WO2014103284A1 - Procédé pour la production de substrat en verre pour support d'enregistrement d'informations - Google Patents

Procédé pour la production de substrat en verre pour support d'enregistrement d'informations Download PDF

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Publication number
WO2014103284A1
WO2014103284A1 PCT/JP2013/007549 JP2013007549W WO2014103284A1 WO 2014103284 A1 WO2014103284 A1 WO 2014103284A1 JP 2013007549 W JP2013007549 W JP 2013007549W WO 2014103284 A1 WO2014103284 A1 WO 2014103284A1
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WIPO (PCT)
Prior art keywords
polishing
base plate
glass substrate
glass
information recording
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PCT/JP2013/007549
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English (en)
Japanese (ja)
Inventor
明広 坂本
塚田　和也
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Hoya株式会社
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Publication of WO2014103284A1 publication Critical patent/WO2014103284A1/fr

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    • 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
    • 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

Definitions

  • the present invention relates to a method for producing a glass substrate for an information recording medium.
  • a typical example of such an information recording apparatus is a hard disk drive apparatus.
  • a hard disk drive device is a device that magnetically records (writes) information on a magnetic disk (hard disk) as an information recording medium having a recording layer formed on a substrate, and reproduces (reads) the recorded information. is there.
  • a so-called substrate a glass substrate is preferably used.
  • the hard disk drive device keeps the magnetic head floating above the magnetic disk without contacting the magnetic disk when information is recorded on or read from the magnetic disk. It is known that the recording density can be improved by reducing the flying height of the magnetic head. In recent years, the recording density of magnetic disks has been increased, and the flying height of the magnetic head has been reduced to about several nanometers. For these reasons, in order to further reduce the flying height of the magnetic head and increase the recording density, it is required that the glass substrate for the information recording medium has high smoothness.
  • Such a glass substrate for an information recording medium is manufactured by cutting a glass base plate (glass blank) obtained from molten glass and then polishing it. Specifically, a rough polishing process is first performed on the cut glass base plate with a polishing liquid containing cerium oxide as an abrasive, and further polished with a polishing liquid containing colloidal silica as an abrasive. Examples include a method of performing a precision polishing step. Thus, the glass substrate for information recording media with high smoothness was obtained by performing grinding
  • cerium oxide contains a rare earth element (rare earth), and thus there is a problem in terms of price and stable supply. It is possible.
  • Patent Document 1 describes a method for producing a glass substrate for a magnetic recording medium comprising a step of polishing using a polishing liquid containing abrasive grains having an average particle size of 5 to 3000 nm other than cerium oxide particles such as silica particles and zirconia particles. Has been.
  • Patent Document 1 it is possible to remove a work-affected layer generated on a main plane of a glass substrate during processing such as chamfering or grinding of the main surface without using cerium oxide abrasive grains, and a main plane having high smoothness. It is disclosed that a glass substrate for a magnetic recording medium having the following can be obtained.
  • examples of the polishing composition using an abrasive other than cerium oxide such as zirconium oxide as the abrasive grains include the techniques described in Patent Documents 2 to 5.
  • JP 2012-209010 A Special table 2003-510446 gazette Japanese Patent Laid-Open No. 2005-14204 JP 2005-23313 A JP 2005-34986 A
  • the present invention is a method for producing a glass substrate for information recording medium, which can produce a sufficiently high quality glass substrate for information recording medium while ensuring a high polishing rate without using cerium oxide as an abrasive.
  • the purpose is to provide.
  • One aspect of the present invention includes a polishing step of polishing the surface of the glass base plate by relatively moving the glass base plate and the polishing pad in a state where the polishing liquid is supplied onto the glass base plate.
  • the polishing liquid contains a mechanical abrasive and a cellulose-based additive, the average particle diameter of the mechanical abrasive is 0.5 to 1.5 ⁇ m, and the weight-average molecular weight of the cellulose-based additive is The method for producing a glass substrate for an information recording medium, characterized in that it is 20000-75000.
  • FIG. 1 is a schematic cross-sectional view showing an example of a polishing apparatus used in a polishing step in a method for manufacturing a glass substrate for an information recording medium according to an embodiment of the present invention.
  • FIG. 2 is a top view showing a glass base plate used in the method for manufacturing a glass substrate for an information recording medium according to an embodiment of the present invention.
  • FIG. 3 is a partial cross-sectional perspective view showing a magnetic disk as an example of an information recording medium using the glass substrate for information recording medium manufactured by the method for manufacturing the glass substrate for information recording medium according to one embodiment of the present invention. It is.
  • An abrasive other than cerium oxide is a mechanical abrasive that mainly exhibits a mechanical polishing action rather than a chemical mechanical polishing action.
  • the polishing compositions described in Patent Documents 2 to 5 describe that hydroxyalkylalkylcellulose or the like is contained as an edge sag preventing agent. Since such an edge sag preventing agent needs to exert a thickening action, the hydroxyalkyl alkyl cellulose contained as an edge sag preventing agent has a relatively high molecular weight that can exert a thickening action. It is thought that.
  • polishing compositions described in Patent Documents 2 to 5 are used for polishing an aluminum magnetic disk substrate, and are not considered to be suitable for polishing a glass base plate.
  • the glass base plate and the polishing pad are relatively moved in a state where the polishing liquid is supplied onto the glass base plate.
  • a polishing liquid having a weight-average molecular weight of 20000 to 75000 is used.
  • the average particle size of the mechanical abrasive is relatively small, 0.5 to 1.5 ⁇ m. If polishing is performed with such a relatively small abrasive, it is possible to suppress the occurrence of scratches and end-face sagging, but it is considered that a sufficiently high polishing rate cannot be ensured. Therefore, it is considered that a plurality of the mechanical abrasives are gathered by containing the cellulose-based additive. It is considered that the aggregated mechanical abrasive has a large particle size in the aggregated state and can increase the polishing rate. In addition, this aggregated state is considered to be a relatively weak aggregated state that is dispersed when a strong pressure is applied.
  • the manufacturing method of the glass substrate for information recording media according to the present embodiment is not particularly limited as long as it includes the polishing step.
  • the polishing step is not particularly limited except that the polishing step is as described above, and any conventional manufacturing method may be used.
  • it is common to perform multiple times of polishing including a rough polishing step and a precision polishing step as a polishing step for polishing the main surface.
  • the polishing process according to the present embodiment is performed as the rough polishing process, and a precision polishing process is separately performed.
  • the polishing step is a rough polishing step, and further includes a precision polishing step of precisely polishing the surface of the glass base plate polished in the rough polishing step. It is preferable to provide. By doing so, a sufficiently high-quality glass base plate can be obtained as the glass base plate after the rough polishing step in the polishing step. In addition, a high-quality glass substrate for an information recording medium can be obtained.
  • polishing step in the method for manufacturing the glass substrate for information recording medium according to the present embodiment will be described.
  • the polishing step is not particularly limited as long as it is the above-described polishing step. Specifically, it is a step of polishing the surface of the glass base plate by relatively moving the glass base plate and the polishing pad while supplying the polishing liquid onto the glass base plate.
  • the polishing liquid contains a mechanical abrasive and a cellulose additive, and the average particle diameter of the mechanical abrasive is 0.5 to 1.5 ⁇ m.
  • the weight average of the cellulose additive A polishing liquid having a molecular weight of 20000 to 75000 is used.
  • the average particle diameter here is a median diameter (D50), and can be calculated from, for example, a particle size distribution measured using a laser diffraction scattering method or the like.
  • the weight average molecular weight can be measured using gel permeation chromatography or the like.
  • the polishing liquid used in this polishing step is not particularly limited as long as it is the above-described polishing liquid.
  • the abrasive contained in the polishing liquid includes a mechanical abrasive.
  • the mechanical abrasive is an abrasive other than cerium oxide, and is a mechanical abrasive that mainly exhibits a mechanical polishing action rather than a chemical mechanical polishing action.
  • Examples of the mechanical abrasive include aluminum oxide (alumina), zirconium oxide (zirconia), silicon carbide, titanium oxide (titania), particles of iron oxide (abrasive grains), and the like.
  • a natural abrasive such as corundum can be used. Of these, zirconium oxide and aluminum oxide are preferable as the mechanical abrasive.
  • each of the above abrasives may be used alone, or two or more kinds may be used in combination.
  • the abrasive contained in the polishing liquid may contain cerium oxide in addition to the mechanical abrasive, but the abrasive is preferably made of a mechanical abrasive.
  • the abrasive is mainly composed of a mechanical abrasive.
  • the average particle diameter of the mechanical abrasive is 0.5 to 1.5 ⁇ m, preferably 0.8 to 1.2 ⁇ m. If the mechanical abrasive is too small, even in the production method according to this embodiment, the polishing rate tends not to be sufficiently increased. This is considered to be because a sufficient polishing rate cannot be ensured even if the mechanical abrasive is aggregated by containing the cellulose-based additive. On the other hand, if the mechanical abrasive is too large, the occurrence of scratches and the like cannot be sufficiently suppressed, and the quality of the finally obtained glass substrate tends to deteriorate. From these things, if the average particle diameter of the mechanical abrasive is within the above range, in the production method according to the present embodiment, a sufficiently high-quality glass substrate is obtained while ensuring a high polishing rate. Can do.
  • the content of the mechanical abrasive is preferably 6 to 20% by mass, and more preferably 10 to 15% by mass with respect to the total amount of the polishing liquid.
  • the content of the mechanical abrasive is within the above range, a higher-quality glass substrate can be obtained while increasing the polishing rate.
  • the cellulose additive is not particularly limited as long as it is a cellulose additive having a weight average molecular weight of 20000 to 75000. With such a cellulose-based additive, it is considered that relatively weak aggregation of the mechanical abrasive can be promoted while suppressing the viscosity of the polishing liquid from being excessively increased. Further, as described above, the weight average molecular weight of the cellulose-based additive is 20000-75000, preferably 25000-50000. If the weight average molecular weight of the cellulose-based additive is within the above range, a sufficiently high-quality glass substrate can be obtained while ensuring a high polishing rate in the production method according to this embodiment. This is considered to be because the aggregated state of the mechanical abrasive can be brought into a suitable state.
  • the cellulose-based additive examples include alkyl celluloses such as methylcellulose (MC), hydroxypropyls such as hydroxypropylmethylcellulose (HPMC), hydroxyethylmethylcellulose (HEMC), hydroxyethylcellulose (HEC), and hydroxypropylcellulose (HPC).
  • alkyl celluloses such as methylcellulose (MC), hydroxypropyls such as hydroxypropylmethylcellulose (HPMC), hydroxyethylmethylcellulose (HEMC), hydroxyethylcellulose (HEC), and hydroxypropylcellulose (HPC).
  • carboxyalkyl celluloses such as alkyl cellulose and carboxymethyl cellulose (CMC).
  • MC, HPMC, and CMC are preferable as the cellulose-based additive.
  • each of the cellulose-based additives exemplified above may be used alone, or two or more types may be used in combination.
  • the content of the cellulose-based additive is preferably 1 to 5% by mass, more preferably 2 to 3% by mass with respect to the mechanical abrasive. If content of the said cellulose type additive exists in the said range, a higher quality glass substrate can be obtained, raising polishing rate more. That is, the effect of adding the cellulose additive can be suitably exhibited.
  • the object to be polished (object to be polished) in the polishing step is not particularly limited as long as it is a glass base plate that can be a glass substrate for an information recording medium by performing a polishing process or the like.
  • soda lime glass mainly composed of SiO 2 , Na 2 O, and CaO, SiO 2 , Al 2 O 3 , and R 1 2 O (in the formula, R 1 represents K, Na, or Li.)
  • the glass composition is 55 to 75% by mass of SiO 2 , 5 to 18% by mass of Al 2 O 3 , 1 to 10% by mass of Li 2 O, and 3 to 15% by mass of Na 2 O. %, K 2 O is 0.1 to 5% by mass, MgO is 0.1 to 5% by mass, and CaO is 0.1 to 5% by mass.
  • aluminosilicate glass and borosilicate glass are preferable in that they are excellent in impact resistance and vibration resistance.
  • what contains crystallized glass, such as nanocrystallized glass other than said material, for example is preferable.
  • a glass substrate for an information recording medium with higher impact resistance and vibration resistance can be produced.
  • the higher the degree of crystallinity the better the glass substrate for information recording media, such as impact resistance.
  • the higher the degree of crystallinity the more the polishing material other than cerium oxide, such as zirconium oxide (zirconia), is used even when the glass base plate is polished with a polishing liquid containing cerium oxide. There was a tendency that the difference in polishing rate was less likely to occur. In such a case, the effect of the manufacturing method according to the present embodiment can be effectively exhibited. That is, by performing the polishing step in the manufacturing method according to the present embodiment, a sufficiently high quality glass substrate for information recording media can be manufactured while ensuring a high polishing rate.
  • the polishing apparatus used in this polishing step is not particularly limited as long as it is a polishing apparatus used for manufacturing a glass substrate for an information recording medium. Specifically, there is a polishing apparatus 11 as shown in FIG. FIG. 1 is a schematic cross-sectional view showing an example of a polishing apparatus used in a polishing step in the method for manufacturing a glass substrate for information recording medium according to the present embodiment.
  • the apparatus main body 11a includes two surface plates 12 and 13 arranged to face each other.
  • the positional relationship between the respective surface plates is not limited to the upper and lower sides.
  • the surface plate disposed on the upper side is the upper surface plate 12, and the surface plate disposed on the lower side is This is referred to as the lower surface plate 13.
  • the apparatus main body 11a includes a disk-shaped upper surface plate 12 and a disk-shaped lower surface plate 13, and they are arranged at an interval in the vertical direction so that they are parallel to each other. Then, the disk-shaped upper surface plate 12 and the disk-shaped lower surface plate 13 rotate in directions opposite to each other.
  • a plurality of rotatable carriers 14 are provided between the disk-shaped upper surface plate 12 and the disk-shaped lower surface plate 13.
  • the carrier 14 is formed with a plurality of base plate holding holes 51, and the glass base plate 10 can be fitted into the base plate holding holes 51 and disposed.
  • 100 base plate holding holes 51 may be formed, and 100 glass base plates 10 may be fitted and arranged. If it does so, 100 glass base plates can be processed by one process (1 batch).
  • the carrier 14 sandwiched between the surface plates 12 and 13 through the polishing pad 15 is the same as the lower surface plate 13 with respect to the center of rotation of the surface plates 12 and 13 while rotating while holding the glass base plate 10. Revolve in the direction.
  • the disk-shaped upper surface plate 12 and the disk-shaped lower surface plate 13 can be operated by separate driving.
  • the polishing liquid 16 is supplied between the upper surface plate 12 and the glass base plate 10 and between the lower surface plate 13 and the glass base plate 10, respectively.
  • the glass base plate 10 can be polished.
  • the polishing liquid 16 is the above-described polishing liquid.
  • the polishing liquid supply unit 11b includes a liquid storage unit 110 and a liquid recovery unit 120.
  • the liquid reservoir 110 includes a liquid reservoir main body 110a and a liquid supply pipe 110b having a discharge port 110e extending from the liquid reservoir main body 110a to the apparatus main body 11a.
  • the liquid recovery part 120 was extended from the liquid recovery part main body 120a, the liquid recovery pipe 120b extended from the liquid recovery part main body 120a to the apparatus main body 11a, and from the liquid recovery part main body 120a to the polishing liquid supply part 11b.
  • a liquid return pipe 120c was extended from the liquid recovery part main body 120a, the liquid recovery pipe 120b extended from the liquid recovery part main body 120a to the apparatus main body 11a, and from the liquid recovery part main body 120a to the polishing liquid supply part 11b.
  • a liquid return pipe 120c was extended from the liquid recovery part main body 120a, the liquid recovery pipe 120b extended from the liquid recovery part main body 120a to the apparatus main body 11a, and from the liquid recovery part main body 120a
  • the polishing liquid 16 put in the liquid storage unit main body 110a is supplied from the discharge port 110e of the liquid supply pipe 110b to the apparatus main body part 11a, and from the apparatus main body part 11a through the liquid recovery pipe 120b, the liquid recovery part main body 120a.
  • the recovered polishing liquid 16 is returned to the liquid storage part 110 via the liquid return pipe 120c, and can be supplied again to the apparatus main body part 11a.
  • polishing liquid is used in a circulating manner (circulation use)
  • a new polishing liquid is always used without recovering the polishing liquid used for polishing. It may be a case where a polishing liquid is used (flowing use).
  • the reason why the polishing liquid is used by pouring is that, if polishing sludge (polishing waste) generated by polishing is present in the polishing liquid, the surface of the glass substrate may be damaged.
  • the polishing pad used in the polishing step is a processing tool for polishing both main surfaces of the glass substrate, and particularly if it is used in the polishing step when manufacturing the glass substrate for information recording medium, It is not limited.
  • a suede pad etc. are mentioned, for example.
  • the suede pad is a suede type soft foamed resin pad whose surface (polishing layer) is made of a soft foamed resin such as soft foamed polyurethane.
  • the suede pad is a polishing pad in which bubbles are open to the surface (pad surface), and there are relatively many soft walls separating the bubbles.
  • the method for manufacturing the glass substrate for information recording medium according to the present embodiment preferably performs the polishing process according to the present embodiment as a rough polishing process and separately performs a precision polishing process.
  • a precision polishing process is not particularly limited as long as it is a general precision polishing process in the method for producing a glass substrate for information recording medium.
  • the precision polishing step maintains a flat and smooth main surface obtained in the rough polishing step (the polishing step), for example, and a smooth mirror surface having a surface roughness (Rmax) of the main surface of about 0.3 nm or less. This is a mirror polishing process that finishes.
  • This precision polishing step may be performed using, for example, a polishing apparatus similar to that used in the above polishing step. Note that the surface to be polished in the precision polishing step is the main surface, similar to the surface to be polished in the polishing step.
  • an abrasive that generates fewer scratches is used even if the abrasiveness is lower than the abrasive used in the rough polishing process.
  • an abrasive containing silica-based abrasive grains (colloidal silica) having a particle diameter lower than that of the abrasive used in the rough polishing step may be used.
  • the average particle diameter of the silica-based abrasive is preferably about 20 nm.
  • a polishing liquid (slurry liquid) containing the abrasive is supplied to the glass base plate, and the surface of the glass base plate is mirror-polished by sliding the polishing pad and the glass base plate relatively.
  • the slurry liquid may be circulated and used by the polishing liquid supply unit 11b of the polishing apparatus 11, for example.
  • the method for manufacturing a glass substrate for information recording medium may include the polishing step, but may include other steps.
  • a method including a disk machining process, a grinding process (lapping process), an internal / external grinding process, an end surface polishing process, a chemical strengthening process, a polishing process (polishing process), and a cleaning process can be used. And each said process may be performed in this order, and a chemical strengthening process may be performed after a grinding
  • a method including steps other than these may be used.
  • polishing process performs the said grinding
  • the disk processing step is a step of processing the raw glass into a disk-shaped glass base plate 10 in which a through hole 10a is formed in the center so that the inner periphery and the outer periphery are concentric circles as shown in FIG. is there.
  • a glass melting step in which raw glass is melted in a melting furnace to form molten glass
  • a forming step in which the molten glass is formed into a disc-shaped glass base plate, and the formed disc-shaped glass base plate
  • the coring process which forms the through-hole 10a in the center part of this, and is processed into the disk shaped glass base plate 10 as shown in FIG. 2 etc. is provided.
  • FIG. 2 is a top view showing a glass base plate used in the method for manufacturing a glass substrate for information recording medium according to the present embodiment.
  • the glass melting step is not particularly limited as long as raw glass can be melted in a melting furnace to obtain molten glass.
  • the raw glass is not particularly limited, and examples thereof include those exemplified above as the material of the glass base plate that is the object to be polished in the polishing step. Moreover, it does not specifically limit as a melting method of raw material glass, Usually, the method of fuse
  • the forming step is not particularly limited as long as the molten glass can be formed into a disk-shaped glass base plate.
  • the press process etc. which form a disk shaped glass base plate by press molding molten glass are mentioned.
  • the forming step is not limited to the pressing step, and may be a step of, for example, cutting a sheet glass formed by a downdraw method or a float method with a grinding stone to produce a disk-shaped glass base plate.
  • the float method is, for example, a method in which a molten liquid obtained by melting a glass material is poured onto molten tin and solidified as it is.
  • the smoothness is high, for example, the arithmetic average roughness Ra is 0.001 ⁇ m.
  • the following mirror surface is provided.
  • a thickness of a glass base plate a 0.95 mm thing is mentioned, for example.
  • the surface roughness of a glass base plate or a glass substrate for example, Ra or Rmax, can be measured using a general surface roughness measuring machine.
  • the coring process is a process of performing a coring process in which a through hole 10a is formed at the center of the disk-shaped glass base plate formed in the forming process.
  • the disk-shaped glass base plate 10 in which the through-hole 10a was formed in the center part as shown in FIG. 2 is obtained.
  • the coring process is not particularly limited as long as it is a drilling process that forms a through hole in the center of the glass base plate.
  • a method of forming a through-hole in the center of the glass base plate by grinding with a core drill having a diamond grindstone or the like in the cutter portion, a cylindrical diamond drill, or the like can be used. By doing so, a through hole is formed in the center of the glass base plate, and an annular glass base plate is obtained in plan view.
  • the grinding apparatus used in the grinding process is not particularly limited as long as it can be used as a grinding apparatus used in the grinding process in the method of manufacturing the glass substrate for information recording medium. Specifically, it is the same as the polishing apparatus used in the polishing step, and includes a resin sheet (grinding sheet) using diamond as a fixed abrasive instead of the polishing pad.
  • examples of the first lapping step include a step in which the entire surface of the glass base plate has a substantially uniform surface roughness.
  • the grinding sheet used in the first lapping step for example, it is preferable to use one having an average particle diameter of 6 to 12 ⁇ m of fixed abrasive grains.
  • the difference between the minimum value and the maximum value of Ra obtained is about 0.01 to 0.4 ⁇ m. It is preferable to do.
  • examples of the second lapping step include a step in which a glass base plate from which defects such as large undulations, chips and cracks are removed can be obtained.
  • the grinding sheet used in the second lapping step for example, it is preferable to use a fixed abrasive having an average particle diameter of 0.5 to 4 ⁇ m, and preferably 1 to 2 ⁇ m.
  • Rmax of the obtained glass base plate is preferably set to 0.5 to 2 ⁇ m.
  • Ra is preferably 0.1 to 0.5 ⁇ m. If the surface of the glass base plate after the second lapping step is too rough, it is difficult to obtain a glass substrate having sufficiently high smoothness even if the polishing step is performed.
  • the glass base plate after the second lapping step is preferably as smooth as possible, that is, as Ra is small, but in the lapping step, about 0.01 ⁇ m is the limit, and 0.01 ⁇ m is the limit. This is considered to be the lower limit value of the arithmetic average roughness Ra of the glass base plate after the second lapping step.
  • the inner / outer grinding step is a step of grinding the outer peripheral end surface and the inner peripheral end surface of the glass base plate. Specifically, the process etc. which grind the outer peripheral end surface and inner peripheral end surface of a glass base plate with grinding wheels, such as a drum-shaped diamond grindstone, are mentioned.
  • the end surface polishing step is a step of polishing the outer peripheral end surface and the inner peripheral end surface of the glass base plate. Specifically, a plurality of glass base plates subjected to the inner and outer grinding steps, for example, about 100, are stacked and laminated, and in this state, the outer peripheral end surface and the inner peripheral end surface are polished using an end surface polishing machine. And the like.
  • the chemical strengthening step is not particularly limited, and specific examples include a step of immersing a glass base plate in a chemical strengthening solution (strengthening treatment solution) to form a chemical strengthening layer on the glass base plate.
  • a chemical strengthening layer can be formed in the surface of a glass base plate, for example, a 5 micrometer area
  • a chemical strengthening layer impact resistance, vibration resistance, heat resistance, etc. can be improved.
  • alkali metal ions such as lithium ions and sodium ions contained in the glass base plate are potassium having a larger ion radius. It is carried out by an ion exchange method for substituting alkali metal ions such as ions. Due to the strain caused by the difference in ion radius, compressive stress is generated in the ion-exchanged region, and the surface of the glass base plate is strengthened. That is, it is considered that the reinforcing layer is suitably formed on the glass base plate by this chemical strengthening step.
  • the chemical strengthening treatment solution is not particularly limited as long as it is a chemical strengthening treatment solution used in the chemical strengthening step in the method for producing a glass substrate for a magnetic information recording medium.
  • a melt containing potassium ions a melt containing potassium ions and sodium ions, and the like can be given.
  • melts obtained by melting potassium nitrate, sodium nitrate, potassium carbonate, sodium carbonate, and the like examples include melts obtained by melting potassium nitrate, sodium nitrate, potassium carbonate, sodium carbonate, and the like.
  • a melt obtained by melting potassium nitrate and a melt obtained by melting sodium nitrate are preferably mixed in approximately the same amount.
  • the glass base plate or the glass substrate before the cleaning step such as the final cleaning step is kept in contact with the liquid in order to prevent foreign matter from adhering to the surface. It is preferable.
  • the glass substrate is dried.
  • drying method include drying with IPA vapor, spin drying, and hot water drying.
  • FIG. 3 is a partial cross-sectional perspective view showing a magnetic disk as an example of a magnetic recording medium using the glass substrate for information recording medium manufactured by the method for manufacturing the glass substrate for information recording medium according to the present embodiment.
  • This magnetic disk D includes a magnetic film 102 formed on the main surface of a circular glass substrate 101 for an information recording medium. For the formation of the magnetic film 102, a known method is used.
  • a formation method for forming the magnetic film 102 by spin-coating a thermosetting resin in which magnetic particles are dispersed on the glass substrate 101 for information recording medium
  • examples thereof include a forming method for forming the magnetic film 102 by sputtering (sputtering method) and a forming method for forming the magnetic film 102 on the glass substrate 101 for information recording medium by electroless plating (electroless plating method).
  • the thickness of the magnetic film 102 is about 0.3 to 1.2 ⁇ m in the case of the spin coating method, and about 0.04 to 0.08 ⁇ m in the case of the sputtering method, and is based on the electroless plating method. In some cases, the thickness is about 0.05 to 0.1 ⁇ m. From the viewpoint of thinning and densification, film formation by sputtering is preferable, and film formation by electroless plating is preferable.
  • the magnetic film 102 has a multilayer structure (for example, CoPtCr / CrMo / CoPtCr, CoCrPtTa / CrMo / CoCrPtTa, etc.) divided by a nonmagnetic film (for example, Cr, CrMo, CrV, etc.) in order to reduce noise.
  • a multilayer structure for example, CoPtCr / CrMo / CoPtCr, CoCrPtTa / CrMo / CoCrPtTa, etc.
  • ferrite or iron - may be a rare earth, also, Fe in a non-magnetic film made of SiO 2, BN, etc., Co, FeCo, CoNiPt and the like
  • a granular material having a structure in which the magnetic particles are dispersed may be used.
  • either an inner surface type or a vertical type recording format may be used for recording on the magnetic film 102.
  • the surface of the magnetic film 102 may be thinly coated with a lubricant.
  • a lubricant include those obtained by diluting perfluoropolyether (PFPE), which is a liquid lubricant, with a freon-based solvent.
  • an underlayer or a protective layer may be provided on the magnetic film 102 as necessary.
  • the underlayer in the magnetic disk D is appropriately selected according to the magnetic film 102.
  • the material for the underlayer include at least one material selected from nonmagnetic metals such as Cr, Mo, Ta, Ti, W, V, B, Al, and Ni.
  • the material of the underlayer is preferably Cr alone or a Cr alloy from the viewpoint of improving magnetic characteristics.
  • the underlayer is not limited to a single layer, and may have a multilayer structure in which the same or different layers are stacked.
  • Examples of such an underlayer having a multilayer structure include multilayer underlayers such as Cr / Cr, Cr / CrMo, Cr / CrV, NiAl / Cr, NiAl / CrMo, and NiAl / CrV.
  • Examples of the protective layer that prevents wear and corrosion of the magnetic film 102 include a Cr layer, a Cr alloy layer, a carbon layer, a hydrogenated carbon layer, a zirconia layer, and a silica layer. These protective layers can be continuously formed with the underlayer and the magnetic film 102 by an in-line sputtering apparatus. These protective layers may be a single layer, or may be a multi-layer structure composed of the same or different layers.
  • a SiO 2 layer may be formed on the Cr layer.
  • Such a SiO 2 layer is formed by dispersing and applying colloidal silica fine particles in a tetraalkoxysilane diluted with an alcohol-based solvent on the Cr layer and further baking.
  • the information recording medium glass substrate 101 is formed with the above-described composition. Can be done by sex.
  • the glass substrate 101 for information recording media in this embodiment was used for a magnetic recording medium (magnetic disk) was demonstrated above, it is not limited to this, for information recording media in this embodiment
  • the glass substrate 101 can also be used for magneto-optical disks, optical disks, and the like.
  • One aspect of the present invention includes a polishing step of polishing the surface of the glass base plate by relatively moving the glass base plate and the polishing pad in a state where the polishing liquid is supplied onto the glass base plate.
  • the polishing liquid contains a mechanical abrasive and a cellulose-based additive, the average particle diameter of the mechanical abrasive is 0.5 to 1.5 ⁇ m, and the weight-average molecular weight of the cellulose-based additive is The method for producing a glass substrate for an information recording medium, characterized in that it is 20000-75000.
  • a sufficiently high quality glass substrate for an information recording medium can be produced while ensuring a high polishing rate without using cerium oxide as an abrasive.
  • the method for manufacturing the glass substrate for information recording medium preferably includes a precision polishing step for precisely polishing the surface of the glass base plate polished in the polishing step.
  • a sufficiently high-quality glass base plate can be obtained as the glass base plate after the rough polishing step in the polishing step, so that the glass base plate is further precisely polished.
  • a sufficiently high quality glass substrate for information recording media can be obtained.
  • a weight average molecular weight of the cellulose-based additive is 25000 to 50000.
  • a sufficiently high quality glass substrate for information recording media can be produced at a higher polishing rate.
  • the cellulose-based additive is at least one selected from the group consisting of methylcellulose, hydroxypropylmethylcellulose, and carboxymethylcellulose.
  • a sufficiently high quality glass substrate for information recording media can be produced at a higher polishing rate.
  • the mechanical abrasive is at least one of zirconium oxide and aluminum oxide.
  • a sufficiently high quality glass substrate for information recording media can be produced at a higher polishing rate.
  • the polishing pad is a suede pad.
  • a glass substrate for information recording medium with higher quality can be manufactured.
  • both main surfaces of the obtained glass base plate were ground using a double-side grinding machine.
  • the coring process was given to the glass base plate which gave the grinding process, and the through-hole was formed in the center part of the glass base plate.
  • a circular center hole (through hole) having a diameter of about 19.6 mm was formed in the center of the ground glass plate using a core drill equipped with a cylindrical diamond grindstone.
  • an inner and outer grinding step was performed on the glass base plate. Specifically, the outer peripheral end face and the inner peripheral end face of the glass base plate were ground using a drum-shaped diamond grindstone so that the outer diameter of the glass base plate was 65 mm and the inner diameter was 20 mm. Then, the end surface process was performed with respect to the glass base plate. Specifically, with 100 glass base plates stacked, the outer peripheral end surface and the inner peripheral end surface of the glass base plate were polished using an end surface polishing machine. Nylon fiber having a diameter of 0.2 mm was used as the brush hair of the polishing machine. As the polishing liquid, a slurry containing cerium oxide having an average primary particle diameter of 3 ⁇ m as abrasive grains was used. Thereafter, both surfaces of the glass base plate were processed using a diamond sheet with a double-side grinding machine.
  • the glass base plate thus obtained was subjected to a polishing process. Specifically, both main surfaces of the glass base plate were polished using a polishing apparatus as shown in FIG. At that time, a suede pad (NP178 manufactured by Filwel: Asker C hardness 82) was used as a polishing pad.
  • a polishing liquid a polishing liquid having the composition shown in Table 1, specifically, 10% by mass of zirconium oxide (zircon) having an average particle diameter (D50) of 0.8 ⁇ m, and 0.3 cellulose as an additive, methylcellulose (MC) 0.3 A polishing solution containing water in mass and the balance being water was used.
  • a final cleaning process was performed on the glass substrate that had been subjected to the precision polishing process. Specifically, scrub cleaning was first performed. At that time, a liquid obtained by adding a nonionic surfactant to increase the cleaning ability was used as the cleaning liquid. Thereafter, in order to remove the cleaning liquid remaining on the surface of the lath substrate, a water rinse cleaning process was performed in an ultrasonic bath for 2 minutes, and an IPA cleaning process was performed in an ultrasonic bath for 2 minutes. Finally, the surface was dried with IPA vapor. By doing so, a glass substrate was obtained.
  • Example 1 is the same as Example 1 except that the polishing liquid having the composition shown in Table 1 is used as the polishing liquid in the polishing step.
  • the copolymer represents an acrylic acid-maleic acid copolymer.
  • polishing speed First, the polishing rate in the polishing step of Comparative Example 1 was measured. Next, the polishing rate in the polishing process of each Example and Comparative Example was measured. And the ratio of the polishing rate in each Example and a comparative example with respect to the polishing rate in the comparative example 1 was computed. That is, if the polishing rate in each Example and Comparative Example is higher than the polishing rate in Comparative Example 1, the ratio is greater than 1. This case was evaluated as “ ⁇ ”. If the polishing rate in each example and comparative example is lower than the polishing rate in comparative example 1, the ratio becomes smaller than 1. If this ratio was 1 or less, it was evaluated as “ ⁇ ”.
  • an atomic force microscope was used to measure a range of 10 ⁇ m ⁇ 10 ⁇ m, and the surface roughness Ra was calculated from the obtained results.
  • the obtained Ra is 3 mm or less, it is evaluated as “ ⁇ ”, when it exceeds 3 mm and is 4 mm or less, it is evaluated as “ ⁇ ”, and when it is more than 4 mm and 5 mm or less, it is evaluated as “ ⁇ ”.
  • it exceeded 5cm it evaluated as "x”.
  • it evaluated as "x” by the following flaw evaluation since the subsequent precision grinding
  • the glass base plate after the polishing step was measured using a fine defect visualization inspection apparatus (Micro-Max manufactured by Vision Cytec Co., Ltd.). As a result, if no flaws can be confirmed, evaluate as “ ⁇ ”, if one flaw can be confirmed, evaluate as “ ⁇ ”, and if two to four flaws can be confirmed, evaluate as “ ⁇ ”. When 5 or more flaws could be confirmed, it was evaluated as “ ⁇ ”.
  • a glass substrate for an information recording medium capable of producing a sufficiently high quality glass substrate for an information recording medium while ensuring a high polishing rate without using cerium oxide as an abrasive.
  • a manufacturing method is provided.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing Of Magnetic Record Carriers (AREA)

Abstract

Un aspect de la présente invention porte sur un procédé pour la production d'un substrat en verre pour un support d'enregistrement d'informations, qui est caractérisé en ce qu'il comprend une étape de polissage qui, alors que du fluide de polissage est apporté sur une ébauche en verre, déplace l'ébauche en verre et un tampon de polissage l'un par rapport à l'autre et polit la surface de l'ébauche en verre et qui est caractérisé en ce que le fluide de polissage comprend un agent de polissage mécanique et un additif à base de cellulose, la taille moyenne des particules de l'agent de polissage mécanique étant de 0,5 à 1,5 µm et la masse moléculaire moyenne en poids de l'additif à base de cellulose étant de 20 000 à 75 000.
PCT/JP2013/007549 2012-12-26 2013-12-24 Procédé pour la production de substrat en verre pour support d'enregistrement d'informations WO2014103284A1 (fr)

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JP2012282884 2012-12-26

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003510446A (ja) * 1999-09-30 2003-03-18 昭和電工株式会社 研磨用組成物および研磨方法
JP2005014204A (ja) * 2003-05-15 2005-01-20 Showa Denko Kk 研磨用組成物および研磨方法
JP2005023313A (ja) * 2003-06-13 2005-01-27 Showa Denko Kk 研磨用組成物および研磨方法
JP2005034986A (ja) * 2003-06-27 2005-02-10 Showa Denko Kk 研磨用組成物とそれを用いた基板研磨方法
JP2012079964A (ja) * 2010-10-04 2012-04-19 Nissan Chem Ind Ltd 半導体ウェーハ用研磨液組成物
WO2012083115A2 (fr) * 2010-12-17 2012-06-21 Cabot Microelectronics Corporation Composition et procédé utilisés pour le polissage de polysilicium

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003510446A (ja) * 1999-09-30 2003-03-18 昭和電工株式会社 研磨用組成物および研磨方法
JP2005014204A (ja) * 2003-05-15 2005-01-20 Showa Denko Kk 研磨用組成物および研磨方法
JP2005023313A (ja) * 2003-06-13 2005-01-27 Showa Denko Kk 研磨用組成物および研磨方法
JP2005034986A (ja) * 2003-06-27 2005-02-10 Showa Denko Kk 研磨用組成物とそれを用いた基板研磨方法
JP2012079964A (ja) * 2010-10-04 2012-04-19 Nissan Chem Ind Ltd 半導体ウェーハ用研磨液組成物
WO2012083115A2 (fr) * 2010-12-17 2012-06-21 Cabot Microelectronics Corporation Composition et procédé utilisés pour le polissage de polysilicium

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