sliding step and before the height changing step. And a measuring step of measuring a depth of the sun gear tooth surface and / or a groove groove formed in the tooth surface of the internal gear, wherein the groove groove is formed in the first sliding step. The depth of the concave groove measured in the measuring step is formed by rotating the carrier with the outer periphery of the carrier meshing with both tooth surfaces of the internal gear. The first setting step and the first sliding step are repeated until the percentage becomes 0.14 or more with respect to the outer diameter of the carrier .

Preferably, in the height changing step, spacer members are respectively provided between the sun gear and the member supporting the sun gear and between the internal gear and the member supporting the internal gear .

  Preferably, in the second setting step and the second sliding step immediately after the height changing step, the other carrier in an unused state is used as the one carrier.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the glass substrate for information recording media which has higher surface quality can be obtained.

1 is a perspective view showing a glass substrate for information recording medium manufactured using the method for manufacturing a glass substrate for information recording medium in Embodiment 1. FIG. 1 is a perspective view showing a magnetic disk (information recording medium) including a glass substrate for information recording medium manufactured using the method for manufacturing a glass substrate for information recording medium in Embodiment 1. FIG. FIG. 3 is a flowchart showing a method for manufacturing the glass substrate for information recording medium in the first embodiment. It is a flowchart which shows the detail of 2nd polishing process S18 contained in the manufacturing method of the glass substrate for information recording media in Embodiment 1. FIG. It is a side view which shows the double-side polish apparatus used by 2nd polishing process S18 in Embodiment 1. FIG. It is arrow sectional drawing along the VI-VI line in FIG. It is a figure which expands and shows the area | region enclosed by the VII line in FIG. It is arrow sectional drawing along the VIII-VIII line in FIG. It is sectional drawing which shows a mode when the double-side polish apparatus used by 2nd polishing process S18 in Embodiment 1 is performing the polishing process. It is a perspective view which shows the state which made the meshing tooth of the carrier mesh | engaged with the tooth | gear surface of the internal gear used for the double-side polish apparatus shown in FIG. FIG. 11 is a diagram schematically showing a state when the tooth surface of the internal gear is viewed from the direction of arrow XI in FIG. 10 (a diagram in which the tooth surface is developed in the circumferential direction). It is a perspective view which shows the state after use of the internal gear shown in FIG. FIG. 13 is a diagram schematically showing a state when the tooth surface of the internal gear is viewed from the direction of arrow XIII in FIG. 12 (a diagram in which the tooth surface is developed in the circumferential direction). It is a figure which shows typically the state after use of the internal gear shown in FIG. It is a figure which shows the state after use of the internal gear shown in FIG. 14 (figure which developed the tooth surface in the circumferential direction). FIG. 16 is a diagram schematically illustrating a state after use of the internal gear illustrated in FIG. 15 (a diagram in which a tooth surface is developed in a circumferential direction). It is sectional drawing which shows the state after the height change process included in the manufacturing method of the glass substrate for information recording media in Embodiment 1 was performed. It is sectional drawing which shows the other mode when the double-side polish apparatus used by 2nd polish process S18 in Embodiment 1 is grinding | polishing. It is sectional drawing which shows the state after the height change process included in the manufacturing method of the glass substrate for information recording media in Embodiment 2 was performed. FIG. 11 is a flowchart showing details of a second polishing step S18A included in the method for manufacturing a glass substrate for information recording medium in the third embodiment. It is a figure which shows the experimental condition which concerns on an experiment example. It is a figure which shows the experimental result which concerns on an experiment example.

  Embodiments based on the present invention will be described below with reference to the drawings. In the description of each embodiment, when referring to the number, amount, and the like, the scope of the present invention is not necessarily limited to the number, the amount, and the like unless otherwise specified. In the description of each embodiment, the same parts and corresponding parts are denoted by the same reference numerals, and redundant description may not be repeated.

[Embodiment 1]
1 and 2, a glass substrate 1G manufactured using the method for manufacturing a glass substrate for information recording medium according to the present embodiment, and a magnetic disk 1 including the glass substrate 1G (information recording medium) ).

(Glass substrate 1G)
As shown in FIG. 1, a glass substrate 1G (glass substrate for information recording medium) used for a magnetic disk 1 (see FIG. 2) has a disk shape with a hole 11 formed in the center. Glass substrate 1 </ b> G includes front main surface 14, back main surface 15, inner peripheral end surface 13, and outer peripheral end surface 12. A chamfer surface 13a having a tapered shape is provided on a portion of the inner peripheral end surface 13 on the front main surface 14 side, and a chamfer surface 13b having a tapered shape is provided on a portion on the back main surface 15 side of the inner peripheral end surface 13 (see FIG. 2).

  The glass substrate 1G has a size of, for example, 0.8 inch, 1.0 inch, 1.8 inch, 2.5 inch, or 3.5 inch. The thickness of the glass substrate 1G is, for example, 0.30 mm to 2.2 mm. Glass substrate 1G in the present embodiment has an outer diameter of about 65 mm, an inner diameter of about 20 mm, and a thickness of about 0.8 mm. The thickness of the glass substrate 1G is a value calculated by averaging the values measured at a plurality of arbitrary points that are point-symmetric on the glass substrate 1G.

(Magnetic disk 1)
As shown in FIG. 2, the magnetic disk 1 includes a glass substrate 1 </ b> G and a magnetic thin film layer 16 (magnetic recording layer) formed on the front main surface 14. The magnetic thin film layer 16 in the present embodiment is formed only on the front main surface 14, but may be further formed on the back main surface 15. The magnetic thin film layer 16 is formed by spin-coating a thermosetting resin in which magnetic particles are dispersed on the front main surface 14 of the glass substrate 1G (spin coating method). The magnetic thin film layer 16 may be formed using a sputtering method or an electroless plating method.

  The film thickness of the magnetic thin film layer 16 formed on the front main surface 14 of the glass substrate 1G is about 0.3 μm to about 1.2 μm in the case of the spin coating method, and about 0.04 μm to about 0.00 in the case of the sputtering method. In the case of the electroless plating method, the thickness is about 0.05 μm to about 0.1 μm. As the magnetic material used for forming the magnetic thin film layer 16, it is preferable to use Co having a high crystal anisotropy and a Co-based alloy with Ni or Cr added for the purpose of adjusting the residual magnetic flux density. An FePt-based material may be used as a magnetic material suitable for heat-assisted recording.

  In order to improve the sliding with respect to the magnetic head, a thin lubricant may be coated on the surface of the magnetic thin film layer 16. Examples of the lubricant include those obtained by diluting perfluoropolyether (PFPE) with a freon-based solvent. You may provide a base layer and a protective layer as needed.

  The underlayer is selected according to the type of magnetic film. Examples of the material for the underlayer include at least one material selected from nonmagnetic metals such as Cr, Mo, Ta, Ti, W, V, B, Al, and Ni. The underlayer may have a single-layer structure or a multi-layer structure in which the same or different layers are stacked. Examples of the multilayer structure include Cr / Cr, Cr / CrMo, Cr / CrV, NiAl / Cr, NiAl / CrMo, and NiAl / CrV.

  Examples of the protective layer that prevents wear and corrosion of the magnetic thin film layer 16 include a Cr layer, a Cr alloy layer, a carbon layer, a hydrogenated carbon layer, a zirconia layer, and a silica layer. These protective layers can be formed continuously with an in-line type sputtering apparatus, such as an underlayer and a magnetic film. These protective layers may have a single layer structure, or may have a multilayer structure in which the same or different layers are stacked.

Another protective layer may be formed on the protective layer or instead of the protective layer. For example, instead of the protective layer, while tetraalkoxysilane is diluted with an alcohol solvent, colloidal silica fine particles are dispersed and applied onto the Cr layer, and further baked to form a silicon oxide (SiO ₂ ) layer. You may form on it.

(Manufacturing method of glass substrate 1G)
With reference to FIG. 3, the manufacturing method of the glass substrate 1G which concerns on this Embodiment is demonstrated. The manufacturing method includes steps S10 to S19. In the glass melting step S10, the glass material is melted. In the molding step S11, the molten glass material is press-molded using the upper mold and the lower mold. A glass substrate is obtained by molding. The glass substrate may be cut out from the plate glass. The composition of the glass substrate is, for example, aluminosilicate glass.

  In the first lapping step S12, both main surfaces of the glass substrate are lapped using a double-sided lapping device having a planetary gear mechanism. The lap platen is pressed from above and below against the glass substrate, and the glass substrate and the lap platen are relatively moved while supplying abrasive grains and grinding liquid onto both main surfaces of the glass substrate. As the abrasive, alumina or the like is used. By the lapping process, a glass substrate having a substantially flat surface shape is obtained.

  In the coring step S13, a hole is formed in the center of the glass substrate using a cylindrical diamond drill. Using a diamond grindstone, chamfering is performed on the inner peripheral end surface and the outer peripheral end surface of the glass substrate. In 2nd lapping process S14, the lapping process similar to 1st lapping process S12 is given to both main surfaces of a glass substrate. Fine irregularities formed on both main surfaces are removed.

  In the outer periphery / inner periphery polishing step S15, mirror polishing is performed on the outer peripheral end surface and the inner peripheral end surface of the glass substrate using a brush. As the abrasive grains, for example, a slurry containing cerium oxide abrasive grains is used. In the first polishing step S16, both main surfaces of the glass substrate are polished using a double-side polishing apparatus having a planetary gear mechanism. As the abrasive, for example, cerium oxide abrasive grains having an average particle diameter of about 1 μm are used. In the first and second lapping steps (S12, S14), scratches and warpage remaining on both main surfaces are corrected.

  In the chemical strengthening step S17, compressive stress layers are formed on both main surfaces of the glass substrate. A mixed solution of potassium nitrate (70%) and sodium nitrate (30%) is heated to 300 ° C., and the glass substrate is immersed in the mixed solution for about 30 minutes. A compressive stress layer is formed, and both main surfaces and both end surfaces of the glass substrate are strengthened.

  In the second polishing step S18, precision polishing is performed on both main surfaces of the glass substrate using a double-side polishing apparatus having a planetary gear mechanism. As the abrasive, for example, colloidal silica having an average particle diameter of about 20 nm is used. The micro-defects remaining on both main surfaces are eliminated, and both main surfaces are finished in a mirror shape. Fine warpage is also eliminated, and both main surfaces have a desired flatness. Further details of the second polishing step S18 will be described later with reference to FIG.

  In the final cleaning step S19, both the main surface and both end surfaces of the glass substrate are cleaned, and then the glass substrate is appropriately dried. The manufacturing method of the glass substrate for information recording media in this Embodiment is comprised as mentioned above. The glass substrate 1G shown in FIG. 1 is obtained by using this glass substrate manufacturing method. As described above, the magnetic disk 1 shown in FIG. 2 is obtained by forming the magnetic thin film layer on the glass substrate 1G.

(Second polishing step S18)
With reference to FIGS. 4-18, the detail of 2nd polishing process S18 is demonstrated. As shown in FIG. 4, the second polishing step S18 includes steps S181 to S187. As described above, in the second polishing step S18, precision polishing is performed on both main surfaces of the glass substrate using a double-side polishing apparatus having a planetary gear mechanism.

  The double-side polishing apparatus 100 used in the second polishing step S18 will be described with reference to FIGS. FIG. 5 is a side view showing the double-side polishing apparatus 100. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. FIG. 7 is an enlarged view showing a region surrounded by the line VII in FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG.

  As shown in FIG. 5, the double-side polishing apparatus 100 includes an upper surface plate 20, an upper polishing pad 21, a lower surface plate 30, and a lower polishing pad 31. The upper surface plate 20 and the lower surface plate 30 have a cylindrical shape. The upper polishing pad 21 is mounted on the lower surface on the side (glass substrate side) facing the lower surface plate 30 of the upper surface plate 20. The lower polishing pad 31 is mounted on the upper surface on the side (glass substrate side) facing the upper surface plate 20 of the lower surface plate 30. The lower surface of the upper surface plate 20 and the upper surface of the lower surface plate 30 are parallel to each other and rotate in opposite directions.

  The upper polishing pad 21 and the lower polishing pad 31 are processed members for polishing both main surfaces of the glass substrate. For example, a polyurethane suede pad is used as the upper polishing pad 21 and the lower polishing pad 31. A surface of the upper polishing pad 21 facing the lower surface plate 30 forms an upper polishing surface 22. The surface of the lower polishing pad 31 facing the upper surface plate 20 forms a lower polishing surface 32.

  As shown in FIGS. 6 and 7, a plurality of polishing carriers 60 having a disk shape are disposed on the lower polishing surface 32 (see FIG. 6). The carrier 60 includes a holding portion 61 (see FIG. 7) having a plurality of circular holes, and a plurality of meshing teeth 62 are provided on the outer periphery of the carrier 60. The thickness of the carrier 60 is, for example, 650 μm.

  The glass substrate 1G is disposed in a circular hole provided in the holding unit 61 (see FIG. 7). The thickness of the glass substrate 1G is, for example, 810 μm. A sun gear 40 is provided at the center of the lower surface plate 30 (see FIG. 6). An internal gear 50 is provided coaxially with the sun gear 40 at the periphery of the lower surface plate 30 (see FIG. 6). The sun gear 40 and the internal gear 50 are thicker than the carrier 60 in a direction parallel to the rotation axis of the sun gear 40.

  In a state where the carrier 60 is disposed between the sun gear 40 and the internal gear 50, the meshing teeth 62 of the carrier 60 mesh with both the tooth surface 42 of the sun gear 40 and the tooth surface 52 of the internal gear 50. The carrier 60 is rotated using the sun gear 40 and the internal gear 50. In the present embodiment, when the sun gear 40 is driven to rotate, the carrier 60 revolves around the sun gear 40 while rotating.

  As shown in FIG. 8, the back main surface of the glass substrate 1 </ b> G held by the carrier 60 is in contact with the lower polishing surface 32 of the lower polishing pad 31. In this state, the upper surface plate 20 moves downward along the vertical direction toward the lower surface plate 30 (see the white arrow). Thereafter, the upper polishing surface 22 of the upper polishing pad 21 comes into contact with the front main surface of the glass substrate 1 </ b> G held by the carrier 60.

  As shown in FIG. 9, the glass substrate 1 </ b> G is sandwiched between the upper polishing pad 21 and the lower polishing pad 31. The upper surface plate 20 and the lower surface plate 30 apply a predetermined stress to the glass substrate 1G in the thickness direction. Both main surfaces of the glass substrate 1G are pressed against the upper polishing surface 22 and the lower polishing surface 32.

  In this state, while supplying a polishing liquid such as colloidal silica, the upper polishing surface 22 moves relative to the front main surface of the glass substrate 1G, and the lower polishing surface 32 moves relative to the back main surface of the glass substrate 1G. Moving. When the upper polishing surface 22 is in sliding contact with the front main surface of the glass substrate 1G, the front main surface of the glass substrate 1G is polished. When the lower polishing surface 32 is in sliding contact with the back main surface of the glass substrate 1G, the back main surface of the glass substrate 1G is polished. Both main surfaces of the glass substrate are polished simultaneously.

  With reference to FIG. 4 again, steps S181 to S187 will be specifically described. In the first setting step S181, a plurality of glass substrates 1G (see FIG. 6) are prepared and fixed to the carrier 60. The carrier 60 holding the plurality of glass substrates 1G is disposed between the sun gear 40 and the internal gear 50. Without being limited to this configuration, a plurality of glass substrates 1G may be disposed in the circular holes of the carrier 60 that are already disposed between the sun gear 40 and the internal gear 50. In this case, the carrier 60 does not need to fix the glass substrate 1G, and a clearance may be secured between the glass substrate 1G and the inner peripheral surface of the circular hole.

  FIG. 10 is a perspective view showing a state in which the meshing teeth 62 of the carrier 60 are meshed with the tooth surfaces 52 of the internal gear 50. In this state, the tooth tip 53 of the tooth surface 52 of the internal gear 50 has a flat surface shape with a very gentle cylindrical surface, and is along a direction parallel to the rotation axis of the sun gear 40 (see FIG. 7). It extends. FIG. 11 is a diagram schematically showing a state when the tooth surface 52 of the internal gear 50 is viewed from the direction of the arrow XI in FIG. 10 (a diagram in which the tooth surface 52 is developed in the circumferential direction). The meshing state shown in FIGS. 10 and 11 is the same between the sun gear 40 (see FIG. 7) and the carrier 60. The tooth tip of the tooth surface 42 of the sun gear 40 also has a flat surface shape and extends along a direction parallel to the rotation axis of the sun gear 40 (see FIG. 7).

  In the first sliding step S182 (see FIG. 4), the glass substrate 1G (FIG. 8) is used with the meshing teeth 62 of the carrier 60 meshed with both the tooth surface 42 of the sun gear 40 and the tooth surface 52 of the internal gear 50. 9) is sandwiched between the upper polishing pad 21 and the lower polishing pad 31. The carrier 60 is rotated using the sun gear 40 and the internal gear 50. Both main surfaces of the glass substrate 1G are brought into sliding contact with the upper polishing surface 22 of the upper polishing pad 21 and the lower polishing surface 32 of the lower polishing pad 31. Both main surfaces of the glass substrate 1G are polished.

  In the extraction step S183 (see FIG. 4), the glass substrate 1G is extracted from the double-side polishing apparatus 100. After completion of the first sliding step S182, the glass substrate 1G may be held by the carrier 60, may be attached to the upper polishing surface 22 of the upper polishing pad 21, or the lower polishing pad 31. In some cases, it is attached to the lower polished surface 32. When the glass substrate 1G is removed from the double-side polishing apparatus 100, the method includes removing the glass substrate 1G from the carrier 60, the upper polishing pad 21, or the lower polishing pad 31.

  When other glass substrates 1G to be subjected to the second polishing step S18 (see FIG. 4) remain, in other words, other glass substrates 1G subjected to the glass melting step S10 to the chemical strengthening step S17 In the case of remaining, the first setting step S181, the first sliding step S182, and the removing step S183 may be repeatedly performed on the glass substrates 1G.

  FIG. 12 shows the first setting step S181, the first sliding step S182, and the removing step after the first setting step S181, the first sliding step S182, and the removing step S183 are repeated a plurality of times or once. It is a perspective view which shows the tooth surface 52 of the internal gear 50 after S183 was performed. FIG. 13 is a diagram schematically showing a state when the tooth surface 52 of the internal gear 50 is viewed from the direction of arrow XIII in FIG. 12 (a diagram in which the tooth surface 52 is developed in the circumferential direction).

  As shown in FIGS. 12 and 13, the carrier 60 rotates in a state where the meshing teeth 62 of the carrier 60 are engaged with the tooth surface 52 of the internal gear 50 in the first sliding step S <b> 182, so that the tooth surface 52 A concave groove 70 is formed. The concave groove 70 is formed by wear of the tooth surface 52, and has a shape that is recessed from the tooth tip 53 of the tooth surface 52 toward the radially outer side of the internal gear 50. When the internal gear 50 is used repeatedly, the groove 70 gradually grows.

  Referring to FIG. 14, depending on the use state of internal gear 50, concave groove 70 may grow to tooth root 54 of tooth surface 52. If the internal gear 50 is continuously used, the groove 70 further grows. Referring to FIG. 15, when the internal gear 50 is further used, the plurality of concave grooves 70 (see FIG. 14) are connected to form one continuous annular concave groove 71. In the direction parallel to the rotation axis of the sun gear 40 (the vertical direction in FIG. 15), the width dimension H71 of the annular groove 71 is substantially equal to the thickness value of the meshing teeth 62 of the carrier 60. In this embodiment, an example in which the groove 70 grows from the tooth tip side of the tooth surface 52 is shown, but the correlation between the shape of the meshing tooth 62 of the carrier 60 and the shape of the tooth surface 52 of the internal gear 50 is shown. Depending on the case, the groove 70 may grow from a portion on the side surface side of the tooth surface 52 or a tooth root of the tooth surface 52.

  Referring to FIG. 16, when the internal gear 50 is further used, the annular groove 71 grows to form the annular groove 72. The annular groove 72 has a shape that undulates vertically in a direction parallel to the rotation axis of the sun gear 40. A width dimension H72 of the annular groove 72 is larger than a width dimension H71 of the annular groove 71 (see FIG. 15). When this state is reached, the tooth surface 52 of the internal gear 50 no longer forms a deteriorated state, and the tooth surface 52 of the internal gear 50 becomes difficult to properly mesh with the meshing teeth 62 of the carrier 60. The same applies to the sun gear 40 as described with reference to FIGS. A concave groove 73 (see FIG. 17) is formed in the tooth surface 42 of the sun gear 40.

  As shown in FIG. 16, the carrier 60 may mesh with the sun gear 40 and the internal gear 50 while being inclined with respect to a plane orthogonal to the rotation axis of the sun gear 40. When the glass substrate 1 </ b> G is polished with the carrier 60 tilted, the upper polishing surface 22 of the upper polishing pad 21 and the lower polishing surface 32 of the lower polishing pad 31 are damaged by contact with the tilted carrier 60. When polishing is performed using the damaged upper polishing pad 21 and lower polishing pad 31, fine pits or deposits are formed as defects on both main surfaces of the glass substrate 1G. This defect induces read / write errors and head crashes when the glass substrate 1G is used as the magnetic disk 1.

(Height change process S184)
In the second polishing step S18 of the present embodiment, a height changing step S184 (see FIG. 4) is performed to prevent the carrier 60 from tilting. The height changing step S184 is performed after a predetermined number of times of the first sliding step S182, after the total polishing time in the first sliding step S182 reaches a predetermined time (for example, 50 hours), or for a certain period of time. It should be done after (e.g. 1 month) has passed. The height changing step S184 is performed before a second sliding step S186 described later.

  Referring to FIG. 17, in the height changing step S184 of the present embodiment, a spacer member 46 is provided between the sun gear 40 and the member 48 that supports the sun gear 40 to support the internal gear 50 and the internal gear 50. A spacer member 56 is provided between the first member 58 and the second member 58. The sun gear 40 and the internal gear 50 are in a so-called raised state. A dotted line in FIG. 17 indicates a position where the sun gear 40 and the internal gear 50 are arranged before being raised.

  The position of the groove 73 formed in the tooth tip 43 of the sun gear 40 is changed upward in a direction parallel to the rotation axis of the sun gear 40. The position of the groove 70 formed in the tooth tip 53 of the internal gear 50 is also changed upward in a direction parallel to the rotation axis of the sun gear 40.

  A virtual plane 90 orthogonal to the axial direction (rotation axis) of the sun gear 40 is drawn, and a dimension from the virtual plane 90 to an arbitrary position in the axial direction is defined as a height. The sun gear 40 having the height position H40 before raising the height has a height position H41 after raising the height. The internal gear 50 having the height position H50 before the raising is provided with the height position H51 after the raising.

  That is, when a direction parallel to the axial direction of the sun gear 40 is referred to as a height direction, a portion of the tooth surface 42 of the sun gear 40 where the carrier 60 is engaged in the first sliding step S182 is defined as a first location A. If the portion of the tooth surface 42 of the sun gear 40 that the carrier 60 should mesh with in the second sliding step S186 is the second location B, the height position of the second location B within the tooth surface 42 of the sun gear 40 Is a position different from the position in the height direction of the first location A within the tooth surface 42 of the sun gear 40. The position in the height direction of the second location B within the tooth surface 42 of the sun gear 40 is subjected to a height changing step S184 from the position in the height direction of the first location A within the tooth surface 42 of the sun gear 40. Has been changed by.

  Similarly for the internal gear 50, the portion of the tooth surface 52 of the internal gear 50 where the carrier 60 is engaged in the first sliding step S182 is defined as the third location C, and the tooth surface 52 of the internal gear 50 includes: If the portion where the carrier 60 should mesh in the second sliding step S186 is the fourth location D, the position in the height direction of the fourth location D within the tooth surface 52 of the internal gear 50 is the tooth surface 52 of the internal gear 50. It is a position different from the position of the third location C in the height direction. The position in the height direction of the fourth location D within the tooth surface 52 of the internal gear 50 is the height change step S184 from the position in the height direction of the third location C within the tooth surface 52 of the internal gear 50. Has changed by going through.

  The timing at which the spacer member 46 is provided below the sun gear 40 and the timing at which the spacer member 56 is provided below the internal gear 50 are preferably matched. These timings may be optimized as appropriate according to the growth condition of the groove 73 formed in the sun gear 40 and the growth condition of the groove 70 formed in the internal gear 50.

  For the sun gear 40, the depth D73 of the groove 73 formed in the sun gear 40 is preferably 0.14 or more (for example, the depth D73 is 0.6 mm or more) as a percentage of the outer diameter of the carrier 60. At that time, a spacer member 46 may be provided below the sun gear 40. The depth D73 of the concave groove 73 referred to here is a distance from the tooth tip 43 of the tooth surface 42 to a portion of the concave groove 73 located on the innermost side in the radial direction of the sun gear 40.

  Similarly, for the internal gear 50, the depth D70 of the concave groove 70 formed in the internal gear 50 is preferably 0.14 or more as a percentage of the outer diameter of the carrier 60 (for example, the depth D70 is 0.6 mm). At this point, the spacer member 56 may be provided below the internal gear 50. The depth D70 of the concave groove 70 referred to here is a distance from the tooth tip 53 of the tooth surface 52 to a portion of the concave groove 70 positioned on the outermost side in the radial direction of the internal gear 50.

  Referring to FIG. 18, after the height changing step S184 is completed, a second setting step S185 is performed. In the second setting step S185, another glass substrate 1H is fixed to a carrier 60 as one carrier. Here, instead of using the carrier 60, another carrier in an unused state may be used as one carrier. This is because the meshing teeth 62 of the carrier 60 may be deteriorated after the first setting step S181 is repeatedly performed.

  The other glass substrate 1H mentioned here means a glass substrate on which the first sliding step S182 has not been performed, and is different from the glass substrate 1G (see FIG. 9) on which the first sliding step S182 has been performed. It is. The other carrier in this unused state means a so-called new carrier that has never been used for polishing in the double-side polishing apparatus 100.

  The carrier 60 holding another glass substrate 1H is disposed between the raised sun gear 40 and the raised internal gear 50. Without being limited to this configuration, a plurality of other glass substrates 1H may be disposed on the carrier 60 that is already disposed between the raised sun gear 40 and the raised internal gear 50.

  Of the tooth surface 42 (tooth tip 43) of the sun gear 40, the portion (second location B) where the meshing teeth 62 of the carrier 60 mesh in the second sliding step S186 described below has a flat surface shape. It extends along a direction parallel to the rotation axis of the sun gear 40. Similarly, in the tooth surface 52 (tooth tip 53) of the internal gear 50, the portion (fourth place D) where the meshing teeth 62 of the carrier 60 mesh in the second sliding step S186 described below is a flat surface shape. And extends along a direction parallel to the rotation axis of the sun gear 40.

  Also in the second sliding step S186 (see FIG. 4), the glass substrate 1H (FIG. 18) is used with the meshing teeth 62 of the carrier 60 engaged with both the tooth surface 42 of the sun gear 40 and the tooth surface 52 of the internal gear 50. Is sandwiched between the upper polishing pad 21 and the lower polishing pad 31. The carrier 60 is rotated using the sun gear 40 and the internal gear 50. Both main surfaces of the glass substrate 1H are brought into sliding contact with the upper polishing surface 22 of the upper polishing pad 21 and the lower polishing surface 32 of the lower polishing pad 31. Both main surfaces of the glass substrate 1H are polished.

  In the extraction step S187 (see FIG. 4), the glass substrate 1H is extracted from the double-side polishing apparatus 100. After completion of the second sliding step S186, the glass substrate 1H may be held by the carrier 60, may be attached to the upper polishing surface 22 of the upper polishing pad 21, or the lower polishing pad 31. In some cases, it is attached to the lower polished surface 32. The removal of the glass substrate 1H from the double-side polishing apparatus 100 includes removing the glass substrate 1H from the carrier 60, the upper polishing pad 21 or the lower polishing pad 31.

  When other glass substrates 1H to be subjected to the second polishing step S18 (see FIG. 4) remain, in other words, other glass substrates 1H that have been subjected to the glass melting step S10 to the chemical strengthening step S17. In the case where the second substrate remains, the second setting step S185, the second sliding step S186, and the removing step S187 are preferably performed repeatedly on the glass substrates 1H.

  Of the tooth surfaces 42 and 52 of the sun gear 40 and the internal gear 50, the portions (locations A and C) used in the second sliding step S186 have no or almost no concave grooves. It is possible to effectively suppress the tilt of the carrier 60 during the rotation. There is no or almost no scratch on the upper polishing surface 22 of the upper polishing pad 21 and the lower polishing surface 32 of the lower polishing pad 31, and fine pits or deposits are formed as defects on both main surfaces of the glass substrate 1H. This is also effectively suppressed. Therefore, the glass substrate for information recording media manufactured by the manufacturing method and manufacturing apparatus for the information recording medium glass substrate in the present embodiment has higher surface quality.

[Embodiment 2]
Referring to FIG. 19, in the height changing step S184 (see FIG. 4), the sun gear 40 and / or the internal gear 50 may be turned upside down with respect to the axial direction of the sun gear 40 instead of using the spacer member. . The upside down operation may be further performed using a spacer member.

  Even in this configuration, when the direction parallel to the axial direction of the sun gear 40 is referred to as the height direction, the portion of the tooth surface 42 of the sun gear 40 where the carrier 60 is engaged in the first sliding step S182 is the first. If the portion A and the portion of the tooth surface 42 of the sun gear 40 that the carrier 60 should mesh with in the second sliding step S186 is the second portion B, the height of the second portion B in the tooth surface 42 of the sun gear 40 The position in the direction is a position different from the position in the height direction of the first location A in the tooth surface 42 of the sun gear 40. The position in the height direction of the second location B within the tooth surface 42 of the sun gear 40 is subjected to a height changing step S184 from the position in the height direction of the first location A within the tooth surface 42 of the sun gear 40. Has been changed by.

  Similarly for the internal gear 50, the portion of the tooth surface 52 of the internal gear 50 where the carrier 60 is engaged in the first sliding step S182 is defined as the third location C, and the tooth surface 52 of the internal gear 50 includes: If the portion where the carrier 60 should mesh in the second sliding step S186 is the fourth location D, the position in the height direction of the fourth location D within the tooth surface 52 of the internal gear 50 is the tooth surface 52 of the internal gear 50. It is a position different from the position of the third location C in the height direction. The position in the height direction of the fourth location D within the tooth surface 52 of the internal gear 50 is the height change step S184 from the position in the height direction of the third location C within the tooth surface 52 of the internal gear 50. Has changed by going through.

[Embodiment 3]
The second polishing step S18A shown in FIG. 20 further includes a measurement step S188b. The measurement step S188b is performed after the first sliding step S182 and before the height changing step S184. After it is determined in step S188a that the conditions for moving to the measurement process are satisfied, in the measurement process S188b, a concave groove formed in the tooth surface 42 of the sun gear 40 and / or a tooth surface 52 of the internal gear 50 is formed. The depth of the recessed groove formed is measured. As described in the first embodiment, these concave grooves mean that the meshing teeth 62 of the carrier 60 mesh with the tooth surfaces 42 and 52 of both the sun gear 40 and the internal gear 50 in the first sliding step S182. In this state, the carrier 60 is rotated.

  In the measurement step S188b, after a predetermined number of times of the first sliding step S182 is performed, the total polishing time in the first sliding step S182 reaches a predetermined time, or a certain period (such as one month) elapses. It is good to be done after. In the present embodiment, after measurement step S188b, it is determined whether or not the depth of the groove is 0.14 or more (as an example, 0.6 mm or more) as a percentage with respect to the outer diameter of carrier 60 (step). S189). When the depth D73 of the concave groove 73 formed in the sun gear 40 is determined to be 0.14 or more with respect to the outer diameter of the carrier 60, and the depth of the concave groove 70 formed in the internal gear 50 The height changing step is performed when the earlier one of the time points at which the height D70 is determined to be 0.14 or more (0.6 mm or more as an example) with respect to the outer diameter of the carrier 60, whichever comes first. S184 is performed. The first setting step S181 and the first sliding step S182 until the depth of the groove measured in the measuring step S188b is 0.14 (0.6 mm or more as an example) as a percentage with respect to the outer diameter of the carrier 60. And extraction process S183 is performed repeatedly.

  By carrying out the measurement step S188b and periodically and actively inspecting the depth of the groove, the information recording medium glass substrate manufactured by the method and apparatus for manufacturing the information recording medium glass substrate is more It will have high surface quality.

[Experimental example]
With reference to FIG. 21 and FIG. 22, the experiment example performed in relation to each above-mentioned embodiment (2nd polishing process S18) is demonstrated. The experimental examples included examples and comparative examples. The example has the above-described first sliding step, measuring step, height changing step, and second sliding step. The comparative example has the first sliding step described above.

  In each example, a carrier having a pitch circle diameter of about 423 mm and a thickness of 650 μm and a glass substrate having an outer diameter of 65 mm and a thickness of 810 μm were prepared. In one first sliding step, five carriers are used, and each carrier holds 20 glass substrates, and a total of 100 glass substrates are simultaneously polished. did.

  As shown in FIG. 21, in order to suppress the time-dependent wear generated in the polishing pad from affecting the experimental results, the polishing pad attached on both the upper and lower surface plates was replaced. The polishing pad was affixed with a new product at an initial time, and the timing for exchanging the polishing pad was set at every 180 hours from the initial time when the experiment was started. A 16B double-side polishing machine manufactured by Hamai Sangyo Co., Ltd. was used as the polishing apparatus.

  Yield was measured for 200 pieces of the 100 glass substrates obtained every time the first sliding step was performed. Yield is measured by measuring defects on both main surfaces of the cleaned glass substrate to discriminate between good and defective products. SSI-640 (surface inspection device using He-Ne laser light source Manufactured by System Seiko Co., Ltd.). Further, the details of the defect were confirmed with a Candela (registered trademark) 6300 (surface inspection apparatus, manufactured by KLA-Tencor) for the substrate determined to be defective by SSI-640.

  The measurement process was performed and the depth of the groove formed in the tooth surface of each gear was measured. The measurement timing was 90 hours after the initial processing start time for the polishing processing total processing time as the first timing, and thereafter, the polishing processing total processing time was set every 180 hours. In the example, since it was confirmed that the depth of the concave groove exceeded 0.6 mm when the total processing time of the polishing process reached about 810 hours, the height changing step was performed at this point. Thereafter, in the example, the second sliding step was performed.

  When the height changing step was performed in the example, the carrier was also replaced with another carrier that was not used. Replacement with another carrier in an unused state was performed in both the example and the comparative example, and the replacement timing was the same in the example and the comparative example.

  As shown in FIG. 22, for both the example and the comparative example, it can be seen that the yield of the glass substrate obtained each time the first sliding step is performed gradually decreases as the total processing time becomes longer. It was. On the other hand, in the examples, it was found that the yield of the glass substrate obtained in the second sliding step was sufficiently recovered compared with that in the comparative example by performing the height changing step. It was found that the decrease in yield in the comparative example was mainly caused by pits.

  Therefore, it was found that the glass substrate for information recording medium manufactured by the method and apparatus for manufacturing the glass substrate for information recording medium in each of the above embodiments has higher surface quality.

  As mentioned above, although each embodiment and Example based on this invention were described, each embodiment and Example disclosed this time are illustrations in all the points, Comprising: It is not restrictive. The technical scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Magnetic disk, 1G, 1H glass substrate, 11 holes, 12 Outer peripheral end surface, 13 Inner peripheral end surface, 13a, 13b Chamfer surface, 14 Front main surface, 15 Back main surface, 16 Magnetic thin film layer, 20 Upper surface plate, 21 Upper Polishing pad, 22 Upper polishing surface, 30 Lower surface plate, 31 Lower polishing pad, 32 Lower polishing surface, 40 Sun gear, 42,52 Tooth surface, 43,53 Tooth tip, 46,56 Spacer member, 48,58 member, 50 Internal Lugear, 54 tooth base, 60 carrier, 61 holding part, 62 meshing tooth, 70, 73 concave groove, 71, 72 annular concave groove, 90 virtual plane, 100 double-side polishing device, A 1st place, B 2nd place, C 3rd place, D 4th place, D70, D73 depth, H40, H41, H50, H51 position, H71, H72 width dimension, S10 glass melting step, S11 Press forming step, S12 first lapping step, S13 coring step, S14 second lapping step, S15 outer / inner peripheral polishing step, S16 first polishing step, S17 chemical strengthening step, S18, S18A second polishing step, S19 final Cleaning step, S181 first setting step, S182 first sliding step, S183, S187 removal step, S184 height changing step, S185 second setting step, S186 second sliding step, S188a step, S188b measuring step.

Claims (5)

A first setting step of disposing a polishing carrier and a glass substrate on a surface plate of a double-side polishing machine;
The carrier is rotated using the sun gear and the internal gear while the outer periphery of the carrier is engaged with the tooth surfaces of both the sun gear and the internal gear, and the glass substrate is brought into sliding contact with the polishing surface of the polishing pad. A first sliding step for polishing the surface of the glass substrate;
A second setting step of arranging one of the carrier and the other carrier and another glass substrate on the surface plate of the double-side polishing machine;
The one carrier is rotated using the sun gear and the internal gear in a state where the outer circumference of the one carrier is engaged with the tooth surfaces of both the sun gear and the internal gear, and the polishing surface of the polishing pad is rotated. A second sliding step in which the other glass substrate is slidably contacted to polish the surface of the other glass substrate;
When the position in the direction parallel to the axial direction of the sun gear is referred to as height after the first sliding step and before the second sliding step, the tooth surface of the sun gear The portion where the carrier meshes in the first sliding step is defined as a first location, and the portion of the tooth surface of the sun gear where the one carrier is meshed in the second sliding step is a second location. A portion where the carrier meshes in the first sliding step of the tooth surface of the internal gear is a third location, and in the second sliding step of the tooth surface of the internal gear, If the portion where one carrier should mesh is the fourth location, the height position of the second location in the tooth surface of the sun gear is different from the first location, and the teeth of the internal gear E Bei making the position in the height direction of the fourth point in the inner different from the third location, the height changing step having at least one of, a,
In the height changing step, the sun gear and the internal gear are turned upside down in the axial direction.
A method for producing a glass substrate for an information recording medium. Measurement that is performed after the first sliding step and before the height changing step, and measures the depth of the concave surface formed on the tooth surface of the sun gear and / or the tooth surface of the internal gear. A further process,
The concave groove is formed by rotating the carrier in a state where the outer periphery of the carrier meshes with the tooth surfaces of both the sun gear and the internal gear in the first sliding step,
The first setting step and the first sliding step are repeated until the depth of the concave groove measured in the measurement step is 0.14 or more as a percentage with respect to the outer diameter of the carrier.
The manufacturing method of the glass substrate for information recording media of Claim 1. A first setting step of disposing a polishing carrier and a glass substrate on a surface plate of a double-side polishing machine;
The carrier is rotated using the sun gear and the internal gear while the outer periphery of the carrier is engaged with the tooth surfaces of both the sun gear and the internal gear, and the glass substrate is brought into sliding contact with the polishing surface of the polishing pad. A first sliding step for polishing the surface of the glass substrate;
A second setting step of arranging one of the carrier and the other carrier and another glass substrate on the surface plate of the double-side polishing machine;
The one carrier is rotated using the sun gear and the internal gear in a state where the outer circumference of the one carrier is engaged with the tooth surfaces of both the sun gear and the internal gear, and the polishing surface of the polishing pad is rotated. A second sliding step in which the other glass substrate is slidably contacted to polish the surface of the other glass substrate;
When the position in the direction parallel to the axial direction of the sun gear is referred to as height after the first sliding step and before the second sliding step, the tooth surface of the sun gear The portion where the carrier meshes in the first sliding step is defined as a first location, and the portion of the tooth surface of the sun gear where the one carrier is meshed in the second sliding step is a second location. A portion where the carrier meshes in the first sliding step of the tooth surface of the internal gear is a third location, and in the second sliding step of the tooth surface of the internal gear, If the portion where one carrier should mesh is the fourth location, the height position of the second location in the tooth surface of the sun gear is different from the first location, and the teeth of the internal gear Causing the position in the height direction of the fourth point in the inner different from the third location, and a height changing step having at least one of,
Measurement that is performed after the first sliding step and before the height changing step, and measures the depth of the concave surface formed on the tooth surface of the sun gear and / or the tooth surface of the internal gear. A further process,
The concave groove is formed by rotating the carrier in a state where the outer periphery of the carrier meshes with the tooth surfaces of both the sun gear and the internal gear in the first sliding step,
The first setting step and the first sliding step are repeated until the depth of the concave groove measured in the measurement step is 0.14 or more as a percentage with respect to the outer diameter of the carrier.
A method for producing a glass substrate for an information recording medium. In the height changing step, a spacer member is provided between the sun gear and the member that supports the sun gear, and between the internal gear and the member that supports the internal gear, respectively.
The manufacturing method of the glass substrate for information recording media of Claim 3. In the second setting step and the second sliding step immediately after the height changing step, the other carrier in an unused state is used as the one carrier.
The manufacturing method of the glass substrate for information recording media in any one of Claim 1 to 4.

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