WO2013146131A1 - Manufacturing method for glass substrate for information recording medium, and information recording medium - Google Patents

Manufacturing method for glass substrate for information recording medium, and information recording medium Download PDF

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Publication number
WO2013146131A1
WO2013146131A1 PCT/JP2013/056078 JP2013056078W WO2013146131A1 WO 2013146131 A1 WO2013146131 A1 WO 2013146131A1 JP 2013056078 W JP2013056078 W JP 2013056078W WO 2013146131 A1 WO2013146131 A1 WO 2013146131A1
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WIPO (PCT)
Prior art keywords
glass substrate
information recording
polishing
recording medium
carrier
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PCT/JP2013/056078
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French (fr)
Japanese (ja)
Inventor
小松　隆史
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コニカミノルタ株式会社
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Publication of WO2013146131A1 publication Critical patent/WO2013146131A1/en

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
    • G11B5/8404—Processes or apparatus specially adapted for manufacturing record carriers manufacturing base layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • B24B37/27—Work carriers
    • B24B37/28—Work carriers for double side lapping of plane surfaces

Definitions

  • the present invention relates to a method for manufacturing a glass substrate for information recording medium and an information recording medium, and in particular, includes a method for manufacturing a glass substrate for information recording medium used for manufacturing an information recording medium, and the glass substrate for information recording medium.
  • the present invention relates to an information recording medium.
  • An information recording medium such as a magnetic disk is mounted as a hard disk on a computer or the like.
  • An information recording medium is manufactured by forming a magnetic thin film layer including a recording layer using properties such as magnetism, light, or magnetomagnetism on the surface of a substrate. As the recording layer is magnetized by the magnetic head, predetermined information is recorded on the information recording medium.
  • the recording density of information recording media is improving year by year. Accordingly, high quality is required for the quality of substrates used for information recording media.
  • an aluminum substrate has been used as a substrate for an information recording medium.
  • the recording density is improved, it is gradually being replaced by a glass substrate that is superior in smoothness and strength of the substrate surface as compared with an aluminum substrate.
  • the method for producing a glass substrate for an information recording medium has a grinding process / polishing process for ensuring high surface shape accuracy.
  • a grinding process / polishing process for ensuring high surface shape accuracy.
  • two or more stages of grinding / polishing processes in which slurry and grinding / polishing pads having different processing capabilities are effectively combined are applied.
  • Patent Document 1 discloses a conventional technology relating to glass substrate manufacturing.
  • the middle band area is substantially the carrier and the glass substrate (workpiece).
  • the typical transit time is longer than that of the outer peripheral region and the inner peripheral region.
  • a difference in wear state of the polishing pad (uneven wear) occurs between the outer peripheral region and the inner peripheral region and the middle belt region. Due to this uneven wear, there was variation in the flatness of the glass substrate.
  • An object of the present invention is to provide a method for manufacturing a glass substrate for an information recording medium and an information recording medium that can suppress the occurrence of a difference (partial wear) in the wear state of the pad.
  • the method for manufacturing a glass substrate for information recording medium is a method for manufacturing a glass substrate for information recording medium in which a magnetic thin film layer is formed on the main surface of a circular disk-shaped glass substrate, comprising a planetary gear mechanism. And a surface polishing step of polishing the main surface of the glass substrate while supplying an abrasive.
  • the double-side polishing apparatus is located on the upper side of the glass substrate, has an upper surface plate having an upper polishing pad on the glass substrate side, and is located on the lower side of the glass substrate, and has a lower polishing pad on the glass substrate side.
  • a disk-shaped carrier that is provided with a plurality of through-holding holes for holding the glass substrate and is sandwiched between the upper polishing pad and the lower polishing pad and that performs a predetermined rotational movement by the planetary gear mechanism.
  • the carrier has a glass substrate non-holding region that does not hold the glass substrate, and the glass substrate non-holding region is surrounded by a radius Dmm from the center position of the carrier when the diameter of the glass substrate is Dmm. Includes a circular area.
  • the center of the through-holding hole is not provided in a circular region surrounded by a radius Dmm from the center position of the carrier.
  • the glass substrate non-holding region has an auxiliary through hole that cannot hold the glass substrate.
  • the glass substrate obtained by the manufacturing method of the glass substrate for information recording media described in any of the above, and the magnetic thin film layer formed on the main surface of the glass substrate Prepare.
  • the present invention in the polishing process using the double-side polishing apparatus, it is possible to suppress the occurrence of a difference in the wear state of the polishing pad between the outer peripheral region and the inner peripheral region and the middle belt region of the polishing pad. Further, it is possible to provide a method for manufacturing a glass substrate for an information recording medium and an information recording medium.
  • FIG. 1 is a perspective view showing a glass substrate 1 used for a magnetic disk 10 (see FIG. 2).
  • FIG. 2 is a perspective view showing a magnetic disk 10 provided with a glass substrate 1 as an information recording medium.
  • a glass substrate 1 (glass substrate for information recording medium) used for a magnetic disk 10 has an annular disk shape with a hole 1H formed in the center.
  • the circular disk-shaped glass substrate 1 has a front main surface 1A, a back main surface 1B, an inner peripheral end surface 1C, and an outer peripheral end surface 1D.
  • the size of the glass substrate 1 is not particularly limited, and is, for example, 0.8 inch, 1.0 inch, 1.8 inch, 2.5 inch, or 3.5 inch outer diameter.
  • the thickness of the glass substrate 1 is, for example, 0.30 mm to 2.2 mm from the viewpoint of preventing breakage.
  • the outer diameter is about 65 mm
  • the inner diameter is about 20 mm
  • the thickness is about 0.8 mm.
  • the thickness of the glass substrate 1 is a value calculated by averaging the values measured at a plurality of arbitrary points that are point-symmetric on the glass substrate 1.
  • a magnetic film is formed on the front main surface 1A of the glass substrate 1 to form a magnetic thin film layer 2 including a magnetic recording layer.
  • the magnetic thin film layer 2 is formed only on the front main surface 1A, but the magnetic thin film layer 2 may also be formed on the back main surface 1B.
  • the magnetic thin film layer 2 is formed by spin-coating a thermosetting resin in which magnetic particles are dispersed on the front main surface 1A of the glass substrate 1 (spin coating method).
  • the magnetic thin film layer 2 may be formed on the front main surface 1A of the glass substrate 1 by a sputtering method, an electroless plating method, or the like.
  • the film thickness of the magnetic thin film layer 2 formed on the front main surface 1A of the glass substrate 1 is about 0.3 ⁇ m to about 1.2 ⁇ m in the case of the spin coating method, and about 0.04 ⁇ m to about 0.00 in the case of the sputtering method. In the case of electroless plating, the thickness is about 0.05 ⁇ m to about 0.1 ⁇ m. From the viewpoint of thinning and high density, the magnetic thin film layer 2 is preferably formed by sputtering or electroless plating.
  • the magnetic material used for the magnetic thin film layer 2 is not particularly limited, and a conventionally known material can be used. However, in order to obtain a high coercive force, Co having high crystal anisotropy is basically used for the purpose of adjusting the residual magnetic flux density. A Co-based alloy to which Ni or Cr is added is suitable. Further, as a magnetic layer material suitable for heat-assisted recording, an FePt-based material may be used.
  • a lubricant may be thinly coated on the surface of the magnetic thin film layer 2 in order to improve the sliding of the magnetic recording head.
  • the lubricant include those obtained by diluting perfluoropolyether (PFPE), which is a liquid lubricant, with a solvent such as Freon.
  • an underlayer or a protective layer may be provided.
  • the underlayer in the magnetic disk 10 is selected according to the magnetic film.
  • 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 is not limited to a single layer, and may have a multi-layer structure in which the same or different layers are stacked.
  • a multilayer underlayer such as Cr / Cr, Cr / CrMo, Cr / CrV, NiAl / Cr, NiAl / CrMo, or NiAl / CrV may be used.
  • Examples of the protective layer for preventing wear and corrosion of the magnetic thin film layer 2 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. In addition, these protective layers may be a single layer, or may have a multilayer structure including the same or different layers.
  • protective layers may be formed on the protective layer or instead of the protective layer.
  • colloidal silica fine particles are dispersed and coated on a Cr layer with tetraalkoxysilane diluted with an alcohol solvent, and then fired to form a silicon oxide (SiO2) layer. May be.
  • FIG. 3 is a flowchart showing a method for manufacturing the glass substrate 1 in the embodiment.
  • the glass substrate manufacturing method in the present embodiment includes a glass blank material preparation step (step S10), a glass substrate formation step (step S20), a grinding / polishing step (step S30), a chemical strengthening step (step S40), and a cleaning.
  • the process (step S50) is provided.
  • the magnetic thin film forming step (step S60) may be performed on the glass substrate (corresponding to the glass substrate 1 in FIG. 1) obtained through the chemical strengthening treatment step (step S40).
  • the magnetic disk 10 as an information recording medium is obtained by the magnetic thin film forming step (step S60).
  • the glass material constituting the glass substrate is melted (step S11).
  • general aluminosilicate glass is used as the glass material.
  • the aluminosilicate glass is composed of 58 mass% to 75 mass% SiO2, 5 mass% to 23 mass% Al2O3, 3 mass% to 10 mass% Li2O, and 4 mass% to 13 mass% Na2O. Contains as a main component.
  • the molten glass material is poured onto the lower mold and then press-molded with the upper mold and the lower mold (step S12).
  • a disk-shaped glass blank (glass base material) is formed by press molding.
  • the glass blank material may be formed by cutting out sheet glass (sheet glass) formed by a downdraw method or a float method with a grinding wheel. Further, the glass material is not limited to aluminosilicate glass, and may be any material.
  • the first lapping step is performed on both main surfaces of the press-molded glass blank material for the purpose of improving dimensional accuracy and shape accuracy (Ste S21).
  • Both main surfaces of a glass blank material are the main surfaces used as the front main surface 1A and the main surface used as the back main surface 1B in FIG. 1 through each process mentioned later (henceforth, both main surfaces) Also called).
  • alumina abrasive grains having a particle size of # 400 particles size of about 40 to 60 ⁇ m
  • the surface roughness Rmax is finished to about 6 ⁇ m.
  • a coring (inner peripheral cut) process is performed on the center portion of the glass blank using a cylindrical diamond drill or the like (step S22).
  • a coring process is performed on the center portion of the glass blank using a cylindrical diamond drill or the like.
  • a predetermined chamfering process may be performed on the hole in the center.
  • the outer peripheral end surface and the inner peripheral end surface of the glass substrate are polished into a mirror surface by a brush (step S22).
  • a slurry containing cerium oxide abrasive grains is used as the abrasive grains.
  • a second lapping process is performed on both main surfaces of the glass substrate (step S31).
  • the second lapping step is performed using a double-side polishing apparatus that uses a planetary gear mechanism. Specifically, press the surface plate from above and below both main surfaces of the glass blank material, supply water, grinding liquid or lubricating liquid onto both main surfaces, and move the glass blank material and the lapping surface plate relatively. Then, the second lapping step is performed.
  • the approximate parallelism, flatness, thickness, etc. of the glass substrate are preliminarily adjusted, and a glass base material having an approximately flat main surface is obtained.
  • fine abrasive grains are used as compared with the first lapping step in order to reduce the generated grinding marks. For example, by attaching fixed abrasive grains such as a diamond tile pad on a surface plate, both surfaces of the glass substrate are finished to a surface roughness Rmax of about 2 ⁇ m.
  • step S31 warping of the glass substrate is corrected while removing scratches remaining on both main surfaces of the glass substrate in the second lapping process (step S33).
  • a double-side polishing apparatus using a planetary gear mechanism is used.
  • polishing is performed using a polishing pad such as hard velor, urethane foam, or pitch-impregnated suede.
  • abrasive a slurry mainly composed of general cerium oxide abrasive grains is used.
  • the glass substrate is subjected to polishing again, and minute defects remaining on both main surfaces of the glass substrate are eliminated (step S34). Both main surfaces of the glass substrate are finished to have a mirror-like surface, thereby forming a desired flatness and eliminating the warpage of the glass substrate.
  • a double-side polishing apparatus using a planetary gear mechanism is used. For example, polishing is performed using a polishing pad which is a soft polisher made of suede or velor.
  • a slurry mainly composed of general colloidal silica that is finer than the cerium oxide used in the first polishing step is used.
  • FIG. 4 is a partial perspective view of a double-side polishing apparatus 2000 used in the polishing process.
  • the double-side polishing apparatus 2000 includes an upper surface plate (upper whetstone holding surface plate) 300, a lower surface plate (lower whetstone holding surface plate) 400, and a side (glass substrate side) facing the lower surface plate 400 of the upper surface plate 300.
  • the upper polishing pad 310 attached to the lower surface, and the lower polishing pad 410 attached to the upper surface on the side (glass substrate side) facing the upper surface plate 300 of the lower surface plate 400 are provided.
  • the upper polishing pad 310 and the lower polishing pad 410 are processing tools for polishing both main surfaces of the glass substrate 1.
  • the upper surface plate 300 and the lower surface plate 400 rotate in directions opposite to each other with respect to the revolution direction of the carrier 500.
  • Carrier 500 is arranged in a gap formed between upper surface plate 300 and lower surface plate 400. A plurality of disk-shaped glass substrates 1 are held by the carrier 500. The detailed structure of the carrier 500 will be described later.
  • the surfaces of the upper polishing pad 310 and the lower polishing pad 410 may be cleaned.
  • the cleaning of the surfaces of the upper polishing pad 310 and the lower polishing pad may be performed in any step in the polishing step (step S30), or may be performed in any step in the polishing step (step S30). Alternatively, it may be performed after the polishing process (step S30) ends.
  • the surfaces of the upper polishing pad 310 and the lower polishing pad 410 are cleaned in the double-side polishing apparatus 2000.
  • the surfaces of the upper polishing pad 310 and the lower polishing pad 410 may be periodically cleaned each time one or more polishings are performed, or may be cleaned irregularly.
  • the chemical strengthening layer is formed on both main surfaces of the glass substrate by immersing the glass substrate in the chemical strengthening treatment liquid (step S40).
  • the glass substrate 1 is immersed for about 30 minutes in a chemical strengthening treatment solution such as a mixture solution of potassium nitrate (70%) and sodium nitrate (30%) heated to 300 ° C. By doing so, chemical strengthening is performed.
  • alkali metal ions such as lithium ions and sodium ions contained in the glass substrate 1 are replaced by alkali metal ions such as potassium ions having a larger ion radius than these ions (ion exchange method).
  • Compressive stress is generated in the ion-exchanged region due to strain caused by the difference in ion radius, and both main surfaces of the glass substrate 1 are strengthened.
  • a chemical strengthening layer may be formed in a range from the surface of the glass substrate 1 to about 5 ⁇ m to improve the rigidity of the glass substrate 1. As described above, a glass substrate corresponding to the glass substrate 1 shown in FIG. 1 is obtained.
  • the glass substrate 1 may be further subjected to a polishing treatment with a machining allowance on both main surfaces of 0.1 ⁇ m to 0.5 ⁇ m.
  • a polishing treatment with a machining allowance on both main surfaces of 0.1 ⁇ m to 0.5 ⁇ m.
  • a chemical strengthening step may be performed between the first polishing step (rough polishing) and the second polishing step (precision polishing).
  • the glass substrate is cleaned (step S50).
  • the deposits attached to the two main surfaces of the glass substrate are removed.
  • the number of deposits on the surface of the glass substrate 1 is inspected using an optical defect inspection apparatus or the like.
  • the magnetic thin film layer 2 is formed by forming a magnetic film on both main surfaces (or one of the main surfaces) of the glass substrate (corresponding to the glass substrate 1 shown in FIG. 1) that has been subjected to the chemical strengthening treatment. Is done.
  • the magnetic thin film layer includes an adhesion layer made of a Cr alloy, a soft magnetic layer made of a CoFeZr alloy, an orientation control underlayer made of Ru, a perpendicular magnetic recording layer made of a CoCrPt alloy, a protective layer made of a C system, and a lubrication made of an F system. It is formed by sequentially depositing layers. By forming the magnetic thin film layer, a perpendicular magnetic recording disk corresponding to the magnetic disk 10 shown in FIG. 2 can be obtained.
  • the magnetic disk in the present embodiment is an example of a perpendicular magnetic disk composed of a magnetic thin film layer.
  • the magnetic disk may be composed of a magnetic layer or the like as a so-called in-plane magnetic disk.
  • FIG. 5 is a plan view showing a carrier 500 in the present embodiment
  • FIG. 6 is a plan view showing a dimensional relationship of the carrier in the present embodiment
  • FIG. 7 is a plan view of the glass substrate 1.
  • carrier 500 in the present embodiment has a disc-shaped main body 510, and the thickness is about 0.30 mm to 2.2 mm, which is thinner than the thickness of glass substrate 1 to be held. The thickness is selected. The diameter of the carrier 500 is about 430 mm.
  • aramid fiber, FRP (glass epoxy), PC (polycarbonate), or the like is used for the main body 510.
  • the carrier 500 is provided with 22 through-holding holes 520 for holding the glass substrate 1.
  • the through-holding holes 520 are arranged in a double ring shape, eight through-holding holes 520P are arranged at equal intervals on the inner annular line r1, and on the outer annular line r2. Fourteen through-holding holes 520P are arranged at equal intervals.
  • the diameter of the through-holding hole 520 is about 66.5 mm.
  • carrier 500 in the present embodiment has glass substrate non-holding region S that does not hold glass substrate 1.
  • the glass substrate non-holding region S is a region including a circular region surrounded by a radius Dmm from the center position C1 of the carrier 500 when the diameter of the glass substrate 1 is Dmm (see FIG. 7).
  • the center of the through-holding hole 520 is not provided in the circular region surrounded by the radius Dmm.
  • the thickness of the carrier 500 is thinner than other regions.
  • the area where the thickness is thin need not be circular.
  • the glass substrate non-holding region S includes a region surrounded by a circle having a radius of 65 mm.
  • five carriers 500 are annularly arranged between the upper surface plate 300 and the lower surface plate 400.
  • a gear is provided on the outer peripheral surface of the carrier 500, but the illustration of the gear is omitted. Further, the radius of the carrier 500 means a dimension when measured with a gear tip circle.
  • FIG. 8 shows the carrier 500 when the first through-holding hole 520 ⁇ / b> C is provided at the center of the carrier 500.
  • the lower polishing pad 410 is driven as shown in FIG. In the vicinity of the middle belt region B1, the substantial transit time of the carrier 500 and the glass substrate 1 is longer than that of the outer peripheral region B2 and the inner peripheral region B3. As a result, a difference in wear state of the lower polishing pad 410 (partial wear) occurs between the outer peripheral region B2, the inner peripheral region B3, and the middle belt region B1. Due to this uneven wear, the flatness of the glass substrate 1 varies. This occurs not only in the lower polishing pad 410 but also in the upper polishing pad 310.
  • the carrier 500 in the present embodiment shown in FIG. 5 is provided with a non-through holding hole forming region S at the center position C1 of the carrier 500.
  • the frequency with which the glass substrate 1 passes through the middle band region B1 can be reduced.
  • the wear state of the upper polishing pad 310 and the lower polishing pad 410 differs between the outer peripheral region B2 and inner peripheral region B3 of the upper polishing pad 310 and the lower polishing pad 410 and the middle belt region B1 (partial wear). ) Can be suppressed.
  • Example 2 Examples and comparative examples of the method for producing the glass substrate for information recording medium will be described below.
  • the processes up to the “first polishing step (rough polishing)” of S33 shown in FIG. 3 were performed as described above.
  • the total number of glass substrates is 110 in each example and 115 in the comparative example.
  • Example 1 the carrier 500 shown in FIG. 5 was used.
  • Example 2 as shown in FIG. 9, a carrier 500 having one auxiliary through hole 520M having a diameter of 80 mm, which is larger than the through holding hole 520, at the center position C1 of the carrier was used. Since the auxiliary through hole 520M has a diameter that is too large compared to the diameter of the glass substrate 1, the auxiliary through hole 520M cannot be used as the through holding hole 520 for holding the glass substrate 1. Arbitrary chamfering treatment may be performed on the outer periphery of the auxiliary through hole so that the polishing pad is not damaged during processing.
  • a configuration is provided in which a plurality (three in FIG. 10) of auxiliary through holes 520M having a diameter smaller than the diameter of the through holding hole 520 are provided so as to have an opening area equivalent to that of the auxiliary through hole 520M. It may be adopted. Since the diameter of the auxiliary through hole 520M is smaller than the diameter of the through holding hole 520, it cannot be used as the through holding hole 520 for holding the glass substrate 1. Arbitrary chamfering treatment may be performed on the outer periphery of the auxiliary through hole so that the polishing pad is not damaged during processing.
  • the double-side polishing apparatus used in the second polishing step is preliminarily processed using a glass substrate different from the glass substrate used in this test, and the upper and lower polishing pads are used.
  • the second polishing step was carried out after adjusting the conditions showing the inherent tendency. Specifically, before carrying out this test, the double-side polishing apparatus used in this test is used so that the carrier used in each example and each comparative example is used and the total machining time is approximately 40 hours in total.
  • the glass substrate was processed in advance using The glass substrate similar to the glass substrate created in the procedure up to the above-mentioned step S33 was used for the pre-processing. By the pre-processing, the wear on the polishing pad, which is specific to the carrier of the example and the comparative example, can be seen.
  • Example 1 End measurement of glass substrate
  • Example 2 the evaluation result in Example 1, Example 2, and the comparative example 1 is shown.
  • the surface shape of the glass substrate was measured using Optiflat II manufactured by Phase Shift Technology.
  • the difference between the height of the lowest point and the height of the highest point in the glass substrate surface was analyzed.
  • a value of the analysis result of 0.6 ⁇ m or less was determined as a non-defective product.
  • 50 glass substrates were measured, respectively, and the ratio of non-defective products was investigated.
  • An analysis result of less than 90% was evaluated as “C” and rejected, and 90% or more was evaluated as “A” and passed.
  • an analysis result of 94% or more was evaluated as “AA” and passed.
  • Comparative Example 1 As a result of analysis, the flatness was poor in Comparative Example 1, and the flatness was good in Examples 1 and 2.
  • Comparative Example 1 With the passage of the glass substrate, the pad surface is worn in a slightly wide range of the middle band region of the surface plate, and the glass substrate being polished cannot keep parallel to the surface plate, and the flatness deteriorates. It is thought that led to.
  • Example 1 and Example 2 uneven wear in the middle band region of the surface plate was suppressed, and deterioration of the flatness of the glass substrate due to the “second polishing step (precision polishing) (S34)” was suppressed. It is considered a thing.
  • the frequency with which the carrier 500 passes through the middle band region is also reduced, it is considered that uneven wear due to this is suppressed, and improvement in flatness deterioration is suppressed.
  • This information recording medium was incorporated into a hard drive and a read / write test was conducted. Compared to Comparative Example 1, in Examples 1 and 2, the percentage of hard drives that cleared the reference value was high. In particular, in Example 2, the ratio of hard drives that cleared the reference value was high.
  • the above embodiment describes the case where the present invention is applied to the second polishing step (precise polishing) S34.
  • the present invention is applied to the first polishing step (rough polishing) S33.
  • the present invention is applied to both the first polishing step (rough polishing) S33 and the second polishing step (precision polishing) S34, the same effects can be obtained.

Abstract

　A carrier (500) has a glass-substrate non-holding region (S) that does not hold a glass substrate (1). If the diameter of the glass substrate (1) is Dmm, the glass-substrate non-holding region (S) includes a circular region encompassing a radius of Dmm from the center position (C1) of the carrier (500). Thus provided are a manufacturing method for a glass substrate for an information recording medium, and an information recording medium, said manufacturing method enabling the suppression of the occurrence of differences in the state of wear of polishing pads in the interval between the outer peripheral region and the inner peripheral region of the polishing pad, and the intermediate region that is present therebetween, when polishing using a double disc polishing device.

Description

情報記録媒体用ガラス基板の製造方法および情報記録媒体Method for manufacturing glass substrate for information recording medium and information recording medium
　本発明は、情報記録媒体用ガラス基板の製造方法および情報記録媒体に関し、特に、情報記録媒体の製造に用いられる情報記録媒体用ガラス基板の製造方法、およびその情報記録媒体用ガラス基板を備えた情報記録媒体に関する。 The present invention relates to a method for manufacturing a glass substrate for information recording medium and an information recording medium, and in particular, includes a method for manufacturing a glass substrate for information recording medium used for manufacturing an information recording medium, and the glass substrate for information recording medium. The present invention relates to an information recording medium.
　磁気ディスクなどの情報記録媒体は、コンピュータなどにハードディスクとして搭載される。情報記録媒体は、基板の表面上に、磁気、光、または光磁気などの性質を利用した記録層を含む磁気薄膜層が形成されて製造される。記録層が磁気ヘッドによって磁化されることによって、所定の情報が情報記録媒体に記録される。 An information recording medium such as a magnetic disk is mounted as a hard disk on a computer or the like. An information recording medium is manufactured by forming a magnetic thin film layer including a recording layer using properties such as magnetism, light, or magnetomagnetism on the surface of a substrate. As the recording layer is magnetized by the magnetic head, predetermined information is recorded on the information recording medium.
　情報記録媒体は年々記録密度が向上している。それに伴い情報記録媒体に使用される基板の品質にも高い品質が要求されている。情報記録媒体用の基板としては、従来アルミニウム基板が用いられてきたが、記録密度の向上に伴い、アルミニウム基板に比較して基板表面の平滑性および強度に優れるガラス基板に徐々に置き換わりつつある。 The recording density of information recording media is improving year by year. Accordingly, high quality is required for the quality of substrates used for information recording media. Conventionally, an aluminum substrate has been used as a substrate for an information recording medium. However, as the recording density is improved, it is gradually being replaced by a glass substrate that is superior in smoothness and strength of the substrate surface as compared with an aluminum substrate.
　情報記録媒体用のガラス基板の製造方法では、高い表面形状精度を確保するための研削工程／研磨工程を有している。ガラス基板の高精度な形状品質を達成するために、加工処理能力の異なるスラリーや研削／研磨パッドを効果的に組み合わせた２段階以上の研削／研磨工程が適用されている。従来のガラス基板の製造に関する技術は、たとえば特開２００７－０１５１０５号公報（特許文献１）に開示されている。 The method for producing a glass substrate for an information recording medium has a grinding process / polishing process for ensuring high surface shape accuracy. In order to achieve high-precision shape quality of the glass substrate, two or more stages of grinding / polishing processes in which slurry and grinding / polishing pads having different processing capabilities are effectively combined are applied. For example, Japanese Unexamined Patent Application Publication No. 2007-015105 (Patent Document 1) discloses a conventional technology relating to glass substrate manufacturing.
特開２００７－０１５１０５号公報Japanese Patent Laid-Open No. 2007-015105
　近年、ハードディスクドライブにおけるヘッドの浮上特性等の理由から、ガラス基板の平坦度に対して要求水準が高まっており、ガラス基板の平坦度のバラツキの大きさが課題となっている。ガラス基板に生じる平坦度のバラツキの原因を調査したところ、ガラス基板の加工中に、ガラス基板を保持するキャリアが定盤上を通過する時間の、定盤面内での分布が影響している事が分かった。 In recent years, the requirement level for the flatness of the glass substrate has been increasing due to the flying characteristics of the head in the hard disk drive, and the variation in the flatness of the glass substrate has become a problem. When the cause of the flatness variation generated on the glass substrate was investigated, the distribution of the time required for the carrier holding the glass substrate to pass on the surface plate during the processing of the glass substrate was affected. I understood.
　すなわち、両面研磨装置とキャリアとを使用した研磨では、定盤の内周領域と外周領域の中間にある領域（以下、中帯領域と称する。）付近は、キャリアおよびガラス基板（ワーク）の実質的な通過時間が、外周領域および内周領域に比較して長い。その結果、外周領域および内周領域と中帯領域との間において、研磨パッドの摩耗状態に違い（偏摩耗）が生じることとなる。この偏摩耗が原因となり、ガラス基板の平坦度にバラツキが発生していた。 That is, in the polishing using the double-side polishing apparatus and the carrier, the area around the inner peripheral area and the outer peripheral area of the surface plate (hereinafter referred to as the middle band area) is substantially the carrier and the glass substrate (workpiece). The typical transit time is longer than that of the outer peripheral region and the inner peripheral region. As a result, a difference in wear state of the polishing pad (uneven wear) occurs between the outer peripheral region and the inner peripheral region and the middle belt region. Due to this uneven wear, there was variation in the flatness of the glass substrate.
　本発明は上記課題に鑑みてなされたものであり、両面研磨装置を用いた研磨工程において、研磨パッドの外周領域および内周領域と、これらの中間に存在する中帯領域との間において、研磨パッドの摩耗状態に差（偏摩耗）が生じることを抑制することが可能な、情報記録媒体用ガラス基板の製造方法および情報記録媒体を提供することにある。 The present invention has been made in view of the above problems, and in a polishing process using a double-side polishing apparatus, polishing is performed between an outer peripheral region and an inner peripheral region of a polishing pad, and a middle belt region existing between them. An object of the present invention is to provide a method for manufacturing a glass substrate for an information recording medium and an information recording medium that can suppress the occurrence of a difference (partial wear) in the wear state of the pad.
　この発明に基づいた情報記録媒体用ガラス基板の製造方法においては、円形ディスク形状のガラス基板の主表面に磁気薄膜層が形成される情報記録媒体用ガラス基板の製造方法であって、遊星歯車機構を備えた両面研磨装置を用いて上記ガラス基板の主表面を、研磨剤を供給しながら研磨する表面研磨工程を有する。 The method for manufacturing a glass substrate for information recording medium according to the present invention is a method for manufacturing a glass substrate for information recording medium in which a magnetic thin film layer is formed on the main surface of a circular disk-shaped glass substrate, comprising a planetary gear mechanism. And a surface polishing step of polishing the main surface of the glass substrate while supplying an abrasive.
　上記両面研磨装置は、上記ガラス基板の上側に位置し、上記ガラス基板側に上側研磨パッドを有する上定盤と、上記ガラス基板の下側に位置し、上記ガラス基板側に下側研磨パッドを有する下定盤と、上記ガラス基板を保持する貫通保持孔が複数設けられ、上記上側研磨パッドと上記下側研磨パッドとにより挟み込まれるとともに、上記遊星歯車機構により所定の回転運動を行なう円盤状のキャリアとを備える。 The double-side polishing apparatus is located on the upper side of the glass substrate, has an upper surface plate having an upper polishing pad on the glass substrate side, and is located on the lower side of the glass substrate, and has a lower polishing pad on the glass substrate side. A disk-shaped carrier that is provided with a plurality of through-holding holes for holding the glass substrate and is sandwiched between the upper polishing pad and the lower polishing pad and that performs a predetermined rotational movement by the planetary gear mechanism. With.
　上記キャリアは、上記ガラス基板を保持しないガラス基板非保持領域を有し、上記ガラス基板非保持領域は、上記ガラス基板の直径をＤｍｍとした場合に、上記キャリアの中心位置から半径Ｄｍｍで囲まれた円領域を含む。 The carrier has a glass substrate non-holding region that does not hold the glass substrate, and the glass substrate non-holding region is surrounded by a radius Dmm from the center position of the carrier when the diameter of the glass substrate is Dmm. Includes a circular area.
　他の形態においては、上記ガラス基板非保持領域において、上記キャリアの中心位置から半径Ｄｍｍで囲まれた円領域には、上記貫通保持孔の中心は設けられていない。 In another embodiment, in the glass substrate non-holding region, the center of the through-holding hole is not provided in a circular region surrounded by a radius Dmm from the center position of the carrier.
　他の形態においては、上記ガラス基板非保持領域は、上記ガラス基板を保持することができない補助貫通孔を有する。 In another embodiment, the glass substrate non-holding region has an auxiliary through hole that cannot hold the glass substrate.
　この発明に基づいた情報記録媒体においては、上記のいずれかに記載の情報記録媒体用ガラス基板の製造方法によって得られたガラス基板と、上記ガラス基板の主表面に形成された磁気薄膜層とを備える。 In the information recording medium based on this invention, the glass substrate obtained by the manufacturing method of the glass substrate for information recording media described in any of the above, and the magnetic thin film layer formed on the main surface of the glass substrate Prepare.
　本発明によれば、両面研磨装置を用いた研磨工程において、研磨パッドの外周領域および内周領域と中帯領域との間において、研磨パッドの摩耗状態に差が生じることを抑制することが可能な、情報記録媒体用ガラス基板の製造方法および情報記録媒体を提供することを可能する。 According to the present invention, in the polishing process using the double-side polishing apparatus, it is possible to suppress the occurrence of a difference in the wear state of the polishing pad between the outer peripheral region and the inner peripheral region and the middle belt region of the polishing pad. Further, it is possible to provide a method for manufacturing a glass substrate for an information recording medium and an information recording medium.
実施の形態におけるガラス基板の製造方法によって得られるガラス基板を示す斜視図である。It is a perspective view which shows the glass substrate obtained by the manufacturing method of the glass substrate in embodiment. 実施の形態におけるガラス基板の製造方法によって得られるガラス基板を備えた磁気ディスクを示す斜視図である。It is a perspective view which shows the magnetic disc provided with the glass substrate obtained by the manufacturing method of the glass substrate in embodiment. 実施の形態におけるガラス基板の製造方法を示すフローチャート図である。It is a flowchart figure which shows the manufacturing method of the glass substrate in embodiment. 研磨工程に用いられる両面研磨装置の部分斜視図である。It is a fragmentary perspective view of the double-side polish apparatus used for a grinding | polishing process. 実施の形態におけるキャリアを示す平面図である。It is a top view which shows the carrier in embodiment. 実施の形態におけるキャリアの寸法関係を示す平面図である。It is a top view which shows the dimensional relationship of the carrier in embodiment. ガラス基板の平面図である。It is a top view of a glass substrate. 参考技術におけるキャリアを示す平面図である。It is a top view which shows the carrier in a reference technique. 他の実施の形態におけるキャリアを示す平面図である。It is a top view which shows the carrier in other embodiment. さらに他の実施の形態におけるキャリアを示す平面図である。It is a top view which shows the carrier in other embodiment. 実施例１－２、比較例１における端面形状の評価結果を示す図である。It is a figure which shows the evaluation result of the end surface shape in Example 1-2 and Comparative Example 1.
　本発明に基づいた実施の形態および実施例について、以下、図面を参照しながら説明する。実施の形態および実施例の説明において、個数、量などに言及する場合、特に記載がある場合を除き、本発明の範囲は必ずしもその個数、量などに限定されない。実施の形態および実施例の説明において、同一の部品、相当部品に対しては、同一の参照番号を付し、重複する説明は繰り返さない場合がある。 Embodiments and examples based on the present invention will be described below with reference to the drawings. In the description of the embodiments and examples, when referring to the number, amount, and the like, the scope of the present invention is not necessarily limited to the number, amount, and the like, unless otherwise specified. In the description of the embodiments and examples, the same parts and corresponding parts are denoted by the same reference numerals, and redundant description may not be repeated.
　［ガラス基板１・磁気ディスク１０］
　図１および図２を参照して、まず、本実施の形態に基づく情報記録媒体用ガラス基板の製造方法によって得られるガラス基板１、およびガラス基板１を備えた磁気ディスク１０について説明する。図１は、磁気ディスク１０（図２参照）に用いられるガラス基板１を示す斜視図である。図２は、情報記録媒体として、ガラス基板１を備えた磁気ディスク１０を示す斜視図である。 [Glass substrate 1 and magnetic disk 10]
With reference to FIG. 1 and FIG. 2, the glass substrate 1 obtained by the manufacturing method of the glass substrate for information recording media based on this Embodiment and the magnetic disc 10 provided with the glass substrate 1 are demonstrated first. FIG. 1 is a perspective view showing a glass substrate 1 used for a magnetic disk 10 (see FIG. 2). FIG. 2 is a perspective view showing a magnetic disk 10 provided with a glass substrate 1 as an information recording medium.
　図１に示すように、磁気ディスク１０に用いられるガラス基板１（情報記録媒体用ガラス基板）は、中心に孔１Ｈが形成された環状の円板形状を呈している。円形ディスク形状のガラス基板１は、表主表面１Ａ、裏主表面１Ｂ、内周端面１Ｃ、および外周端面１Ｄを有している。 As shown in FIG. 1, a glass substrate 1 (glass substrate for information recording medium) used for a magnetic disk 10 has an annular disk shape with a hole 1H formed in the center. The circular disk-shaped glass substrate 1 has a front main surface 1A, a back main surface 1B, an inner peripheral end surface 1C, and an outer peripheral end surface 1D.
　ガラス基板１の大きさは、特に制限はなく、たとえば外径０．８インチ、１．０インチ、１．８インチ、２．５インチ、または３．５インチなどである。ガラス基板１の厚さは、破損防止の観点から、たとえば０．３０ｍｍ～２．２ｍｍである。本実施の形態におけるガラス基板１の大きさは、外径が約６５ｍｍ、内径が約２０ｍｍ、厚さが約０．８ｍｍである。ガラス基板１の厚さとは、ガラス基板１上の点対称となる任意の複数の点で測定した値の平均によって算出される値である。 The size of the glass substrate 1 is not particularly limited, and is, for example, 0.8 inch, 1.0 inch, 1.8 inch, 2.5 inch, or 3.5 inch outer diameter. The thickness of the glass substrate 1 is, for example, 0.30 mm to 2.2 mm from the viewpoint of preventing breakage. As for the size of the glass substrate 1 in the present embodiment, the outer diameter is about 65 mm, the inner diameter is about 20 mm, and the thickness is about 0.8 mm. The thickness of the glass substrate 1 is a value calculated by averaging the values measured at a plurality of arbitrary points that are point-symmetric on the glass substrate 1.
　図２に示すように、磁気ディスク１０は、上記したガラス基板１の表主表面１Ａ上に磁性膜が成膜されて、磁気記録層を含む磁気薄膜層２が形成される。図２中では、表主表面１Ａ上にのみ磁気薄膜層２が形成されているが、裏主表面１Ｂ上にも磁気薄膜層２が形成されていてもよい。 As shown in FIG. 2, in the magnetic disk 10, a magnetic film is formed on the front main surface 1A of the glass substrate 1 to form a magnetic thin film layer 2 including a magnetic recording layer. In FIG. 2, the magnetic thin film layer 2 is formed only on the front main surface 1A, but the magnetic thin film layer 2 may also be formed on the back main surface 1B.
　磁気薄膜層２は、磁性粒子を分散させた熱硬化性樹脂をガラス基板１の表主表面１Ａ上にスピンコートすることによって形成される（スピンコート法）。磁気薄膜層２は、ガラス基板１の表主表面１Ａに対してスパッタリング法、または無電解めっき法等により形成されてもよい。 The magnetic thin film layer 2 is formed by spin-coating a thermosetting resin in which magnetic particles are dispersed on the front main surface 1A of the glass substrate 1 (spin coating method). The magnetic thin film layer 2 may be formed on the front main surface 1A of the glass substrate 1 by a sputtering method, an electroless plating method, or the like.
　ガラス基板１の表主表面１Ａに形成される磁気薄膜層２の膜厚は、スピンコート法の場合は約０．３μｍ～約１．２μｍ、スパッタリング法の場合は約０．０４μｍ～約０．０８μｍ、無電解めっき法の場合は約０．０５μｍ～約０．１μｍである。薄膜化および高密度化の観点からは、磁気薄膜層２はスパッタリング法または無電解めっき法によって形成されるとよい。 The film thickness of the magnetic thin film layer 2 formed on the front main surface 1A of the glass substrate 1 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 electroless plating, the thickness is about 0.05 μm to about 0.1 μm. From the viewpoint of thinning and high density, the magnetic thin film layer 2 is preferably formed by sputtering or electroless plating.
　磁気薄膜層２に用いる磁性材料としては、特に限定はなく従来公知のものが使用できるが、高い保持力を得るために結晶異方性の高いＣｏを基本とし、残留磁束密度を調整する目的でＮｉやＣｒを加えたＣｏ系合金などが好適である。また、熱アシスト記録用に好適な磁性層材料として、ＦｅＰｔ系の材料が用いられてもよい。 The magnetic material used for the magnetic thin film layer 2 is not particularly limited, and a conventionally known material can be used. However, in order to obtain a high coercive force, Co having high crystal anisotropy is basically used for the purpose of adjusting the residual magnetic flux density. A Co-based alloy to which Ni or Cr is added is suitable. Further, as a magnetic layer material suitable for heat-assisted recording, an FePt-based material may be used.
　また、磁気記録ヘッドの滑りをよくするために磁気薄膜層２の表面に潤滑剤を薄くコーティングしてもよい。潤滑剤としては、たとえば液体潤滑剤であるパーフロロポリエーテル（ＰＦＰＥ）をフレオン系などの溶媒で希釈したものが挙げられる。 Further, a lubricant may be thinly coated on the surface of the magnetic thin film layer 2 in order to improve the sliding of the magnetic recording head. Examples of the lubricant include those obtained by diluting perfluoropolyether (PFPE), which is a liquid lubricant, with a solvent such as Freon.
　さらに、必要により下地層や保護層を設けてもよい。磁気ディスク１０における下地層は磁性膜に応じて選択される。下地層の材料としては、たとえば、Ｃｒ、Ｍｏ、Ｔａ、Ｔｉ、Ｗ、Ｖ、Ｂ、Ａｌ、またはＮｉなどの非磁性金属から選ばれる少なくとも一種以上の材料が挙げられる。 Furthermore, if necessary, an underlayer or a protective layer may be provided. The underlayer in the magnetic disk 10 is selected according to the 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.
　また、下地層は単層とは限らず、同一または異種の層を積層した複数層構造としても構わない。たとえば、Ｃｒ／Ｃｒ、Ｃｒ／ＣｒＭｏ、Ｃｒ／ＣｒＶ、ＮｉＡｌ／Ｃｒ、ＮｉＡｌ／ＣｒＭｏ、ＮｉＡｌ／ＣｒＶ等の多層下地層としてもよい。 Also, the underlayer is not limited to a single layer, and may have a multi-layer structure in which the same or different layers are stacked. For example, a multilayer underlayer such as Cr / Cr, Cr / CrMo, Cr / CrV, NiAl / Cr, NiAl / CrMo, or NiAl / CrV may be used.
　磁気薄膜層２の摩耗や腐食を防止する保護層としては、たとえば、Ｃｒ層、Ｃｒ合金層、カーボン層、水素化カーボン層、ジルコニア層、シリカ層などが挙げられる。これらの保護層は、下地層、磁性膜など共にインライン型スパッタ装置で連続して形成できる。また、これらの保護層は、単層としてもよく、あるいは、同一または異種の層からなる多層構成としてもよい。 Examples of the protective layer for preventing wear and corrosion of the magnetic thin film layer 2 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. In addition, these protective layers may be a single layer, or may have a multilayer structure including the same or different layers.
　上記保護層上に、あるいは上記保護層に替えて、他の保護層を形成してもよい。たとえば、上記保護層に替えて、Ｃｒ層の上にテトラアルコキシシランをアルコール系の溶媒で希釈した中に、コロイダルシリカ微粒子を分散して塗布し、さらに焼成して酸化ケイ素（ＳｉＯ２）層を形成してもよい。 Other protective layers may be formed on the protective layer or instead of the protective layer. For example, instead of the protective layer, colloidal silica fine particles are dispersed and coated on a Cr layer with tetraalkoxysilane diluted with an alcohol solvent, and then fired to form a silicon oxide (SiO2) layer. May be.
　［ガラス基板の製造方法］
　次に、図３に示すフローチャート図を用いて、本実施の形態における情報記録媒体用ガラス基板（以下、単にガラス基板と称する。）の製造方法について説明する。図３は、実施の形態におけるガラス基板１の製造方法を示すフローチャート図である。 [Glass substrate manufacturing method]
Next, a method for manufacturing a glass substrate for information recording medium (hereinafter simply referred to as a glass substrate) in the present embodiment will be described with reference to the flowchart shown in FIG. FIG. 3 is a flowchart showing a method for manufacturing the glass substrate 1 in the embodiment.
　本実施の形態におけるガラス基板の製造方法は、ガラスブランク材準備工程（ステップＳ１０）、ガラス基板形成工程（ステップＳ２０）、研削／研磨工程（ステップＳ３０）、化学強化工程（ステップＳ４０）、および洗浄工程（ステップＳ５０）を備えている。化学強化処理工程（ステップＳ４０）を経ることによって得られたガラス基板（図１におけるガラス基板１に相当）に対して、磁気薄膜形成工程（ステップＳ６０）が実施されてもよい。磁気薄膜形成工程（ステップＳ６０）によって、情報記録媒体としての磁気ディスク１０が得られる。 The glass substrate manufacturing method in the present embodiment includes a glass blank material preparation step (step S10), a glass substrate formation step (step S20), a grinding / polishing step (step S30), a chemical strengthening step (step S40), and a cleaning. The process (step S50) is provided. The magnetic thin film forming step (step S60) may be performed on the glass substrate (corresponding to the glass substrate 1 in FIG. 1) obtained through the chemical strengthening treatment step (step S40). The magnetic disk 10 as an information recording medium is obtained by the magnetic thin film forming step (step S60).
　以下、これらの各ステップＳ１０～Ｓ６０の詳細について順に説明する、以下には、各ステップＳ１０～Ｓ６０間に適宜行なわれる簡易的な洗浄については記載していない。 Hereinafter, details of each of these steps S10 to S60 will be described in order. In the following, simple cleaning appropriately performed between each of steps S10 to S60 is not described.
　（ガラスブランク材準備工程）
　ガラスブランク材準備工程（ステップＳ１０）においては、ガラス基板を構成するガラス素材が溶融される（ステップＳ１１）。ガラス素材は、たとえば一般的なアルミノシリケートガラスが用いられる。アルミノシリケートガラスは、５８質量％～７５質量％のＳｉＯ２と、５質量％～２３質量％のＡｌ２Ｏ３と、３質量％～１０質量％のＬｉ２Ｏと、４質量％～１３質量％のＮａ２Ｏと、を主成分として含有する。溶融したガラス素材は、下型上に流し込まれた後、上型および下型によってプレス成形される（ステップＳ１２）。プレス成形によって、円盤状のガラスブランク材（ガラス母材）が形成される。 (Glass blank material preparation process)
In the glass blank material preparation step (step S10), the glass material constituting the glass substrate is melted (step S11). For example, general aluminosilicate glass is used as the glass material. The aluminosilicate glass is composed of 58 mass% to 75 mass% SiO2, 5 mass% to 23 mass% Al2O3, 3 mass% to 10 mass% Li2O, and 4 mass% to 13 mass% Na2O. Contains as a main component. The molten glass material is poured onto the lower mold and then press-molded with the upper mold and the lower mold (step S12). A disk-shaped glass blank (glass base material) is formed by press molding.
　ガラスブランク材は、ダウンドロー法またはフロート法によって形成されたシートガラス（板ガラス）を、研削砥石で切り出すことによって形成されてもよい。またガラス素材も、アルミノシリケートガラスに限られるものではなく、任意の素材であってもよい。 The glass blank material may be formed by cutting out sheet glass (sheet glass) formed by a downdraw method or a float method with a grinding wheel. Further, the glass material is not limited to aluminosilicate glass, and may be any material.
　（ガラス基板形成工程）
　次に、ガラス基板形成工程（ステップＳ２０）においては、プレス成形されたガラスブランク材の両方の主表面に対して、寸法精度および形状精度の向上を目的として、第１ラップ工程が施される（ステップＳ２１）。ガラスブランク材の両方の主表面とは、後述する各処理を経ることによって、図１における表主表面１Ａとなる主表面および裏主表面１Ｂとなる主表面のことである（以下、両主表面ともいう）。たとえば、粒度＃４００のアルミナ砥粒（粒径約４０～６０μｍ）を用い、表面粗さＲｍａｘで６μｍ程度に仕上げる。 (Glass substrate forming process)
Next, in the glass substrate forming step (step S20), the first lapping step is performed on both main surfaces of the press-molded glass blank material for the purpose of improving dimensional accuracy and shape accuracy ( Step S21). Both main surfaces of a glass blank material are the main surfaces used as the front main surface 1A and the main surface used as the back main surface 1B in FIG. 1 through each process mentioned later (henceforth, both main surfaces) Also called). For example, alumina abrasive grains having a particle size of # 400 (particle size of about 40 to 60 μm) are used, and the surface roughness Rmax is finished to about 6 μm.
　第１ラップ工程の後、円筒状のダイヤモンドドリルなどを用いて、ガラスブランク材の中心部に対してコアリング（内周カット）処理が施される（ステップＳ２２）。コアリング処理によって、中心部に孔の開いた円環状のガラス基板が得られる。中心部の孔に対しては、所定の面取り加工が施されてもよい。 After the first lapping step, a coring (inner peripheral cut) process is performed on the center portion of the glass blank using a cylindrical diamond drill or the like (step S22). By the coring process, an annular glass substrate having a hole in the center is obtained. A predetermined chamfering process may be performed on the hole in the center.
　また、ガラス基板の外周端面および内周端面がブラシによって鏡面状に研磨される（ステップＳ２２）。研磨砥粒としては、酸化セリウム砥粒を含むスラリーが用いられる。 Further, the outer peripheral end surface and the inner peripheral end surface of the glass substrate are polished into a mirror surface by a brush (step S22). As the abrasive grains, a slurry containing cerium oxide abrasive grains is used.
　（研削／研磨工程）
　次に、研削／研磨工程（ステップＳ３０）においては、ガラス基板の両主表面に対して第２ラップ工程が施される（ステップＳ３１）。第２ラップ工程は、遊星歯車機構を利用した両面研磨装置を用いて行なわれる。具体的には、ガラスブランク材の両主表面に上下から定盤を押圧させ、水、研削液または潤滑液を両主表面上に供給し、ガラスブランク材とラップ定盤とを相対的に移動させて、第２ラップ工程が行なわれる。 (Grinding / polishing process)
Next, in the grinding / polishing process (step S30), a second lapping process is performed on both main surfaces of the glass substrate (step S31). The second lapping step is performed using a double-side polishing apparatus that uses a planetary gear mechanism. Specifically, press the surface plate from above and below both main surfaces of the glass blank material, supply water, grinding liquid or lubricating liquid onto both main surfaces, and move the glass blank material and the lapping surface plate relatively. Then, the second lapping step is performed.
　第２ラップ工程（ステップＳ３１）によって、ガラス基板としてのおおよその平行度、平坦度、および厚みなどが予備調整され、おおよそ平坦な主表面を有するガラス母材が得られる。第２ラップ工程では、発生する研削痕を小さくするため、前記第１ラップ工程と比較して微細な砥粒を用いる。たとえば、定盤上にダイヤモンドタイルパッド等の固定砥粒を取りつける事により、ガラス基板両面上を表面粗さＲｍａｘで２μｍ程度に仕上げる。 In the second lapping step (step S31), the approximate parallelism, flatness, thickness, etc. of the glass substrate are preliminarily adjusted, and a glass base material having an approximately flat main surface is obtained. In the second lapping step, fine abrasive grains are used as compared with the first lapping step in order to reduce the generated grinding marks. For example, by attaching fixed abrasive grains such as a diamond tile pad on a surface plate, both surfaces of the glass substrate are finished to a surface roughness Rmax of about 2 μm.
　次に、第１ポリッシュ工程（粗研磨）として、第２ラップ工程（ステップＳ３１）においてガラス基板の両主表面に残留したキズを除去しつつ、ガラス基板の反りを矯正する（ステップＳ３３）。第１ポリッシュ工程においては、遊星歯車機構を利用した両面研磨装置が使用される。たとえば、硬質ベロア、ウレタン発泡、またはピッチ含浸スウェードなどの研磨パッドを用いて研磨が行なわれる。研磨剤としては、一般的な酸化セリウム砥粒を主成分とするスラリーが用いられる。 Next, as a first polishing process (rough polishing), warping of the glass substrate is corrected while removing scratches remaining on both main surfaces of the glass substrate in the second lapping process (step S31) (step S33). In the first polishing process, a double-side polishing apparatus using a planetary gear mechanism is used. For example, polishing is performed using a polishing pad such as hard velor, urethane foam, or pitch-impregnated suede. As the abrasive, a slurry mainly composed of general cerium oxide abrasive grains is used.
　第２ポリッシュ工程（精密研磨）においては、ガラス基板に研磨加工が再度実施され、ガラス基板の両主表面上に残留した微小欠陥等が解消される（ステップＳ３４）。ガラス基板の両主表面は鏡面状に仕上げられることによって所望の平坦度に形成され、ガラス基板の反りも解消される。第２ポリッシュ工程においては、遊星歯車機構を利用した両面研磨装置が使用される。たとえば、スウェードまたはベロアを素材とする軟質ポリッシャである研磨パッドを用いて研磨が行なわれる。研磨剤としては、第１ポリッシュ工程で用いた酸化セリウムよりも微細な、一般的なコロイダルシリカを主成分とするスラリーが用いられる。 In the second polishing step (precise polishing), the glass substrate is subjected to polishing again, and minute defects remaining on both main surfaces of the glass substrate are eliminated (step S34). Both main surfaces of the glass substrate are finished to have a mirror-like surface, thereby forming a desired flatness and eliminating the warpage of the glass substrate. In the second polishing step, a double-side polishing apparatus using a planetary gear mechanism is used. For example, polishing is performed using a polishing pad which is a soft polisher made of suede or velor. As the abrasive, a slurry mainly composed of general colloidal silica that is finer than the cerium oxide used in the first polishing step is used.
　ここで、図４を参照して、両面研磨装置２０００の概略構成について説明する。図４は、研磨工程に用いられる両面研磨装置２０００の部分斜視図である。 Here, a schematic configuration of the double-side polishing apparatus 2000 will be described with reference to FIG. FIG. 4 is a partial perspective view of a double-side polishing apparatus 2000 used in the polishing process.
　両面研磨装置２０００は、上定盤（上側砥石保持定盤）３００と、下定盤（下側砥石保持定盤）４００と、上定盤３００の下定盤４００に対向する側（ガラス基板側）の下面に取り付けられた上側研磨パッド３１０と、下定盤４００の上定盤３００に対向する側（ガラス基板側）の上面に取り付けられた下側研磨パッド４１０と、を備える。 The double-side polishing apparatus 2000 includes an upper surface plate (upper whetstone holding surface plate) 300, a lower surface plate (lower whetstone holding surface plate) 400, and a side (glass substrate side) facing the lower surface plate 400 of the upper surface plate 300. The upper polishing pad 310 attached to the lower surface, and the lower polishing pad 410 attached to the upper surface on the side (glass substrate side) facing the upper surface plate 300 of the lower surface plate 400 are provided.
　上側研磨パッド３１０および下側研磨パッド４１０は、ガラス基板１の両主表面を研磨加工するための加工工具である。上定盤３００と下定盤４００とは、キャリア５００の公転方向に対して互いに反対方向に回転するようになっている。上定盤３００と下定盤４００との間に形成される隙間に、キャリア５００が配置される。ディスク状のガラス基板１は、このキャリア５００に複数枚保持される。なお、キャリア５００の詳細構造については、後述する。 The upper polishing pad 310 and the lower polishing pad 410 are processing tools for polishing both main surfaces of the glass substrate 1. The upper surface plate 300 and the lower surface plate 400 rotate in directions opposite to each other with respect to the revolution direction of the carrier 500. Carrier 500 is arranged in a gap formed between upper surface plate 300 and lower surface plate 400. A plurality of disk-shaped glass substrates 1 are held by the carrier 500. The detailed structure of the carrier 500 will be described later.
　第２ポリッシュ工程（ステップＳ３４）において、上側研磨パッド３１０および下側研磨パッド４１０の表面の洗浄が行なわれてもよい。上側研磨パッド３１０および下側研磨パッドの表面の洗浄は、研磨工程（ステップＳ３０）中の任意の工程において行なわれてもよく、研磨工程（ステップＳ３０）中の任意の工程間に行なわれてもよく、または、研磨工程（ステップＳ３０）の終了後に行なわれてもよい。 In the second polishing step (step S34), the surfaces of the upper polishing pad 310 and the lower polishing pad 410 may be cleaned. The cleaning of the surfaces of the upper polishing pad 310 and the lower polishing pad may be performed in any step in the polishing step (step S30), or may be performed in any step in the polishing step (step S30). Alternatively, it may be performed after the polishing process (step S30) ends.
　ガラス基板１の両主表面を一回または複数回研磨加工した後に、両面研磨装置２０００において上側研磨パッド３１０および下側研磨パッド４１０の表面の洗浄が行なわれる。上側研磨パッド３１０および下側研磨パッド４１０の表面は、一回もしくは複数回の研磨を行なう毎に定期的に洗浄されてもよく、または、不定期的に洗浄されてもよい。 After both main surfaces of the glass substrate 1 are polished once or a plurality of times, the surfaces of the upper polishing pad 310 and the lower polishing pad 410 are cleaned in the double-side polishing apparatus 2000. The surfaces of the upper polishing pad 310 and the lower polishing pad 410 may be periodically cleaned each time one or more polishings are performed, or may be cleaned irregularly.
　（化学強化工程）
　ガラス基板が洗浄された後、化学強化処理液にガラス基板を浸漬することによって、ガラス基板の両主表面に化学強化層を形成する（ステップＳ４０）。ガラス基板１が洗浄された後、３００℃に加熱された硝酸カリウム（７０％）と硝酸ナトリウム（３０％）との混合用液などの化学強化処理液中に、ガラス基板１を３０分間程度浸漬することによって、化学強化を行なう。 (Chemical strengthening process)
After the glass substrate is washed, the chemical strengthening layer is formed on both main surfaces of the glass substrate by immersing the glass substrate in the chemical strengthening treatment liquid (step S40). After the glass substrate 1 is cleaned, the glass substrate 1 is immersed for about 30 minutes in a chemical strengthening treatment solution such as a mixture solution of potassium nitrate (70%) and sodium nitrate (30%) heated to 300 ° C. By doing so, chemical strengthening is performed.
　ガラス基板１に含まれるリチウムイオン、ナトリウムイオン等のアルカリ金属イオンは、これらのイオンに比べてイオン半径の大きなカリウムイオン等のアルカリ金属イオンによって置換される（イオン交換法）。 The alkali metal ions such as lithium ions and sodium ions contained in the glass substrate 1 are replaced by alkali metal ions such as potassium ions having a larger ion radius than these ions (ion exchange method).
　イオン半径の違いによって生じる歪みより、イオン交換された領域に圧縮応力が発生し、ガラス基板１の両主表面が強化される。たとえば、ガラス基板１の両主表面において、ガラス基板１表面から約５μｍまでの範囲に化学強化層を形成し、ガラス基板１の剛性を向上させてもよい。以上のようにして、図１に示すガラス基板１に相当するガラス基板が得られる。 Compressive stress is generated in the ion-exchanged region due to strain caused by the difference in ion radius, and both main surfaces of the glass substrate 1 are strengthened. For example, on both the main surfaces of the glass substrate 1, a chemical strengthening layer may be formed in a range from the surface of the glass substrate 1 to about 5 μm to improve the rigidity of the glass substrate 1. As described above, a glass substrate corresponding to the glass substrate 1 shown in FIG. 1 is obtained.
　ガラス基板１に対しては、両主表面上における取り代が０．１μｍ以上０．５μｍ以下のポリッシュ処理がさらに施されてもよい。化学強化工程を経た後にガラス基板１の主表面上に残留している付着物が除去されることによって、ガラス基板１を用いて製造される磁気ディスクにヘッドクラッシュが発生することが低減される。また、ポリッシュ処理における両主表面上の取り代を０．１μｍ以上０．５μｍ以下とすることによって、化学強化処理によって発生した応力の不均一性が表面に現れることもなくなる。本実施の形態におけるガラス基板の製造方法としては、以上のように構成される。 The glass substrate 1 may be further subjected to a polishing treatment with a machining allowance on both main surfaces of 0.1 μm to 0.5 μm. By removing the deposits remaining on the main surface of the glass substrate 1 after the chemical strengthening step, occurrence of head crashes in a magnetic disk manufactured using the glass substrate 1 is reduced. Further, by setting the machining allowance on both main surfaces in the polishing process to be 0.1 μm or more and 0.5 μm or less, the unevenness of stress generated by the chemical strengthening process does not appear on the surface. The manufacturing method of the glass substrate in the present embodiment is configured as described above.
　なお、第１ポリッシュ工程（粗研磨）と第２ポリッシュ工程（精密研磨）との間に、化学強化工程を施してもかまわない。 It should be noted that a chemical strengthening step may be performed between the first polishing step (rough polishing) and the second polishing step (precision polishing).
　（洗浄工程）
　次に、ガラス基板は洗浄される（ステップＳ５０）。ガラス基板の両主表面が洗剤、純水、オゾン、ＩＰＡ（イソプロピルアルコール）、またはＵＶ（ultraviolet）オゾンなどによって洗浄されることによって、ガラス基板の両主表面に付着した付着物が除去される。 (Washing process)
Next, the glass substrate is cleaned (step S50). By cleaning the two main surfaces of the glass substrate with detergent, pure water, ozone, IPA (isopropyl alcohol), UV (ultraviolet) ozone, or the like, the deposits attached to the two main surfaces of the glass substrate are removed.
　その後、ガラス基板１の表面上の付着物の数が、光学式欠陥検査装置等を用いて検査される。 Thereafter, the number of deposits on the surface of the glass substrate 1 is inspected using an optical defect inspection apparatus or the like.
　（磁気薄膜形成工程）
　化学強化処理が完了したガラス基板（図１に示すガラス基板１に相当）の両主表面（またはいずれか一方の主表面）に対し、磁性膜が形成されることにより、磁気薄膜層２が形成される。磁気薄膜層は、Ｃｒ合金からなる密着層、ＣｏＦｅＺｒ合金からなる軟磁性層、Ｒｕからなる配向制御下地層、ＣｏＣｒＰｔ合金からなる垂直磁気記録層、Ｃ系からなる保護層、およびＦ系からなる潤滑層が順次成膜されることによって形成される。磁気薄膜層の形成によって、図２に示す磁気ディスク１０に相当する垂直磁気記録ディスクを得ることができる。 (Magnetic thin film formation process)
The magnetic thin film layer 2 is formed by forming a magnetic film on both main surfaces (or one of the main surfaces) of the glass substrate (corresponding to the glass substrate 1 shown in FIG. 1) that has been subjected to the chemical strengthening treatment. Is done. The magnetic thin film layer includes an adhesion layer made of a Cr alloy, a soft magnetic layer made of a CoFeZr alloy, an orientation control underlayer made of Ru, a perpendicular magnetic recording layer made of a CoCrPt alloy, a protective layer made of a C system, and a lubrication made of an F system. It is formed by sequentially depositing layers. By forming the magnetic thin film layer, a perpendicular magnetic recording disk corresponding to the magnetic disk 10 shown in FIG. 2 can be obtained.
　本実施の形態における磁気ディスクは、磁気薄膜層から構成される垂直磁気ディスクの一例である。磁気ディスクは、いわゆる面内磁気ディスクとして磁性層等から構成されてもよい。 The magnetic disk in the present embodiment is an example of a perpendicular magnetic disk composed of a magnetic thin film layer. The magnetic disk may be composed of a magnetic layer or the like as a so-called in-plane magnetic disk.
　（キャリア５００）
　次に、図５から図７を参照して、上述した研削／研磨工程中の第２ポリッシュ工程において用いられる両面研磨装置２０００に採用されるキャリア５００の詳細構造について説明する。図５は、本実施の形態におけるキャリア５００を示す平面図、図６は、本実施の形態におけるキャリアの寸法関係を示す平面図、図７は、ガラス基板１の平面図である。 (Carrier 500)
Next, the detailed structure of the carrier 500 employed in the double-side polishing apparatus 2000 used in the second polishing step in the above-described grinding / polishing step will be described with reference to FIGS. FIG. 5 is a plan view showing a carrier 500 in the present embodiment, FIG. 6 is a plan view showing a dimensional relationship of the carrier in the present embodiment, and FIG. 7 is a plan view of the glass substrate 1.
　図５を参照して、本実施の形態におけるキャリア５００は、円盤形状の本体５１０を有し、厚さは、約０．３０ｍｍ～２．２ｍｍであり、保持するガラス基板１の厚さよりも薄い厚さが選択される。キャリア５００の直径は、約４３０ｍｍである。本体５１０には、アラミド繊維、ＦＲＰ（ガラスエポキシ）、ＰＣ（ポリカーボネート）等が用いられる。 Referring to FIG. 5, carrier 500 in the present embodiment has a disc-shaped main body 510, and the thickness is about 0.30 mm to 2.2 mm, which is thinner than the thickness of glass substrate 1 to be held. The thickness is selected. The diameter of the carrier 500 is about 430 mm. For the main body 510, aramid fiber, FRP (glass epoxy), PC (polycarbonate), or the like is used.
　キャリア５００には、ガラス基板１を保持する貫通保持孔５２０が２２箇所設けられている。本実施の形態では、貫通保持孔５２０は、２重の環状となるように配列され、内環状ラインｒ１上に、貫通保持孔５２０Ｐが等間隔で８個配列され、外環状ラインｒ２上に、貫通保持孔５２０Ｐが等間隔で１４個配列されている。貫通保持孔５２０の直径は、約６６．５ｍｍである。 The carrier 500 is provided with 22 through-holding holes 520 for holding the glass substrate 1. In the present embodiment, the through-holding holes 520 are arranged in a double ring shape, eight through-holding holes 520P are arranged at equal intervals on the inner annular line r1, and on the outer annular line r2. Fourteen through-holding holes 520P are arranged at equal intervals. The diameter of the through-holding hole 520 is about 66.5 mm.
　ここで、図６を参照して、本実施の形態におけるキャリア５００は、ガラス基板１を保持しないガラス基板非保持領域Ｓを有している。このガラス基板非保持領域Ｓは、ガラス基板１の直径をＤｍｍ（図７参照）とした場合に、キャリア５００の中心位置Ｃ１から半径Ｄｍｍで囲まれた円領域を含む領域である。この半径Ｄｍｍで囲まれた円領域には、貫通保持孔５２０の中心は設けられていない。 Here, referring to FIG. 6, carrier 500 in the present embodiment has glass substrate non-holding region S that does not hold glass substrate 1. The glass substrate non-holding region S is a region including a circular region surrounded by a radius Dmm from the center position C1 of the carrier 500 when the diameter of the glass substrate 1 is Dmm (see FIG. 7). The center of the through-holding hole 520 is not provided in the circular region surrounded by the radius Dmm.
　キャリア５００のガラス基板非保持領域Ｓの中心位置Ｃ１を含む一部の領域は、他の領域よりもキャリア５００の厚みが薄く設けられている。この厚みが薄く設けられている領域は、円形状である必要はない。 In some regions including the center position C1 of the glass substrate non-holding region S of the carrier 500, the thickness of the carrier 500 is thinner than other regions. The area where the thickness is thin need not be circular.
　本実施の形態では、ガラス基板１の直径Ｄは６５ｍｍであることから、ガラス基板非保持領域Ｓは、半径６５ｍｍの円で囲まれた領域を含む。 In the present embodiment, since the diameter D of the glass substrate 1 is 65 mm, the glass substrate non-holding region S includes a region surrounded by a circle having a radius of 65 mm.
　本実施の形態における両面研磨装置２０００は、上定盤３００と下定盤４００との間に、５枚のキャリア５００を環状に配置する。キャリア５００の外周面には、ギヤが設けられているが、ギヤの図示は省略する。また、キャリア５００の半径は、ギヤの歯先円で測定した場合の寸法を意味する。 In the double-side polishing apparatus 2000 in the present embodiment, five carriers 500 are annularly arranged between the upper surface plate 300 and the lower surface plate 400. A gear is provided on the outer peripheral surface of the carrier 500, but the illustration of the gear is omitted. Further, the radius of the carrier 500 means a dimension when measured with a gear tip circle.
　ここで、図８を参照して、キャリア５００の中心位置Ｃ１に、中心位置が重なる貫通保持孔５２０を設けた場合の両面研磨装置２０００について説明する。図８は、第１貫通保持孔５２０Ｃをキャリア５００の中心に設けた場合のキャリア５００を示している。 Here, with reference to FIG. 8, a description will be given of a double-side polishing apparatus 2000 in which a through-holding hole 520 whose center position overlaps is provided at the center position C1 of the carrier 500. FIG. 8 shows the carrier 500 when the first through-holding hole 520 </ b> C is provided at the center of the carrier 500.
　この図８に示すキャリア５００を用いて、両面研磨装置２０００によりガラス基板１の両面研磨を行なった場合には、図８に示すように、両面研磨装置２０００の駆動時には、下側研磨パッド４１０の中帯領域Ｂ１付近はキャリア５００およびガラス基板１の実質的な通過時間が、外周領域Ｂ２および内周領域Ｂ３に比較して長い。その結果、外周領域Ｂ２および内周領域Ｂ３と中帯領域Ｂ１との間において、下側研磨パッド４１０の摩耗状態に違い（偏摩耗）が生じることとなる。この偏摩耗が原因となり、ガラス基板１の平坦度にバラツキが発生する。このことは、下側研磨パッド４１０に限らず、上側研磨パッド３１０においても同様の現象が生じる。 When double-side polishing of the glass substrate 1 is performed by the double-side polishing apparatus 2000 using the carrier 500 shown in FIG. 8, when the double-side polishing apparatus 2000 is driven, the lower polishing pad 410 is driven as shown in FIG. In the vicinity of the middle belt region B1, the substantial transit time of the carrier 500 and the glass substrate 1 is longer than that of the outer peripheral region B2 and the inner peripheral region B3. As a result, a difference in wear state of the lower polishing pad 410 (partial wear) occurs between the outer peripheral region B2, the inner peripheral region B3, and the middle belt region B1. Due to this uneven wear, the flatness of the glass substrate 1 varies. This occurs not only in the lower polishing pad 410 but also in the upper polishing pad 310.
　一方、図５に示した本実施の形態おけるキャリア５００は、キャリア５００の中心位置Ｃ１に非貫通保持孔形成領域Ｓを設けている。 On the other hand, the carrier 500 in the present embodiment shown in FIG. 5 is provided with a non-through holding hole forming region S at the center position C1 of the carrier 500.
　これにより、両面研磨装置２０００によりガラス基板１の両面研磨を行なった場合でも、ガラス基板１が中帯領域Ｂ１を通過する頻度を低減することが可能となる。 Thereby, even when the double-side polishing of the glass substrate 1 is performed by the double-side polishing apparatus 2000, the frequency with which the glass substrate 1 passes through the middle band region B1 can be reduced.
　その結果、上側研磨パッド３１０および下側研磨パッド４１０の外周領域Ｂ２および内周領域Ｂ３と中帯領域Ｂ１との間において、上側研磨パッド３１０および下側研磨パッド４１０の摩耗状態に違い（偏摩耗）が生じることを抑制することが可能となる。 As a result, the wear state of the upper polishing pad 310 and the lower polishing pad 410 differs between the outer peripheral region B2 and inner peripheral region B3 of the upper polishing pad 310 and the lower polishing pad 410 and the middle belt region B1 (partial wear). ) Can be suppressed.
　（実施例）
　上記情報記録媒体用ガラス基板の製造方法の各実施例および比較例について以下説明する。以下に示す各実施例および比較例においては、図３に示すＳ３３の「第１ポリッシュ工程（粗研磨）」までは、上記した説明のとおり実施した。ガラス基板の枚数は、各実施例では合計１１０枚、比較例では、合計１１５枚である。 (Example)
Examples and comparative examples of the method for producing the glass substrate for information recording medium will be described below. In each of the following examples and comparative examples, the processes up to the “first polishing step (rough polishing)” of S33 shown in FIG. 3 were performed as described above. The total number of glass substrates is 110 in each example and 115 in the comparative example.
　実施例１には、図５に示したキャリア５００を用いた。実施例２には、図９に示すように、キャリアの中心位置Ｃ１に、貫通保持孔５２０よりも直径が大きい、８０ｍｍの直径を有する補助貫通孔５２０Ｍを１つ設けたキャリア５００を用いた。補助貫通孔５２０Ｍは、ガラス基板１の直径と比較して直径が大きすぎるため、この補助貫通孔５２０Ｍを、ガラス基板１を保持する貫通保持孔５２０として用いることはできない。補助貫通孔の外周には、加工中に研磨パッドが傷つかないよう、任意の面取り処理を行ってもよい。 In Example 1, the carrier 500 shown in FIG. 5 was used. In Example 2, as shown in FIG. 9, a carrier 500 having one auxiliary through hole 520M having a diameter of 80 mm, which is larger than the through holding hole 520, at the center position C1 of the carrier was used. Since the auxiliary through hole 520M has a diameter that is too large compared to the diameter of the glass substrate 1, the auxiliary through hole 520M cannot be used as the through holding hole 520 for holding the glass substrate 1. Arbitrary chamfering treatment may be performed on the outer periphery of the auxiliary through hole so that the polishing pad is not damaged during processing.
　比較例１として、キャリア５００の中心位置Ｃ１に、中心位置が一致する貫通保持孔５２０を有するキャリア５００を用いた。 As Comparative Example 1, a carrier 500 having a through-holding hole 520 whose center position coincides with the center position C1 of the carrier 500 was used.
　なお、図１０に示すように、補助貫通孔５２０Ｍと同等の開口面積を有するように、貫通保持孔５２０の直径よりも小さい直径の補助貫通孔５２０Ｍを複数（図１０では３つ）設ける構成を採用してもよい。この補助貫通孔５２０Ｍの直径は、貫通保持孔５２０の直径よりも小さいため、ガラス基板１を保持する貫通保持孔５２０として用いることはできない。補助貫通孔の外周には、加工中に研磨パッドが傷つかないよう、任意の面取り処理を行ってもよい。 As shown in FIG. 10, a configuration is provided in which a plurality (three in FIG. 10) of auxiliary through holes 520M having a diameter smaller than the diameter of the through holding hole 520 are provided so as to have an opening area equivalent to that of the auxiliary through hole 520M. It may be adopted. Since the diameter of the auxiliary through hole 520M is smaller than the diameter of the through holding hole 520, it cannot be used as the through holding hole 520 for holding the glass substrate 1. Arbitrary chamfering treatment may be performed on the outer periphery of the auxiliary through hole so that the polishing pad is not damaged during processing.
　なお、各実施例および各比較例においては、第２ポリッシュ工程で用いられる両面研磨装置により、予め本試験で使用するガラス基板とは別のガラス基板を用いた事前加工が行なわれ、上下研磨パッドが固有の傾向を示す条件を整えた上で第２ポリッシュ工程を実施した。具体的には、本試験を行なう前に、各実施例および各比較例で用いられているキャリアを使用し、それぞれ累計加工時間が略合計４０時間となるよう、本試験で使用する両面研磨装置を用いて事前のガラス基板加工を行なった。事前加工には上記Ｓ３３工程までの手順で作成されるガラス基板と同様のガラス基板を使用した。事前加工により、その実施例・比較例のキャリアに固有である、研磨パッドへの摩耗が見られるようになる。 In each example and each comparative example, the double-side polishing apparatus used in the second polishing step is preliminarily processed using a glass substrate different from the glass substrate used in this test, and the upper and lower polishing pads are used. The second polishing step was carried out after adjusting the conditions showing the inherent tendency. Specifically, before carrying out this test, the double-side polishing apparatus used in this test is used so that the carrier used in each example and each comparative example is used and the total machining time is approximately 40 hours in total. The glass substrate was processed in advance using The glass substrate similar to the glass substrate created in the procedure up to the above-mentioned step S33 was used for the pre-processing. By the pre-processing, the wear on the polishing pad, which is specific to the carrier of the example and the comparative example, can be seen.
　（ガラス基板の端面計測）
　図１１に、実施例１，実施例２および比較例１における評価結果を示す。実施例１，実施例２および比較例１によって得られたガラス基板に対して、Phase　Shift　Technology社製のOptiflat　ＩＩを使用してガラス基板の表面形状を計測した。 (End measurement of glass substrate)
In FIG. 11, the evaluation result in Example 1, Example 2, and the comparative example 1 is shown. For the glass substrates obtained in Example 1, Example 2 and Comparative Example 1, the surface shape of the glass substrate was measured using Optiflat II manufactured by Phase Shift Technology.
　計測結果の傾き補正を行なった後、ガラス基板面内の最低点の高さと最高点の高さとの差を解析した。この解析結果の値が、０．６μｍ以下のものを良品と判定した。各実施例および比較例で、それぞれガラス基板を５０枚を計測し、良品の割合を調査した。解析結果が、９０％未満のものを「Ｃ」と評価して不合格とし、９０％以上のものを「Ａ」と評価して合格とした。特に、解析結果が、９４％以上のものを「ＡＡ」と評価して合格とした。 After correcting the inclination of the measurement result, the difference between the height of the lowest point and the height of the highest point in the glass substrate surface was analyzed. A value of the analysis result of 0.6 μm or less was determined as a non-defective product. In each example and comparative example, 50 glass substrates were measured, respectively, and the ratio of non-defective products was investigated. An analysis result of less than 90% was evaluated as “C” and rejected, and 90% or more was evaluated as “A” and passed. In particular, an analysis result of 94% or more was evaluated as “AA” and passed.
　解析の結果、比較例１では平坦度が悪く、実施例１および実施例２では、平坦度が良好な結果となった。比較例１では、ガラス基板の通過に伴い、定盤の中帯領域のやや広い範囲でパッド表面が摩耗しており、研磨中のガラス基板が定盤に対する平行を保てず、平坦度の悪化につながったと考えられる。 As a result of analysis, the flatness was poor in Comparative Example 1, and the flatness was good in Examples 1 and 2. In Comparative Example 1, with the passage of the glass substrate, the pad surface is worn in a slightly wide range of the middle band region of the surface plate, and the glass substrate being polished cannot keep parallel to the surface plate, and the flatness deteriorates. It is thought that led to.
　一方、実施例１および実施例２は、定盤の中帯領域での偏摩耗が抑制され、「第２ポリッシュ工程（精密研磨）（Ｓ３４）」によるガラス基板の平坦度の悪化が抑制されたものと考えられる。特に、実施例２では、中帯領域をキャリア５００が通過する頻度についても低減しているため、これによる偏摩耗が抑制されるとともに、平坦度悪化の改善が抑制されたものと考えられる。 On the other hand, in Example 1 and Example 2, uneven wear in the middle band region of the surface plate was suppressed, and deterioration of the flatness of the glass substrate due to the “second polishing step (precision polishing) (S34)” was suppressed. It is considered a thing. In particular, in Example 2, since the frequency with which the carrier 500 passes through the middle band region is also reduced, it is considered that uneven wear due to this is suppressed, and improvement in flatness deterioration is suppressed.
　さらに、上記実施例１－２、および、比較例１によって得られたガラス基板に対して、図３に示す、化学強化工程（Ｓ４０）、洗浄工程（Ｓ５０）、および磁気薄膜形成工程（Ｓ６０）を実施し、情報記録媒体を得た。 Furthermore, the chemical strengthening step (S40), the cleaning step (S50), and the magnetic thin film forming step (S60) shown in FIG. 3 for the glass substrates obtained in Example 1-2 and Comparative Example 1 above. The information recording medium was obtained.
　この情報記録媒体を、ハードドライブに組み込み、リードライト試験を行なった。比較例１と比較し、実施例１および実施例２では基準値をクリアするハードドライブの割合が高かった。特に、実施例２では基準値をクリアするハードドライブの割合が高かった。 This information recording medium was incorporated into a hard drive and a read / write test was conducted. Compared to Comparative Example 1, in Examples 1 and 2, the percentage of hard drives that cleared the reference value was high. In particular, in Example 2, the ratio of hard drives that cleared the reference value was high.
　なお、上記実施例は、第２ポリッシュ工程（精密研磨）Ｓ３４に本発明を適用した場合について説明しているが、第１ポリッシュ工程（粗研磨）Ｓ３３に本発明を適用した場合であっても、または、第１ポリッシュ工程（粗研磨）Ｓ３３および第２ポリッシュ工程（精密研磨）Ｓ３４の両工程に本発明を適用した場合であっても、同様の作用効果を得ることが可能である。 The above embodiment describes the case where the present invention is applied to the second polishing step (precise polishing) S34. However, even if the present invention is applied to the first polishing step (rough polishing) S33. Alternatively, even when the present invention is applied to both the first polishing step (rough polishing) S33 and the second polishing step (precision polishing) S34, the same effects can be obtained.
　以上のように本発明の実施の形態および実施例について説明を行なったが、今回開示された実施の形態および実施例はすべての点で例示であって、制限的なものではないと考えられるべきである。この発明の範囲は上記した説明ではなくて請求の範囲によって示され、請求の範囲と均等の意味、および範囲内でのすべての変更が含まれることが意図される。 Although the embodiments and examples of the present invention have been described above, the embodiments and examples disclosed this time are illustrative in all respects and should not be considered as restrictive. It is. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
　１Ａ　表主表面、１Ｂ　裏主表面、１Ｃ　内周端面、１Ｄ　外周端面、１Ｈ　孔、２　磁気薄膜層、１０　磁気ディスク、３００　上定盤、３１０　上側研磨パッド、３１０ｇ，４１０ｇ　溝、４００　下定盤、４１０　下側研磨パッド、５００　キャリア、５１０　本体、５２０　貫通保持孔、５２０Ｍ　補助貫通孔、２０００　両面研磨装置。 1A front main surface, 1B back main surface, 1C inner peripheral end surface, 1D outer peripheral end surface, 1H hole, 2 magnetic thin film layer, 10 magnetic disk, 300 upper surface plate, 310 upper polishing pad, 310g, 410g groove, 400 lower surface plate, 410 lower polishing pad, 500 carrier, 510 main body, 520 through holding hole, 520M auxiliary through hole, 2000 double-side polishing machine.

Claims (5)

  1. 　円形ディスク形状のガラス基板の主表面に磁気薄膜層が形成される情報記録媒体用ガラス基板の製造方法であって、
    　遊星歯車機構を備えた両面研磨装置を用いて前記ガラス基板の主表面を、研磨剤を供給しながら研磨する表面研磨工程を有し、
    　前記両面研磨装置は、
    　前記ガラス基板の上側に位置し、前記ガラス基板側に上側研磨パッドを有する上定盤と、
    　前記ガラス基板の下側に位置し、前記ガラス基板側に下側研磨パッドを有する下定盤と、
    　前記ガラス基板を保持する貫通保持孔が複数設けられ、前記上側研磨パッドと前記下側研磨パッドとにより挟み込まれるとともに、前記遊星歯車機構により所定の回転運動を行なう円盤状のキャリアと、を備え、
    　前記キャリアは、前記ガラス基板を保持しないガラス基板非保持領域を有し、
    　前記ガラス基板非保持領域は、前記ガラス基板の直径をＤｍｍとした場合に、前記キャリアの中心位置から半径Ｄｍｍで囲まれた円領域を含む、情報記録媒体用ガラス基板の製造方法。     A method for producing a glass substrate for an information recording medium in which a magnetic thin film layer is formed on the main surface of a circular disk-shaped glass substrate,
    A surface polishing step of polishing the main surface of the glass substrate using a double-side polishing apparatus equipped with a planetary gear mechanism while supplying an abrasive;
    The double-side polishing apparatus includes:
    Located on the upper side of the glass substrate, an upper surface plate having an upper polishing pad on the glass substrate side,
    Located on the lower side of the glass substrate, a lower surface plate having a lower polishing pad on the glass substrate side,
    A plurality of through-holding holes for holding the glass substrate, and a disc-shaped carrier that is sandwiched between the upper polishing pad and the lower polishing pad and performs a predetermined rotational movement by the planetary gear mechanism,
    The carrier has a glass substrate non-holding region that does not hold the glass substrate,
    The glass substrate non-holding region includes a circular region surrounded by a radius Dmm from the center position of the carrier, where the diameter of the glass substrate is Dmm, and a method for manufacturing a glass substrate for an information recording medium.
  2. 　前記ガラス基板非保持領域において、前記キャリアの中心位置から半径Ｄｍｍで囲まれた円領域には、前記貫通保持孔の中心は設けられていない、請求項１に記載の情報記録媒体用ガラス基板の製造方法。 2. The glass substrate for an information recording medium according to claim 1, wherein, in the glass substrate non-holding region, a center of the through-holding hole is not provided in a circular region surrounded by a radius Dmm from the center position of the carrier. Production method.
  3. 　前記ガラス基板非保持領域は、前記ガラス基板を保持することができない補助貫通孔を有する、請求項１に記載の情報記録媒体用ガラス基板の製造方法。 The method for producing a glass substrate for an information recording medium according to claim 1, wherein the glass substrate non-holding region has an auxiliary through-hole that cannot hold the glass substrate.
  4. 　前記補助貫通孔の外周には、面取り処理が行なわれる、請求項３に記載の情報記録媒体用ガラス基板の製造方法。 The method for manufacturing a glass substrate for an information recording medium according to claim 3, wherein a chamfering process is performed on an outer periphery of the auxiliary through hole.
  5. 　ガラス基板と、
    　前記ガラス基板の主表面に形成された磁気薄膜層と、
    を備える情報記録媒体であって、
    　前記ガラス基板は、
    　円形ディスク形状の前記ガラス基板の主表面に磁気薄膜層が形成される情報記録媒体用ガラス基板の製造方法で製造され、
    　前記情報記録媒体用ガラス基板の製造方法は、
    　遊星歯車機構を備えた両面研磨装置を用いて前記ガラス基板の主表面を、研磨剤を供給しながら研磨する表面研磨工程を有し、
    　前記両面研磨装置は、
    　前記ガラス基板の上側に位置し、前記ガラス基板側に上側研磨パッドを有する上定盤と、
    　前記ガラス基板の下側に位置し、前記ガラス基板側に下側研磨パッドを有する下定盤と、
    　前記ガラス基板を保持する貫通保持孔が複数設けられ、前記上側研磨パッドと前記下側研磨パッドとにより挟み込まれるとともに、前記遊星歯車機構により所定の回転運動を行なう円盤状のキャリアと、を備え、
    　前記キャリアは、前記ガラス基板を保持しないガラス基板非保持領域を有し、
    　前記ガラス基板非保持領域は、前記ガラス基板の直径をＤｍｍとした場合に、前記キャリアの中心位置から半径Ｄｍｍで囲まれた円領域を含む、情報記録媒体。     A glass substrate;
    A magnetic thin film layer formed on the main surface of the glass substrate;
    An information recording medium comprising:
    The glass substrate is
    Produced by a method for producing a glass substrate for information recording media in which a magnetic thin film layer is formed on the main surface of the glass substrate having a circular disk shape
    The manufacturing method of the glass substrate for information recording medium,
    A surface polishing step of polishing the main surface of the glass substrate using a double-side polishing apparatus equipped with a planetary gear mechanism while supplying an abrasive;
    The double-side polishing apparatus includes:
    Located on the upper side of the glass substrate, an upper surface plate having an upper polishing pad on the glass substrate side,
    Located on the lower side of the glass substrate, a lower surface plate having a lower polishing pad on the glass substrate side,
    A plurality of through-holding holes for holding the glass substrate, and a disc-shaped carrier that is sandwiched between the upper polishing pad and the lower polishing pad and performs a predetermined rotational movement by the planetary gear mechanism,
    The carrier has a glass substrate non-holding region that does not hold the glass substrate,
    The glass substrate non-holding area is an information recording medium including a circular area surrounded by a radius Dmm from the center position of the carrier, where the diameter of the glass substrate is Dmm.
PCT/JP2013/056078 2012-03-30 2013-03-06 Manufacturing method for glass substrate for information recording medium, and information recording medium WO2013146131A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11254292A (en) * 1998-03-11 1999-09-21 Super Silicon Kenkyusho:Kk Method and device for conditioning abrasive cloth
JP2007015105A (en) * 2006-09-25 2007-01-25 Hoya Corp Polishing carrier, polishing method, and manufacturing method of substrate for information recording medium
JP2012033265A (en) * 2011-11-14 2012-02-16 Asahi Glass Co Ltd Glass substrate for magnetic recording medium and manufacturing method thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11254292A (en) * 1998-03-11 1999-09-21 Super Silicon Kenkyusho:Kk Method and device for conditioning abrasive cloth
JP2007015105A (en) * 2006-09-25 2007-01-25 Hoya Corp Polishing carrier, polishing method, and manufacturing method of substrate for information recording medium
JP2012033265A (en) * 2011-11-14 2012-02-16 Asahi Glass Co Ltd Glass substrate for magnetic recording medium and manufacturing method thereof

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