JP2012111013A - Polished body suction jig, manufacturing method for glass substrate, and glass substrate for magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a trace produced when a glass substrate is sucked.SOLUTION: A polished body suction jig 10 has a cylinder 60, an operation member 70, a spring member 80, a pedestal 90, and a suction pad 100. The operation member 70 is held at an upper movement position (negative pressure stop position) where a pressed operation part 78 protrudes upward from a cylinder chamber 62 of the cylinder 60 by spring force of the spring member 80 when the pressed operation part 78 is not press-operated. Then, in the operation member 70, if the pressed operation member 78 is press-operated downward against spring force of the spring member 80, a second communication hole 76 is communicated with a negative pressure introduction hole 64, and negative pressure is introduced to a suction surface of the suction pad 100. Further, if pressing operation of the operation member 70 is released, the first communication hole 74 is moved upward by the spring force of the spring member 80 and is returned to the upper movement position where it is communicated with an air introduction hole 66.

Description

  The present invention relates to an object to be polished adsorption jig for adsorbing the surface of an object to be polished, a method for manufacturing a glass substrate, and a glass substrate for a magnetic recording medium.

  As an object to be polished by a polishing apparatus, for example, in addition to a glass substrate used for a glass substrate for a magnetic recording medium, for a photomask, for a display such as a liquid crystal or an organic EL, an optical pickup element, an optical filter, an optical lens There are glass substrates for optical components such as. Below, the case where the glass substrate for magnetic recording media is grind | polished is demonstrated as an example.

  In the polishing process of the glass substrate (object to be polished), the main plane of the glass substrate is polished to finish the surface to a predetermined surface roughness or less. The glass substrates that have undergone the polishing process are taken out one by one by workers, inserted into the respective storage portions of the glass substrate storage container, and sent to the inspection process.

  In the inspection process, the surface roughness or undulation of the glass substrate is inspected using an optical surface inspection apparatus (for example, OSA (Optical Surface Analyzer) 6300 manufactured by KLA-Tencor). With this inspection device, it is possible to measure extremely fine defects that could not be detected in the past. For example, a fine defect that occurs when an operator's finger touches when removing a glass substrate from a polishing device. Traces such as waviness (local roughness defects) can also be measured.

  When polishing the main plane of the glass substrate, since the main plane of the glass substrate is mirror finished by performing the polishing process 2 to 4 times, when taking out the glass substrate after the final polishing process from the polishing apparatus, Workers are prevented from touching the main plane of the glass substrate.

  Further, in the conventional glass substrate taking-out operation in the polishing process, a method of taking out the glass substrates one by one from the polishing apparatus using a vacuum suction type glass substrate suction jig and inserting them into the glass substrate storage container has also been performed. (For example, refer to Patent Document 1). When taking out the glass substrate from the polishing apparatus using the glass substrate suction jig described in Patent Document 1, since the worker does not touch the main plane of the glass substrate, there is a trace when the fingertip contacts the glass substrate. Does not remain.

JP 2007-21611 A

  When taking out the glass substrate from the polishing apparatus manually by the conventional worker, if the fingertip of the worker accidentally touches the main surface of the glass substrate, the inspection of the glass substrate by the optical surface inspection apparatus is performed. Since the trace of the fingertip remaining on the main plane is detected, the glass substrate becomes a defective product.

  Moreover, in the said patent document 1, it is the structure which adsorb | sucks a glass substrate by generating a negative pressure to an adsorption pad by an operator closing the air hole (open hole) connected to the atmosphere of the glass substrate adsorption jig by hand. Therefore, the operability is bad, for example, if there is a gap between the air hole (open hole) closed by hand, air is supplied to the suction pad, the suction force is reduced, and the glass substrate falls was there.

  In the glass substrate suction jig, since the air hole (open hole) is opened, dust in the atmosphere may adhere to the suction surface of the suction pad due to negative pressure, and the suction pad is attached to the glass substrate. If the suction surface of the suction pad is rubbed against the main plane of the glass substrate when contacting, there is a risk that scratches or fine traces may remain on the main plane.

  In addition, when the suction pad is dried, dust adheres to the suction surface of the suction pad. Therefore, it is desired to store the suction surface of the suction pad in water. Even when the air hole (open hole) is open at times, water is continuously sucked from the suction pad, which makes it difficult to store the suction pad in water.

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an object-to-be-ground-adsorbing jig, a glass substrate manufacturing method, and a magnetic recording medium glass substrate that have solved the above problems.

In order to solve the above problems, the present invention has the following means.
(1) The present invention relates to an object-adsorbing jig having an adsorption pad that adsorbs the main plane of the object to be polished.
An air suction hole communicating with the suction surface of the suction pad;
A cylinder communicated with the air suction hole;
An operating member inserted into the cylinder;
A spring member that returns the operating member to a negative pressure stop position before the operation,
When the operating member is pressed against the spring force of the spring member, negative pressure is generated on the suction surface of the suction pad, and when the pressing operation on the operating member is released, the spring member The operation member is returned to a negative pressure stop position by a spring force, and the suction surface of the suction pad is set to atmospheric pressure.
(2) The suction pad of the present invention comprises:
An adsorption layer having an adsorption surface in contact with the main plane of the object to be polished;
A support layer adhered to the back surface of the adsorption layer;
An adhesive layer that adheres the back surface of the support layer to a pedestal;
Are laminated.
(3) The said support layer of this invention is formed with a nonwoven fabric.
(4) In the present invention, the contour shape of the adsorption layer and the support layer is smaller than the outer periphery of the object to be polished and is a non-circular shape.
(5) The said to-be-polished body of this invention is a glass substrate for magnetic recording media.
(6) The present invention relates to a method for manufacturing a glass substrate, in which after the main plane of the glass substrate is polished, the glass substrate is taken out using the object suction jig according to any one of (1) to (4). There,
After the polishing of the main plane of the glass substrate is completed, the procedure 1 is to bring the suction surface of the suction pad of the workpiece suction jig into contact with the main plane of the glass substrate;
A procedure 2 for generating a negative pressure on the suction surface by pressing the operation member of the object to be polished;
Procedure 3 for taking out the glass substrate together with the object to be polished suction jig in a state where the suction surface of the object to be polished chucking is in close contact with the glass substrate;
With the outer periphery of the glass substrate inserted into each storage part of the polishing object storage container, the pressing operation of the operation member of the polishing object suction jig is released to stop the negative pressure generation of the suction pad. Procedure 4 for inserting the glass substrate into the storage part of the object storage container;
Have
(7) The glass substrate of the present invention is a glass substrate for a magnetic recording medium.
(8) The present invention provides a magnetic recording medium for a magnetic recording medium that is taken out from the polishing apparatus using the polishing object adsorption jig according to any one of (1) to (4) after the main surface is polished by the polishing apparatus. A glass substrate,
The glass substrate for a magnetic recording medium is a glass substrate for a magnetic recording medium having no local roughness defect measured using scattered light obtained by irradiating a laser beam having a wavelength of 405 nm in a recording / reproducing region on a main plane. is there.
(9) The present invention is a disk-shaped glass substrate for a magnetic recording medium having a circular hole in the center,
The magnetic recording medium glass substrate has no local roughness defect measured by using scattered light obtained by irradiating a laser beam having a wavelength of 405 nm in a recording / reproducing region of a main plane. It is a glass substrate for media.

  According to the present invention, since the negative pressure is generated on the suction surface of the suction pad by operating with the operation member inserted into the cylinder connected to the air suction hole communicating with the suction surface of the suction pad, the suction pad is covered with the suction pad. The polishing body can be reliably adsorbed, dust in the atmosphere can be prevented from entering the air suction holes, and traces due to rubbing of the suction pad can be suppressed from occurring on the main plane of the object to be polished. In addition, when non-adsorption, the operation member prevents the negative pressure from being introduced and allows the suction pad to be stored in water, prevents dust from adhering due to drying of the adsorber pad, and adheres to the object by adhering the object to be polished. Scratches and traces can be prevented.

It is a figure which shows typically the operation | movement procedure of one Example of the to-be-polished object adsorption | suction jig by this invention. It is a longitudinal cross-sectional view which shows the structure of a to-be-polished object adsorption jig. It is a top view of a to-be-polished object adsorption jig. It is a top view of the suction pad with which a to-be-polished object suction jig is equipped. It is a longitudinal cross-sectional view which expands and shows the laminated structure of a suction pad. It is a longitudinal cross-sectional view which shows the state of a to-be-polished body adsorption | suction jig | tool when a glass substrate is adsorbed. It is a longitudinal cross-sectional view which shows the state of a to-be-polished object adsorption jig when a glass substrate is isolate | separated. Inspection image of the entire measurement area and local roughness defect obtained by measuring the local roughness defect left on the main plane with an optical surface inspection device when the operator manually removes the glass substrate It is a figure which shows an example of the test | inspection image which expanded and displayed. It is the figure which expanded and displayed an example of the test | inspection image which measured the local roughness defect left on the main plane when an operator removed the glass substrate by the optical surface inspection apparatus.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
[How to use the workpiece suction jig]
FIG. 1 is a view schematically showing a work procedure of an embodiment of an object to be polished suction jig according to the present invention. As shown in FIG. 1, when the final polishing step (finishing step) by the polishing apparatus 20 is completed, the upper surface plate 30 moves upward, and the glass substrate W (covered) polished on the polishing pad 42 of the lower surface plate 40 is obtained. Abrasive body) is left. The worker P uses the object to be polished suction jig 10 to pick up and take out each glass substrate W after the final polishing one by one and take care to avoid touching the surface of the glass substrate. Insert into storage container.

  The glass substrate W is inserted into each holding hole of the carrier made of a resin sheet and polished. However, when the object to be polished object suction jig 10 is used, the carrier may be removed first, or The glass substrate may be taken out while leaving the carrier.

  The object to be polished suction jig 10 is configured so that a suction pad, which will be described later, is brought into close contact with the main plane of the glass substrate W by the operation of the worker P, and the glass substrate W is sucked by the negative pressure generated by the vacuum generator 50. Has been. The vacuum generator 50 has a built-in negative pressure tank that is depressurized below the atmospheric pressure, and the negative pressure tank is connected to the workpiece suction jig 10 via a vacuum tube 52.

Further, the worker P holds the gripping part 12 of the workpiece suction jig 10 to bring the suction pad into close contact with the main plane of the glass substrate W, and introduces a negative pressure from the vacuum generator 50 to the suction pad. Then, the glass substrate W is lifted from the lower surface plate 40 and taken out together with the object to be polished suction jig 10.
[Configuration of Polishing Object Adsorption Jig 10]
FIG. 2 is a longitudinal sectional view showing the configuration of the object to be polished suction jig 10. As shown in FIG. 2, the object to be polished suction jig 10 includes a cylinder 60, an operation member 70, a spring member 80, a pedestal 90, and a suction pad 100.

  The cylinder 60 is coupled to the outer periphery so that the grip portions 12 and 13 extend in the horizontal direction. The grip portion 12 is formed of a hollow pipe and has a negative pressure introduction passage 14 therein. The vacuum tube 52 from the vacuum generator 50 described above is connected to the end of the negative pressure introduction passage 14.

  The cylinder 60 is formed in a cylindrical shape from a metal material such as stainless steel, for example, and includes a cylinder chamber 62 in which the operation member 70 slides, a negative pressure introduction hole 64 communicated with the cylinder chamber 62 from the horizontal direction, and An air introduction hole 66 is provided. The negative pressure introduction hole 64 is provided at a height position different from that of the atmosphere introduction hole 66. In the present embodiment, the negative pressure introduction hole 64 is provided at a position higher than the atmosphere introduction hole 66.

  The operation member 70 is composed of a spool valve inserted so as to be slidable in the vertical direction inside the cylinder chamber 62. The operation member 70 includes a central hole 72 extending in the axial direction from the bottom and an intermediate portion between the central hole 72 and the central hole 72. A first communication hole 74 that communicates with the position and a second communication hole 76 that communicates with the upper end position of the central hole 72 are provided.

  The first communication hole 74 is provided at a position where the operation member 70 communicates with the air introduction hole 66 when the operation member 70 is at the negative pressure stop position raised by the spring force of the spring member 80. The second communication hole 76 is provided at a position where the second communication hole 76 communicates with the negative pressure introduction hole 64 when the operation member 70 is pressed downward.

  The operation member 70 is provided with a pressed operation portion 78 at the upper end, and is provided with an escape preventing collar 79 that abuts against the step portion 68 of the cylinder chamber 62 at the lower end. Further, the operating member 70 has an upward movement position (negative pressure) in which the pressed operation portion 78 protrudes upward from the cylinder chamber 62 of the cylinder 60 by the spring force of the spring member 80 when the pressed operation portion 78 is not pressed. (Stopped position) When the pressed operation portion 78 is pressed downward, the operation member 70 is connected to the negative pressure introduction hole 64 by the second communication hole 76 and the pressing operation to the pressed operation portion 78 is released. Then, the spring member 80 is moved upward by the spring force, and the first communication hole 74 returns to the upward movement position (negative pressure stop position) where the first communication hole 74 communicates with the atmosphere introduction hole 66. Therefore, the cylinder 60 and the operation member 70 constitute a switching valve that switches the adsorption or separation with respect to the glass substrate W.

  When the operation member 70 is held at the upward movement position (negative pressure stop position), the escape preventing collar 79 abuts against the stepped portion 68 of the cylinder chamber 62 and is prevented from popping upward.

  Further, the cylinder 60 is configured such that dust in the air does not enter the cylinder chamber 62 because the upper end opening of the cylinder chamber 62 is closed by the operation member 70. Therefore, in the object to be polished suction jig 10, when the operator opens the air hole with the fingertip as in the prior art shown in Patent Document 1 described above, dust in the air does not enter from the air hole, and the suction pad Dust does not adhere to the surface.

  The spring member 80 is formed of, for example, a coil spring made of a stainless material that hardly corrodes.

  The pedestal 90 is formed in an oval shape (non-circular shape), for example, by a resin material, the cylinder 60 is fixed to the upper surface in a vertical state, and the suction pad 100 is bonded to the lower surface. The pedestal 90 is provided with a central hole 92 communicating with the cylinder chamber 62 of the cylinder 60 at the center of the upper surface and branch holes 94 at a plurality of locations on the lower surface. The central hole 92 and the plurality of branch holes 94 are connected by a communication path 96.

  Further, at the time of non-adsorption, the polishing object adsorption jig 10 is stored in water so that the adsorption pad 100 is not dried. In this underwater storage, for example, by immersing the suction pad 100 in water stored in a tray or the like, the suction pad 100 is prevented from drying, and dust is prevented from adhering to the suction surface of the suction pad 100. In addition, since the negative pressure introduction hole 64 is blocked by the operation member 70 when the object to be polished is sucked, water is not sucked even when the suction pad 100 is stored in water, and the suction pad 100 Drying can be prevented. Therefore, it is possible to prevent scratches and traces from remaining on the glass substrate due to drying of the suction pad 100 when the object to be polished is sucked.

  FIG. 3A is a plan view of the workpiece suction jig 10. As shown in FIG. 3A, the pedestal 90 is formed in an oval shape (non-circular shape) in which two places whose outer peripheral shapes are circular are cut in a straight line, and a pair of relief portions 98 and 99 are provided. . The pedestal 90 has an outer diameter D1 smaller than the outer diameter D of the glass substrate W (indicated by a one-dot chain line) and larger than the width L1 of the pair of relief portions 98 and 99 (D> D1> L1).

  Therefore, when the adsorbed glass substrate W is removed from the adsorbing pad 100, it becomes easy to grip the outer periphery (the outer peripheral edge of the main plane) of the glass substrate W protruding outward from the escape portions 98 and 99. The escape portions 98 and 99 may have a linear shape as shown in FIG. 3A or an arbitrary curved shape. Further, the number of the branch holes 94 and the interval between the branch holes 94 are appropriately selected and may be other than the pattern shown in FIG. 3A.

  FIG. 3B is a plan view of the suction pad 100 attached to the workpiece suction jig 10. As shown in FIG. 3B, the suction pad 100 is provided with a pair of relief portions 102 and 103 on the outer periphery, and is formed in an oval shape similar to the pedestal 90. Further, the suction pad 100 has an outer diameter D2 smaller than the outer diameter D of the glass substrate W (indicated by a one-dot chain line) and larger than the width L2 of the pair of relief portions 102 and 103 (D> D2> L2).

Furthermore, suction holes 104 into which negative pressure or atmospheric pressure from the vacuum generator 50 is selectively introduced are provided at four positions at intervals of 90 degrees in the suction pad 100. The escape portions 102 and 103 may have a linear shape as shown in FIG. 3B or an arbitrary curved shape. Further, the number of the suction holes 104 and the interval between the suction holes 104 are appropriately selected so as to be opposed to the respective branch holes 94 of the pedestal 90, and may be other than the pattern shown in FIG. 3B.
[Laminated structure of suction pad 100]
FIG. 4 is an enlarged longitudinal sectional view showing the laminated structure of the suction pad 100. As shown in FIG. 4, the suction pad 100 is attached to the lower surface of the pedestal 90, and the suction layer 106, the support layer 107, and the adhesive layer 108 are laminated.

  The adsorption layer 106 is made of, for example, elastic polyurethane foam, and has an adsorption surface 106 a that contacts the main plane of the glass substrate W. Moreover, the thickness of the adsorption layer 106 is set within a range of 200 μm to 700 μm, and in the present embodiment, it is preferably about 400 μm to 500 μm. Since the adsorption layer 106 absorbs an impact when the adsorption surface 106a comes into contact with the main plane of the glass substrate W, no traces (local roughness defects) such as scratches and undulations remain on the main plane of the glass substrate W. Has softness.

  The support layer 107 is adhered to the back surface (upper surface) of the adsorption layer 106 and is formed of polyethylene terephthalate (PET) or a nonwoven fabric. When the support layer 107 is polyethylene terephthalate (PET), the thickness of the support layer 107 is set in the range of 100 μm to 300 μm, and is preferably 200 μm. Moreover, when the support layer 107 is a nonwoven fabric, the thickness of the support layer 107 is set in the range of 200 μm to 700 μm, and is preferably about 400 μm to 500 μm. Polyethylene terephthalate (PET) or non-woven fabric is interposed between the adsorption layer 106 and the adhesive layer 108 as a buffer material. Further, since the non-woven fabric does not generate burrs when the suction holes 104 are processed, there is no possibility that the burrs generated by the hole processing will cause scratches on the glass substrate W. Therefore, the support layer 107 is preferably a nonwoven fabric.

  The adhesive layer 108 is made of, for example, a sheet-like double-sided tape using a polyester film or the like as a base material in order to adhere the back surface (upper surface) of the support layer 107 to the lower surface of the pedestal 90.

  The adsorption layer 106, the support layer 107, and the adhesive layer 108 are in close contact with each other in a stacked state, and are integrated. Further, the suction layer 106, the support layer 107, and the adhesive layer 108 are provided with suction holes 104 penetrating in the vertical direction. The suction hole 104 has an upper end communicating with the branch hole 94 of the pedestal 90 and a lower end opened to the suction surface 106a.

  Therefore, when the pressed operation portion 78 of the operation member 70 is pressed, the second communication hole 76 communicates with the negative pressure introduction hole 64, so that the central hole 72 of the operation member 70, the cylinder chamber 62 of the cylinder 60, A negative pressure is introduced into the suction hole 104 through the central hole 92, the communication path 96, and the branch hole 94 of the base 90.

Further, since the suction pad 100 is adhered to the base 90 by the adhesive layer 108, the suction pad 100 is periodically replaced before the suction layer 106 is worn or deformed.
[Operation Method of Polishing Object Suction Jig 10]
FIG. 5A is a longitudinal cross-sectional view showing a state of the object to be polished suction jig 10 when a glass substrate is sucked. FIG. 5B is a longitudinal sectional view showing a state of the object to be polished suction jig 10 when the glass substrate is separated.

Here, an operation procedure when taking out the glass substrate W after the final polishing step from the polishing apparatus 20 will be described.
(Procedure 1) As shown in FIG. 5A, first, a worker P (see FIG. 1) grips the gripping portions 12 and 13 of the polishing object suction jig 10 and sets the suction surface 106a of the suction pad 100 to the glass substrate. Adhere to the upper surface (main plane) of W. In this state, since the operation member 70 is held at the upward movement position (negative pressure stop position) by the spring force of the spring member 80, no negative pressure is introduced into the suction pad 100, and the suction hole 104 becomes atmospheric pressure. ing. Further, since the suction pad 100 is integrated in a laminated structure including the suction layer 106, the support layer 107, and the adhesive layer 108, scratches, local roughness defects, and the like are given to the main plane of the glass substrate W by the adhesion operation. There is nothing. Furthermore, since the suction pad 100 is stored in water when it is not suctioned, dust does not adhere to the suction surface of the suction pad 100. From this point, scratches, local roughness defects, etc. Never give.
(Procedure 2) In this close contact state, the worker P presses the pressed operation portion 78 of the operation member 70. As a result, the operation member 70 of the object to be polished suction jig 10 has the second communication hole 76 communicated with the negative pressure introduction hole 64 and the first communication hole 74 and the air introduction hole 66 are blocked. Is done. Therefore, the negative pressure of the vacuum generator 50 is introduced into the negative pressure introduction passage 14 of the grip portion 12 through the vacuum tube 52, and further, the central hole 72 of the operation member 70, the cylinder chamber 62 of the cylinder 60, and the central hole 92 of the pedestal 90. The negative pressure is introduced into the suction hole 104 of the suction pad 100 through the communication path 96 and the branch hole 94.

Accordingly, the glass substrate W is reliably sucked to the suction surface 106a of the suction pad 100 because the four suction holes 104 are decompressed to an atmospheric pressure or lower. Moreover, in this Embodiment, since the to-be-pressed operation part 78 of the operation member 70 is pressed down, the glass substrate W can be adsorb | sucked more reliably than the case where the air hole is plugged up by hand like the conventional patent document 1 mentioned above. At the same time, the burden on workers can be reduced.
(Procedure 3) The worker P lifts the grips 12 and 13 of the polished object suction jig 10 and takes out the glass substrate W after the final polishing process from the polishing apparatus 20. The worker P presses the pressed operation portion 78 of the operation member 70 and maintains the suction state until the glass substrate W is inserted into the glass substrate storage container.
(Procedure 4) As shown in FIG. 5B, when the glass substrate W is moved above the glass substrate storage container 120, the pressing operation of the pressed operation portion 78 of the operation member 70 is released. As a result, the operating member 70 is returned to the upward movement position (negative pressure stop position) by the spring force of the spring member 80, so that the first communication hole 74 is communicated with the atmosphere introduction hole 66 and the second communication hole. The space between 76 and the negative pressure introducing hole 64 is blocked. For this reason, the atmospheric pressure introduced from the air introduction hole 66 passes through the central hole 72 of the operation member 70, the cylinder chamber 62 of the cylinder 60, the central hole 92 of the pedestal 90, the communication path 96, and the branch hole 94. To be introduced. Therefore, the glass substrate W is separated from the suction pad 100 by its own weight and falls into the glass substrate storage container 120.

  When the glass substrate W is not separated while being attracted to the suction surface 106a of the suction pad 100, the glass substrate W is dropped by pressing the portion protruding outward from the escape portions 102 and 103 shown in FIG. 3B.

5B shows that the glass substrate W is dropped into the glass substrate storage container 120 in a horizontal state. However, the present invention is not limited thereto, and for example, each storage unit of the glass substrate storage container 120 holds the glass substrate W in a vertical state. In the case of the storage configuration, the direction of the polishing object suction jig 10 is rotated by 90 degrees, and the pressing operation of the pressed operation portion 78 may be released while the glass substrate W is in the vertical state.
[Inspection result by optical surface inspection equipment]
The presence or absence of local roughness defects on the main surface of the glass substrate is determined by using an optical surface inspection apparatus (for example, OSA (Optical Surface Analyzer) 6300 manufactured by KLA-Tencor), and the roughness or waviness of the main surface of the glass substrate. Inspected by measuring etc.

  FIG. 6A and FIG. 6B are inspections in which local roughness defects left on the main plane when the glass substrate W is taken out without using the object to be polished suction jig 10 according to the present invention are imaged by an optical surface inspection apparatus. It is a figure which shows an example of an image. When an operator manually removes the glass substrate W as in the prior art, it has been confirmed that the traces N1 and N2 due to the pressing force of the fingertip remain on the surface of the glass substrate W. The traces N1 and N2 are local roughness defects on the main plane of the magnetic recording medium glass substrate. The local roughness defect of the main plane causes a problem when a thin film such as a magnetic layer is formed on a glass substrate for a magnetic recording medium to form a magnetic disk and HDD inspection is performed. For this reason, the glass substrate W on which the traces N1 and N2 are confirmed falls within the rejected range as the inspection determination result.

By using the object to be polished suction jig 10 of the present invention, the glass substrate W1 can be reliably sucked and taken out, and traces (local roughness defects) due to the suction work are generated on the main plane of the glass substrate W. And a glass substrate for a magnetic recording medium free from local roughness defects can be obtained.
[About the manufacturing method of the glass substrate for magnetic recording media]
Generally, the manufacturing process of the glass substrate for magnetic recording media and the magnetic disk includes the following processes. (Step 1) After processing the glass base substrate formed by the float method, the fusion method or the press molding method into a disk shape having a circular hole in the central portion, the inner peripheral side surface and the outer peripheral side surface are chamfered.
(Step 2) The side surface portion and the chamfered portion of the glass substrate are end-polished.
(Step 3) The main plane of the glass substrate is polished. The polishing step may be primary polishing only, primary polishing and secondary polishing may be performed, or tertiary polishing may be performed after secondary polishing.
(Step 4) Precision cleaning of the glass substrate is performed to obtain a glass substrate for a magnetic recording medium.
(Step 5) A thin film such as a magnetic layer is formed on a glass substrate for a magnetic recording medium to manufacture a magnetic disk.

  In the manufacturing process of the glass substrate for magnetic recording medium and the magnetic disk, (step 2) wrapping of the main plane (for example, loose abrasive wrap, fixed abrasive wrap, etc.) is performed at least one of before and after the end face polishing step. Alternatively, glass substrate cleaning (inter-process cleaning) and glass substrate surface etching (inter-process etching) may be performed between the processes. Note that main surface lap (for example, loose abrasive wrap, fixed abrasive wrap, etc.) is polishing of the main surface in a broad sense.

  Furthermore, when high mechanical strength is required for the glass substrate for magnetic recording media, a strengthening step (for example, a chemical strengthening step) for forming a reinforcing layer on the surface layer of the glass substrate is performed before the polishing step, after the polishing step, or the polishing step. You may carry out between.

  In the present invention, the glass substrate for a magnetic recording medium may be amorphous glass, crystallized glass, or tempered glass (for example, chemically tempered glass) having a tempered layer on the surface layer of the glass substrate. Further, the glass base substrate of the glass substrate of the present invention may be made by a float method, may be made by a fusion method, or may be made by a press molding method.

Here, adjustment, polishing, and inspection of the glass substrate for a magnetic recording medium will be described in detail.
[Adjustment of glass substrate for magnetic recording medium]
For example, a case where a glass substrate for a magnetic recording medium having an outer diameter of 65 mm, an inner diameter of 20 mm, and a plate thickness of 0.635 mm is manufactured will be described. First, a glass substrate mainly composed of SiO ₂ formed by a float process is processed into a donut-shaped circular glass substrate (a disk-shaped glass substrate having a circular hole in the center).

  The doughnut-shaped circular glass substrate is chamfered so that a glass substrate for a magnetic recording medium having a chamfering width of 0.15 mm and a chamfering angle of 45 ° is obtained on the inner peripheral side surface and the outer peripheral side surface. The upper and lower main planes of the substrate are lapped and the abrasive grains are washed away.

  Next, the inner peripheral side surface and the inner peripheral chamfered portion were polished using a polishing brush and cerium oxide abrasive grains, scratches on the inner peripheral side surface and the inner peripheral chamfered portion were removed, and the inner peripheral end surface was polished so as to be a mirror surface. The glass substrate subjected to the inner peripheral end face polishing is cleaned and removed of the abrasive grains.

Polish the outer peripheral side surface and outer peripheral chamfered portion of the glass substrate after polishing the inner peripheral end surface with a polishing brush and cerium oxide abrasive grains, remove scratches on the outer peripheral side surface and outer peripheral chamfered portion, and polish the outer peripheral end surface so that it becomes a mirror surface did. The abrasive grains are washed and removed from the glass substrate after the outer peripheral end surface is polished.
[Primary to tertiary polishing of glass substrate for magnetic recording medium]
The glass substrate after the end face processing is a polishing liquid containing a polishing pad made of hard urethane and cerium oxide abrasive grains as an abrasive (average particle diameter, hereinafter abbreviated as average particle diameter, about 1.3 μm of cerium oxide as a main component. The upper and lower main planes are subjected to primary polishing using a 22B double-side polishing apparatus (product name: DSM22B-6PV-4MH, manufactured by Speedfam Co., Ltd.).

  The glass substrate after the primary polishing is a polishing liquid containing a polishing pad made of soft urethane as a polishing tool and cerium oxide abrasive grains having an average particle diameter smaller than that of the cerium oxide abrasive grains (average particle diameter of about 0.5 μm). The upper and lower main planes are subjected to secondary polishing using a 22B double-side polishing apparatus (product name: DSM22B-6PV-4MH, manufactured by Speedfam Co., Ltd.).

  The glass substrate after the secondary polishing is composed of a polishing pad made of soft urethane as a polishing tool and a polishing liquid containing colloidal silica (a polishing liquid composition mainly composed of colloidal silica having an average primary particle diameter of 20 to 30 nm). The upper and lower main planes are subjected to third polishing by a double-side polishing apparatus.

  In the present embodiment, the object suction jig 10 of the present invention is used when the glass substrate after the third polishing which is the final finish polishing step is picked up from the polishing apparatus.

  The glass substrate that has been subjected to the third polishing is sequentially subjected to scrub cleaning with an alkaline detergent, ultrasonic cleaning in a state immersed in an alkaline detergent solution, and ultrasonic cleaning in a state immersed in pure water. dry.

In the primary polishing step, the secondary polishing step, and the tertiary polishing step, the polishing pad mounted on the upper surface plate and the lower surface plate of the double-side polishing apparatus has diamond abrasive grains on the surface before polishing the glass substrate. A dressing process is performed using a dressing jig to form a polished surface having a predetermined flatness.
[Inspection process of glass substrate for magnetic recording media]
The main surface of the glass substrate for a magnetic recording medium obtained by the above steps is measured using an optical surface inspection apparatus (OSA (Optical Surface Analyzer) 6300 manufactured by KLA-Tencor), and local roughness defects are measured. Check for the presence or absence of. The local roughness defect is measured in the recording / reproducing region of the main plane of the glass substrate for a magnetic recording medium using scattered light obtained by irradiating the main plane of the glass substrate with laser light having a wavelength of 405 nm. In this inspection process, the glass substrate W in which the traces N1 and N2 (local roughness defects) shown in FIGS. 6A and 6B are confirmed is determined to be unacceptable. Moreover, in the present Example, the test | inspection measurement of the presence or absence of a local roughness defect extracted and measured 30 glass substrates from the same lot.

  In the glass substrate of the lot to which the object to be polished suction jig 10 of the present invention was applied as the final finish polishing step (third polishing), local roughness defects were not observed, and all were acceptable products. On the other hand, traces N1 and N2 (local roughness defects) shown in FIGS. 6A and 6B were confirmed on the glass substrate of the lot manufactured without using the object to be polished suction jig 10 of the present invention. .

  Thus, the glass substrate for magnetic recording media without a local roughness defect can be obtained by the manufacturing method of the glass substrate for magnetic recording media using the to-be-polished object adsorption jig 10 of this invention.

  In the above embodiment, the double-side polishing apparatus for polishing a glass substrate for a magnetic recording medium has been described as an example. However, the present invention is not limited to this, and the present invention is also applied to polishing an object to be polished other than a glass substrate. Of course you can.

  Specific examples of glass substrates to which the present invention can be applied include glass substrates for magnetic recording media, photomasks, displays for liquid crystals and organic EL, optical components such as optical pickup elements, optical filters, and optical lenses. It is mentioned as a typical thing.

  Further, the number of glass substrates placed on the lower surface plate is not limited to a specific number, and any glass substrate can be used as long as it can simultaneously polish a plurality of glass substrates in one polishing process.

DESCRIPTION OF SYMBOLS 10 To-be-polished object adsorption | suction jig | tool 12, 13 Grasping part 14 Negative pressure introduction channel | path 20 Polishing apparatus 30 Upper surface plate 40 Lower surface plate 42 Polishing pad 50 Vacuum generator 52 Vacuum tube 60 Cylinder 62 Cylinder chamber 64 Negative pressure introduction hole 66 Air | atmosphere introduction Hole 68 Step part 70 Operation member 72 Central hole 74 First communication hole 76 Second communication hole 80 Spring member 78 Pressed operation part 90 Base 92 Central hole 94 Branch hole 96 Communication path 98, 99 Escape part 100 Adsorption pad 102 103 Escape portion 104 Suction hole 106 Suction layer 106a Suction surface 107 Support layer 108 Adhesive layer 120 Glass substrate storage container N1, N2 Trace

Claims (9)

In a workpiece suction jig having a suction pad that sucks the main plane of the workpiece,
An air suction hole communicating with the suction surface of the suction pad;
A cylinder communicated with the air suction hole;
An operating member inserted into the cylinder;
A spring member that returns the operating member to a negative pressure stop position before the operation,
When the operating member is pressed against the spring force of the spring member, negative pressure is generated on the suction surface of the suction pad, and when the pressing operation on the operating member is released, the spring member A polishing object suction jig characterized in that the operation member returns to a negative pressure stop position by a spring force to bring the suction surface of the suction pad to atmospheric pressure. The suction pad is
An adsorption layer having an adsorption surface in contact with the main plane of the object to be polished;
A support layer adhered to the back surface of the adsorption layer;
An adhesive layer that adheres the back surface of the support layer to a pedestal;
The to-be-polished object adsorption jig of Claim 1 which laminated | stacked.   The to-be-polished object adsorption jig according to claim 2 in which said support layer is formed with a nonwoven fabric.   4. The polished object adsorption jig according to claim 2, wherein contour shapes of the adsorption layer and the support layer are smaller than an outer periphery of the polished object and are non-circular.   The polishing object adsorption jig according to claim 1, wherein the object to be polished is a glass substrate for a magnetic recording medium. After polishing the main plane of the glass substrate, a method for producing a glass substrate, wherein the glass substrate is taken out using the polishing object adsorption jig according to any one of claims 1 to 4,
After the polishing of the main plane of the glass substrate is completed, the procedure 1 is to bring the suction surface of the suction pad of the workpiece suction jig into contact with the main plane of the glass substrate;
A procedure 2 for generating a negative pressure on the suction surface by pressing the operation member of the object to be polished;
Procedure 3 for taking out the glass substrate together with the object to be polished suction jig in a state where the suction surface of the object to be polished chucking is in close contact with the glass substrate;
With the outer periphery of the glass substrate inserted into each storage part of the polishing object storage container, the pressing operation of the operation member of the polishing object suction jig is released to stop the negative pressure generation of the suction pad. Procedure 4 for inserting the glass substrate into the storage portion of the glass substrate storage container;
The manufacturing method of the glass substrate which has this.   The method for producing a glass substrate according to claim 6, wherein the glass substrate is a glass substrate for a magnetic recording medium. A glass substrate for a magnetic recording medium, which is taken out from the polishing apparatus using the object to be polished adsorption jig according to any one of claims 1 to 4, after the main plane is polished by a polishing apparatus,
The glass substrate for a magnetic recording medium is a glass substrate for a magnetic recording medium having no local roughness defect measured using scattered light obtained by irradiating a laser beam having a wavelength of 405 nm in a recording / reproducing region on a main plane. A disk-shaped glass substrate for a magnetic recording medium having a circular hole in the center,
The magnetic recording medium glass substrate has no local roughness defect measured by using scattered light obtained by irradiating a laser beam having a wavelength of 405 nm in a recording / reproducing region of a main plane. Glass substrate for media.