WO2008035586A1 - Procédé de production d'un substrat de verre pour un disque magnétique et procédé de fabrication d'un disque magnétique - Google Patents

Procédé de production d'un substrat de verre pour un disque magnétique et procédé de fabrication d'un disque magnétique Download PDF

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Publication number
WO2008035586A1
WO2008035586A1 PCT/JP2007/067619 JP2007067619W WO2008035586A1 WO 2008035586 A1 WO2008035586 A1 WO 2008035586A1 JP 2007067619 W JP2007067619 W JP 2007067619W WO 2008035586 A1 WO2008035586 A1 WO 2008035586A1
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WO
WIPO (PCT)
Prior art keywords
glass substrate
polishing
shape
magnetic disk
main surface
Prior art date
Application number
PCT/JP2007/067619
Other languages
English (en)
Japanese (ja)
Inventor
Masahiro Katagiri
Kotaro Yoshimaru
Original Assignee
Hoya Corporation
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 Hoya Corporation filed Critical Hoya Corporation
Priority to CN2007800012384A priority Critical patent/CN101356040B/zh
Publication of WO2008035586A1 publication Critical patent/WO2008035586A1/fr

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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

Definitions

  • the present invention relates to a method for manufacturing a glass substrate for a magnetic disk used as a recording medium for a computer or the like, and a method for manufacturing a magnetic disk.
  • magnetic recording media have been required to further improve recording density.
  • Patent Document 1 has been proposed as a method for manufacturing a glass substrate for a magnetic disk that prevents edge shape disturbance and the like.
  • Patent Document 1 Japanese Unexamined Patent Publication No. 2005-141852
  • the flying height of the recording head is further increased from the conventional flying height of, for example, about 10 nm, the flying height of the magnetic head is not stable, and the recording head crashes. There was a problem.
  • the cause of the crash is that the end shape of the glass substrate is not the desired flat shape.
  • the method for manufacturing a glass substrate for a magnetic disk includes a plurality of processing steps for changing the shape of the end portion of the glass substrate, including a plurality of polishing steps. Reviewing only one of these multiple processing steps to form the desired end shape is another requirement that must be met (for example, manufacturing conditions such as processing time and processing conditions, cost, glass substrate There is a limit in relation to the characteristic value of the surface shape obtained as
  • the present invention is to provide a glass substrate for a magnetic disk having a desired end shape by reviewing a plurality of processing steps including a plurality of polishing steps. To do.
  • the inventor of the present application has obtained the shape of the end shape in the preceding polishing step in order to obtain the end shape to be finally obtained. Reduce the flying height of the magnetic head by grasping the change characteristics (shape change amount and change shape) before the preceding polishing process and setting the shape change characteristics of the end shape in the subsequent polishing process. As a result, the inventors have found that an end shape capable of achieving the above can be obtained, and have completed the present invention.
  • what is grasped in advance before the preceding polishing step may be a change in the end shape in the subsequent polishing step. In that case, the shape change characteristic of the end shape in the preceding polishing process may be set in accordance with the grasped change.
  • the gas after the first processing step is before the first processing step.
  • the end shape is obtained by changing the glass substrate in a direction that cancels the end shape grasped by the grasping step.
  • the desired shape described above may be that the end shape of the glass substrate is substantially flat, or may be a shape in which the end shape of the glass substrate is lowered as compared with the central portion. .
  • the second treatment step is finished. It is preferable that the end shape of the glass substrate is lowered as compared with the central portion at the time when the strength S is reached.
  • the end shape of the glass substrate is substantially flat when the second processing step is finished. It is preferable to make it a shape.
  • a polishing liquid containing abrasive grains is supplied between the glass substrate and a polishing pad for polishing the main surface of the glass substrate, and the glass substrate is moved by moving the glass substrate and the polishing pad relatively.
  • the shape of the end of the main surface of the glass substrate is lower than the central portion of the main surface in the plurality of polishing steps.
  • the shape of the end portion is changed by offsetting the shape of the preceding polishing step for polishing so as to obtain the shape and the shape of the glass substrate raised or lowered in the preceding polishing step) And a subsequent polishing step of performing polishing to obtain a desired shape.
  • a method for manufacturing a glass substrate for a magnetic disk comprising:
  • the preceding polishing step when the polishing is performed so that the end shape of the main surface of the glass substrate has a raised shape, the preceding polishing step.
  • a polishing pad having a hardness higher than that of the polishing pad used in the above is used in the subsequent polishing step, and polishing is performed so that the shape of the end of the main surface of the glass substrate is lowered in the preceding polishing step, the preceding pad is used.
  • a polishing pad having a lower hardness than the polishing pad used in the polishing process is used in the subsequent polishing process.
  • the subsequent polishing step is performed so that the roughness (Ra) of the main surface of the glass substrate after the subsequent polishing step is 0.2 nm or less.
  • a method for producing a magnetic disk comprising forming at least a magnetic layer on a surface of a glass substrate obtained by the above method for producing a glass substrate for a magnetic disk.
  • a polishing liquid containing abrasive grains is supplied between a glass substrate and a polishing pad for polishing the main surface of the glass substrate, and the glass substrate and the polishing pad are moved relative to each other to move the glass substrate.
  • the method for manufacturing a glass substrate for a magnetic disk including a polishing step for polishing a main surface
  • the polishing step when a glass substrate having a flat end on the main surface is polished, the shape of the end compared to the central portion.
  • performing a second polishing step of polishing the main surface of the glass substrate so that the glass substrate has a lowered or raised shape, thereby making the end shape of the glass substrate substantially flat.
  • Abrasive grains are included between the glass substrate and the polishing pad for polishing the main surface of the glass substrate.
  • the polishing step has a shape in which, when a glass substrate having a flat end portion on the main surface is polished, the shape of the end portion is higher than that of the central portion.
  • Descent A second polishing step of polishing the main surface of the glass substrate so as to have a raised shape, and the end shape of the glass substrate is changed by performing the polishing step and the chemical strengthening treatment step.
  • the roughness (Ra) of the main surface of the glass substrate after the second polishing step is 0.2 nm or less. It is desirable to polish it like this.
  • a method for producing a magnetic disk comprising forming at least a magnetic layer on a surface of a glass substrate obtained by the method for producing a glass substrate for a magnetic disk according to the seventh and eighth aspects.
  • the polishing apparatus used in the present invention includes a plurality of sets each including a set of polishing abrasive grains contained in the polishing liquid and a polishing pad that moves relative to the glass substrate while being supplied with the polishing liquid.
  • the plurality of sets have a shape in which the end of the main surface is raised (or lowered) compared to the central portion.
  • the end portion of the main surface is substantially flattened.
  • the shape of the end portion of the main surface may be lower than the center portion as a result of the subsequent polishing step.
  • the hardness of the second set of polishing pads may be higher than the first set of polishing pads described above, or the hardness of the second set of polishing pads may be lower than the first set of polishing pads.
  • the end shape obtained in the subsequent polishing step can be made substantially flat, and the lowered shape can remain.
  • This lowered shape is left in advance so as to offset the raised shape generated in the chemical strengthening process performed further after the subsequent polishing process.
  • the end of the glass substrate is left behind. Can be finally formed into a substantially flat shape.
  • FIG. 1 is a diagram for explaining a double-side polishing apparatus as an embodiment of a polishing apparatus for a magnetic disk glass substrate according to the present invention.
  • FIG. 2 is an enlarged cross-sectional view illustrating a configuration of a polishing pad used in the present invention.
  • FIG. 3 is a schematic diagram for explaining a method of manufacturing a magnetic disk glass substrate according to the first embodiment of the present invention using the polishing apparatus shown in FIG. 1.
  • FIG. 4 is a cross-sectional view of the glass substrate cut along a plane that passes through the center of the disk-shaped glass substrate and is perpendicular to the main surface.
  • FIG. 5 (a) is a diagram showing polishing conditions in the first example of the present invention, and (b) is a diagram showing polishing conditions in a comparative example compared with the first example.
  • FIG. 6 is a schematic view for explaining a method for manufacturing a magnetic disk glass substrate according to a second embodiment of the present invention using the polishing apparatus shown in FIG. 1.
  • FIG. 6 is a schematic view for explaining a method for manufacturing a magnetic disk glass substrate according to a second embodiment of the present invention using the polishing apparatus shown in FIG. 1.
  • FIG. 7 (a) is a diagram showing polishing conditions in a second example of the present invention, and (b) is a diagram showing polishing conditions in a comparative example compared with the second example.
  • ski jump refers to the shape of the edge of the main surface of the glass substrate that is raised (swelled) compared to the center.
  • roll-off indicates a shape that is lowered (lowered) at the end of the main surface of the glass substrate as compared with the central portion.
  • flat indicates a shape (shape in a direction perpendicular to the main surface) in which the end of the main surface of the glass substrate is substantially the same as the central portion. This will be described in detail below.
  • FIG. 4 is a cross-sectional view of the glass substrate 1 cut along a plane that passes through the center of the disk-shaped glass substrate 1 and is perpendicular to the main surface la, and FIG. 4 (a) shows ski jumping.
  • (b) indicates roll-off.
  • two reference points Rl and R2 are set in order from the center.
  • a boundary line R3 outer edge position of the gliding area G perpendicular to the main surface la with a certain distance margin in the outer peripheral direction from the outer peripheral edge of the recording area M is set.
  • the intersection of the glass substrate 1 and the contour line of the glass substrate 1 is defined as the roll-off point R.
  • points Rl, R2, and R3 are set in the radial direction from the center of the glass substrate 1.
  • the points R1 and R2 are set at the center of the glass substrate 1 (position near the center in the radial direction of the glass substrate 1).
  • a straight line R4 passing through the points R1 and R2 is drawn, a deviation between the straight line R4 and the surface of the glass substrate 1 between the points R2 and R3 (a deviation in a direction perpendicular to the substrate surface) is measured.
  • the point with the largest divergence in the positive direction is the ski jump point (point S), and the magnitude of the divergence at that time is the ski jump value, while the negative direction ( The point with the greatest divergence
  • the roll-off value is the nore-off point (point R) and the magnitude of the deviation at that time.
  • ski jump value S5 is positive and the roll-off value R5 is negative.
  • ski jump value S5 is zero and the roll-off value R5 is negative.
  • the shape in which the ski jump value S5 is positive as shown in Fig. 4 (a) is called a ski jump (the shape in which the end of the main surface la is raised compared to the central portion), as shown in Fig. 4 (b).
  • the shape in which the ski jump value is zero and the roll-off straight R5 is negative is called roll-off (the shape in which the end of the main surface la is lowered compared to the center).
  • roll-off the shape in which the end of the main surface la is lowered compared to the center.
  • the points Rl, R2 and the boundary spring R3 are appropriately selected according to the size of the glass substrate 1.
  • the boundary line R3 is set at a position of lmm inward from the end surface of the glass substrate 1.
  • the distance from the center of the substrate is 23 mm to point R1, 27 mm to point R2, and 31 to boundary R3. It can be set to 5mm, 32.5mm to the end face.
  • the position of 71% to the outer diameter (end face) of the substrate can be set as the point Rl
  • the position of 83% can be set as the point R2
  • the position of 97% can be set as the point R3. it can.
  • ski jump value and roll-off value are each in the range of ⁇ 0.10 in, and more preferably in the range of ⁇ 0.0511.
  • ski jumping or roll-off occurs depends on various factors. For example, it depends on the grain size of the abrasive grains contained in the polishing liquid, the hardness of the polishing pad, the polishing conditions, and the like. It is determined.
  • the edge shape on the main surface of the glass substrate is of course important. Roughness is also important.
  • the magnetic head floats from the inner peripheral edge to the outer peripheral edge of the main surface. Therefore, the roughness at each position, and particularly the roughness at the edge of the main surface of the glass substrate where the rotation speed is high, are important.
  • the main surface of the glass substrate preferably has a surface roughness Ra of 0.2 nm or less as measured by an AFM (atomic force microscope).
  • Rmax is preferably 2 nm or less.
  • the shape wavelength is 16 111 to 1; It is more preferable that when the surface shape of a band of 9 m is extracted and the root mean square roughness Rq (RMS) of this surface shape is defined as the minute undulation Rq, the minute undulation Rq is 0.5 nm or less.
  • FIG. 1 is a view for explaining a double-side polishing apparatus as a first embodiment of a polishing apparatus for a magnetic disk glass substrate according to the present invention.
  • the double-side polishing apparatus 3 is an apparatus that uses a polishing pad 10 and performs polishing by relatively moving the glass substrate 1 and the polishing pad 10.
  • FIG. 1 (a) is an explanatory view of a drive mechanism unit of a double-side polishing apparatus
  • FIG. 1 (b) is a cross-sectional view of the main part of a double-side polishing apparatus having upper and lower surface plates.
  • the double-side polishing apparatus 3 includes a polishing carrier mounting portion having an internal gear 34 and a sun gear 35 that are driven to rotate at a predetermined rotation ratio, and the polishing carrier mounting. And an upper surface plate 31 and a lower surface plate 32 that are driven in reverse rotation with respect to each other.
  • a polishing pad 10 to be described later is attached to the surfaces of the upper surface plate 31 and the lower surface plate 32 facing the glass substrate 1.
  • a plurality of polishing carriers 33 mounted so as to mesh with the internal gear 34 and the sun gear 35 revolve around the sun gear 35 while rotating around the sun gear 35.
  • a plurality of glass substrates 1 are held on the plurality of polishing carriers 33, respectively.
  • the upper surface plate 31 is movable in the vertical direction, and as shown in FIG. Press the polishing pad 10 against the main surface. Then, while supplying the slurry containing abrasive grains, the planetary gear motion of the polishing carrier 33 and the upper surface plate 31 and the lower surface plate 32 rotate reversely to each other, so that the glass substrate 1 and the polishing pad 10 are The main surfaces of the front and back surfaces of the glass substrate 1 are polished relative to each other.
  • the double-side polishing apparatus 3 configured as described above includes a set including polishing abrasive grains contained in the polishing liquid and a polishing pad 10 that moves relative to the glass substrate 1 while being supplied with the polishing liquid. By using a plurality of sets, it can be used for polishing the main surface of the glass substrate 1 that is performed a plurality of times stepwise in the glass substrate manufacturing process. In the examples described later, as the process of polishing the main surface of the glass substrate 1, the polishing process is performed twice: a preliminary polishing (primary polishing) process and a mirror polishing (secondary polishing) process. The structure of the double-side polishing apparatus 3 is almost the same in these polishing processes.
  • the composition of the polishing abrasive grains contained in the polishing liquid (slurry) used and the polishing pad 10 are different. As a general tendency, the later the subsequent process, the smaller the abrasive grain size, and the hardness of the polishing pad 10 becomes softer.
  • a pad that is softer than the conventional technique is used as a primary polishing (preliminary polishing) pad. May be available. For this reason, the primary polishing may be able to achieve its objectives with less machining allowance than the conventional technology.
  • the substrate edge bulge (ski jump) may occur more significantly. In such a case, in the secondary polishing, the ski jump generated in the primary polishing may not be offset, and the substrate edge may become a ski jump shape.
  • the size of the abrasive grains and the polishing pad material 'hardness are changed.
  • the ski jump generated in the primary polishing is changed in a direction that cancels out in the secondary polishing, so that the edge shape of the substrate approaches flat.
  • FIG. 2 is an enlarged cross-sectional view illustrating the configuration of the polishing pad used in the present invention.
  • the polishing pad 10 is made of a synthetic resin foam such as polyurethane or polyester. In particular, polyurethane foam is preferred at present.
  • the polishing pad 10 is not It consists of a base layer 13 made of woven fabric or the like, and a nap layer 14 laminated on the surface of the base layer 13.
  • a plurality of bubbles are formed in a zero shape in the thickness direction of the nap layer 14. In the present embodiment, this bubble is the nap hole 15.
  • the hardness of such a foam can be adjusted by the amount of air bubbles (nap holes 15) mixed therein.
  • FIG. 3 is a schematic view showing an embodiment of a method for producing a glass substrate for a magnetic disk according to the present invention using the polishing apparatus shown in FIG.
  • This method includes a plurality of polishing steps shown in FIGS. 3 (a) and 3 (b).
  • the main surface of the glass substrate 1 is polished by relatively moving the glass substrate 1 and the polishing pad 10 or 20 while supplying a polishing liquid containing the abrasive grains 40 or 50.
  • FIG. 3 (a) shows a pre-polishing step in which the end of the main surface is polished so as to have a raised shape (ski jump) compared to the central portion, and corresponds to the pre-polishing step in the examples described later.
  • FIG. 3 shows a pre-polishing step in which the end of the main surface is polished so as to have a raised shape (ski jump) compared to the central portion, and corresponds to the pre-polishing step in the examples described later.
  • FIG. 3 (b) shows a subsequent polishing process in which the raised shape (ski jump) is changed in a direction to cancel and the end portion is made to approach a flat surface, and corresponds to a mirror polishing process in an example described later.
  • the preceding polishing process is realized by a set including the polishing abrasive grains 40 and the polishing pad 10
  • the subsequent polishing process is realized by a set including the polishing abrasive grains 50 and the polishing pad 20.
  • the "central portion” means an area including the center in the radial direction in an information recording area in which information is written when a magnetic disk is manufactured using a magnetic disk glass substrate, This corresponds to at least a part of the glide region G shown in FIG.
  • FIG. 3 (b) A grasping step of determining the hardness of the polishing pad 20 and the particle size of the abrasive grains 50 used in the subsequent polishing step may be further included.
  • the processing conditions in the subsequent polishing process can be determined! /.
  • the hardness of the polishing pad 20 used in the subsequent polishing step of FIG. 3 (b) may be made higher than that of the polishing pad 10 used in the preceding polishing step of FIG. 3 (a).
  • the hardness of the polishing pads 10 and 20 may be adjusted by the amount of bubbles mixed in these pads.
  • the abrasive grains used in the preceding polishing process of FIG. You may make the particle size of the abrasive grain used for a subsequent grinding
  • the present invention includes a grasping step for grasping in advance the shape of the edge of the glass substrate obtained by the preceding polishing step, a determining step for determining the hardness of the polishing pad and the abrasive grain size used in the subsequent polishing step, including.
  • the glass having a flat end is temporarily assumed.
  • the glass substrate 100 is polished so that the end portion is lower than the center portion (roll-off).
  • the end portion of the main surface can be made substantially flat as shown in FIG. 3 (c). Is possible.
  • the end of the main surface may be lowered (rolled off) from the center.
  • This is a polishing method in which an end shape change (ski jump) that occurs in a chemical strengthening process performed further after the subsequent polishing process is anticipated in advance and roll-off is performed in the subsequent polishing process. Even if it says roll-off, it means that the roll-off is closer to flat than the ski jump caused by the preliminary polishing process.
  • the preceding polishing step primary polishing step and preliminary polishing step
  • the subsequent polishing step secondary polishing step and mirror polishing step
  • the end shape of the glass substrate is created so that the end shape of the glass substrate after the subsequent polishing step described later is flattened. Specifically, in the preceding polishing step, when a glass substrate having a flat end on the main surface is polished, the main surface of the glass substrate is formed so that the shape of the end is raised compared to the center. Grind.
  • the end shape of the glass substrate is flattened. Specifically, in the subsequent polishing step, when a glass substrate having a flat end on the main surface is polished, the shape of the end becomes a lower shape than the central portion. To polish.
  • the surface of the glass substrate is mirror-finished.
  • colloidal silica particles are preferably used.
  • the content of colloidal silica particles in the polishing liquid is preferably 5% by weight or more and 40% by weight or less.
  • the grain diameter of the colloidal silica particles is preferably 80 nm or less, more preferably 50 nm or less, more preferably the force S. This is because such fine abrasive grains can provide a smooth mirror surface preferable as a glass substrate for a magnetic disk.
  • the lower limit of the grain diameter is preferably determined in consideration of the polishing rate in the subsequent polishing step, for example, 20 nm or more.
  • the surface roughness of the glass substrate 10 is polished so that, for example, the arithmetic average roughness (Ra) is 0.2 nm or less and the maximum peak height (Rp) is 2 nm or less.
  • the maximum peak height (Rp) means the surface shape of a predetermined region of the surface of the glass substrate, the average surface of this surface shape is obtained, and the average of the highest point when this average surface is used as a reference. It is the height from the surface. These values are measured using AFM (Atomic Force Microscope).
  • a magnetic disk is manufactured by forming at least a magnetic layer on the surface of the glass substrate obtained by the method for manufacturing a glass substrate for a magnetic disk described above, a desired end such as a magnetic disk having a substantially flat end is obtained. A magnetic disk having a part shape is obtained.
  • the glass substrate 1 is changed in a direction in which the first processing step performed on the glass substrate 1 and the change in the end shape of the glass substrate 1 generated in the first processing step are canceled
  • An embodiment including a second processing step of forming a desired end shape is also conceivable.
  • the first and second processing steps for changing the shape of the end portion of the glass substrate 1 in a direction to cancel each other are not limited to a plurality of polishing steps. That is, any embodiment corresponding to the technical idea of changing the shape of the end portion in the subsequent process in a direction that cancels out the change in the end portion shape can be considered.
  • the end shape changes. Therefore, before the first processing step, the change in the end shape that occurs in the step is grasped in advance. 2 treatment
  • the treatment conditions of the process may be determined.
  • the end shape of the glass substrate may be measured after the first processing step.
  • the number of processing steps is not limited to two.
  • Various patterns can be considered, such as the next polishing process. In any pattern, after each step, the end shape of the glass substrate should be the desired shape.
  • a glass substrate for a magnetic disk and a perpendicular magnetic recording disk were manufactured through the following steps (1) to (; 11).
  • a multi-component glass substrate made of amorphous glass was prepared.
  • the glass type is aluminosilicate glass, and the specific chemical composition is Si02 force 5 wt%, A12 03 is 14.2 wt%, Na2O is 10.4 wt%, Li2O is 5.4 wt% %, ZR02 force .0 weight%, Sb203 force .4 weight%, As203 is 0.1 weight%.
  • This glass substrate was formed by a direct press method to obtain a disk-shaped glass substrate. Then, a disc-shaped glass substrate 1 having a hole in the center portion of the glass substrate using a grindstone and a circular hole in the center portion was obtained. Further, the outer peripheral end face and the inner peripheral end face were chamfered.
  • the surface roughness of the end surface (inner circumference, outer circumference) of the glass substrate 1 by brush polishing is about 1.
  • the surface of the glass substrate was ground by using # 1000 abrasive grains so that the flatness of the main surface was 3 mm, Rmax was about 2 mm, and Ra was about 0.2 m.
  • the flatness is the distance (height difference) between the highest part and the lowest part of the substrate surface in the vertical direction (direction perpendicular to the surface), and was measured with a flatness measuring device.
  • Rmax and Ra were measured using an atomic force microscope (AFM) (Digital Instruments Nanoscope).
  • the preliminary polishing step is a step of polishing the glass substrate that has been ground in the grinding step (3) and further roughed using a polishing pad for the first time.
  • a preliminary polishing step was performed using a polishing apparatus 3 capable of polishing both main surfaces of 100 to 200 glass substrates at a time.
  • a polyurethane soft polisher was used for the polishing pad.
  • As the polishing pad one containing zirconium oxide and cerium oxide in advance was used.
  • FIG. 5 (a) is a table showing the polishing conditions in Example 1.
  • the polishing liquid in the preliminary polishing (primary polishing) step was prepared by mixing water with cerium oxide polishing abrasive grains 40 having an average particle diameter of 1.2 inches.
  • the grain size of the abrasive grains 40 is preferably in the range of 1.0 to 1.4 mm.
  • the abrasive grains with a grain diameter exceeding 4 m were removed in advance.
  • the maximum value of the abrasive grains contained in the polishing liquid was 3 ⁇ 5 111, the average value was 1 ⁇ 2 111, and the 050 value was 1. It was l ⁇ m.
  • the load applied to the glass substrate 1 was 80 to 100 g / cm2, and the removal thickness of the surface portion of the glass substrate 1 was 20 to 40 ⁇ m.
  • end shape in the table of FIG. 5 indicates an end shape when only the polishing step is performed alone. Specifically, the shape of the end portion that occurs when the polishing step is performed using a glass substrate having a flat (flat) end portion is shown.
  • the “Result” in the table of FIG. 5 shows the shape of the edge of the glass substrate after a series of primary and secondary polishing steps.
  • the mirror polishing step is a step of further polishing the pre-polished glass substrate and polishing until the main surface of the glass substrate is mirror-finished.
  • a mirror polishing (secondary polishing) process was performed using a polishing apparatus 3 capable of polishing both main surfaces of 100 to 200 glass substrates at a time.
  • a polyurethane soft polisher was used for the polishing pad.
  • the polishing liquid in the mirror polishing process was prepared by adding colloidal silica particles having a grain diameter of 40 nm to ultrapure water.
  • the grain diameter of the colloidal silica particles is preferably in the range of 20 to 60 nm.
  • polishing is performed so that the edge shape force S ski jump shape is obtained in the preliminary polishing step, and in the subsequent mirror polishing step, polishing is performed so that the initially flat end shape is a roll-off shape.
  • the end shape of the finally obtained glass substrate is controlled so as to have a desired flat shape.
  • the glass substrate 1 was immersed in an aqueous NaOH solution having a concentration of 3 to 5 wt% for alkali cleaning. Cleaning was performed by applying ultrasonic waves. In addition, neutral detergent, pure water, pure water, It was cleaned by immersing it in each washing tank of propyl alcohol and isopropyl alcohol (steam-dried).
  • AFM Nanoscope manufactured by Digital Instruments Inc.
  • adhesion of colloidal silica abrasive grains was not confirmed. Also, no foreign matter such as stainless steel or iron was found.
  • the end of the glass substrate 1 may expand and rise due to the compressive stress generated on the substrate surface, and ski jump may occur. In such a case, a little roll-off shape may be left at the end of the preceding mirror polishing process rather than completely flattening.
  • the end shape after the secondary polishing process (mirror polishing process) and / or the primary polishing process (preliminary polishing) so that a flat end shape is obtained. The end shape after the step) may be adjusted.
  • the glass substrate 1 after the rapid cooling was immersed in sulfuric acid heated to about 40 ° C. and washed while applying an ultrasonic wave to complete the production of the glass substrate for a magnetic disk.
  • the magnetic disk glass substrate was inspected.
  • the surface roughness of the glass substrate for magnetic disks was measured with an AFM (Atomic Force Microscope)
  • the maximum peak height (Rp) was 1.8 nm
  • the arithmetic average roughness (Ra) was 0.25 nm.
  • the surface was in a clean specular state, and there were no foreign objects that obstructed the flying of the magnetic head or that caused thermal asperity failure.
  • the magnetic disk manufactured as described above was inspected.
  • a head crash test was carried out by flying over a magnetic disk using an inspection head with a flying height of 8 nm. As a result, no crash failure occurred in which the magnetic head did not come into contact with foreign matter.
  • a glide height test was performed on the magnetic disk.
  • the flying height of the inspection head is gradually reduced, and the flying height at which contact between the testing head and the magnetic disk occurs is confirmed.
  • the flying height was 4 nm from the inner edge portion to the outer edge portion of the magnetic disk.
  • the glide height was 3.7 nm.
  • FIG. 5B is a table showing the polishing conditions in the comparative example compared with the present example.
  • a magnetic disk was produced from the glass substrate obtained by the comparative example in the same manner as described above, and a head crash test was performed. As a result, the magnetic head contacted foreign matter and a crash failure occurred.
  • FIG. 5 (a) When FIG. 5 (a) is compared with FIG. 5 (b), the primary and secondary polishing have different particle diameters.
  • the polishing pad material used for the primary polishing is different.
  • the polishing pad hardness in Fig. 5 (b), which is a comparative example is 93C hardness in the primary polishing, 84C hardness in the secondary polishing, and the secondary polishing from the primary polishing.
  • the polishing pad hardness is lower.
  • the polishing pad hardness of FIG. 5 (a) which is an embodiment of the present invention, is 80C hardness in primary polishing, 84C hardness in secondary polishing, and secondary polishing is more than primary polishing. High polishing pad hardness.
  • the polishing pad hardness in FIG. 5 (a) is determined by primary polishing from the viewpoint of processing speed (polishing speed), substrate surface roughness, and the like. It is desirable to be within the range of ⁇ 82C hardness (Asker C hardness). It is desirable to be within the range of 82 ⁇ 86C hardness in the secondary polishing. In other words, regarding the hardness of the polishing pad used in the present invention (Asker C hardness), the polishing pad used in the secondary polishing has a higher hardness than the polishing pad used in the primary polishing! /, I like it! /
  • the shape of the glass substrate end that has become ski jump in the primary polishing changes in a direction to cancel out in the secondary polishing, and the roll-off value is 0.046 m.
  • the shape of the glass substrate end that was rolled off by the primary polishing was not offset by the secondary polishing, and the roll-off value increased to an absolute value—0.173 mm It has become.
  • the end shapes can be made closer to flat by canceling out the end shape changes that occur in the preceding and following polishing steps.
  • polishing apparatus since the double-side polishing apparatus 3 described with reference to FIG. 1 and the polishing pad 10 described with reference to FIG. 2 are used in the first embodiment, detailed description thereof will be omitted.
  • preliminary polishing is performed as a step of polishing the main surface of the glass substrate.
  • polishing steps Two polishing steps are performed: the (primary polishing) step and the mirror polishing (secondary polishing) step.
  • the structure of the double-side polishing apparatus 3 is almost the same in the process, the composition of the polishing abrasive grains contained in the used polishing liquid (slurry) and the polishing pad 10 are different. As a general tendency, the grain size of the abrasive grains becomes smaller and the hardness of the polishing pad 10 becomes softer as the subsequent process is performed.
  • the lowering of the end portion may occur more remarkably.
  • the roll-off generated in the primary polishing may not be offset, and the end portion may be in a shape that is still roll-off. Therefore, as one method for solving this problem, in the second embodiment, the size of the abrasive grains and the material and hardness of the polishing pad are changed in the secondary polishing, which is a subsequent process. By changing the polishing conditions, the roll-off generated in the primary polishing is changed in a direction that cancels out in the secondary polishing, and the end shape is brought close to flat.
  • FIG. 6 is a schematic view showing a second embodiment of the method for manufacturing a glass substrate for a magnetic disk according to the present invention using the double-side polishing apparatus 3 shown in FIG. Similar to the first embodiment, this method also includes a plurality of polishing steps shown in FIGS. 6 (a) and 6 (b). In these polishing steps, the main surface of the glass substrate 1 is polished by relatively moving the glass substrate 1 and the polishing pad 10 or 20 while supplying a polishing liquid containing the polishing grains 40 or 50.
  • Fig. 6 (a) shows a pre-polishing process in which polishing is performed so that the end of the main surface has a lowered shape (roll-off) compared to the central part, which corresponds to the preliminary polishing process in the second embodiment described later. To do.
  • FIG. 6 (b) shows a subsequent polishing process in which the lowered shape (roll-off) is changed in a direction to cancel, and the end of the glass substrate 1 is polished so as to approach the flat surface.
  • the preceding polishing step is realized by a set composed of the polishing abrasive grains 40 and the polishing pad 10
  • the subsequent polishing step is realized by a set composed of the polishing abrasive grains 50 and the polishing pad 20.
  • the roll-off shape in which the end portion is lowered compared to the central portion is grasped in advance, and FIG.
  • the grasping process for determining the hardness of the polishing pad 20 and the grain size of the abrasive grains 50 used in the subsequent polishing process of b) is further performed. May be included.
  • the processing conditions in the subsequent polishing process can be determined! /.
  • the hardness of the polishing pad 20 used in the subsequent polishing step of FIG. 6 (b) may be made lower than that of the polishing pad 10 used in the preceding polishing step of FIG. 6 (a). As described above, the hardness of the polishing pads 10 and 20 may be adjusted by the amount of bubbles mixed in these pads. Further, by the above-described grasping process, the grain size of the abrasive grains used in the subsequent polishing process of FIG. 6 (b) may be made smaller than the abrasive grains used in the preceding polishing process of FIG. 6 (a). That is, the second embodiment also determines the edge shape of the glass substrate obtained in the preceding polishing process in advance, and determines the hardness of the polishing pad and the abrasive grain size used in the subsequent polishing process. Process.
  • the glass having a flat end is temporarily assumed.
  • the glass substrate 100 is polished so that the end portion is raised compared to the center portion (ski jump).
  • the end of the main surface can be made substantially flat as shown in FIG. 6 (c).
  • the end of the main surface may have a lowered shape (tool off) compared to the central portion.
  • This is a polishing method in which an end shape change (ski jump) occurring in a chemical strengthening process performed further after the subsequent polishing process is anticipated and roll-off is performed in the subsequent polishing process. Even if it says roll-off, it means that the roll-off is closer to flat than the roll-off caused by the preliminary polishing process.
  • a magnetic disk is manufactured by forming at least a magnetic layer on the surface of a glass substrate obtained by the above-described method for manufacturing a glass substrate for a magnetic disk, the end portion is substantially A magnetic disk having a desired end shape, such as a flat magnetic disk, can be obtained.
  • a multi-component glass substrate made of amorphous glass was prepared.
  • the glass type is aluminosilicate glass, and the specific chemical composition is Si02 force 5 wt%, A12 03 is 14.2 wt%, Na2O is 10.4 wt%, Li2O is 5.4 wt% %, Zr02 force 0.0 wt%, Sb203 force .4 wt%, As203 was 0.1 wt%.
  • This glass substrate was molded by a direct press method to obtain a disk-shaped glass substrate. Then, a disc-shaped glass substrate 1 having a hole in the center portion of the glass substrate using a grindstone and a circular hole in the center portion was obtained. Further, chamfering was performed on the outer peripheral end surface and the inner peripheral end surface.
  • the surface roughness of the end surface (inner circumference, outer circumference) of the glass substrate 1 by brush polishing is about 1.
  • the surface of the glass substrate was ground by using # 1000 abrasive grains so that the flatness of the main surface was 3 mm, Rmax was about 2 mm, and Ra was about 0.2 m.
  • the flatness is the distance (height difference) between the highest part and the lowest part of the substrate surface in the vertical direction (direction perpendicular to the surface), and was measured with a flatness measuring device.
  • Rmax and Ra were measured using an atomic force microscope (AFM) (Digital Instruments Nanoscope).
  • the preliminary polishing step is a step of polishing the glass substrate that has been ground in the grinding step (3) and further roughed using a polishing pad for the first time.
  • a preliminary polishing step was performed using a polishing apparatus 3 capable of polishing both main surfaces of 100 to 200 glass substrates at a time.
  • a polyurethane soft polisher was used for the polishing pad.
  • As the polishing pad one containing zirconium oxide and cerium oxide in advance was used.
  • FIG. 7 (a) is a table showing polishing conditions in the second example.
  • the polishing liquid in the pre-polishing (primary polishing) process is a mixture of water and cerium oxide abrasive 40 with an average particle size of 1.2 in. Created by.
  • the grain size of the abrasive grains 40 is preferably within the range of 1.0 to 1.4111.
  • the load applied to the glass substrate 1 was 80 to 100 g / cm2, and the removal thickness of the surface portion of the glass substrate 1 was 20 to 40 ⁇ m.
  • end shape in the table of FIG. 7 indicates an end shape when only the polishing step is performed alone. Specifically, the shape of the end portion that occurs when the polishing step is performed using a glass substrate having a flat (flat) end portion is shown.
  • the “Result” in the table of FIG. 7 shows the edge shape of the substrate after a series of primary and secondary polishing steps.
  • the mirror polishing step is a step of further polishing the pre-polished glass substrate and polishing until the main surface of the glass substrate is mirror-finished.
  • a mirror polishing (secondary polishing) process was performed using a polishing apparatus 3 capable of polishing both main surfaces of 100 to 200 glass substrates at a time.
  • a polyurethane hard polisher was used for the polishing pad.
  • the polishing liquid in the mirror polishing process was prepared by adding cerium oxide particles with a grain diameter of 0.5 m to ultrapure water.
  • an abrasive with a particle diameter of 0.3 m or more.
  • the end shape was a ski jump shape.
  • the end shape is polished in a roll-off shape in the preliminary polishing step, and the initial flat end shape is changed to the ski jump shape in the subsequent mirror polishing step.
  • the end shape of the glass substrate finally obtained is controlled so as to have a desired shape! [6] (6) Cleaning process after mirror polishing
  • the glass substrate 1 was immersed in an aqueous NaOH solution having a concentration of 3 to 5 wt% to perform alkali cleaning. Cleaning was performed by applying ultrasonic waves. Furthermore, it was cleaned by immersing in neutral detergent, pure water, pure water, isopropyl alcohol, and isopropyl alcohol (steam-dried) cleaning baths. When the surface of the glass substrate 1 after cleaning was observed with an AFM (Nanoscope manufactured by Digital Instruments Inc.), adhesion of cerium oxide abrasive grains was not confirmed. Also, no foreign matter such as stainless steel or iron was found.
  • AFM Nanoscope manufactured by Digital Instruments Inc.
  • the surface of the glass substrate 1 may expand and rise, and ski jumps may occur. In such a case, a little roll-off shape may be left at the end of the preceding mirror polishing process, rather than being completely flat.
  • the glass substrate 1 after the rapid cooling was immersed in sulfuric acid heated to about 40 ° C., washed while applying ultrasonic waves, and the glass substrate for magnetic disks was Completed production.
  • the magnetic disk glass substrate was inspected.
  • the surface was in a clean mirror state, and there were no foreign objects that obstructed the flying of the magnetic head, or foreign objects that caused thermal asperity failure.
  • the magnetic disk manufactured as described above was inspected.
  • a head crash test was carried out by flying over a magnetic disk using an inspection head with a flying height of 8 nm. As a result, no crash failure occurred in which the magnetic head did not come into contact with foreign matter.
  • FIG. 7B is a table showing the polishing conditions in the comparative example compared with the second example.
  • FIG. 7 (b) Comparing Fig. 7 (a) and Fig. 7 (b), the material of the polishing pad used for the primary polishing is different for both primary and secondary polishing.
  • the polishing pad hardness in FIG. 7 (b) which is a comparative example, is 93C hardness in the primary polishing, 84C hardness in the secondary polishing, and the secondary polishing is more than the primary polishing.
  • the polishing pad hardness is lower.
  • FIG. 7 (a) which is the second embodiment of the present invention, is 90C hardness in the primary polishing, 72C hardness in the secondary polishing, and secondary polishing from the primary polishing. Although the polishing pad hardness is lower, the hardness value is different from Fig. 7 (b).
  • the polishing pad hardness in Fig. 7 (a) is preferably in the range of 90 to 96C hardness (Asker C hardness) in the primary polishing, and 70 to 86C hardness in the secondary polishing. It is desirable to be within range.
  • the shape force of the edge of the glass substrate that has been rolled off by the primary polishing changes in a direction to cancel by the secondary polishing, and the ski jumper has a ski jump value of 0.034 111. It is on the other hand, in the comparative example, the shape of the edge of the glass substrate that was rolled off in the primary polishing was not offset by the secondary polishing, and the roll-off value increased to an absolute value of -0.173 mm. It has become. As is apparent from this result, according to the second embodiment of the present invention, the force S that brings the end shape closer to flatness by canceling out the end shape change that occurs in the preceding and following polishing steps. it can.
  • the present invention is applicable to a method for manufacturing a glass substrate for a magnetic disk used as a recording medium for a computer or the like and a method for manufacturing a magnetic disk.

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

Abstract

Dans l'étape de rectification antérieure dans laquelle, lors de la fourniture d'un fluide de rectification contenant des grains d'abrasif de rectification de large diamètre, un substrat de verre et un patin de rectification doux sont déplacés suivant une relation relative de manière à obtenir une rectification, il se produit une morphologie telle que les bords de la principale surface du substrat de verre font saillie par rapport à la partie centrale de celle-ci (saut de ski). De la sorte, dans l'étape de rectification postérieure, à l'aide d'un fluide de rectification contenant des grains d'abrasif de rectification de petit diamètre et un patin de rectification plus dur que le patin de rectification mentionné ci-dessus, il est effectué une rectification de manière à ce que si un substrat de verre doté de parties de bord plates est rectifié, on obtient un substrat de verre dont les parties de bord de la principale surface descendent par rapport à la partie centrale de celle-ci (affaiblissement). Par conséquent, le substrat de verre peut être modifié afin d'obtenir une annulation du saut de ski généré dans l'étape de rectification antérieure, de manière à ce que la configuration des parties de bord soit proche de la planéité.
PCT/JP2007/067619 2006-09-19 2007-09-11 Procédé de production d'un substrat de verre pour un disque magnétique et procédé de fabrication d'un disque magnétique WO2008035586A1 (fr)

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CN106024031B (zh) * 2009-12-29 2019-01-22 Hoya株式会社 磁盘用玻璃基板的制造方法以及磁盘用玻璃基板
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CN105247615B (zh) * 2013-06-27 2018-06-22 Hoya株式会社 信息记录介质用玻璃基板及磁盘装置
CN104029117B (zh) * 2014-07-01 2015-04-29 中州大学 一种转角离合式永磁体吸盘
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KR102391872B1 (ko) * 2017-05-26 2022-04-29 삼성디스플레이 주식회사 유리 기판의 제조 방법 및 유리 기판 연마 장치

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CN101356040A (zh) 2009-01-28

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