WO2012001884A1 - Method for manufacturing glass substrate for information recording media - Google Patents

Method for manufacturing glass substrate for information recording media Download PDF

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Publication number
WO2012001884A1
WO2012001884A1 PCT/JP2011/003224 JP2011003224W WO2012001884A1 WO 2012001884 A1 WO2012001884 A1 WO 2012001884A1 JP 2011003224 W JP2011003224 W JP 2011003224W WO 2012001884 A1 WO2012001884 A1 WO 2012001884A1
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WO
WIPO (PCT)
Prior art keywords
base plate
tir
information recording
glass base
less
Prior art date
Application number
PCT/JP2011/003224
Other languages
French (fr)
Japanese (ja)
Inventor
典子 島津
Original Assignee
コニカミノルタオプト株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by コニカミノルタオプト株式会社 filed Critical コニカミノルタオプト株式会社
Publication of WO2012001884A1 publication Critical patent/WO2012001884A1/en

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Classifications

    • 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
    • B24B37/04—Lapping machines or devices; Accessories designed for working plane surfaces
    • B24B37/042—Lapping machines or devices; Accessories designed for working plane surfaces operating processes therefor
    • 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
    • B24B37/04—Lapping machines or devices; Accessories designed for working plane surfaces
    • B24B37/07—Lapping machines or devices; Accessories designed for working plane surfaces characterised by the movement of the work or lapping tool
    • B24B37/08—Lapping machines or devices; Accessories designed for working plane surfaces characterised by the movement of the work or lapping tool for double side lapping
    • 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
    • B24B57/00—Devices for feeding, applying, grading or recovering grinding, polishing or lapping agents
    • B24B57/02—Devices for feeding, applying, grading or recovering grinding, polishing or lapping agents for feeding of fluid, sprayed, pulverised, or liquefied grinding, polishing or lapping agents
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C19/00—Surface treatment of glass, not in the form of fibres or filaments, by mechanical means
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
    • C03C3/095—Glass compositions containing silica with 40% to 90% silica, by weight containing rare earths
    • 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
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
    • G11B5/739—Magnetic recording media substrates
    • G11B5/73911—Inorganic substrates
    • G11B5/73921—Glass or ceramic substrates

Definitions

  • the present invention relates to a method for producing a glass substrate for an information recording medium.
  • the glass substrate for information recording media is generally manufactured through a lapping (grinding) process or a polishing process.
  • grinding provided in the grinding apparatus by using a grinding liquid using pure water as a solvent or by using a grinding apparatus having a function of separating polishing sludge components such as polishing scraps. Clogging of the grindstone as a member is prevented (see Patent Document 1).
  • the present invention provides a glass for an information recording medium that is less likely to cause clogging of a grinding member and that can provide a glass substrate for an information recording medium having a good TIR by setting the TIR of the glass base plate after the lapping step to a certain value or less It aims at providing the manufacturing method of a board
  • One aspect of the present invention is a method for manufacturing a glass substrate for an information recording medium, which includes a lapping process in which a surface of a glass base plate is lapped using a grinding apparatus and a grinding liquid, and the grinding is performed in the lapping process.
  • the TIR in the circumferential direction is 0.75 ⁇ r1 from the center of the glass base plate. (2 ⁇ r2 + r1) / 3 from the center of the glass base plate when the outer periphery TIR measured for one track is 1.4 ⁇ m or less, the radius of the glass base plate is r1, and the radius of the through hole of the glass base plate is r2.
  • the glass base plate is lapped so that the inner circumference TIR obtained by measuring the TIR in the circumferential direction at a position of 1 at a position of 0.7 ⁇ m or less.
  • (A) is a plan view of the polishing apparatus when the upper polishing dish is moved to the left side
  • (b) is a plan view of the polishing apparatus when the upper polishing dish is overlaid on the lower polishing dish
  • (c) ) Is a plan view of the polishing apparatus when the upper polishing dish moves to the right side. It is a chart showing the measured values of the inner circumference TIR and the outer circumference TIR after the second lapping process and after the precision polishing process, for Examples and Comparative Examples. It is explanatory drawing at the time of explaining inner periphery TIR and outer periphery TIR.
  • the grinding fluid contains calcium or magnesium
  • an insoluble metal salt is formed by the calcium or magnesium and the surfactant in the grinding fluid, and clogging of grinding members such as grindstones and diamond sheets.
  • the calcium component or magnesium is contained in the grinding fluid during lapping. The component comes out, and an insoluble metal salt is generated by the calcium component or the magnesium component and the surfactant in the grinding fluid, and as a result, the grinding member may be clogged as described above. In such a case, even if a conventional grinding device having a sludge separation function is used, it is difficult to prevent clogging of the grinding member only by separating the generated sludge.
  • TIR refers to an index representing the flatness (waviness) of the glass substrate or glass base plate for an information recording medium, and is the distance between the highest point and the lowest point from the least square plane of the evaluation surface (substrate surface). Total.
  • the outer periphery TIR is 0. 0 from the center of the glass substrate 10 a or the glass base plate 10 when the radius of the glass substrate 10 a for information recording medium or the glass base plate 10 is r1.
  • the TIR in the circumferential direction is measured for one track at a position satisfying 75 ⁇ r1.
  • the inner circumference TIR is from the center of the glass substrate 10a or the glass base plate 10 when the radius of the information recording medium glass substrate 10a or the glass base plate 10 is r1 and the radius of the through hole 10b is r2.
  • the TIR in the circumferential direction was measured for one track at a position satisfying (2 ⁇ r2 + r1) / 3.
  • FIG. 1 is a perspective view of a glass substrate for an information recording medium of one embodiment manufactured by the manufacturing method of the present invention
  • FIG. 2 is a process diagram of one embodiment of the manufacturing method of the present invention.
  • the method of manufacturing the glass substrate for information recording medium includes a disk processing step, a lapping step, a rough polishing step, a chemical strengthening step, a precision (final) polishing step, and a final cleaning step.
  • the glass substrate 10a for information recording media is manufactured through these steps.
  • the glass material to be used is SiO 2 : 55 to 75% by mass, Al 2 O 3 : 5 to 18% by mass, Li 2 O: 1 to 10% by mass, Na 2 O: 3 to 15% by mass based on oxides.
  • K 2 O 0.1 to 5% by mass, provided that the total amount of Li 2 O + Na 2 O + K 2 O: 10 to 25% by mass, MgO: 0.1 to 5% by mass, CaO: 0.1 to 5% by mass ZrO 2 : 0 to 8% by mass (including 0), and the mass ratio of (MgO + CaO) to (Li 2 O + Na 2 O + K 2 O) is 0.10 ⁇ (MgO + CaO) / (Li 2 O + Na 2 O + K 2 A glass composition having a range of O) ⁇ 0.80 is used.
  • the disk processing step is a step of processing a glass base plate formed into a plate shape from the glass material into a disk-shaped glass base plate having through holes 10b (shown in FIG. 5B).
  • a disk-shaped glass base plate having an outer diameter of 2.5 inches, 1.8 inches, 1 inch, 0.8 inches, etc. and a thickness of 2 mm, 1 mm, 0.63 mm, etc. is formed. Is done.
  • size and thickness of the glass base plate formed by a disk processing process are not specifically limited.
  • the lapping step is a step of processing the glass base plate into a predetermined plate thickness.
  • the lapping process is composed of two processes, a first lapping process and a second lapping process.
  • both the front and back surfaces of the glass base plate are lapped to preliminarily adjust the overall shape of the glass base plate, that is, the parallelism, flatness and thickness of the glass base plate.
  • both the front and back surfaces of the glass base plate are again lapped to finely adjust the parallelism, flatness and thickness of the glass base plate.
  • a grinding apparatus 1 for lapping both front and back surfaces of the glass base plate in the first and second lapping processes uses an apparatus capable of simultaneous grinding on both sides as shown in FIG.
  • the grinding apparatus 1 includes an apparatus main body 1a and a grinding liquid supply unit 1b that supplies a grinding liquid to the apparatus main body 1a.
  • the apparatus main body 1a includes a disk-shaped upper surface plate 2 and a lower surface plate 3 that are spaced apart from each other so as to be parallel to each other, and rotate in opposite directions.
  • the diamond sheets 4 as a plurality of grinding members for lapping both the front and back surfaces of the glass base plate 10 are attached to the opposing surfaces of the upper and lower surface plates 2 and 3.
  • a plurality of rotatable carriers 41 are provided between the upper and lower surface plates 2 and 3.
  • the carrier 41 is provided with a plurality of base plate holding holes 42, and the glass base plate 10 is fitted and disposed in the base plate holding holes 42.
  • the carrier 41 is configured such that 100 glass base plates 10 can be fitted and arranged, and 100 glass base plates 10 can be lapped by one processing (one batch). It has become. Further, the upper and lower surface plates 2 and 3 can be operated by separate driving.
  • the carrier 41 sandwiched between the surface plates 2 and 3 via the diamond sheet 4 holds the plurality of glass base plates 10 and rotates with the lower surface plate 3 with respect to the rotation center of the surface plates 2 and 3 while rotating. Revolve in the same direction.
  • the glass 7 is supplied by supplying the grinding liquid 7 between the upper surface plate 2 and the glass base plate 10 and between the lower surface plate 3 and the glass base plate 10. The lapping of the base plate 10 can be performed.
  • the diamond sheet 4 having a particle size of about 9 ⁇ m is used in the first lapping step, and a particle size of about 4 ⁇ m is used in the second lapping step.
  • the grinding liquid supply unit 1 b includes a liquid storage unit 11 and a liquid recovery unit 12.
  • the liquid reservoir 11 includes a liquid reservoir main body 11a and a liquid supply pipe 11b having a discharge port 11e extending from the liquid reservoir main body 11a to the apparatus main body 1a.
  • the liquid recovery part 12 was extended from the liquid recovery part main body 12a, the liquid recovery pipe 12b extended from the liquid recovery part main body 12a to the apparatus main body part 1a, and the grinding liquid supply part 1b from the liquid recovery part main body 12a. And a liquid return pipe 12c.
  • the grinding fluid 7 put into the liquid storage part main body 11a is supplied to the apparatus main body part 1a from the discharge port 11e of the liquid supply pipe
  • the recovered grinding fluid 7 is returned to the liquid storage part 11 through the liquid return pipe 12c, and can be supplied again to the apparatus main body 1a. Therefore, the liquid circulation path 6 of the grinding liquid supply part 1b is formed by the liquid storage part main body 11a, the liquid supply pipe 11b, the liquid recovery pipe 12b, the liquid recovery part main body 12a, and the liquid return pipe 12c.
  • the grinding fluid supply unit 1 b includes a metal ion removal filter 8 in the middle of the fluid circulation path 6.
  • the grinding liquid 7 passes through the metal ion removal filter 8 when circulating through the liquid circulation path 6, and metal ions contained in the grinding liquid, such as calcium ions, magnesium ions, and further cerium ions, are transmitted into the metal ions during the permeation. It is removed by the removal filter 8.
  • the metal ion removal filter 8 is provided in the liquid recovery part main body 12a, and metal ions are removed when the liquid recovery part main body 12a is returned to the liquid storage part main body 11a. .
  • the grinding fluid 7 is in a novel state that has not yet been used for lapping, for example, polyalkylene glycol, alkylene glycol monoalkyl ether, alcohol (methanol, etc.), fatty acid, nonion, amines (monoethanol). Those containing amine, diethanolamine, triethanolamine, etc.).
  • the grinding fluid 7 is used while the total content of calcium and magnesium eluted from the glass base plate during lapping is always maintained at 5 mg / L or less. If the total content of calcium and magnesium is 5 mg / L or less, clogging of the diamond sheet 4 as a grinding member is difficult to occur, and if it exceeds 5 mg / L, clogging of the diamond sheet 4 is likely to occur. is there.
  • the diamond sheet 4 can be further prevented from being clogged by using the calcium and magnesium so that the total amount is always 3 mg / L or less.
  • the grinding liquid 7 is used while maintaining a state where the cerium content is always 10 mg / L or less. Cerium is also eluted from the glass base plate into the grinding liquid 7 during lapping, but if the cerium content is 10 mg / L or less, clogging of the diamond sheet 4 as a grinding member can hardly occur, and if it exceeds 10 mg / L. This is because the diamond sheet 4 is easily clogged.
  • the lapping process starts from a state where the amount of calcium and magnesium in the grinding fluid 7 is very small. Can start. Further, the lapping process can be started from a state where the amount of cerium in the grinding liquid 7 is very small.
  • the surface roughness of the glass substrate is about 2 to 4 ⁇ m for Rmax and about 0.2 to 0.4 ⁇ m for Ra. Is preferable.
  • the outer peripheral TIR of the glass base plate (as described above, the TIR in the circumferential direction at a position satisfying 0.75 ⁇ r1 [the radius of the glass base plate] from the center of the glass base plate).
  • the outer circumference TIR of the glass substrate for information recording medium 10a obtained by precision polishing is 0.7 ⁇ m or less and the inner circumference TIR is 0.2 ⁇ m or less, the information recording manufactured from the glass substrate for information recording medium 10a
  • the head of the disk device can be lowered and the high-speed rotation can be easily handled, and recording and reproduction can be performed stably.
  • the contact between the head and the information recording medium Can reduce the risk of recording / playback errors.
  • the outer peripheral TIR of the glass base plate exceeds 1.4 ⁇ m at the time when the second lapping process is completed
  • the outer peripheral TIR of the glass substrate 10a for information recording medium obtained by precision polishing after the second lapping process is
  • the inner circumference TIR of the information recording medium glass substrate 10a obtained by precision polishing after the second lapping step is 0.2 ⁇ m or less. It is hard to become. Therefore, as described above, when the second lapping step is finished, the outer peripheral TIR of the glass base plate is set to 1.4 ⁇ m or less and the inner peripheral TIR is set to 0.7 ⁇ m or less.
  • a cleaning step for removing the abrasive and glass powder remaining on the surface of the glass base plate.
  • the rough polishing step improves the surface roughness so that the surface roughness finally required in the precision polishing step described later can be efficiently obtained.
  • the precision polishing step described later is a step of polishing the surface of the glass base plate after the rough polishing step more precisely.
  • the rough polishing method is, for example, a polishing apparatus having the same configuration as the grinding apparatus 1 used in the first and second lapping processes except that a pad and a polishing liquid are used instead of the diamond sheet 4 and the polishing liquid used in the lapping process. Can be used.
  • the glass base plate is immersed in a chemical strengthening solution to form a chemical strengthening layer on the glass base plate.
  • a chemical strengthening solution to form a chemical strengthening layer on the glass base plate.
  • This chemical strengthening step involves immersing the glass base plate in a heated chemical strengthening treatment solution to convert alkali metal ions such as lithium ions and sodium ions contained in the glass base plate into alkali ions such as potassium ions having a larger ion radius. This is performed by an ion exchange method in which metal ions are substituted. Compressive stress is generated in the ion-exchanged region due to the strain caused by the difference in ion radius, and the surface of the glass base plate is strengthened.
  • the chemical strengthening process can be performed after the precision polishing process, or can be omitted and changed as appropriate.
  • the polishing apparatus 5 is used for the precision polishing process. In this embodiment, the operation is performed using what is generally called an Oscar polishing machine. As shown in FIGS. 4 to 6, the polishing apparatus 5 includes an upper polishing dish 51, a lower polishing dish 52, and a substrate holding member 53.
  • the upper polishing dish 51 is composed of a circular cross section, and has a polishing pad on the lower surface side.
  • the upper polishing plate 51 having the polishing pad configured as described above is configured to be movable in the horizontal direction (XX direction in the drawing).
  • the lower polishing dish 52 is provided with a storage recess 52a for storing the glass base plate 10 on the upper surface side thereof.
  • the storage recess 52 a is formed in a circular shape so as to be recessed at a predetermined depth, and its bottom surface is disposed horizontally so as to face the lower surface of the upper polishing dish 51.
  • a polishing pad is disposed on the bottom surface of the storage recess 52a. This polishing pad has the same configuration as the polishing pad of the upper polishing plate 51.
  • the lower polishing dish 52 is provided with a shaft portion 52b on the lower surface side thereof, and is configured to rotate around its axis when the shaft portion 52b is rotated.
  • the substrate holding member 53 has a cylindrical shape whose thickness is thinner than the thickness of the glass base plate 10 (in this embodiment, the inner diameter is 65 mm, the outer diameter is 67 mm, the thickness is 0. 5 mm), and the glass base plate 10 can be put in the hole 53a.
  • a plurality of glass base plates 10 placed in the holes 53a of the substrate holding member 53 are disposed so as to be placed in the storage recesses 52a of the lower polishing dish 52, as shown in FIG. 4 and FIG. 6B, the upper polishing dish 51 is disposed so as to cover the entire storage recess 52a from above.
  • the polishing apparatus 5 is configured such that 100 glass base plates 10 can be disposed in the storage recess 52a of the lower polishing plate 52, and 100 glass base plates are processed in one process (one batch). The plate 10 can be polished simultaneously.
  • the head of the disk device can be easily lowered and can cope with high-speed rotation. Therefore, the outer periphery TIR is 0.7 ⁇ m or less because the recording / reproduction can be performed stably and the risk of recording / reproduction errors due to the contact between the head and the information recording medium can be reduced.
  • the glass base plate 10 is preferably polished so that the inner circumference TIR is 0.2 ⁇ m or less.
  • the glass substrate 10a for information recording media shown in FIG. 1 can be formed.
  • the formed information recording medium glass substrate 10a is cleaned in the final cleaning step, and the deposits are removed.
  • the polishing apparatus used in the precision polishing step is not limited to the one that is performed using the polishing apparatus 5, and other polishing apparatuses, for example, the grinding apparatus 1 used in the lapping process, and the diamond sheet 4 as a polishing pad are used. It can also be used by exchanging them with each other, and can be changed as appropriate. Further, the first lapping step, the second lapping step, and the rough polishing step can also be performed using the polishing apparatus 5 by exchanging the polishing pad, but can also be performed using other polishing apparatuses. Can be changed as appropriate.
  • a lapping process was comprised from two, a 1st lapping process and a 2nd lapping process, for example, a lapping process can also be comprised from 1 or 3 or more processes, and is suitably Can be changed.
  • a method for producing a glass substrate for information recording medium is a method for producing a glass substrate for information recording medium, comprising a lapping step of lapping the surface of a glass base plate using a grinding apparatus and a grinding liquid, wherein the lapping step In the above grinding fluid, the total content of calcium and magnesium is always 5 mg / L or less, and the radius of the glass base plate is set to r1, at a position of 0.75 ⁇ r1 from the center of the glass base plate.
  • the outer periphery TIR is 1.4 ⁇ m or less
  • the radius of the glass base plate is r1
  • the radius of the through hole of the glass base plate is r2, from the center of the glass base plate (2 ⁇
  • the glass base plate is lapped so that an inner circumference TIR obtained by measuring a circumferential TIR for one track at a position of r2 + r1) / 3 is 0.7 ⁇ m or less.
  • the grinding liquid is set so that the total content of calcium and magnesium is always 5 mg / L or less, so that the outer periphery TIR is 1.4 ⁇ m or less and the inner periphery TIR is 0.7 ⁇ m or less. Since the lapping process is performed, the flatness of the glass substrate for an information recording medium obtained through a subsequent process such as a precision polishing process performed after the lapping process can be improved.
  • Another aspect is characterized in that, in the method for producing a glass substrate for an information recording medium, the grinding liquid is diluted with water having a total content of calcium and magnesium of 1 mg / L or less. To do.
  • the grinding fluid includes a step of diluting with water having a total content of calcium and magnesium of 1 mg / L or less, for example, the amount of calcium and magnesium in the grinding fluid is very small. Since the lapping process can be started from this, clogging of the grinding member can be suppressed, and a decrease in flatness can be suppressed.
  • Another aspect is characterized in that, in the above-described method for manufacturing a glass substrate for an information recording medium, the grinding apparatus is provided with a metal ion removal filter.
  • the components of calcium and magnesium contained in the glass base plate that is the object of the lapping process are included in the grinding liquid during the lapping process. Even if it comes out, the total content of calcium and magnesium in the grinding fluid can be maintained at 5 mg / L or less at all times.
  • Another aspect is that in the above-described method for producing a glass substrate for an information recording medium, the grinding liquid is lapped so that the total content of calcium and magnesium is always 3 mg / L or less.
  • This configuration can further prevent clogging of the grinding member.
  • Another aspect is characterized in that, in the above-described method for producing a glass substrate for an information recording medium, the grinding liquid is lapped so that the cerium content is always 10 mg / L or less.
  • the grinding member If the amount of cerium contained in the grinding fluid exceeds 10 mg / L, the grinding member will be clogged and scratches will occur on the grinding surface, or the flatness of the grinding surface will deteriorate. There is a high risk of accelerating deterioration. Therefore, if the cerium content is always 10 mg / L or less as described above, clogging of the grinding member can be suppressed. Thereby, generation
  • Another aspect includes a precision polishing step in which the surface of the glass base plate is polished using a polishing apparatus after the lapping step in the method for manufacturing a glass substrate for an information recording medium.
  • the glass base plate is polished so that the outer periphery TIR is 0.7 ⁇ m or less and the inner periphery TIR is 0.2 ⁇ m or less.
  • the information recording medium glass substrate obtained by polishing the glass base plate has an outer peripheral TIR of 0.7 ⁇ m or less and an inner peripheral TIR of 0.2 ⁇ m or less.
  • the inner circumference TIR to 0.2 ⁇ m or less, for example, even when an information recording medium manufactured from a glass substrate for information recording medium is mounted on a disk device by a clamp mechanism, distortion of the information recording medium caused by the clamp And the contact between the head and the information recording medium can be more reliably prevented.
  • the glass base plate is composed of SiO 2 : 55 to 75 mass%, Al 2 O 3 : 5 to 18 mass%, Li 2 O: 1 To 10% by mass, Na 2 O: 3 to 15% by mass, K 2 O: 0.1 to 5% by mass, provided that the total amount of Li 2 O + Na 2 O + K 2 O: 10 to 25% by mass, MgO: 0.1 To 5 mass%, CaO: 0.1 to 5 mass%, ZrO 2 : 0 to 8 mass% (including 0), and the mass ratio of (MgO + CaO) to (Li 2 O + Na 2 O + K 2 O) is 0 10 ⁇ (MgO + CaO) / (Li 2 O + Na 2 O + K 2 O) ⁇ 0.80 is used.
  • the glass base plate having a glass composition in the above range is used, so that the glass base plate has appropriate heat resistance, for example, even when chemical strengthening is performed, thermal deformation during the chemical strengthening process is suppressed. Can do.
  • the ion exchange is uniformly performed during the chemical strengthening step, and a uniform compressive stress can be applied to the surface of the glass base plate, and deterioration of the flatness of the glass base plate can be suppressed. Therefore, for example, when polishing is performed after the chemical strengthening step, it is possible to prevent the flatness from being deteriorated due to the balance of the chemical strengthening layer (compressive stress layer) being lost due to the polishing.
  • Example 1 A disk-shaped glass base plate having the following composition was produced.
  • the glass base plate used in Example 1 is SiO 2 : 64.5% by mass, Al 2 O 3 : 14.9% by mass, Li 2 O: 3.6% by mass, Na 2 O: 11.2% by mass.
  • CeO 2 0.5 mass%
  • ZrO 2 2.0 mass%
  • SnO 2 0. 7% by mass.
  • the manufactured disc-shaped glass base plate is ground by using the grinding apparatus 1 provided with the metal ion removing filter 8 and diluting the grinding liquid with water in which the total amount of calcium and magnesium is 1 mg / L or less.
  • the total amount of calcium and magnesium in the liquid was always 3 mg / L or less, and the amount of cerium was kept at 10 mg / L or less for grinding.
  • a diamond sheet 4 having a particle size of 9 ⁇ m was used, and in the second lapping step, a diamond sheet 4 having a particle size of 4 ⁇ m was used.
  • one 200-th batch glass substrate for information recording medium formed by polishing the glass base plate after the second lapping step in the precision polishing step (the 200th batch glass base plate after the completion of the second lapping step)
  • the same inner circumference TIR and outer circumference TIR were measured (FIG. 7, Example 1).
  • the inner circumference TIR and the outer circumference TIR of one glass substrate for an information recording medium in the 1000th batch (the same as the 1000th batch glass blank after the second lapping step) were measured (FIG. 7, implementation). Example 1).
  • Example 2 For the disk-shaped glass base plate having the same composition as in Example 1, the grinding fluid is diluted with water whose total amount of calcium and magnesium is 1 mg / L or less, and the total amount of calcium and magnesium in the grinding fluid is 3 mg / L to Grinding was performed so that the amount was 5 mg / L or less and the amount of cerium was 10 mg / L or less. The other conditions were the same as in Example 1.
  • Example 2 While measuring the inner circumference TIR and the outer circumference TIR of the glass base plates of the 200th batch and the 1000th batch after finishing the second lapping process, they were polished in the precision polishing process.
  • the inner circumference TIR and outer circumference TIR of the formed 200th and 1000th batch information recording medium glass substrates (the same as the 200th and 1000th batches after the second lapping step) were measured, respectively. (FIG. 7, Example 2).
  • Comparative Example 1 Further, as Comparative Example 1, for a disk-shaped glass base plate having the same composition as in Example 1, the grinding fluid was diluted with water having a total amount of calcium and magnesium of 1 mg / L or less, and calcium and magnesium in the grinding fluid were diluted. The total amount of was ground at 5 mg / L or less. The amount of cerium was not controlled.
  • Example 1 while measuring the inner circumference TIR and the outer circumference TIR of the glass base plates of the 200th batch and the 1000th batch after finishing the second lapping process, they were polished in the precision polishing process.
  • the inner circumference TIR and outer circumference TIR of the formed 200th and 1000th batch information recording medium glass substrates (the same as the 200th and 1000th batches after the second lapping step) were measured, respectively. (FIG. 7, Comparative Example 1).
  • Comparative Example 2 As Comparative Example 2, for the disk-shaped glass base plate having the same composition as in Example 1, after diluting the grinding liquid with tap water, the grinding liquid is allowed to pass through the metal ion removal filter so that calcium in the grinding liquid is obtained. And the total amount of magnesium was kept at 5 mg / L or less, and the amount of cerium was kept at 10 mg / L or less for grinding.
  • the diluted tap water has a total calcium and magnesium content of 15 mg / L
  • the grinding fluid used for processing immediately after dilution has a total calcium and magnesium content of 5 mg / L.
  • the total amount of calcium and magnesium in the grinding fluid is 5 mg / L or less and the amount of cerium is 10 mg / L or less.
  • the grinding fluid was used for processing in the state.
  • Example 2 While measuring the inner circumference TIR and the outer circumference TIR of the glass base plates of the 200th batch and the 1000th batch after finishing the second lapping process, they were polished in the precision polishing process.
  • the inner circumference TIR and outer circumference TIR of the formed 200th and 1000th batch information recording medium glass substrates (the same as the 200th and 1000th batches after the second lapping step) were measured, respectively. (FIG. 7, comparative example 2).
  • Comparative Example 3 As Comparative Example 3, for the disk-shaped glass base plate having the same composition as in Example 1, the grinding fluid was diluted with water having a total amount of calcium and magnesium of 1 mg / L or less, and the amounts of calcium and magnesium were not controlled. The amount of cerium was kept at 10 mg / L or less for grinding.
  • the amount of calcium and magnesium was not controlled by using a metal ion removing filter that was made to remove only cerium by adjusting a chelating material so that calcium and magnesium could permeate.
  • the total amount of calcium and magnesium contained in the grinding fluid used for processing immediately after dilution was 5 mg / L or less. Thereafter, calcium and magnesium contained in the glass base plate were released into the grinding fluid. The content gradually increased to a total amount of 5 mg / L or more.
  • Example 1 while measuring the inner circumference TIR and the outer circumference TIR of the glass base plates of the 200th batch and the 1000th batch after finishing the second lapping process, they were polished in the precision polishing process.
  • the inner circumference TIR and outer circumference TIR of the formed 200th and 1000th batch information recording medium glass substrates were measured, respectively. (FIG. 7, comparative example 3).
  • Comparative Example 4 As Comparative Example 4, for a disk-shaped glass base plate having the same composition as in Example 1, the grinding liquid was diluted with tap water, and the amount of cerium was kept at 10 mg / L or less without controlling the amounts of calcium and magnesium. did.
  • the grinding fluid used for the processing immediately after dilution has a total content of calcium and magnesium of 5 mg / L or more, and then calcium and magnesium contained in the glass base plate come out into the grinding fluid. The content gradually increased. Also in this case, since the total content of calcium and magnesium is 5 mg / L or more, the calcium and magnesium produce metal salts with fatty acids or nonions contained in the grinding fluid to produce the first and second diamond sheets 4. It seems that it helped clogging.
  • Example 1 while measuring the inner circumference TIR and the outer circumference TIR of the glass base plates of the 200th batch and the 1000th batch after finishing the second lapping process, they were polished in the precision polishing process.
  • the inner circumference TIR and outer circumference TIR of the formed 200th and 1000th batch information recording medium glass substrates were measured, respectively. (FIG. 7, comparative example 4).
  • Comparative Example 5 As Comparative Example 5, a disk-shaped glass base plate having the same composition as in Example 1 was diluted with tap water and ground without controlling the amounts of calcium, magnesium, and cerium without using a metal ion removal filter. . Therefore, the grinding fluid used for processing immediately after dilution has a total content of calcium and magnesium of 5 mg / L or more, and thereafter, calcium, magnesium and cerium contained in the glass base plate appear in the grinding fluid. The content gradually increased.
  • Example 1 while measuring the inner circumference TIR and the outer circumference TIR of the glass base plates of the 200th batch and the 1000th batch after finishing the second lapping process, they were polished in the precision polishing process.
  • the inner circumference TIR and outer circumference TIR of the formed 200th and 1000th batch information recording medium glass substrates were measured, respectively. (FIG. 7, comparative example 5).
  • the inner peripheral TIR of the glass base plate after the second lapping process of the 1000th batch is 0.7 ⁇ m or less and the outer peripheral TIR is 1.4 ⁇ m or less.
  • the glass substrate for information recording medium had an inner circumference TIR of 0.2 ⁇ m or less and an outer circumference TIR of 0.7 ⁇ m or less.
  • the inner circumference TIR of the glass base plate after the second lapping process of the 1000th batch does not become 0.7 ⁇ m or less, and the inner circumference TIR of the glass substrate for information recording medium after the precision polishing process. was not less than 0.2 ⁇ m.
  • the inner circumference TIR of the glass base plate after the second lapping process of the 200th batch does not become 0.7 ⁇ m or less, and the inner circumference TIR of the glass substrate for information recording medium after the precision polishing process is 0. It was not less than 2 ⁇ m.
  • the present invention has wide industrial applicability in the technical field of the method for producing a glass substrate for information recording media.

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Abstract

Provided is a method for manufacturing a glass substrate for information recording media, said method comprising a lapping process in which a grinding fluid has total included amounts of calcium and magnesium that are usually no more than 5 mg/L, and a rough glass plate is subjected to lapping in such a way that the outer circumferential TIR becomes 1.4 μm or less and the inner circumferential TIR becomes 0.7 μm or less. In this method for manufacturing a glass substrate for information recording media there is little risk of a grinding member becoming clogged and the TIR of a rough glass plate after the lapping process is equal to or less than a constant value, and it is therefore possible to obtain a glass substrate for information recording media having a good TIR.

Description

情報記録媒体用ガラス基板の製造方法Manufacturing method of glass substrate for information recording medium
　本発明は、情報記録媒体用ガラス基板の製造方法に関する。 The present invention relates to a method for producing a glass substrate for an information recording medium.
　情報記録媒体に記録される情報の高密度化に伴い、情報記録媒体用ガラス基板に求められる要求は上がっており、平滑化、高清浄化が必須となっている。情報記録媒体用ガラス基板は、一般に、ラッピング（研削）工程や研磨工程等を経て製造される。従来、ラッピング工程では、純水を溶媒とした研削液を使用することにより、或いは研磨屑などの研磨スラッジ成分を分離する機能を備えた研削装置を使用することにより、研削装置に設けられた研削部材としての砥石の目詰まりを防止するようにしている（特許文献１参照）。 With the increase in the density of information recorded on information recording media, demands for glass substrates for information recording media are increasing, and smoothing and high cleaning are essential. The glass substrate for information recording media is generally manufactured through a lapping (grinding) process or a polishing process. Conventionally, in the lapping process, grinding provided in the grinding apparatus by using a grinding liquid using pure water as a solvent or by using a grinding apparatus having a function of separating polishing sludge components such as polishing scraps. Clogging of the grindstone as a member is prevented (see Patent Document 1).
　しかしながら、上記のような研削液を使用しても、砥石やダイヤモンドシート等の研削部材に目詰まりを起こすおそれがある。又、このような場合に、上述のスラッジ分離機能を備えた研削装置を使用したとしても、目詰まりを防止するのは難しい。 However, even if the above grinding fluid is used, there is a risk of clogging the grinding member such as a grindstone or a diamond sheet. In such a case, it is difficult to prevent clogging even if a grinding apparatus having the above-described sludge separation function is used.
特開２００２－２４１７４２号公報JP 2002-241742 A
　本発明は、研削部材が目詰まりを起こすおそれが少なく、ラッピング工程後のガラス素板のＴＩＲを一定値以下にしてＴＩＲの良好な情報記録媒体用ガラス基板を得ることができる情報記録媒体用ガラス基板の製造方法の提供を目的とする。 INDUSTRIAL APPLICABILITY The present invention provides a glass for an information recording medium that is less likely to cause clogging of a grinding member and that can provide a glass substrate for an information recording medium having a good TIR by setting the TIR of the glass base plate after the lapping step to a certain value or less It aims at providing the manufacturing method of a board | substrate.
　本発明の一局面は、ガラス素板の表面を、研削装置と研削液とを用いてラッピング加工するラッピング工程を含む情報記録媒体用ガラス基板の製造方法であって、上記ラッピング工程で、上記研削液を、カルシウムとマグネシウムとの含有量が総量で常時５ｍｇ／Ｌ以下にして、ガラス素板の半径をｒ１としたときにガラス素板の中心から０．７５×ｒ１の位置で周方向のＴＩＲをトラック１周分測定した外周ＴＩＲが１．４μｍ以下、ガラス素板の半径をｒ１としガラス素板の貫通穴の半径をｒ２としたときにガラス素板の中心から（２×ｒ２＋ｒ１）／３の位置で周方向のＴＩＲをトラック１周分測定した内周ＴＩＲが０．７μｍ以下になるように、上記ガラス素板をラッピング加工することを特徴とする。 One aspect of the present invention is a method for manufacturing a glass substrate for an information recording medium, which includes a lapping process in which a surface of a glass base plate is lapped using a grinding apparatus and a grinding liquid, and the grinding is performed in the lapping process. When the total content of calcium and magnesium is always 5 mg / L or less and the radius of the glass base plate is r1, the TIR in the circumferential direction is 0.75 × r1 from the center of the glass base plate. (2 × r2 + r1) / 3 from the center of the glass base plate when the outer periphery TIR measured for one track is 1.4 μm or less, the radius of the glass base plate is r1, and the radius of the through hole of the glass base plate is r2. The glass base plate is lapped so that the inner circumference TIR obtained by measuring the TIR in the circumferential direction at a position of 1 at a position of 0.7 μm or less.
　上記並びにその他の本発明の目的、特徴、局面及び利点は、以下の詳細な記載と添付図面とから明らかになるであろう。 The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.
本発明の製造方法により製造した一実施形態の情報記録媒体用ガラス基板の斜視図である。It is a perspective view of the glass substrate for information recording media of one Embodiment manufactured with the manufacturing method of this invention. 本発明の情報記録媒体用ガラス基板の製造方法の一実施形態の工程図である。It is process drawing of one Embodiment of the manufacturing method of the glass substrate for information recording media of this invention. ラッピング工程に用いる研削装置の説明図である。It is explanatory drawing of the grinding device used for a lapping process. 精密研磨工程における研磨装置でガラス素板を研磨している状態の正面図である。It is a front view of the state which has grind | polished a glass base plate with the grinding | polishing apparatus in a precision grinding | polishing process. （ａ）は、研磨装置の下研磨皿に、ガラス素板を配設した状態の平面図、（ｂ）は、基板保持部材にガラス素板を入れて保持させた状態の拡大平面図である。(A) is a top view of the state which has arrange | positioned the glass base plate in the lower grinding | polishing dish of a grinding | polishing apparatus, (b) is an enlarged plan view of the state which put and hold | maintained the glass base plate in the board | substrate holding member. . （ａ）は、上研磨皿が左側に移動した際の研磨装置の平面図、（ｂ）は、上研磨皿が下研磨皿の上にきて重なった際の研磨装置の平面図、（ｃ）は、上研磨皿が右側に移動した際の研磨装置の平面図である。(A) is a plan view of the polishing apparatus when the upper polishing dish is moved to the left side, (b) is a plan view of the polishing apparatus when the upper polishing dish is overlaid on the lower polishing dish, (c) ) Is a plan view of the polishing apparatus when the upper polishing dish moves to the right side. 実施例及び比較例について、第２ラッピング工程後と精密研磨工程後との夫々の内周ＴＩＲ及び外周ＴＩＲの測定値を表した図表である。It is a chart showing the measured values of the inner circumference TIR and the outer circumference TIR after the second lapping process and after the precision polishing process, for Examples and Comparative Examples. 内周ＴＩＲ及び外周ＴＩＲを説明する際の説明図である。It is explanatory drawing at the time of explaining inner periphery TIR and outer periphery TIR.
　ラッピング工程において、研削液中にカルシウムやマグネシウムが含まれていると、カルシウムやマグネシウムと研削液中の界面活性剤とで不溶性の金属塩を生成し、砥石やダイヤモンドシート等の研削部材に目詰まりを起こすおそれがある。又、カルシウムやマグネシウムを含有しないか又は含有量の少ない研削液を用いたとしても、ガラス素板の素材としてカルシウムやマグネシウムが含まれたものを使用すると、ラッピングに際して研削液中にカルシウム成分やマグネシウム成分が出て、カルシウム成分やマグネシウム成分と研削液中の界面活性剤とで不溶性の金属塩を生成し、その結果、上記のように研削部材に目詰まりを起こすおそれがある。又、このような場合に、従来のスラッジ分離機能を備えた研削装置を使用したとしても、生成したスラッジを分離するだけで、研削部材の目詰まりを防止するのは難しい。 In the lapping process, if the grinding fluid contains calcium or magnesium, an insoluble metal salt is formed by the calcium or magnesium and the surfactant in the grinding fluid, and clogging of grinding members such as grindstones and diamond sheets. There is a risk of causing. Even if a grinding fluid containing no or little calcium or magnesium is used, if a material containing calcium or magnesium is used as the material for the glass base plate, the calcium component or magnesium is contained in the grinding fluid during lapping. The component comes out, and an insoluble metal salt is generated by the calcium component or the magnesium component and the surfactant in the grinding fluid, and as a result, the grinding member may be clogged as described above. In such a case, even if a conventional grinding device having a sludge separation function is used, it is difficult to prevent clogging of the grinding member only by separating the generated sludge.
　このような目詰まりは、研削部材の全面に均一に起こるのではなく局所的に起こるため、ガラス素板の研削面のＴＩＲ（平坦度）が低下してしまう。ラッピング工程でのガラス素板の研削面のＴＩＲが低下した場合には、後の研磨工程で研磨して情報記録媒体用ガラス基板に仕上げた後のＴＩＲも良好なものになり難いという問題点がある。本発明はこのような検討の結果完成された。 Such clogging does not occur uniformly on the entire surface of the grinding member but occurs locally, so that the TIR (flatness) of the ground surface of the glass base plate is lowered. When the TIR of the ground surface of the glass base plate in the lapping process is lowered, the TIR after polishing in the subsequent polishing process to finish the glass substrate for an information recording medium is difficult to improve. is there. The present invention has been completed as a result of such studies.
　ここに、ＴＩＲは、情報記録媒体用ガラス基板又はガラス素板の平坦度（うねり量）を表す指標をいい、評価面（基板表面）の最小二乗平面からの最高点と最低点との距離の合計である。本実施形態では、外周ＴＩＲは、図８に示すように、情報記録媒体用ガラス基板１０ａ又はガラス素板１０の半径をｒ１としたときに、ガラス基板１０ａ又はガラス素板１０の中心から０．７５×ｒ１を満たす位置で周方向のＴＩＲをトラック１周分測定したものである。本実施形態では、内周ＴＩＲは、情報記録媒体用ガラス基板１０ａ又はガラス素板１０の半径をｒ１、貫通穴１０ｂの半径をｒ２としたときに、ガラス基板１０ａ又はガラス素板１０の中心から（２×ｒ２＋ｒ１）／３を満たす位置で周方向のＴＩＲをトラック１周分測定したものである。 Here, TIR refers to an index representing the flatness (waviness) of the glass substrate or glass base plate for an information recording medium, and is the distance between the highest point and the lowest point from the least square plane of the evaluation surface (substrate surface). Total. In the present embodiment, as shown in FIG. 8, the outer periphery TIR is 0. 0 from the center of the glass substrate 10 a or the glass base plate 10 when the radius of the glass substrate 10 a for information recording medium or the glass base plate 10 is r1. The TIR in the circumferential direction is measured for one track at a position satisfying 75 × r1. In this embodiment, the inner circumference TIR is from the center of the glass substrate 10a or the glass base plate 10 when the radius of the information recording medium glass substrate 10a or the glass base plate 10 is r1 and the radius of the through hole 10b is r2. The TIR in the circumferential direction was measured for one track at a position satisfying (2 × r2 + r1) / 3.
　以下、本発明の実施形態を説明する。ただし、本発明はこの実施形態に限定されない。図１は、本発明の製造方法により製造した一実施形態の情報記録媒体用ガラス基板の斜視図、図２は、本発明の製造方法の一実施形態の工程図である。 Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to this embodiment. FIG. 1 is a perspective view of a glass substrate for an information recording medium of one embodiment manufactured by the manufacturing method of the present invention, and FIG. 2 is a process diagram of one embodiment of the manufacturing method of the present invention.
　この実施形態では、情報記録媒体用ガラス基板の製造方法は、円盤加工工程と、ラッピング工程と、粗研磨工程と、化学強化工程と、精密（最終）研磨工程と、最終洗浄工程とを含み、これらの工程を経て情報記録媒体用ガラス基板１０ａが製造される。 In this embodiment, the method of manufacturing the glass substrate for information recording medium includes a disk processing step, a lapping step, a rough polishing step, a chemical strengthening step, a precision (final) polishing step, and a final cleaning step. The glass substrate 10a for information recording media is manufactured through these steps.
　使用するガラス素材は、酸化物基準で、ＳｉＯ２：５５～７５質量％、Ａｌ２Ｏ３：５～１８質量％、Ｌｉ２Ｏ：１～１０質量％、Ｎａ２Ｏ：３～１５質量％、Ｋ２Ｏ：０．１～５質量％、但し、Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏの総量：１０～２５質量％、ＭｇＯ：０．１～５質量％、ＣａＯ：０．１～５質量％、ＺｒＯ２：０～８質量％（０を含む）であり、（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ）に対する（ＭｇＯ＋ＣａＯ）の質量比が、０．１０≦（ＭｇＯ＋ＣａＯ）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ）≦０．８０の範囲にあるガラス組成のものが用いられる。 The glass material to be used is SiO 2 : 55 to 75% by mass, Al 2 O 3 : 5 to 18% by mass, Li 2 O: 1 to 10% by mass, Na 2 O: 3 to 15% by mass based on oxides. K 2 O: 0.1 to 5% by mass, provided that the total amount of Li 2 O + Na 2 O + K 2 O: 10 to 25% by mass, MgO: 0.1 to 5% by mass, CaO: 0.1 to 5% by mass ZrO 2 : 0 to 8% by mass (including 0), and the mass ratio of (MgO + CaO) to (Li 2 O + Na 2 O + K 2 O) is 0.10 ≦ (MgO + CaO) / (Li 2 O + Na 2 O + K 2 A glass composition having a range of O) ≦ 0.80 is used.
　円盤加工工程は、上記ガラス素材から板状に形成したガラス素板を、貫通穴１０ｂを有する（図５（ｂ）に図示）円盤形状のガラス素板に加工する工程である。この円盤加工工程で、例えば、外径が２．５インチ、１．８インチ、１インチ、０．８インチ等で、厚みが２ｍｍ、１ｍｍ、０．６３ｍｍ等の円盤状のガラス素板が形成される。円盤加工工程で形成されるガラス素板の大きさや厚みは特に限定されない。 The disk processing step is a step of processing a glass base plate formed into a plate shape from the glass material into a disk-shaped glass base plate having through holes 10b (shown in FIG. 5B). In this disk processing step, for example, a disk-shaped glass base plate having an outer diameter of 2.5 inches, 1.8 inches, 1 inch, 0.8 inches, etc. and a thickness of 2 mm, 1 mm, 0.63 mm, etc. is formed. Is done. The magnitude | size and thickness of the glass base plate formed by a disk processing process are not specifically limited.
　ラッピング工程は、上記ガラス素板を所定の板厚に加工する工程である。この実施形態では、ラッピング工程は、第１ラッピング工程と、第２ラッピング工程との２つの工程から構成されている。 The lapping step is a step of processing the glass base plate into a predetermined plate thickness. In this embodiment, the lapping process is composed of two processes, a first lapping process and a second lapping process.
　第１ラッピング工程では、ガラス素板の表裏の両面をラッピング加工し、ガラス素板の全体形状、すなわちガラス素板の平行度、平坦度および厚みを予備調整する。 In the first lapping step, both the front and back surfaces of the glass base plate are lapped to preliminarily adjust the overall shape of the glass base plate, that is, the parallelism, flatness and thickness of the glass base plate.
　第２ラッピング工程では、更に、ガラス素板の表裏の両面を再びラッピング加工して、ガラス素板の平行度、平坦度および厚みを微調整する。 In the second lapping step, both the front and back surfaces of the glass base plate are again lapped to finely adjust the parallelism, flatness and thickness of the glass base plate.
　上記第１及び第２ラッピング工程においてガラス素板の表裏の両面をラッピング加工する研削装置１は、この実施形態では、例えば図３に示すような両面同時研削可能な装置を使用する。この研削装置１は、装置本体部１ａと、装置本体部１ａに研削液を供給する研削液供給部１ｂとを備えている。 In this embodiment, a grinding apparatus 1 for lapping both front and back surfaces of the glass base plate in the first and second lapping processes uses an apparatus capable of simultaneous grinding on both sides as shown in FIG. The grinding apparatus 1 includes an apparatus main body 1a and a grinding liquid supply unit 1b that supplies a grinding liquid to the apparatus main body 1a.
　装置本体部１ａは、互いに平行になるように上下に間隔を隔てて配置された円盤状の上定盤２と下定盤３とを備えており、互いに逆方向に回転する。 The apparatus main body 1a includes a disk-shaped upper surface plate 2 and a lower surface plate 3 that are spaced apart from each other so as to be parallel to each other, and rotate in opposite directions.
　この上下の定盤２、３の対向するそれぞれの面に、ガラス素板１０の表裏の両面をラッピング加工するための複数の研削部材としてのダイヤモンドシート４が貼り付けられている。上下の定盤２、３の間には、回転可能な複数のキャリア４１が設けられている。 The diamond sheets 4 as a plurality of grinding members for lapping both the front and back surfaces of the glass base plate 10 are attached to the opposing surfaces of the upper and lower surface plates 2 and 3. A plurality of rotatable carriers 41 are provided between the upper and lower surface plates 2 and 3.
　このキャリア４１には、複数の素板保持用孔４２が設けられており、この素板保持用孔４２にガラス素板１０をはめ込んで配置する。この実施形態では、キャリア４１は、１００枚のガラス素板１０をはめ込んで配置できるように構成されており、一回の処理（１バッチ）で１００枚のガラス素板１０をラッピング加工できるようになっている。又、上下の定盤２、３は別駆動で動作することができる。 The carrier 41 is provided with a plurality of base plate holding holes 42, and the glass base plate 10 is fitted and disposed in the base plate holding holes 42. In this embodiment, the carrier 41 is configured such that 100 glass base plates 10 can be fitted and arranged, and 100 glass base plates 10 can be lapped by one processing (one batch). It has become. Further, the upper and lower surface plates 2 and 3 can be operated by separate driving.
　ダイヤモンドシート４を介して定盤２、３に挟まれているキャリア４１は、複数のガラス素板１０を保持した状態で、自転しながら定盤２，３の回転中心に対して下定盤３と同じ方向に公転する。このような動作をしている研削装置１において、研削液７を上定盤２とガラス素板１０との間、及び下定盤３とガラス素板１０との間、夫々に供給することでガラス素板１０のラッピング加工を行うことができる。 The carrier 41 sandwiched between the surface plates 2 and 3 via the diamond sheet 4 holds the plurality of glass base plates 10 and rotates with the lower surface plate 3 with respect to the rotation center of the surface plates 2 and 3 while rotating. Revolve in the same direction. In the grinding apparatus 1 performing such an operation, the glass 7 is supplied by supplying the grinding liquid 7 between the upper surface plate 2 and the glass base plate 10 and between the lower surface plate 3 and the glass base plate 10. The lapping of the base plate 10 can be performed.
　ダイヤモンドシート４は、第１ラッピング工程では、粒度が９μｍ程度のものが使用され、第２ラッピング工程では、粒度が４μｍ程度のものが使用される。 The diamond sheet 4 having a particle size of about 9 μm is used in the first lapping step, and a particle size of about 4 μm is used in the second lapping step.
　研削液供給部１ｂは、液貯留部１１と液回収部１２とを備えている。液貯留部１１は、液貯留部本体１１ａと、液貯留部本体１１ａから装置本体部１ａに延ばされた吐出口１１ｅを有する液供給管１１ｂとを備えている。 The grinding liquid supply unit 1 b includes a liquid storage unit 11 and a liquid recovery unit 12. The liquid reservoir 11 includes a liquid reservoir main body 11a and a liquid supply pipe 11b having a discharge port 11e extending from the liquid reservoir main body 11a to the apparatus main body 1a.
　液回収部１２は、液回収部本体１２ａと、液回収部本体１２ａから装置本体部１ａに延ばされた液回収管１２ｂと、液回収部本体１２ａから研削液供給部１ｂに延ばされた液戻し管１２ｃとを備えている。 The liquid recovery part 12 was extended from the liquid recovery part main body 12a, the liquid recovery pipe 12b extended from the liquid recovery part main body 12a to the apparatus main body part 1a, and the grinding liquid supply part 1b from the liquid recovery part main body 12a. And a liquid return pipe 12c.
　そして、液貯留部本体１１ａに入れられた研削液７は、液供給管１１ｂの吐出口１１ｅから装置本体部１ａに供給され、装置本体部１ａから液回収管１２ｂを介して液回収部本体１２ａに回収される。 And the grinding fluid 7 put into the liquid storage part main body 11a is supplied to the apparatus main body part 1a from the discharge port 11e of the liquid supply pipe | tube 11b, and the liquid recovery part main body 12a is passed from the apparatus main body part 1a through the liquid recovery pipe | tube 12b. To be recovered.
　又、回収された研削液７は、液戻し管１２ｃを介して液貯留部１１に戻され、再度、装置本体部１ａに供給可能とされている。従って、液貯留部本体１１ａと液供給管１１ｂと液回収管１２ｂと液回収部本体１２ａと液戻し管１２ｃとによって、研削液供給部１ｂの液循環路６が形成されている。 Further, the recovered grinding fluid 7 is returned to the liquid storage part 11 through the liquid return pipe 12c, and can be supplied again to the apparatus main body 1a. Therefore, the liquid circulation path 6 of the grinding liquid supply part 1b is formed by the liquid storage part main body 11a, the liquid supply pipe 11b, the liquid recovery pipe 12b, the liquid recovery part main body 12a, and the liquid return pipe 12c.
　又、この実施形態では、研削液供給部１ｂは、その液循環路６の途中に、金属イオン除去フィルタ８を備えている。そして、研削液７が、液循環路６を循環するに際して金属イオン除去フィルタ８を透過し、その透過に際して研削液に含まれる金属イオン、例えばカルシウムイオン、マグネシウムイオン、さらにはセリウムイオン等が金属イオン除去フィルタ８によって除去されるようになっている。 In this embodiment, the grinding fluid supply unit 1 b includes a metal ion removal filter 8 in the middle of the fluid circulation path 6. The grinding liquid 7 passes through the metal ion removal filter 8 when circulating through the liquid circulation path 6, and metal ions contained in the grinding liquid, such as calcium ions, magnesium ions, and further cerium ions, are transmitted into the metal ions during the permeation. It is removed by the removal filter 8.
　この実施形態は、金属イオン除去フィルタ８は、液回収部本体１２ａに設けられており、液回収部本体１２ａから液貯留部本体１１ａに戻される際に金属イオンが除去されるようになっている。 In this embodiment, the metal ion removal filter 8 is provided in the liquid recovery part main body 12a, and metal ions are removed when the liquid recovery part main body 12a is returned to the liquid storage part main body 11a. .
　又、研削液７は、この実施形態では、ラッピング加工に未だ供していない新規な状態で、例えばポリアルキレングリコール、アルキレングリコールモノアルキルエーテル、アルコール（メタノールなど）、脂肪酸、ノニオン、アミン類（モノエタノールアミン、ジエタノールアミン、トリエタノールアミンなど）を含むものが使用される。 In this embodiment, the grinding fluid 7 is in a novel state that has not yet been used for lapping, for example, polyalkylene glycol, alkylene glycol monoalkyl ether, alcohol (methanol, etc.), fatty acid, nonion, amines (monoethanol). Those containing amine, diethanolamine, triethanolamine, etc.).
　又、研削液７は、ラッピング加工に際してガラス素板から溶出したカルシウムとマグネシウムとの含有量が総量で常時５ｍｇ／Ｌ以下の状態を維持しながら使用される。カルシウムとマグネシウムとの含有量が総量で５ｍｇ／Ｌ以下では、研削部材としてのダイヤモンドシート４に目詰まりを起こし難くでき、５ｍｇ／Ｌを越えると、ダイヤモンドシート４に目詰まりを起こし易くなるからである。 Moreover, the grinding fluid 7 is used while the total content of calcium and magnesium eluted from the glass base plate during lapping is always maintained at 5 mg / L or less. If the total content of calcium and magnesium is 5 mg / L or less, clogging of the diamond sheet 4 as a grinding member is difficult to occur, and if it exceeds 5 mg / L, clogging of the diamond sheet 4 is likely to occur. is there.
　より好ましくは、カルシウムとマグネシウムとの含有量が総量で常時３ｍｇ／Ｌ以下になるようにして使用することで、より一層、ダイヤモンドシート４の目詰まりを起こし難くできる。 More preferably, the diamond sheet 4 can be further prevented from being clogged by using the calcium and magnesium so that the total amount is always 3 mg / L or less.
　又、研削液７は、セリウムの含有量が常時１０ｍｇ／Ｌ以下の状態を維持しながら使用されるのが好ましい。セリウムも、ラッピング加工に際してガラス素板から研削液７に溶出するが、セリウムの含有量が１０ｍｇ／Ｌ以下では、研削部材としてのダイヤモンドシート４の目詰まりを起こし難くでき、１０ｍｇ／Ｌを越えると、ダイヤモンドシート４の目詰まりを起こし易くなるからである。 Moreover, it is preferable that the grinding liquid 7 is used while maintaining a state where the cerium content is always 10 mg / L or less. Cerium is also eluted from the glass base plate into the grinding liquid 7 during lapping, but if the cerium content is 10 mg / L or less, clogging of the diamond sheet 4 as a grinding member can hardly occur, and if it exceeds 10 mg / L. This is because the diamond sheet 4 is easily clogged.
　例えば、カルシウムとマグネシウムとの含有量が総量で１ｍｇ／Ｌ以下の水で希釈した研削液７を用いてラッピング加工をすると、研削液７中のカルシウムとマグネシウムの量が非常に少ない状態からラッピング工程を開始できる。また、研削液７中のセリウムの量が非常に少ない状態からラッピング工程を開始できる。 For example, when lapping is performed using the grinding fluid 7 diluted with water having a total content of calcium and magnesium of 1 mg / L or less, the lapping process starts from a state where the amount of calcium and magnesium in the grinding fluid 7 is very small. Can start. Further, the lapping process can be started from a state where the amount of cerium in the grinding liquid 7 is very small.
　第２ラッピング工程を終えた時点で、大きなうねり、欠け、ひび等の欠陥は除去され、ガラス素板の表面の面粗さは、Ｒｍａｘが２μｍから４μｍ、Ｒａが０．２μｍから０．４μｍ程度とするのが好ましい。又、第２ラッピング工程を終えた時点で、ガラス素板の外周ＴＩＲ（前述したように、ガラス素板の中心から０．７５×ｒ１［ガラス素板の半径］を満たす位置で周方向のＴＩＲをトラック１周分測定した値）が１．４μｍ以下、内周ＴＩＲ（前述したように、ガラス素板の中心から（２×ｒ２［貫通穴の半径］＋ｒ１［ガラス素板の半径］）／３を満たす位置で周方向のＴＩＲをトラック１周分測定した値）が０．７μｍ以下になるようにしておく。 Upon completion of the second lapping step, defects such as large undulations, chips and cracks are removed, and the surface roughness of the glass substrate is about 2 to 4 μm for Rmax and about 0.2 to 0.4 μm for Ra. Is preferable. When the second lapping step is completed, the outer peripheral TIR of the glass base plate (as described above, the TIR in the circumferential direction at a position satisfying 0.75 × r1 [the radius of the glass base plate] from the center of the glass base plate). Is a value measured for one track), and the inner circumference TIR (as described above, from the center of the glass base plate (2 × r2 [radius of the through hole] + r1 [radius of the glass base plate]) / 3) (a value obtained by measuring the TIR in the circumferential direction for one track at a position satisfying 3) is set to 0.7 μm or less.
　精密研磨をして得られる情報記録媒体用ガラス基板１０ａの外周ＴＩＲが０．７μｍ以下で、内周ＴＩＲが０．２μｍ以下の場合には、情報記録媒体用ガラス基板１０ａから製造された情報記録媒体をディスク装置に装着した場合において、ディスク装置のヘッドの低浮上化、高速回転への対応が容易になり、安定して記録・再生を行なうことができ、ヘッドと情報記録媒体との接触による記録・再生のエラーの危険性の少ないものにできる。 When the outer circumference TIR of the glass substrate for information recording medium 10a obtained by precision polishing is 0.7 μm or less and the inner circumference TIR is 0.2 μm or less, the information recording manufactured from the glass substrate for information recording medium 10a When the medium is mounted on the disk device, the head of the disk device can be lowered and the high-speed rotation can be easily handled, and recording and reproduction can be performed stably. By the contact between the head and the information recording medium Can reduce the risk of recording / playback errors.
　しかし、第２ラッピング工程を終えた時点で、ガラス素板の外周ＴＩＲが１．４μｍを越えると、第２ラッピング工程後の精密研磨をして得られる情報記録媒体用ガラス基板１０ａの外周ＴＩＲが０．７μｍ以下になり難く、又、内周ＴＩＲが０．７μｍを越えると、第２ラッピング工程後の精密研磨をして得られる情報記録媒体用ガラス基板１０ａの内周ＴＩＲが０．２μｍ以下になり難い。そのため、上述のように、第２ラッピング工程を終えた時点で、ガラス素板の外周ＴＩＲが１．４μｍ以下、内周ＴＩＲが０．７μｍ以下になるようにしておく。 However, when the outer peripheral TIR of the glass base plate exceeds 1.4 μm at the time when the second lapping process is completed, the outer peripheral TIR of the glass substrate 10a for information recording medium obtained by precision polishing after the second lapping process is When the inner circumference TIR exceeds 0.7 μm, the inner circumference TIR of the information recording medium glass substrate 10a obtained by precision polishing after the second lapping step is 0.2 μm or less. It is hard to become. Therefore, as described above, when the second lapping step is finished, the outer peripheral TIR of the glass base plate is set to 1.4 μm or less and the inner peripheral TIR is set to 0.7 μm or less.
　第１及び第２ラッピング工程の後、ガラス素板の表面に残った研磨剤やガラス粉を除去するための洗浄工程を行うことが好ましい。 After the first and second lapping steps, it is preferable to perform a cleaning step for removing the abrasive and glass powder remaining on the surface of the glass base plate.
　粗研磨工程は、後述の精密研磨工程で最終的に必要とされる面粗さを効率よく得ることができるように、面粗さを向上させる。尚、後述の精密研磨工程は、粗研磨工程後のガラス素板の表面を更に精密に研磨する工程である。 The rough polishing step improves the surface roughness so that the surface roughness finally required in the precision polishing step described later can be efficiently obtained. The precision polishing step described later is a step of polishing the surface of the glass base plate after the rough polishing step more precisely.
　粗研磨の方法は、例えばラッピング工程で使用したダイヤモンドシート４と研削液に代えて、パッドと研磨液を使用する以外は第１及び２ラッピング工程で使用した研削装置１と同一の構成の研磨装置を用いて行なうことができる。 The rough polishing method is, for example, a polishing apparatus having the same configuration as the grinding apparatus 1 used in the first and second lapping processes except that a pad and a polishing liquid are used instead of the diamond sheet 4 and the polishing liquid used in the lapping process. Can be used.
　化学強化工程は、化学強化液にガラス素板を浸漬してガラス素板に化学強化層を形成する。化学強化層を形成することで耐衝撃性、耐振動性及び耐熱性等を向上させることができる。 In the chemical strengthening step, the glass base plate is immersed in a chemical strengthening solution to form a chemical strengthening layer on the glass base plate. By forming the chemical strengthening layer, impact resistance, vibration resistance, heat resistance and the like can be improved.
　この化学強化工程は、加熱された化学強化処理液にガラス素板を浸漬することによってガラス素板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をそれより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するイオン交換法によって行われる。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、ガラス素板の表面が強化される。 This chemical strengthening step involves immersing the glass base plate in a heated chemical strengthening treatment solution to convert alkali metal ions such as lithium ions and sodium ions contained in the glass base plate into alkali ions such as potassium ions having a larger ion radius. This is performed by an ion exchange method in which metal ions are substituted. Compressive stress is generated in the ion-exchanged region due to the strain caused by the difference in ion radius, and the surface of the glass base plate is strengthened.
　化学強化工程は、精密研磨工程の後に実施し、或いは、省略することもでき、適宜変更できる。 The chemical strengthening process can be performed after the precision polishing process, or can be omitted and changed as appropriate.
　精密研磨工程は、研磨装置５が使用される。この実施形態では、オスカー研磨機と一般に言われているものを用いて行なわれている。この研磨装置５は、図４～図６に示すように、上研磨皿５１と、下研磨皿５２と、基板保持部材５３とを備えている。 The polishing apparatus 5 is used for the precision polishing process. In this embodiment, the operation is performed using what is generally called an Oscar polishing machine. As shown in FIGS. 4 to 6, the polishing apparatus 5 includes an upper polishing dish 51, a lower polishing dish 52, and a substrate holding member 53.
　上研磨皿５１は、断面円形状のものから構成されており、その下面側に、研磨パッドを備えている。そして、このように構成された研磨パッドを有する上研磨皿５１は、水平方向（図示のＸ－Ｘ方向）に移動可能に構成されている。 The upper polishing dish 51 is composed of a circular cross section, and has a polishing pad on the lower surface side. The upper polishing plate 51 having the polishing pad configured as described above is configured to be movable in the horizontal direction (XX direction in the drawing).
　下研磨皿５２は、その上面側に、ガラス素板１０を収納する収納凹部５２ａを備えている。収納凹部５２ａは、円形状に所定深さで窪まされるようにして形成されているとともに、その底面は上研磨皿５１の下面と対向して水平状に配設されている。又、この収納凹部５２ａの底面には、研磨パッドが配設されている。この研磨パッドは、上記上研磨皿５１の研磨パッドと同構成のものである。 The lower polishing dish 52 is provided with a storage recess 52a for storing the glass base plate 10 on the upper surface side thereof. The storage recess 52 a is formed in a circular shape so as to be recessed at a predetermined depth, and its bottom surface is disposed horizontally so as to face the lower surface of the upper polishing dish 51. A polishing pad is disposed on the bottom surface of the storage recess 52a. This polishing pad has the same configuration as the polishing pad of the upper polishing plate 51.
　又、下研磨皿５２は、その下面側に、軸部５２ｂを備えており、この軸部５２ｂが回転させられることにより、その軸心回りに回転するように構成されている。 Further, the lower polishing dish 52 is provided with a shaft portion 52b on the lower surface side thereof, and is configured to rotate around its axis when the shaft portion 52b is rotated.
　基板保持部材５３は、図４、図５（ｂ）に示すように厚さがガラス素板１０の厚さよりも薄い円筒状のもの（この実施形態では、内径６５ｍｍ、外形６７ｍｍ、厚さ０．５ｍｍ）から構成され、その孔５３ａにガラス素板１０を入れ得るようになっている。 As shown in FIGS. 4 and 5B, the substrate holding member 53 has a cylindrical shape whose thickness is thinner than the thickness of the glass base plate 10 (in this embodiment, the inner diameter is 65 mm, the outer diameter is 67 mm, the thickness is 0. 5 mm), and the glass base plate 10 can be put in the hole 53a.
　そして、この基板保持部材５３の孔５３ａに入れられたガラス素板１０が、図５（ａ）に示すように、複数、下研磨皿５２の収納凹部５２ａに置かれるように配設されるとともに、図４、図６（ｂ）に示すように、上研磨皿５１が収納凹部５２ａの全体を上方側から覆うように配設される。この実施形態では、研磨装置５は、１００枚のガラス素板１０を下研磨皿５２の収納凹部５２ａに配置できるように構成されており、一回の処理（１バッチ）で１００枚のガラス素板１０を同時に研磨処理できるようになっている。 A plurality of glass base plates 10 placed in the holes 53a of the substrate holding member 53 are disposed so as to be placed in the storage recesses 52a of the lower polishing dish 52, as shown in FIG. 4 and FIG. 6B, the upper polishing dish 51 is disposed so as to cover the entire storage recess 52a from above. In this embodiment, the polishing apparatus 5 is configured such that 100 glass base plates 10 can be disposed in the storage recess 52a of the lower polishing plate 52, and 100 glass base plates are processed in one process (one batch). The plate 10 can be polished simultaneously.
　そして、この状態から、研磨液が供給されながら、図６（ａ）、（ｃ）に示すように、上研磨皿５１が水平方向に往復動し、下研磨皿５２が図５（ａ）の時計方向に回転する。これにより、ガラス素板１０の上側になった表面が上研磨皿５１の研磨パッドにより、下側になった裏面が下研磨皿５２の研磨パッドにより、夫々研磨される。 Then, as shown in FIGS. 6A and 6C, while the polishing liquid is supplied from this state, the upper polishing dish 51 reciprocates in the horizontal direction, and the lower polishing dish 52 moves as shown in FIG. 5A. Rotate clockwise. As a result, the upper surface of the glass base plate 10 is polished by the polishing pad of the upper polishing dish 51 and the lower surface of the glass base plate 10 is polished by the polishing pad of the lower polishing dish 52.
　この精密研磨工程では、前述したように、情報記録媒体用ガラス基板１０ａから製造された情報記録媒体をディスク装置に装着した場合において、ディスク装置のヘッドの低浮上化、高速回転への対応が容易になり、安定して記録・再生を行なうことができ、ヘッドと情報記録媒体との接触による記録・再生のエラーの危険性の少ないものにできるという理由から、外周ＴＩＲが０．７μｍ以下で、内周ＴＩＲが０．２μｍ以下になるように、ガラス素板１０を研磨加工することが好ましい。 In this precision polishing process, as described above, when an information recording medium manufactured from the information recording medium glass substrate 10a is mounted on a disk device, the head of the disk device can be easily lowered and can cope with high-speed rotation. Therefore, the outer periphery TIR is 0.7 μm or less because the recording / reproduction can be performed stably and the risk of recording / reproduction errors due to the contact between the head and the information recording medium can be reduced. The glass base plate 10 is preferably polished so that the inner circumference TIR is 0.2 μm or less.
　これにより、図１に示す情報記録媒体用ガラス基板１０ａを形成できる。形成された情報記録媒体用ガラス基板１０ａは、最終洗浄工程で洗浄され、付着物が落とされる。 Thereby, the glass substrate 10a for information recording media shown in FIG. 1 can be formed. The formed information recording medium glass substrate 10a is cleaned in the final cleaning step, and the deposits are removed.
　尚、精密研磨工程で用いる研磨装置は、上記研磨装置５を用いて行なう形態のものに限らず、他の研磨装置、例えば上記ラッピング工程で使用した研削装置１を、上記ダイヤモンドシート４を研磨パッドに交換等して、用いて行なうこともでき、適宜変更できる。又、上記第１ラッピング工程、第２ラッピング工程、粗研磨工程についても、研磨パッドを交換等して上記研磨装置５を用いて行なうことができるが、他の研磨装置を用いて行なうこともでき、適宜変更できる。 The polishing apparatus used in the precision polishing step is not limited to the one that is performed using the polishing apparatus 5, and other polishing apparatuses, for example, the grinding apparatus 1 used in the lapping process, and the diamond sheet 4 as a polishing pad are used. It can also be used by exchanging them with each other, and can be changed as appropriate. Further, the first lapping step, the second lapping step, and the rough polishing step can also be performed using the polishing apparatus 5 by exchanging the polishing pad, but can also be performed using other polishing apparatuses. Can be changed as appropriate.
　また、上記実施形態では、ラッピング工程を、第１ラッピング工程と第２ラッピング工程との２つから構成したが、例えばラッピング工程を、１つ又は３つ以上の工程から構成することもでき、適宜変更できる。 Moreover, in the said embodiment, although the lapping process was comprised from two, a 1st lapping process and a 2nd lapping process, for example, a lapping process can also be comprised from 1 or 3 or more processes, and is suitably Can be changed.
　以上説明したように、本実施形態によれば、研削部材が目詰まりを起こすおそれが少なく、ラッピング工程後のガラス素板のＴＩＲを一定値以下にしてＴＩＲの良好な情報記録媒体用ガラス基板を得ることができる。 As described above, according to the present embodiment, there is little risk of clogging of the grinding member, and the glass substrate for an information recording medium having a good TIR by setting the TIR of the glass base plate after the lapping step to a certain value or less. Obtainable.
　上記情報記録媒体用ガラス基板の製造方法の技術的特徴をまとめると下記のようになる。 The technical characteristics of the method for manufacturing the glass substrate for information recording medium are summarized as follows.
　情報記録媒体用ガラス基板の製造方法は、ガラス素板の表面を、研削装置と研削液とを用いてラッピング加工するラッピング工程を含む情報記録媒体用ガラス基板の製造方法であって、上記ラッピング工程で、上記研削液を、カルシウムとマグネシウムとの含有量が総量で常時５ｍｇ／Ｌ以下にして、ガラス素板の半径をｒ１としたときにガラス素板の中心から０．７５×ｒ１の位置で周方向のＴＩＲをトラック１周分測定した外周ＴＩＲが１．４μｍ以下、ガラス素板の半径をｒ１としガラス素板の貫通穴の半径をｒ２としたときにガラス素板の中心から（２×ｒ２＋ｒ１）／３の位置で周方向のＴＩＲをトラック１周分測定した内周ＴＩＲが０．７μｍ以下になるように、上記ガラス素板をラッピング加工することを特徴とする。 A method for producing a glass substrate for information recording medium is a method for producing a glass substrate for information recording medium, comprising a lapping step of lapping the surface of a glass base plate using a grinding apparatus and a grinding liquid, wherein the lapping step In the above grinding fluid, the total content of calcium and magnesium is always 5 mg / L or less, and the radius of the glass base plate is set to r1, at a position of 0.75 × r1 from the center of the glass base plate. When the TIR in the circumferential direction is measured by one track, the outer periphery TIR is 1.4 μm or less, the radius of the glass base plate is r1, and the radius of the through hole of the glass base plate is r2, from the center of the glass base plate (2 × The glass base plate is lapped so that an inner circumference TIR obtained by measuring a circumferential TIR for one track at a position of r2 + r1) / 3 is 0.7 μm or less.
　この構成によれば、研削液を、カルシウムとマグネシウムとの含有量が総量で常時５ｍｇ／Ｌ以下になるようにして、外周ＴＩＲが１．４μｍ以下、内周ＴＩＲが０．７μｍ以下になるようにラッピング加工を行なうため、ラッピング工程後に行なわれる精密研磨工程等の後工程を経て得られた情報記録媒体用ガラス基板の平坦度を良好にできる。 According to this configuration, the grinding liquid is set so that the total content of calcium and magnesium is always 5 mg / L or less, so that the outer periphery TIR is 1.4 μm or less and the inner periphery TIR is 0.7 μm or less. Since the lapping process is performed, the flatness of the glass substrate for an information recording medium obtained through a subsequent process such as a precision polishing process performed after the lapping process can be improved.
　他の一態様は、上述の情報記録媒体用ガラス基板の製造方法において、上記研削液を、カルシウムとマグネシウムとの含有量が総量で１ｍｇ／Ｌ以下の水で希釈する工程を含むことを特徴とする。 Another aspect is characterized in that, in the method for producing a glass substrate for an information recording medium, the grinding liquid is diluted with water having a total content of calcium and magnesium of 1 mg / L or less. To do.
　この構成によれば、上記研削液を、カルシウムとマグネシウムとの含有量が総量で１ｍｇ／Ｌ以下の水で希釈する工程を含むため、例えば研削液中のカルシウムとマグネシウムの量が非常に少ない状態からラッピング工程を開始できるので、研削部材の目詰まりを抑えて平坦度の低下を抑えることができる。 According to this configuration, since the grinding fluid includes a step of diluting with water having a total content of calcium and magnesium of 1 mg / L or less, for example, the amount of calcium and magnesium in the grinding fluid is very small. Since the lapping process can be started from this, clogging of the grinding member can be suppressed, and a decrease in flatness can be suppressed.
　他の一態様は、上述の情報記録媒体用ガラス基板の製造方法において、上記研削装置として、金属イオン除去フィルタを備えているものを用いることを特徴とする。 Another aspect is characterized in that, in the above-described method for manufacturing a glass substrate for an information recording medium, the grinding apparatus is provided with a metal ion removal filter.
　この構成によれば、研削装置として、金属イオン除去フィルタを備えているものを用いるため、ラッピング加工に際して研削液中に、ラッピング加工の対象物であるガラス素板に含まれるカルシウムやマグネシウムの成分が出ても、研削液中のカルシウムとマグネシウムとの含有量を総量で常時５ｍｇ／Ｌ以下に維持できる。 According to this configuration, since a grinding apparatus equipped with a metal ion removal filter is used, the components of calcium and magnesium contained in the glass base plate that is the object of the lapping process are included in the grinding liquid during the lapping process. Even if it comes out, the total content of calcium and magnesium in the grinding fluid can be maintained at 5 mg / L or less at all times.
　他の一態様は、上述の情報記録媒体用ガラス基板の製造方法において、上記研削液を、カルシウムとマグネシウムとの含有量が総量で常時３ｍｇ／Ｌ以下になるようにしてラッピング加工を行なうことを特徴とする。 Another aspect is that in the above-described method for producing a glass substrate for an information recording medium, the grinding liquid is lapped so that the total content of calcium and magnesium is always 3 mg / L or less. Features.
　この構成によれば、より一層、研削部材の目詰まりを起こし難くできる。 This configuration can further prevent clogging of the grinding member.
　他の一態様は、上述の情報記録媒体用ガラス基板の製造方法において、上記研削液を、セリウムの含有量が常時１０ｍｇ／Ｌ以下になるようにしてラッピング加工を行なうことを特徴とする。 Another aspect is characterized in that, in the above-described method for producing a glass substrate for an information recording medium, the grinding liquid is lapped so that the cerium content is always 10 mg / L or less.
　研削液に含まれるセリウムの量が１０ｍｇ／Ｌを超えると、その場合も、研削部材に目詰まりを起こして研削面へのスクラッチの発生、或いは研削面の平坦度が悪くなり、又、研削部材の劣化を早めるおそれが高くなる。そこで、上記のようにセリウムの含有量が常時１０ｍｇ／Ｌ以下になるようにして行なえば、研削部材に目詰まりを抑えることができる。これにより、研削面へのスクラッチの発生を抑えることができるとともに、研削面の平坦度が悪くなるのを抑えることができる。しかも、研削部材の劣化を抑えることができ、低コストで製造できる。 If the amount of cerium contained in the grinding fluid exceeds 10 mg / L, the grinding member will be clogged and scratches will occur on the grinding surface, or the flatness of the grinding surface will deteriorate. There is a high risk of accelerating deterioration. Therefore, if the cerium content is always 10 mg / L or less as described above, clogging of the grinding member can be suppressed. Thereby, generation | occurrence | production of the scratch to a grinding surface can be suppressed, and it can suppress that the flatness of a grinding surface deteriorates. In addition, deterioration of the grinding member can be suppressed and manufacturing can be performed at low cost.
　他の一態様は、上述の情報記録媒体用ガラス基板の製造方法において、上記ラッピング工程を経た後、ガラス素板の表面を、研磨装置を用いて研磨加工する精密研磨工程を含み、上記精密研磨工程で、外周ＴＩＲが０．７μｍ以下で、内周ＴＩＲが０．２μｍ以下になるようにガラス素板を研磨加工することを特徴とする。 Another aspect includes a precision polishing step in which the surface of the glass base plate is polished using a polishing apparatus after the lapping step in the method for manufacturing a glass substrate for an information recording medium. In the process, the glass base plate is polished so that the outer periphery TIR is 0.7 μm or less and the inner periphery TIR is 0.2 μm or less.
　この構成によれば、ガラス素板を研磨加工して得られる情報記録媒体用ガラス基板は、外周ＴＩＲが０．７μｍ以下で、内周ＴＩＲが０．２μｍ以下になるため、情報記録媒体用ガラス基板から製造された情報記録媒体をディスク装置に装着した場合において、ディスク装置のヘッドの低浮上化、高速回転への対応が容易になり、安定して記録・再生を行なうことができ、ヘッドと情報記録媒体との接触による記録・再生のエラーの危険性の少ないものにできる。又、内周ＴＩＲが０．２μｍ以下にすることで、例えば情報記録媒体用ガラス基板から製造された情報記録媒体をディスク装置にクランプ機構によって装着する場合でもそのクランプによって発生する情報記録媒体の歪を少なくでき、ヘッドと情報記録媒体との接触をより一層確実に防止できる。 According to this configuration, the information recording medium glass substrate obtained by polishing the glass base plate has an outer peripheral TIR of 0.7 μm or less and an inner peripheral TIR of 0.2 μm or less. When an information recording medium manufactured from a substrate is mounted on a disk device, the head of the disk device can be lowered and the high-speed rotation can be easily handled, and recording and reproduction can be performed stably. The risk of recording / reproducing errors due to contact with the information recording medium can be reduced. Further, by setting the inner circumference TIR to 0.2 μm or less, for example, even when an information recording medium manufactured from a glass substrate for information recording medium is mounted on a disk device by a clamp mechanism, distortion of the information recording medium caused by the clamp And the contact between the head and the information recording medium can be more reliably prevented.
　他の一態様は、上述の情報記録媒体用ガラス基板の製造方法において、上記ガラス素板として、ＳｉＯ２：５５～７５質量％、Ａｌ２Ｏ３：５～１８質量％、Ｌｉ２Ｏ：１～１０質量％、Ｎａ２Ｏ：３～１５質量％、Ｋ２Ｏ：０．１～５質量％、但し、Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏの総量：１０～２５質量％、ＭｇＯ：０．１～５質量％、ＣａＯ：０．１～５質量％、ＺｒＯ２：０～８質量％（０を含む）であり、（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ）に対する（ＭｇＯ＋ＣａＯ）の質量比が、０．１０≦（ＭｇＯ＋ＣａＯ）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ）≦０．８０の範囲にあるガラス組成のものを用いることを特徴とする。 Another aspect is that in the above-described method for manufacturing a glass substrate for an information recording medium, the glass base plate is composed of SiO 2 : 55 to 75 mass%, Al 2 O 3 : 5 to 18 mass%, Li 2 O: 1 To 10% by mass, Na 2 O: 3 to 15% by mass, K 2 O: 0.1 to 5% by mass, provided that the total amount of Li 2 O + Na 2 O + K 2 O: 10 to 25% by mass, MgO: 0.1 To 5 mass%, CaO: 0.1 to 5 mass%, ZrO 2 : 0 to 8 mass% (including 0), and the mass ratio of (MgO + CaO) to (Li 2 O + Na 2 O + K 2 O) is 0 10 ≦ (MgO + CaO) / (Li 2 O + Na 2 O + K 2 O) ≦ 0.80 is used.
　この構成によれば、ガラス素板として、上記範囲のガラス組成のものを用いるため、ガラス素板が適度な耐熱性を持ち、例えば化学強化を行う場合でも化学強化工程中における熱変形を抑えることができる。しかも、化学強化工程中におけるイオン交換が均一に行なわれ、ガラス素板表面に均等な圧縮応力を働かせることが出来、ガラス素板の平坦度が悪くなるのを抑えることができる。従って、例えばこの化学強化工程後に研磨加工する場合に、研磨加工により化学強化層（圧縮応力層）の平衡がくずれて平坦度が低下するのを抑えることができる。 According to this configuration, the glass base plate having a glass composition in the above range is used, so that the glass base plate has appropriate heat resistance, for example, even when chemical strengthening is performed, thermal deformation during the chemical strengthening process is suppressed. Can do. In addition, the ion exchange is uniformly performed during the chemical strengthening step, and a uniform compressive stress can be applied to the surface of the glass base plate, and deterioration of the flatness of the glass base plate can be suppressed. Therefore, for example, when polishing is performed after the chemical strengthening step, it is possible to prevent the flatness from being deteriorated due to the balance of the chemical strengthening layer (compressive stress layer) being lost due to the polishing.
　以下に、具体的に実施例を挙げて、本発明を更に詳しく説明する。ただし、本発明はこの実施例に限定されない。 Hereinafter, the present invention will be described in more detail with specific examples. However, the present invention is not limited to this embodiment.
　〔実施例１〕
　以下の組成を有する円盤状のガラス素板を製作した。実施例１に用いたガラス素板は、ＳｉＯ２：６４．５質量％、Ａｌ２Ｏ３：１４．９質量％、Ｌｉ２Ｏ：３．６質量％、Ｎａ２Ｏ：１１．２質量％、Ｋ２Ｏ：０．４質量％、ＭｇＯ：０．６質量％、ＣａＯ：１．６質量％、ＣｅＯ２：０．５質量％、ＺｒＯ２：２．０質量％、ＳｎＯ２：０．７質量％のものである。 [Example 1]
A disk-shaped glass base plate having the following composition was produced. The glass base plate used in Example 1 is SiO 2 : 64.5% by mass, Al 2 O 3 : 14.9% by mass, Li 2 O: 3.6% by mass, Na 2 O: 11.2% by mass. , K 2 O: 0.4 mass%, MgO: 0.6 mass%, CaO: 1.6 mass%, CeO 2 : 0.5 mass%, ZrO 2 : 2.0 mass%, SnO 2 : 0. 7% by mass.
　そして、製作した上記円盤状のガラス素板を、上記金属イオン除去フィルタ８を備えた研削装置１を用いるとともに、カルシウムとマグネシウムの総量が１ｍｇ／Ｌ以下である水で研削液を希釈し、研削液中のカルシウムとマグネシウムの総量を常時３ｍｇ／Ｌ以下、セリウムの量を１０ｍｇ／Ｌ以下に保つようにして、研削した。 Then, the manufactured disc-shaped glass base plate is ground by using the grinding apparatus 1 provided with the metal ion removing filter 8 and diluting the grinding liquid with water in which the total amount of calcium and magnesium is 1 mg / L or less. The total amount of calcium and magnesium in the liquid was always 3 mg / L or less, and the amount of cerium was kept at 10 mg / L or less for grinding.
　又、第１ラッピング工程では、粒度が９μｍのダイヤモンドシート４を使用し、第２ラッピング工程では、粒度が４μｍのダイヤモンドシート４を使用した。 In the first lapping step, a diamond sheet 4 having a particle size of 9 μm was used, and in the second lapping step, a diamond sheet 4 having a particle size of 4 μm was used.
　そして、第２ラッピング工程を終了した２００バッチ目の１つのガラス素板の内周ＴＩＲ及び外周ＴＩＲを夫々測定した（図７、実施例１）。又、第２ラッピング工程を終了した１０００バッチ目の１つのガラス素板の内周ＴＩＲ及び外周ＴＩＲを夫々測定した（図７、実施例１）。 Then, the inner circumference TIR and the outer circumference TIR of one glass base plate of the 200th batch after the second lapping step were measured (FIG. 7, Example 1). Further, the inner circumference TIR and the outer circumference TIR of one glass base plate of the 1000th batch after the second lapping step were measured (FIG. 7, Example 1).
　又、第２ラッピング工程後のガラス素板を精密研磨工程で研磨して形成した２００バッチ目の１つの情報記録媒体用ガラス基板（上記第２ラッピング工程を終了した２００バッチ目のガラス素板と同じもの）の内周ＴＩＲ及び外周ＴＩＲを夫々測定した（図７、実施例１）。更に、１０００バッチ目の１つの情報記録媒体用ガラス基板（上記第２ラッピング工程を終了した１０００バッチ目のガラス素板と同じもの）の内周ＴＩＲ及び外周ＴＩＲを夫々測定した（図７、実施例１）。 Further, one 200-th batch glass substrate for information recording medium formed by polishing the glass base plate after the second lapping step in the precision polishing step (the 200th batch glass base plate after the completion of the second lapping step) The same inner circumference TIR and outer circumference TIR were measured (FIG. 7, Example 1). Furthermore, the inner circumference TIR and the outer circumference TIR of one glass substrate for an information recording medium in the 1000th batch (the same as the 1000th batch glass blank after the second lapping step) were measured (FIG. 7, implementation). Example 1).
　〔実施例２〕
　上記実施例１と同じ組成の円盤状のガラス素板について、カルシウムとマグネシウムの総量が１ｍｇ／Ｌ以下である水で研削液を希釈し、研削液中のカルシウムとマグネシウムの総量を３ｍｇ／Ｌ～５ｍｇ／Ｌ以下、セリウムの量を１０ｍｇ／Ｌ以下に保つようにして研削した。その他は、実施例１と同じ条件で行なった。 [Example 2]
For the disk-shaped glass base plate having the same composition as in Example 1, the grinding fluid is diluted with water whose total amount of calcium and magnesium is 1 mg / L or less, and the total amount of calcium and magnesium in the grinding fluid is 3 mg / L to Grinding was performed so that the amount was 5 mg / L or less and the amount of cerium was 10 mg / L or less. The other conditions were the same as in Example 1.
　そして、実施例１の場合と同様に、第２ラッピング工程を終了した２００バッチ目、１０００バッチ目夫々のガラス素板の内周ＴＩＲ及び外周ＴＩＲを夫々測定するとともに、精密研磨工程で研磨して形成した２００バッチ目、１０００バッチ目の情報記録媒体用ガラス基板（上記第２ラッピング工程を終了した２００バッチ目、１０００バッチ目夫々のものと同じもの）の内周ＴＩＲ及び外周ＴＩＲを夫々測定した（図７、実施例２）。 Then, as in the case of Example 1, while measuring the inner circumference TIR and the outer circumference TIR of the glass base plates of the 200th batch and the 1000th batch after finishing the second lapping process, they were polished in the precision polishing process. The inner circumference TIR and outer circumference TIR of the formed 200th and 1000th batch information recording medium glass substrates (the same as the 200th and 1000th batches after the second lapping step) were measured, respectively. (FIG. 7, Example 2).
　〔比較例１〕
　又、比較例１として、上記実施例１と同じ組成の円盤状のガラス素板について、カルシウムとマグネシウムの総量が１ｍｇ／Ｌ以下である水で研削液を希釈し、研削液中のカルシウムとマグネシウムの総量を５ｍｇ／Ｌ以下に保つようにして研削した。セリウムの量は制御しなかった。 [Comparative Example 1]
Further, as Comparative Example 1, for a disk-shaped glass base plate having the same composition as in Example 1, the grinding fluid was diluted with water having a total amount of calcium and magnesium of 1 mg / L or less, and calcium and magnesium in the grinding fluid were diluted. The total amount of was ground at 5 mg / L or less. The amount of cerium was not controlled.
　そして、実施例１の場合と同様に、第２ラッピング工程を終了した２００バッチ目、１０００バッチ目夫々のガラス素板の内周ＴＩＲ及び外周ＴＩＲを夫々測定するとともに、精密研磨工程で研磨して形成した２００バッチ目、１０００バッチ目の情報記録媒体用ガラス基板（上記第２ラッピング工程を終了した２００バッチ目、１０００バッチ目夫々のものと同じもの）の内周ＴＩＲ及び外周ＴＩＲを夫々測定した（図７、比較例１）。 Then, as in the case of Example 1, while measuring the inner circumference TIR and the outer circumference TIR of the glass base plates of the 200th batch and the 1000th batch after finishing the second lapping process, they were polished in the precision polishing process. The inner circumference TIR and outer circumference TIR of the formed 200th and 1000th batch information recording medium glass substrates (the same as the 200th and 1000th batches after the second lapping step) were measured, respectively. (FIG. 7, Comparative Example 1).
〔比較例２〕
　比較例２として、上記実施例１と同じ組成の円盤状のガラス素板について、水道水で研削液を希釈した後、研削液を上記金属イオン除去フィルタを透過させるようにして研削液中のカルシウムとマグネシウムの総量を５ｍｇ／Ｌ以下、セリウムの量を１０ｍｇ／Ｌ以下に保ち研削した。 [Comparative Example 2]
As Comparative Example 2, for the disk-shaped glass base plate having the same composition as in Example 1, after diluting the grinding liquid with tap water, the grinding liquid is allowed to pass through the metal ion removal filter so that calcium in the grinding liquid is obtained. And the total amount of magnesium was kept at 5 mg / L or less, and the amount of cerium was kept at 10 mg / L or less for grinding.
　詳しくは、希釈した水道水は、カルシウムとマグネシウムの含有量が総量で１５ｍｇ／Ｌのものであり、希釈した直後の加工に供した研削液は、カルシウムとマグネシウムの含有量が総量で５ｍｇ／Ｌ以上であったが、その後（２回目以降）は、金属イオン除去フィルタを透過するため、研削液中のカルシウムとマグネシウムの総量が５ｍｇ／Ｌ以下、セリウムの量が１０ｍｇ／Ｌ以下になり、その状態で研削液を加工に供した。 Specifically, the diluted tap water has a total calcium and magnesium content of 15 mg / L, and the grinding fluid used for processing immediately after dilution has a total calcium and magnesium content of 5 mg / L. After that (after the second time), since it permeates the metal ion removal filter, the total amount of calcium and magnesium in the grinding fluid is 5 mg / L or less and the amount of cerium is 10 mg / L or less. The grinding fluid was used for processing in the state.
　そして、実施例１の場合と同様に、第２ラッピング工程を終了した２００バッチ目、１０００バッチ目夫々のガラス素板の内周ＴＩＲ及び外周ＴＩＲを夫々測定するとともに、精密研磨工程で研磨して形成した２００バッチ目、１０００バッチ目の情報記録媒体用ガラス基板（上記第２ラッピング工程を終了した２００バッチ目、１０００バッチ目夫々のものと同じもの）の内周ＴＩＲ及び外周ＴＩＲを夫々測定した（図７、比較例２）。 Then, as in the case of Example 1, while measuring the inner circumference TIR and the outer circumference TIR of the glass base plates of the 200th batch and the 1000th batch after finishing the second lapping process, they were polished in the precision polishing process. The inner circumference TIR and outer circumference TIR of the formed 200th and 1000th batch information recording medium glass substrates (the same as the 200th and 1000th batches after the second lapping step) were measured, respectively. (FIG. 7, comparative example 2).
　〔比較例３〕
　比較例３として、上記実施例１と同じ組成の円盤状のガラス素板について、カルシウムとマグネシウムの総量が１ｍｇ／Ｌ以下である水で研削液を希釈し、カルシウム、マグネシウム量を制御せず、セリウムの量を１０ｍｇ／Ｌ以下に保ち研削した。 [Comparative Example 3]
As Comparative Example 3, for the disk-shaped glass base plate having the same composition as in Example 1, the grinding fluid was diluted with water having a total amount of calcium and magnesium of 1 mg / L or less, and the amounts of calcium and magnesium were not controlled. The amount of cerium was kept at 10 mg / L or less for grinding.
　詳しくは、金属イオン除去フィルタを、キレート材を調整することによってセリウムだけを除去してカルシウム及びマグネシウムを透過できるようにしたものを用いることによってカルシウム、マグネシウム量を制御しないようにした。 Specifically, the amount of calcium and magnesium was not controlled by using a metal ion removing filter that was made to remove only cerium by adjusting a chelating material so that calcium and magnesium could permeate.
　従って、希釈した直後の加工に供した研削液は、カルシウムとマグネシウムの含有量が総量で５ｍｇ／Ｌ以下であったが、その後、ガラス素板に含まれたカルシウムとマグネシウムが研削液中に出てその含有量が徐々に増して総量で５ｍｇ／Ｌ以上になった。 Therefore, the total amount of calcium and magnesium contained in the grinding fluid used for processing immediately after dilution was 5 mg / L or less. Thereafter, calcium and magnesium contained in the glass base plate were released into the grinding fluid. The content gradually increased to a total amount of 5 mg / L or more.
　そして、実施例１の場合と同様に、第２ラッピング工程を終了した２００バッチ目、１０００バッチ目夫々のガラス素板の内周ＴＩＲ及び外周ＴＩＲを夫々測定するとともに、精密研磨工程で研磨して形成した２００バッチ目、１０００バッチ目の情報記録媒体用ガラス基板（上記第２ラッピング工程を終了した２００バッチ目、１０００バッチ目夫々のものと同じもの）の内周ＴＩＲ及び外周ＴＩＲを夫々測定した（図７、比較例３）。 Then, as in the case of Example 1, while measuring the inner circumference TIR and the outer circumference TIR of the glass base plates of the 200th batch and the 1000th batch after finishing the second lapping process, they were polished in the precision polishing process. The inner circumference TIR and outer circumference TIR of the formed 200th and 1000th batch information recording medium glass substrates (the same as the 200th and 1000th batches after the second lapping step) were measured, respectively. (FIG. 7, comparative example 3).
　〔比較例４〕
　比較例４として、上記実施例１と同じ組成の円盤状のガラス素板について、水道水で研削液を希釈し、カルシウム、マグネシウム量を制御しないで、セリウムの量を１０ｍｇ／Ｌ以下に保ち研削した。 [Comparative Example 4]
As Comparative Example 4, for a disk-shaped glass base plate having the same composition as in Example 1, the grinding liquid was diluted with tap water, and the amount of cerium was kept at 10 mg / L or less without controlling the amounts of calcium and magnesium. did.
　詳しくは、上記比較例２で用いた同じ水道水を用い、又、上記比較例３で用いたものと同じ金属イオン除去フィルタを用いてカルシウム、マグネシウム量を制御しないようにした。従って、希釈した直後の加工に供した研削液は、カルシウムとマグネシウムの含有量が総量で５ｍｇ／Ｌ以上であり、その後、ガラス素板に含まれたカルシウムとマグネシウムが研削液中に出てその含有量が徐々に増した。この場合も、カルシウムとマグネシウムの含有量が総量で５ｍｇ／Ｌ以上になるため、カルシウム及びマグネシウムが、研削液に含まれる脂肪酸或いはノニオン等と金属塩を生成して第１及び第２ダイヤモンドシート４の目詰まりを助長したと思われる。 Specifically, the same tap water used in Comparative Example 2 was used, and the same metal ion removal filter as that used in Comparative Example 3 was used so that the amounts of calcium and magnesium were not controlled. Therefore, the grinding fluid used for the processing immediately after dilution has a total content of calcium and magnesium of 5 mg / L or more, and then calcium and magnesium contained in the glass base plate come out into the grinding fluid. The content gradually increased. Also in this case, since the total content of calcium and magnesium is 5 mg / L or more, the calcium and magnesium produce metal salts with fatty acids or nonions contained in the grinding fluid to produce the first and second diamond sheets 4. It seems that it helped clogging.
　そして、実施例１の場合と同様に、第２ラッピング工程を終了した２００バッチ目、１０００バッチ目夫々のガラス素板の内周ＴＩＲ及び外周ＴＩＲを夫々測定するとともに、精密研磨工程で研磨して形成した２００バッチ目、１０００バッチ目の情報記録媒体用ガラス基板（上記第２ラッピング工程を終了した２００バッチ目、１０００バッチ目夫々のものと同じもの）の内周ＴＩＲ及び外周ＴＩＲを夫々測定した（図７、比較例４）。 Then, as in the case of Example 1, while measuring the inner circumference TIR and the outer circumference TIR of the glass base plates of the 200th batch and the 1000th batch after finishing the second lapping process, they were polished in the precision polishing process. The inner circumference TIR and outer circumference TIR of the formed 200th and 1000th batch information recording medium glass substrates (the same as the 200th and 1000th batches after the second lapping step) were measured, respectively. (FIG. 7, comparative example 4).
　〔比較例５〕
　比較例５として、上記実施例１と同じ組成の円盤状のガラス素板について、水道水で研削液を希釈し、金属イオン除去フィルタを用いずにカルシウム、マグネシウム、セリウム量を制御しないで研削した。従って、希釈した直後の加工に供した研削液は、カルシウムとマグネシウムの含有量が総量で５ｍｇ／Ｌ以上であり、その後、ガラス素板に含まれたカルシウムとマグネシウムとセリウムが研削液中に出てその含有量が徐々に増した。 [Comparative Example 5]
As Comparative Example 5, a disk-shaped glass base plate having the same composition as in Example 1 was diluted with tap water and ground without controlling the amounts of calcium, magnesium, and cerium without using a metal ion removal filter. . Therefore, the grinding fluid used for processing immediately after dilution has a total content of calcium and magnesium of 5 mg / L or more, and thereafter, calcium, magnesium and cerium contained in the glass base plate appear in the grinding fluid. The content gradually increased.
　そして、実施例１の場合と同様に、第２ラッピング工程を終了した２００バッチ目、１０００バッチ目夫々のガラス素板の内周ＴＩＲ及び外周ＴＩＲを夫々測定するとともに、精密研磨工程で研磨して形成した２００バッチ目、１０００バッチ目の情報記録媒体用ガラス基板（上記第２ラッピング工程を終了した２００バッチ目、１０００バッチ目夫々のものと同じもの）の内周ＴＩＲ及び外周ＴＩＲを夫々測定した（図７、比較例５）。 Then, as in the case of Example 1, while measuring the inner circumference TIR and the outer circumference TIR of the glass base plates of the 200th batch and the 1000th batch after finishing the second lapping process, they were polished in the precision polishing process. The inner circumference TIR and outer circumference TIR of the formed 200th and 1000th batch information recording medium glass substrates (the same as the 200th and 1000th batches after the second lapping step) were measured, respectively. (FIG. 7, comparative example 5).
　測定の結果は、実施例１及び２では、１０００バッチ目の第２ラッピング工程後のガラス素板の内周ＴＩＲの０．７μｍ以下で、外周ＴＩＲが１．４μｍ以下であり、精密研磨工程後の情報記録媒体用ガラス基板の内周ＴＩＲが０．２μｍ以下で、外周ＴＩＲが０．７μｍ以下であった。 As a result of the measurement, in Examples 1 and 2, the inner peripheral TIR of the glass base plate after the second lapping process of the 1000th batch is 0.7 μm or less and the outer peripheral TIR is 1.4 μm or less. The glass substrate for information recording medium had an inner circumference TIR of 0.2 μm or less and an outer circumference TIR of 0.7 μm or less.
　これに対し、比較例１では、１０００バッチ目の第２ラッピング工程後のガラス素板の内周ＴＩＲが０．７μｍ以下にならず、精密研磨工程後の情報記録媒体用ガラス基板の内周ＴＩＲが０．２μｍ以下にならなかった。 On the other hand, in Comparative Example 1, the inner circumference TIR of the glass base plate after the second lapping process of the 1000th batch does not become 0.7 μm or less, and the inner circumference TIR of the glass substrate for information recording medium after the precision polishing process. Was not less than 0.2 μm.
　又、比較例２では、２００バッチ目の第２ラッピング工程後のガラス素板の内周ＴＩＲが０．７μｍ以下にならず、精密研磨工程後の情報記録媒体用ガラス基板の内周ＴＩＲが０．２μｍ以下にならなかった。 In Comparative Example 2, the inner circumference TIR of the glass base plate after the second lapping process of the 200th batch does not become 0.7 μm or less, and the inner circumference TIR of the glass substrate for information recording medium after the precision polishing process is 0. It was not less than 2 μm.
　又、比較例３～５では、２００バッチ目及び１０００バッチ目夫々の第２ラッピング工程後のガラス素板の内周ＴＩＲが０．７μｍ以下にならず、精密研磨工程後の情報記録媒体用ガラス基板の内周ＴＩＲが０．２μｍ以下にならなかった。 In Comparative Examples 3 to 5, the inner circumference TIR of the glass base plate after the second lapping process in each of the 200th batch and the 1000th batch does not become 0.7 μm or less, and the glass for the information recording medium after the precision polishing process. The inner circumference TIR of the substrate did not become 0.2 μm or less.
　この出願は、２０１０年６月３０日に出願された日本国特許出願特願２０１０－１４８８５２を基礎とするものであり、その内容は、本願に含まれるものである。 This application is based on Japanese Patent Application No. 2010-148852 filed on June 30, 2010, the contents of which are included in the present application.
　本発明を表現するために、上述において図面を参照しながら実施形態を通して本発明を適切且つ十分に説明したが、当業者であれば上述の実施形態を変更および／または改良することは容易に為し得ることであると認識すべきである。したがって、当業者が実施する変更形態または改良形態が、請求の範囲に記載された請求項の権利範囲を離脱するレベルのものでない限り、当該変更形態または当該改良形態は、当該請求項の権利範囲に包括されると解釈される。 In order to express the present invention, the present invention has been properly and fully described through the embodiments with reference to the drawings. However, those skilled in the art can easily change and / or improve the above-described embodiments. It should be recognized that this is possible. Therefore, unless the modifications or improvements implemented by those skilled in the art are at a level that departs from the scope of the claims recited in the claims, the modifications or improvements are not covered by the claims. It is interpreted that it is included in
　本発明は、情報記録媒体用ガラス基板の製造方法の技術分野において、広範な産業上の利用可能性を有する。 The present invention has wide industrial applicability in the technical field of the method for producing a glass substrate for information recording media.

Claims (7)

  1. 　ガラス素板の表面を、研削装置と研削液とを用いてラッピング加工するラッピング工程を含む情報記録媒体用ガラス基板の製造方法であって、
    　上記ラッピング工程で、上記研削液を、カルシウムとマグネシウムとの含有量が総量で常時５ｍｇ／Ｌ以下にして、ガラス素板の半径をｒ１としたときにガラス素板の中心から０．７５×ｒ１の位置で周方向のＴＩＲをトラック１周分測定した外周ＴＩＲが１．４μｍ以下、ガラス素板の半径をｒ１としガラス素板の貫通穴の半径をｒ２としたときにガラス素板の中心から（２×ｒ２＋ｒ１）／３の位置で周方向のＴＩＲをトラック１周分測定した内周ＴＩＲが０．７μｍ以下になるように、上記ガラス素板をラッピング加工することを特徴とする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, comprising a lapping step of lapping the surface of a glass base plate using a grinding apparatus and a grinding liquid,
    In the lapping step, when the grinding fluid is always made to have a total content of calcium and magnesium of 5 mg / L or less and the radius of the glass base plate is r1, 0.75 × r1 from the center of the glass base plate. From the center of the glass base plate, when the outer periphery TIR of the circumferential direction TIR measured at one position is 1.4 μm or less, the radius of the glass base plate is r1, and the radius of the through hole of the glass base plate is r2. An information recording medium characterized in that the glass base plate is lapped so that an inner circumference TIR obtained by measuring a TIR in the circumferential direction at a position of (2 × r2 + r1) / 3 is 0.7 μm or less. Method for manufacturing glass substrate.
  2. 　上記研削液を、カルシウムとマグネシウムとの含有量が総量で１ｍｇ／Ｌ以下の水で希釈する工程を含むことを特徴とする請求項１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, comprising a step of diluting the grinding fluid with water having a total content of calcium and magnesium of 1 mg / L or less.
  3. 　上記研削装置として、金属イオン除去フィルタを備えているものを用いることを特徴とする請求項１又は２記載の情報記録媒体用ガラス基板の製造方法。 3. The method for producing a glass substrate for an information recording medium according to claim 1, wherein the grinding device is provided with a metal ion removal filter.
  4. 　上記研削液を、カルシウムとマグネシウムとの含有量が総量で常時３ｍｇ／Ｌ以下になるようにしてラッピング加工を行なうことを特徴とする請求項１～３の何れか一項に記載の情報記録媒体用ガラス基板の製造方法。 4. The information recording medium according to claim 1, wherein the grinding liquid is lapped so that the total content of calcium and magnesium is always 3 mg / L or less. Method for manufacturing glass substrate.
  5. 　上記研削液を、セリウムの含有量が常時１０ｍｇ／Ｌ以下になるようにしてラッピング加工を行なうことを特徴とする請求項１～４の何れか一項に記載の情報記録媒体用ガラス基板の製造方法。 5. The production of a glass substrate for an information recording medium according to claim 1, wherein the grinding liquid is lapped so that the cerium content is always 10 mg / L or less. Method.
  6. 　上記ラッピング工程を経た後、ガラス素板の表面を、研磨装置を用いて研磨加工する精密研磨工程を含み、
    　上記精密研磨工程で、外周ＴＩＲが０．７μｍ以下で、内周ＴＩＲが０．２μｍ以下になるようにガラス素板を研磨加工することを特徴とする請求項１～５の何れか一項に記載の情報記録媒体用ガラス基板の製造方法。     After passing through the lapping step, including a precision polishing step of polishing the surface of the glass base plate using a polishing apparatus,
    6. The glass substrate is polished in the precision polishing step so that the outer peripheral TIR is 0.7 μm or less and the inner peripheral TIR is 0.2 μm or less. The manufacturing method of the glass substrate for information recording media of description.
  7. 　上記ガラス素板として、ＳｉＯ２：５５～７５質量％、Ａｌ２Ｏ３：５～１８質量％、Ｌｉ２Ｏ：１～１０質量％、Ｎａ２Ｏ：３～１５質量％、Ｋ２Ｏ：０．１～５質量％、但し、Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏの総量：１０～２５質量％、ＭｇＯ：０．１～５質量％、ＣａＯ：０．１～５質量％、ＺｒＯ２：０～８質量％（０を含む）であり、（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ）に対する（ＭｇＯ＋ＣａＯ）の質量比が、０．１０≦（ＭｇＯ＋ＣａＯ）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ）≦０．８０の範囲にあるガラス組成のものを用いることを特徴とする請求項１～６の何れか一項に記載の情報記録媒体用ガラス基板の製造方法。 As the glass base plate, SiO 2 : 55 to 75% by mass, Al 2 O 3 : 5 to 18% by mass, Li 2 O: 1 to 10% by mass, Na 2 O: 3 to 15% by mass, K 2 O: 0.1-5% by mass, provided that the total amount of Li 2 O + Na 2 O + K 2 O: 10-25% by mass, MgO: 0.1-5% by mass, CaO: 0.1-5% by mass, ZrO 2 : 0 ~ a 8 mass% (including 0), the weight ratio of (Li 2 O + Na 2 O + K 2 O) for (MgO + CaO) is, 0.10 ≦ (MgO + CaO) / (Li 2 O + Na 2 O + K 2 O) ≦ 0. The method for producing a glass substrate for an information recording medium according to any one of claims 1 to 6, wherein a glass composition having a glass composition in the range of 80 is used.
PCT/JP2011/003224 2010-06-30 2011-06-08 Method for manufacturing glass substrate for information recording media WO2012001884A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10110183A (en) * 1996-10-04 1998-04-28 Kyoeisha Chem Co Ltd Grinding agent
JP2006088320A (en) * 2004-08-27 2006-04-06 Showa Denko Kk Substrate for magnetic disk and manufacturing method of magnetic disk
JP2009076167A (en) * 2007-09-22 2009-04-09 Konica Minolta Opto Inc Method of manufacturing glass substrate for information recording medium, glass substrate for information recording medium and magnetic recording medium

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10110183A (en) * 1996-10-04 1998-04-28 Kyoeisha Chem Co Ltd Grinding agent
JP2006088320A (en) * 2004-08-27 2006-04-06 Showa Denko Kk Substrate for magnetic disk and manufacturing method of magnetic disk
JP2009076167A (en) * 2007-09-22 2009-04-09 Konica Minolta Opto Inc Method of manufacturing glass substrate for information recording medium, glass substrate for information recording medium and magnetic recording medium

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