JP6148345B2 - Manufacturing method of non-magnetic substrate - Google Patents

Description

  The present invention relates to a method for manufacturing a nonmagnetic substrate, and more specifically to a method for manufacturing a substrate including a step of polishing an end face of a nonmagnetic substrate.

  Today, a personal computer, a notebook personal computer, a DVD (Digital Versatile Disc) recording device, or the like has a built-in hard disk device for data recording. In particular, in a hard disk device used for portable equipment such as a notebook personal computer, a magnetic disk having a magnetic layer provided on a magnetic disk glass substrate is used. On the surface of the magnetic disk, magnetic recording information is recorded on or read from the magnetic layer of the magnetic disk by a magnetic head (DFH (Dynamic Flying Height) head) slightly lifted from this surface. As a substrate of this magnetic disk, a glass substrate is suitably used as a non-magnetic substrate because it has a property that it is less likely to undergo plastic deformation than a metal substrate or the like.

Today, in response to a request for an increase in storage capacity in a hard disk device, the density of magnetic recording is being increased. Along with this, the magnetic recording information area is miniaturized by extremely shortening the flying distance from the magnetic recording surface of the magnetic head. In such a glass substrate for a magnetic disk, the surface unevenness of the substrate is made as small as possible.
In a magnetic head used in a hard disk device, if there are minute irregularities on the surface of the magnetic disk, there is a risk that a known thermal asperity failure will occur, causing a malfunction in reproduction or making reproduction impossible. The cause of this thermal asperity failure is that the convex portion formed on the surface of the magnetic disk by foreign matter on the glass substrate causes adiabatic compression and expansion of the air near the head due to high-speed rotation of the magnetic disk, and the magnetic head generates heat. Due to That is, the thermal asperity failure can occur even when the magnetic head does not contact the magnetic disk.
Therefore, in order to prevent this thermal asperity failure, the surface of the magnetic disk needs to be finished to a very smooth surface free from foreign matter.

As a cause of foreign matter adhering to the surface of the magnetic disk glass substrate, not only the surface shape of the glass substrate but also the surface shape of the end surface of the glass substrate is considered. That is, when the edge of the glass substrate for magnetic disks is sharp or the surface shape of the edge is not smooth, the edge is rubbed against the wall surface of the resin case and the like. ) Occurs. Such fine particles and fine particles in the atmosphere are captured and accumulated on the end face of the magnetic disk glass substrate. The fine particles accumulated on the end surface of the magnetic disk glass substrate become a source of dust generation in a later process or after being mounted on a hard disk device, causing foreign matter to adhere to the surface of the disk substrate.
For this reason, when manufacturing a glass substrate for a magnetic disk, a chamfered surface is formed between the main surface and the side wall surface of the circular glass substrate, and the side wall surface and the chamfered surface are further polished. .

  By the way, a magnetically sensitive abrasive and a first magnet are placed in this order on a work surface of a nonmagnetic material such as aluminum or glass, and a second magnet is disposed below the nonmagnetic material. A magnetic polishing method in which the magnet is revolved while rotating above the processing surface via a magnetic force generated between the second magnet and the magnetically sensitive abrasive is moved relative to the processing surface. Known (Patent Document 1). Such a magnetic polishing method is said to be able to simultaneously improve the surface accuracy and shape accuracy of the work surface by a simple method.

  Further, a magnetic polishing method is known as a method for polishing an end face of a circular glass substrate. For example, in Patent Document 2, in a step of polishing an inner peripheral end face of a glass substrate, a magnetic field is formed on the inner peripheral side of a central circular hole, and polishing including magnetic particles and abrasive grains is performed in the circular hole by the magnetic field. Magnetic polishing that holds the agent and moves the magnetic field with respect to the inner peripheral side end surface of the circular hole, thereby moving the abrasive with respect to the inner peripheral side end surface of the circular hole to polish the inner peripheral side end surface of the circular hole It is described that polishing is performed by a method. According to such a magnetic polishing method, it is said that the inner peripheral side end face of the circular hole at the center of the glass substrate can be easily and satisfactorily polished.

JP 2008-290162 A JP 2005-50501 A

The inventor of the present application forms a magnetic field so that a magnetic force line advances in the thickness direction of the glass substrate using a magnetic field generating means, and holds the magnetic functional fluid including abrasive grains in the magnetic field, and the end surface of the glass substrate When the glass substrate end face polishing treatment was performed by moving it relative to the magnetic functional fluid in contact with the magnetic functional fluid, the processing rate was high and the surface properties of the end face were excellent. It was confirmed that it was obtained.
However, it has been found that the chamfered surface processing rate gradually decreases particularly when the above-described end surface polishing treatment is performed continuously by a single wafer processing for many glass substrates. This problem is considered to occur not only in the glass substrate but also in a nonmagnetic substrate using another material (for example, an aluminum alloy).

  Then, an object of this invention is to provide the manufacturing method of a board | substrate which can suppress the fall of the processing rate of a chamfering surface, when polishing the end surface of a board | substrate continuously.

  The inventor of the present application diligently studied the cause of a decrease in the processing rate of the end surface of the glass substrate when the end surface polishing treatment of the glass substrate is continuously performed using a magnetic functional fluid. As a result, the cause of the decrease in the processing rate was estimated as follows. That is, in the end surface polishing process, the magnetic flux density decreases in a region where a part of the end surface of the glass substrate crosses the magnetic field lines. In such a region, the holding force against the magnetic functional fluid by the magnetic field tends to be reduced. That is, the pressing force of the magnetic functional fluid on the processed part of the substrate tends to be small. Such a tendency becomes more prominent in the chamfered surface when the side wall surface and the chamfered surface are formed at the end of the substrate. On the other hand, since the abrasive grains that contribute to polishing are non-magnetic, they are basically not held by a magnetic field, but are held by a pressing force between the magnetic particles and the substrate to be processed. For this reason, when the pressing force decreases, the abrasive grains easily escape from the magnetic functional fluid. In addition, over time, the concentration of the abrasive grains in the portion where the pressing force is small gradually decreases. As a result, it was estimated that the polishing processing rate would decrease. Moreover, since the said pressing force with respect to a chamfering surface tends to become lower than a side wall surface, it was estimated that it appeared especially notably with respect to a chamfering surface. Based on this presumed cause, the inventor of the present application has further pursued research and found that the method for manufacturing a glass substrate for a magnetic disk according to the present invention can suppress a reduction in the chamfered surface processing rate in end face polishing.

1st aspect of this invention manufactures the nonmagnetic board | substrate including the end surface grinding | polishing process which grind | polishes the end surface of the plate-shaped nonmagnetic board | substrate which has a side wall surface and the chamfering surface formed between the main surface and the side wall surface. Is the method.
In the end surface polishing treatment, the substrate is formed in a state in which a magnetic field is formed using magnetic field generation means so that magnetic lines of force advance in the thickness direction of the substrate, and the magnetic functional fluid including abrasive grains is held in the magnetic field. The end surface of the substrate is polished by bringing the end surface of the substrate into contact with the magnetic functional fluid and relatively moving the substrate and the magnetic functional fluid. Here, the abrasive grains are supplied to the magnetic functional fluid during the end face polishing process.
The magnetic functional fluid may be any functional fluid that responds to a magnetic field. For example, MRF (Magneto-rheological Fluid), MF (Magnetic Fluid), MCF (Magnetic Compound Fluid) Fluid) or the like.

  In that case, you may supply the said abrasive grain by supplying the liquid containing an abrasive grain during the said end surface grinding | polishing process.

  The temperature of the liquid supplied during the end surface polishing process may be room temperature or lower.

  In the end face polishing process, the polishing abrasive grains are supplied toward a position where the end face of the substrate is in contact with the magnetic functional fluid and along a moving direction of the end face of the substrate in contact with the magnetic functional fluid. May be. Examples of the supply method include a method of flowing out abrasive grains or a liquid containing the abrasive grains toward the position (for example, a method of spraying), a method of dropping, and the like.

According to a second aspect of the present invention, there is provided a nonmagnetic substrate including an end surface polishing process for polishing an end surface of a plate-like nonmagnetic substrate having a side wall surface and a chamfered surface formed between the main surface and the side wall surface. Is the method.
In the end surface polishing treatment, the magnetic functional fluid including polishing abrasive grains and the substrate are immersed in a liquid including polishing abrasive grains so that the lines of magnetic force advance in the thickness direction of the substrate using the magnetic field generating means. In the state where the magnetic functional fluid containing abrasive grains is held in the magnetic field, the substrate and the magnetic functional fluid are brought into contact with each other by bringing the end surface of the substrate into contact with the magnetic functional fluid. The end face of the substrate is polished by relative movement.

  In the first or second aspect of the present invention, the magnetic field generating means is a magnet arranged in a state where the N-pole surface and the S-pole surface are spaced apart from each other in the thickness direction of the substrate. A pair may be included.

  In the first or second aspect of the present invention, a spacer made of a non-magnetic material may be provided between the N pole surface and the S pole surface of the magnet pair.

  The substrate may have a disk shape having a circular inner hole. At this time, the magnetic field generating means is provided in the inner hole of the substrate, and an inner peripheral side magnetic field line that advances in the thickness direction of the substrate advances around an inner peripheral end surface that is a side wall surface of the inner hole. And / or an inner peripheral means for forming a magnetic field and / or an outer peripheral side surface of the substrate, and a magnetic field is applied around the outer peripheral end surface of the substrate so that outer peripheral magnetic lines of force advance in the thickness direction of the substrate. You may have the outer peripheral side means to form. Further, the inner peripheral end face and / or the outer peripheral end face of the substrate is held in the state where the magnetic functional fluid is held in a magnetic field formed by each of the inner peripheral side means and / or the outer peripheral side means. Both the inner peripheral end face and / or the outer peripheral end face may be polished.

  In addition, from the viewpoint different from the above, the inventor of the present application also decreases the processing rate of the chamfered surface of the glass substrate when the end surface grinding process of the glass substrate is continuously performed using the magnetic functional fluid. We studied the cause of this. As a result, the reason why the processing rate of the chamfered surface of the glass substrate decreased was estimated as follows. That is, in the above-described end surface polishing treatment, the side wall surface of the end surface of the glass substrate is polished by a lump of magnetic functional fluid in a region (referred to as “region A1”) where the glass substrate does not cross the lines of magnetic force in plan view. The mass of the magnetic functional fluid in the region A1 has a high holding power of the mass due to the magnetic field because the magnetic field lines are not cut off, and the polishing is performed stably by the abrasive grains, so that the polishing processing rate is high. On the other hand, the chamfered surface of the end surface of the glass substrate is polished by a mass of a magnetic functional fluid in a region (referred to as “region A <b> 2”) where the glass substrate crosses the lines of magnetic force in plan view. The mass of the magnetic functional fluid in the region A2 has a relatively weak holding force due to the magnetic field because the magnetic field lines are at least partially cut off, and the mass collapses and deforms (plastic deformation), and the pressing force on the glass substrate decreases. It is easy to do. For this reason, since it is difficult to stably perform polishing with the abrasive grains in the region A2, it is considered that the processing rate of the chamfered surface is lower than that of the side wall surface. Based on this presumed cause, the inventor of the present application has further researched and modified the shape of the magnetic functional fluid deformed by contact with the substrate so that the pressing force against the substrate is kept constant, thereby chamfering the surface. It was found that a reduction in the processing rate of the steel can be suppressed.

According to a third aspect of the present invention, there is provided a nonmagnetic substrate including an end surface polishing process for polishing an end surface of a plate-like nonmagnetic substrate having a side wall surface and a chamfered surface formed between the main surface and the side wall surface. Is the method.
The end surface polishing treatment uses the magnetic field generating means to form a magnetic field so that a magnetic line of force advances in the thickness direction of the substrate, and to hold the magnetic functional fluid containing abrasive grains in the magnetic field. A process of polishing the end face of the substrate by forming a fluid mass, bringing the end surface of the substrate into contact with the mass of the magnetic functional fluid, and moving the substrate and the mass of the magnetic functional fluid relative to each other. It is. Here, the shape of the mass of the magnetic functional fluid deformed by contact with the substrate is corrected so as to maintain a constant pressing force against the substrate.

  At that time, the shape of the mass of the magnetic functional fluid may be corrected by bringing a jig into contact with the deformed magnetic functional fluid. Also, the shape of the magnetic functional fluid mass may be modified by supplying additional magnetic functional fluid mass.

According to a fourth aspect of the present invention, there is provided a nonmagnetic substrate manufacturing method including an end surface polishing process for polishing an end surface of a plate-like nonmagnetic substrate having a side wall surface and a chamfered surface formed between the main surface and the side wall surface. It is.
The end surface polishing treatment uses the magnetic field generating means to form a magnetic field so that a magnetic line of force advances in the thickness direction of the substrate, and to hold the magnetic functional fluid containing abrasive grains in the magnetic field. A process of polishing the end face of the substrate by forming a fluid mass, bringing the end surface of the substrate into contact with the mass of the magnetic functional fluid, and moving the substrate and the mass of the magnetic functional fluid relative to each other. And
The shape of the mass of the magnetic functional fluid deformed by contact with the substrate is corrected so as to return to the original shape.

According to a fifth aspect of the present invention, there is provided a nonmagnetic substrate manufacturing method including an end surface polishing process for polishing an end surface of a plate-like nonmagnetic substrate having a side wall surface and a chamfered surface formed between the main surface and the side wall surface. It is.
The end surface polishing treatment uses the magnetic field generating means to form a magnetic field so that a magnetic line of force advances in the thickness direction of the substrate, and to hold the magnetic functional fluid containing abrasive grains in the magnetic field. A process of polishing the end face of the substrate by forming a fluid mass, bringing the end surface of the substrate into contact with the mass of the magnetic functional fluid, and moving the substrate and the mass of the magnetic functional fluid relative to each other. And
The shape of the magnetic functional fluid mass is changed by bringing a jig into contact with the magnetic functional fluid mass.

  The jig may be brought into contact with the mass of the magnetic functional fluid so that the tip of the jig is inserted into the mass of the magnetic functional fluid.

  In the third to fifth aspects of the present invention, the magnetic field generating means is a magnet arranged in a state where the N-pole surface and the S-pole surface are spaced apart from each other in the thickness direction of the substrate. A pair may be included.

  In the third to fifth aspects of the present invention, it is preferable that a spacer made of a nonmagnetic material is provided between the N pole surface and the S pole surface of the pair of magnets.

  In the third to fifth aspects of the present invention, the substrate may have a disk shape having a circular inner hole. At this time, the magnetic field generating means is provided in the inner hole of the substrate, and an inner peripheral side magnetic field line that advances in the thickness direction of the substrate advances around an inner peripheral end surface that is a side wall surface of the inner hole. And / or an inner peripheral means for forming a magnetic field and / or an outer peripheral side surface of the substrate, and a magnetic field is applied around the outer peripheral end surface of the substrate so that outer peripheral magnetic lines of force advance in the thickness direction of the substrate. You may have the outer peripheral side means to form. Further, the inner peripheral end face and / or the outer peripheral end face of the substrate is held in a state where the mass of the magnetic functional fluid is held in a magnetic field formed by each of the inner peripheral means and / or the outer peripheral means. Both the inner peripheral end surface and / or the outer peripheral end surface of the substrate may be polished.

The figure which shows the external appearance shape of the glass substrate for magnetic discs of 1st Embodiment. The expanded sectional view of the edge part of the outer peripheral side of the glass substrate for magnetic discs of 1st Embodiment. The figure which shows the flow of one Embodiment of the manufacturing method of the glass substrate for magnetic discs. The figure explaining the grinding | polishing method of the end surface grinding | polishing of 1st Embodiment. The figure explaining the grinding | polishing method of the end surface grinding | polishing of 1st Embodiment. The figure explaining the grinding | polishing method of the end surface grinding | polishing of 1st Embodiment. The figure explaining the grinding | polishing method of the end surface grinding | polishing of 1st Embodiment. The figure explaining the grinding | polishing method of the end surface grinding | polishing which concerns on the modification of 1st Embodiment. The figure explaining the grinding | polishing method of the end surface grinding | polishing which concerns on the modification of 1st Embodiment. The figure explaining the reason for which the processing rate of a chamfering surface falls, when not correcting the shape of polishing fluid in the end surface grinding | polishing of a glass substrate in 2nd Embodiment. The figure which shows the structural example in the case of correcting the shape of polishing fluid using a shape correction apparatus in 2nd Embodiment. The figure explaining the shape correction process of the polishing fluid using the shape correction apparatus in 2nd Embodiment. The figure which shows the structural example in the case of correcting the shape of polishing fluid using a supply apparatus in 2nd Embodiment. The figure which shows the structural example in the case of correcting the shape of a polishing fluid using a supply apparatus, when grind | polishing the end surface of the glass substrate which comprises a laminated body in 2nd Embodiment. The figure explaining the method of calculating | requiring the curvature radius of the shape of the part between a side wall surface and a chamfering surface.

(First embodiment)
Hereinafter, a method for manufacturing a magnetic disk substrate will be described in detail as an embodiment of the method for manufacturing a nonmagnetic substrate of the present invention. In the following description, a case where a glass substrate is used as the magnetic disk substrate will be described. However, the present invention is not limited to this, and an aluminum synthetic substrate may be used.
[Magnetic disk glass substrate]
Aluminosilicate glass, soda lime glass, borosilicate glass, or the like can be used as the material for the magnetic disk glass substrate in the present embodiment. In particular, aluminosilicate glass can be suitably used in that it can be chemically strengthened and a glass substrate for a magnetic disk excellent in flatness of the main surface and strength of the substrate can be produced.

Although the composition of the glass material used for the glass substrate for magnetic disk of the present embodiment is not limited, the glass substrate of the present embodiment is preferably composed of SiO ₂ , Li ₂ O, Na ₂ O, and And at least one alkaline earth metal oxide selected from the group consisting of MgO, CaO, SrO and BaO, and the molar ratio of the content of CaO to the total content of MgO, CaO, SrO and BaO (CaO / (MgO + CaO + SrO + BaO )) Is 0.20 or less, and an amorphous aluminosilicate glass having a glass transition temperature of 650 ° C. or more may be used.
Also, in terms of% by mass on the oxide _basis, SiO 2: 45.60 to 60%, and _Al 2 _O 3: _7~20%, and _B 2 _O 3: less than 1.00 to 8%, and _P 2 _{O 5} : 0.50 to 7%, and TiO ₂ : 1 to 15%, and the total amount of RO: 5 to 35% (wherein R is Zn and Mg), and the content of CaO is 3.00 %, BaO content is 4% or less, PbO component, As ₂ O ₃ component and Sb ₂ O ₃ component and Cl ⁻ , NO ⁻ , SO ²⁻ , F ⁻ component are not contained, and the main crystal phase RAl ₂ O ₄ , R ₂ TiO ₄ (where R is one or more selected from Zn and Mg), and the crystal grain size of the main crystal phase is in the range of 0.5 nm to 20 nm. The crystallinity is 15% or less and the specific gravity is 2.95 or less. It may be a crystallized glass characterized by the following.

FIG. 1A shows the appearance of the magnetic disk glass substrate 1 of the embodiment. As shown in FIG. 1A, a glass substrate 1 for a magnetic disk in the present embodiment is a donut-shaped thin glass substrate in which an inner hole 2 is formed. Although the size of the glass substrate for magnetic disks is not ask | required, for example, it is suitable as a glass substrate for magnetic disks with a nominal diameter of 2.5 inches.
FIG. 1B is an enlarged view showing a cross section of an end portion on the outer peripheral side of the glass substrate for magnetic disk of the embodiment. As shown in FIG. 1B, the magnetic disk glass substrate includes a pair of main surfaces 1p, side wall surfaces 1t arranged along a direction orthogonal to the pair of main surfaces 1p, and a pair of main surfaces 1p and sides. It has a pair of chamfered surfaces 1c arranged between the wall surface 1t. Although not shown, a side wall surface and a chamfered surface are similarly formed on the inner peripheral side end of the magnetic disk glass substrate. The angle (chamfer angle) formed by each chamfered surface 1c with respect to the side wall surface 1t is the same, for example, 40 to 50 degrees. The chamfer angle is typically 45 degrees as shown. Note that the chamfered surface may be formed in an arc shape in a sectional view.

  The thickness of the magnetic disk glass substrate of the present embodiment is not particularly limited. For example, in the case of a magnetic disk glass substrate having a nominal size of 2.5 inches, for example, 0.8 mm, 0.635 mm, In the case of a glass substrate for a magnetic disk having a nominal diameter of 3.5 inches, it is, for example, 0.5 to 3.0 mm. The same applies to the case where an aluminum alloy substrate is used as the nonmagnetic substrate.

[Method of manufacturing glass substrate for magnetic disk]
Next, with reference to FIG. 2, the flow of the manufacturing method of the glass substrate for magnetic discs is demonstrated. FIG. 2 is a diagram showing a flow of an embodiment of a method for manufacturing a glass substrate for magnetic disk.
As shown in FIG. 2, first, a plate-shaped glass blank having a pair of main surfaces is formed (step S10). Next, the formed glass blank is scribed to produce an annular glass substrate (step S20). As a result, a magnetic disk glass substrate (hereinafter simply referred to as a glass substrate) having a circular through hole at the center is obtained. Next, shape processing (chambering processing) is performed on the scribed glass substrate (step S30). Next, the glass substrate is ground with fixed abrasive grains (step S40). Next, the end surface of the glass substrate is polished (step S50). Next, 1st grinding | polishing is performed to the main surface of a glass substrate (step S60). Next, chemical strengthening is performed on the glass substrate after the first polishing (step S70). Next, the second polishing is performed on the chemically strengthened glass substrate (step S80). Through the above processing, a magnetic disk glass substrate that satisfies the required surface irregularities can be obtained. In addition, a circular glass substrate is produced from a glass blank by the process from a glass blank shaping | molding process (step S10) to a shape processing process (step S30). Hereinafter, each process will be described in detail.

(A) Glass blank forming process (step S10)
For example, after a plate glass is formed by a float method, a glass base plate having a predetermined shape that is a base of a magnetic disk glass substrate is cut out from the plate glass. Instead of the float process, for example, a glass blank (glass blank) may be formed by press molding using an upper mold and a lower mold. In addition, a glass base plate can also be manufactured not only using these methods but using well-known manufacturing methods, such as a downdraw method, a redraw method, and a fusion method.
In addition, you may perform a rough grinding process with respect to both the main surfaces of a glass base plate as needed.

(B) Scribe process (step S20)
Next, the scribe process will be described. In the scribing process after the glass blank forming process, the formed glass blank is subjected to a scribing process using a scriber to obtain an annular glass substrate in which circular inner holes are formed. An annular glass substrate can also be obtained by forming a circular inner hole on the glass blank using a core drill or the like.

(C) Shape processing (step S30)
Next, shape processing will be described. The shape processing includes chamfering (chamfering of the outer peripheral end surface and the inner peripheral end surface) for the end portion of the glass substrate after the scribe processing. A chamfering process is a shape process which chamfers with a diamond grindstone in the outer peripheral end surface and inner peripheral end surface of the glass substrate after a scribe process. The chamfering inclination angle is, for example, 40 to 50 degrees with respect to the main surface, and is preferably about 45 degrees. By this shape processing, a glass substrate having a predetermined cross-sectional shape is produced.

(D) Precision grinding process (step S40)
In the fine grinding process, the main surface of the glass substrate is ground using a double-side grinding machine having a known planetary gear mechanism with an upper surface plate, a lower surface plate, an internal gear, a carrier, and a sun gear. . Specifically, the main surface on both sides of the glass substrate is ground while the outer peripheral end surface of the glass substrate is held in the holding hole provided in the holding member of the double-side grinding apparatus. The machining allowance by grinding is, for example, about several μm to 100 μm. The particle size of the fixed abrasive used for the fine grinding process is, for example, about 10 μm. The double-sided grinding apparatus has a pair of upper and lower surface plates (upper surface plate and lower surface plate), and a glass substrate is sandwiched between the upper surface plate and the lower surface plate. The glass substrate is sandwiched between the upper surface plate and the lower surface plate in a state where the glass substrate is held in a holding hole provided in the disk-shaped carrier. And by moving either the upper surface plate or the lower surface plate, or both, the glass substrate and each surface plate can be moved relatively to grind both main surfaces of the glass substrate. it can.

(E) End face polishing process (step S50)
Next, the end face polishing process will be described. In end surface polishing, a magnetic field is formed by using magnetic field generating means so that magnetic lines of force advance in the thickness direction of the glass substrate, and a magnetic functional fluid (hereinafter referred to as “polishing fluid”) containing abrasive grains in the magnetic field. The end surface of the glass substrate is polished by being held and moved relative to the polishing fluid in a state where the end surface of the glass substrate is in contact with the polishing fluid. The polishing fluid forms a lump in the magnetic field. As the abrasive grains contained in the polishing fluid, for example, fine particles such as cerium oxide and zirconium oxide are used. Moreover, the machining allowance by end surface grinding | polishing is 10 micrometers or less, More preferably, it is 5 micrometers or less. By polishing the end face, removing contamination such as dirt and scratches on the end face of the glass substrate will prevent the occurrence of thermal asperity failure and cause corrosion such as sodium and potassium. The occurrence of ion precipitation can be prevented. The end surface polishing of this embodiment can be polished in a shorter time than the conventional end surface polishing method, for example, the conventional magnetic polishing method of polishing the end surface of the glass substrate with a polishing slurry using a brush. Efficiency is good. The end face polishing will be described later.

(F) First polishing process (step S60)
Next, a first polishing process is performed on the main surface of the glass substrate. In the first polishing process, the main surfaces on both sides of the glass substrate are polished using a double-side polishing apparatus equipped with a planetary gear mechanism. In the first polishing process, for example, loose abrasive grains such as cerium oxide abrasive grains or zirconia abrasive grains and a resin polisher are used. The first polishing removes cracks and distortions remaining on the main surface when, for example, fine grinding is performed.

(G) Chemical strengthening process (step S70)
The glass substrate can be appropriately chemically strengthened. As the chemical strengthening liquid, for example, a molten liquid obtained by heating potassium nitrate, sodium nitrate, or a mixture thereof can be used. Then, by immersing the glass substrate in the chemical strengthening solution, lithium ions and sodium ions in the glass composition on the surface of the glass substrate are converted into sodium ions and potassium ions having relatively large ion radii in the chemical strengthening solution, respectively. By replacing each, a compressive stress layer is formed in the surface layer portion, and the glass substrate is strengthened.
The timing of performing the chemical strengthening treatment can be determined as appropriate. However, if the polishing treatment is performed after the chemical strengthening treatment, the foreign matter fixed to the surface of the glass substrate by the chemical strengthening treatment can be removed together with the smoothing of the surface. This is particularly preferable because it can be performed. Further, the chemical strengthening treatment may be performed as necessary, and may not be performed.

(H) Second polishing (final polishing) process (step S80)
Next, 2nd grinding | polishing is given to the glass substrate after a chemical strengthening process. The second polishing is intended for mirror polishing of the main surface. Also in the second polishing, a double-side polishing apparatus having the same configuration as the double-side polishing apparatus used for the first polishing is used. In the second polishing process, it is preferable to make the particle size of the loose abrasive grains and the hardness of the resin polisher of the polishing pad smaller than in the first polishing process. By doing in this way, the surface roughness of a glass substrate can be made extremely small.

As the free abrasive grains used for the second polishing treatment, for example, fine particles such as colloidal silica are used.
The second polishing process is not necessarily an essential process, but it is preferable that the second polishing process is performed in that the level of surface irregularities on the main surface of the glass substrate can be further improved. Thereafter, by cleaning, a glass substrate for a magnetic disk is obtained. Note that the glass substrate is polished so that the arithmetic average roughness Ra of the surface roughness of the glass substrate after the second polishing treatment is 0.15 nm or less, thereby producing a glass substrate for a magnetic disk having a small surface roughness. This is preferable.

[End polishing]
The end surface polishing performed in step S50 will be described in more detail. FIG. 3 and FIG. 4 are diagrams for explaining a polishing method for end face polishing according to the present embodiment, and are diagrams for easy understanding.
The polishing apparatus 10 that performs end face polishing polishes the end face of the glass substrate using a magnetic field generating means and a polishing fluid. 3 and 4 illustrate polishing of the outer peripheral end face of the glass substrate. An outline of the polishing apparatus 10 that performs end face polishing will be described. As shown in FIG. 3, the polishing apparatus 10 includes a pair of magnets 12 (N poles) and magnets 14 (S poles) that are cylindrical permanent magnets, and a spacer 16. Between the pair of magnets 12 (N pole) and magnet 14 (S pole), a magnetic field is formed around the spacer 16 from which magnetic lines of force are directed from the magnet 12 to the magnet 14. In the example shown in FIG. 3, a pair of magnets arranged in the thickness direction of the glass substrate G so that the N-pole surface and the S-pole surface are spaced apart from each other is used as the magnetic field generating means. A spacer 16 made of a non-magnetic material is provided between the magnets 12 and 14 so that the separation distance between the N pole end face of the magnet 12 and the S pole end face of the magnet 14 is a predetermined distance. It is done.

As shown in FIG. 4, when end face polishing is performed using the polishing apparatus 10, the glass substrate G to be end face polished is held by a rotating body (not shown) and rotated around the central axis.
A magnetic field is formed so that the lines of magnetic force directed from the magnet 12 to the magnet 14 advance, and the outer peripheral end of the glass substrate G held by the rotating body is held in the magnetic fluid while the polishing fluid lump F is held in the magnetic field. The outer peripheral end surface of the glass substrate G is polished by repeatedly contacting the glass substrate G and the lump F of the polishing fluid by being brought into contact with F repeatedly. As shown in FIG. 4, the lump F of the polishing fluid includes magnetic fine particles 5a and polishing abrasive grains 5b.
The polishing apparatus 10 and a rotating body (not shown) that holds the glass substrate G are mechanically connected to a driving motor (not shown). For example, the rotating directions of the polishing apparatus 10 and the rotating body that holds the glass substrate G are rotated in opposite directions, and the relative speed of the peripheral speed between the polishing apparatus 10 and the rotating body is rotated at 40 to 500 m / min. preferable. Note that the polishing apparatus 10 is fixed, whereby the lump F of the polishing fluid is fixed, and the glass substrate G is rotated, so that the outer peripheral end surface of the glass substrate G and the lump F of the polishing fluid can be relatively moved. Good.

  In the examples shown in FIGS. 3 and 4, a permanent magnet is used as the magnetic field generating means, but an electromagnet can also be used.

As a polishing fluid used for end face polishing, for example, a nonpolar oil containing ³ to 5 g / cm ^{3 of} magnetic fine particles containing Fe (iron) element having an average particle diameter (D50) of 0.1 to 10 μm, and a surfactant are used. The contained fluid is used. Nonpolar oil or polar oil has a viscosity of 100 to 1000 (mPa · sec) at room temperature (20 ° C.), for example.
Since the polishing fluid becomes a lump F having relatively high elastic characteristics due to the magnetic field from the magnet 12 toward the magnet 14, the polishing fluid can be efficiently polished by pressing the end face of the glass substrate against the lump of polishing fluid. That is, the processing rate can be made higher than before, and polishing can be performed efficiently.

As abrasive grains contained in the polishing fluid, known abrasive grains of glass substrates such as cerium oxide, colloidal silica, zirconia oxide, alumina abrasive grains, and diamond abrasive grains can be used. The average particle diameter (D50) of the abrasive grains is, for example, 0.5 to 10 μm. By using the abrasive grains in this range, the end face of the glass substrate can be satisfactorily polished. The abrasive grains are contained in the polishing fluid, for example, 3 to 15 [Vol%].
The average particle size (D50) means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% calculated from the smaller particle size.

  The viscosity of the polishing fluid is preferably 1000 to 2000 [mPa · sec] at room temperature (20 ° C.) in that a lump F of the polishing fluid is formed and end face polishing is efficiently performed. When the viscosity is low, it is difficult to form the lump F, and it is difficult to perform polishing while being relatively moved while being pressed against the end face of the glass substrate G. On the other hand, when the viscosity of the polishing fluid is excessively high, the lump F of the polishing fluid is formed along the shape of the edge of the glass substrate G during polishing, and it is difficult to form a uniform pressed state. Further, the magnetic flux density of the magnetic field generated by the magnetic field generating means is preferably 0.3 to 0.9 [Tesla] in that the polishing fluid lump F is formed and the end face polishing is performed efficiently. Further, the yield stress of the magnetic functional fluid is preferably 30 kPa or more, more preferably 30 to 60 kPa, in a state where a magnetic field of 0.4 [Tesla] is applied.

Here, the yield stress (yield shear stress) of the polishing fluid, that is, the magnetic functional fluid, can be determined by the following method, for example. Using a rotary viscometer that incorporates magnetic field generation means (permanent magnet, electromagnet, etc.) capable of applying a 0.4 [Tesla] magnetic field, the relationship between the shear rate and shear stress of the magnetic functional fluid is determined. The yield stress of the magnetic functional fluid can be obtained by approximating the relationship between the obtained shear rate and the shear stress using a known Casson equation.
The yield stress affects the pressure that the glass substrate receives from the polishing fluid, that is, shear stress, when the polishing fluid held by the magnetic field and the outer peripheral end surface of the glass substrate move relative to each other. Therefore, the higher the yield stress of the polishing fluid (the higher the shear stress when the polishing fluid flows), the more efficient polishing is achieved by contact between the abrasive grains and the glass substrate, and the end face polishing processing rate is improved. Can do.

In the end surface polishing of the glass substrate using the polishing fluid described above, when the end surfaces of a plurality of glass substrates that are workpieces are continuously polished by a single wafer processing, the processing rate may be lowered. The reason why the machining rate is lowered will be described with reference to FIG. FIG. 5 is a diagram conceptually showing the lines of magnetic force when the outer peripheral end surface of the glass substrate G is being polished.
During polishing of the end face of the glass substrate, a lump of polishing fluid contacts the end of the glass substrate G while rotating at a relatively high speed as the polishing apparatus 10 rotates, and a part of the lump is discharged to the outside little by little. As the polishing fluid is discharged, the abrasive grains contained in the polishing fluid held by the magnetic field are also released to the outside. In particular, as shown in FIG. 4, when polishing is performed by interposing an end portion of a glass substrate that is a non-magnetic material between N-pole and S-pole magnets, the abrasive grains contained in the polishing fluid are The reason why it is likely to be released to the outside (that is, the concentration of the abrasive grains in the polishing fluid decreases) will be described with reference to FIG.

In FIG. 5, in the end surface polishing in which the glass substrate G is pushed into the polishing fluid and the glass substrate G and the polishing fluid are moved relative to each other, lines of magnetic force generated between the N pole magnet 12 and the S pole magnet 14 are used. The edge part of a glass substrate interposes so that it may cross. At this time, in the area A1 of FIG. 5, since the magnetic fine particles in the polishing fluid are arranged along the lines of magnetic force , the holding power of the abrasive grains by the magnetic field is high, and the glass substrate G is removed from the polishing fluid. It is easy to receive a reaction force (that is, a pressing force against the glass substrate G). On the other hand, in the region A2, because the edge of the glass substrate crosses the magnetic field lines, the arrangement of the magnetic fine particles in the polishing fluid collapses, thereby locally reducing the holding power of the abrasive grains by the magnetic field, The abrasive grains are easily released to the outside.
As a result, when end face polishing is continuously performed for a plurality of glass substrates G, the polishing fluid in the region A1 having a high holding power by the magnetic field maintains a high concentration of the abrasive grains, but the holding power by the magnetic field. As for the polishing fluid in the region A2 where the decrease in polishing concentration, the concentration of polishing abrasive grains decreases. Therefore, the side wall surface Co1 of the glass substrate G included in the region A1 does not decrease the processing rate even if the polishing is continuously performed, but the chamfered surfaces Co2 and Co3 of the glass substrate G included in the region A2 are continuous. When polishing is performed, the amount of polishing abrasive grains in the polishing fluid decreases, and the processing rate decreases accordingly.

Therefore, the end surface polishing process of this embodiment is performed while supplying abrasive grains from the outside during polishing. That is, by supplying new abrasive grains from the outside to the area A2 in which the slurry concentration is likely to decrease in continuous processing in FIG. 5, the chamfered surface processing rate decreases when continuously performing end surface polishing. Can be suppressed. The supply of the abrasive grains during polishing may be performed by supplying the abrasive grains themselves, or may be performed by supplying a liquid containing the abrasive grains. Examples of the supply method include, but are not limited to, a method of flowing out abrasive grains or a liquid containing the abrasive grains toward the region A2 (for example, a method of spraying), a method of dropping, and the like.
An example of a method for supplying abrasive grains by supplying a liquid containing abrasive grains is shown in FIG. FIG. 6 shows an example in which the polishing fluid is supplied to the polishing apparatus 10 from the nozzle of the supply apparatus 30 in a plan view. In the example shown in FIG. 6, the liquid containing the additional abrasive grains is supplied toward a position where the lump of polishing fluid held in the magnetic field and the outer peripheral end of the glass substrate G are in contact with each other. Preferably, as shown in FIG. 6, a liquid containing additional abrasive grains is supplied along the direction of movement of the end surface of the glass substrate in contact with the lump of polishing fluid. As the liquid, for example, water can be used.

The supply timing of the liquid containing the additional abrasive grains is not particularly limited. For example, the liquid may be supplied at any timing during the end surface polishing process, or after the polishing of the glass substrate is finished, the next glass is supplied. It may be supplied until the polishing of the substrate is started, or may be supplied at a timing between lots divided by a predetermined time or a predetermined number of glass substrates. Further, the supply may be continued without specifying a specific timing.
In addition to the abrasive grains, magnetic fine particles or a magnetic functional fluid may be added to the liquid supplied during the end face polishing of the glass substrate G. Since the magnetic fine particles are gradually reduced by the polishing process, a decrease in the processing rate can be suppressed from a long-term viewpoint. However, since the magnetic fine particles are much less likely to decrease than the abrasive grains, supplying the magnetic fine particles may gradually increase the amount of the magnetic fine particles contained in the polishing fluid during end face polishing. is there. In this case, magnetic fine particles that cannot be held in the magnetic field may scatter around the polishing apparatus and cause the substrate surface to become dirty. Therefore, it is necessary to adjust so that the supply amount of the magnetic fine particles and the magnetic functional fluid does not become excessive.

  It is preferable that the temperature of the polishing fluid supplied during the end surface polishing process, the abrasive grains, or the liquid containing the abrasive grains is room temperature or lower. Specifically, it is 25 degrees or less, more preferably 20 degrees or less. In the end surface polishing process of this embodiment, frictional heat is generated to move the glass substrate G relative to the lump of polishing fluid across the magnetic field lines formed by the magnetic field generating means. The amount of moisture in the inside decreases, and the lubricity in the processed part deteriorates, which causes a minute scratch on the surface of the processed part. Therefore, by setting the temperature of the polishing fluid supplied during polishing to room temperature or lower, generation of the frictional heat can be suppressed, and the polishing quality of the workpiece can be maintained high.

Hereinafter, modifications of the first embodiment will be described.
[Modification 1]
Although the polishing of the outer peripheral end surface of the glass substrate G has been described with reference to FIGS. 3 to 6, the inner peripheral end surface of the glass substrate can also be polished by the same method. Modification 1 (not shown) is an example in which the inner peripheral end face is polished simultaneously with the polishing of the outer peripheral end face of the glass substrate G.
In Modification 1, a polishing apparatus (not shown) having a configuration similar to that in FIG. 3 is disposed in the vicinity of the inner peripheral end surface of the glass substrate G, and a magnetic field is generated by a pair of N-pole and S-pole magnets. . By holding the polishing fluid by this magnetic field, a lump of polishing fluid is formed. By relatively moving the lump and the inner peripheral end face of the glass substrate G in contact with each other, the inner peripheral end face of the glass substrate G is polished. At this time, the additional polishing fluid is supplied toward a position where the lump of polishing fluid held in the magnetic field and the inner peripheral end of the glass substrate G are in contact with each other.

That is, the magnetic field generating means of Modification 1 is provided such that the magnets 12 and 14 shown in FIGS. A pair of magnets (N pole and S pole) are provided on the outer peripheral side means for generating a magnetic field, and the inner peripheral side of the glass substrate G (that is, the inner hole of the glass substrate G). Inner peripheral means for generating a magnetic field so that the inner peripheral magnetic field lines) travel. The polishing of the end face is performed by holding the lump of polishing fluid by the magnetic field formed by each of the inner peripheral means and the outer peripheral means, and bringing the inner peripheral end face and the outer peripheral end face of the glass substrate G into contact with the polishing fluid lump. Both the inner peripheral end face and the outer peripheral end face are polished simultaneously by relative movement in this state. Therefore, in the first modification, the outer peripheral end face of the glass substrate G shown in FIGS. 3 and 4 can be polished and simultaneously the inner peripheral end face can be polished, and efficient end face polishing can be realized.
It is not essential to polish both the inner peripheral end face and the outer peripheral end face at the same time. That is, it is sufficient that at least one of the inner peripheral means and the outer peripheral means is provided. Further, even when both the inner peripheral means and the outer peripheral means are provided, both the inner peripheral end face and the outer peripheral end face are not polished at the same time, and the inner peripheral end face and the outer peripheral end face are polished in order. Good.

[Modification 2]
FIG. 7 is a diagram showing a second modification example of polishing of the outer peripheral end face of the glass substrate G. FIG. Modification 2 is an example in which the inner peripheral end faces of a plurality of glass substrates are polished together instead of a single glass substrate.
7 includes N pole magnets 121, 122, 123, 124,..., S pole magnets 140, 141, 142, 143,... And spacers 161, 162, 163,. . Each of the N pole magnets, each S pole magnet, and each spacer has the same configuration as the magnet 12, the magnet 14, and the spacer 16 of FIG.
That is, in the polishing apparatus 10A, the N pole end face of the magnet and the adjacent S pole end face are arranged in a stacked manner so as to face each other with a predetermined distance therebetween. In the polishing apparatus 10A, a magnetic field is formed in which magnetic lines of force are directed from an N-pole magnet facing each other through a spacer to an S-pole magnet. That is, in the thickness direction of the glass substrate G, a plurality of pairs of magnets arranged in a state of being separated so that the N-pole surface and the S-pole surface face each other are used as the magnetic field generating means. For example, a magnetic field in which magnetic lines of force are directed from the magnet 121 to the magnet 141 is formed. The lump F of the polishing fluid is held by the magnetic field at the periphery of each of the spacers 161, 162, 163,. During end face polishing, the polishing apparatus 10A is rotated as shown in FIG. 7 using a drive motor (not shown).

  The plurality of glass substrates G are integrated as a laminate by an adhesive or the like with spacers 151, 152, 153, 154,. Here, any adhesive may be used as the adhesive used to form the laminated body as long as the main surfaces of the plurality of glass substrates G can be bonded to the spacer or peeled from the spacer. For example, since an ultraviolet curable resin adhesive is easily solidified by irradiation with ultraviolet rays having a predetermined wavelength, the bonding operation is easy. Moreover, what can peel easily several glass substrate G adhere | attached with warm water or the organic solvent as an ultraviolet curable resin is preferable. As the adhesive, in addition to the UV curable resin adhesive, wax, photo curable resin, visible light curable resin, and the like can be used. Since the wax softens at a predetermined temperature and becomes liquid and becomes solid at room temperature, the bonding and peeling operations of the plurality of glass substrates G are easy. Instead of the adhesive, a spacer may be sandwiched and pasted. When sticking a spacer between a plurality of glass substrates G instead of an adhesive, a thin spacer such as a resin material, a fiber material, a rubber material, a metal material, or a ceramic material can be used. During end face polishing, the laminated body including a plurality of glass substrates G is held by a rotating body (not shown) and rotated as shown in FIG. 7 using a driving motor (not shown).

  The outer peripheral end face of each glass substrate G included in the laminate is brought into contact with the polishing fluid lump F, whereby the polishing fluid lump F and the outer peripheral end faces of the plurality of glass substrates G are moved relative to each other, whereby a plurality of glasses is obtained. The outer peripheral end face of the substrate G can be polished simultaneously. That is, since the outer peripheral end surfaces of a plurality of glass substrates can be polished at the same time, the processing rate can be made higher than before and the polishing can be performed efficiently.

  In addition, the spacer provided between the magnets is adjusted so that the intervals between the glass substrates G and the lumps of the polishing fluid lumps coincide with each other and the outer peripheral end surfaces of the glass substrates G are simultaneously in contact with the lumps of lapping fluids F. By doing so, it is preferable to adjust the formation position of the lump F of the polishing fluid. In consideration of the case where the outer peripheral end faces of the plurality of glass substrates G do not contact with each of the lumps F of the polishing fluid at the same time, the laminate of the plurality of magnets and the glass substrate G is in the direction of lamination of the laminate during polishing. It is preferable to swing relatively. By swinging, each of the lumps F of polishing fluid can be contacted without any deviation during polishing, and the outer peripheral end surfaces of the plurality of glass substrates G can be polished uniformly. This swinging is not only used for polishing the end face of the laminated body of glass substrates of the second modification, but can also be applied to the case where the end face of one glass substrate as shown in FIG. 4 is polished.

  The end face polishing process of the second modification is also performed while supplying a liquid containing abrasive grains from the outside during polishing. As a result, the abrasive grains lost during the polishing process can be supplemented, and a reduction in the chamfered surface processing rate can be suppressed when end face polishing is performed continuously. In the example shown in FIG. 7, the additional polishing fluid is supplied from the nozzle of the supply device 30 </ b> A toward a position where the polishing fluid lump F held in the magnetic field and the outer peripheral end of the glass substrate G contact each other. Since the liquid containing the abrasive grains falls from the upper side to the lower side, the liquid is supplied to a plurality of lumps F of the polishing fluid that are in contact with the outer peripheral ends of the glass substrates. Although not shown, as shown in FIG. 6, the abrasive grains are included in the lateral direction from each of the plurality of nozzles toward the position where the lump F of each polishing fluid and the outer peripheral end of the glass substrate G contact each other. A liquid may be supplied.

  Although FIG. 7 illustrates the case where the outer peripheral end faces of a plurality of glass substrates G integrated as a laminate are illustrated, the inner peripheral end faces of the plurality of glass substrates G may be similarly polished. Moreover, you may grind | polish the outer peripheral end surface and inner peripheral end surface of the several glass substrate G integrated as a laminated body simultaneously.

[Modification 3]
FIG. 8 is a diagram showing a third modification of the end surface polishing. In Modification 3, the same polishing apparatus 10 as in FIG. 4 is used, but both the polishing apparatus 10 and the glass substrate G to be polished are immersed in a bath 90 filled with a liquid containing polishing abrasive grains. Then, the end surface of the glass substrate G is polished. Although the density | concentration of the abrasive grain in a tank may be the same value as the value demonstrated in embodiment, it can be 1-50 wt%, for example. For example, water can be used as the liquid.
In the tank 90, as in FIG. 4, a magnetic field is formed so that the magnetic lines of force from the magnet 12 toward the magnet 14 are advanced, and the polishing fluid around the magnetic field is held as a lump F by the magnetic field. The outer peripheral end of the glass substrate G is polished by repeatedly bringing the outer peripheral end of the glass substrate G into contact with the polishing fluid mass F and moving the glass substrate G and the polishing fluid mass F relative to each other. At this time, as described above, in a part of the region (region A2 in FIG. 5), the end of the glass substrate crosses the magnetic flux lines, so that the arrangement of the magnetic fine particles in the polishing fluid collapses, thereby causing a magnetic field. Since the holding power of the abrasive grains is locally reduced, the abrasive grains are easily released to the outside. However, in this modified example, since polishing is performed in a tank 90 filled with a liquid containing polishing abrasive grains, the released polishing abrasive grains are supplied by surrounding polishing abrasive grains in the tank and polished continuously. The situation in which the concentration of the abrasive grains decreases when the above is performed is avoided. Therefore, the processing rate does not decrease with time.
FIG. 8 illustrates the case where the outer peripheral end surface of one glass substrate G is ground in the polishing fluid bath 90, but is not limited thereto. The inner peripheral end face of the glass substrate G may be polished in the polishing fluid bath 90, or the end faces of the laminate of the plurality of glass substrates G may be polished as shown in the second modification.

[Example]
In order to confirm the effect of the present invention, end face polishing of the produced glass substrate was performed.
The produced glass substrate has an outer diameter of 65 mm and a thickness of 0.8 mm. In the shape processing, a chamfer of 0.15 mm in the thickness direction of the glass substrate is inclined at 45 degrees with respect to the main surface. gave.

(Comparative example)
As shown in FIG. 4, the outer peripheral edge of a glass substrate for a 2.5 inch type magnetic disk was inserted into a polishing apparatus in which a pair of magnets were spaced apart by a stainless steel spacer. The dimensions of the magnet were 19 mm in diameter and 15 mm in thickness. Then, a polishing fluid was applied between the magnets to hold the mass of the magnet slurry in the magnetic field formed by the magnets, and the outer peripheral end surface of the glass substrate was polished. The end surface of the glass substrate and the polishing apparatus were rotated so as to be opposite to each other, and the number of rotations was set to 700 rpm. 100 glass substrates were polished, and the processing time for each one was 3 minutes.
The polishing fluid used for polishing the outer peripheral end surface of the glass substrate is 3 [g / cm ³ ] of fine particles of Fe (iron) having an average particle diameter (D50) of 2 μm dispersed in non-magnetic oil (silicon oil). In addition, abrasive grains in which cerium oxide having an average particle diameter of 2 μm was dispersed were used. The concentration of cerium oxide in the polishing fluid was included to be 5 [vol%]. A permanent magnet having a magnetic flux density of 0.5 [Tesla] was used as the magnet.

Example 1
In addition to the polishing conditions of the comparative example, polishing was performed while supplying a liquid containing abrasive grains. Specifically, as shown in FIG. 6, the polishing of the outer peripheral end surface of one glass substrate is finished with a liquid containing abrasive grains along the moving direction of the end surface of the glass substrate in contact with the lump of polishing fluid. Supplied every time. The liquid was water. As in the comparative example, 100 glass substrates were polished, and the processing time for each sheet was 3 minutes.

(Evaluation of Comparative Example and Example 1)
As a result of measuring the processing rate of the first glass substrate and the 100th glass substrate with respect to the chamfered surface of the outer peripheral end surface of the glass substrate after end face polishing in Comparative Example and Example 1, the results are as shown in Table 1. It was. In Table 1, the reduction rate of the processing rate is a value calculated by the following equation (1).
Reduction rate (%) of processing rate = 100− (processing rate of the 100th glass substrate) / (processing rate of the first glass substrate) × 100 (1)

  As shown in Table 1, in Example 1, when the glass substrate was continuously polished, it was confirmed that the reduction in the processing rate was greatly suppressed as compared with the comparative example. Although not shown in Table 1, the rate of reduction of the processing rate on the side wall surface was 2% or less in both the comparative example and Example 1, which was a level that does not cause a problem.

(Example 2)
The outer peripheral end face of the glass substrate was polished in the same manner as in the comparative example except that the liquid containing the abrasive grains was continuously supplied to the lump of polishing fluid continuously during the polishing process. At this time, the liquid was dropped from above onto the lump of polishing fluid immediately before reaching the polishing portion (processing point).
As a result, the reduction rate of the processing rate on the chamfered surface of the glass substrate was 5%, and a better result than Example 1 was obtained. In addition, the reduction rate of the processing rate in the side wall surface of a glass substrate was 2% or less similarly to Example 1.

(Example 3)
As shown in FIG. 8, the outer peripheral end face of the glass substrate was polished in a state where the glass substrate to be polished was immersed in a tank filled with a liquid containing abrasive grains. The liquid in the tank was water, and the abrasive grain concentration was 20 wt%. During the polishing, the liquid was not supplied into the tank.
As a result, the reduction rate of the processing rate on the chamfered surface of the glass substrate was 0%, and a result better than that of Example 2 was obtained.

(Second Embodiment)
Hereinafter, a method for manufacturing a magnetic disk substrate will be described as a second embodiment of the method for manufacturing a nonmagnetic substrate of the present invention. Although the case where a glass substrate is used as the magnetic disk substrate as in the first embodiment will be described, the present invention is not limited thereto, and an aluminum synthetic substrate may be used.
In this embodiment, the entire processing flow of the magnetic disk glass substrate, the manufacturing method of the magnetic disk glass substrate, and the end surface polishing method using the magnetic field generating means and the polishing fluid (in association with FIGS. 3 and 4). The content described is the same as in the first embodiment. The following description will focus on the details of the end surface polishing process different from the first embodiment.

In the second embodiment, in the end surface polishing of a glass substrate using a polishing fluid, when the end surfaces of a plurality of glass substrates that are workpieces are continuously polished by a single wafer processing, the processing rate of the chamfered surface is increased. A process of correcting the shape of the lump of the polishing fluid is performed so as not to greatly decrease. Here, the reason why the processing rate of the chamfered surface is lowered when the shape of the polishing fluid is not corrected in the end surface polishing of the glass substrate will be described with reference to FIG.
9, in the state S1, which is the initial state of the end surface polishing process, the lump F of the polishing fluid is stably held by the magnetic field formed by the magnets 12 and 14. Immediately after starting the contact of the glass substrate G with the lump F of the polishing fluid, the side wall surface and the chamfered surface constituting the outer peripheral end surface of the glass substrate G are pressed from the lump F with a constant pressing force, Both chamfered surfaces are in a high processing rate.
However, when end face polishing is continuously performed on a plurality of glass substrates by single-wafer processing, the processing rate of the side wall surface hardly decreases, but the processing rate of the chamfered surface greatly decreases. That is, the side wall surface of the outer peripheral end surface of the glass substrate is polished by the lump F of the polishing fluid in the region A1 where the glass substrate G does not cross the lines of magnetic force in plan view. The lump F of the polishing fluid in the region A1 has a high holding force of the lump F due to the magnetic field because the lines of magnetic force are not cut off, and the polishing is performed stably by the abrasive grains, so that the polishing processing rate is high. On the other hand, the chamfered surface of the outer peripheral end surface of the glass substrate is polished by the lump F of the polishing fluid in the region A2 where the glass substrate G crosses the lines of magnetic force in plan view. The lump F of the polishing fluid in this area A2 has a relatively weak holding force due to the magnetic field. Therefore, when end face polishing is continuously performed on a plurality of glass substrates G by a single wafer processing, the lump F of the polishing fluid collapses and deforms (plastic deformation) in the region A2, as shown in the state S2 of FIG. ), And the pressing force against the chamfered surface on the outer peripheral side of the glass substrate G tends to decrease. When the pressing force with respect to the chamfered surface of the glass substrate G is lowered, it is difficult to stably perform polishing by the abrasive grains, so that the processing rate of chamfered surface polishing is reduced.

Therefore, in the end surface polishing process of the present embodiment, the shape of the lump F of the polishing fluid deformed by contact with the glass substrate G is corrected so that the pressing force on the glass substrate G is maintained constant.
Hereinafter, a method for correcting a lump of polishing fluid using a shape correcting device in the end surface polishing process of the present embodiment will be described with reference to FIGS. 10 and 11. FIG. 10 is a diagram illustrating a configuration example when the shape of the polishing fluid is corrected using the shape correcting device. FIG. 11 is a diagram for explaining the shape correction processing of the polishing fluid using the shape correction device.
In FIG. 10, the shape correcting device 20 includes jigs 21U, 21L, and 22 that are made of a non-magnetic material and are arcuate in plan view, and drive mechanisms (not shown) that drive the jigs. A driving mechanism (not shown) drives the jig 21U and the jig 21L in the horizontal direction and the vertical direction so that the jig 21U and the jig 21L can move on the surfaces of the magnet 12 and the magnet 14, respectively. The driving mechanism drives the jig 22 in the horizontal direction so that the jig 22 can be inserted into the space between the magnet 12 and the magnet 14. The length of the jig 22 in the thickness direction of the glass substrate is preferably set to be the same as or slightly lower than the distance between the magnet 12 and the magnet 14. Note that the jig 21U and the jig 21L may not be provided in the shape correction device 20 depending on the degree of shape correction of the polishing fluid.

In FIG. 11, in a series of processes (steps S <b> 1 to S <b> 3) in which the shape correcting device 20 corrects the shape of the lump F of the polishing fluid, the positional relationship between each jig of the shape correcting device 20 and the magnets 12 and 14 is It is shown by a figure and a plan view. In the example shown in FIG. 11, it is assumed that the jig 22 has already been positioned in the vertical direction.
First, in step S1, the jigs 21U and 21L are driven in the horizontal direction, and the jigs contact the side surfaces of the magnets 12 and 14, respectively. Next, in step S2, the jig 21U is driven downward, and the jig 21L is driven upward. As a result, the polishing fluid sticking out from the side surfaces of the magnets 12 and 14 (that is, a part of the deformed polishing fluid mass F) is pressed and moved to a position between the magnets 12 and 14 in a side view. Be made. Finally, in step S3, the jig 22 is driven in the horizontal direction, and the polishing fluid moved in step S2 or the polishing fluid moved to the peripheral edge of each magnet due to deformation of the lump F is pressed by the jig 22. Is moved toward the center of the magnet. Through the above steps S1 to S3, the shape of the deformed lump F of the polishing fluid is corrected so as to keep the pressing force against the glass substrate constant.
When there is no polishing fluid protruding on the side surfaces of the magnets 12 and 14, the jig 21U and the jig 21L may not be used.

As described above, in this embodiment, the shape correcting device 20 is used to correct the shape of the lump F of the polishing fluid deformed by contact with the glass substrate so as to return to the original shape. In other words, the shape of the polishing fluid mass F is changed by bringing the jig into contact with the polishing fluid mass F. Thereby, the pressing force on the glass substrate is kept constant.

In the present embodiment, it is preferable that the jig is brought into contact with the lump F of the polishing fluid so that the tip of the jig is inserted into the lump F of the polishing fluid. For example, instead of the jig 22 shown in FIG. 10, a jig having a convex cross section at the tip is used, and the tip of the jig is inserted into the lump F of polishing fluid by driving the jig in the horizontal direction. Like that. The shape of the jig may be a rod shape, a plate shape, a flat shape, or a prism shape. That is, the cross section of the tip of the jig may be circular or elliptical, flat, or polygonal. The height of such a jig in the vertical direction (that is, the thickness direction of the glass substrate G to be polished) may be less than or equal to the gap between the magnets 12 and 14. The same applies to the jigs 21U, 21L, and 22 described above, but the material of the jig is preferably a non-magnetic and relatively hard material such as a metal such as aluminum or titanium or ceramic.
The reason why it is preferable to insert the tip of the jig into the lump of polishing fluid is as follows. That is, as shown in the state S2 of FIG. 9, the lump F of the polishing fluid collapses and deforms (plastically deforms) in the region A2, and the pressing force against the chamfered surface on the outer peripheral side of the glass substrate G decreases. It is considered that the density of the magnetic fine particles is uneven within the fluid mass. That is, in the area A1 in FIG. 9, the magnetic fine particles are dense due to the substrate being pushed in, and in the area A2, the density is low, thereby reducing the holding power of the abrasive grains in the area A2. It is thought that. Therefore, by inserting the tip of the jig into the lump of polishing fluid and moving the magnetic fine particles pushed toward the back, the rearrangement by the magnetic field of the magnetic fine particles inside the polishing fluid is promoted, There is no density deviation of the magnetic fine particles before processing. Therefore, it is possible to further suppress a decrease in the chamfered surface processing rate.

  The timing for correcting the shape of the lump of the polishing fluid may be any time as long as it is during the end face polishing process. As shown in FIG. 10, with the polishing device 10 as a reference, the shape correcting device 20 is arranged on the opposite side of the glass substrate G that is a workpiece, so that the polishing fluid lump can be obtained while polishing the end surface of the glass substrate G. Shape correction can be performed. Further, the shape correction may be performed after the end surface polishing of the glass substrate is completed until the end surface polishing of the next glass substrate is started, or timing between lots divided by a predetermined time or a predetermined number of glass substrates. The shape may be corrected by.

Next, as another method of correcting the shape of the polishing fluid lump, a method of supplying additional polishing fluid to the deformed polishing fluid lump will be described with reference to FIG.
FIG. 12 shows an example in which the polishing fluid is supplied to the polishing apparatus 10 from the nozzle of the supply apparatus 30 in a plan view. In the example shown in FIG. 12, the additional polishing fluid is supplied toward a position where the lump of polishing fluid held in the magnetic field and the outer peripheral end of the glass substrate G are in contact with each other. More preferably, it is supplied to a lump of polishing fluid at a position after contact with the part. Also, and more preferably additional polishing fluid Ru along the direction of movement of the end face of the glass substrate in contact with the mass of the polishing fluid. This additional polishing fluid is newly held in the magnetic field as a lump, and as a result, the shape of the lump of polishing fluid is modified so as to maintain a constant pressing force on the glass substrate.

  The supply timing of the additional polishing fluid is not particularly limited. For example, the additional polishing fluid may be supplied at an appropriate time during the end surface polishing process, or the end surface polishing of the next glass substrate starts after the end surface polishing of the glass substrate is completed. It may be supplied until it is done, or may be supplied at a predetermined time or at a timing between lots divided by a predetermined number of glass substrates. Further, the supply may be continued without specifying a specific timing.

  The temperature of the polishing fluid supplied during the end surface polishing treatment is preferably room temperature or lower. In the end surface polishing process of the present embodiment, frictional heat is generated to move the glass substrate G relative to the lump of polishing fluid so as to cross the magnetic field lines formed by the magnetic field generating means. This frictional heat is generated by the polishing fluid. As a result, the polishing processing rate is lowered. Therefore, by setting the temperature of the polishing fluid supplied during polishing to room temperature or less, generation of the frictional heat can be suppressed and the polishing processing rate can be kept high.

Hereinafter, modifications of the second embodiment will be described.
[Modification 1]
Although the grinding | polishing of the outer peripheral end surface of the glass substrate G was demonstrated with reference to FIGS. 9-12, it can grind | polish also about the inner peripheral end surface of a glass substrate by the same method. Modification 1 (not shown) is an example of polishing the inner peripheral end face simultaneously with the polishing of the outer peripheral end face of the glass substrate G, and is the same polishing method as the first modification of the first embodiment. The explanation is omitted.

  In the first modification of the second embodiment, for example, the additional polishing fluid is directed toward the position where the lump of polishing fluid held in the magnetic field and the inner peripheral end of the glass substrate G are in contact with each other by the supply device. By supplying, the shape of the lump of the polishing fluid for polishing the inner peripheral end face is corrected so as to keep the pressing force against the glass substrate constant. For the outer peripheral end face polishing, the shape of the polishing fluid lump for polishing the outer peripheral end face is obtained by correcting the shape of the polishing fluid lump by the shape correcting device described above or by supplying an additional polishing fluid. Then, the pressing force on the glass substrate is corrected to be kept constant. Therefore, in this modification, it is possible to suppress a decrease in the processing rate of the inner peripheral side chamfered surface and the outer peripheral side chamfered surface while simultaneously polishing both the inner peripheral end surface and the outer peripheral end surface.

[Modification 2]
FIG. 13 is a diagram illustrating a second modification example of polishing of the outer peripheral end surface of the glass substrate G. FIG. Modification 2 is an example in which the outer peripheral end surfaces of a plurality of glass substrates are polished together instead of a single glass substrate.
A polishing apparatus 10A shown in FIG. 13 includes N-pole magnets 121, 122, 123, 124,..., S-pole magnets 140, 141, 142, 143,... And spacers 161, 162, 163,. . Each of the N pole magnets, each S pole magnet, and each spacer has the same configuration as the magnet 12, the magnet 14, and the spacer 16 of FIG.
That is, in the polishing apparatus 10A, the N pole end face of the magnet and the adjacent S pole end face are arranged in a stacked manner so as to face each other with a predetermined distance therebetween. In the polishing apparatus 10A, a magnetic field is formed in which magnetic lines of force are directed from an N-pole magnet facing each other through a spacer to an S-pole magnet. That is, in the thickness direction of the glass substrate G, a plurality of pairs of magnets arranged in a state of being separated so that the N-pole surface and the S-pole surface face each other are used as the magnetic field generating means. For example, a magnetic field in which magnetic lines of force are directed from the magnet 121 to the magnet 141 is formed. The lump F of the polishing fluid is held by the magnetic field at the periphery of each of the spacers 161, 162, 163,. During end face polishing, the polishing apparatus 10A is rotated as shown in FIG. 13 using a drive motor (not shown).

  The plurality of glass substrates G are integrated as a laminate by an adhesive or the like with spacers 151, 152, 153, 154,. Here, the adhesive used for forming the laminate may be the same as that described in the second modification of the first embodiment. During end face polishing, the laminated body including a plurality of glass substrates G is held by a rotating body (not shown) and rotated as shown in FIG. 13 using a driving motor (not shown).

The outer peripheral end face of each glass substrate G included in the laminate is brought into contact with the polishing fluid lump F, whereby the polishing fluid lump F and the outer peripheral end faces of the plurality of glass substrates G are moved relative to each other, whereby a plurality of glasses is obtained. The outer peripheral end face of the substrate G can be polished simultaneously. That is, since the outer peripheral end surfaces of a plurality of glass substrates can be polished at the same time, the processing rate can be made higher than before and the polishing can be performed efficiently.
The technical matters described in the second modification of the first embodiment (for example, adjustment of spacers between magnets and swinging of a laminate of a plurality of magnets and a glass substrate G) are the same in this modification. Is also applicable.

  In the end face polishing process of the modified example 2, it is performed while supplying a new polishing fluid from the outside during polishing. In the example shown in FIG. 13, additional polishing fluid from each of the plurality of nozzles 301, 302, 303,... Toward the position where the lump F of each polishing fluid and the outer peripheral edge of the glass substrate G contact each other. Supplied. The additional polishing fluid is newly held in the magnetic field as a lump, and as a result, the shape of each lump F of the polishing fluid is corrected so as to keep the pressing force against each glass substrate constant. Thereby, when end surface grinding | polishing is continuously performed with respect to the laminated body of the glass substrate G, the fall of the processing rate of the chamfering surface of each glass substrate G can be suppressed.

  Although FIG. 13 illustrates the case where the outer peripheral end faces of the plurality of glass substrates G integrated as a laminate are illustrated, the inner peripheral end faces of the plurality of glass substrates G may be similarly polished. Moreover, you may grind | polish the outer peripheral end surface and inner peripheral end surface of the several glass substrate G integrated as a laminated body simultaneously.

[Example]
In order to confirm the effect of the present invention, end face polishing of the produced glass substrate was performed.
The produced glass substrate has an outer diameter of 65 mm and a thickness of 0.8 mm. In the shape processing, a chamfer of 0.15 mm in the thickness direction of the glass substrate is inclined at 45 degrees with respect to the main surface. gave.

(Comparative example)
As shown in FIG. 4, the outer peripheral edge of a glass substrate for a 2.5 inch type magnetic disk was inserted into a polishing apparatus in which a pair of magnets were spaced apart by a nonmagnetic stainless steel spacer. The dimensions of the magnet were 19 mm in diameter and 15 mm in thickness. Then, a polishing fluid was applied between the magnets to hold the mass of the magnet slurry in the magnetic field formed by the magnets, and the outer peripheral end surface of the glass substrate was polished. The end surface of the glass substrate and the polishing apparatus were rotated so as to be opposite to each other, and the number of rotations was set to 700 rpm. 100 glass substrates were polished, and the processing time for each one was 3 minutes. There was no polishing fluid protruding on the side of the magnet.
The polishing fluid used for polishing the outer peripheral end surface of the glass substrate is 3 [g / cm ³ ] of fine particles of Fe (iron) having an average particle diameter (D50) of 2 μm dispersed in non-magnetic oil (silicon oil). In addition, abrasive grains in which cerium oxide having an average particle diameter of 1.5 μm was dispersed were used. The concentration of cerium oxide in the polishing fluid was 7 [vol%]. A permanent magnet having a magnetic flux density of 0.5 [Tesla] was used as the magnet.

Example 1
As in the comparative example, 100 glass substrates were polished, and the processing time for each sheet was 3 minutes. In Example 1, polishing was performed under the same conditions as the polishing conditions of the comparative example except that the shape of the lump of deformed polishing fluid was corrected using a shape correction device every time 10 glass substrates were polished. .

(Evaluation of Comparative Example and Example 1)
As a result of measuring the processing rate of the first glass substrate and the 100th glass substrate on the chamfered surface of the outer peripheral end surface of the glass substrate after end surface polishing in Comparative Example and Example 1, the results are as shown in Table 2. It was. Here, the formula (1) described above was applied as a method of calculating the reduction rate of the processing rate. As shown in Table 2, in Example 1, when the glass substrate was continuously polished, it was confirmed that a decrease in the chamfered surface processing rate was greatly suppressed as compared with the comparative example. If the reduction rate of the processing rate is 10% or less, there is no particular problem in the manufacturing process.

(Example 2)
A glass substrate under the same conditions as in the above comparative example except that a rod-shaped aluminum jig having a convex cross section was used and the tip of the jig was inserted into a lump of polishing fluid during end face polishing. The outer peripheral end face of was ground. As a result, the reduction rate of the processing rate on the chamfered surface of the glass substrate was 1%, which was better than that of Example 1.

(Example 3)
Instead of using the shape correcting device, a polishing fluid was added during the polishing process to polish the outer peripheral end surface of the glass substrate. In this case, the reduction rate of the processing rate on the chamfered surface of the glass substrate was 6%.

Example 4
In addition to the conditions of Example 1, polishing was performed while supplying a liquid containing abrasive grains. Specifically, as shown in FIG. 6, the polishing of the outer peripheral end surface of one glass substrate is finished with a liquid containing abrasive grains along the moving direction of the end surface of the glass substrate in contact with the lump of polishing fluid. Supplied every time. The liquid was water.
In this case, the reduction rate of the processing rate on the chamfered surface of the glass substrate was 0%, which was even better than Example 2.

Furthermore, the curvature radius of the shape of the part between a side wall surface and a chamfering surface was measured about 100 glass substrates of grinding | polishing object.
Here, with reference to FIG. 14, a method for obtaining the curvature radius of the shape of the portion between the side wall surface and the chamfered surface will be described. In FIG. 14, R is the radius of a circle C2 that forms the curvature of the shape of the portion between the side wall surface 1t and the chamfered surface 1c, and is the curvature radius of the shape of the portion. The curvature radius R can be determined as follows, for example. First, let P1 be the intersection of an imaginary line L1 extending the straight line portion of the chamfered surface 1c and a virtual line L2 extending the straight line portion of the side wall surface 1t. Next, an imaginary line L3 passing through the intersection point P1 and extending perpendicularly to the straight line portion of the chamfered surface 1c is set. Next, an intersection between the portion between the side wall surface 1t and the chamfered surface 1c and the virtual line L3 is defined as P2. In the cross section of the glass substrate G, a circle C1 having a predetermined radius (for example, 50 μm) around the intersection P2 is set. Moreover, let two intersections of the part between the side wall surface 1t and the chamfering surface 1c and the outer periphery of the circle C1 be P3 and P4, respectively. Further, a circle C2 passing through each of the three intersections P2, P3, P4 is set. Then, by determining the radius of the circle C2, the radius of curvature R of the shape of the portion between the side wall surface 1t and the chamfered surface 1c is determined.
Note that the radius of curvature of the shape of the portion between the side wall surface 1t and the other chamfered surface 1c (not shown in FIG. 14) can also be determined in the same manner as described above.

  The radius of curvature is measured for each of the 100 glass substrates (the average value for each arbitrary point on the circumference on both sides), and the variation in 100 sheets (here, defined as the difference between the maximum value and the minimum value). As a result of calculation, the ratio of the variation size of Example 4 to the variation size of Example 1 (Example 4 / Example 1) was 0.5, which was significantly reduced. This is because not only the decrease in the polishing rate of the chamfered surface is suppressed but also the polishing of the portion between the side wall surface and the chamfered surface is stabilized by the synergistic effect by supplying the liquid containing abrasive grains. This is presumed to be due to this. That is, since the portion between the side wall surface and the chamfered surface is pointed, generally the shape of the portion is likely to fluctuate even by a slight change in the processing conditions, but in Example 4, the fluctuation was suppressed. I was able to confirm.

  As mentioned above, although the manufacturing method of the nonmagnetic board | substrate of this invention was demonstrated in detail, this invention is not limited to the said embodiment and modification, In the range which does not deviate from the main point of this invention, various improvement and a change are carried out. Of course, it is good. For example, although the manufacturing method of the glass substrate for magnetic disks was demonstrated as one Embodiment of the manufacturing method of the nonmagnetic board | substrate of this invention, the processing object should just be a nonmagnetic board | substrate and other materials, such as an aluminum alloy board | substrate, It can also be applied to non-magnetic substrates.

DESCRIPTION OF SYMBOLS 1 ... Magnetic disk glass substrate G ... Glass substrate 10, 10A ... Polishing apparatus 5a ... Magnetic fine particle 5b ... Polishing abrasive grain 12, 14, 121-124, 140-143 ... Magnet 16, 151-154, 161-163 ... Spacer F ... Mass M ... Magnetic field line 20 ... Shape correction device 21U, 21L, 22 ... Jig 30, 30A ... Supply device 90 ... Tank

Claims (10)

A method for producing a nonmagnetic substrate, comprising an end surface polishing treatment for polishing an end surface of a plate-like nonmagnetic substrate having a side wall surface and a main surface,
The end surface polishing treatment uses the magnetic field generating means to form a magnetic field so that a magnetic line of force advances in the thickness direction of the substrate, and to hold the magnetic functional fluid containing abrasive grains in the magnetic field. A process of polishing the end face of the substrate by forming a fluid mass, bringing the end surface of the substrate into contact with the mass of the magnetic functional fluid, and moving the substrate and the mass of the magnetic functional fluid relative to each other. And
Manufacturing of a non-magnetic substrate characterized by correcting the shape of the mass of the magnetic functional fluid deformed by contact with the substrate so that the pressing force against the substrate is kept constant by contacting the jig Method. A method for producing a nonmagnetic substrate, comprising an end surface polishing treatment for polishing an end surface of a plate-like nonmagnetic substrate having a side wall surface and a main surface,
The end surface polishing treatment uses the magnetic field generating means to form a magnetic field so that a magnetic line of force advances in the thickness direction of the substrate, and to hold the magnetic functional fluid containing abrasive grains in the magnetic field. A process of polishing the end face of the substrate by forming a fluid mass, bringing the end surface of the substrate into contact with the mass of the magnetic functional fluid, and moving the substrate and the mass of the magnetic functional fluid relative to each other. And
A shape of the mass of the magnetic functional fluid is corrected by moving the magnetic functional fluid by bringing a jig into contact with the mass of the magnetic functional fluid deformed by contact with the substrate. A method of manufacturing a nonmagnetic substrate. A method for producing a nonmagnetic substrate, comprising an end surface polishing treatment for polishing an end surface of a plate-like nonmagnetic substrate having a side wall surface and a main surface,
The end surface polishing treatment uses the magnetic field generating means to form a magnetic field so that a magnetic line of force advances in the thickness direction of the substrate, and to hold the magnetic functional fluid containing abrasive grains in the magnetic field. A process of polishing the end face of the substrate by forming a fluid mass, bringing the end surface of the substrate into contact with the mass of the magnetic functional fluid, and moving the substrate and the mass of the magnetic functional fluid relative to each other. And
A method of manufacturing a non-magnetic substrate, wherein the shape of the mass of the magnetic functional fluid deformed by contacting with the substrate is corrected so as to return to the original shape by contacting a jig. A method for producing a nonmagnetic substrate, comprising an end surface polishing treatment for polishing an end surface of a plate-like nonmagnetic substrate having a side wall surface and a main surface,
The end surface polishing treatment uses the magnetic field generating means to form a magnetic field so that a magnetic line of force advances in the thickness direction of the substrate, and to hold the magnetic functional fluid containing abrasive grains in the magnetic field. A process of polishing the end face of the substrate by forming a fluid mass, bringing the end surface of the substrate into contact with the mass of the magnetic functional fluid, and moving the substrate and the mass of the magnetic functional fluid relative to each other. And
A method of manufacturing a non-magnetic substrate, wherein a shape of the mass of the magnetic functional fluid is changed by bringing a jig into contact with the mass of the magnetic functional fluid.   The tip of the jig is inserted into the mass of the magnetic functional fluid, and the jig is brought into contact with the mass of the magnetic functional fluid. The manufacturing method of the nonmagnetic board | substrate as described in a term.   The nonmagnetic property according to any one of claims 1 to 5, wherein a shape of the magnetic functional fluid is corrected by supplying an additional mass of the magnetic functional fluid and contacting a jig. A method for manufacturing a substrate.   The magnetic field generation means includes a pair of magnets arranged in a state in which the N-pole surface and the S-pole surface are spaced apart from each other in the thickness direction of the substrate. A method for producing a non-magnetic substrate according to item 1.   The method of manufacturing a nonmagnetic substrate according to claim 7, wherein a spacer made of a nonmagnetic material is provided between the N pole surface and the S pole surface of the pair of magnets. The substrate has a disk shape having a circular inner hole,
The magnetic field generating means is provided in the inner hole of the substrate and generates a magnetic field so that an inner peripheral magnetic field line advances in the thickness direction of the substrate around an inner peripheral end surface which is a side wall surface of the inner hole. Inner peripheral means for forming and / or an outer peripheral side which is provided on the outer peripheral side of the substrate and forms a magnetic field around the outer peripheral end surface of the substrate so that outer peripheral magnetic lines of force advance in the thickness direction of the substrate Means,
The inner peripheral end face and / or the outer peripheral end face of the substrate is held in a state where the mass of the magnetic functional fluid is held in a magnetic field formed by each of the inner peripheral means and / or the outer peripheral means. The method for manufacturing a nonmagnetic substrate according to claim 1, wherein the inner peripheral end face and / or the outer peripheral end face is polished.   The non-magnetic substrate manufacturing method according to any one of claims 1 to 9, wherein the abrasive grains are supplied to the lump of the magnetic functional fluid during an end surface polishing process of the substrate. Method.

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