JP5312911B2 - Manufacturing method of glass substrate for magnetic disk and manufacturing method of magnetic disk - Google Patents

Description

  The present invention relates to a method for manufacturing a glass substrate for a magnetic disk used in a magnetic disk device such as a hard disk drive (hereinafter referred to as “HDD”) and a method for manufacturing a magnetic disk using the glass substrate for a magnetic disk.

  There is a magnetic disk as a magnetic recording medium mounted on a magnetic disk device such as an HDD. A magnetic disk is manufactured by laminating a magnetic layer or a protective layer on a substrate, a glass substrate, or a ceramic substrate on which a NiP film is deposited on a metal plate made of an aluminum-magnesium alloy or the like. Conventionally, an aluminum alloy substrate has been widely used as a substrate for a magnetic disk. However, with recent downsizing, thinning, and high-density recording of magnetic disks, surface flatness and A glass substrate having excellent strength with a thin plate has been used. Such a glass substrate for a magnetic disk is excellent in strength as compared with an aluminum alloy substrate, and thus is suitable for high-speed rotation of a magnetic disk device. Also, since a smooth and flat surface can be obtained, the flying height of the magnetic head is reduced, which is suitable for improving the S / N ratio and increasing the recording density.

  In general, such a glass substrate for a magnetic disk includes a cutting step; a shape processing step; a roughening step (first grinding step); a fine lapping step (second grinding step); an end surface polishing step; a main surface polishing step first. And the second polishing step); manufactured through a chemical strengthening step and the like.

  In the main surface polishing step (first and second polishing steps) described above, it is intended to obtain the desired surface roughness and outer peripheral edge shape of the glass substrate and to flatten the undulation generated in the glass substrate. . In this main surface polishing step, a glass substrate is sandwiched between an upper surface plate and a lower surface plate of a polishing apparatus, and polishing is performed using loose abrasive grains (slurry) while being set on a carrier and rotated in the reverse direction. . In this case, as the free abrasive grains (slurry), abrasive grains having a particle size corresponding to a predetermined surface quality of the glass substrate are used. For example, in the first polishing step, polishing is performed using cerium oxide abrasive grains, and in the second polishing step, polishing is performed using silica abrasive grains (see, for example, Patent Document 1).

It is known that the surface roughness of the glass substrate surface after polishing is better as the particle size of the free abrasive grains (slurry) used for polishing is smaller and the hardness of the polishing pad is lower. For this reason, in the second polishing step, a glass substrate having a low surface roughness is prepared by polishing using fine silica particles (average particle diameter of 10 nm to 100 nm) and a suede pad having a low hardness. Had gone.
JP 2001-191247 A

  However, as described above, when polishing is performed using fine loose abrasive grains (slurry) and a polishing pad with low hardness, a good surface roughness can be obtained in the glass substrate, but the edge shape is deteriorated. There is a problem. That is, when a polishing pad with low hardness is used, the polishing pad sinks to the carrier side during polishing, and the load on the end of the glass substrate becomes larger than that of the main surface. As a result, problems such as roll-off may occur in the end shape of the glass substrate.

  As a measure for suppressing such sinking of the polishing pad, it is conceivable to increase the thickness dimension of the entire carrier with respect to the glass substrate. However, in this case, there arises a problem that the load by the polishing pad is not applied to the glass substrate, and the polishing rate is remarkably reduced. It is also conceivable to perform polishing using a polishing pad with high hardness. However, in this case, there arises a problem that the surface roughness of the polished glass substrate is deteriorated as described above.

  The present invention has been made in view of such problems, and even when polishing is performed using fine loose abrasive grains and a polishing pad with low hardness, the end portion is maintained while maintaining good surface roughness. It is an object of the present invention to provide a method of manufacturing a glass substrate for a magnetic disk and a method of manufacturing a magnetic disk that can improve the deterioration of the shape.

  The method for producing a glass substrate for a magnetic disk of the present invention is a method for producing a glass substrate for a magnetic disk comprising a polishing step of polishing a main surface of a glass substrate held in a state where a part is exposed from a carrier, The polishing pad is brought into close contact with the main surface of the glass substrate in a state where movement of the polishing pad toward the carrier side in the vicinity of the outer periphery of the glass substrate is regulated, and the main surface of the glass substrate is polished by rotating the carrier. It is characterized by that.

  According to this method, the polishing pad is brought into close contact with the main surface of the glass substrate in a state in which the movement of the polishing pad toward the carrier side in the vicinity of the outer periphery of the glass substrate is regulated. Since the main surface of the glass substrate can be polished while suppressing the sinking into the edge, even when polishing using fine loose abrasive grains and a polishing pad with low hardness, the edge while maintaining good surface roughness It becomes possible to improve the deterioration of the shape.

  In the method for manufacturing a glass substrate for a magnetic disk of the present invention, the polishing pad is moved to the carrier side by a retainer ring that is disposed in the vicinity of the outer periphery of the glass substrate and has substantially the same thickness as the glass substrate. It is preferable to regulate. In this case, the main surface of the glass substrate can be polished while suppressing the situation where the polishing pad sinks to the carrier side during polishing by a simple configuration of the retainer ring having substantially the same thickness dimension of the glass substrate. It becomes.

  In particular, in the method for manufacturing a glass substrate for a magnetic disk according to the present invention, it is preferable that the retainer ring is fixed in a holding portion of the glass substrate in the carrier, and the glass substrate is held on an inner peripheral surface of the retainer ring. . In this case, it is not necessary to dispose the retainer ring in the carrier holding portion when performing the polishing process, so that the working efficiency in the polishing process can be improved.

  In the method for manufacturing a glass substrate for a magnetic disk according to the present invention, when the polishing step is performed, the retainer ring is disposed in a holding portion of the glass substrate in the carrier, and the glass is formed on the inner peripheral surface of the retainer ring. You may make it hold | maintain a board | substrate. In this case, since the fixing work for the carrier holding portion can be omitted, the cost required for the fixing work can be reduced.

  In the method for manufacturing a glass substrate for a magnetic disk according to the present invention, a part of the carrier disposed in the vicinity of the outer periphery of the glass substrate is provided with substantially the same thickness as the glass substrate, and one of the carriers is provided. The movement of the polishing pad toward the carrier may be regulated by the portion. In this case, the main surface of the glass substrate can be polished while suppressing the situation where the polishing pad sinks to the carrier side during polishing only by the carrier, without requiring a member such as the retainer ring as described above. It becomes.

  Furthermore, in the method for manufacturing a glass substrate for a magnetic disk according to the present invention, it is preferable that a thickness dimension of a part of the retainer ring or the carrier is 95% or more and 105% or less of a thickness dimension of the glass substrate. If the thickness dimension of the retainer ring or the like is extremely thinner than the glass substrate, sinking of the polishing pad cannot be suppressed. On the other hand, when the thickness dimension is thicker than the glass substrate, no load is applied to the glass substrate, and the polishing rate is reduced. When the thickness dimension of the retainer ring is 95% or more and 105% or less of the thickness dimension of the glass substrate, the sinking of the polishing pad can be effectively suppressed without reducing the polishing rate. It becomes possible.

  Furthermore, in the method for manufacturing a glass substrate for a magnetic disk of the present invention, the area of the retainer ring or the part of the carrier is the area of the main surface of the glass substrate A, the retainer ring or the part of the carrier. When the area of the surface parallel to the main surface of the glass substrate is B, the B / A calculation result is preferably 0.01 to 0.3. If the area of the retainer ring or the like is too small compared to the area of the glass substrate, the sinking of the polishing pad cannot be suppressed. On the other hand, when the area is too large, a load is not applied to the glass substrate, and the polishing rate is reduced. As described above, when the area of the glass substrate is A and the area of the retainer ring is B, and the B / A calculation result is 0.01 to 0.3, the polishing rate decreases. It is possible to effectively suppress the sinking of the polishing pad without incurring.

  The magnetic disk manufacturing method of the present invention is characterized in that at least a magnetic layer is formed on a magnetic disk glass substrate manufactured by any one of the above-described magnetic disk glass substrate manufacturing methods.

  According to this method, since the deterioration of the end shape is improved while maintaining a good surface roughness in the glass substrate, when manufacturing a magnetic disk by forming a magnetic layer or the like on the glass substrate, it is smooth. In addition, a magnetic disk having excellent flatness can be manufactured.

  According to the method for manufacturing a magnetic disk glass substrate and the method for manufacturing a magnetic disk of the present invention, the polishing pad is placed on the main surface of the glass substrate in a state where movement of the polishing pad toward the carrier side in the vicinity of the outer periphery of the glass substrate is restricted. Since the main surface of the glass substrate can be polished while suppressing the situation where the polishing pad sinks to the carrier side during polishing, the polishing is performed using fine loose abrasive grains and a polishing pad with low hardness. Even in this case, it is possible to improve the deterioration of the end shape while maintaining good surface roughness.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. As the material of the glass substrate manufactured by the method for manufacturing a magnetic disk glass substrate (hereinafter referred to as “glass substrate”) according to the present embodiment, aluminosilicate glass, soda lime glass, borosilicate glass, or the like is used. be able to. In particular, aluminosilicate glass can be preferably used in that it can be chemically strengthened and can provide a glass substrate that is excellent in flatness and substrate strength of the main surface.

  About the manufacturing process of a glass substrate, if the outline is described, a cutting process; a shape processing process; a roughening process (first grinding process); a fine lapping process (second grinding process); an end surface polishing process; a main surface polishing process First and second polishing steps); including a chemical strengthening step and the like. In the manufacturing method of the glass substrate according to the present embodiment, in the second polishing step of the main surface polishing step, the use of a double-side polishing apparatus that suppresses the situation where the polishing pad sinks to the carrier side, fine loose abrasive grains Even when polishing is performed using a polishing pad having a low hardness, the deterioration of the end shape is improved while maintaining a good surface roughness in the glass substrate.

  In the glass substrate manufacturing method according to the present embodiment, in the second polishing step of the main surface polishing step, the movement of the polishing pad to the carrier side in the vicinity of the outer periphery of the glass substrate held by the carrier is regulated. The main surface of the glass substrate is polished using a double-side polishing apparatus having a constituent member for bringing the polishing pad into close contact with the main surface of the glass substrate. Specifically, the main surface of the glass substrate is polished using a double-side polishing apparatus in which a retainer ring or the like having substantially the same thickness as the glass substrate is disposed around the glass substrate held by the carrier. In this second polishing step, fine loose abrasive grains (slurry) and a polishing pad with low hardness are used in order to ensure good surface roughness after polishing.

  Hereinafter, the configuration of a double-side polishing apparatus used in the method for manufacturing a glass substrate according to the present embodiment will be described. FIG. 1 is a top view of a double-side polishing apparatus used in the glass substrate manufacturing method according to the present embodiment. In FIG. 1, the upper surface plate of the double-side polishing apparatus is omitted. FIG. 2 is a partial cross-sectional view of a double-side polishing apparatus used in the glass substrate manufacturing method according to the present embodiment. In addition, in FIG. 2, the side part sectional drawing in the dashed-dotted line AA shown in FIG. 1 is shown typically.

  As shown in FIG. 2, in the double-side polishing apparatus used in the method for manufacturing a glass substrate according to the present embodiment, a carrier 4 is placed between an upper surface plate 2 and a lower surface plate 3 to which a polishing pad 1 is attached. A glass substrate 5 held with the portion exposed is disposed. The upper surface plate 2 and the lower surface plate 3 are configured to rotate in opposite directions. Moreover, as shown in FIG. 1, the sun gear 6 and the internal gear 7 are provided between the upper surface plate 2 and the lower surface plate 3, and the carrier 4 is arrange | positioned among these. A gear that meshes with the sun gear 6 and the internal gear 7 is formed on the outer periphery of the carrier 4. Thereby, the sun gear 6 and the internal gear 7 are also rotated with the rotation of the upper surface plate 2 and the lower surface plate 3, and the carrier 4 is rotated and revolved.

  In this double-side polishing apparatus, the glass substrate 5 is sandwiched between the upper surface plate 2 and the lower surface plate 3 while the glass substrate 5 held by the carrier 4 is in close contact between the upper surface plate 2 and the lower surface plate 3. Then, the upper surface plate 2 and the lower surface plate 3 are rotated while supplying a polishing liquid containing fine loose abrasive grains (slurry) between the polishing pad 1 and the polishing surface of the glass substrate 5. The carrier 4 is rotated and revolved through the rotation of the sun gear 6 and the internal gear 7 accompanying the rotation of the upper surface plate 2 and the lower surface plate 3, and both surfaces of the glass substrate 5 held by the carrier 4 are polished simultaneously. Has been.

  In particular, in this double-side polishing apparatus, as shown in FIG. 2, the polishing pad 1 is made of glass in a state where movement of the polishing pad 1 toward the carrier 4 in the vicinity of the outer periphery of the glass substrate 5 held by the carrier 4 is restricted. It has a component that is in close contact with the main surface of the substrate 5. The constituent member for restricting the movement of the polishing pad 1 (hereinafter referred to as “pad restricting member” as appropriate) is, for example, a retainer ring disposed in a holding hole 41 as a holding portion for holding the glass substrate 5 in the carrier 4. 42 or a carrier 4 in which a part of the glass substrate 5 disposed near the outer periphery is deformed. Such a pad regulating member serves to suppress the polishing pad 1 from sinking into the carrier 4 when the main surface of the glass substrate 5 is polished. By providing the pad regulating member in the vicinity of the outer periphery of the glass substrate 5 held by the carrier 4 in this way, it is possible to suppress an increase in the load by the polishing pad 1 on the end of the glass substrate 5 compared to the main surface. It is possible to make it difficult for defects such as roll-off due to the load to occur at the end of the glass substrate 5.

  Here, the case where the pad regulating member provided in the vicinity of the outer periphery of the glass substrate 5 is constituted by the retainer ring 42 will be described. The retainer ring 42 is formed of, for example, a resin material such as glass epoxy or PPS (polyphenylene sulfide), and is provided in an annular shape having an outer diameter substantially the same as the inner diameter of the holding hole 41. The retainer ring 42 is fixed to the wall surface of the holding hole 41 with a resin adhesive or the like, for example. By fixing the retainer ring 42 to the carrier 4 in this way, it is not necessary to arrange the retainer ring 42 on the carrier 4 when performing the main surface polishing step, so that the work efficiency in the main surface polishing step can be improved. It becomes possible.

  Here, the case where the retainer ring 42 is fixed to the carrier 4 is described. However, the retainer ring 42 is not fixed to the carrier 4 and is disposed in the holding hole 41 when performing main surface polishing and fixing. Is also possible. In this case, the fixing work with the resin adhesive or the like on the carrier 4 can be omitted, so that the cost required for manufacturing the double-side polishing apparatus can be reduced.

  As described above, the retainer ring 42 serves to suppress the polishing pad 1 from sinking to the carrier 4 side when the glass substrate 5 is polished. For this reason, if the thickness dimension ts (see FIG. 2) of the retainer ring 42 is extremely thinner than the glass substrate 5, the sinking of the polishing pad 1 cannot be suppressed. On the other hand, if the thickness dimension ts is thicker than the glass substrate 5, no load is applied to the glass substrate 5 and the polishing rate is reduced. For this reason, the thickness dimension ts of the retainer ring 42 is preferably 95% or more and 105% or less of the thickness dimension of the glass substrate 5, and is 100% or more and 101% or less of the thickness dimension of the glass substrate 5. More preferably. When such a thickness dimension ts is set, it is possible to effectively suppress the sinking of the polishing pad 1 without causing a decrease in the polishing rate.

  In addition, if the width dimension bs (see FIG. 2) of the retainer ring 42 is too thin, the sinking of the polishing pad 1 cannot be suppressed, similarly to the thickness dimension ts. On the other hand, if the width dimension bs is too thick, no load is applied to the glass substrate 5 and the polishing rate is lowered. For this reason, the width dimension bs of the retainer ring 42 is B / A when the area of the main surface of the glass substrate 5 is A and the area of the plane parallel to the main surface of the glass substrate 5 in the retainer ring 42 is B. The calculation result is preferably a value of 0.01 to 0.3, and more preferably the calculation result is a value of 0.05 to 0.15. When such a width dimension bs is set, it is possible to effectively suppress the sinking of the polishing pad 1 without causing a decrease in the polishing rate.

  In the above description, the case where the pad restricting member disposed in the vicinity of the outer periphery of the glass substrate 5 is configured by the retainer ring 42 has been described. However, the pad restricting member may be partially deformed by the carrier 4. You may make it comprise with. In this case, the carrier 4 has the function of the retainer ring 42 described above. About the deformation | transformation part in the carrier 4, it is preferable to set to the dimension similar to the retainer ring 42 mentioned above. In this case, the work of placing the retainer ring 42 on the carrier 4 and the work of fixing the retainer ring 42 to the carrier 4 when performing the main surface polishing process can be omitted. Efficiency can be improved.

  Thus, according to the manufacturing method of the glass substrate which concerns on this Embodiment, the said polishing pad 1 is made into the state of the glass substrate 5 in the state which controlled the movement to the carrier 4 side of the polishing pad 1 in the outer periphery vicinity of the glass substrate 5. Since the main surface of the glass substrate 5 can be polished while suppressing the situation where the polishing pad 1 sinks to the carrier 4 side during polishing because the main surface is brought into close contact with the main surface, fine loose abrasive grains and a polishing pad with low hardness Even when polishing is performed using 1, it is possible to improve the deterioration of the end shape while maintaining good surface roughness.

(Example)
Hereinafter, the present invention will be described more specifically based on examples. In this embodiment, the following (1) cutting step, (2) shape processing step, (3) roughening step (first grinding step), (4) fine lapping step (second grinding step), ( 5) A glass substrate 5 is manufactured through an end surface polishing process, (6) a main surface polishing process, (7) a chemical strengthening process, and (8) a magnetic disk manufacturing process. A disc was manufactured.

  In addition, the plate-shaped glass raw material for manufacturing the glass substrate 5 was manufactured by the float glass process. In the float process, the melt is poured over molten tin and solidified as it is. Since both surfaces of the plate glass were the glass free surface and the glass / tin interface, a plate-like glass material having a mirror surface of Ra 0.001 μm or less was obtained without polishing.

(1) Cutting process First, in the cutting process, a plate glass material made of aluminosilicate glass having a thickness of 0.95 mm manufactured by a float process is cut into a square of a predetermined size, and its top surface The circular cut line which draws the outer periphery side of the area | region used as the glass substrate 5 and the substantially peripheral edge of the inner peripheral side was formed in the glass cutter. Then, the top surface side of the sheet glass material on which the cut line is formed is heated by a heater as a whole, and the cut line is advanced to the bottom surface side of the sheet glass material to cut out a glass substrate having a predetermined diameter. It was.

(2) Shape processing step Next, in the shape processing step, after grinding the outer peripheral end face and the inner peripheral end face to an outer diameter of 65 mm and an inner diameter (diameter of the circular hole in the center) of 20 mm, A predetermined chamfering process was performed on the inner peripheral end face. At this time, the surface roughness of the end face of the glass substrate was about 2 μm in Rmax. In general, a 2.5 (inch) type HDD (hard disk drive) uses a magnetic disk having an outer diameter of 65 mm.

(3) Roughening process (first grinding process)
In the roughening step (first grinding step), a mechanical method using loose abrasive polishing with a flat polishing machine was applied. Polishing was performed using loose abrasive polishing so that the entire surface of the glass substrate had a substantially uniform surface roughness (Ra = 0.01 to 0.4 μm). In addition, it is desirable to determine the target surface roughness in the roughening step in relation to the particle size of the fixed abrasive used in the fine lapping step described later.

(4) Precision lapping process (second grinding process)
In the fine lapping step (second grinding step), the main surface of the roughened glass substrate was ground using a fixed abrasive polishing pad. In this fine lapping process, the roughened glass substrate is set in a lapping apparatus, and the surface of the glass substrate is lapped using a diamond sheet, so that the surface roughness Ra is 0.1 μm or less at a high processing rate. Thus, the flatness could be reduced to 7 μm or less.

  Thus, since the main surface of the glass substrate is roughened in advance in the roughening step, fine fixed abrasive grains are formed on the main surface of the glass substrate. Thereby, the malfunction that a fixed abrasive grain slides on the surface of a glass substrate can be prevented. In this case, the processing rate in the fine lapping process can realize a high processing rate from the start of surface polishing.

(5) End surface polishing step In the end surface polishing step, the roughness of the outer peripheral end surface and the inner peripheral end surface of the glass substrate is 0.4 μm for Rmax and 0.1 μm for Ra while rotating the glass substrate by a brush polishing method. Polished to a degree. And the surface of the glass substrate which finished such end surface grinding | polishing was water-washed.

(6) Main surface polishing step (first polishing step, second polishing step)
In the main surface polishing step, first, a first polishing step for removing scratches and distortions remaining in the lapping step was performed using the above-described double-side polishing apparatus. In the first polishing step, the main surface of the glass substrate was polished using a polishing pad 1 whose polisher was a hard polisher (hard foamed urethane). Note that cerium oxide abrasive grains were used as the abrasive.

  Next, in the second polishing step in which the second polishing step is performed using the same double-side polishing apparatus used in the first polishing step, the glass substrate is replaced with the polishing pad 1 in which the polisher is a soft polisher (suede). The main surface was polished. In addition, as abrasive | polishing agent, the silica abrasive grain finer than the cerium oxide abrasive grain used at the 1st grinding | polishing process was used. In the second polishing step, Ra <0.15 nm and Dub-off <10 nm or less are achieved by using the retainer ring 42 described above while maintaining the flat surface obtained in the first polishing step described above. I was able to achieve it.

(7) Chemical strengthening process In the chemical strengthening process, the glass substrate which finished the lapping process and the polishing process described above was chemically strengthened. In this case, ion exchange was performed on ions (Na ⁺ and K ⁺ ) having a larger ion radius than ions existing on the surface of the glass substrate (for example, Li ⁺ and Na ^{+ in} the case of using an aluminosilicate glass). Here, on the surface of the glass substrate (for example, up to about 5 μm from the surface of the glass substrate), ions are exchanged with atoms having a large ion radius, and the glass substrate surface is given a compressive stress to increase the rigidity of the glass substrate. Yes.

  Thus, after the cutting process, the shape processing process, the roughening process (first grinding process), the fine lapping process (second grinding process), the end surface polishing process, the main surface polishing process, and the chemical strengthening process, And the glass substrate 5 for magnetic disks which has smooth high rigidity was obtained.

(8) Magnetic disk manufacturing process In the magnetic disk manufacturing process, a seed layer, an underlayer, a magnetic layer, and a protective layer are formed on both surfaces of the glass substrate 5 using a sputtering apparatus, and a lubricating layer is formed. Magnetic disks were manufactured. In this case, the seed layer was formed with a first seed layer made of a CrTi thin film and a second seed layer made of an AlRu thin film. The underlayer was a CrW thin film and was provided to improve the crystal structure of the magnetic layer. The magnetic layer is made of a CoPtCrB alloy. The protective layer is for preventing the magnetic layer from deteriorating due to contact with the magnetic head, and is made of hydrogenated carbon, and provides wear resistance. The lubricating layer was formed by dipping a liquid lubricant of perfluoropolyether. In this way, a magnetic disk using the glass substrate 5 described above was obtained.

(Comparative example)
In the comparative example, the glass substrate 5 was manufactured under the same conditions as in the example except that the configuration of the double-side polishing apparatus used in the main surface polishing step was partially changed. Specifically, as shown in FIG. 3, the main surface polishing step was performed using a double-side polishing apparatus not provided with the above-described pad regulating member (Comparative Example 1). Moreover, as shown in FIG. 4, the main surface polishing process was performed using the double-side polish apparatus which has the carrier 4 set to the substantially same thickness dimension as the glass substrate 5 (comparative example 2). And the surface roughness of the glass substrate 5 manufactured by the Example, the comparative example 1, and the comparative example 2 and the state of edge part shape were investigated, and the result shown in FIG. 5 was obtained. In addition, the surface roughness in the manufactured glass substrate 5 was measured using AFM (atomic force microscope). Moreover, the edge part shape of the glass substrate 5 was determined by whether it exceeded the incidence rate of predetermined malfunctions (for example, roll-off and ski jump).

  As can be seen from FIG. 5, in the glass substrate 5 manufactured in the example, good results were obtained in both surface roughness and edge shape. On the other hand, in the glass substrate 5 manufactured in Comparative Example 1, although good results were obtained in the surface roughness, defects such as roll-off more than a predetermined level were observed in the end shape, and good results were obtained. There wasn't. In addition, in the glass substrate 5 manufactured in Comparative Example 2, the desired surface roughness cannot be obtained in the surface roughness, and defects such as roll-off more than a predetermined level are observed in the end shape, both are good. Results were not obtained.

  From this, according to the glass substrate 5 manufactured in the Example, even when polishing using fine loose abrasive grains (slurry) and a polishing pad with low hardness, good surface roughness is maintained. In addition, it can be seen that the deterioration of the end shape is improved. In addition, since the pad regulating member is disposed only in the vicinity of the outer periphery of the glass substrate 5, it is possible to avoid a situation in which the load due to the polishing pad 1 is not applied to the glass substrate. Never do.

  The present invention is not limited to the above embodiment, and can be implemented with appropriate modifications. In the said embodiment, although the case where chemical strengthening is performed after performing the 1st grinding | polishing process and the last grinding | polishing process with respect to a glass substrate is demonstrated, this invention is not limited to this, The same can be applied to the case where the chemical strengthening is performed after the first polishing process and the final polishing process is performed thereafter. Further, the material, number, size, processing procedure, and the like in the above embodiment are merely examples, and various modifications can be made within the range where the effects of the present invention are exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  In the present invention, fine loose abrasive grains and a low-hardness polishing pad are obtained by bringing the polishing pad into close contact with the main surface of the glass substrate in a state where the movement of the polishing pad toward the carrier side in the vicinity of the outer periphery of the glass substrate is regulated. Even when polishing is performed, it is intended to improve the deterioration of the end shape while maintaining good surface roughness, and has industrial applicability.

It is a top view of the double-side polish apparatus used for the manufacturing method of the glass substrate which concerns on this Embodiment. It is a fragmentary sectional view of the double-side polish apparatus used for the manufacturing method of the glass substrate which concerns on the said embodiment. It is a fragmentary sectional view of the double-side polish apparatus used for the manufacturing method of the glass substrate which concerns on the comparative example 1 of the said embodiment. It is a fragmentary sectional view of the double-side polish apparatus used for the manufacturing method of the glass substrate which concerns on the comparative example 2 of the said embodiment. It is a figure for demonstrating the effect of the glass substrate produced by the manufacturing method of the glass substrate which concerns on the said embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polishing pad 2 Upper surface plate 3 Lower surface plate 4 Carrier 41 Holding hole part 42 Retainer ring 5 Glass substrate 6 Sun gear 7 Internal gear

Claims (5)

A method for producing a glass substrate for a magnetic disk comprising a polishing step of polishing a main surface of a glass substrate held in a state where a part is exposed from a carrier,
The retainer ring having the glass substrate substantially the same thickness in the holding portion of the glass substrate in the carrier is arranged, by holding the glass substrate at the inner circumferential surface of the retainer ring, the pre-Symbol glass substrate The polishing pad is brought into close contact with the main surface of the glass substrate in a state where movement of the polishing pad toward the carrier in the vicinity of the outer periphery is regulated, and the main surface of the glass substrate is polished by rotating the carrier. A method of manufacturing a glass substrate for a magnetic disk.   A part of the carrier disposed in the vicinity of the outer periphery of the glass substrate is provided with substantially the same thickness as the glass substrate, and the movement of the polishing pad to the carrier side is restricted by a part of the carrier. The method for producing a glass substrate for a magnetic disk according to claim 1. A portion of the thickness dimension of the retainer ring or the carrier, according to claim 1 or claim 2 glass substrate for a magnetic disk, wherein said at most 105% 95% or more the thickness of the glass substrate Manufacturing method. The area of the retainer ring or a part of the carrier is defined as A for the area of the main surface of the glass substrate and B for the area of the retainer ring or a part of the carrier parallel to the main surface of the glass substrate. The method for producing a glass substrate for a magnetic disk according to any one of claims 1 to 3 , wherein the calculation result of B / A is 0.01 to 0.3. Glass substrate for a magnetic disk produced by the production method of the glass substrate according to any one of claims 1 to 4, a manufacturing method of a magnetic disk, which comprises forming at least a magnetic layer.

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